Linear breakwater reefs of the greater Caribbean: Classification, distribution & morphology.

Geomorphic differences among Caribbean reefs have long been noted. These differences are considered to reflect the presence of reefs in different stages of development, following an incomplete recovery from rapid deglacial sea-level rise. But the possibility that these reflect real developmental differences caused by variation in wind, wave, and climate regime, has never been fully considered. Here, for the first time, we quantify the geomorphology and distribution of Greater Caribbean reefs using satellite images in Google Earth and public-domain bathymetry. To do this, we first standardise their classification based on shallow geomorphology, substrate depth, and physiographic setting, and then count and categorise the total number of reefs. These data show a total of 1023 linear breakwater reefs with a combined length of 2237 km. Of this total length, 80% are fringing reefs, 16% are barriers and 4% are faros and atolls. In terms of categories, there are 16 reef subtypes present, but only 9 are common. Their distribution, however, is not uniform. In particular, flat-subtypes form 60% of breakwater reefs in southern regions, but are less common in northern regions where crest-subtypes dominate (80%). To distinguish the geomorphology of these common reef subtypes, we collect size- and length-related morphometric data from their main reef zones. These data reveal that flat and crest subtypes also have morphometric differences: flat subtypes have well-constrained morphologies with statistically consistent unimodal morphometrics characterised by large back-reef zones, smaller and steeper reef fronts, and more sinuous and persistent crestlines. Crest subtypes, by contrast, have multimodal morphometrics suggesting less consistent morphologies (or unresolved subtypes), and are characterised by crestlines with lower sinuosity, more variable back-reef and reef-front areas, and slopes. These differences in geomorphology and distribution imply that flat- and crest-subtypes are neither successional stages of a single reef type, nor a genetically related sequence of types, but distinct reefal geoforms with different modes of development. In subsequent work we will explore what controls these differences.

Variation in species diversity of deep-water megafauna assemblages in the Caribbean across depth and ecoregions.

Diversity patterns of the deep-sea megafauna in the Caribbean Basin and the Guiana ecoregion were analyzed in order to test the hypothesis of species richness variation as a function of depth and the hypothesis of non-differences between ecoregions by analyzing spatial patterns of five taxa and a merged assemblage. Collections of five taxa (corals, sea stars, sea urchins, sea lilies and gastropods) were obtained from seven oceanographic expeditions aboard the R/V Pillsbury at 310 stations between 60 and 7500 m depth. Data were sorted according to depth zones and ecoregions and were analyzed in order to estimate species richness, changes in species composition and distinction of ß-diversity by species turnover or by nestedness. The observed patterns of diversity were consistent between taxa and their assemblage: Species richness increased from the continental shelf (60-200 m deep) to the slope (200-2000 m deep), followed by a decrease at the continental rise-abyssal zone. We detected marked changes in species composition according to depth ranges. Changes in species composition in relation to ecoregions were also detected. In general, the Caribbean Basin lacks important physical barriers, causing high deep-sea ecosystem connectivity; however, variation in composition could be related to changes in environmental conditions associated with productivity and/or continental influences.

Comparison of three quick methods to estimate crab size in the land crabs Cardisoma guanhumi Latreille, 1825 and Ucides cordatus (Crustacea: Brachyura: Gecarcinidae and Ucididae) / Comparación de tres métodos rápidos para estimar el tamaño del cangrejo en los cangrejos terrestres Cardisoma guanhumi Latreille, 1825 y Ucides cordatus (Crustacea: Brachyura: Gecarcinidae y Ucididae)

Quick, reliable and non destructive methods are necessary to estimate size structure on commercial land crabs, in order to acquire relevant information concerning the health of their populations. Cardisoma guanhumi and Ucides cordatus are two land crabs that are exploited at a high scale and also in an artisan way in the Caribbean area and in the coasts of Brazil, which populations are endangered due to uncontrolled exploitation. The purpose of this work is to provide various methods to estimate indirectly crab body size. Sampling was carried out in Carenero (C. guanhumi) and Cumaná (U. cordatus) (Venezuela). For each species, three methods were used to measure burrow diameter (Vernier, internal spring caliper and photograph), and these were correlated with real body size of the crabs. Model II linear regression analyzes, i.e. Ordinary Least Squares and Mayor Axis, were used to build and test the performance of forecasting models. Cardisoma guanhumi showed a high bivariate data dispersion using Vernier and photo measuring methods, increasing these towards larger animals. Less dispersion was achieved with the spring caliper method; this resulted in the most accurate measurements of indirectly estimated body size in C. guanhumi (r²= 0.61), whereas Vernier measurements were the least precise. On the other hand, all three methods gave reliable estimates for U. cordatus, being the Vernier method the most accurate (r²= 0.71). However, in both species, all forecasting equations overestimated the size of smaller crabs (those below the mean) but underestimated the size of larger crabs. Nevertheless, all three methods were statistically significant for each of the species, and looking at the above mentioned underand overestimations, they can serve as reliable and fast non-destructive tools to be used by resource managers and field biologists to acquire size structure information concerning these two species. Vernier and internal spring caliper ...

