Deborah Aller and Ian
Martin

Abstract

As one of the biggest providers of
environmental complexity in tropical marine ecosystems, it is crucial
that researchers continue to compile as much information as possible
about coral reefs and their high fragility, diversity, and
productivity. One of the biggest staples in the study of reefs and
their conservation is the balance between spatial partitioning
between algae and corals and the constant competition for limiting
resources, such as light. Since algae tends to grow and spread much
faster than reef building corals, herbivory by sea urchins,
specifically Diadema antillarum, is essential for maintaining
coral colonies and thus an array of environmental complexity. The
current study examines how D. antillarum grazing patterns are
affected by varying light/dark cycles as well as algal feeding
preferences of D. antillarum. Twelve D. antillarum were
divided in to groups of four and placed in three separate tanks which
received varying amount of light. Additionally each tank received
three different algal genera for grazing in equal amounts. Algal
samples were weighed and information was compiled to determine which
light treatment caused the urchins to graze more as well as which
algal genera was preferred by the urchins for grazing. It was found
that there was no significant difference in mean algal percent mass
consumption between the groups under differing light/dark cycles.
Similarly it was also found that the D. antillarum used for
this study had no feeding preferences based on the three algal genera
provided to them; Dictyota sp., Enteromorpha sp., and
Wrightiella blodgettii. Possible factors that may have
contributed to the gathering of skewed data which lead to
insignificant results could include but are not limited to a lack of
acclimation of the urchins to the testing tanks that were used, the
use of unfamiliar algal genera that are not normally a part of the D.
antillarum diet, and a natural homing behavior of sea urchins.
Because of limited supplies and time, further investigation is then
called for and more research is needed to solidify more concretely
the findings of this study.