06/18/04
Q: Please describe the characteristics of healthy coral, sponges, and anemones. What are some of the factors that increase and/or decrease the presence of such sea life? Is there a rare type of coral, sponge, or anemone you look for when exploring off the southeast states?
A:
The most obvious characteristics scientists look for to determine
health are: color and how much sediment (mud and sand) has settled
on an animal. Just like when people are sick and they become pale
or sallow, the brilliant
colors marine animals often sport tend to fade in unhealthy
individuals. Lophelia
coral, on the other hand, is bright white when healthy and
turns brown when it is sick or dead. Animals that are sick also
tend to move more slowly. Sediment builds up on these sluggish
critters and a coating of mud or sand can indicate an unhealthy
specimen.
Temperature,
current strength, and the quantity of hard surfaces onto which
creatures can attach themselves determines the abundance of corals,
sponges, anemones, and other sea life. Different species require
different temperatures. Since the temperature of the ocean generally
decreases as you go deeper, warmer water species tend to be closer
to the surface than those who prefer cooler temperatures.
Currents
are also important to corals, sponges,
and anemones since they are
stationary and rely on water currents to bring them food (unless
they live on a hermit crab's shell!). If the current is strong,
it can move more plankton within reach of the organism. If the
current is weak, the organism might not get enough food and could
easily die.
These
animals also need to attach themselves to a hard structure. Areas
with rocky bottoms and hard corals (as opposed to soft corals)
are more likely to host abundant life. Before each dive the ship
uses an echosounder to map the rock formations on the bottom.
The more ridges and peaks there are, the more likely we are to
see marine life during a dive.
Information is limited about the organisms that exist deep in the Atlantic Ocean and the scientists on this mission are conducting a general survey of the marine life within our study area. They don't yet know which species are rare and which are common. At this point, they are taking as many samples as possible in order to document the abundance of each species, with an eventual goal of determining which organisms are rare and which occur frequently.
