Cobertura algal en dos sitios del Parque Nacional de Guanahacabibes, plataforma suroccidental de Cuba

Introducción: Las comunidades de macroalgas marinas del Parque Nacional Guanahacabibes no han sido estudiadas desde el punto de vista cuantitativo, a pesar de la influencia que la vegetación submarina tiene sobre la estructura y el funcionamiento de los ecosistemas costeros, componente que hasta ahora ha sido subestimado en la región. Objetivo: Evaluar la variación temporal y espacial de los géneros de macroalgas en dos sitios de María La Gorda, sur del Parque Nacional de Guanahacabibes, y evaluar la salud del arrecife de acuerdo con la cobertura de los diferentes morfo-tipos de macroalgas predominantes. Metodología: El muestreo fue cuatrimestral entre febrero 2014 y marzo 2017 en Yemayá y Laberinto, mediante buceo autónomo a una profundidad de 10 m. La cobertura algal fue estimada siguiendo la metodología AGRRA. Se usaron ocho transectos de 20 m por sitio de muestreo de acuerdo con las condiciones del arrecife y la forma del fondo. Cada cinco metros se colocó un cuadrante de 25 x 25 cm. Se calculó el porcentaje de cobertura que aporta cada género y de los grupos morfofuncionales a la cobertura total. Resultados: Los géneros dominantes durante el periodo de estudio fueron: Dictyota, Lobophora y Halimeda. Las algas carnosas y calcáreas mostraron mayor cubrimiento en Laberinto (carnosas= 57.8 ±15.6; calcáreas = 8.3 ± 6.8) que en Yemayá, (carnosas = 47.3 ± 23.1; calcáreas = 8.5 ± 9.3). Las formas costrosas son más abundantes en Yemayá (17.1 ± 15.1) que en Laberinto (7.7 ± 10). El índice de las carnosas fue superior en Laberinto (225.7 ± 110.2). Conclusión: La disminución en los niveles de cobertura de algas costrosas y la dominancia de formas carnosas como Dictyota y Lobophora en la zona de estudio, evidencian el deterioro en ambos sitios, a pesar de las políticas de conservación de parques nacionales.

Introduction: The macroalgal communities of the Guanahacabibes National Park have been poorly studied from the quantitative point of view, despite the influence that underwater vegetation has on the structure and functioning of coastal ecosystems, a component that until now has been underestimated in the Cuba region. Objetive: To evaluate the temporal and spatial variation of the macroalgal genera in two sites of María La Gorda, south of the Guanahacabibes National Park, and evaluate the reef health according to the coverage of the different predominant macroalgal morphotypes. Methodology: Sampling took place quarterly between February 2014 and March 2017, in Laberinto and Yemayá by SCUBA diving at a depth of 10 m. The algal coverage was estimated following the AGRRA methodology. Eight 20 m transects per sampling site were used according to reef conditions and bottom shape. Every five meters a 25 x 25 cm square was placed. The coverage (%) contributed per genus and morpho-functional group to the total coverage found was calculated. Results: The dominant genera during the study period were: Dictyota, Lobophora and Halimeda. Fleshy and calcareous algae showed greater coverage in Laberinto (fleshy= 57.8 ± 15.6; calcareous = 8.3 ± 6.8) than in Yemayá (fleshy = 47.3 ± 23.1; calcareous = 8.5 ± 9.3). Crustose algae were more abundant in Yemayá (17.1 ± 15.1) than in Laberinto (7.7 ± 10). The fleshy index was higher in Laberinto (225.7 ± 110.2). Conclusion: The decrease in the levels of crustose algal cover, as well as the dominance of fleshy forms Dictyota and Lobophora in the study area, shows the deterioration in both sites, despite the conservation policies of national parks.

Fish assemblage patterns in a subtropical estuary in southern Brazil / Padrões da assembleia de peixes em uma baía subtropical do sul do Brasil

Abstract: In this study, the relationship between fish assemblage structure and environmental factors was analyzed in a bay in southern Brazil. Fish were collected every two months between February and December 2002 at six sampling sites using bottom trawl nets. Abiotic data (salinity, temperature, rainfall, and depth) and biotic data (number of individuals, biomass, and total length of individuals from each species) were obtained. In total, 56 fish species representing 27 families were collected. Assemblage structure varied with seasonality, as was evidenced by the variation in temperature and rainfall in each season. Catches showed a high abundance of demersal fishes, particularly Genidens genidens, Eucinostomus gula, and E. argenteus.

