Seagrass density correlates with burrow abundance and size in the Zebra Mantis Shrimp (Stomatopoda: Lysiosquillidae) / La densidad de los pastos marinos se correlaciona con la abundancia y el tamaño de las madrigueras de los camarones mantis cebra (Stomatopoda: Lysiosquillidae)

Introduction: Mantis shrimps are ecologically and economically important organisms in marine ecosystems. However, there is still a lack of information about their habitat, in particular, their burrows. Objective: To analyze how dense and sparse mantis shrimp burrows differ in abundance, size, sediment grain size, and water quality. Methods: We counted burrows in 10 x 10 m2 random plots in sparse and dense seagrass (ten plots per density), around Barrang Lompo Island, South Sulawesi, Indonesia. Sampling took place at spring low tide from August to September 2017. Results: Two mantis shrimp species were observed: Lysiosquillina maculate and L. sulcata. Dense and sparse seagrass burrows did not differ in wall grain size or water parameters, both inside and outside of the burrows (P > 0.05). Similarly, there was no correlation between burrow depth and diameter in either dense (P > 0.05; r= 0.27) or sparse (P > 0.05; r= 0.33) seagrass. However, larger burrows tend to occur in denser beds, but there were more burrows in denser seagrass (t-test, P < 0.05). Conclusions: There seems to be a preference for dense seagrass beds, especially by larger mantis shrimps. The correlation between shrimp burrow abundance and seagrass density highlights the importance of conserving the quality as well as the extent of seagrass habitat.

Introducción: Los camarones mantis son organismos ecológica y económicamente importantes en los ecosistemas marinos. Sin embargo, aún falta información sobre su hábitat, en particular sobre sus madrigueras. Objetivo: Analizar cómo difieren las madrigueras de los camarones mantis en su abundancia, tamaño, tamaño de grano de los sedimentos y calidad del agua. Métodos: Contamos las madrigueras en parcelas de 10 x 10 m2 al azar (diez parcelas por densidad) en pastos marinos densos y poco densos, alrededor de la isla de Barrang Lompo, Sulawesi del Sur, Indonesia. Resultados: Se observaron dos especies de camarones mantis: Lysiosquillina maculata y L. sulcata. El tamaño de grano de las paredes de las madrigueras y los parámetros de agua, tanto dentro y fuera de la madriguera no variaron (P > 0.05). Tampoco hubo correlación entre la profundidad y el diámetro de las madrigueras, tanto en praderas densas (P > 0.05; r= 0.27), como no densas (P > 0.05; r= 0.33). Sin embargo, las madrigueras más grandes tienden a aparecer en las praderas densas, además había más madrigueras en pastos densos (t-test, P < 0.05). Conclusiones: Parece haber una preferencia por las praderas marinas densas, especialmente en los camarones mantis de mayor tamaño. La correlación entre la abundancia de madrigueras de camarones y la densidad de pastos marinos pone de manifiesto la importancia de conservar la calidad del hábitat de los pastos, así como su extensión.

Intra- and inter-annual variation in a seagrass meadow on the Caribbean coast of Costa Rica: 2009-2015 / Variación intra e inter anual en una pradera de pastos marinos en la costa caribeña de Costa Rica: 2009-2015

Abstract Seagrass beds are an important ecosystem on the Caribbean coast of Costa Rica. At Cahuita National Park (CNP) a seagrass bed at Perezoso has been monitored continually since 1999 within the CARICOMP program. Thalassia testudinum is the dominant seagrass species, in some cases mixed with Syringodium filiforme. The results from the 2009 to 2015 monitoring period are presented here, and contrasted with data before 2009. Total (above and below ground tissue) mean biomass of T. testudinum was higher (1 255.4 ± 146.0 gm-2) than biomass before 2009, with an increasing tendency. However, productivity (1.5±0.59 gm-2d-1) and turnover rate (4.3 ± 1.22 %d-1) were lower than previous monitoring periods. In this period, mean leaf area diminished considerably (4.9 ± 2.30 m2), but leaf area index (LAI) increased (1.9 ± 0.80 m2leafm-2) in comparison to prior monitoring. Productivity, density, turnover rate, LAI and biomass showed intra-annual variations; while mean biomass of T. testudinum did not vary significantly among years. No correlations were found between water salinity, temperature and clarity with seagrass measurements. However, most seagrass parameters were strongly correlated with precipitation. These results highlight the effect of external environmental agents acting on the ecosystem. CNP presents a long-term stable seagrass meadow. However, there are indirect signals, such as high biomass and above-ground biomass proportion, along with low productivity and LAI, which point to a nutrient increment in Perezoso's seagrass bed. To continue protecting this seagrass bed, it is necessary to improve monitoring methods, and seagrass beds should be included in national conservation policies and monitoring programs. Rev. Biol. Trop. 66(3): 1149-1161. Epub 2018 September 01.

Resumen Los lechos de pastos marinos son un ecosistema importante en la costa caribeña de Costa Rica. En el Parque Nacional Cahuita (PNC), un lecho de pastos marinos en Perezoso ha sido monitoreado continuamente desde 1999 dentro del programa CARICOMP. Thalassia testudinum es la especie dominante, en algunos casos mezclada con Syringodium filiforme. Se presentan los resultados del período de monitoreo del 2009 al 2015. La biomasa promedio de T. testudinum fue mayor (1 255.4 ± 146.0 gm-2) que la biomasa antes de 2009, mostrando una tendencia creciente. Sin embargo, la productividad (1.5 ± 0.59 gm-2d-1) y la tasa de recambio (4.3 ± 1.22 %d-1) fueron inferiores a los períodos de monitoreo previos. En este período, el área foliar media disminuyó considerablemente (4.9 ± 2.30 m2), pero el Índice de Área Foliar (LAI) aumentó (1.9 ± 0.80 m2 hoja m-2) en comparación con el monitoreo previo. El promedio de la productividad, la densidad, la tasa de recambio, el LAI y la biomasa mostraron variaciones intra-anuales, mientras que la biomasa promedio de T. testudinum no varió significativamente entre los años, lo que representa un período estable. Ningún parámetro del agua de mar (salinidad, temperatura o turbiedad) se correlacionó con los parámetros del pasto marino. Sin embargo, la mayoría de los parámetros del pasto marino estaban fuertemente correlacionados con la precipitación. Estos resultados ponen en evidencia el efecto de factores ambientales externos sobre el ecosistema. El PNC tiene condiciones estables a largo plazo en las que se establece el pasto marino sin que haya evidencia de pérdida de biomasa. Sin embargo, hay señales indirectas; como el aumento de la biomasa y de la proporción de biomasa sobre el sustrato, así como una baja productividad y LAI; que apuntan a un incremento de nutrientes en el lecho de pastos marinos de Perezoso. Para continuar protegiendo este lecho marino, es necesario mejorar la calidad del agua y los métodos de monitoreo, además de incluir a estos hábitats en las políticas nacionales de conservación.

Comparative assessment of bacterial diversity associated with co-occurring eukaryotic hosts of Palk Bay origin.

