Ecologist's Notebook

Mixed nuts Photo by S. Ross. Wikimedia Commons

(Click on the following link to listen to an audio version of this blog … Dietary nuts and seeds

Including nuts as a part of a healthy diet is an idea strongly supported by nutrition scientists.  In 2003 the “Food and Agricultural Organization” of the “World Health Organization” noted that there was a “probable association between unsalted nuts and a decreased risk of cardiovascular disease.” In 2012 the “Nordic Nutrition Recommendation” explicitly recommended the consumption of nuts and seeds as a nutritional safeguard for better health. For many years, seeds and nuts have been recognized as an excellent source of protein and unsaturated fatty acids, but more recent studies have stressed that their high levels of polyunsaturated fatty acids, vitamin E’s, minerals, dietary fiber, polyphenols, flavonoids and phytosterols may be possible counter-agents to the rampant cardiovascular diseases afflicting people in almost every society.

From these recommendations, the “Healthy Nordic Diet” and the “Dietary Approaches to Stop Hypertension” were developed. There have also been a large number of self-defined “Mediterranean Diets” and a wide range of “Plant-Based/Vegan” diet plans that have all included anywhere from three servings of nuts and seeds per week to two or three servings of nuts and seeds a day as a part of their dietary strategies. In general, most nutritionists agree that having at least 30 grams of unsalted nuts a day (20 almonds or 15 cashews) can have significant effects on a person’s health.

It is not surprising that with this increased dietary emphasis on eating seeds and nuts, the worldwide  production and consumption of these products has substantially increased. The  global production of nuts was 3 million metric tons in 2008/2009 but this value almost doubled (to 5.3 million metric tons) by 2022/2023! More and more nut farms are being established to satisfy the growing demand for dietary nuts. More and more land and other resources are being dedicated to the growing of these products.

Walnut with husk. Photo by B. Friedrich. Wikimedia Commons.

A ”nut,” by the way can be defined in two ways. Botanically, a nut is the fruit of a tree that has a hard, tough shell encasing and protecting the edible seed. By this definition, chestnuts, hazelnuts, pecans and walnuts are true nuts. There is also, though, a culinary or dietary definition of a nut that includes the botanical nuts and also the “nuts” that are actually seeds that develop inside of fleshy fruits that grow on trees. These additional dietary nuts include cashews, Brazil nuts, almonds, pistachios and macadamia nuts. To make the term “nut” even more confusing, peanuts, which really legumes whose shelled seeds develop underground, are also classified, dietarily, as nuts!

Cashew “apples.” Photo by A. Jacob. Wikimedia Commons.

Tree nuts (a general term for the true nuts and tree-grown dietary nuts) in order of the highest total annual production to the lowest are: almonds, walnuts, cashews, pistachios, hazelnuts, pecans, Macadamia nuts, pine nuts and Brazil nuts. Most almonds (80% of total world production (TWP)) are grown in the United States (primarily in California), most walnuts are grown in China (51% of TWP), most cashews are grown in the Ivory Coast and India (combined 43 % of TWP), the leading producer of pistachios is the United States (49 % of TWP), most Hazel nuts are grown in Turkey (70% of TWP), most pecans are grown in the United States (80 to 90% of TWP), the leading producers of macadamia nuts are South Africa (26% of TWP) and Australia (22% of TWP), the leading producers of pine nuts are China (53% of TWP) and Russia (19% TWP), and most Brazil nuts are grown relatively equally in Bolivia and Brazil (92% of TWP).

Peanuts. Photo by I. Leider. Wikimedia Commons

Peanuts are grown in China (37% of TWP) and India (13% of TWP) followed by Nigeria (6% of TWP) and the United States (5% of TWP). The state of Georgia is the center of peanut production in the United States a fact that was made quite famous by a Georgia peanut farmer who became president, Jimmy Carter.

Overall, China is the largest total producer of tree nuts and peanuts in the world. The amount of land dedicated to growing tree nuts, though, is a relatively small percentage of the 5 billion hectares (12.4 billion acres) of total arable land on Earth. It is estimated that only10% of Earth’s arable land is planted in permanent crops like fruit and nut trees, oil palm plantations, cocoa plantations and coffee plantations.

A recent report in the journal Food and Nutrition Research (February 14, 2023) discussed a meta-analysis of previously published studies exploring the impact of dietary nuts and seeds on human health. The authors of this paper screened 23,244 references and then selected a much more limited number for their detailed analysis. The meta-analysis was conducted on a group of “cohort studies” (42 papers comparing health variables in populations that either did or did not consume seeds and nuts (these 42 studies involved 1,890,573 participants)), and a group of “randomized control trials” (RCT’s) (18 papers in which experimental groups consumed a prescribed amount of nuts and seeds over a set time limit and health variables were then assessed (these RCT’s had a total of 2,266 participants).

The analysis indicated a probable relationship between the consumption of nuts and seeds and a decreased risk of cardiovascular disease (particularly coronary artery disease). This impact was thought to be caused by the effects of the nuts and seeds lowering (very slightly) the participants’ low density lipoprotein (“LDL”) levels. LDL is commonly referred to as the “bad cholesterol” and is statistically correlated to accelerated atherosclerosis and coronary heart disease. There were also some suggestions, but no conclusive evidence that the consumption of nuts and seeds reduce the chances of having a stroke. Consumption of nuts and seeds did not have any apparent impact on Type 2 diabetes or blood sugar, and the data concerning fasting blood sugar levels and A-1C levels were conflicting and not clear.

Mixednuts. Photo by Melchoir. Wikimedia Commons.

So, seeds and nuts seem to help control the “bad” cholesterol and reduce the impact of coronary arterial disease, but they are not universal panaceas for good health. Seeds and nuts are also, as pointed out by a number of nutritionists, very high in calories and should, then, be consumed in moderation or, at least, eaten in place of other foods rather than as a supplement to one’s regular diet.

Over the next two weeks, I will discuss the ecology of the production systems for these nuts. Next week I will describe how almonds, cashews, walnuts, pistachios and hazel nuts are grown and processed. The following week, I will discuss pecans, macadamia nuts, pine nuts, Brazil nuts and peanuts are grown and processed.

2017 Eclipse. Photo by NASA. Public Domain

(Click on the following link to listen to an audio version of this blog … Cicadas are coming

This has been a Spring of spectacular events. First we had a total solar eclipse (on April 8) that stretched from western Mexico all across the U.S. up into Newfoundland in the far northeast corner of Canada. Then, a month or so later, there is a unique emergence of periodical cicadas all across the Southeast and into the heartland of the Midwest.

This 2024 emergence is unique because it involves the simultaneous emergence of a 17 year locust brood (Brood XIII, the Northern Illinois Brood) with a 13 year locust brood (Brood XIX, the Great Southern Brood), and these two broods are adjacent to each other across a long line through central Illinois! It is the first time since 1803 (when Thomas Jefferson was president!) that an adjacent emergence of very different types of periodical cicadas has occurred!

There are seven species of periodical cicadas, and they are found exclusively in the eastern United States from the Great Lakes down to the Gulf of Mexico. The three species in the northern portion of this range tend to have seventeen year life cycles while the four species in the southern portion tend to have thirteen year cycles. There is considerable overlap in the ranges of these different types but little potential for interbreeding because of the asynchrony of the emergences of their adult forms.

Periodical cicada brood map. USDA. Public Domain

Both the northern and southern cicada species form communities that have synchronously timed adult emergences. These cicada communities are called “broods.” These Cicada Broods were first described in the Nineteenth Century, and although there is some controversy as to how many broods there actually are, most authorities agree that there at least twelve broods of seventeen year cicadas and thirteen broods of thirteen year cicadas. The broods are dynamic communities influenced by changes in climate and habitat. A number of broods have died out since their initial descriptions while others have come into relatively recent existence.

There are over 1500 described species of cicadas in the world, but only the seven found in the eastern U.S. are “periodical.” The life cycle of a normal, “annual” cicada (like our yearly “dog-day” cicadas, for example (see Signs of Fall 1, September 6, 2014)) can span several years and typically includes an extensive larval stage in which the cicada lives underground feeding on the fluids of tree and other plant roots. In periodical cicadas this underground portion of the life cycle is stretched out to intervals of thirteen or seventeen years! These adult “magical” cicadas (their genus name is Magicicada!) spend their month in the open air after more than a decade and a half of a dark, subterranean life!

