Koch Key Blog
Scott Pescatore & Taylor Derrico
Koch Key was our first stop on our on our first day in the keys. Koch Key is a mangrove island surrounded by sea grass. The three different types of sea grass that surrounded the island are the shoal grass (Halodule wrightii), manatee grass (Syringodium filiforme), and turtle grass (Thalassia testudium). The sea grass is a habitat for some species of organisms including fish such as the bucktooth parrot fish (Sparisoma atomarium). There were algae amongst the sea grasses such as the genus Halimeda, Batophora, Penicillus, and Caulerpa. There was only one type coral spotted at Koch Key and it is the smooth star coral (Solenastrea bournoni). The reason there was so few algae and corals in the area was because the mangrove island casted shade over the area not allowing the sea grass and algae to grow immediately near it. This combined with grazing from herbivorous fish such as the rainbow parrot fish (Scarus guacamaia) and the queen parrot fish (Scarus vetula) created a sandy bottom under the mangroves. The coral was found on the sandy bottom away from the shade where it was allowed to grow. The mangroves provided structure that was a suitable habitat for larger fish such as mangrove snapper (Lutjanus griseus), lane snapper (Lutjanus synagris), schoolmaster snapper (Lutjanus apodus), and the great barracuda (Sphyraena barracuda). The structure provided a habitat for more fish which created a larger biodiversity within the fish. Other organisms that resided within the mangrove structure were Sargent Majors (Abudefduf saxatilis), spiny lobster (Pahulirus argus), nurse shark (Ginglymostoma cirratum), pork fish (Anisotremus virginicus), lionfish (Pterois volitans), sea bream (Archosargus rhomboidalis), sheepshead (Archosargus probatocephalus), blue striped grunt (Haemulan sciunus), and four eyed butterfly fish (Chaetodon capistratus).
The water was less turbid at Koch Key because there was flowing water that would wash away the decaying material from the mangroves that would cause more detritus to be in the water. This detritus would typically make a mangrove island smell bad and cause the water to be more turbid, but because the flow of the water washes it away there is no decaying smell. Because the water is less turbid, it allowed more sunlight to penetrate the water which made it more habitable for sea grass and macro algae to grow around the island. The sea grass and macro algae around the island are important because they can be used as a food source for some organisms. The sea grass provides habitat for smaller organisms to allow for more biodiversity. Also, a temperature flux was present in the habitat due to the mangrove island being on the gulf side of the keys. A seasonal temperature flux can be observed due to the shallow water not being able to hold heat as well as a large body of water like the Atlantic Ocean. The area would be colder during the winter months, and warmer during the summer months. The turbidity of the area can be influenced from the freshwater flowing into the Florida bay from the everglades. The freshwater carries sediment and nutrients which will cause the turbidity to be higher, but because of the constant flow of water this will only be a temporary affect.
The environment at Koch Key was different from the other two sites we visited that day. The other two environments were old damn bank and old sweat bank. These environments were shallow and didn’t provide a lot of structure. They had fast flowing water, and more diversity in macroalgae. Each spot also produced less fish species because of lack of structure. The species that were spotted were benthic species. The high flow rate of water and the lack of structure made it a great place for macroalgae to grow. There was also a lot of sea grass present at Koch Key, but it was shorter due to the faster flow of water. The fast flow of water kept the turbidity at the next two locations low just like at Koch Key. There was no shade at the two banks so it allowed for the macro algae and grass to grow where ever it wanted unlike at Koch Key. The environment at Koch Key was very different than the environments at Old Dam Bank and old sweat bank.