Epibacterial communities of co-occurring eukaryotic hosts of Palk Bay origin (five seaweed species (Gracilaria sp, Padina sp, Enteromorpha sp, Sargassum sp, and Turbinaria sp) and one seagrass [Cymodaceae sp]) were analyzed for diversity and compared using 16S rRNA based Denaturant Gradient Gel Electrophoresis analysis. Diversity index revealed that Turbinaria sp hosts highest bacterial diversity while it was least in Gracilaria sp. The DGGE band profile showed that the epibacterial community differed considerably among the studied species. Statistical assessment using cluster analysis and Non-metric multidimensional scale analysis also authenticated the observed variability. Despite huge overlap, the composition of bacterial community structure differed significantly among the three closely related species namely Sargassum, Turbinaria and Padina. In addition, Enteromorpha and Sargassum, one being chlorophyta and the other phaeophyta showed about 80% similarity in bacterial composition. This differs from the general notion that epibacterial community composition will vary widely depending on the host phyla. The results extended the phenomenon of host specific epibacterial community irrespective of phylogeny and similarity in geographical location.

Declines of seagrasses in a tropical harbour, North Queensland, Australia, are not the result of a single event.

A recent paper inferred that all seagrass in Cairns Harbour, tropical north-eastern Australia, had undergone ‘complete and catastrophic loss’ as a result of tropical cyclone Yasi in 2011. While we agree with the concern expressed, we would like to correct the suggestion that the declines were the result of a single climatic event and that all seagrass in Cairns Harbour were lost. Recent survey data and trend analysis from an on-ground monitoring program show that seagrasses in Cairns Harbour do remain, albeit at low levels, and the decline in seagrasses occurred over several years with cyclone Yasi having little additional impact. We have conducted annual on-ground surveys of seagrass distribution and the above-ground meadow biomass in Cairns Harbour and Trinity Inlet since 2001. This has shown a declining trend in biomass since a peak in 2004 and in area since it peaked in 2007. In 2012, seagrass area and above-ground biomass were significantly below the long-term (12 year) average but seagrass was still present. Declines were associated with regional impacts on coastal seagrasses from multiple years of above-average rainfall and severe storm and cyclone activity, similar to other nearby seagrass areas, and not as a result of a single event.

Morphological and physiological responses of seagrasses (Alismatales) to grazers (Testudines: Cheloniidae) and the role of these responses as grazing patch abandonment cues / Respuestas morfológicas y fisiológicas de los pastos marinos (Alismatales) a los herbívoros (Testudines: Cheloniidae) y el papel de estas respuestas como señales de abandono de parches de pastoreo

Green sea turtles, Chelonia mydas, are grazers influencing the distribution of seagrass within shallow coastal ecosystems, yet the drivers behind C. mydas patch use within seagrass beds are largely unknown. Current theories center on food quality (nutrient content) as the plant responds to grazing disturbances; however, no study has monitored these parameters in a natural setting without grazer manipulation. To determine the morphological and physiological responses potentially influencing seagrass recovery from grazing disturbances, seagrasses were monitored for one year under three different grazing scenarios (turtle grazed, fish grazed and ungrazed) in a tropical ecosystem in Akumal Bay, Quintana Roo, Mexico. Significantly less soluble carbohydrates and increased nitrogen and phosphorus content in Thalassia testudinum were indicative of the stresses placed on seagrasses during herbivory. To determine if these physiological responses were the drivers of the heterogeneous grazing behavior by C. mydas recorded in Akumal Bay, patches were mapped and monitored over a six-month interval. The abandoned patches had the lowest standing crop rather than leaf nutrient or rhizome soluble carbohydrate content. This suggests a modified Giving Up Density (GUD) behavior: the critical threshold where cost of continued grazing does not provide minimum nutrients, therefore, new patches must be utilized, explains resource abandonment and mechanism behind C. mydas grazing. This study is the first to apply GUD theory, often applied in terrestrial literature, to explain marine herbivore grazing behavior.

Las tortugas verdes, Chelonia mydas, son herbívoros que influencian la distribución de pastos marinos en sistemas costeros someros, sin embargo los factores que hay detrás del uso de un parche de pastos marinos por C. mydas son desconocidos. Teorías actuales se centran en calidad de alimento (contenido de nutrientes en tejido) conforme la planta responde a la alteración causada por el pastoreo; sin embargo no hay estudios que hayan monitoreado estos parámetros en un diseño natural sin manipulación del herbívoro. Para deter minar las respuestas morfológicas y fisiológicas (productividad, morfología y almacenamiento de nutrientes) que potencialmente influencian la recuperación de los pastos de la alteración por pastoreo, los pastos fueron monitoreados por un año en tres escenarios diferentes de pastoreo (pastoreo por tortuga, pastoreo por peces, sin pastoreo) en el sistema tropical Bahía de Akumal, Quintana Roo, México. Significativamente menos carbohidratos solubles y mayor contenido de nitrógeno y fósforo fueron indicativos del estrés causado por el pastoreo en los pastos. Para determinar si estas respuestas fisiológicas de los pastos son las causantes del heterogéneo comportamiento de pastoreo de C. midas, reportado en Akumal, se mapearon y monitorearon parches de pastos en intervalos de seis meses. Los parches abandonados tuvieron menor biomasa, en vez de bajo contenido de nutrientes en hoja, o de carbohidratos en raíces. Estos resultados sugieren un comportamiento modificado de renunciamiento por densidad: el umbral crítico donde el costo de pastoreo continuo no provee los nutrimentos mínimos, por lo tanto nuevos parches deberán ser utilizados, explicando así el abandono del recurso y mecanismo detrás del comportamiento de pastoreo por C. mydas. Este es el primer estudio en aplicar la teoría de renuncia por densidad, frecuentemente utilizada en la literatura terrestre, para explicar el comportamiento de pastoreo de herbívoros.

Seagrasses in tropical Australia, productive and abundant for decades decimated overnight.

Seagrass ecosystems provide unique coastal habitats critical to the life cycle of many species. Seagrasses are a major store of organic carbon. While seagrasses are globally threatened and in decline, in Cairns Harbour, Queensland, on the tropical east coast of Australia, they have flourished. We assessed seagrass distribution in Cairns Harbour between 1953 and 2012 from historical aerial photographs, Google map satellite images, existing reports and our own surveys of their distribution. Seasonal seagrass physiology was assessed through gross primary production, respiration and photosynthetic characteristics of three seagrass species, Cymodocea serrulata, Thalassia hemprichii and Zostera muelleri. At the higher water temperatures of summer, respiration rates increased in all three species, as did their maximum rates of photosynthesis. All three seagrasses achieved maximum rates of photosynthesis at low tide and when they were exposed. For nearly six decades there was little change in seagrass distribution in Cairns Harbour. This was most likely because the seagrasses were able to achieve sufficient light for growth during intertidal and low tide periods. With historical data of seagrass distribution and measures of species production and respiration, could seagrass survival in a changing climate be predicted? Based on physiology, our results predicted the continued maintenance of the Cairns Harbour seagrasses, although one species was more susceptible to thermal disturbance. However, in 2011 an unforeseen episodic disturbance – Tropical Cyclone Yasi – and associated floods lead to the complete and catastrophic loss of all the seagrasses in Cairns Harbour.