Resumo: Neste estudo, a relação entre a estrutura da assembleia de peixes e fatores ambientais foi analisada em uma baía no sul do Brasil. Os peixes foram coletados a cada dois meses entre fevereiro e dezembro de 2002 em seis locais de amostragem usando redes de arrasto de fundo. Dados abióticos (salinidade, temperatura, precipitação e profundidade) e dados bióticos (número de indivíduos, biomassa e comprimento total de indivíduos de cada espécie) foram obtidos. No total, 56 espécies de peixes representando 27 famílias foram coletadas. A estrutura da assembleia variou com a sazonalidade, conforme evidenciado pela variação da temperatura e precipitação em cada estação. As capturas mostraram grande abundância de peixes demersais, principalmente Genidens genidens, Eucinostomus gula e E. argenteus.

Spatial and temporal variation of fish assemblages in a coastal lagoon of the Biosphere Reserve La Encrucijada, Chiapas, Mexico

Composition and abundance of the ichthyofauna in estuarine and coastal lagoon systems of the South Pacific in Mexico have been scarcely studied. In particular, there is a lack of information on how environmental variables determine the spatio-temporal structure of fish assemblages in those habitats. In this study, fishes were sampled by drop net during twelve months (May 2004 -April 2005) in 22 sites distributed along the Carretas-Pereyra lagoon, located in the Biosphere Reserve La Encrucijada, Chiapas, Mexico. We recorded 11 797 individuals (40 species, in 30 genera and 21 families). Dormitator latifrons was the most dominant species in terms of the Importance Value index, IV (23.05 %), followed by Lile gracilis (10.31 %), Poecilia sphenops (8.60 %) and Poecilia butleri (7.30 %). D. latifrons also accounted for more than one half of the total biomass (50.14 %). Species richness and Shannon-Wiener’s diversity indexes showed similar temporal fluctuations, reaching their highest values during the dry season. The system evidenced temporal variations in salinity, having observed four different regimes: freshwater, oligohaline, mesohaline and polyhaline. Mean richness and diversity indexes achieved their highest values during the mesohaline period. On the other hand, mean abundances (CPUE) were highest during the freshwater period. Canonical correspondence analysis (CCA) indicated that salinity and temperature were the most important environmental parameters affecting associations of fishes in terms of their abundances. Correlation analyses revealed that among the environmental variables measured in this study, transparency showed the most significant negative correlation with fish richness and Shannon-Wiener’s diversity index. At a local scale, results suggest that spatial and temporal distribution of fish assemblages are determined by differences in the regimes of salinity and transparency, primarily driven by freshwater input from rivers. Rev. Biol. Trop. 56 (2): 557-574. Epub 2008 June 30.

Se evaluó la influencia de los factores ambientales sobre la variación espacio-temporal de los ensamblajes de peces, en el sistema lagunar Carretas-Pereyra, Chiapas, México. Entre mayo de 2004 y abril de 2005, se realizaron 12 muestreos mensuales en 22 sitios. Se recolectaron 11 797 organismos, pertenecientes a 40 especies, representando a 30 géneros y 21 familias. Dormitator latifrons fue la especie dominante en Índice de Valor de importancia, IV (23.05 %), seguida por Lile gracilis (10.31 %), Poecilia sphenops (8.60 %) y Poecilia butleri (7.30 %). D. latifrons, contribuyó con 50.14 % de la biomasa total. Los valores de riqueza y diversidad de especies (H’) mostraron variaciones temporales similares, siendo más altos en la época de secas que de lluvias. El sistema lagunar presentó variaciones importantes en los valores de salinidad con los siguientes regimenes: agua dulce, oligohalino, mesohalino y polihalino. La riqueza media de especies y la diversidad alcanzaron sus valores más altos durante el periodo mesohalino. Contrario a los valores de riqueza y diversidad, la abundancia promedio (CPUE) presentó los valores más altos durante el régimen de agua dulce.