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Red Grouper Habitats in Florida Bay
Red grouper are known to excavate under hard objects and keep hardbottom areas clean of sediment and debris. We observed a diverse ecological community in the immediate vicinity of the red grouper holes, including lobsters, crabs, shrimp, anemones, corals, and numerous fish species. Sea grasses and algae were observed a few meters away from the holes. Similar red grouper habitats have been observed in deep water (80 m) near the shelf edge, where we have collected sidescan-sonar imagery and views with a video camera mounted on an ROV. The larger red grouper at these sites are a heavily targeted commercial and recreational fishery species. What happens to the benthic biological community living around a red grouper hole if the red grouper is removed? How quickly does sediment fill the hole? Do the other species leave? Are the red groupers the only residents moving the sediment? Does groundwater seepage play a role? Because it is much easier to make observations and 'manipulate the ecosystem' in 3 m of water than in 80 m, these questions are being tackled first in Florida Bay before applying what we learn to the deeper, less accessible red grouper habitats. Kathy reports, "Although we had permits to kill the grouper, we did not. We experimented with caging them out of their hole or caging them in a place with no hole to see what they would do and how quickly. The cages are about 4'x4'x2' and allow free movement of smaller species through them. We intended to leave the grouper caged for no more than 2 weeks, but a little hurricane got in the way of the release trip. I think they ended up caged for 3 or 4 weeks, but seemed to be OK." The Marine Conservation Biology Institute (MCBI) funded the work as a pilot study to assess the feasibility of a larger, better-controlled project. The MCBI is a national nonprofit tax-exempt organization dedicated to advancing the multidisciplinary science of marine conservation biology. Felicia Coleman is presently writing a proposal to seek additional funding.
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in this issue: Florida Bay Red Grouper
cover story: |