It is thought that the elongated subterranean existence of these cicadas is an evolutionary mechanism designed to protect the species from excessive rates of predation. By emerging en masse and in very large numbers the cicada population far exceeds the ability of their numerous predators to consume them (“predator saturation”). Some individuals, then, always survive and reproduce.

Photo by Pmjacoby

In a typical periodical cicada life cycle, the female cicadas, at the peak of their emergence concentrate themselves in wooded areas within their emergence range. These woods are filled with the incessant, buzzing songs of the males. The loudest songs and the largest gatherings of singing males attract the greatest number of receptive females. After mating, the female cicadas use their saw-like, posterior, abdominal appendages (their “ovipositors”) to dig under the bark of limbs of oak or hickory or dogwood trees. Into each of these gashes they lay one or two dozen tiny eggs. Each female then moves on to another limb and then another and another until they each have deposited their six hundred eggs into roughly forty different sites.

Six weeks or so after their Spring mass emergence the adult cicadas all die. Later that summer, the cicada eggs that haven’t been eaten by birds or ants, or rotted away by fungi, or destroyed by the summer heat hatch into tiny, ant-sized larvae that fall, mostly un-noticed, to the ground. The larvae then burrow six to eighteen inches into the forest soil where, among the tree roots whose fluids and exudates will sustain them, they begin a slow, steady growth and metamorphosis that will last the next thirteen or seventeen years.

Cicada molting to adult. Photo by B Rabaglia. Forestry Images

Then, in the early Spring of their emergence year, the larvae, now nearly fully grown, begin to dig their way back out of the soil. They pause about eight inches below the soil surface, and wait for the just the right weather to stimulate their emergence out through their soil turrets and mounds. A warm rain is often the trigger that brings the soil temperatures to 64 degrees F and initiates the cicada’s final climb up into the open air. Once up on the soil surface, the cicadas undergo a four or five day metamorphosis into their short-lived, flying adult forms. These adults then seek each other out, and keep the cycle going!

Adult periodical cicadas have stout, black to brown bodies that are just over one inch long.  They have two pair of membranous wings that are tipped in orange. The front wings are twice as long as the hind wings and have an open span of about three inches. The head is dominated by a pair of large, bulging, red eyes. They are slow flyers and are easily taken by a wide range of predators. Adult males have relatively hollow bodies that are designed to be resonance chambers for their buzzing, mating calls. These calls are among the loudest noises that can be made by an insect (up to ninety decibels!). The females have much heavier, more meaty bodies that are loaded with fat and protein with which they will make their eggs. Predators are especially fond of female, periodical cicadas!

Photo by LL Hyche, Auburn Univeristy, Bugwood.org

The cicadas emerge in incredible numbers. It is estimated that more than a million cicadas can be found in a single acre of suitable habitat. The 2024 emergence is expected to involve more than a trillion adult cicadas!

The adult periodical cicadas feed only moderately on plant fluids and do very little damage to trees or other vegetation via their feeding. Limb scarring from egg laying and larvae emergence can open some trees up to infections, but that too is usually without very much serious damage except in very young trees or in delicate, ornamental tree species like dogwoods. Even the larvae feeding on fluids from the roots of their host trees do not seem to greatly affect the overall health or rates of growth of the trees.

The remarkable thing about the 2024 adjacent emergence is that two very different cicada species will potentially be in contact with each other during their mating periods. Usually, these periodical cicadas are separated from each other by significant time periods. Will these two species interbreed? If so, what will be the outcome of this hybridization? Sterile offspring or, maybe, a new species of periodical cicada?

Manatees at Blue Spring State Park. Photo by D. Sillman

(Click on the following link to listen to an audio version of this blog … Florida 5 Manatees

It’s hard to say why certain animals are compelling and  charismatic. Seeing a moose cutting across your hiking trail, seeing a cougar staring at you from a high rock overhead, catching a glimpse of a wolf silently slipping back into the shadows of a forest, seeing a giant manta ray breeching next to your small boat as you run from island to island in the Galapagos: these moments are full of wonder and excitement! But, some animals exude their charisma by just sitting there and doing nothing: an American alligator sleeping next to a bike path in the Everglades, an American bison bull eyes half-closed standing like a statue next to the road in Yellowstone, or a few dozen manatees quietly sleeping as still as shadows in a warm-water river in Florida.

You just can’t your eyes off of them!

Montel (a green sea turtle). Photo by The Turtle Hospital

When we went to the Florida Keys in December 2022, there were three animals that I wanted to see: a sea turtle (I hadn’t narrowed my choice down to a species, I just wanted to see a big turtle!), an American alligator, and a manatee. By going to the Turtle Hospital in Marathon, Florida (our beach condo was right next to it!) I got two hours of sea turtle experience (and even, as a Christmas present from my daughter and son-in-law, adopted Montel, a “permanent resident” green sea turtle at the hospital (her injuries that lead to her hospitalization were too servere to allow her release back into the wild)). When we drove up to the Everglades I got several up-close-and-personal contacts with substantial American alligators who were napping on the side of the trail where we were walking.

But, sadly, no manatees: not in the sea grass beds just offshore from our beach house, not even on our spectacular kayak tour through the mangrove swamps on the Gulf side of Marathon Key. Returning to Florida this winter, then, a manatee sighting was at the top of our bucket-list!

I mentioned this to my old Pennsylvania, biking and guitar-playing friend, Don, who spends the winter in Osteen, Florida near Sanford with his wife, Andrea. Don said, “we know where the manatee are! Just come on down!” So, Deborah and I rented a car and drove two hours south from Amelia Island into the increasingly warmer and increasingly more humid Florida.

Florida sandhiil cranes. Photo by D. Wicks

When we arrived at Don and Andrea’s we were greeted by their resident, non-migratory, sandhill cranes ( the Florida subspecies of the sandhill crane, Antigone canadensis pratensis). The greeting bird walked right up to us, gave us a good look-over and then slowly walked off in search of something more interesting. I have mentioned these Florida cranes before (see Signs of Winter 13, February 25, 2021). Our manatee viewing was set for the next morning, so, we drove over to New Smyrna Beach down on the coast, had a great lunch at a dockside restaurant and then drove just south to Cape Canaveral National Seashore to see the sea turtle nests.

Sea turtles really utilize the protected spaces of this seashore! In 2023 alone, just under 17,000 sea  turtle nests were established here. Over 11,000 of them were green turtle (Chelonia mydas) nests and almost 6,000 were loggerhead turtle (Caretta caretta) nests. There were also a couple of dozen leatherback turtle (Dermochelys coriacea)  nests and one Kemps Ridely turtle (Lepidochely kempii)  nest. On average a sea turtle’s nest contains 110 eggs, so these Cape Canaveral National Seashore nests probably represented over a million and a half potential sea turtles! Most of the eggs are laid in the late spring or early summer and hatch, in batches, after 60 days of incubation.

Unfortunately, we were not able to get into the turtle nesting area. Park rangers, clad in bullet-proof vests and carrying really scary-looking, automatic weapons, blocked off the entry road. They were not in a mood to talk or explain why  we weren’t allowed to go into the reserve. They simply said that the parking areas were all full, so no one could drive in.

Armadillo. Photo by Vlad Lazarenko. Wikimedia Commons

We went for a quick walk on the northern-most and still open beach of the reserve and when we came out, the roadblock and the armed guards had moved on out to just outside the entrance gate. So we turned into the reserve and drove down the main road. There were people parked along the various beaches (including the nude beach which was, yep, nude!). There was no sign of overcrowding or any other reason for the road closure. No big drug busts, criminal apprehensions , no political visitors that needed to be protected, no secret rocket launches or maneuvers down on the Space Center to the south. It made no sense. The information kiosks and tourist centers were all closed up, and there was nothing to see but some armadillos (Dasypus novemcinctus)  running down along the roadside or laying mushed on the concrete. We drove out and waved at the guards. Strange afternoon!

The next morning we were up early to make the drive over to Blue Spring State Park. For most of the year, manatees are very solitary animals, but in the winter they need to seek out warm water (like warm springs feeding coastal rivers or power plant outflows). They then gather in large numbers at suitable sites. Blue Spring is a natural, warm water spring  (average temperature is 73 degrees F) that flows into the St. John’s River. The warmed section of the river is a much-used refuge for manatees especially on cool winter nights and early mornings.

