juveniles and adults, ranging from 54.0 mm to 191.0 mm SL, were collected and 
observed from 1983 to 1985. The larger population inhabits an estuarine creek system 
where spawning was observed in 1984 and 1985 at salinities of 26 %o and 10 %o, 
respectively. A smaller population occurs in a strictly freshwater habitat subject to 
seasonally-fluctuating water levels. Establishment of the Mayan cichlid is indicated by 
observations of spawning activity, the wide range of specimen lengths, and its 
persistence for three years in Park waters. The potential for range expansion is 
enhanced by its exceptional tolerance of changes in salinity and water levels and its 
ability to colonize varied habitats. These data suggest that the Mayan cichlid may 
become a permanent member of Florida's ichthyofauna. The source of the introduction 
remains unknown. 
1983 - 1984 
Powell, G. V. N., J. W. Fourqurean, W. J. Kenworthy, and J. C. Zieman (1991) Bird colonies 
cause seagrass enrichment in a subtropical estuary: observational and experimental 
evidence. Est. Coastal Shelf Sci. . 32:567-79. 
Colonies/roosts of piscivorous birds in Florida Bay concentrate nutrients by feeding 
away from their colonies/roosts and returning with food for young and to defecate. 
Seagrass beds surrounding the colony islands were markedly different from those 
around similar islands that did not contain colonies. Seagrass standing crop was 
enhanced up to 200 m from bird colony islands compared with islands without colonies. 
Perches were placed in shallow water and were monitored during 1983 - 1984. The 
species of seagrass were also different at colonies, where Halodule wrightii and Ruppia 
maritima predominated in zones close to the colony islands. Around islands without 
colonies, only Thalassia testudinum was present. Experimental bird perches placed to 
stimulate concentrated bird presence produced changes in adjacent seagrass meadows 
that were similar to differences between islands with colonies and those without. Over 
5 yrs, seagrass standing crop increased around the experimental perches, and species 
dominance shifted from T. testudinum to H. wrightii. No similar changes occurred at 
control locations. These experimental results indicate that the bird concentrations are 
responsible for the observed differences in seagrass communities surrounding islands 
that contain colonies. These enriched areas are significant to the seagrass ecosystem 
because many seagrasses in Florida Bay appear to be nutrient-limited. Demersal fish 
and invertebrate density and species richness have been shown to be a function of the 
seagrass standing crop and species composition, so the changes in seagrasses 
stimulated by localized bird concentrations have the capacity to alter the entire 
community structure. 
1983 - 1985 
Zieman, J. C., and J. W. Fourqurean (1985) The distribution and abundance of benthic 
vegetation in Florida Bay, Everglades National Park. Final Rep. Contract CX5280-2-2204, 
University of Virginia. South Florida Research Center, Everglades National Park, 
Homestead, FL. 105 pp. 
[NO COPY OF PAPER AVAILABLE. ABSTRACT FROM SCHMIDT (1991).] This study was 
undertaken to delineate and describe the benthic vegetation communities in the 
submerged portions of Florida Bay. Distributional, standing crop, productivity and 
isotope data along with water characteristics and sediment properties were used to 
identify seven primary benthic vegetational communities in Florida Bay: Northeast, 
East Central, Interior, Atlantic, Gulf, Mainland, and Conchie Channel. Some of these 
communities were qualitatively compared to communities described in earlier studies. 
The importance of environmental factors (salinity, temperature, and light) on 
controlling the distribution and extent of these communities in Florida Bay was 
discussed. This report also provides complete data sets for qualitative descriptions of 
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