Powerpoint template for scientific posters Swarthmore College

1
Polychaete community structure of three
artificial reefs in Tampa Bay, Florida USA
Thomas L. Dix, David J. Karlen, and Thomas M.
AshEnvironmental Protection Commission of
Hillsborough County Tampa, Florida 33619-1309
Introduction The Environmental Protection
Commission of Hillsborough Countys Artificial
Reef program was started in 1986 to promote
habitat diversity and recreational fishing in
Tampa Bay. The program has increased hard-bottom
habitat by placing over 46,000 metric tons of
concrete substrate in a series of artificial
reefs throughout Tampa Bay, covering an
approximate area of 0.51 km2. Determining the
success of the program is, in part, dependent on
the epifaunal diversity and biomass found on the
artificial reefs. The epibenthic
community structure and seasonality on the
artificial reefs in Tampa Bay has never been
studied. One previous survey was done on the
hard bottom communities in Tampa Bay, but focused
on natural substrates (Derrenbacker Lewis,
1982). A similar study was also conducted in
Delaware Bay (Foster et al., 1994) which served
as a model for this study. The objective of
our study was to compile a comprehensive list of
epibenthic organisms on the artificial reefs in
Tampa Bay and to evaluate their community
structure. A total of 124,180 organisms,
representing 441 taxa, and 14 phyla were
identified from 60 samples. Annelids represented
27 of the total number of taxa and 15.5 of
total abundance. This presentation examines the
community structure and seasonality of
polychaetes on these artificial reefs.
Results A total of 20,778 individuals
representing over 117 polychaete species and 29
families were identified from the 60 samples.
Five families comprised 52 of the overall
species richness Syllidae 18, Spionidae 10,
Terebellidae 10, Sabellidae 8, and Cirratulidae
6 (Figure 3). Three
families comprised 85 of the overall abundance
Syllidae 39, Spionidae 35 and Cirratulidae 11
(Figure 4). Syllidae,
Spionidae, Capitellidae, and Terebellidae
comprised more than 50 of species richness at
the Howard Frankland Reef during both seasons
(Figure 5). Roughly 80 of the relative abundance
for the Howard Frankland Reef was dominated by
Spionidae and Syllidae with Spionidae
representing 46 in the spring and Syllidae 68
in the fall (Figure 5).
Syllidae, Terebellidae, Nereididae,
Capitellidae, Cirratulidae, and Polynoidae
comprised 65 of the species richness at the
Bahia Beach Reef in the spring while Syllidae,
Spionidae, Sabellidae, Nereididae, and Eunicidae
comprised 56 of the species richness in the
fall. Relative abundance at the Bahia Beach Reef
was dominated by Spionidae and Syllidae during
both seasons with Spionidae (46) dominating in
the
spring and Syllidae (63) dominating in the fall
(Figure 6). Syllidae,
Spionidae, Terebellidae, Sabellidae,
Cirratulidae, and Capitellidae, comprised 66 of
species richness at the Egmont Key Reef for
spring while Syllidae, Spionidae, Sabellidae,
Terebellidae, and Cirratulidae comprised 56 in
the fall. Eighty two percent of relative
abundance for the Egmont Key Reef was dominated
by Spionidae, Syllidae and Cirratulidae for both
seasons with Syllidae (34) dominating in the
spring and Spionidae (42) in the Fall (Figure
7). Ordination
analysis indicated that the polychaete community
structure on the Bahia Beach and Egmont Key reefs
were more similar to each other than to the
Howard Frankland reef (Figure 8). Seasonal
differences within reefs were also evident,
particularly at the Howard Frankland Reef (Figure
8). Dominant species that were common to all
reefs and both seasons were Polydora websteri,
Dipolydora socialis and Syllis gracilis.
Principal Component
Analysis on the hydrographic measurements
indicated that each reef was separated spatially
by salinity
while seasonality was driven by temperature and
dissolved oxygen (Figure 9). The
BIO-ENV procedure (Clarke Ainsworth, 1993) was
used to correlate the polychaete assemblage with
the physical parameters. The best correlation was
with a combination of salinity, dissolved oxygen,
Secchi depth, and depth (?s 0.506). Salinity
had the strongest correlation for a single factor
(?s 0.387).
Conclusions Variations in polychaete community
structure between reefs and seasons were
apparent. A maximum of six families dominated
more than 50 of the species richness at each
reef and season. Syllidae and Spionidae
comprised more than 60 of the relative
abundance at each reef and in each season.
Spionidae dominated in the spring and Syllidae in
the fall at Howard Frankland and Bahia Beach,
while the opposite trend occurred at Egmont Key.
Salinity was the major factor that separated
the reefs spatially and in structuring the
polychaete community. Temperature and dissolved
oxygen were the major components in the
seasonality at each reef.
Materials methods Three artificial reefs were
chosen from different segments of Tampa Bay
Howard Frankland Reef (Old Tampa Bay), Bahia
Beach Reef (Middle Tampa Bay) and Egmont Key Reef
(Lower Tampa Bay). These reef sites provided an
opportunity to compare reef communities from each
of the three major bay segments and to verify
anecdotal evidence that suggested differences in
community makeup among similarly constructed
reefs within the same estuarine system. Ten
sampling locations were selected at each reef and
season from random coordinates. Samples were
collected by SCUBA divers from each reef in
March-April 2004 (Spring) representing the dry
season and again in August 2004 (Fall)
representing the wet season. A total of 60
samples were collected overall (Figure
1). A metal frame (16 cm x 16
cm long) was placed at the sample location. A
stainless steel epifaunal sampler was used to
remove attached organisms and to transport the
sample to the surface (Figure 2).
Sample sites on the reef were also randomly
selected for one of three different reef levels
top, middle, and bottom and one of three surface
orientations horizontal, inverted, or vertical.
Bottom hydrographic parameters and light
measurements were also recorded at each sampling
site.
Howard Frankland Reef
Literature cited Clarke, K.R. and Ainsworth, M.
1993. A Method of Linking Multivariate Community
Structure to Environmental Variables. Marine
Ecology Progress Series, 92 205-219. Derrenbacker
, J.A. and Lewis, R.R. 1982 Live Bottom
Communities of Tampa Bay. Proceedings
Tampa Bay Area Scientific Information
Symposium. Florida Sea Grant College
Report No. 65 385-392 Foster, K.L., Steimle,
F.W., Muir, W.C., Kropp, R.K., and Conlin, B.E.
1994 Mitigation Potential of Habitat Replacement
Concrete Artificial Reef in Delaware
Bay Preliminary Results. Bulletin of Marine
Science, 55(2-3) 783-795
Acknowledgments The authors wish to acknowledge
the Florida Fish and Wildlife Conservation
Commission, Division of Marine Fisheries for
their funding and cooperation Grant Agreement
FWCC-0345. Many people help in field collection
and preparing the study Anthony Chacour, Barbara
Goetting, Sara Markham, Melissa Miller, Chrissy
Holden, Steve Grabe, Sue Estes and Glen Lockwood.
For further information Please contact
Thomas L. Dix at dixt_at_epchc.org