When examining population ecology, a common story comes to mind.  Imagine a habitat   with endless resources, and no predation or competition. It sounds like this would be ideal for sustaining population. What could possibly go wrong? This type of environment is the perfect breeding ground for the overpopulation of any species. If a population has enough food to sustain and thrive, exponential breeding will occur. For several generations this growth will not be a significant problem. However, soon there won’t be enough food to sustain the entire population. Food becomes scarce, and individuals begin to compete for limited resources. Only the most fit of the individuals will survive, while the weak will die off due to disease and starvation. The population will plummet drastically, leaving only several individuals left. This cycle is related to the carrying capacity of a species, which is the size of the population that can be sustained indefinitely. By exceeding this limit, the clock starts to tick until disaster strikes.The debate around genetically modified organisms (GMO) is huge and heated on either side. One of the major considerations when arguing against the use of GMO products is the potential for environmental harm. First of all, it is important to understand what a GMO is precisely. The World Heath Organization defines them as organisms whose DNA has been altered in a non-natural way. GM plants are usually changed to be insect resistant, virus resistant, or herbicide tolerant. With these changes come some potentially problematic environmental challenges.

Firstly, toxicity is a huge issue surrounding chemical pesticides and herbicides, used commonly with GMOs, in addition to the toxicity inherent to these plants. GMOs may be toxic to non-target organisms, bees and butterflies being the most talked-about examples currently. Bees are hugely important in the pollination of many food crops, but are unfortunately extremely endangered by modern agricultural techniques, such as GM crops. Monarch butterflies are specifically at risk from GMO maize plants. In addition to bees and butterflies, birds are also at risk from pesticides, and work as biological control agents and pollinators, again, like bees.

Furthermore, the longterm effects of GMOs are not certain. Pests that are targeted by these agricultural methods can adapt to pesticides and herbicides, in addition to the DNA changes in GM plants to make them ¨resistant.¨ This means that they will not always be effective, but their toxic legacies will remain.

Cumulative effects of products such as GMOs are important to take into consideration. Evidence also suggests that small genetic changes in plants may produce even larger ecological shifts, meaning that there is potential for GMO´s to become persistent and weedy in agricultural conditions, since they are modified to be resistant to some modern agricultural techniques. This can also mean being invasive in natural settings, where GMOs, of course, do not occur naturally. It is not impossible for new, human modified, plants to become invasive species in delicate, natural ecosystems. 

Finally, biodiversity, while it is critical in all ecosystems and to the sustainability of all species, is put at risk by GMOs. When GM crops are planted, generally in a monocrop fashion, many heritage seeds are no longer used. The nature of GMOs means fewer weed flowers and, therefore, less nectar for pollinators. Toxins released into the soil through the plants´ routes mean fewer soil bacteria, which are integral to healthy soil for plants to grow without the use of chemical fertilizers. Toxic residues are left in the soil of GM crops. Nutrients are not returned to the soil in mono crops and from GMO foods, meaning that soil is becoming dry and void of all nutrients, generally integral to the growing process. A cycle of dependence on GMO seeds and chemical fertilizers, pesticides, and herbicides is then created in order to grow a single crop. In addition to soil issues, the irrigation used to grow GM foods naturally carries all of these problems into water sources and into the air. This exposes different bacteria, insects, and animals to the same problems.

All of these impacts must be taken into consideration in the larger picture; GMO´s DNA may end up in soil, compost, animal feed and byproducts, and other living organisms from insects to larger pests. Bees can transport pesticides, herbicides, and DNA through the air into the environment. Once a plant is introduced in an agricultural environment, it is reasonable to assume it will become part of a larger ecosystem, meaning the problem of environmental damage done by GMOs is much larger than simply potentially harming our health.

Aside from environmental issues, GMOs are the topic of social and ethical debates as well. It goes without saying that we live in an inter-connected world, where the way we interact with nature can cause a complex array of consequences. Being informed on the food we are consuming, and the way modern agricultural techniques are affecting the environment, is one effective way of consciously interacting with the natural world.

Debate on GMO

Genetic Engineering-sites at PSU

Impact of GMO

Last week over spring break I had the amazing opportunity to go diving off the shores of Turks and Caicos and it was truly one of the most breathtaking sights I have ever experienced. I also have the pleasure of taking the SCUBA kinesiology class here at Penn State and have learned a little bit about the different environments divers encounter. Specifically, diving in the caribbean and warmer water is more popular, and these areas are homes to millions of species, including coral reefs.

The number of healthy coral reefs is diminishing at an alarming rate and it is something that could change the way thousands of underwater species live.

Why are coral reefs being threatened?

The majority of reef loss or damage is not deliberate. Coral reefs are being degraded by an accumulation of stresses arising from human activities. In simple terms, stresses can be grouped by the actions of people extracting material from, and placing materials upon, coral reefs. Overfishing, pollution and coastal development top the list of chronic stressors. In many situations chronic stresses are overwhelming the resilience, (or the capacity for self-repair), of reef communities. Some coral reefs are covered with sand, rock and concrete to make cheap land and stimulate economic development. Others are dredged or blasted for their limestone or to improve navigational access and safety. In addition to this, long-term changes in the oceans and atmosphere (rising sea temperatures and levels of CO2), and acute stresses from highly variable seasons, severe storms, earthquakes and volcanic eruptions also affect coral reefs.

What are we doing to damage coral reefs?