Faunistic analysis of the caridean shrimps inhabiting seagrasses along the NW coast of the Gulf of Mexico and Caribbean Sea

Seagrass meadows are highly productive and ecologically important habitats in estuaries and coastal lagoons, and contain a variety of faunal communities, from which the caridean shrimps are a dominant component. The purpose of this work was to analyze the environmental parameters of water and sediments, with the biological components in seagrass epifaunal communities, from the Western Gulf of Mexico and the Caribbean Sea. For this, density and diversity of caridean shrimps were analyzed and correlated with environmental parameters and seagrass biomass, and zoogeographic affinities were determined. The spatial distribution of caridean shrimps was recorded for 12 localities with Halodule wrightii and Thalassia testudinum monospecific seagrass meadows. A total of 72 158 individuals of 16 taxa were collected. Among results, the Hippolytidae resulted the most abundant group (92.3%) with eight species, and was followed by Palaemonidae with 7.6% of the abundance and seven species, and the Alpheidae with only one genus. From the total of collected carideans, a 37.3% was found in H. wrightii and 62.7% in T. testudinum. The dominant species were Hippolyte zostericola (12.39ind./m2), Tozeuma carolinense (9.5ind./m2), Thor dobkini (4.84ind./m2) and Palaemonetes vulgaris (4.87ind./m2). The zoogeographic distribution of the carideans presented two groups: species of the Virginian-Carolinean province representing its Southern limit (43.75%) and species of the Brazilian-Caribbean province representing its Northern limit (56.25%). The species H. zostericola, T. carolinense, P. vulgaris, P. pugio and P. intermedius are widely distributed along the Western Atlantic coast. This study has base line information for seagrass habitats, the community of epifaunal carideans and their ecological affinities, previous to the oil spill in the Gulf of Mexico.

Las praderas de pastos marinos son hábitats altamente productivos y ecológicamente importantes a lo largo de las costas y estuarios, en estas se encuentra una gran variedad de comunidades faunísticas, donde los camarones carideos son un componente dominante por su densidad. Los parámetros ambientales del agua y sedimento y los componentes biológicos de biomasa de pastos marinos y comunidad epifaunística fueron recolectados a lo largo del occidente del Golfo de México y Mar Caribe. La densidady diversidad de los camarones carideos fueron analizadas y correlacionadas con los parámetros ambientales y biomasa de pastos, también se determinaron las afinidades zoogeográficas de las especies. La distribución espacial de los camarones carideos fue registrada en 12 localidades con praderas monoespecíficas de los pastos Halodule wrightii y Thalassia testudinum. Un total de 72 158 individuos pertenecientes a 16 taxa fueron recolectados. La familia Hippolytidae incluyó a ocho especies y representó el 92.3% de la abundancia, la familia Palaemonidae comprendió a siete especies y el 7.6%, y la familia Alpheidae estuvo representada por un solo género. Del total de carideos recolectados, el 37.3% se capturó en H. wrightii y el 62.7% en T. testudinum. Las especies dominantes fueron Hippolyte zostericola (12.39ind./m2), Tozeuma carolinense (9.5ind./m2), Thor dobkini (4.84ind./m2) y Palaemonetes vulgaris (4.87ind./m2). La composición zoogeográfica de los carideos estudiados estuvo representada por dos grupos: el primero constituido por especies afín a la provincia Virginiana- Carolineana en su límite más sureño (43.75%), y el segundo por especies de la provincia Brasileña-Caribeña con su límite más norteño (56.25%). Las especies H. zostericola, T. carolinense, P. vulgaris, P. pugio y P. intermedius tienen una amplia distribución a lo largo de la costa noreste Atlántica. Este estudio constituye la línea base de información sobre los hábitats de pastos marinos, la comunidad de camarones carideos epifaunales y sus afinidades ecológicas de recolectas previas al derrame de petróleo en el noreste del Golfo de México.

Dietary habits of juveniles of the Mayan cichlid, Cichlasoma urophthalmus, in mangrove ponds of an offshore islet in Belize, Central America

Foraging habitats of juveniles of the Mayan cichlid, Cichlasoma urophthalmus (Günther, 1862), were investigated in two mangrove ponds located in Twin Cays offshore islet in Belize: Sink Hole pond (SH) and Hidden Lake pond (HL). Sink Hole pond is a semiclosed body of water, whereas Hidden Lake pond is connected by a channel to adjacent seagrass beds that surround the islet. Gut contents of 21 juvenile C. urophthalmus (9.8-13.2 cm total length) were analyzed, and five prey taxa were identified. In both mangrove ponds, C. urophthalmus were opportunistic carnivores and consumed primarily crustaceans. Plant material and detritus present in gut contents were most likely ingested incidentally when the fish foraged on small invertebrates. Carbon isotopic values of fish specimens from the two ponds were similar (mean ± SD of -19.2 ± 0.4‰ in SH and -19.4 ± 0.4‰ in HL), and were close to those of mangrove prey (mean ± SD = -20.2 ± 1.5‰), suggesting that this fish species forages in this habitat. Mixing models showed a higher contribution of mangrove food sources to the fish diet than seagrass food sources. This study reveals that young Mayan cichlids, inhabiting two Belize mangrove ponds, are generalists and opportunistic carnivores that forage on mangrove food sources and do not appear to move to adjacent seagrass beds to complement their diets. Understanding trophic linkages between aquatic consumers and food resources may contribute to better management of threatened coastal ecosystems.

Habitats de alimentação de juvenis do ciclídeo-maia, Cichlasoma urophthalmus (Günther, 1862), foram investigados em duas lagoas de mangue localizadas nas ilhas Twin Cays em alto mar em Belize: Sink Hole Lake (SH) e Hidden Lake (HL). Sink Hole é um corpo d'água parcialmente isolado, enquanto Hidden Lake é ligada por um canal com bancos de sargaços que cercam a ilhota. O conteúdo estomacal de 21 juvenil de C. urophthalmus (9,8-13,2 cm de comprimento total) foram analisados e cinco táxons de presas foram identificados. Em ambas as lagoas de mangue, 'C.' urophthalmus foram carnívoros oportunistas e consumiram principalmente crustáceos. Material vegetal e detritos presentes no conteúdo digestivo foram provavelmente ingeridos acidentalmente quando o peixe se alimentava de pequenos invertebrados. Os valores de isótopos estáveis do carbono em espécimes de peixes das duas lagoas foram semelhantes (média ± SD -19,2 ± 0,4 ‰ em SH e -19,4 ± 0,4 ‰ em HL), e foram próximos aos de presas de mangue (mean ± SD = -20.2 ± 1.5 ‰), sugerindo que esta espécie de peixe vai à procura de alimentos neste habitat. Modelos mistos mostraram uma maior contribuição de fontes alimentares de mangue para a dieta dos peixes do que de fontes alimentares de algas marinhas. Este estudo revela que juvenis do ciclídeo-maia que habitam duas lagoas de mangue em Belize, são carnívoros generalistas e oportunistas que se ingerem alimentos dos manguezais e não parecem se mover para leitos de algas marinhas adjacentes para complementar suas dietas. Compreender as ligações tróficas entre consumidores aquáticos e recursos alimentares pode contribuir para uma melhor gestão dos ecossistemas costeiros ameaçados.

