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Compared to other groups of invertebrates, sponge (Porifera) taxonomy has been poorly developed in the Eastern Tropical Pacific (ETP) in general and in the Colombian Pacific in particular. This work aims to increase knowledge of the group's biodiversity in the rocky reefs of northern Chocó. Sponge samples were collected by autonomous diving, which were then processed and identified in the laboratory by standard methods. It was confirmed the low species richness and the predominance of encrusting morphologies and cryptic habits, which have been found in other studies in the region. Twenty-four (24) morphotypes belonging to 13 orders, 17 families and 21 genera were identified. Twelve (12) morphotypes were recognized at the genus level or with a tentative specific identity and the other 12 were confirmed at the species level. Six (6) species are morphologically similar to those of the Caribbean, indicating that populations may not have diverged sufficiently since the closure of the Isthmus of Panama or, alternatively, may have recently crossed the Panama Canal. RESUMEN En comparación con otros grupos de invertebrados, la taxonomía de esponjas (Porífera) ha sido poco desarrollada en el Pacífico Oriental Tropical (POT), en general, y en el Pacífico colombiano, en particular. Este trabajo busca incrementar el conocimiento de la biodiversidad del grupo en los arrecifes rocosos del norte del Chocó. Se recolectaron muestras de esponjas mediante buceo autónomo, las cuales fueron procesadas e identificadas en laboratorio por métodos estándar. Se confirmó la baja riqueza de especies y la predominancia de morfologías incrustantes y hábitos crípticos, que ha sido encontrada en otros estudios en la región. Se identificaron 24 morfotipos pertenecientes a 13 órdenes, 17 familias y 21 géneros. Doce (12) morfotipos se reconocieron a nivel de género o con identidad específica tentativa y los otros 12 fueron confirmados a nivel de especie. Seis (6) especies son morfológicamente similares a las del Caribe, lo que indica que las poblaciones posiblemente no han divergido lo suficiente desde el cierre del istmo de Panamá o, alternativamente, pueden haber cruzado recientemente el canal de Panamá.

The abundance of the invasive lionfish Pterois volitans was assessed through visual censuses conducted in 2015 and 2016 at 54 sites in six localities with coral reefs across the Colombian Caribbean coast. The invader was observed across locations and in most of the dives, with sighting frequency of 88 %, abundance values from 0 to 9.7 ± 2.1 ind/250 m2 (388 ind/ha), and 0.8 ± 1.3 ind/250 m2 (32 ind/ha) as total mean. The average density was similar to values reported in other works that counted lionfish in a broad spatial scale on the invaded area and the highest value approximated the maximum density estimated in Colombia and other locations around the Caribbean. RESUMEN Se evaluó la abundancia del pez león invasor Pterois volitans mediante censos visuales realizados en 2015 y 2016 en 54 sitios de seis localidades con arrecifes de coral a lo largo de la costa Caribe colombiana. El invasor se observó en todos los lugares y en la mayoría de las inmersiones, con una frecuencia de avistamiento de 88 %, valores de abundancia desde 0 hasta 9,7 ± 2,1 ind/250 m2 (388 ind/ha) y un promedio de 0,8 ± 1,3 ind/250 m2 (32 ind/ha). La densidad media fue similar a los valores reportados en otros trabajos que contaron pez león en una amplia escala espacial en el área invadida y el valor más alto se aproximó a la densidad máxima estimada en Colombia y otros lugares del Caribe.

