In 1988 data on coral reef community composition were collected from two areas, Akumal and Chemuyil, Quintana Roo, Mexico, ranging from 5-35m depth. These areas were revisited in 2005 and data were collected by the same methods and at the same depths as in 1988. Data from 1988 and 2005 were compared to determine if the coral reefs had undergone significant changes, and what specific changes had occurred. Chi-square analysis determined that community composition data collected in 1988 are significantly different from data collected in 2005 at all sites and depths within the categories of corals, gorgonians, sponges, and macroalgae. Mann-Whitney U analyses were performed on abundance data for coral, gorgonians, sponges, macroalgae, crustose coralline algae, erect coralline algae/calcareous algae, filamentous/multi-species turf algae, and non-living substrate. Results from the Mann-Whitney U analysis varied between sites; however significant trends of increasing macroalgae, crustose coralline algae and filamentous/multi-species turf, and declining non-living substrate were observed at almost all sites. H' biodiversity indices J' evenness values and species number (S) were calculated for all sites over the two time periods, with no discernable trends observed. Increases in crustose coralline algae and filamentous/multi-species turf algae suggest that eutrophication and overfishing may be responsible for the trends observed on the reefs at Akumal and Chemuyil. Anecdotal accounts also suggest that eutrophication from septic water flowing through the highly porous karst limestone of the Yucatan Peninsula may be the largest malefactor causing the observed changes. The increase in filamentous/multi-species turf algae exhibited by the data suggests that eutrophication is predominantly responsible for the alternate states of the reefs. Furthermore, evidences indicative of other forms of stress on the reefs, such as bleaching, scraped or broken coral heads, disease, and sedimentation, were rarely observed.

Submitted by Caroline Falcao (caroline.rfalcao@ufpe.br) on 2017-05-25T17:38:36Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Figueiredo, L. Dissertação.pdf: 2326085 bytes, checksum: f701ac448a676622b5e8d0f8bd978613 (MD5) / Made available in DSpace on 2017-05-25T17:38:36Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Figueiredo, L. Dissertação.pdf: 2326085 bytes, checksum: f701ac448a676622b5e8d0f8bd978613 (MD5) Previous issue date: 2014-02-07 / Este estudo teve como objetivo analisar a dinâmica da comunidade e da produção secundária dos Copepoda do microzooplâncton dos recifes costeiros de Tamandaré, PE, para entender as variações sazonais e nictemerais, e relativas as fases lunares e os principais processos que influenciam essa comunidade. Amostras foram coletadas através de arrastos horizontais com rede de plâncton (65μm de abertura de malha) durante o período chuvoso (Julho-Agosto 2010) e seco (Novembro-Dezembro 2010), nos horários diurno e noturno e durante cada fase lunar. Cinqüenta e oito taxa foram identificados. Copepoda com 23 espécies dominou e compôs aproximadamente 50% da comunidade durante o período seco. As espécies mais abundantes foram Euterpina acutifrons, Parvocalanus crassirostris e Oithona hebes. Os maiores valores de densidade foram registrados durante o período seco (10711.19 ± 7131.47 ind.*m-3 ). Embora que foram observadas maiores diferenças quantitativas entre os horários de coleta e as fases lunares, diferenças qualitativas foram observadas. A produção foi considerada baixa e refletiu os padrões da densidade, estando mais elevada no período seco (P. crassirostris 101,62 ± 159,03 μg C m-3 dia-1 ; E. acutifrons 75,75 ± 82,77 μg C m-3 dia-1 ; Oithona hebes 24,77 ± 19,43 μg C m-3 dia-1 ). Não foi observada diferença nos valores de produção entre as fases lunares. Entre os horários, as diferenças estiveram restritas apenas a E. acutifrons. De forma geral pôde-se observar a forte influência sazonal sobre a composição da comunidade do microzooplâncton e produção dos Copepoda do sistema recifal de Tamandaré, no qual a grande ocorrência de espécies estuarinas e costeiras ressalta a interação entre o sistema recifal e os estuários próximos. / This study aimed to analyze the dynamics of the microzooplankton community of the coastal reefs of Tamandaré, PE, to understand the seasonal and diel variations in relation to lunar phases and the main processes influencing the community. Samples were collected by horizontal hauls with a plankton net (65μm mesh size) in the rainy (July-August 2010) and dry (November-December 2010) seasons, during daytime and at night, and during every lunar phase. Fifty-eight taxa were identified. Copepoda, with 23 species, dominated and comprised nearly 50% of the community during the dry season. The most abundant species were Euterpina acutifrons and Parvocalanus crassirostris. Higher densities were registered during the dry season (10711.19 ± 7131.47 ind.*m-3 ). Although major quantitative differences were not observed between collection times and lunar phases, qualitative differences were observed. The secondary production was considered low, and followed the density pattern, being higher during the dry season (P. crassirostris 101,62 ± 159,03 μg C m-3 dia-1 ; E. acutifrons 75,75 ± 82,77 μg C m-3 dia-1 ; Oithona hebes 24,77 ± 19,43 μg C m-3 dia-1 ). Differences between the lunar phases were absent, and differences between the daytime and nighttime were restricted to E. acutifrons. The overall results showed the strong seasonality influence over the copepods community, both in terms of composition and production. The dominance of estuarine and coastal species indicates the connection between the reef system and adjacent estuaries.