Manatees. Phot by D. Sillman

We walked from the parking area down to the paved riverbank, and looked for manatees. There were supposed to be 60 manatees gathered in the river this morning. At first I didn’t see anything in the water, but, then, as my eyes got used to the sun-glare off the water’s surface and the rippling patterns of the intensely clear river water, I saw them! Silent, gray-brown shapes floating just above the river bottom. They were basking in the warm water and barely moving. They were awesome!

Manatees are huge aquatic mammals! They can be over 13 feet long and weigh up to 3500 pounds (although 1300 pounds is a reasonable average). They are herbivores that eat over 60 types of plants. They regularly spend 7 or 8 hours a day grazing and eat 10 to 15% of their body weight each day. They have prehensile lips and dexterous forelimb flippers that they can use to gather and manipulate vegetation. Their molars (their only type of teeth) grind up the vegetative materials and pass them along into their relative simple, but very elongated digestive system (they have 45 m of intestines!). They have six molars on each jaw and regularly grind down and lose their front teeth, replacing them with new ones in the back.  Unlike cows, they don’t have a partitioned stomach to facilitate the breakdown of all of the cellulose they ingest, but they do have, like a horse, a large cecum which acts as a digestion chamber.

Manatees. Photo by D. Sillman

Manatees ( this Florida species is Trichechus manatus, the “West Indian manatee”) live in the shallow, marshy coastal waters and rivers all through the Caribbean and the Gulf of Mexico. Other species of manatee are found in the Amazon and South America and also in West Africa. The Florida manatee occasionally travels up to surprisingly northern sites on the Atlantic Coast (they have been seen off New York City, Rhode Island and even Cape Cod!), but most typically they seldom stray much further north than Georgia. Manatees have surprisingly little subcutaneous fat and must stay in warm water to maintain their thermal equilibria.

According to the U.S. Fish and Wildlife Service, there are 6,300 manatees in Florida. Manatees have recently been removed from the Endangered Species List even though their mortality rates have been skyrocketing! In 2021 , 1100 Florida manatees died! In 2022, 800 Florida manatees died, and in 2023, 556 manatees died. Hurricanes, red tides, pollution, cold stress and starvation are typical causes of manatee deaths. Collisions with boats are often presented as a major cause of mortality, but typically there are “only” 100 manatee deaths a year due to strikes by boats. Most experts agree that starvation and a syndrome called “acute lethal gut shock” (caused by manatees eating less nutritious macro-algae rather than sea grass and other true plants) are the main causes of the exponential rise in manatee mortality.

Sea grass beds and other natural, coastal vegetation are being decimated primarily by human-generated pollution (including sewage and septic system drainage and agricultural field run off). Glyphosate herbicide residues (which are found at very high levels in almost all of Florida’s surface water) are especially toxic to sea grasses and other natural, coastal vegetation.

Manatee rescue. Photo by USFWS, Public Domain

We watched the manatees float in their groups of 10 or 12 for over an hour. Blue Springs is both a refuge for manatees and also a rehabilitation location. Just the week before, several manatees were brought to Blue Spring from a hospital facility and carefully released into the warm water. The rehabilitating manatees are clearly marked, and as they continue to heal they will be able to freely swim out into the coastal waters.

Great thanks to Don and Andrea for a wonderful manatee experience!

Red maples in flower. Photo by W. Hamilton

(Click on the following link to listen to an audio version of this blog … Florida 4 woods and swamps 2

(More on our hikes on the Ron Sapp Egans Creek Greenway Trail on Amelia Island.)

Red maples (Acer rubrum) were very abundant along the Greenway trails. They grew in wet lowlands and also up on the drier hillsides. They hadn’t made any leaves yet, but, like the red maples up in Pennsylvania they had flowered well before setting leaves and had made large numbers of bright red seed samaras. The samaras were larger (about twice as long!) than the samaras I remember from my red maples back in Pennsylvania. This intense red color stood out against the drab grays and browns of the “stick” forest. As I have previously said with regard to Pennsylvania forests (see Signs of Spring 8, April 14, 2016), late winter or early spring is the time to do a census of just how many red maples are in these forested ecosystems! It is quite obviously the most numerous tree species in the northern and also the southern Eastern forest!

Woods along the trail. Photo by W. Hamilton

Along with the reds from red maples, there were also splashes of green in the woods. These grrens were from scattered sweet bay magnolia (Magnolia virginiana), dwarf palmetto (Sabel minor) and slash pines (Pinus elliottii). There were also several, medium-tall, leafless trees that had a very characteristic branching pattern. The main branches of the tree out to all of its terminal twigs arose directly opposite each other, there was no staggered or alternate branching at all. These had to be ash trees, and looking up the types of ashes expected in these wet swamps, I assume that they were pop ashes (Fraxinus caroliniana).

Photo by D. Sillman

Another source of green colors along the hiking trail were the small, floating, water plants that covered almost all of the surface water of the swamp pools. This is a familiar plant species that invasively plagues many freshwater ecosystems back in Pennsylvania: duckweed (a variety of species in the sub-family Lemnoideae). Under normal conditions, duckweed’s rapid growth is balanced by a rapid dispersal rate. Also, the rate of its consumption (it is a high protein food eaten by many birds (waterfowl), fish and amphibians) balances its rapid rate of reproduction. When duckweed grows in water that is enriched in nutrients (like fertilizer runoff for example or phosphate pollution from household detergents), though, it can reproduce so rapidly that it overwhelms its aquatic ecosystem.

Great blue heron. Photo by D. Sillman

Wood stork. Photo by D. Sillman

There were many birds both in the swamp and out in the salt marsh beyond. A flock of broad winged hawks ( Buteo platypterus) kettled past overhead in great swirling arcs. A number of  black vultures ( Coragyps atratus), mostly flying alone or in pairs wobbled by in very straight-line flight paths. And, perched on the partially  submerged logs of the swamp pools and slogging through the muddy waters were anhingas (Anhinga anhinga), white ibises (Eudocimus albus), great egrets (Ardea alba), great blue herons (Ardea herodias) and a tall, powerfully beaked wood stork (Mycteria americans).

We saw several American alligators in the ponds and pools along the trail. Most of them were quiet and seemed quite sluggish in the cool mornings almost to the point of profound immobility, but alligators can get very busy very quickly and move surprisingly rapidly when the need arises!

As I wrote in a blog back in 2019 (Signs of Fall 3, October 3, 2019), the American alligator was brought back from the edge of extinction by the protections of the Endangered Species Act of 1973.  It now can be found in both freshwater and brackish habitats from the wetlands and lakes of Texas, all across the states bordering the Gulf of Mexico, and up the U.S. Atlantic coast as far north as North Carolina.

Why was it important to re-establish this formidable reptile in its former ecosystems, and why is it important to maintain them there? The answer revolves around the keystone nature of this species.

American aligator. Photo by D. Sillman

First and foremost, the American alligator is a predator. It opportunistically takes almost any prey species that comes into its strike zone. It especially eats large prey species that live in their aquatic habitats (especially large fish), and they also eat a wide range of terrestrial species that wade or swim across their aquatic habitats or come to the edge of their pools, ponds or streams to drink). American alligators have been known to take black bears, panthers, deer and wild boar but more commonly capture and eat smaller terrestrial prey like raccoons and muskrats. Control of these prey species is a very important ecological role of this species.

A very interesting “unintended consequence” of the extirpation of the American alligator from wetlands in Florida (which was motivated in part at least to stop the alligator’s consumption of game fish) was the precipitous drop in game fish populations after the alligators were gone. Researchers determined that the alligators preferentially consumed large fish (like gars) and that these large gars preferentially ate the game fish. Without the alligator-mediated control of the gar population, game fish numbers drastically declined.

American alligators also construct “gator holes” or “gator ponds” in their wetlands. The alligator uses its snout and tail to dig down through the accumulated muck and vegetation to create a relatively deep water pool in which it can hide and hunt. These pools fill up with freshwater and are often the only water sources that persist during times of drought. Many animals rely on these gator holes for drinking water during times of low rainfall (although they have to keep an eye out for the lurking, hunting alligator!).

Female American alligators also modify their wetland habitats via the construction of nesting mounds. These mounds can be as much as 3.5 feet high and up to 7 feet wide. These mounds serve not only as incubation sites for the alligator eggs but can also can significantly add to the topographic complexity of the wetland habitat. A variety of plant species that require slightly drier soils can grow on these mounds thus increasing the vegetative diversity of the wetland. Also, a significant number of bird and mammal species can use these mounds for their own nests and dens.