Biodiversidad íctica de praderas de pasto marino de la costa noroeste del Golfo de Cariaco, Venezuela / Ichthyc biodiversity of seagrass meadows from the Northwest coast of Cariaco Gulf, Venezuela

Ichthyc biodiversity of seagrass meadows from the Northwest coast of Cariaco Gulf , Venezuela. Seagrasses are highly productive coastal ecosystems with a high diversity and abundance of fishes, very important to support artisanal fisheries. We analyzed the fish community structure of Thalassia testudinum in the communities of Manzanillo (M) and La Brea (LB), Northwest coast of Cariaco Gulf, Venezuela. Samples were taken monthly (Nov. 2006-Oct. 2007) from each place, using a beach net. A total of 34 810 fishes were captured, grouped into 13 orders, 36 families and 83 species. In both areas (M and LB), the number of species was similar, but a variation in their abundance was found: a total of 55 species and 13 210 organisms for M, and 58 species and 21 600 organisms for LB. The most abundant species and those with the highest biomasses in both areas were: Nicholsina usta, Haemulon boschmae, H. steindachneri, Harengula jaguana, Halichoeres bivittatus and Hemiramphus brasiliensis. The occasional visitors were the most frequent community components with a 59%, the cyclical and permanent residents were represented by the 22% and 19%, respectively. The H’n average for M was of 1.71±0.64bits/ind., while for LB was of 1.95±0.51bits/ind. The diversity values were directly related to the evenness and inversely related to the dominance. The low values of similarity indexes among localities allow us to assert that these fish communities are dissimilar, because of the structure of each Thalassia meadow and their connectivity with other systems. Rev. Biol. Trop. 60 (2): 635-648. Epub 2012 June 01.

Los pastos marinos son ecosistemas costeros de alta productividad, con gran diversidad y abundancia de peces, la cual es aprovechada por pescadores artesanales. En este estudio se analizó la estructura comunitaria íctica de praderas de Thalassia testudinum en Manzanillo (M) y La Brea (LB), costa noroeste del Golfo de Cariaco, Venezuela. También, se realizaron muestreos mensuales (11-2006 al 10-2007), con la utilización de una red playera. Se capturaron 34 810 organismos agrupados en 13 órdenes, 36 familias y 83 especies. En ambas zonas, el número de especies fue similar, aunque el número de organismos vario, y se encontró para M un total de 55 especies y 13 210 organismos y para LB 58 especies y 21 600 organismos. Las especies más abundantes y de mayor biomasa en el área muestreada fueron: Nicholsina usta, Haemulon boschmae, H. steindachneri, Harengula jaguana, Halichoeres bivittatus y Hemiramphus brasiliensis. Los visitantes ocasionales fue el componente comunitario más frecuente con 59%, los cíclicos y los residentes permanentes obtuvieron 22 y 19%, respectivamente. En M la H’n fue de 1.71±0.64bits/ind; entretanto en LB fue 1.95±0.51bits/ind. Los valores de la diversidad estuvieron relacionados directamente con la equitabilidad e inversamente con la dominancia. Los bajos valores del índice de similaridad, entre localidades permite establecer que estas comunidades ícticas son disimiles, debido quizás a la estructuración de cada pradera de Thalassia y a la conectividad con otros sistemas.

Distribution of fish in seagrass, mangroves and coral reefs: life-stage dependent habitat use in Honduras

Many coral reef fish exhibit habitat partitioning throughout their lifetimes. Such patterns are evident in the Caribbean where research has been predominantly conducted in the Eastern region. This work addressed the paucity of data regarding Honduran reef fish distribution in three habitat types (seagrass, mangroves, and coral reefs), by surveying fish on the islands of Utila and Cayos Cochinos off the coast of Honduras (part of the Mesoamerican barrier reef). During July 2nd - Aug 27th 2007 and June 22nd - Aug 17th, 2008, visual surveys (SCUBA and snorkel) were performed in belt transects in different areas: eleven coral reef, six seagrass beds, and six mangroves sites. Juvenile densities and total habitat surface area were used to calculate nursery value of seagrass and mangroves. A total of 113 fish species from 32 families were found during underwater surveys. Multi-dimensional analyses revealed distinct clusters of fish communities in each habitat type by separating fish associated with seagrass beds, mangroves, and coral reefs. Coral reefs showed the highest mean fish species richness and were dominated by adult fish, while juvenile fish characterized seagrass beds and mangrove sites. Habitat use differed widely at the fish species level. Scarus iseri (Striped Parrotfish), the most abundant fish in this study, were found in all three habitat types, while Lutjanus apodus (Schoolmaster Snapper) juveniles were located primarily in mangroves before migrating to coral reefs. Many species used seagrass beds and mangroves as nurseries; however, the nursery value could not be generalized at the family level. Furthermore, for some fish species, nursery value varied between islands and sites. Our results suggest that connectivity of seagrass, mangrove, and coral reef sites at a species and site levels, should be taken into consideration when implementing policy and conservation practices. Rev. Biol. Trop. 60 (2): 683-698. Epub 2012 June 01.

Muchos peces de arrecifes de coral estan sometidos a la fragmentación del habitat a lo largo de su vida. Estos patrones son evidentes en el Caribe donde la investigación se llevó a cabo, principalmente en la región este. La motivación para la realización de este trabajo fue la escasez de datos sobre la distribución de peces de arrecife de Honduras en tres tipos de hábitat (pastos marinos, manglares y arrecifes de coral), por lo que se realizaron censos de peces en las islas de Utila y Cayos Cochinos en la costa de Honduras (parte del Sistema Arrecifal Mesoamericano). Del 2 de Julio al 27 de agosto 2007 y del 22 de junio al 17 agosto 2008, se realizaron censos visuales (buceo y snorkel) en transectos de diferente área: 11 en arrecifes de coral, 6 en praderas de pastos marinos y 6 en manglares. La densidad de jóvenes y el área total de la superficie del hábitat se utilizaron para calcular el valor de la zona de crianza de pastos marinos y manglares. Un total de 113 especies de peces de 32 familias fueron encontrados durante los censos. Análisis Multi-dimensionales reveló distintos grupos de comunidades de peces en cada tipo de hábitat por la separación de los peces asociados a los lechos de pastos marinos, manglares y arrecifes de coral. Los arrecifes de coral presentaron el mayor promedio de riqueza de especies de peces y fueron dominados por peces adultos, mientras que los jóvenes se caracterizaron por encontrarse en praderas de pastos marinos y zonas de manglares. El uso del hábitat difiere ampliamente a nivel de especies de peces. Scarus iseri (loro rayado), el pez más abundante en este estudio, se encontró en los tres tipos de hábitats, mientras que Lutjanus apodus, los jóvenes, se encontraron principalmente en los manglares antes de emigrar a los arrecifes de coral. Muchas especies utilizan las praderas marinas y los manglares como criaderos, sin embargo, el valor de criadero no puede ser generalizado a nivel familiar. Además, para algunas especies de peces, el valor de criadero varió entre las islas y los sitios. Nuestros resultados sugieren que la conectividad de los pastos marinos, manglares y arrecifes de coral a nivel de especies y sitios, debe ser tomado en cuenta para la aplicación de políticas y prácticas de conservación.