Para la estimación de la estructura de tamaños en cangrejos terrestres comerciales y la obtención de información relevante para su manejo, es necesario utilizar métodos rápidos, confiables y no destructivos. Cardisoma guanhumi y Ucides cordatus son dos cangrejos terrestres que son explotados comercialmente en el Caribe y en Brasil. El propósito de este trabajo es suministrar métodos indirectos para la estimación del tamaño del caparazón de los cangrejos y por consiguiente, de la estructura de tallas. Los muestreos se llevaron a cabo en Carenero (C. guanhumi) y en Cumaná (U. cordatus) (Venezuela). Se utilizaron tres métodos para estimar el diámetro de sus madrigueras: Vernier, compás y fotografía. Estos se correlacionaron con el tamaño real del cangrejo. Se aplicó el análisis de regresión Ordinary Least Squares Model II y la capacidad de predicción se probó utilizando el modelo II Mayor Axis para las regresiones. Cardisoma guanhumi mostró una fuerte dispersión de sus datos en los métodos de Vernier y fotografía. Menos dispersión se obtuvo con el método del compás y fue el más preciso (r²= 0.61). Para U. cordatus las medidas con Vernier fueron la más adecuadas (r²= 0.71). Sin embargo los tres métodos fueron confiables. Los diferentes métodos mostraron ventajas y desventajas y dependerá del que aplique los métodos, decidir cuál será el más adecuado para sus propósitos.

Patterns of spatial variation of assemblages associated with intertidal rocky shores: a global perspective.

Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses.

Inventory of ascidians (Tunicata, Ascidiacea) from the National Park La Restinga, Isla Margarita, Venezuela / Inventário de ascídias (Tunicata, Ascidiacea) do Parque Nacional La Restinga, Isla Margarita, Venezuela

Although ascidians form a conspicuous part of sessile assemblages in the Caribbean, no specialized inventories have been developed in Venezuela, except for a list of 15 species reported from Margarita Island (1984). Here we present the results of a taxonomic workshop held in the Universidad de Oriente, Boca del Rio, Margarita Island during April 20-25 of 2009, sponsored by the NaGISA-Caribbean Sea program. La Restinga National park was surveyed and we found 29 species belonging to 19 genera and 10 families. The most abundant colonial species were Clavelina oblonga, Aplidium accarense, Polyclinum constellatum, Distaplia bermudensis, Symplegma rubra, S. brakenhielmi, Botrylloides nigrum and Ecteinascidia turbinata. Among the solitary ascidians Phallusia nigra, Ascidia curvata, Microcosmus exasperatus, Styela canopus, Styela sp.1 and Styela sp. 2 were the most abundant. The ascidian diversity in this lagoon is one of the highest for similar habitats in the Caribbean and seven species are new registers for Venezuela (Ascidia curvata, Ecteinascidia styeloides, Aplidium accarense, Distaplia stylifera, Trididemnum orbiculatum, Symplegma rubra, and S. brakenhielmi). One point of concern for the conservation of la Restinga National Park is the presence of possible introduced species, and some management procedures are suggested.