El tiburón cazón antillano, Rhizoprionodon porosus, constituye un recurso importante para pesquerías artesanales de pequeña escala; es uno de los tiburones costeros más abundantes dentro de su ámbito de distribución y desempeña una importante función como depredador en los ecosistemas marino-costeros. Por sus hábitos costeros, la especie es susceptible de sufrir extracción intensiva, especialmente en estados juveniles. Para darle un manejo apropiado y conservar las poblaciones explotadas de R. porosus se necesita conocer la diversidad genética y la estructura de las poblaciones dentro de sus rangos de distribución. En este estudio se probó la habilidad de cebadores heterólogos desarrollados para otras especies de tiburones de la familia Carcharhinidae para amplificar marcadores nucleares microsatélites en R. porosus (amplificación cruzada). La variación de la frecuencia alélica de genotipos de cuatro loci microsatélites sirvió para evaluar la estructura genética de R. porosus en siete localidades de cuatro departamentos del Caribe colombiano. El análisis de varianza molecular Amova y análisis de estructura poblacional mediante el estadístico Фst para las frecuencias genotípicas, indican que hay diferenciación genética baja pero significativa entre R. porosus provenientes de los departamentos analizados (Фst (3,165)= 0.002; p = 0.000). Además, el análisis pareado indica que existe una diferenciación genética significativa entre el cazón antillano de La Guajira y las demás muestras analizadas (todos los p = 0.000). La información obtenida ayuda a entender la dinámica de las poblaciones naturales del cazón antillano, sirve de línea base para la formulación y desarrollo de estrategias de conservación y manejo de este recurso pesquero; sin embargo, dado el bajo número de loci heterólogos útiles para estudios genético poblacionales, se deben enfocar los esfuerzos de investigación en el desarrollo de marcadores específicos para futuros estudios de genética poblacional de esta especie. The Caribbean sharpnose shark, Rhizoprionodon porosus is an important resource for artisanal small-scale fisheries. It is one of the most abundant coastal sharks within its distribution range, and plays an important role as a predator in coastal marine ecosystems. For its coastal habits, it is susceptible to intensive extraction, especially the juveniles. To accomplish proper management and conservation of exploited Rhizoprionodon populations, knowledge about its genetic diversity and its population structure within their distribution range is needed. The ability of heterologous primers developed for other requiem sharks to amplify microsatellite molecular markers in R. porosus was tested in this study (cross amplification). The change in allele frequency of four microsatellite loci served to assess the genetic structure of R. porosus in the Colombian Caribbean. Analysis of molecular variance Amova and population structure analysis using the Фst statistical of genotype frequencies indicate low but significant genetic differentiation among R. porosus from the departments analyzed (Фst (3,165) = 0.002; p = 0.000). Besides, the analysis of pairs of departments indicates that there is significant genetic differentiation among La Guajira and the other samples analyzed of the Antillean sharpnose shark (all p values = 0.000). The information obtained helps to understand the dynamics of natural populations of the Caribbean sharpnose shark, serving as a baseline for the formulation, development of conservation strategies and management of this fishery resource; however, due the low number of heterologous loci useful for population genetics studies, research efforts on the development of specific markers for the species should be done for further population genetic studies of this species.

A brief description of seven benthic environments found in La Guajira's shallow continental shelf from Boca de Camarones to Cabo de la Vela between 3 to 20 m depth is presented. Cover percentage of main benthic components, organic matter proportion in sediment, and main organisms observed in each environment are listed. The dominant environment was "arenal" (sandy bottom) covering 47% of total area sampled, whereas most species were observed in the environments "fondo mixto" (mixed bottom), "cascajo compuesto" (composed gravel) and "corales y esponjas sobre cascajo" (corals and sponges on gravel).

In the continental Colombian Caribbean the conch resource exploitation and the status of snails populations has been poorly studied, which are reflected in the lack of fisheries management. This study assesses composition, population density and distribution of the gastropods species that make conch resource in La Guajira region. Underwater visual censuses for snails were performed between September-November 2009 in 145100x4m (400m2) transects, spanning a total area of 56920m2 between Riohacha and Cabo de la Vela. The study was complemented with the evaluation of composition, abundance and size of gastropods conch found in the discarded-by-fishermen shell mounds in 13 beaches. In October 2010 another 40 transects were evaluated (16 000 m2) from the Southern of Riohacha to the Camarones village (La Guajira). We found a total of 9911 snails belonging to 12 species, the most abundant being Strombus pugilis with 8 912 individuals and an average density of 1 538.4 +/- 3 662.6 ind./ha, followed by Vasum muricatum with 374 individuals and an average density of 51.8 +/- 91.2 ind./ha. Calculating the importance value index (IVI) for both living organisms as the empty shells on beaches, shows that Turbinella angulata is the most used species by artisanal fishermen in the region. Cassis madagascariensis and Cassis tuberosa are also important snail resources in the region (as suggested by the number of empty shells found in beaches), but its densities were low. Strombus gigas, with only three living organisms found in the area, presented the lowest abundance ever found in the Colombian Caribbean (0.52 +/- 3.6 ind./ha), showing that queen conch population in La Guajira cannot support commercial exploitation. The abundance of discarded S. gigas shells on beaches suggests resource exploitation in the recent past. Results remarks the urgency of implementing management plans for snail fisheries in the region.