Biological activities of the sulfated polysaccharide from the vascular plant Halodule wrightii

A sulfated polysaccharide (SPSG) was successfully isolated from seagrass Halodule wrightii Asch., Cymodoceaceae, and its antioxidant and anticoagulant activities were investigated. The data presented here showed that the SPSG is a 11 kDa sulfated heterogalactan with a sulfatation degree of 20.63 percent and it also contains glucose and xylose. SPSG antioxidant activities were evaluated using several in vitro assays and the anticoagulant activity was evaluated by aPTT and PT tests. These assays suggested that the SPSG possessed remarkable antioxidant properties in different in vitro assays and an outstanding anticoagulant activity 2.5-fold higher than that of heparin Clexane® in the aPTT test. This data represents the first reported on the sulfated polysaccharide biological activities from seagrass. These results indicate that SPSG can be considered in the future as a drug utilized in treating diseases from these systems.

Spatial and temporal structure of fish assemblages in a hyperhaline coastal system: Ría Lagartos, Mexico

The spatial and temporal fish species assemblages were analyzed throughout two annual cycles (2004-2005 and 2007-2008) in the Ría Lagartos Lagoon system, Mexico, via non-parametric multivariate analyses. We compared density and biomass of fish species among five habitat types defined by combinations of structure and environmental characteristics (hyperhaline, rocky, seagrass, channel, and marine), and three climatic seasons (dry, rainy, and northerlies). A total of 11,187 individuals distributed in 32 families and 63 species were collected. The most numerically abundant species were Floridichthys polyommus and Cyprinodon artifrons, while Sphoeroides testudineus contributed to the greatest biomass. Species composition consisted mainly of estuarine and euryhaline marine species. Spatially, a saline gradient was observed with marine conditions in the mouth, and increasing to over 100 in the inner zone of the system. Species richness, diversity and biomass declined from the mouth to the inner zone, while density showed an inverse tendency, with the highest values in the inner zone. Thus the salinity was the variable that best explained the spatial fish assemblages" structure. The ichthyofauna composition did not change over time, but the dominant species varied with the years. The abundance of juvenile specimens, suggest that the different habitats are used as feeding and breeding zones; hence it is proposed that protection strategies be pursued not only for the lagoon system but also for the northern zone of the Yucatan Peninsula.

Los ensamblajes espacio temporales de peces fueron analizados a través de dos ciclos anuales (2004-2005) y 2007-2008) en el sistema lagunar Ría Lagartos, México, vía análisis multivariados no paramétricos. Se comparó la densidad y biomasa de peces entre los cinco tipos de hábitats definidos por la combinación de características estructurales y ambientales (hiperhalino, rocoso, pastos, canal y marino) y tres temporadas climáticas (secas, lluvias y nortes). Un total de 11.187 individuos fueron recolectados, distribuidos en 32 familias y 63 especies. Las especies numéricamente más abundantes fueron Floridichthys poliommus y Cyprinodon artifrons, mientras que Sphoeroides testudineus contribuyó principalmente con la biomasa. La composición de especies consistió principalmente de especies marinas eurihalinas y estuarinas. Espacialmente, un gradiente de salinidad fue observado con condiciones marinas en la boca del sistema lagunar, incrementándose hacia la zona interna con valores superiores a 100. La riqueza de especies, diversidad y biomasa disminuyó desde la boca hacia la zona interna, mientras que la densidad mostró una tendencia inversa, con valores más altos en la zona interna. La salinidad fue la variable que mejor explicó la estructura espacial de los ensamblajes de peces. La composición de la ictiofauna no cambió en el tiempo, pero las especies dominantes varían con los años. La abundancia de especímenes juveniles sugiere que los diferentes hábitats son usados como zonas de alimentación y de crianza; por lo que se propone que la estrategia de protección continúe no sólo para el sistema lagunar sino para toda la zona norte de la Península de Yucatán.

Monitoring coral reefs, seagrasses and mangroves in Costa Rica (CARICOMP)

The coral reefs, seagrasses and mangroves from the Costa Rican Caribbean coast have been monitored since 1999 using the CARICOMP protocol. Live coral cover at Meager Shoal reef bank (7 to 10m depth) at the Parque Nacional Cahuita (National Park), increased from 13.3% in 1999, to 28.2% in 2003, but decreased during the next 5 years to around 17.5%. Algal cover increased significantly since 2003 from 36.6% to 61.3% in 2008. The density of Diadema antillarum oscillated between 2 and 7ind/m2, while Echinometra viridis decreased significantly from 20 to 0.6ind/m2. Compared to other CARICOMP sites, live coral cover, fish diversity and density, and sea urchin density were low, and algal cover was intermediate. The seagrass site, also in the Parque Nacional Cahuita, is dominated by Thalassia testudinum and showed an intermediate productivity (2.7±1.15 g/m2/d) and biomass (822.8±391.84 g/m2) compared to other CARICOMP sites. Coral reefs and seagrasses at the Parque Nacional Cahuita continue to be impacted by high sediment loads from terrestrial origin. The mangrove forest at Gandoca, within the Refugio Nacional de Vida Silvestre Gandoca-Manzanillo (National Wildlife Refuge), surrounds a lagoon and it is dominated by the red mangrove, Rhizophora mangle. Productivity and flower production peak was in July. Biomass (14kg/m2) and density (9.0±0.58 trees/100m2) in Gandoca were relatively low compared to other CARICOMP sites, while productivity in July in Costa Rica (4g/m2/d) was intermediate, similar to most CARICOMP sites. This mangrove is expanding and has low human impact thus far. Management actions should be taken to protect and preserve these important coastal ecosystems. Rev. Biol. Trop. 58 (Suppl. 3): 1-22. Epub 2010 October 01.