Apesar das ascídias formarem uma parte conspícua das comunidades incrustantes no Caribe, nenhum inventário especializado foi realizado na Venezuela, com exceção de uma lista de 15 espécies registradas na Ilha Margarita (1984). Aqui apresentamos os resultados de um workshop de taxonomia realizado na Universidad de Oriente, Boca del Rio, Margarita Island em 20-25 de abril de 2009, como parte do programa NaGISA-Caribbean Sea program. O Parque Nacional La Restinga foi estudado e encontradas 29 espécies pertencendo a 19 gêneros e 10 famílias. As espécies coloniais mais abundantes foram Clavelina oblonga, Aplidium accarense, Polyclinum constellatum, Distaplia bermudensis, Symplegma rubra, S. brakenhielmi, Botrylloides nigrum e Ecteinascidia turbinata. Entre as espécies solitárias, Phallusia nigra, Ascidia curvata, Microcosmus exasperatus, Styela canopus, Styela sp.1 e Styela sp. 2 foram as mais abundantes. A diversidade de ascídias nesta laguna é uma das maiores neste tipo de habitat no Caribe e sete espécies representam novos registros para a Venezuela (Ascidia curvata, Ecteinascidia styeloides, Aplidium accarense, Distaplia stylifera, Trididemnum orbiculatum, Symplegma rubra, e S. brakenhielmi). Uma questão de preocupação para a conservação do Parque Nacional La Restinga é a presença de possíveis espécies exóticas, portanto algumas medidas de manejo são sugeridas.

Diversidad mitooondrial en el nor-occidente de enezuela. implicaciones para prrobables rutas migratorias prehispániass / Mitochondrial diversity in Northwest Venezuela. Implications for probable prehispanic migratory routes.

La utilidad del ADN mitocondrial (ADNmt) para determinar afinidad genética entre grupos indígenas contemporáneos e inferir sobre migraciones, ha sido demostrada; pero la imposibilidad de estudiar grupos prehispánicos extintos, limita las inferencias sobre migraciones en esa época. El mestizaje en poblaciones neoamericanas ha sido caracterizado por uniones entre hombres europeos y mujeres indígenas, permitiendo detectar en la población contemporánea haplogrupos mitocondriales amerindios que informan sobre poblaciones extintas. Para conocer los linajes femeninos en el occidente de Venezuela, se estudiaron los haplogrupos del ADNmt a partir de RFLP, en una muestra de 193 individuos con antepasados procedentes del occidente de Venezuela, 81 del Estado Lara (Barquisimeto) y 112 de tres pueblos del Estado Falcón (Macu-quita=25, Macanillas=29 y Churuguara=58). Se comparó la distribución de haplogrupos entre las poblaciones y se estimó el mestizaje por línea femenina en ellas. Se comparó la distribución de cuatro haplogrupos indígenas con otras regiones de América. Se observa que en las cuatro poblaciones predominan haplogrupos amerindios, seguidos de los africanos. Al comparar la fracción indígena con el resto de América encontramos que Macanillas, Lara y Churuguara se asemejan a grupos de Amazonas y Suramérica, mientras que Macuquita a Aruba. Esto sugiere una diversidad genética importante en esa zona como probable ruta de paso hacia el sur y el Caribe; además refleja vínculos genéticos importantes entre grupos prehispánicos de Aruba y los de la Península de Paraguaná. Evidencias arqueológicas soportan estos postulados. Se recomienda aumentar la muestra y realizar análisis de secuencias para un nivel mayor de precisión.

Mitocondrial DNA (mtDNA) has been widely used to study genetic relationships between contemporary Amerindian groups and to infer ancestral migration movements; however inferences about migration routes of prehispanic extinct groups are difficult. Admixture of Neoamerican groups has been characterized by unions between European males and Amerindian females. This allows the identification in present populations of Amerindian mitocondrial haplogroups which give information on ancestral groups. In order to investigate female lineages present in western Venezuela, RFLP haplogroups from mtDNA were obtained from 193 individuals with grandparents from this region, 81 from the State of Lara (Barquisimeto) and 112 from 3 towns of the State of Falcon (Macuquita=25; Macanilla=29 and Churuguara=58). Comparison of haplogroup distributions between groups was performed, and admixture estimates based on female lineages were obtained. The distribution of four Amerindian haplogroups was compared with those of other populations from the American Continent. In our four samples Amerindian haplogroups predominate, followed by those of African origin. In the comparison of the mtDNA Amerindian fraction with other populations we find that Macanillas, Lara and Churuguara are similar to South American and Amazonian groups whilst Macuquita is similar to groups from Aruba. Our findings suggest an important genetic diversity in this region, explained by migration routes to and from the south and the Caribean. They also suggest genetic relationship between prehispanic groups from Aruba and those from the Paraguaná peninsula, which have been inferred by archeological evidences. An increase in sample size and analysis of sequences for more precision is recommended.