Chicken turtles on a log. Photo by D. Sillman

We saw quite a few turtles in the pools and ponds along the trail. There may have been more than one species, but this photograph enabled me to identify this “turtle train” as a set of chicken turtles (Deirichelys reticularis). Most of the turtles we saw in the still waters of the swamp forest were probably chicken turtles.

Chicken turtles are almost exclusively carnivores. The larger female chicken turtles especially eat larger prey like crayfish. The smaller chicken turtles (the males and the immatures) typically eat smaller prey like dragonflies, spiders and tadpoles. Chicken turtles are also know to eat carrion and, rarely, vegetation.

Chicken turtles are aquatic, but they regularly spend many months of the year on dry land (typically in forested habitats). The transient nature of many of their marshy pools and the high probability of their muddy ponds seasonally drying up is a logical ecological and evolutionary motivation for their adapting to occasional life in dry habitats.

(Next week: Manatees!)

Great egret, anhinga and chicken turtle in pool along Red Trail. Photo by D. Sillman

(Click on the following link to listen to an audio version of this blog … Florida 3 Woods and swamps Part 1

The Ron Sapp Egans Creek Greenway is a 300 acre park that stretches out along Egans Creek on the northeast side of Amelia Island, Florida. The park opened in 2000 and is named after Ron Sapp who as city commissioner was instrumental in securing funding and generating public support for the Greenway project. The park is maintained in as natural a state as possible and has over four miles of graveled, packed dirt, and grass-covered walking and biking trails that wind through freshwater swamp forests in its southern and central sections and saltmarsh and maritime forest in its northern sections.

We parked at the southern tip of the Greenway and walked off past a broad pond and then over a pedestrian bridge to begin our hike on the Red Trail of the Greenway. Basking on the shore of the pond were numerous turtles, two American alligators and a resting flock of brown pelicans.

Winer woods along Red Trail. Photo by W. Hamilton

Since it was mid-February, very few of the deciduous trees along the trail had any leaves. This made them very difficult to identify! The swamp forest that surrounded the hiking trail was a dense, tangled mass of layered vegetation (there was a heavy ground cover, a thick shrub layer and an emergent tree canopy layer). These vegetative layers were filled with mostly bare trunks and branches and browned hints of past vegetation. All of this woody material was tightly interwoven around the edges of the stagnant water pools.

Male anhinga next to pond. Photo by D. Sillman

I remember being told by my forestry professor when I took dendrology at Ohio State that taking a similar course in the south was considerably more work! The diversity and species richness of the warm, wet, southern forests are staggering! For example, Florida forests have 262 native species of trees while Ohio forests only have 99! Looking into these mostly leafless thickets bordering the trai, all I could imagine were all of the tree species I had never seen before, and that most of them didn’t have any leaves! Help!

Some of these “ standing sticks” were definitely cypress trees. These were very recognizable in spite of their lack of defining needles (cypress is a deciduous conifer) because of their distinctive “knees” that poked up through the surface of the dark water of the pools. These knees enable the underwater roots of the cypress trees to get oxygen even as they grow through the very anerobic muds of swampy pools.  These knees are a vital adaptation that enable cypresses to live in their water-dominate swamp habitats.  Bald cypress (Taxodium distichum) and its very similar (but slightly smaller) con-generic, pond cypress (T. ascendens) were probably both well represented along the edges of the swampy pools.

Photo by W. Hamilton

Another feature of cypresses which helps in their identification even in these leafless, winter months is the presence of the epiphyte called Spanish moss (Tillandsia usneoides). Long streamers of Spanish moss drape over the branches of cypress trees. Spanish moss is a non-parasitic plant (it does not harm the tree on which it is growing) and tends to be primarily and possibly exclusively found on cypress trees (especially bald cypress) and also on live oaks (Quercus virginiana)). There were no live oaks in these very wet, swampy woods (live oaks prefer slightly drier soils). Also, live oaks retain their leaves in the winter (hence their descriptive name “live!”) and would have stood out very clearly against the gray-brown dominance of the leafless swamp woods.

The dense patches of Spanish moss scattered along the barely flowing swamp-river, to me, indicated localized abundances of cypress trees!

Spanish moss. Photo by PxFuel

Spanish moss is a very interesting plant although it is very oddly named. It is not from Spain (early Spanish explorers in the American Tropics, apparently had some colorful encounters with the plant and, so, their country’s name was appended to it!), and it is not a moss! It is rootless vascular plant that is in the same plant family (Bromeliaceae) as the pineapple! It has a high degree of specificity upon which trees it grows. As I mentioned above, cypress trees (especially bald cypress) and live oaks are by far the most common “host trees” for this epiphyte (although, the black tupelo (also called the “black gum”)(Nyssa sylvatica) is sometimes listed as possible Spanish moss host)! Two possible reasons for this tree preference of Spanish moss have been offered: 1. The barks of both the bald cypress and the live oak are heavily fissured and, thus, give the Spanish moss strands something realtively solid to hang onto, and 2. The leaves of the bald cypress and the live oak leach high quantities of inorganic nutrients (like calcium, magnesium, potassium and phosphate) and these nutrients are needed for the growth of the moss epiphyte!

Great blue heron and his turtle army! Photo by D. Sillman

It is very amazing to me that the expert consensus of the impact of dense coverings of Spanish moss  on the branches of the “host” trees have no negative impacts on the growth or survivability of the tree! In fact, these moss masses hold so much water (a clump of Spanish moss can retain up to 10x it weight in water) that they may act to cool the tree during very hot, summer days. The Spanish moss, then may actually be a mutualistic symbiont for these southern trees!

The Spanish moss masses are well used by animals. Birds make nests out it, numerous insects, spiders, bats and snakes live in the clumps or, at least, find refuge there. If you ever happen to tug on a bunch of Spanish moss (it is relatively lightly attached to the tree, so the clumps pull free fairly easily) be careful because often the clumps have snakes in them. There is even a species of jumping spider (Pelegrina trillandstae) that is ONLY found in Spanish moss!

Spanish moss is very sensitive to air pollution. It is declining considerably in forests near urban or industrial areas.

Beard lichen. Photo by Geograph

There is a group of lichens that very closely resemble Spanish moss. These lichens (and remember lichens are composite organisms of algae and fungi) are called “beard mosses” or “beard lichens.” These lichens may also be called “old man’s beard,” although that name can confuse these lichens with a vascular plant (a clematis) of the same name.  These Spanish moss-like lichens are species in the genus Usnea, and, emphasizing the similarity of the appearance of these lichens to Spanish moss,  Usnea is the root of the scientific species name of Spanish moss (“usenoides”).

The Usnea lichens are, like most lichens, quite rich in chemicals. Some of the Usnea chemicals have been used in traditional medicine to treat bacterial infections, sore throats and even lung infections. One of the more abundant chemicals in these Usnea lichens is usnic acid. Usnic acid can have negative effects on other plants and also upon animals that eat the lichens.

We took a day during our Amelia Island visit to drive down to Osteen, Florida where we visited some old friends (Don and Andrea) from Pennsylvania. While we were there Andrea mentioned that she had been using Spanish moss as a mulch on her outdoor, potted plants, but that someone had pointed out to her that she was, in fact, using something that resembled Spanish moss, and it was very likely to kill her plants! She had put strands of beard lichens around her plants, and the usnic acid was making the soil in the pots intolerably acidic.

(Next week: more on the woods and swamps of Amerlia Island!)

Dune with beach grass. Photo by Ellyway. Wikimedia Commons

(Click on the following link to listen to an audio version of this blog …. Florida 2 beaches and dunes part2

(Continuing the discussion of the beaches and dunes of Amelia Island, Florida)

The seaward face of the first dune (the “primary dune”) rises steeply from the gentle upward slope of the dry, upper beach. The exposed face of this primary dune is, on average here in Amelia Island, four or five feet tall and is made up of loose sand that is dominated by relatively coarse sand grains. The upper beach and the primary dune face are heavily used by people visiting the beach. They are well covered with foot prints and indentations where coolers, bags, folding chairs and beach gear have been stashed. In some places the front of the dune have been worn down by the passage of the feet of many visitors.

Near the top of sea-facing dune the beach grasses begin. These plants have fantastically deep roots and are also able to tolerate the salt spray that blows in from the waves crashing down on the intertidal beach. These beach grasses continue down the gentle slope of the landward side of the primary dune and continue in clumping distributions back through the undulations of the subsequent dunes and their interdunal recesses.

