Brachiopods, sipunculans, enteropneusts and metals from two estuarine tidal flats, Pacific, Costa Rica.

Reports on the abundances and on metal concentrations in intertidal estuarine invertebrates from the Eastern Tropical Pacific are rare. Thus, the objectives of this report are to make accessible data on the abundances (1984-1987, 49 dates; 2013, 12 dates) of sipunculans, brachiopods and hemichordates from a sand-mud flat; and on trace metals (1996, 2000) and abundances (2015, 3 dates) of sipunculans and brachiopods at a sand flat in the Gulf of Nicoya estuary (10o N-85o W). Cores (17.7 cm2) were collected at the sand-mud flat, and quadrats (0.2 m2) at the sand flat. The flats contrasted in their sand (65 % vs 90 %) and silt+clay (31.5 % vs 5.6 %) contents. At the sand-mud flat (1984-87: 1.83 m2) the sipunculans were represented by 13 individuals, the brachiopods by 129 and the acorn worms by 185, with estimated maximum densities of: 5.7, 29, and 40 ind./m2, respectively. Trace metal (Fe, Mn, Ni, Cr, Cd, Zn, and Pb) analysis (Atomic Absorption Spectrometry) were conducted in specimens of Sipunculus nudus (Sipuncula) and Glottidia audebarti (Brachiopoda). Maximum mean concentrations in S. nudus were: For non-depurated worms, Fe (16.0 mg/g dw) > Mn (165 µg/g dw) > Zn (81 µg/g dw) > Cu (26 µg/g dw) > Cr (11 µg/g dw) > Ni (10.4 µg/g dw) > Pb (9.3 µg/g dw) > Cd (1.2 µg/g dw). For 72 hour depurated worms: Fe (5.0 mg/g dw) > Mn (61 µg/g dw) > Zn (39 µg/g dw) > Cu (24 µg/g dw) > Ni (8.4 µg/g dw) > Pb (2.7 µg/g dw) > Cd (0.62 µg/g dw). For G. audebarti: Fe (1.6 mg/g dw-soft parts) > Zn (123.5 µg/g dw-soft parts) > Cu (31.4 µg/g dw-pedicles) > Pb (21.0 µg/g dw-shells) > Cd (5.2 µg/g dw-soft parts) > Cr (4.7 µg/g dw-shells). For sediments; Fe (46 mg/g dw) > Mn (41.3 µg/g dw) > Zn (63 µg/g dw) > Cu (36.2 µg/g dw) > Cr (31.5 µg/g dw) > Pb (21.1 µg/g dw) > Ni (16.1 µg/g dw) > Cd (1.1 µg/g dw). These concentrations were expected for a nonindustrialized estuary. At the sand flat (Area sampled: 10.6 m2 ) 76 individuals of G. audebarti, 112 of G. albida, and 366 of S. nudus were collected in 2015, with estimated maximum densities of: 7.1, 10.5, and 31 ind./m2, respectively. Densities of G. audebarti and G. albida were relatively low, while those of S. nudus were relatively high when compared with other reports. The shell lenght of G. audebarti ranged from 9.0 mm to 38.0 mm and from 6.0 mm to 29.0 mm for G. albida. These ranges were within those found for these lingulides elsewhere. The mean length of S. nudus was 41 mm and the maximum weight was 1.6 g, which are small. No brachiopods were found at the sand-mud flat in 2013, nor enteropneusts at the sand flat in 2015. G. audebarti had a relatively stable presence, while G. albida almost vanished from the samples at the end of 2015. The spatial distributions of the three invertebrates were found aggregated at both intertidal flats. Strong ENSO warming events during 1983 and 2015, and red tides in 1985 may have influenced the abundances.

A new genus and species of Leptocheliidae (Crustacea: Peracarida: Tanaidacea) from Isla del Coco (Costa Rica).

Samples from the scarcely-studied sedimentary seabed from the Isla del Coco (Costa Rica) yielded a single species of Tanaidacea, belonging to a new genus of Leptocheliidae, Cocotanais. The new genus shows affinities with Pseudonototanais and Heterotanais in bearing a conspicuous forcipate cheliped in the males, which in Cocotanais has a modified merus and carpal flange. Other distinct characters of the males are a triangular cephalothorax, a three-articled antennular peduncle and swollen bases of pereopods 4-6. Females have a four-articled antennule, a maxilliped endite with three distal flat spines and two inner coupling hooks, and a maxilliped basis with two long setae. The species was found in sheltered bays, both free-living in the sediment and also as a commensal of anemones (Infraorder Boloceroidaria), thus representing the first reported case of such an association. 

Crustaceans from a tropical estuarine sand-mud flat, Pacific, Costa Rica, (1984-1988) revisited.

The availability of data sets for time periods of more than a year is scarce for tropical environments. Advances in hardware and software speed-up the re-analysis of old data sets and facilitates the description of population oscillations. Using recent taxonomic literature and software we have updated and re-analized the information on crustacean diversity and population fluctuations from a set of cores collected at a mud-sand flat in the mid upper Gulf of Nicoya estuary, Pacific coast of Costa Rica (1984-1988). A total of 112 morphological species of macroinvertebrates was found, of which 29 were crustaceans. Taxonomic problems, maily with the peracarids, prevented the identification of a group of species. The abundance patterns of the crab Pinnixa valerii, the ostracod Cyprideis pacifica, and the cumacean Coricuma nicoyensis were analized with the Generalized Additive Models of the free software R. The models evidenced a variety of population oscillations during the sampling period. These oscillations probably included perturbations induced by external factors, like the strong red tide events of 1985. In additon, early on 1984 the populations might have been at an altered state due to the inpact of El Niño 1982-83. Thus, the oscillations observed during the study period departed from the expected seasonality (dry vs rainy) pattern and are thus considered atypical for this tropical estuarine tidal-flat. Crustacean diversity and population peaks were within the range of examples found in worldwide literature. However, abundances of the cumacean C. nicoyensis, an endemic species, are the highest reported for a tropical estuary. Comparative data from tropical tidal flat crustaceans continues to be scarce. Crustaceans (total vs groups) had population changes in response to the deployment of predator exclusion cages during the dry and rainy seasons of 1985. Temporal and spatial patchiness characterized the abundances of P. valeri, C. pacifica and C. nicoyenis.

