Georgia
Dynamics of Benthic Marine Invertebrate Communities on Temperate
Offshore Reefs of Georgia
Principal Investigator: Daniel Gleason, Georgia Southern University Department
of Biology
ABSTRACT
Subtidal temperate reefs have received substantially less attention from the
scientific community than tropical coral reefs. This is somewhat surprising
considering that they may be no less important in promoting species diversity
and enhancing production. Similar to their tropical counterparts, however,
temperate reefs are in peril. Primary threats include commercial trawling,
recreational fishing, ocean acidification, and increased sedimentation. Clearly,
understanding the basic biology of these systems, including the ecological
processes that shape the benthic community is of importance. I propose to
investigate the community dynamics of sessile marine invertebrates occupying
hard substrata on offshore reefs of Georgia, including those in Gray’s Reef
National Marine Sanctuary (GRNMS). The specific objectives are:
A) To determine if succession in sessile benthic invertebrate populations
on subtidal hard bottom reefs progresses by a predictable sequence of
species replacements and culminates in a single climax community.
B) To determine if established communities of sessile benthic invertebrates
on individual subtidal hard bottom reefs vary both spatially and temporally.
C) To determine if sedimentation is a structuring force in the development
and maintenance of subtidal hard bottom reef communities of coastal
Georgia.
The first objective will be investigated by following succession on 30x30 cm plots
that have been cleared of all sessile benthic invertebrates. The power to
separate seasonal patterns of establishment and disappearance from longer
term trends will be high because the proposed investigation builds on a study
that has accumulated more than 2.5 years of similar data. The second objective
will be addressed at two hard bottom sites by quantifying sessile benthic
invertebrate populations 3 times each year in 0.25 m2 quadrats placed adjacent
to permanent 30 m long transects. Three transect lines will be established at
each site and will be deployed to encompass the gradations in community
composition that appear to occur across rocky ledges off Georgia. Finally,
the role that sediment plays in controlling succession and in contributing to
distributional patterns observed along hard bottom ledges will be addressed
correlatively by documenting variability in the rates of downward flux of
suspended particulate matter.
Completing the above objectives has practical implications for managing GRNMS
and addresses Sea Grant’s high priority research areas for understanding
biological processes in key ecosystems and habitats, understanding larval
recruitment processes, and understanding the delivery and distribution of
sediment in coastal ecosystems. Additionally, accomplishing all three of the
proposed goals will provide a baseline for identifying future changes to essential
fish habitat and so should be invaluable as a tool for managing offshore reefs. In
terms of education and outreach, Georgia Southern University actively recruits
women and underrepresented minorities and has a highly qualified pool of
minority applicants from whom to select undergraduate and graduate research
assistants. The proposed research includes the participation of at least two
undergraduate students and two graduate students. Furthermore, findings will be
presented each fall term to the biology and/or earth sciences classes at the two
public high schools in Bulloch County, GA. These high schools are comprised of
49.1% minority students. The presentations will be student-focused and
interactive, to involve students in the excitement of research and make them
aware of career opportunities in the marine sciences.
In terms of education and outreach, Georgia Southern University actively recruits
women and underrepresented minorities and has a highly qualified pool of
minority applicants from whom to select undergraduate and graduate research
assistants. The proposed research includes the participation of at least two
undergraduate students and two graduate students. Furthermore, findings will be
presented each fall term to the biology and/or earth sciences classes at the two
public high schools in Bulloch County, GA. These high schools are comprised of
49.1% minority students. The presentations will be student-focused and
interactive, to involve students in the excitement of research and make them
aware of career opportunities in the marine sciences.