Los arrecifes coralinos, pastos marinos y manglares de la costa Caribe de Costa Rica han sido monitoreados desde 1999 siguiendo el protocolo de CARICOMP. La cobertura de coral vivo en el arrecife de Meager Shoal (7 a 10m de profundidad) en el Parque Nacional Cahuita, aumentó de 13.3% en 1999, a 28.2% en 2003, pero después bajó, por los siguientes 5 años, a aproximadamente 17.5%; la cobertura de algas aumentó significativamente de 36.6% en 2003 a 61.3% en 2008. La densidad de Diadema antillarum osciló entre 2 y 7 ind/m2 mientras que Echinometra viridis decreció significativamente de 20 a 0.6 ind/m2. Comparado con otros sitios CARICOMP, la cobertura de coral vivo, diversidad y densidad de peces, y densidades de erizos de mar fueron bajas y la cobertura algal intermedia. El sitio de pastos marinos, también en el Parque Nacional Cahuita, está dominado por Thalassia testudinum y tiene una productividad (2.7±1.15g/m2/d) y biomasa (822.8±391.84g/m2) intermedia comparado a otros sitios CARICOMP. Los arrecifes coralinos y pastos marinos en el Parque Nacional Cahuita continúan siendo impactados por sedimentos terrígenos. El bosque de manglar en Laguna Gandoca, dentro del Refugio Nacional de Vida Silvestre Gandoca-Manzanillo, está bordeado por una laguna y predomina el mangle rojo, Rhizophora mangle. El pico de productividad y producción de flores fue en julio. La biomasa (14 kg/m2) y densidad (9.0±0.58 árboles/100 m2) en Gandoca fueron relativamente bajas comparadas con otros sitios CARICOMP, mientras que la productividad en julio en Costa Rica (4g/m2/d) fue intermedia, similar a la mayoría de los sitios CARICOMP. Este manglar se está expandiendo y tiene muy poco impacto humano hasta ahora. Se deben tomar acciones de manejo para proteger y preservar estos importantes ecosistemas costeros.

Environmental state and tendencies of the Puerto Morelos CARICOMP site, Mexico

The CARICOMP site at Puerto Morelos, Mexico was monitored from 1993 to 2005. No significant changes in air temperature, wind patterns, periodicity and quantity of rainfall, sea-surface temperature and water transparency were observed between sampling years. During the study four hurricane impacts were registered. At the coral reef site overall mean cover of fleshy algae (47%) and turf algae (36%) were high, whereas cover of corals (2%) and sponges (3%), and abundance of sea-urchins (0.04 org m-2) were consistently low. Gorgonians were dominant and showed changes in their community structure; the number of species increased from 1993 to 1995, their abundance decreased after Hurricane Roxanne (1995) and recovered by 2001. At four seagrass sites total community biomass remained constant (707.1-929.6 g dry m-2) but the above-ground biomass of the seagrass Syringodium filiforme and fleshy algae increased gradually. Total biomass (531-699 g dry m-2) and leaf productivity (0.89-1.56 g dry m-2 d-1) of the seagrass Thalassia testudinum remained constant, but the species invested proportionally more biomass in above-ground leaf tissues at the end of the study. The minor hurricanes from 1993 until 2005 had no detectable impacts on the seagrass beds, however, the major Hurricane Wilma (October 2005) changed the community composition at three stations and caused complete burial of the vegetation at a coastal station. The gradual changes in the seagrass and reef communities recorded in the 12 years of continuous monitoring of the CARICOMP site may reflect the increased pollution caused by the rapid augment in urban and tourist developments along the coasts and inland from Puerto Morelos, coupled with poor water management practices. Rev. Biol. Trop. 58 (Suppl. 3): 23-43. Epub 2010 October 01.

El sitio CARICOMP en Puerto Morelos, México, se monitoreo de 1993 a 2005. No se registraron cambios significativos en la temperatura del aire, los patrones de viento, la periodicidad y cantidad de lluvia, la temperatura superficial del mar y la transparencia del agua entre los años de muestreo. Durante el estudio se registraron cuatro huracanes menores. En el sitio del arrecife coralino la cobertura global promedio de algas carnosas (47%) y de algas tipo tapete (36%) fue elevada, mientras que la cobertura de corales (2%), esponjas (3%) y la abundancia de erizos (0.04 m-2) fue consistentemente baja. Los gorgonáceos fueron dominantes y mostraron cambios en su estructura comunitaria; el número de especies aumentó de 1993 a 1995, su abundancia disminuyó después del Huracán Roxanne (1995) y se recuperó en el 2001. En cuatro estaciones de pastos marinos la biomasa total de la comunidad permaneció constante (707.1-929.6 gps m-2) pero la biomasa sobre el sustrato del pasto Syringodium filiforme y de algas carnosas aumentó gradualmente. La biomasa total (531-699 gps m-2) y productividad de hojas (0.89-1.56 gps m-2 d-1) del pasto Thalassia testudinum permaneció constante, pero la especie invirtió proporcionalmente más biomasa en el tejido de hojas sobre el sustrato al final del estudio. Los huracanes menores entre 1993 y 2005 no produjeron impactos detectables en las camas de pastos, sin embargo, el huracán mayor Wilma (Octubre 2005) cambió la composición de la comunidad en tres estaciones y causó el enterramiento completo de la vegetación en la estación costera. El cambio gradual en las comunidades de pastos marinos y arrecife registrado en 12 años de monitoreo continuo en el sitio CARICOMP puede reflejar un aumento en la contaminación causada por el rápido incremento en desarrollo urbano y turístico a lo largo de la costa y tierra adentro de Puerto Morelos, acompañado por malas prácticas de manejo del agua.

Temporal patterns in coral reef, seagrass and mangrove communities from Chengue bay CARICOMP site (Colombia): 1993-2008

Few monitoring programs have simultaneously assessed the dynamics of linked marine ecosystems (coral reefs, seagrass beds and mangroves) to document their temporal and spatial variability. Based on CARICOMP protocol we evaluated permanent stations in coral reefs, seagrass beds and mangroves from 1993 to 2008 in Chengue Bay at the Tayrona Natural Park, Colombian Caribbean. Overall, the studied ecosystems showed a remarkable stability pattern over the monitoring period. While there were annual variations in coral reefs (coral cover) and mangroves (litterfall) caused by hurricane Lenny in 1999, particular trends in seagrass (leaf area index and leaf productivity) appear to reflect the natural variability in this ecosystem. We suggest that monitoring sites at the three marine ecosystems had in general a healthy development in the last 16 years. Our results are critical to locally improve the management strategies (Tayrona Natural Park) and to understand the long-term dynamics of closely associated marine ecosystems in the Caribbean. Rev. Biol. Trop. 58 (Suppl. 3): 45-62. Epub 2010 October 01.

Pocos programas de monitoreo han estudiado simultáneamente la dinámica de ecosistemas marinos estrechamente relacionados (arrecifes coralinos, pastos marinos y manglares) para documentar su variabilidad espacial y temporal. Siguiendo el protocolo de monitoreo del programa CARICOMP, estaciones permanentes de monitoreo en estos ecosistemas fueron evaluadas entre 1993 y 2008 en la Bahía de Chengue del Parque Nacional Natural Tayrona (Caribe Colombiano). En general los ecosistemas monitoreados han presentado un patrón de estabilidad durante los años de estudio. Mientras los arrecifes coralinos (cobertura de coral) y manglares tuvieron algunas variaciones anuales debidas al paso del huracán Lenny en 1999, los pastos marinos registraron tendencias particulares de cambio (índicece de área foliar y productividad de hojas) que podrían estar reflejando la variabilidad natural de la pradera estudiada.Por lo tanto se sugiere que los sitios monitoreados en cada ecosistema han tenido un desarrollo saludable en los últimos 16 años. Estos resultados son importantes para mejorar localmente las estrategias de manejo (Parque Nacional Natural Tayrona) y para evaluar la dinámica a largo plazo en los ecosistemas marinos del Caribe.