Marine litter on sandy beaches with different human uses and waste management along the Gulf of Nicoya, Costa Rica.

This study was a baseline with quantitative data of marine litter along the Gulf of Nicoya, Costa Rica. The objective of the study was to quantify marine litter and its association with human activities in this estuarine gulf. A total of fourteen sandy beaches were cataloged by the degree of urbanization, tourism intensity, beach cleaning programs, and tributary rivers as possible drivers of marine litter presence. The items of the marine litter were separated and weighted by type. Analysis by the clean coastal index (CCI) and multivariate statistics were applied to find spatial patterns in marine litter in the gulf. On beaches with the highest touristic activity, cigarette butts and straws were the main components. Locations with river plume influence, less frequent cleanup, or waste cans showed more bottles, plastic parts, and sanitary waste than beaches in other conditions. A beach in a fisherman town had recently utilized plastic bags, household goods, and boat parts in the marine litter. A wildlife refuge beach showed only small plastic and coffee foam cup fragments that came with currents from other points in the estuary. River basin management, solid waste disposal programs, and environmental education to avoid single-use items combined with correct waste disposal are needed to reduce marine litter in tropical countries focused on ecological tourism.

Molluscan assemblage from a tropical intertidal estuarine sand-mud flat, Gulf of Nicoya, Pacific, Costa Rica (1984-1987).

The availability of data sets covering more than a year is scarce for tropical environments. Advances in hardware and software speed-up the re-analysis of old data sets and facilitates the identification of hidden data patterns. From February 1984 to April 1987 (49 sampling dates), core samples (17.7cm2, 15cm deep) were collected at low tide at a sand-mud flat in the mid upper Gulf of Nicoya estuary, Pacific, Costa Rica. Predator exclusion experiments (cages 0.5 x 0.5 x 0.2m, galvanized wire, mesh size 5mm), were conducted at the site in 1985 (dry and rainy seasons sets). Samples were preserved with 5% buffered formalin in sea water stained with Rose Bengal, and washed after 24 hours on a 500 micron mesh sieve. The 1 120 cores yielded a total of 112 morphological species of which the mollusks were represented by 23 species, and included the bivalves Tellina rubescens, Tagelus bourgeoisae, Dosinia dunkeri and Leukoma asperrima, and the gastropods, Natica unifasciata, Nassarius luteostomus, Costoanachis rugosa and Turbonilla sp. The 23 species are indicative of a relatively rich sedimentary molluscan fauna. T. bourgeoisae had a seasonal oscillation, with higher abundances during the rainy seasons. T. rubescens was not seasonal, but presented an oscillation with peaks at about 1.5 year intervals. Many empty shells of Cosmioconcha modesta, lower number of N. luteostomus and a few of T. rubescens were found with boreholes by the predatory snail N. unifasciata. T. rubescens was not significantly more abundant inside or outside cages. T. bourgeoisae showed a significant increase within the caged areas. The numerical fluctuations of the mollusks became more important during the rainy season of 1985. Red tide outbreaks in the Gulf of Nicoya in 1985 may have had an impact on the molluscan populations.

First record of the parasitic barnacle Anelasma squalicola Darwin, 1852 (Pollicipedomorpha: Pollicipedidae) in the Eastern Pacific Ocean and a new host report: Etmopterus benchleyi Vsquez, Ebert amp; Long, 2015 (Squaliformes: Etmopteridae).

Anelasma squalicola is a parasitic barnacle of members of the deep-water shark families Etmopteridae, Pentanchidae and Scyliorhinidae. We report the first published confirmation of this species in the Eastern Pacific Ocean, based on material collected off Costa Rica, its first record as a parasite of the Ninja lantern shark, Etmopterus benchley (Etmopteridae), and a new size record for the host. The information presented herein expands the knowledge (distribution and host usage) of this enigmatic species.

[Temporal comparison of the composition and zonation of rocky intertidal organisms at Cocos Island National Park, Pacific, Costa Rica]. / Comparación temporal de la composición y zonación de organismos en el intermareal rocoso del Parque Nacional Isla del Coco, Pacifico de Costa Rica.

Several biological and physical factors change the rocky shore communities. The desiccation time and the tolerance of the intertidal species produce the vertical zonation. In many studies around the world, a temporal change in this zonation is presented.In Costa Rica, only studies that include temporal trends were carried out in Punta Mala and Montezuma, Pacific coast in 80's. The rocky intertidal of the Cocos Island National Park, Costa Rica were surveyed photographically. The Chatham bay was sampled in three expeditions (January 2007, October 2007 and April 2008). Photos corresponding to 25x25cm quadrats were taken with the goal to determine diversity and composition differences in rocky shore organisms between sampling dates. The Wafer bay was sampled in January and October 2007. The intertidal of Chatham consists of basaltic rock, while Wafer has basaltic and ignimbrite boulders. The main difference between sites were the higher algae cover (erect-frondose forms) and number of organism bands at Chatham bay. Temporal change was not found in the total cover of sessile fauna and autotrophs. The barnacle Tetraclita stalactifera, that occurs above the algal fringe (lower intertidal), was the invertebrate with the highest coverage. The mobile fauna biodiversity presented no significant trend between sampled months. However, the identity of species, their cover and their abundance showed a moderate temporal change. In October 2007, when the sea surface temperature was 23 degrees C the infralittoral zone had an increase in green algae cover. The red algae (crust and erect-frondose forms) were dominant in January and April. The pulmonate limpet, Siphonaria gigas and a bacterial biofilm at mid littoral showed a negative association. The snails of the high littoral and the supralittoral zone showed a temporal change in their abundance, but with contrasting patterns between sites. The temporal variation in the assemblages increased from the supralittoral to the infralittoral possibly due to changes in the water temperature and climatic conditions, that could influence the intertidal zone during the high and low tide, respectively.

Mapping benthic faunal communities in the shallow and deep sediments of Las Perlas Archipelago, Pacific Panama.