Bahia de la Ascension (BA) is a pristine, shallow, karst bay located in the Mexican Caribbean, a region experiencing rapid population growth stimulated by intense tourism development. The overall objective of this study was to address the natural hydrographic variability of this inherently vulnerable ecosystem and assess its influence on a key habitat, the seagrass. The chapters follow the three-branched nature of the study which tackled the connected ecosystem issues of coastal hydrology, physical dynamics of flow and circulation, and the ecological dynamics of the seagrass species Thalassia testudinum in BA. Freshwater input to BA is primarily by submerged groundwater discharges and surface runoff; both sources are derived from fissures in the aquifer but feature distinct water quality due to the interaction with adjacent wetlands. Hurricanes explain 36 percent of the interannual precipitation variability in the region. The water balance indicates a persistent net outflow from BA to the adjacent shelf, suggesting an intense exchange across inlets. Both diurnal and semidiurnal tidal frequencies are attenuated in the inner bay, where a meteorologically-induced subtidal water level increase may occur during four-day southeasterly winds. A clear SW-NE salinity gradient was established during dry and rainy seasons, with a strong tidally-driven marine influence throughout the central basin, and a perennial mesohaline ambient in the southwestern-most bay, where hydrodynamics are primarily controlled by wind stress. Thalassia testudinum is the dominant seagrass species in BA, occupying ~90 percent of the substrate, including the freshwater-influenced inner bay. High nutrient inputs, including phosphorus which might have limiting effects in karst environments, along with the wind-driven circulation controlling water residence times are associated with the successful development of T. testudinum (up to 1,461.23 g DW m-2) within the SW bay. Farthest into the central basin, Thalassia consistently exhibited an inverse correlation between abundance and density of shoots. This pattern was enhanced under exceptional precipitation and inputs of denuded organic matter resulting from hurricanes making landfall on this region. The relationship between nutrient distribution and the above/belowground ratio suggested that Thalassia growing in BA favors the development of the aerial component as nutrients availability increases. This study provides a basic understanding of the most important processes molding the patterns of variability exhibited by T. testudinum in Bahia de la Ascension. The salinity gradient and external nutrient supply, along with the hydrodynamic component, define the spatial scale at which the connectivity between the adjacent wetland, the bay, and the shelf may occur.

The Veracruz Reef System (VRS) is located in the southwestern Gulf of Mexico. It is comprised of 28 coral reefs in various stages of development and conservation. They are protected under the Parque Nacional Sistema Arrecifal Veracruzano National Park created in 1992. There are many threats to the reefs of the VRS, including the Port and city of Veracruz, which hosts half a million inhabitants and Mexico’s oldest active port. The inhabitants of Veracruz have used reef resources for thousands of years, as evidenced in archaeological sites on Sacrificios island, and constructions throughout the city, most notably in the San Juan de Ulúa Fort which was built entirely of coral skeletons. Despite the usage and protection given under the National Park, there is relatively little known about the health and condition of the stony corals in the System. There has only been one large scale study of 21 reefs conducted in the VRS in the late 1980’s. Since then, the National Park was created and 28 reefs are now recognized. This study performed point-intercept transects on 24 of these reefs including five reefs added to the official list in 2012. Point-intercept transects were surveyed at 63 sites between 2007 and 2014. Percent cover was calculated for seven functional groups. Additionally, demographic data of a subset of individual stony coral colonies were assessed on each transect. The functional group with the greatest cover in the VRS was crustose coralline algae (mean ± S.E.: 28.9% ± 1.97), stony corals had the second highest cover (21.5% ± 1.24). The Jamapa river divides the VRS into two groups the Veracruz group to the North and the Anton Lizardo group to the south of the river mouth. The Veracruz group had lower crustose coralline algae cover (28.1% ± 2.71) and coral cover (17.8% ± 1.55) than the Anton Lizardo group (29.6% ± 2.87 CCA and 25.3% ± 1.86 coral cover). The highest average coral cover on a reef was recorded at Ahogado Chico (45.5% ± 5.58), and the highest cover recorded on a single transect was 70% at Santiaguillo reef. The lowest coral cover was recorded at the fringing reefs on the north of the VRS, Punta Gorda and Punta Brava which had less than 1% coral cover. Coral colonies averaged 69.1 cm ± 3.10 in length at the VRS, 56.8 cm ± 2.98 in the Veracruz group and 81.7 cm ± 5.11 in the Antón Lizardo group. Old partial mortality was 25% ± 1.05 overall and similar between groups, recent partial mortality was 1.2% ± 0.21 and 1% at both groups. Disease prevalence was 3.9% for the VRS, 2.9% ± 0.88 in the Veracruz group and 4.9% ± 1.11 in the Antón Lizardo group. Overall, these reefs are faring slightly better than other reefs in the Caribbean having higher coral cover and larger colonies. However, the great variability in the health and condition of these reefs demands added attention and clear management goals to ensure their persistence in the face of ever growing threats. It is important to decrease the sources of stress, such as construction and poor waste water management in the area, better regulate fishing and approach a watershed wide management plan which takes into account upstream effects from the rivers that discharge into the Veracruz Reef System.