Question

In our discussion of coral reef. Explain how the human impact has impacted the coral reef. a) What trait might be selected for in the coral population that would allow for adaptation to the impacts caused by human? (i.e. what selection pressure might their be?) b) What type of interspecific interactions describes the interaction within the coral AND the coral reef?

Answer 1

Impact of human on Coral reefs

Human impact on coral reefs is significant. Coral reefs are dying around the world. Damaging activities include coral mining, pollution (organic and non-organic), overfishing, blast fishing, the digging of canals and access into islands and bays. Other dangers include disease, destructive fishing practices, and warming oceans. Factors that affect coral reefs include the ocean's role as a carbon dioxide sink, atmospheric changes, ultraviolet light, ocean acidification, viruses, impacts of dust storms carrying agents to far-flung reefs, pollutants, algal blooms, and others. Reefs are threatened well beyond coastal areas. Climate change, such as warming temperatures, causes coral bleaching, which if severe kills the coral. Reefs in close proximity to human populations are subject to poor water quality from land- and marine-based sources. In 2006 studies suggested that approximately 80 percent of ocean pollution originates from activities on land. Pollution arrives from land via runoff, the wind, and "injection" (deliberate introduction, e.g., drainpipes). Runoff brings with it sediment from erosion and land-clearing, nutrients and pesticides from agriculture, wastewater, industrial effluent, and miscellaneous material such as petroleum residue and trash that storms wash away. Some pollutants consume oxygen and lead to eutrophication, killing coral and other reef inhabitants.

Species which adapt Climate

The researchers exposed two threatened Caribbean reef-building coral species, staghorn coral (Acropora cervicornis) and mountainous star coral (Orbicella faveolata), were exposed to combinations of normal (26 degrees Celsius) and elevated temperature (32 degrees Celsius) and increased carbon dioxide levels (pH 7.8/800 ppm) for nine weeks. Genetic and physiological data such as skeletal growth was then collected on the corals to determine if stress events are recorded in a coral's skeletal history.

At the end of the nine weeks, any corals that were still surviving were recovered at the cool temperature and normal pH to determine the capacity of these corals to bounce back once environmental conditions became more hospitable as naturally occurs as summer transitions into fall.

The study found that some corals in the normally cool waters of the Cook Islands carry genetic variants that predispose them to heat tolerance. This could help the population adapt more quickly to rising temperatures. But the preliminary results show they may not adapt quickly enough to outpace climate change. In previous work, the researchers identified genes that make some individual corals more heat tolerant than others. In the current study, they found these warm water variants in corals in the Cook Islands, at low levels. Reef-building corals are among the most vulnerable organisms to rising ocean temperatures. Over the past three years, coral reefs have experienced the worst bleaching and mortality events in recorded history, largely due to warmer waters.

Interaction in Coral Reef community

Symbiotic Relationships exhibited on the Reef:
The coral reef ecosystem is a diverse collection of species that interact with each other and the physical environment. The sun is the initial source of energy for this ecosystem. Through photosynthesis, phytoplankton, algae, and other plants convert light energy into chemical energy. As animals eat plants or other animals, a portion of this energy is passed on and the energy is recycled. Figure 4 demonstrates the flow of energy through the reef community. The coral reef ecosystem is a diverse collection of species that interact with each other and the physical environment. The sun is the initial source of energy for this ecosystem. Through photosynthesis, phytoplankton, algae, and other plants convert light energy into chemical energy. As animals eat plants or other animals, a portion of this energy is passed on.