Las Perlas Archipelago (LPA) is located off the Pacific Coast of Panama and was designated as a marine protected area (MPA) in 2007. This baseline study of the shallow and deeper sedimentary habitats of the islands partly informed the MPA designation. Ninety-two grab stations and twenty trawl stations were sampled. Sediment grab sample results were interpolated to produce a map that showed the area to be dominated by mud (1246 km2, 40%) and sand/shell sediments (780 km2, 25%). A total of 201 taxa were recorded and over 5800 individual specimens were processed, revealing that the sediments hold varying community compositions, with annelids being the dominant group (73%) followed by crustaceans (14%). Relationships were evident between community, feeding guilds, and sediment types, which give an indication of communities that can be expected in similar sediments in other areas of the Tropical Eastern Pacific. A study of this scale and level of detail is rare for this biogeographic region and provides a valuable, comprehensive appreciation of the LPA's benthos.

Phylogeny and latitudinal biogeography of the Papillomaviridae family / Filogenia y biogeografía latitudinal de la familia Papillomaviridae

Introduction: The latitudinal diversity gradient (LDG), a fundamental ecology pattern for higher organisms, has explained the increase of species diversity from the poles towards the tropics. Can we explain the biodiversity of Papillomaviruses based on this pattern? Objective: To analyse the phylogenetic diversity and phylogeography of most known genotypes and species belonging to Papillomaviridae Family isolated and molecularly characterized by distant latitudinal locations around the world. Methods: We collected 238 gene sequences encoding for the L1 and L2 viral capsid proteins from PaVE database. A geographical heat map based on the PV locations allowed to analyse the distribution and the number of PV species per country. Subsequently, a phylogenetic tree based on concatenated amino acid sequences L1 and L2 was constructed using a combination of Bayesian and Maximum Likelihood (ML) methods with Geneious version 11.2.1 and BEAST version 1.8.4. Statistical analysis with Principal Coordinate Analyses (PCA) using the Jaccard similarity index for presence-absence were carried out to test the similarity of the groups in the phylogenetic tree based on their viral species, the host and origin country lists. Distance-based redundancy analysis generated an ordination plot of the similarity of viral species list per group of the phylogenetic tree vs. host species per group, the country list per group and the number of samples per group. Finally, the significance of each model was tested by Analysis of variance (ANOVA). Results: A clear tendency of most of the papillomavirus (PV) species clustering in the Northern regions appeared. Our phylogenetic analyses largely support the taxonomic division into major papillomavirus genera (Alpha, Beta, Gamma, Delta, Lambda, Xi, Upsilon and Chi papillomaviruses), as reported in previous studies. Chelonid PV's, a papillomavirus in turtles, appeared as the oldest group for all papillomaviruses. Minor inconsistencies were found within some of the major taxonomic groups explained by the exhausted phylogenetic analyses. Due to the different sampling data efforts with little replication in certain groups, hosts and countries, numerical models did not fit to the proposed hypothesis. Conclusions: Phylogeographical analysis allowed determining the global distribution of papillomaviruses species diversity per latitudinal location. As most of the papillomavirus (PV) species were clustered in the Northern regions, this may clearly represent a statistical bias because larger efforts in PV studies have historically been done in the US and Europe. The biogeographical trend of a latitudinal diversity gradient does not apply for papillomaviruses. Even though no support to the phylogeographical pattern of LDG for PV was obtained, our results may only be the product of a socio-economical-scientific artefact and not a natural phenomenon.

Introducción: El gradiente de diversidad latitudinal, un patrón ecológico fundamental para los organismos superiores ha servido para explicar el incremento de la diversidad de especies desde los polos hacia los trópicos. ¿Podemos entonces explicar la biodiversidad de papilomavirus (PV) basado en este patrón? Objetivo: Analizar la diversidad filogenética y la filogeografía de los genotipos y especies más conocidas que pertenecen a la Familia Papillomaviridae aislados y molecularmente caracterizados por sus locaciones latitudinales distantes alrededor del mundo. Métodos: Recolectamos 238 secuencias de genes que codifican las proteínas de la cápside viral L1 y L2 a partir de la base de datos PaVE. Un mapa de calor geográfico basado en la ubicación de PV permitió analizar la distribución y el número de especies de PV por país. Posteriormente, un árbol filogenético basado en secuencias de aminoácidos concatenadas L1 y L2 se construyó utilizando una combinación de métodos Bayesianos y de Máxima Verosimilitud con Geneious versión 11.2.1 y BEAST versión 1.8.4. Con respecto al análisis estadístico, se realizaron tres análisis de componentes principales utilizando el índice de similitud de Jaccard para presencia-ausencia, a fin de evaluar la similitud de los grupos en el árbol filogenético en función de sus especies virales, el huésped o las listas de países. El análisis de redundancia basado en la distancia generó una gráfica de ordenación de la similitud de la lista de especies virales por grupo del árbol filogenético vs las especies hospedadoras por grupo, la lista de países por grupo y el número de muestras por grupo. Finalmente, la significancia de cada modelo se evaluó mediante análisis de varianza (ANOVA). Resultados: Existió una tendencia clara de la mayoría de las especies de papilomavirus agrupadas en regiones del norte. Nuestro análisis sustenta en gran medida la división taxonómica en los principales géneros de virus del papiloma (Alfa, Beta, Gama, Delta, Lamda, Xi, Ípsilon y Ji), como se informó en estudios anteriores. Los PV de los quelonios, papilomavirus en tortugas, apareció como el grupo más antiguo para todos los papilomavirus. Inconsistencias menores fueron encontrados dentro de algunos de los principales grupos taxonómicos explicadas por los análisis filogenéticos. Además, una serie de análisis estadísticos fueron realizados para determinar la significancia en la diversidad de especies correlacionada con la locación geográfica. Debido a diferentes esfuerzos en el muestreo de datos con poca replicación en ciertos grupos, hospedadores, y países, los modelos no se ajustaron a la hipótesis propuesta. Conclusiones: Los análisis filogeográficos permitieron determinar la distribución global de la diversidad de especies de PV por locación latitudinal. Como en la mayoría de las especies de PV fueron agrupados en las regiones del norte, esto claramente podría representar un sesgo estadístico porque esfuerzos más grandes en los estudios de PV históricamente han sido realizados en Estados Unidos de América y Europa. La tendencia biogeográfica del gradiente latitudinal de especies no aplica para los virus del papiloma. A pesar de que no se obtuvo apoyo para el patrón filogeográfico de LDG para PV, nuestros resultados podrían ser solo el producto de un artefacto social, económico y científico y no un fenómeno natural.