The sand grains on this leeward dune face are smaller and, therefore, lighter in weight than the sand particles in the seaward facing part of the dune. The onshore winds have pushed the heavy sand particles to the front face of the dune and blown fine clouds of smaller sand particles up over the peak of the dune where they have scattered and slowly settled out on the leeward slope.

Back dunes. Photo by D. Sillman

The beach grasses generate favorable microhabitats for the growth of other plants. These other plants cluster around the beach grass clumps and then begin to fill in the open spaces around the clumps. Palmettos (scrub palmetto?), bay laurel, thistle and opuntia cactuses (“prickly pears”) along with an array of low growing flowering plants make the interdunal areas and, eventually, the dunes themselves increasingly dense, shrubby vegetative habitats.

Shrubby back dune. Photo by D. Sillman

In a natural system, these shrubby communities would further develop into pine dominated maritime forests, but here on the Amelia Island coast, a bordering line of condos, beach houses and roads has been built on the site of the old maritime forest. There are, though, patches of maritime forest at the northern end of Ron Sapp Egans Creek Greenway trail (and I will describe this trail in a future blog). In these truncated sand dune systems, the primary dune is the tallest and most substantial dune. Behind it, to landward, are typically a set of 3 to 4 small dunes that stretch back the 30 or 40 yards to the front edges of the buildings built along the dune-front road.

These secondary dunes are poorly structured and don’t seem to be a very substantial protective barrier for the land. A very nice feature of these “back dunes,” though, are the elevated walkovers that keep beach-goers from trampling on the delicate dune surfaces. These wooden walkways connect the streetside parking lots with gaps in the primary dunes and allow foot traffic back and forth over the secondary dune systems.

Gopher tortoise in back dunes. Photo by D. Sillman

These walkovers also provide a good perch to observe some of the animals that live in the interdunal habitat. I saw several gopher tortoises (Gopherus polyphemus) lounging in the openings of their burrows. Gopher tortoises are an endangered species whose population numbers have been decimated by habitat degradation and loss. These tortoises are also keystone species in their dune ecosystems. Their burrows are, according the Florida Fish and Wildlife Commission, important refuges for over 350 native animal species including the threatened Eastern indigo snake, the burrowing owl and the gopher frog. This tortoise is protected by both Federal and Florida law.

Pausing on a walkover to watch a tortoise slowly tear apart a pumpkin that someone had dropped for him, I spoke with a gentleman who owned the beach house that edged that stretch of dune. He called the dune system his “front yard” and was very attentive to the gopher tortoises living there. He said that he didn’t know who had given the tortoise the pumpkin but said that he often put out lettuce and apples for “his” tortoises.

Marsh rabbit. Photo by W. Hamilton

Also living in the secondary dunes and visible from the walkover are marsh rabbits (Sylvilagus palustris) (also called “marsh hares”). Marsh rabbits are small, brown cottontail-like rabbits with comparatively short ears and legs and small tails. They are known to be extremely strong swimmers and are quite abundant in the marshy areas of the coastal islands. I had the pleasure of seeing one of these rabbits darting about while I was watching a tortoise slowly doing nothing at all!

I had expected to see quite a few birds down on the beach, but the numbers were disappointing. My guess is that overwintering birds would probably be located further south in the warmer sections of southern Florida. I did see a few least sandpipers (Calidris minutilia) and some spotted sandpipers (Aactitis mcularius) in their unspotted, winter plumage probing the sands just at the tideline and moving steadily southward down the beach.

Herring gulls (Larus argentatus) were very precisely scattered across the intertidal and upper beaches. The individual birds were almost always solitary and maintained a distance of 20 or 30 yards from their nearest neighbor even as they moved up and down the beach. The much smaller laughing gull (Leucophaeus atricilla) mixed in and around the herring gulls and were much more randomly spaced on the beach. The laughing gulls often bunched together and then quickly dispersed only to form new groupings several feet way.

I also saw one immature bald eagle (Haliaeetus leucocephalus) flying overhead one afternoon. He flew out just over the ocean waters and raced south at a very impressive speed. He was out of sight, in fact, in what seemed like just a few seconds!

I did see quite a few birds on my walk through a wetland forest. I will talk about those in another blog.

Two color forms of A. carolinensis. Female has light back stripe. Photo by R. Michniewicz. Wikimedia Commons

At Randy and Charlene’s rental house I also saw a number of reptiles and birds. The side of the house and the surrounding philodendron bushes and palmettos were alive with small, green anole lizards (Anolis carolinensis). The green anole is native to the American Southeast and has a range that extends all the way over to the Texas Gulf Coast. We had these “chameleons” (a very common name even though they are not really chameleons at all) all over our house in Houston. Even though they are not true chameleons, they do have the ability to change their body color. They can change from green to brown depending on their need for specific camouflage. These lizards eat all sorts of insects and spiders and are, in turn, eaten by many birds, larger lizards, snakes and dogs and cats. Many years ago, I made an 8 mm movie of my cat, Sam, hunting and eating anole lizards back in Houston. Unfortunately, that movie has been lost in the clutter of time!

Eastern black racer (coiled next to wall). Photo by W. Hamilton

We also had a daily visitor at the rental house who curled up next to the side of house under the cover of the palmettos. Depending upon the morning temperatures, he would show up in the early morning or, sometimes, later in the day. Deborah and I had a ritual with our first cup of morning coffee to go over to the corner window of the sunroom and say “good morning” to “our” snake!

He was an Eastern racer (Coluber constrictor). I estimate that he was 2 to 2 ½ feet long, but he was so tightly coiled up on the dry leaves and sticks under the bushes that it was hard to precisely tell. He was relatively thin, solid black on his back and sides (I couldn’t see his belly). This uniform dark coloration indicated that he was an adult.  I assume that he was primarily living on the green anole lizards who were darting around on the branches above him, or maybe on the little rodents scuttling around in the vegetative debris of the shrub beds. Racers are the most common snake found in Florida neighborhoods. They eat small rodents, lizards, frogs, toads, and insects. They can also climb into birds’ nests and eat eggs and nestlings.

Also at the rental house I saw a bird that I have missed very much since we moved to Colorado: the northern cardinal (Cardinalis cardinalis). Cardinals were one of our most abundant birds around our old home back in Pennsylvania, but they aren’t found as far west as Colorado. It was wonderful watching them fly about in their mixed flocks with titmice, chickadees and Carolina wrens around the dense array of tree limbs that bordered the rental house’s back yard!

(Next week: hiking on the Greenway Trail!)

Amelia Island at sunset. Photo by J. Kennaw. Flickr

(Click on the following link to listen to an audio version of this blog … Florida 1 beaches and dunes

(I want to thank Randy and Charlene Rezabek for inviting Deborah and I to visit their rental house on Amelia Island in February! They showed us such a wonderful time! I hope that we get to do more ocean adventures together!)

Back in mid-February, I was standing at low tide on the wide beach of Amelia Island and thinking about all of the other beaches I have had the pleasure to visit over the decades of my life. My first surf dunking was in 1959 at Virginia Beach (I was seven years old and the waves looked huge!). After we moved to Houston in 1966, I had ten years of almost constant residence on the beaches up and down the Texas coast. During my 34 years at Penn State, we took frequent family vacations to the shore, and I also taught a yearly field biology course on Chincoteague and Assateague Islands in Virginia. More recently, we visited the Florida Keys in December, 2022, and, this winter, came back once again to Florida.

Amelia Island beach. Photo by D. Sillman

Standing on these beaches and coastlines, tossed and blown by the wind, listening to the sea gulls screaming and the waves crashing, smelling the salt air and the rich, fish-scent of the ocean, the overriding sensation that puts everything else in context is the sight, the feel and even the taste of sand!

Sand is a system of particles primarily made up of quartz (silica dioxide). Sands are classified by their particular size range (0.074 to 4.75 mm in diameter). A sand particle is smaller than a piece of gravel but larger than a silt particle. Most of these pieces of sand-quartz come from the weathering and erosion of the massive rocks that once made up the surfaces and cores of faraway mountains.

Sand particles are so irregularly shaped that when they are piled together the spaces in between them are relatively large. In fact, these spaces are large enough to allow water to flow through them under the pull of gravity. When a system of sand is saturated with water these channels fill up and the cohesiveness of the water molecules weakly holds the sand particles together. This is why you can use wet sand to build sand castles on the beach! The wet sand, though, quickly loses its water (via gravitational drainage and also evaporation) and then the sand castle crumbles apart.