Spatial and temporal variations in phytoplankton in coral reef and seagrass ecosystems of the Palk Bay, southeast coast of India.

Spatial and temporal behavior of distribution of phytoplankton of the coral reef and seagrass environment of the Palk Bay was studied during April 2002 to March 2003. A total of 133 species of phytoplankton was recorded during the study period, of which, 98 species belong to Bacillariophyceae, 15 species belong to Dinophyceae, 12 species belong to Cyanophyceae and 8 species belong to Chlorophyceae. Diatoms (57.14 to 94.10%) contributed more towards the percentage composition of different groups of phytoplankton at the two stations, followed by dinoflagellates (3.12 to 28.57%), blue-greens (2.43 to 12.5%) and greens (3.7 to 7.69%). Higher phytoplankton population density was recorded during the summer season at both stations (St.1. 62,000 cells l-1 and St.2. 55,000 cells l-1). Coral reef environment was two-fold more productive (2.10-130.21 mg C m-3 hr-1) than the seagrass environment (3.30 - 85.56 mg C m-3 hr -1). Chlorophyll ‘a’ concentration showed higher values at station 1, corresponding to the higher phytoplankton population density recorded at this station along with primary productivity.

Community structure of the ichthyofauna associated with seagrass beds ( Halodule wrightii) in Formoso River estuary - Pernambuco, Brazil

Seagrass beds are used by juvenile fishes in different ways, generally as nursery sites, shelter from predators, reducing competition and increasing availability of food resources, thus establishing a relationship of connectivity with other ecosystems. In the present study, the community structure of the ichthyofauna associated with seagrass beds on the Formoso River (Pernambuco - Brazil) was evaluated during the winter of 2008. Twenty-seven manual trawls (15 daytime and 12 nighttime) were performed, and a total of 358 fishes belonging to 18 families, 21 genus and 25 species were collected. The Catch Per Unit Effort (CPUE) by trawling average was 13.5 and 4.95 individuals per species per trawl. The most abundant families were Scaridae (n = 111), Tetraodontidae (n = 63), Lutjanidae (n = 56), Mullidae (n = 39) and Engraulidae (n = 19). Ecological indices for dial changes were always higher for the night period, confirming that such areas are used more frequently during this period. The need for measures to conserve these areas is emphasized, by its importance and vulnerability to human impacts.

Pradarias de fanerógamas são utilizadas pela ictiofauna, de maneira geral como ambiente de berçário, abrigo contra predadores, diminuição de competição em aior disponibilidade de recursos alimentares, estabelecendo uma relação de conectividade com demais ecossistemas costeiros. No presente estudo foi avaliada a estrutura da ictiofauna associada às pradarias de fanerógamas do estuário do Rio Formoso no litoral de Pernambuco durante o inverno de 2008. Foram realizados no total 27 arrastos manuais (15 diurnos e 12 noturnos), nos quais foram amostrados 358 peixes pertencentes a 18 famílias, 21 gêneros e 25 espécies. A Captura por unidade de esforço (CPUE) média por arrasto foi de 13,5 indivíduos e 4,95 espécies por arrasto. As famílias mais abundantes foram Scaridae (n = 111), Tetraodontidae (n = 63), Lutjanidae (n = 56), Mullidae (n = 39) e Engraulidae (n = 19). Analisando os índices ecológicos, observou-se que os mesmos foram sempre maiores para o período da noite, confirmando o fato do uso de tais áreas pela ictiofauna de forma mais intensa neste período. A necessidade de medidas para proteção destas áreas é evidente na região devido a sua importância e vulnerabilidade a impactos antrópicos.

Trama trófica de una comunidad de peces en una pradera marina en el Caribe Venezolano

Trophic network of a fish community in a seagrass bed in the Venezuelan Caribbean. Seagrass beds are considered important feeding places for a variety of fish species characterized with complex trophic interactions. In this paper we described the trophic network of a fish community inhabiting a seagrass bed in the Venezuelan Caribbean. In addition, a consumption index (CI) for each prey ingested is proposed using two variables: abundance and consumption frequency. Eight samplings (at four time intervals: 6:00, 12:00, 18:00 and 24:00 hours) were done in August 2005 and January 2006. Fifty one fish species in 29 families were captured; Haemulidae was the most abundant. Crustacea was the most important food resource of the 28 food items identified. The relative importance of trophic guilds, considering abundance and taxonomic species richness, was: benthophagous>herbivorous>piscivorous. The features of the trophic network were: 1) high proportion of short chains (two links), 2) high number of intermediate species, 3) high consumption of benthos, 4) low CI values and 5) few species with a high number of linkages. Temporal (hourly and monthly) differences were obtained in fish species number (total, intermediate and top), total linkages, connectivity and maximal chain lengths. The connectance did not show significant temporal variation and it was similar to other environments with different species richness. In contrast, the connectivity was lower than the one reported for environments with low species richness. As in other reports, the temporal variation of the trophic parameters and the community structure was different. The values of CI for the different preys were low except for harpacticoid copepods and crustacean larvaes. The cluster value of CI was high for benthos (>80 %) and, in general, low for plankton and nekton preys. The seagrass bed studied was an important feeding place where the configuration of trophic network changed in different temporal scales and reflected the dynamic of the feeding relationships this fish community. Rev. Biol. Trop. 57 (4): 963-975. Epub 2009 December 01.

Las praderas marinas son consideradas sitios importantes de alimentación para una variedad de especies de peces, por lo que en estos sistemas son frecuentes las interacciones tróficas complejas. En el presente trabajo se describió la trama trófica de la ictiofauna en una pradera marina ubicada en el Caribe Venezolano. Adicionalmente, se propuso una medida de la intensidad de consumo de cada presa (IC), considerando dos variables: la abundancia y la frecuencia de uso. Se realizaron ocho muestreos (en 4 horarios: 6:00, 12:00, 18:00 y 24:00 horas) en agosto 2005 y enero 2006. Se capturaron 51 especies pertenecientes a 29 familias siendo Haemulidae la más abundante y se identificaron 28 items alimenticios dentro de los cuales, Crustácea fue el más importante como recurso alimenticio. La importancia de los gremios tróficos considerando la abundancia y la riqueza taxonómica de especies fue: bentófago>herbívoro>piscívoro. Las características de la trama trófica fueron las siguientes: 1) una mayor proporción de cadenas cortas (dos eslabones), 2) un elevado número de especies intermedias. 3) un elevado consumo de bentos, 4) unas bajas intensidades de consumo y 5) un reducido número de especies involucradas en el mayor número de uniones tróficas estimadas. Se obtuvieron diferencias temporales (horarias y mensuales) en el número de especies (totales, intermedias y topes), de uniones totales, en la conectividad y en la longitud máxima de cadena. No se observó una variación temporal en la conectancia y sus valores resultaron parecidos a los reportados para otros ambientes marinos con distinta riqueza de especies. Por el contrario, los valores de conectividad resultaron menores a los obtenidos en ambientes con menor riqueza de especies. Como en otros reportes, los parámetros tróficos estimados fueron poco sensibles a los cambios intracomunitarios. IC resultó bajo, a excepción de lo obtenido para los copépodos harpacticoides y las larvas de crustáceos, mientras que, los valores de IC agrupados resultaron altos para las presas del bentos (>80 %) y, en general, bajos para las presas del plancton y necton. La pradera evaluada fue un importante sitio de alimentación en el que cambió la configuración de la trama trófica a distintas escalas temporales, reflejando la dinámica de las relaciones alimentarias de la comunidad de peces.