Crustáceos (Decapoda y Stomatopoda) del R.V. Skimmer y R.V. Victor Hensen en el Golfo de Nicoya, Pacífico, Costa Rica / Crustaceans (Decapoda and Stomatopoda) from the R.V. Skimmer and R.V. Victor Hensen in the Gulf of Nicoya, Pacific, Costa Rica

Resumen El acceso a datos actualizados, sobre los nombres y distribución de las especies de crustáceos presentes en un área en particular, es un primer paso para evaluar cambios debidos a factores locales, regionales o globales, como la sobrepesca, la contaminación y el cambio climático. Los datos en este estudio están basados en las expediciones de los buques de investigación Skimmer (20 estaciones, 1979-1980) y Victor Hensen (1993-1994, 12 estaciones) en el estuario del Golfo de Nicoya. Los crustáceos fueron recolectados mediante redes de arrastre tipo Otter (Skimmer, malla 3.5 cm) y por tipos Otter y Beam (V. Hensen, mallas de 2.5 cm y 1.9 cm) a profundidades entre 10 y 228 m. Datos en dos estudios posteriores aportaron información para una zona de entre-mareas en la región superior del Golfo y para estaciones en la boca del estuario, lo que incrementa el ámbito de profundidad de 0 a 350 m. Se revisaron las publicaciones originales y se hicieron 32 actualizaciones de los nombres de las especies con base en la literatura reciente y en la página de red World Register of Marine Species (WORMS). El total de especies para ambas expediciones fue de 131, del que 119 fueron decápodos y 12 fueron estomatópodos. Los datos en los otros dos estudios, así como la revisión de las colecciones en el Museo de Zoología de la Universidad de Costa Rica, incrementó en 43 el número de registros, para un total de 174 especies en los sedimentos del estuario. Para el Skimmer el número mínimo de especies en una estación fue de cuatro (tres estaciones) y el máximo de 27, con un promedio de 12.3 especies / estación. Para el V. Hensen el mínimo de especies en una estación fue de ocho, con un máximo de 27 y un promedio de 17 especies / estación. Las especies presentes en 50 % o más de las 20 estaciones de la expedición del Skimmer, fueron: Callinectes arcuatus, Rimapenaeus faoe, Penaeus brevirostris, Achelous asper y Hepatus kossmanni. Para la expedición del V. Hensen las especies presentes en más del 50 % de las 12 estaciones, fueron: A. asper, Sicyonia disdorsalis, S. picta y Persephona subovata. Durante el estudio del Skimmer, un total de 15 especies fueron encontradas en solo una estación, mientras que para el V. Hensen el número fue de 26. Se digitalizaron dos matrices de datos de presencia-ausencia de las especies en las estaciones y con base en los nombres actualizados de las especies recolectadas por el Skimmer (57 especies x 20 estaciones) y V. Hensen (82 especies x 12 estaciones) se les aplicó un Análisis No Métrico Dimensional de Escala (NMDS) para obtener una distribución de las estaciones en un espacio bi-dimensional. Los resultados revelaron unos grupos heterogéneos de estaciones. Algunos sub-grupos de tres o cuatro estaciones concuerdan con su proximidad geográfica. Las cuatro estaciones del V. Hensen en la boca del estuario a profundidades mayores a los 60 m fueron separadas más claramente de las otras, y podrían indicar una transición, desde aguas estuarinas hacia aguas profundas, en la composición de la fauna de crustáceos. Evaluaciones futuras de la diversidad de crustáceos del Golfo de Nicoya deben de considerar la amplia distribución espacial de algunas especies y la restringida de otras. La variabilidad temporal es también importante en el estuario, tal como lo evidenció la oscilación de la población de Pinnixulala valerii en un periodo de tres años.(AU)

Abstract The access to updated data on the names of the crustacean species and their distribution in a given area is a first step to evaluate changes due to local, regional and global factors such as overfishing, pollution, and climatic change. Data in this study are based on the expeditions of the RV Skimmer (20 stations, 1979-1980) and RV Victor Hensen (1993-1994, 12 stations) in the Gulf of Nicoya estuary. The crustaceans were collected by means of an Otter trawl (Skimmer, mesh 3.5 cm) and by Otter and Beam trawls (V. Hensen, mesh 2.5 cm and 1.0 cm, respectively) at depths from 10 m to 228 m. Data from two later studies were also included, one from an intertidal flat in the upper Gulf and the other from stations at the mouth of the estuary, which expand the depth range from 0 to 350 m. The list of species in the original publications were updated and 32 corrections were made based on recent literature and the web page, World Register of Marine Species (WORMS). The total number of species for both surveys was 131, of which 119 were decapods and 12 were stomatopods. Data from the other two studies and from the crustacean collection deposited at the University of Costa Rica Zoology Museum added 43 records for a total of 174 species collected in sediments from the estuary. For the Skimmer, the minimum number of species found in one station was four (three stations) and the maximum was 27, with an average of 12.3 species / station. For the V. Hensen, the minimum of species found in one station was eight, with a maximm of 27 and an average of 17 species / station. The species present in 50 % or more of the 20 stations of the Skimmer expedition, were: Callinectes arcuatus, Rimapenaeus faoe, Penaeus brevirostris, Achelous asper and Hepatus kossmanni. For the V. Hensen expedition, the species present in 50 % or more of the 12 stations, were: A. asper, Sicyonia disdorsalis, S. picta, and Persephona subovata. During the Skimmer survey a total of 15 species were found at only one station, while for the V. Hensen the number was 26. Two presence-absence matrices based on the updated names of the crustaceans collected by the Skimmer (57 species x 20 stations) and V. Hensen (82 species x 12 stations) were analyzed by Non Metric Dimensional Scaling (NMDS) to display the distribution of stations in a two-dimensional space. The results revealed heterogeneous groups of stations. Several sub-groups of two or three stations agreed with their geographical proximity. The four V. Hensen stations, located at the mouth of the estuary at depths greater than 60 m, were separated more clearly from the others and may indicate a transition, from estuarine to deep waters, in the composition of the crustacean fauna. Future evaluations of the crustacean diversity of the Gulf of Nicoya must take into account the wide spatial distribution of some species and the patchy distribution of others. Temporal variability is also important in the estuary as evidenced by the population oscilallations of Pinnixulala valerii over a three year period.(AU)