If a sand system has a water-impermeable layer beneath it, it can hold water for a long period of time. This sand, when saturated with water, will behave like a thick liquid and compress and flow like any fluid system. Offshore sand is saturated with water and flows in a very fluid manner. So, sand can blow about when it is dry, and ooze and flow when it is wet. Sand is capable of many types of movements!

Beach sand dune. USFWS. Public Domain

Beaches are strips of sand (or sometimes strips of gravel, shells or pebbles) located between oceans or lakes and the land that abuts them. Dunes are structures on the landward side of a beach. Dunes form from beach sands that are pushed away from the ocean or lake by on-shore winds. Dunes also typically require plants or some other vertical impediments to slow down the passing air-borne sand so that it will accumulate in a slowly building mound. Plant roots also help to hold the very shiftable, dry sand together!

Beaches and dunes are dynamic, constantly changing systems. They are shaped by the daily actions of winds, waves and tides and also by the very occasional but extremely spectacular events of high energy, catastrophic storms.

Beaches act as energy buffers against the destructive action of coastal storms. In general, the wider the beach the greater the potential degree of protection. Dunes also protect the land from storms especially with regard to storm surge. Again, the wider, and taller, the dune system is, the greater the degree of storm surge protection.

The exchange of sand from beach to dune slowly builds the dune. Dunes may also, under certain circumstances, “give back” sand to the beaches especially after a particularly severe storm-induced beach erosion event.

South tip of Amelia Island. State of Florida. PUblic Domain

There is, though, a third reservoir of sand connected to the beach/dune system. This third, sand reservoir is actually much larger than the beach and dune reservoirs combined. This third sand reservoir, though, is usually hidden from view just off-shore from the beach! This is, of course, the immense sand reservoir of the ocean floor and its often barely submerged accumulation of sand in off-shore sand bars. This off-shore sand can move up and down a beach building zone. It is the ultimate, natural source of the sand for all of our coastal beaches and dunes.

Storms may return the beach and dune sands to these off-shore sand reserves and, thus, re-start the whole process of beach and dune building. The steady pulse of waves and tides with their relatively rapid landward flowing velocities and slower seaward flowing velocities inevitably push and carry the off-shore sand to the beach. As long as there are no hard barriers in the way (like sea walls, jetties and groins) the sand will return and the beaches and dunes will re-form even after cataclysmic destruction.

The forces acting on the sand generates a distinctive, “rolling” profile to the sand bar/beach/dune system. This undulating landscape stretches from the submerged, off-shore sand bars all the way inland as far as the dunes are allowed grow.

Here on Amelia Island, the off-shore sand bar is not visible even at low tide. It is possible that dredging has reduce its volume so much that there is not a hint of its presence under the rolling surf. Up at Assateague Island in Virginia and at Surfside Beach in Texas I remember seeing a distinct “browning” of the ocean water over the off-shore bars. In Texas, at low tides, the off-shore sandbar actually emerged from under the water and served as a resting place for sea gulls and pelicans.

National Park Service. Public Domain

In between the sandbar and the emergent (“intertidal” or “face”) beach is a deep “trough” and then a long, submerged, concave dish of sand called, very logically, the “submerged beach” or “terrace”). When this submerged beach reaches up sufficiently high to be exposed at low tides, it then forms start of the “intertidal beach” which extends all the way up to the maximum high tide line. This intertidal beach maintains the distinctive undulating topography with rolling crests and depressions that run all the way up to the dry line of the “upper beach” (or”berm”). The upper beach, then, makes contact with the start of sand dune system.

We often went down to beaches here on Amelia Island at low tide. That gave us more beach to explore and also a greater opportunity to find interesting shells and sharks’ teeth! Even at extreme low tide, though, there was a substantial water flow from the upper part of the intertidal beach back to the ocean water line. In places this water flow had dug gullies in the intertidal sand that were a foot or two deep. These gullies carried a significant water volume down the beach profile and made walking along the beach difficult.

Where did this water come from? Exploring the upper edges of the intertidal beach I noticed a long, broad concavity that very likely filled with sea water at high tide. The sand of this concavity was fluid underfoot and was obviously saturated with water. There must have been a rock pan under this area of the beach that kept the water in the spaces of the sand system from draining downward via a gravitational pull. This water, though, did flow out laterally toward the low tide line. Small seeps and trickles from the sand gathered together into an Artesian spring-like flow that then cut through low spots in the beach and dug the water-filled gullies down to the ocean.

At high tide, the water flow in these gullies would reverse sending the incoming tidal water up into the upper tidal beach concavity. As long as the gullies maintained their structural integrity, this in and out flow of water would continue!

(Next week: Dunes!)

Gray_wolf_(female). Photo by D. AVery, Wikimedia Commons

(Click on the following link to listen to an audio version of this blog … Colorado Wolves

Back in November, 2020 I voted for the first time as a new citizen of the state of Colorado. One of the items on the ballot was an initiative entitled “Proposition 114.” Proposition 114 basically asked the question, “should gray wolves be re-introduced to mountains of Colorado?”

Taking a question like this to voters was an idea that had never been tried before. Some opponents of this proposition disparagingly referred to it as “ballot biology,” but the science behind the re-introduction was solidly built into the proposition. The intent of this vote was to assess the willingness of the people of Colorado to once again have gray wolves roaming around on the western slopes of the Colorado Rockies. Before the vote, public opinion surveys indicated an 80% approval rating for wolf re-introduction. The actual vote, however, was much closer. The proposition passed but only by a razor thin margin of less than 1%!

Proposition 114 required that the Colorado gray wolf re-introduction begin before the end of 2023. Wildlife biologists worked hard to develop a plan and a set of locations for the wolf re-introduction and line up approval from the U.S. Fish and Wildlife Service. Ranchers and a number of other interest groups worked equally hard to cancel or delay the re-introduction. Ignoring the science behind the proposition, the program was politized into a Left vs. Right, Liberal vs. Conservative, Democrat vs. Republican dispute.

A number of Republican-controlled states (Montana, Wyoming and Utah) refused Colorado’s request for wolves. Finally, Oregon agreed to trap and transport wolves for the Colorado program.  Legal disputes and court battles went on until mid-December 2023!

Gray Wolf. Photo by USFWS. Public Domain

The final court decision came down in favor of the wolf release, and on December 18, 2023, with 45 people on hand to watch (including Jared Polis, the governor of Colorado) five wolves captured just the day before in Oregon, were released in the mountains of Grand County, Colorado.

The five released wolves included two, one-year old sibling pairs (male and female siblings) and a two-year-old male. The wolves left their cages in very different manners: a few bolted out of the cages and ran straight for cover of a nearby forest, a few lingered in their cages and seemed to finally come out with great reluctance. One of the females stayed in her opened cage for so long that several people (including Gov. Pollis) went over and looked into the open cage door. Eventually, though, all of the wolves left their cages and ran out into surrounding forest.

However, as John Ewen, a conservation biologist with the Zoological Society of London, put it in an interview with The Scientist: “The opening of the cage door is just the beginning of a very long journey to recovery.” Over the next five years between thirty and fifty wolves will be released in the Colorado mountains. Their locations, pack sizes and activities will be monitored closely by the state’s wildlife biologists. These new “Colorado wolves” will fill-in the “wolf-less” open space in the north-south mountainous stretch between Mexico and Canada. Wolves now live all across the backbone of America!

Inevitably, the wolves will kill livestock. There is a generous compensation plan to try to help reduce the economic impacts of wolf-kills on Colorado ranchers. Payments up to $15,000 per animal will be made in the case of livestock deaths.

Gray wolf. Photo by HFSchwartz, Forestry Images

The whole idea of putting species back into the ecosystems where they once were integral components is relatively new. In particular, the re-introduction of large predators, animals that were routinely and enthusiastically annihilated with guns, traps and poisons, is extremely controversial. The science that enumerates the benefits of adding predators to a biotic community has been developing and growing over the past 60 years, but the deeply felt emotional reaction against large, predaceous animals is something that is difficult to overcome by logic alone.

Prior to the late 1950’s is was accepted in conservation biology that large predators were for the most part undesirable components of ecosystems. Not only did they threaten both human lives and livestock, but they also harmed wild, grazing animals and added little to the overall sustainability or vigor of a biotic community. Herbivore populations and plant populations were obviously and intricately interconnected and highly controlled, but predators had only negative impacts on their ecosystems. There would be more deer for deer hunters, the logic went, if there were no cougars or wolves. The ecosystems would be more productive and more robust if the “killers” were only removed.