• Overfishing: Increasing demand for food fish and tourism curios has resulted in over fishing of not only deep-water commercial fish, but key reef species as well. Overfishing of certain species near coral reefs can easily affect the reef’s ecological balance and biodiversity. For example, overfishing of herbivorous fish can also lead to high levels of algal growth. From subsistence level fishing to the live fish trade, inadequate fisheries management is forcing the decline of fish stocks. Choose seafood products that come from certified, well-managed and sustainable fisheries. Certified products are available at most supermarkets.
• Destructive fishing methods: Fishing with dynamite, cyanide and other methods that break up the fragile coral reef are highly unsustainable. Dynamite and cyanide stun the fish, making them easier to catch. Fishermen say they have no other option if they are to compete with trawlers and overcome a smaller supply of fish because of previous overfishing. These practices generally do not select or target particular fish species and often result in juveniles being killed in the process. Damaging the coral reef habitat on which the fish rely will also reduce the productivity of the area, with further impacts on the livelihoods of fishermen.
• Unsustainable tourism: Tourism generates vast amounts of income for host countries. Where unregulated however, tourism pressures can cause damage to the very environment upon which the industry depends. Physical damage to the coral reefs can occur through contact from careless swimmers, divers, and poorly placed boat anchors. Hotels and resorts may also discharge untreated sewage and wastewater into the ocean, polluting the water and encouraging the growth of algae, which competes with corals for space on the reef.
• Coastal development: The growth of coastal cities and towns generates a range of threats to nearby coral reefs. Where space is limited, airports and other construction projects may be built on land reclaimed from the sea. Sensitive habitats can be destroyed or disturbed by dredging activities to make deep-water channels or marinas, and through the dumping of waste materials. Where land development alters the natural flow of water, greater amounts of fresh water, nutrients and sediment can reach the reefs causing further degradation. Within the last 20 years, once prolific mangrove forests, which absorb massive amounts of nutrients and sediment from runoff caused by farming and construction, have been destroyed. Nutrient-rich water causes fleshy algae and phytoplankton to thrive in coastal areas in suffocating amounts known as algal blooms. Coral reefs are biological assemblages adapted to waters with low nutrient content, and the addition of nutrients favours species that disrupt the balance of the reef communities.
• Pollution: Coral reefs need clean water to thrive. From litter to waste oil, pollution is damaging reefs worldwide. Pollution from human activities inland can damage coral reefs when transported by rivers into coastal waters. Do your bit – do not drop litter or dispose of unwanted items on beaches, in the sea, or near storm drains.
• Global Aquarium Trade: It is estimated that nearly 2 million people worldwide keep marine aquariums. The great majority of marine aquaria are stocked with species caught from the wild. This rapidly developing trade is seeing the movement of charismatic fish species across borders. Threats from the trade include the use of cyanide in collection, over-harvesting of target organisms and high levels of mortality associated with poor husbandry practices and insensitive shipping. Some regulation is in place to encourage the use of sustainable collection methods and to raise industry standards.

How are coral reefs affected by climate change?

• Coral Bleaching: Coral bleaching occurs when the symbiosis between corals and their symbiotic zooxanthellae breaks down, resulting in the loss of the symbionts and a rapid whitening of the coral host (thus the term “bleaching”). This is a stress response by the coral host that can be caused by various factors, but more severe and frequent cases are being caused by a rise in sea surface temperature (SSTs). If the temperature decreases, the stressed coral can recover; if it persists, the affected colony can die.
• Rising sea levels: Observations since 1961 show that the average temperature of the global ocean has increased even at depths of 3000m (IPCC report), and that the ocean has been absorbing more than 80% of the heat added to the climate system. Such warming causes sea level rise and creates problems for low lying nations and islands.
• Ocean Acidification: This is the name given to the ongoing decrease in the pH of the Earth’s oceans, caused by their uptake of anthropogenic carbon dioxide from the atmosphere. Although the natural absorption of CO2 by the world’s oceans helps mitigate the climatic effects of anthropogenic emissions of CO2, it is believed that the resulting decrease in pH, (i.e. making the water acidic), will have negative consequences, primarily for oceanic calcifying organisms such as coral reefs. 

How to help coral reefs

1. Conserve water: The less water you use, the less runoff and wastewater will pollute our oceans.
2. Help reduce pollution: Walk, bike or ride the bus. Fossil fuel emissions from cars and industry raise lead to ocean warming which causes mass-bleaching of corals and can lead to widespread destruction of reefs.
3. Research what you put on your lawn: Although you may live thousands of miles from a coral reef ecosystem, these products flow into the water system, pollute the ocean, and can harm coral reefs and marine life.
4. Dispose of your trash properly: Don’t leave unwanted fishing lines or nets in the water or on the beach. Any kind of litter pollutes the water and can harm the reef and the fish.
5. Support reef-friendly businesses: Ask the fishing, boating, hotel, aquarium, dive or snorkeling operators how they protect the reef. Be sure they care for the living reef ecosystem and ask if the organization responsible is part of a coral reef ecosystem management effort.
6. Plant a tree: Trees reduce runoff into the oceans. You will also contribute to reversing the warming of our planet and the rising temperatures of our oceans.
7. Practice safe and responsible diving and snorkeling: Do not touch the reef or anchor your boat on the reef. Contact with the coral will damage the delicate coral animals, and anchoring on the reef can kill it, so look for sandy bottom or use moorings if available.
8. Volunteer for a coral reef cleanup: You don’t live near a coral reef? Then do what many people do with their vacation: visit a coral reef. Spend an afternoon enjoying the beauty of one of the most diverse ecosystems on the Earth.
9. Contact your government representatives: Demand they take action to protect coral reefs, stop sewage pollution of our oceans, expand marine protected areas and take steps to reverse global warming.
10. Spread the word: Remember your own excitement at learning how important the planet’s coral reefs are to us and the intricate global ecosystem. Share this excitement and encourage others to get involved.

What can I do to protect coral reefs?

Reefs are at risk

Coral Reefs and Climate Change