Influencia de la vigilancia en una zona rocosa dentro de un área marina protegida, Pacífico Central de Costa Rica / Surveillance influence in a rocky shore within a marine protected area, Central Pacific of Costa Rica

Resumen Los intermareales rocosos son sitios importantes para peces, aves, invertebrados y algas entre otros, que se utilizan para la extracción de recursos alimenticios para las comunidades costeras. Se presentan los resultados de la evaluación de una costa rocosa en el Pacífico Central de Costa Rica (Refugio Nacional de Vida Silvestre Playa Hermosa-Punta Mala), usando indicadores biológicos propuestos por el protocolo del Ministerio de Ambiente y Energía. Se analizó la influencia de la vigilancia en dos sitios dentro de un AMP sobre el intermareal rocoso. La recolección de datos se realizó durante la época seca y la época lluviosa de 2015. Los datos mostraron que Nerita scabricosta presentó muchas colonias formadas por pocos individuos. La cobertura de macroalgas y los invertebrados bajo las rocas mostraron una leve diferencia entre los niveles de vigilancia. La densidad de Tetraclita stalactifera no mostró variaciones. Se sugiere la hipótesis que el daño mecánico asociado al turismo, pesca y extracción, está influyendo sobre los organismos de la zona rocosa. Algunos de los bioindicadores utilizados mostraron ser influenciados por los niveles de vigilancia y aplicación de las medidas de manejo.

Abstract Rocky intertidal are important sites for fish, birds, invertebrates and algae, among others, which are used for the extraction of food resources for coastal communities. We present the results of conservation assessment of a rocky shore in the Central Pacific of Costa Rica (Playa Hermosa-Punta Mala National Wildlife Refuge) using the biological indicators proposed by the National Environmental Ministry. This study aims to analyze the influence of surveillance, between two sites, over the rocky shore habitat. The sampling was carried out during both the dry and rainy seasons in 2015. Our data shows that Nerita scabricosta -harvested in small-scale fisheries- presents a high number of colonies formed by few individuals. Moreover, the abundance varied between seasons, probably due to a storm surge. Macroalgae differed slightly among sites, where turf had higher percentage coverage in low surveillance areas, while brown algae had higher coverage in high surveillance areas. Mechanical damage (abrasion due to rocks overturning) associated with tourism and harvesting could be influencing the low surveillance area, explaining these differences. Macroalgae presented a seasonal change, probably related to the storm surge. The density of the Tetraclita stalactifera did not exhibit variations. The surveillance level and enforcement influenced some bioindicators of the rocky shore, and therefore could be used to assess the extractive pressure. Rev. Biol. Trop. 66(3): 984-995. Epub 2018 September 01.

Brachiopods, sipunculans, enteropneusts and metals from two estuarine tidal flats, Pacific, Costa Rica / Braquiópodos, sipuncúlidos, enteropneustos y metales en dos planicies estuarinas de marea, Pacífico, Costa Rica

Abstract:Reports on the abundances and on metal concentrations in intertidal estuarine invertebrates from the Eastern Tropical Pacific are rare. Thus, the objectives of this report are to make accessible data on the abundances (1984-1987, 49 dates; 2013, 12 dates) of sipunculans, brachiopods and hemichordates from a sand-mud flat; and on trace metals (1996, 2000) and abundances (2015, 3 dates) of sipunculans and brachiopods at a sand flat in the Gulf of Nicoya estuary (10o N-85o W). Cores (17.7 cm2) were collected at the sand-mud flat, and quadrats (0.2 m2) at the sand flat. The flats contrasted in their sand (65 % vs 90 %) and silt+clay (31.5 % vs 5.6 %) contents. At the sand-mud flat (1984-87: 1.83 m2) the sipunculans were represented by 13 individuals, the brachiopods by 129 and the acorn worms by 185, with estimated maximum densities of: 5.7, 29, and 40 ind./m2, respectively. Trace metal (Fe, Mn, Ni, Cr, Cd, Zn, and Pb) analysis (Atomic Absorption Spectrometry) were conducted in specimens of Sipunculus nudus (Sipuncula) and Glottidia audebarti (Brachiopoda). Maximum mean concentrations in S. nudus were: For non-depurated worms, Fe (16.0 mg/g dw) > Mn (165 µg/g dw) > Zn (81 µg/g dw) > Cu (26 µg/g dw) > Cr (11 µg/g dw) > Ni (10.4 µg/g dw) > Pb (9.3 µg/g dw) > Cd (1.2 µg/g dw). For 72 hour depurated worms: Fe (5.0 mg/g dw) > Mn (61 µg/g dw) > Zn (39 µg/g dw) > Cu (24 µg/g dw) > Ni (8.4 µg/g dw) > Pb (2.7 µg/g dw) > Cd (0.62 µg/g dw). For G. audebarti: Fe (1.6 mg/g dw-soft parts) > Zn (123.5 µg/g dw-soft parts) > Cu (31.4 µg/g dw-pedicles) > Pb (21.0 µg/g dw-shells) > Cd (5.2 µg/g dw-soft parts) > Cr (4.7 µg/g dw-shells). For sediments; Fe (46 mg/g dw) > Mn (41.3 µg/g dw) > Zn (63 µg/g dw) > Cu (36.2 µg/g dw) > Cr (31.5 µg/g dw) > Pb (21.1 µg/g dw) > Ni (16.1 µg/g dw) > Cd (1.1 µg/g dw). These concentrations were expected for a nonindustrialized estuary. At the sand flat (Area sampled: 10.6 m2 ) 76 individuals of G. audebarti, 112 of G. albida, and 366 of S. nudus were collected in 2015, with estimated maximum densities of: 7.1, 10.5, and 31 ind./m2, respectively. Densities of G. audebarti and G. albida were relatively low, while those of S. nudus were relatively high when compared with other reports. The shell lenght of G. audebarti ranged from 9.0 mm to 38.0 mm and from 6.0 mm to 29.0 mm for G. albida. These ranges were within those found for these lingulides elsewhere. The mean length of S. nudus was 41 mm and the maximum weight was 1.6 g, which are small. No brachiopods were found at the sand-mud flat in 2013, nor enteropneusts at the sand flat in 2015. G. audebarti had a relatively stable presence, while G. albida almost vanished from the samples at the end of 2015. The spatial distributions of the three invertebrates were found aggregated at both intertidal flats. Strong ENSO warming events during 1983 and 2015, and red tides in 1985 may have influenced the abundances. Rev. Biol. Trop. 64 (3): 1311-1331. Epub 2016 September 01.

