While I was at the California Academy of Science, I ran into a friend from high school. She was cleaning the Philippine Tank while Scuba Jason was giving the informational talk about the coral reef. After she was done, I was able to talk to her and found out that she is studying marine biology and has a love for the coral reef. I was able to interview her and below is our conversation.
Q: When did you first become interested in coral reefs?
A: As a kid watching nature documentaries, I fell in love with coral reefs. But I have always been interested in the ocean and the amazing creatures that make a living in its depths.
Q: In Cordell Bank, how diverse is the ecosystem of the coral reef?
A: The ecosystem in Cordell Bank is very diverse. It is such an important system that it was designated a marine sanctuary in 1989. Underwater there is everything from coralline algae and anemones to octopus fish and marine mammals. Above the water seabirds can be found feeding on the bait fish that congregate here during upwelling pulses.
Q: What are some of the threats that could effect the coral reef ecosystem?
A: There are numerous issues facing coral reefs today. These threats include ocean acidification (OA), temperature increases, overfishing, wildlife trade, eutrophication and coastal development. Hard corals are build calcium carbonate skeletons and provide the reef with structure. As the ocean becomes more acidic coral skeletons become harder and harder for coral polyps to build due to the imbalance in the water chemistry. It is also possible that the skeletons will dissolve as the ocean continues to acidify. Additionally OA impacts the base of the food web in the ocean. Small crustaceans that make up the bottom of the food web are facing the same problems as corals which will have major implications for the rest of the ecosystem. Increasing temperatures are a problem for corals because their symbiotic algae (zooxanthellae) have very narrow physiological tolerances and require specific temperatures. When the water gets too hot the zooxanthellae either leave the coral or are expelled by the coral. This loss of zooxanthellae results in coral bleaching. Zooxanthellae provide 80-90% of the nutrients they produces to the coral so losing them is a big problem for the corals. Eutrophication and coastal development are also problems for coral reefs. Corals require clear water for their symbiotic algae to be able to photosynthesize. Eutrophication is the process of increasing the chemical nutrients available in an ecosystem. Eutrophication and subsequent algae blooms is typically caused by agricultural runoff that is loaded with nutrients that are beneficial to plants. Algae blooms not only cloud the water (making photosynthesis for zooxanthellae more difficult), certain species of algae can over grow and kill stressed corals. Coastal development is also an issue for corals because sediment is often released which smothers the coral and kills it. This is why capturing runoff from constructions sites is so important for reducing human impacts on aquatic ecosystems, because anthropogenic sediment runoff is a problem for more than just corals. Overfishing is a big problem in the ocean and impacts the coral reef ecosystem in many ways. Typically humans target the largest predatory fish species, overfish those species and then move on the next largest fish (which is smaller). This process is called fishing down the food chain. Ecosystems function through very a complicated network of interactions between species. The food web is also a complicated system where predator and prey relationships shape the abundance of various trophic levels (predators are at the top trophic levels and plants are at the bottom tropic level). If you have more predators then they will eat more prey species. When top predators are removed from the system the balance is upset so much so that the bottom of the food web is significantly impacted. We call this a tropic cascade. So how does this all relate to corals reef? By removing the top predators from a coral reef system there will be consequences for the primary producers at the bottom of the food web. This happens because top predator abundance indirectly influences the grazer composition at the bottom of the food web: fewer top predators, more grazers eating the primary producers. The wildlife trade also impacts reefs by removing species from the wild to be sold by humans. For the aquarium trade wild fish and corals are removed from the reef and shipped all over the world to be pets in people’s aquariums. I have seen statistics that only 10% of fish survive the trip from reef to aquaria. This ties directly into the problem of overfishing. There are companies that breed commercially valuable reef fish and corals in order to take the pressure off wild systems. So if you want to have a tropical aquarium please PLEASE buy your corals and fish from breeders rather than the wild! Also wild organisms most likely carry parasites and disease that may destroy your aquarium, which is another reason to buy from a breeder. The Curio trade is another problem for coral reefs. People selling corals and shells as trinkets puts tremendous strain on these systems. In some cases whole coral reef ecosystems are scraped off the sea floor, broken down and sold as sold as trinkets. The value of a coral reef is not in how many earrings it can produce but how many thousands of species it supports and the countless ecosystem services it provides. Ecosystem services, like buffering the shore line form storm surge and providing a nursery for commercially valuable fish, are all provided for free by these amazing ecosystems. Deep ocean mining is an emerging concern for deep ocean reefs. These biological systems are some of the oldest and slowest growing systems on earth. There is a coral off the coast of Hawaii that is over 4,200 years old. Orange Roughy takes 30 years to reach sexual maturity, but is a commercially valuable fish. As humans improve the ability to extract precious metals and fish from the deep ocean, we also need to be aware of how our actions impact the ocean. Without proper management of these resources, humans can very quickly cause irreparable damage to systems we know very little about. We know so little about these systems that we have no idea how damaging them will impact the rest of the ocean.
Q: How does the Cordell Bank reef differ than other reefs?
A: Most people are familiar with tropical coral reefs that are found in shallow warm water at low latitudes. Images of crystal clear water and brightly colored corals and fish come to mind. These tropical reefs are powered by the sun through the symbiotic relationship between corals and zooxanthellae. Cordell Bank is different in that it is a deep water reef found in cold water with little sunlight. While many tropical reefs touch the surface of the water, the shallowest point on Cordell Bank is 115 feet deep. This system is powered by upwelling, where cold nutrient rich waters come up from the deep ocean and mix with warmer oxygenated and sunlight to create a system powered by phytoplankton (tiny algae and plants). Both temperate reefs, like Cordell Bank, and tropical coral reefs support a wide variety of plants and animals. Cordell Bank is dominated by coralline algae and anemones, while most tropical reefs are dominated by hard and soft corals.
Q: In sharing information about the ecosystem of coral reefs, what is the most important thing/things people should know about them?
A: Tropical coral reefs support 25% of the life in the ocean, and when the cold water reefs are included that number is much bigger. Reefs are vitally important to life in the ocean and need to be recognized and protected as important resources by international laws and individual consumers alike. Reefs are resilient when given a chance and likely hold many important yet-to-be-discovered pharmaceuticals. Healthy coral reefs are both ecologically and economically important.
This interview helped me with my guiding questions because I was able to understand how important the coral reef is to the world and was able to understand that coral reefs are not always located below the equator line like Cordell Bank.