Growth dynamics and state of the seagrass Thalassia testudinum in the Gandoca-Manzanillo National Wildlife Refuge, Caribbean, Costa Rica / Dinámica de crecimiento y estado del pasto marino Thalassia testudinum en el Refugio Nacional de Vida Silvestre Gandoca-Manzanillo, Caribe, Costa Rica

Seagrass beds are highly productive and valuable habitats, which fulfill a key role in coastal ecosystems. Spatial distribution, biomass, density, productivity and leaf dynamics of the dominant seagrass species Thalassia testudinum were studied at five locations in the Gandoca-Manzanillo National Wildlife Refuge, Caribbean coast of Costa Rica, from November 2005 until March 2006. Seagrass beds within the study area cover approximately 16 ha. Spatial and temporal differences in ecological seagrass parameters were examined along gradients of riverine inputs and related to a range of environmental parameters (depth, grain size distribution, nutrient concentrations, salinity and temperature). Average canopy cover and above-ground biomass of T. testudinum inversely correlated with depth, but did not vary significantly between study sites when compared along depth ranges. Considerable spatio-temporal variations in shoot densities, areal productivity and leaf sizes seem to be related to riverine inputs and wave energy. It appeared that T. testudinum at exposed sites respond to increased environmental disturbance related to the offset of the rainy season with clonal recruitment, whereby shoot densities increase and average leaf sizes are reduced. Lower shoot densities and greater leaf sizes, in contrast, are characteristic for locations with rather consistent environmental conditions, where seagrasses are sheltered. T. testudinum in the refuge has higher shoot densities but shorter leaves and lower productivity compared to sites in 15 other Caribbean countries. The seagrass beds appear to be in a relatively healthy state, however, observations of temporal increased stocks of filamentous epiphytes and macroalgae indicate temporal environmental stress in the system. Rev. Biol. Trop. 57 (Suppl. 1): 187-201. Epub 2009 November 30.

Las praderas de pastos marinos son sitios altamente productivos y hábitats valiosos en los ecosistemas costeros. Se estudió los cambios espaciales y temporales en la distribución del pasto marino dominante Thalassia testudinum, en cinco localidades expuestas a un gradiente de influencia fluvial, en el Refugio Nacional de vida Silvestre Gandoca-Manzanillo, Costa Rica, entre noviembre 2005 y marzo 2006. El pasto cubre unas 16ha. Tanto cobertura como biomasa disminuyen al aumentar la profundidad, pero no hubo diferencia de cobertura y biomasa entre lugares. Las variaciones espacio-temporales en densidad de estolones, productividad y tamaño de hojas, probablemente están relacionadas con la entrada de agua del río y la energía de las olas. Al parecer T. testudinum responde a disturbios ambientales con reclutamiento clonal: la densidad de estolones aumenta y las hojas son más pequeñas. En Gandoca-Manzanillo la densidad de estolones es mayor, las hojas más cortas y la productividad inferior, en comparación con otros 15 sitios del Caribe. Según estos parámetros, los pastos marinos de Gandoca-Manzanillo están en muy buenas condiciones. Sin embargo, se observaron aumentos en algas filamentosas epífitas y de macroalgas, que indican un impacto temporal en el sistema.

Spatial and temporal variations of meiofaunal communities from the western sector of the Gulf of Batabanó, Cuba: II. Seagrass systems

The meiofauna from seagrass meadows in the western sector of the Gulf of Batabanó, Cuba were studied to describe the spatial and temporal variations in community structure. Replicated cores were taken in three locations (arranged in m- and km-scales) and in two seasons (dry and wet). The meiofauna (metazoans between 500 and 45 microm) were identified to major taxa. Temporal changes in the meiofaunal communities could not be detected and they are not linked to the subtle seasonal changes in the water column. A larger variation in community structure was observed in the spatial m-scale (among cores in a station) probably accredited to heterogeneity of microenvironment and biological processes. A second source of variation in the km-scale (among locations) was identified relating to physical processes affecting seagrass meadows: marine currents and anthropogenic disturbances. Distribution patterns of meiofauna across locations coincide with one study from 20 years ago in seagrass beds (i.e. higher densities in area closer to break-shelf and diminution of fauna at southern of Pinar del Rio); however, cumulative anthropogenic disturbances on seagrass meadows would most likely explain the depletion of communities observed in our survey in comparison with decades ago. Estimates of meiofaunal density and richness of major taxa from our study (and other areas from the Cuban shelf) are consistently lower than other temperate and tropical sites; possibly caused by low primary productivity due to narrow tidal amplitude and oligotrophic waters.

La meiofauna asociada a pastos marinos en el sector occidental del Golfo de Batabanó, Cuba se estudió para describir las variaciones espaciales y temporales en la estructura de la comunidad. Se tomaron muestras repetidas, a escala de m- y km, en tres localidades y en dos estaciones (seca y lluvia). La meiofauna (metazoos entre 500 y 45 μm) fue identificada hasta grupos taxonómicos principales. No se detectaron cambios estacionales en la estructura de las comunidades de meiofauna ni asociación con los factores abióticos en la columna de agua. La mayor variación en la estructura de la comunidad fue observada a escala espacial de metros (entre muestras en una estación), causada probablemente por la heterogeneidad del micro-ambiente y procesos biológicos. La segunda fuente de variación aparece en escala de kilómetros (entre localidades) y está relacionada a procesos físicos que afectan los pastos marinos: corrientes marinas y disturbios antropogénicos. Los patrones de distribución de la meiofauna a través de las localidades coinciden con un estudio de hace 20 años en pastos marinos (densidades mayores en las áreas más cercanas al borde de la plataforma y menores en el Sur de Pinar del Río); sin embargo, la acumulación de los efectos del impacto antropogénico probablemente explique la disminución de la densidad en las comunidades actuales de meiofauna. Los estimados de densidad de meiofauna y de riqueza de táxones en nuestro estudio (y en otras áreas de la plataforma de Cuba) son coherentemente más bajos que en otros sitios templados y tropicales; la causa posible es la baja productividad primaria debido a la estrecha amplitud de mareas y la oligotrofia de las aguas.