ResumenSon raros los reportes sobre las abundancias y concentraciones de metales en invertebrados estuarinos de la zona de entre-mareas del Pacífico Este Tropical. Los objetivos de este informe son el hacer accesibles datos sobre las abundancias (1984-1987, 49 fechas; 2013, 12 fechas) de sipuncúlidos, braquiópodos y hemicordados en una planicie arenoso-fangosa y sobre metales traza (1996, 2000) y abundancias (2015, 3 fechas) de sipuncúlidos y braquiópodos en una planicie arenosa en el estuario del Golfo de Nicoya (10o N-85o W). Barrenos (17.7 cm2) fueron recolectados en la planicie arenoso-fangosa y cuadrantes (0.2 m2) en la arenosa. Las planicies contrastaron en sus contenidos de arena (65 % vs 90 %) y de limo + arcilla (31.5 % vs 5.6 %). En la planicie arenoso-fangosa (1984-87: 1.83 m2) los sipuncúlidos estuvieron representados por 13 individuos, los braquiópodos por 129 y los hemicordados enteropneustos por 185, con densidades estimadas de: 5.7, 29, y 40 ind. /m2, respectivamente. Análisis de metales traza (Fe, Mn, Ni, Cr, Cd, Zn, y Pb) por Espectrometría de Absorción Atómica (AAS) fueron hechos en especímenes de Sipunculus nudus (Sipuncula) y Glottidia audebarti (Brachiopoda). Concentraciones máximas promedio en S. nudus fueron: para gusanos no-depurados, Fe (16.0 mg/g dw) > Mn (165 µg/g dw) > Zn (81 µg/g dw) > Cu (26 µg/g dw) > Cr (11 µg/g dw) > Ni (10.4 µg/g dw) > Pb (9.3 µg/g dw) > Cd (1.2 µg/g dw). Para gusanos depurados por 72 horas: Fe (5.0 mg/g dw) > Mn (61 µg/g dw) > Zn (39 µg/g dw) > Cu (24 µg/g dw) > Ni (8.4 µg/g dw) > Pb (2.7 µg/g dw) > Cd (0.62 µg/g dw). Para G. audebarti: Fe (1.6 mg/g dw-partes suaves) > Zn (123.5 µg/g dw-partes suaves) > Cu (31.4 µg/g dwpedículos) > Pb (21.0 µg/g dw-conchas) > Cd (5.2 µg/g dw-partes suaves) > Cr (4.7 µg/g dw-conchas). Para sedimentos; Fe (46 mg/g dw) > Mn (41.3 µg/g dw) > Zn (63 µg/g dw) > Cu (36.2 µg/g dw) > Cr (31.5 µg/g dw) > Pb (21.1 µg/g dw) > Ni (16.1 µg/g dw) > Cd (1.1 µg/g dw). Estas concentraciones fueron esperables para un estuario no industrializado. En la planicie arenosa (Area muestreada: 10.6 m2) 76 individuos de G. audebarti, 112 de G. albida y 366 de S. nudus fueron recolectados en el 2015, con densidades estimadas de: 7.1, 10.5, y 31 ind. /m2, respectivamente. Densidades de G. audebarti y G. albida fueron relativamente bajas, mientras que las de S. nudus fueron relativamente altas cuando se les comparó con otros reportes. La longitud de la concha de G. audebarti varió entre 9.0 mm y 38.0 mm y entre 6.0 mm a 29.0 mm la de G. albida. Estos ámbitos estuvieron dentro de los encontrados para estos lingúlidos en otros sitios. La longitud promedio de S. nudus fue 41 mm y el peso máximo fue de 1.6 g que son pequeños. En la planicie arenoso-fangosa no se encontró braquiópodos en el 2013, ni enteropneustos en la planicie arenosa en el 2015. G. audebarti tuvo una presencia relativamente estable, mientras que G. albida casi desapareció de las muestras al final del 2015. La distribución espacial de las tres especies fue de tipo agregado en ambas planicies. Fuertes eventos ENSO durante 1983 y 2015, así como mareas rojas en 1985, pueden haber influenciado las abundancias.

Macrofauna bentónica de las playas de arena del Área de Conservación Osa, Puntarenas, Pacífico Sur de Costa Rica / Benthic macrofauna found in Sandy beaches from Osa Conservation Area, Puntarenas, Southern Pacific coast of Costa Rica

Resumen Se describe la diversidad y composición de especies las playas de arena del Pacífico Sur de Costa Rica. En las playas de arena de la región, se colectó individuos de la infauna por medio de barrenos. Para la zona de entre mareas arenosa el número de especies estrictamente marina varió de 5 a 13 taxones, número que es intermedio con los reportados previamente para estos ambientes en Costa Rica. En la zonas de arena, el supralitoral lo dominó el isópodo Cirolana salvadorensis, mientras nereidos y un gusano de la Familia Pisionidae dominaron en el infralitoral. Otros organismos encontrados en las playas fueron cangrejos del género Uca, cangrejos anomuros (Emerita), galletas de mar (Mellita longifissa) y varios grupos de poliquetos tubícolas permanentes o temporales de la familias Onuphidae, Spionidae, Magelonidae y Glyceridae. Las playas mostraron variación en su fauna atribuible en ciertos casos a la exposición al oleaje, teniendo menos fauna en las playas más reflectivas. Se mencionan acitivades humanas que pueden explicar la baja riqueza de especies encontrada en algunas de las playas analizadas.