Gray_Wolf. Photo from httpknowledgebase.lookseek.comGray-Wolf-Canis-lupus.html, Wikimedia Commons

And removed they were! Funded by bounties on large predators like wolves and cougars (and also smaller predators like coyotes (see Signs of Spring 3, March 19, 2020)) federal and state programs drove these predators out of their traditional geographic ranges and, in some cases, pushed them right up to the brink of extinction.

So, when did the importance of predators in biotic communities begin to be recognized? One significant landmark was a paper published in The American Naturalist in 1960 by Nelson Hairston, Frederick Smith and Lawrence Slobodkin. The paper, entitled “Community Structure, Population Control, and Competition,” explored the idea that the sizes of herbivore populations in an ecosystem were not simply controlled by the abundance of vegetation, but that predator species were, in fact, extremely important in regulating the populations of the herbivores. Further, predator species via their impacts on herbivore numbers were important protectors of vegetation. “Why is the world green?” they were, in effect, asking. Their answer was because there were predators!

Experimental observations followed the publishing of the “Community Structure…” paper. A student of Frederick Smith, Robert Paine, conducted an experiment on the rocky shores of Washington State. A complex, intertidal community of barnacles, mussels and limpets also contained the predaceous starfish, Pisaster ochraceus. Paine removed the starfish from one section of the coastline and monitored the changes in the community.  After a year, the starfish’s primary prey, the barnacle Balanus glandula, had greatly increased in numbers in the starfish-less communities along with several fast growing mussel species. The species richness of the communities without the predator starfish, though, decreased from fifteen species to just eight! The predator was a keystone species that helped to maintain species richness and community stability.

Another early study looked at sea otters and the great kelp forests around the Alaskan island of Amchitka. Fur traders had decimated the sea otter populations in the waters around this island. The kelp forests, consequently, were overrun by sea urchins since there were no sea otters to prey upon them. The sea urchins overgrazed the kelp and thinned and degraded the entire vegetative community. The term “trophic cascade” was later applied to the destructive, rippling impact of the removal of a top predator throughout the trophic levels of a community.

Grey_wolves. Photo by R. MacDonald, Wikimedia Commons

The effect of a predator in a community can be quite subtle. Predators can influence the feeding patterns, behaviors and abundance of prey species even without any direct killing of the prey species.  An experiment with spiders (Pisaurina mira) and grasshoppers ( Melanoplus femurrubrum) showed the mere presence of the spiders (their mouthparts were sealed shut in the experiment) could cause the grasshoppers to forego feeding in some cases to the point of starvation. Consequently, the grasses in the systems which contained the non-feeding spiders, flourished! Fear of the predators generated a “behavioral trophic cascade” (also called a “fear cascade”) that allowed the community to stabilize and flourish.

Fear cascades also explained the observations on nesting behaviors and clutch sizes in song sparrows (Melospiza melodia) when recordings of racoons or predaceous birds were played near the nesting sites. Clutch sizes decreased by 40% when these auditory clues of a predator’s presence were played. This paper was published in Science in 2011.

The removal of a large predator also allows small to medium sized predators to greatly increase in numbers. I discussed this in a previous blog (Signs of Spring 11, May 16, 2019). These small predators can have devastating impacts on small mammal, bird, reptile and amphibian populations and can greatly disrupt the diversity and stability of an ecosystem.

Radio_collared_gray_wolf_on_snow. Photo by USFWS, Public Domain

Wolf re-introductions in New Mexico and Arizona (Mexican gray wolf) and Yellowstone National Park (gray wolf) have had expected impacts on prey herds and vegetative ecosystems. Red wolf re-introductions in North and South Carolina have had limited ecological impacts because of habitat fragmentation, coyote predation and interbreeding, vehicle collisions and uncontrolled poaching. The red wolf population in this area went from 130 individuals in 2000 to just 10 individuals in 2010.

Putting a large predator back into a biotic community is a complex task. The quality of the habitat, the new nature of the area’s climate, the presence of invasive plants and animals, and the response of potential prey species to the presence of a predator about whom they have grown quite naïve and just a starting list of factors to consider and evaluate. Also, the presence and proximity of humans (who are often referred to in the ecological literature as a “hyper-keystone species”) also will change the behaviors and potential success of re-introduced predators. People have to be included in the biotic community matrix in order to predict the outcomes of large predator re-introductions.

I will keep you updated on the Colorado wolves! Keep your paws crossed that they succeed!

Wasted food. Photo by Foerester. Wikimedia Commons

(Click on the following link to listen to an audio version of this blog …. Plastics

Deborah and I have had the same New Year’s Resolution for the past 15 years: don’t waste food! Making sure that we make meal portions that we can eat and making sure that we eat leftovers for dinner and/or lunch was essential. As little food waste as possible was our goal.

This year, in solidarity with the State of Colorado’s ban on single use plastic bags (a law that went into effect on January 1, 2024), new data on the ubiquity of plastic waste in our surroundings and disturbing news stories about how recycling centers were actually sending most “recycled” plastics to landfills, we also resolved to cut down on our use of plastics.

Bakelite bangles. Photo by Izzy. Wikimedia Commons

Plastics, as we have discussed several times in this blog space,  are human manufactured materials. They were invented 117 years ago (the first plastic was “bakelite” invented by Leo Baekland in New York in 1907). Plastics are large polymers of repeating organic subunits with very high molecular weights and, depending on the specific building block subunits, a wide range of properties and uses. Most of the building blocks of plastics come from petroleum or natural gas.

Roland Geyer (University of California, Santa Barbara) in a paper published several years ago in Science Advances (July 19, 2017) estimated that since the invention of bakelite we have produced 8.3 billion tons of plastics. Since we make almost 400 million tons of new plastic every year, by now our total tonnage is probably closer to 10 billion tons! That is enough plastic to cover the entire country of Argentina more than ankle deep in plastic materials. Geyer also notes that almost all of this plastic is non-degradable and will, along with all of the rapidly accelerating yearly production of new plastics, be with us for hundreds of years.

Most plastics end up in landfills but many millions of tons a year pollute our oceans, lakes and streams, land masses, and food webs. They are even part of the pollution load in the atmosphere! We are conducting an unintentional, unregulated, global experiment in which we are covering the Earth in plastic and also feeding it to a wide range of birds, fish and mammals (even ourselves!). The world’s oceans contain 150 million tons of plastic, and it is predicted that by 2050 there will be more plastic, by weight, in the oceans than fish.

Mountain of plastic. Photo by Jar-o, Flickr.

Many species of sea birds are known to eat and accumulate plastics. A recent study, published in the Journal of Hazardous Materials (May 15, 2023) noted that sea birds (in this case the flesh-footed shearwater  (Ardenna carneipes)) develop a very distinctive pattern of mucosa and submucosa scarring in their stomachs when they ingest plastics. This syndrome has even been given a name: “plasticosis.”

Plastics out in our environment can be in large, macro-sized forms (like the ocean-transported, plastic debris that I wrote about that befouls the beaches of the uninhabited Henderson Island out in the middle of the Pacific Ocean (Signs of Fall 4, Sept.5 2017).

Even more insidiously, though, plastics can be suspended and transported in both freshwater and marine systems in the form of microscopic pieces. These pieces are classified as micro-plastics (“MP’s”) (which are about 2 micrometers in size) or nano-plastics (“NP’s”) (which are about 500 nanometers in size).  In the water these particles get coated with algae and attract zooplankton and larger consumers (like sea birds and marine mammals).  The surfaces of these plastic particles also attract and accumulate a myriad of extremely toxic pollutants (including heavy metals, dioxins, PCB’s, DDT’s, and PAH’s) which then bioaccumulate in the organisms that ingest the plastic materials.Nano-plastics also are found in our foods and beverages.

Photo by Jm51. Wikimedia Commons

I talked about the prevalence of NP’s in beer and sea salt in Signs of Fall 12 (November 22, 2018), and a recent paper in the Proceedings of the National Academy of Sciences (January 8, 2024) looked at the amount of MP’s in bottled water (100,000 MP particles in every liter!). This paper also discussed some of the possible consequences of ingesting these MP’s including an increased incidence of colorectal cancers (especially in young people) and increases in Crohn’s disease and ulcerative colitis.