Abstract The diversity and species composition of the intertidal sandy beaches in the southern Pacific coast of Costa Rica were studied by means of cores collected along perpendicular transects to the beaches. The numbers of strictly marine species varied between 5 to 13 taxa, representing an intermediate value compared to those previously reported for these environments in Costa Rica. The isopod Cirolana salvadorensis was the dominant species in the supralittoral zone, whereas polychaete worms belonging to the families Nereididae and Pisionidae dominated the low intertidal zone. Others organisms collected in the beaches were the crabs of the genus Uca, anomurans crabs (Emerita), sand dollars (Mellita longifissa) and several taxa of polychaete tubeworms, such as the Onuphidae, Spionidae, Magelonidae, and Glyceridae. The high faunal difference among the sites is possibly explained by their exposure to the wave energy, with fewer individuals in the more reflective beaches. In addition, human activities might also be responsible for the low infaunal diversity found in some of these beaches. This is the first effort to describe the benthonic fauna of beaches from this area. Rev. Biol. Trop. 63 (Suppl. 1): 273-285. Epub 2015 April 01.

Polychaetes associated with decaying wood in Térraba mangrove, South Pacific, Costa Rica / Poliquetos asociados a madera en descomposición en el manglar de Térraba, Pacífico Sur, Costa Rica

Abstract The present study shows spatial patterns in the faunal assemblage of decaying wood and sediments, with emphasis on the polychaetes. The survey was executed across a salinity gradient in a tropical mangrove estuary of Costa Rica. To capture the organisms we analyzed decomposing logs found in the Térraba mangrove and sediment samples were taken with a corer in the sand bottom. Seven different phyla were found in the sediment samples. Of the 192 individuals found in the sediment samples, 18 were polychaetes belonging to nine families and 11 species. Analyses of decaying wood resulted in 2 564 individuals distributed in five phyla. Polychaetes accounted for 429 individuals belonging to eight families and 16 species. Although, polychaetes were more abundant in decaying wood, and their diversity was lower. The abundance of polychaetes in decaying wood was negatively correlated with the number of individuals of Mollusca, Hexapoda and Crustacea. A change in the composition of polychaetes in decaying wood was found along the salinity gradient of this estuarine zone. Dissimilarities in the composition of benthic fauna in decaying wood and sediments in the Térraba mangrove showed that biodiversity was increased by the microhabitats inside the mangrove forest. Finally, several genera or species of polychaetes are new records for Costa Rica and the Central American Pacific Coast. Rev. Biol. Trop. 63 (Suppl. 1): 61-74. Epub 2015 April 01.

Resumen Este artículo presenta datos sobre los taxones de fauna, con énfasis en poliquetos; hallados en madera en descomposición y sedimentos. El estudio se realizó a través de un gradiente de salinidad dentro de un manglar estuarino de Costa Rica. Se capturaron los organismos destruyendo los leños encontrados en el piso del manglar Térraba. También, se sacó muestras de sedimento con un cilindro plástico. Se encontraron siete filos diferentes en las muestras del sedimento. De los 192 individuos encontrados, 18 eran poliquetos, con nueve familias y 11 especies. Al inspeccionar las muestras de madera en descomposición se encontró 2 564 individuos, distribuidos en cinco filos. Los poliquetos sumaron 429 individuos en ocho familias y 16 especies. Aunque los poliquetos fueron más abundantes en la madera deteriorada, su diversidad fue mayor en las muestras de sedimento. La abundancia de poliquetos en los leños se asoció negativamente con el número de individuos de Mollusca, Hexapoda y Crustacea. Se encontró que el gradiente de salinidad explica en gran medida el cambio en la composición de fauna. La disimilitud en la composición de fauna bentónica hallada en la madera deteriorada y los sedimentos en el manglar de Térraba, indicó que la biodiversidad aumenta al interior del manglar, gracias a la diversidad de micro hábitats. Finalmente varios géneros o especies de poliquetos son nuevos registros para Costa Rica y en general para la Costa Pacífica Centroamericana.

Depth diversity profile of polychaete worms in Bahía Chatham, Isla del Coco National Park, Costa Rican Pacific / Perfil de diversidad en profundidad de gusanos poliquetos en Bahía Chatham, Parque Nacional Isla del Coco, Pacífico costarricense

The subtidal benthos of tropical islands has been poorly studied in the Eastern Tropical Pacific. Several studies have been published on taxonomic collections from oceanic islands in the region, but ecological features and community structure are practically unknown. In the present study, composition of the polychaete community along a depth gradient from the sand bottom of Bahía Chatham, Isla del Coco National Park, Costa Rica is analyzed. Fifty species of polychaetes belonging to 28 families were found. There is a peak in diversity, abundance and richness at 28-30m. The lowest values occurred at 50m depth with values increasing below this depth. The composition of species changed with depth with some species being found only at depths either less than or greater than 50m. This pattern can be explained in part by the location of the thermocline that occurred at around 50m depth.

El bentos submareal de las islas tropicales ha sido poco estudiado en el Pacífico Oriental. Varios estudios se han publicado sobre colecciones taxonómicas de las islas oceánicas de la región, pero las características ecológicas y la estructura de la comunidad son prácticamente desconocidas. En el presente estudio se muestra la composición de la fauna de anélidos poliquetos según un gradiente de profundidad en los fondos arenosos de la Bahía de Chatham, Parque Nacional Isla del Coco, Costa Rica. Cincuenta especies de poliquetos repartidas en 28 familias fueron encontradas. La comunidad muestra un pico en la diversidad, abundancia y riqueza a los 28-30m. Los valores fueron menores a 50m mientras que por debajo de esta profundidad se observó una tendencia hacia un aumento en la riqueza de la comunidad. La composición de las especies cambió de acuerdo a la profundidad y algunas especies sólo se encontraron por debajo o por arriba de los 50m. La ubicación de la termoclina en la profundidad de 50m podría explicar en parte el patrón encontrado.