Another paper published last year in the Journal of Hazardous Materials (January 15, 2023) determined that humans consume about 5 grams of MP’s per week. These MP’s alter the community of colonic microorganisms (decreasing several beneficial microbes and increasing several pathogenic microbes). These MP’s are also absorbed into the body and found circulating in the blood stream and accumulating in a number of organs of the body (including the liver, spleen, lungs and placenta).

Another study published in Cell Reports (April 4, 2023) showed that NP’s in the diet triggered the activation of gut macrophages and stimulated the synthesis of an intestinal cytokine (Interleukin 1 (IL-1)). IL-1 acts to modulate the activity of the immune system and regulate inflammation. This “gut” IL-1 entered the blood stream and was detected in the brains of study animals where it stimulated microglial activity and activated the helper T-cell, Th17. Th17 produces an array of cytokines that trigger immune reactions to infectious agents (like bacteria). They also are significant immune modulators in a number of autoimmune diseases. The impact of this IL-1 and Th17 activity in the brain was a notable decline in cognitive and short-term memory.

And, a paper just published in the New England Journal of Medicine (March 7, 2024) examined the plastic content (MP’s and NP’s) of the fatty plaque removed from patients’ carotid arteries. Those patients with the highest amounts of plastics had significantly greater chances of stroke, heart attack or death from any causes during the follow-up months after the operation than those patients who had no plastic in their fatty plaque.

You don’t want plastics in your body!

Singl use plastic bages. Photo by Divotomezove. Wikimedia Commons

So, what have Deborah and I done to reduce our use of plastics?

1. We now buy our orange juice as frozen concentrate instead of ready-to-drink juice in plastic jugs.
2. We now only buy milk in half-gallon, cardboard containers instead of the gallon, plastic jugs.
3. We only buy eggs in cardboard egg cartons.
4. We stopped buying lettuce and other salad veggies pre-packaged in plastic containers. Now we buy loose produce and bring it home in our re-useable, cloth bags.
5. We buy bulk kitty litter from the local pet store and fill-up our reuseable litter pail as needed.
6. We buy meat and chicken etc. directly at the meat counter and get it wrapped in paper.
7. We buy yogurt in as large a container as possible instead of whole slew of small containers.
8. We continue to use our re-useable water bottles and also our reuseable grocery/shopping bags.
9. If we have soda, we buy it in recyclable, aluminum cans instead of plastic bottles or jugs.
10. Laundry soaps, dishwasher detergents, shampoos and contitioners are now available in paper packed and bar forms. No plastic bottles!
11. When we go to a restaurant, we take our own, reuseable containers for any leftovers.

It is hard to completely eliminate plastics from your life, but we are working toward a more sustainable home ecosystem!

By the way, the new Colorado law banning the distribution of single use plastic bags is being widely ignored by many of the stores in our area! There are still thousands of available bags at the checkouts of our grocery stores and for delivery of take-out food from restaurants. Things change, but slowly!

E. coli at 1000x. USDA. Public Domain

(Click on the following link to listen to an audio version of this blog … Human microbiome (1)

Studies of the microorganisms that live on and in the human body have been going on since that late 19^th Century. Escherichia coli was first isolated from the colon and described in 1888. Bifidobacteria was described in 1892. The beneficial influences of gut microorganisms were being discussed in 1900, and the specific impacts of microbially generated metabolites in the colon were subsequently outlined.

Technical innovations in the past 25 years, though, have made the study of our microorganisms (i.e. the “human microbiome”) much more precise and also quicker and easier to accomplish. In particular, methods analyzing the nucleic acid (DNA and RNA) sequences in sample materials (feces, tissue scrapings, sweat, tears, skin oils etc.) and relating these nucleic acids to specific  bacteria, fungi, archaea and viruses have allowed the wide-spread exploration and description of the human microbiome. These culture-independent methods have led to an explosion of ideas, studies and published papers.

At first, the number of cells in the human microbiome was thought to be some 10 to 100 times the actual number of cells in the human body. More precise studies, though, indicate that numerically there are probably about the same number of microbiome cells (about 38 trillion) as there are cells in all of the tissues and organs of a human being (about 30 trillion cells). The genetic information contained in these two groups of cells, though, is several orders of magnitude different (the human genome consists of 20,000 genes while the collective genomes of the human microbiome contains 2,000,000 genes).

A large number of factors influence the structure of a person’s microbiome. Hygiene, probiotics, prebiotics, overall diet, antibiotics, disease, exercise and age all alter the microbial community of the microbiome. One of the most remarkable insights from the microbiome research of the past 25 years has been the realization that every individual has their own unique microbiome community! The search for a “core” microbiome common to all humans has not been successful!

Coevolition of human microbiome. G. Berg et al. Wikimedia Commons

This lack of a core microbial community makes studies exploring the impact of diseases on the body’s microbial community (or, to reverse that thought, studies on how particular aspects of the body’s microbial community might affect (or cause) disease) very difficult. If everyone has a unique microbiome, changes due to or causing illness become very hard to reliably detect or describe!

There is, though, a generalized response of the gut microflora to inflammation not only in the colon but anywhere in the body. Inflammation decreases the number and diversity of colonic microorganisms which may, then, affect other organ systems of the body.

There are a number of diseases that appear to have connections to the human microbiome: Type 2 diabetes, obesity, inflammatory bowel diseases (Crohn’s Disease and ulcerative colitis). Parkinson’s Disease, depression and several types of cancer. It is not clear, though, if these connections are causal or if they are simply correlations to changes in the body’s homeostasis due to the disease..

Human newborn. Photo by Ernest F. Wikimedia Commons

The human microbiome begins to form at birth. A new-born infant acquires microbial symbionts from their mother and from their immediate environment. Vaginally delivered newborns are well bathed in microbial-rich secretions from their passage down the  birth canal. Caesarian-delivered newborns are not heavily exposed to maternal microbial populations and are much more active in acquiring microbes from other areas of their environment. A paper published in Nature (October 3, 2019) found that C-section newborns had colonic microbiomes that were up to 30% hospital-acquired bacteria (including a number of opportunistic pathogens)! Breast-fed infants, however, whether they were birthed vaginally or via Caesarian-section,  acquire significant microbial symbionts from their mothers.

Differences between the microbiomes of vaginally-delivered and C-section infants disappear by one year of age. During this first year of life, though, there can be significant differences in an infant’s metabolic activities depending on what type of microbiome they possess. In the first year of life the immune system undergoes significant changes and steps in its maturation cycle, and the infant’s microbiome seems to play a significant role in these immune system modulations. The higher rates of asthma and allergies in children who were C-section babies are important observations that support the idea that the altered microbiome in C-section infants acts to inhibit normal immune activity. C-section babies also have higher rates of Type 1 diabetes which may reflect another level of immune disfunction.

Baby and basset hound, Photo by Gmip. Wikimedia Commons

The Hygiene Hypothesis states that children not exposed to normal infant diseases, environmental debris and immune triggers are more likely to have underdeveloped (“uneducated”) immune systems. These children have higher rates of asthma, eczema, and allergies. It is possible that that system that is at least in part mediating this Hygiene Hypothesis impact is the infant’s microbiome. If an infant is exposed to an abnormally sterile environment, they will not be able to construct a normal microbiome.

The onset of the COVID-19 Pandemic had huge impacts on many aspects of our biological, social and economic worlds. In a study recently published in Scientific Reports (August 16, 2023) a research group in New York City monitored the development of infant microbiomes in 54 children born at onset of the pandemic. Pandemic restrictions in New York City were very severe, and all of these newborns were kept quite isolated from contact with anyone who was not in their immediate family. This very unnatural restriction in contact with other people had a remarkable impact on the microbiomes of the infants. Overall, the diversity of their microbiomes was significantly decreased from previously measured “normal” levels. Future studies on these children are needed to determine if they have a greater propensity toward asthma, allergies and other immune system disorders.

The human microbiome has been recognized and studied for over 100 years. Recent technological breakthroughs that enable researchers to make culture-independent analysis of the microbiome has led to an explosion of studies and published papers. There are, though, many fundamental things about the human microbiome that we do not know. Is their a “human core” of microbial species that define all human microbiomes? Are there ways to get “good” microbial species established in the human colon? Are there ways to encourage “good” microbial species in the colon to proliferate? And, which microbial species in the human colon are “good,” and what exactly do they accomplish in the body?

Lot’s of really great questions!