Crustaceans from a tropical estuarine sand-mud flat, Pacific, Costa Rica, (1984-1988) revisited

The availability of data sets for time periods of more than a year is scarce for tropical environments. Advances in hardware and software speed-up the re-analysis of old data sets and facilitates the description of population oscillations. Using recent taxonomic literature and software we have updated and re-analized the information on crustacean diversity and population fluctuations from a set of cores collected at a mud-sand flat in the mid upper Gulf of Nicoya estuary, Pacific coast of Costa Rica (1984-1988). A total of 112 morphological species of macroinvertebrates was found, of which 29 were crustaceans. Taxonomic problems, maily with the peracarids, prevented the identification of a group of species. The abundance patterns of the crab Pinnixa valerii, the ostracod Cyprideis pacifica, and the cumacean Coricuma nicoyensis were analized with the Generalized Additive Models of the free software R. The models evidenced a variety of population oscillations during the sampling period. These oscillations probably included perturbations induced by external factors, like the strong red tide events of 1985. In additon, early on 1984 the populations might have been at an altered state due to the inpact of El Niño 1982-83. Thus, the oscillations observed during the study period departed from the expected seasonality (dry vs rainy) pattern and are thus considered atypical for this tropical estuarine tidal-flat. Crustacean diversity and population peaks were within the range of examples found in worldwide literature. However, abundances of the cumacean C. nicoyensis, an endemic species, are the highest reported for a tropical estuary. Comparative data from tropical tidal flat crustaceans continues to be scarce. Crustaceans (total vs groups) had population changes in response to the deployment of predator exclusion cages during the dry and rainy seasons of 1985. Temporal and spatial patchiness characterized the abundances of P. valeri, C. pacifica and C. nicoyenis.

La disponibilidad de grupos de datos recolectados por periodos mayores a un año es escasa para ambientes marinos tropicales. Avances en hardware y software pueden acelerar el re-análisis de grupos antiguos de datos y facilitar la descripción de oscilaciones poblacionales ocultas. Mediante el uso de literatura taxonómica y programas de cómputo recientes actualizamos y re-analizamos la información sobre diversidad de crustáceos y oscilaciones poblacionales en un grupo muestras recolectadas con barreno en una planicie arenoso-fangosa en la región media superior del estuario del Golfo de Nicoya, costa Pacífica de Costa Rica (1984-1988). Se encontró un total de 112 morfo-especies de macro-invertebrados, de las que 29 fueron crustáceos. Problemas taxonómicos, especialmente con los peracáridos, impidieron la identificación completa de un grupo de especies. Las oscilaciones en la abundancia del cangrejo Pinnixa valerii, el ostrácodo Cyprideis pacifica, y el cumáceo Coricuma nicoyensis fueron analizadas con los Modelos Generales Aditivos (GAM) del programa de cómputo R de acceso libre. Los modelos evidenciaron una variedad de oscilaciones poblacionales durante el periodo de toma de muestras. Estas oscilaciones probablemente incluyen perturbaciones inducidas por factores externos, como los fuertes eventos de mareas rojas de 1985. Además, al inicio de 1984 las poblaciones podrían haber estado alteradas debido al impacto de El Niño 1982-83. Entonces, las oscilaciones observadas durante el estudio se alejan del patrón estacional (seco vs lluvioso) y son consideradas atípicas para esta planicie tropical estuarina arenoso-fangosa. La diversidad de crustáceos y las oscilaciones poblacionales fueron similares a las publicadas en la literatura mundial. Sin embargo, la abundancias del cumáceo Coricuma nicoyensis, una especie endémica, son las más altas informadas para un estuario tropical. Datos comparativos sobre planicies arenoso-fangosas en el trópico continúan siendo escasos. Los crustáceos (total vs grupos) tuvieron cambios poblacionales en respuesta a la colocación de jaulas con malla para excluir macro-depredadores durante las estaciones seca y lluviosa de 1985. Parches en el tiempo y el espacio caracterizaron a las abundancias de P. valeri, C. pacifica y C. nicoyenis.

Distribution of shallow water soft and hard bottom seabeds in the Isla del Coco National Park, Pacific Costa Rica / Distribución de fondos marinos de aguas someras de fondos blandos y duros en el Parque Nacional Isla del Coco, Pacífico de Costa Rica

Geographic Information Systems (GIS) applications used in marine habitats are powerful tools for management and monitoring of marine reserves and resources. Here, we present a series of maps of the soft and hard substrates in the shallow waters (>80 m depth) of Parque Nacional Isla del Coco (PNIC= Isla del Coco National Park). We use bathymetry data and field data as input for a GIS, GAM, and kriging methods to generate a series of maps that describe the bottom characteristics. Eight types of bottom were found in the PNIC by composition and grain size. The shore of the island and islets consisted of rocky formations (mainly basalts), with coral reefs in the subtidal of some areas. Rhodolith beds had a dispersing distribution. The bottom on the southern and southwestern region is hard substrate, while sediments cover the northern and northeastern zones. Slightly gravelly sand dominated the bays, while gravelly sand (with more coarse grains) was frequent offshore. The inner areas of Chatham and Wafer bays have mud and organic matter. The sediments in the area are mostly carbonates, except in Bahía Yglesias where clastic sediments (from the erosion of basalts) are presented. The information generated in this study could be a valuable input for future monitoring in the PNIC.

La aplicación de Sistemas de Información Geográfica (SIG), en los hábitats marinos es muy importante para la gestión y control de las reservas y recursos marinos. Aquí se presentan una serie de mapas de los sustratos sedimentarios y duros en las aguas poco profundas (> 80 m de profundidad) del Parque Nacional Isla del Coco (PNIC). Utilizamos datos de batimetría y datos de campo como entrada para un SIG, GAM, y los métodos de “kriging” para generar una serie de mapas que describen las características del fondo. ocho tipos de fondo marino se encuentran en el PNIC. La orilla de la isla y los islotes consistía de formaciones rocosas (principalmente basaltos), con arrecifes de coral en el submareal de algunas áreas. Las camas de rodolitos tienen una distribución dispersa. El fondo al sur y suroeste es dominado por sustratos duros, mientras que en el norte y noreste, principalmente por los sustratos sedimentarios. La arena algo gravosa dominó en las bahías, mientras que la arena gravosa lo fue fuera de la costa. Sólo en dos puntos, las zonas interiores de las bahías de Chatham y Wafer, se tiene la presencia de barro y mayor materia orgánica. Los sedimentos fueron altos en contenido de carbonatos, principalmente de color claro, pero en Bahía Yglesias el sedimento era oscuro, por ser arena volcánica producto de la erosión de los basaltos. Los mapas elaborados a partir del presente estudio pueden ser utilizados para el seguimiento futuro de los recursos marinos en PNIC.

Molluscan assemblage from a tropical intertidal estuarine sand-mud flat, Gulf of Nicoya, Pacific, Costa Rica (1984-1987)

The availability of data sets covering more than a year is scarce for tropical environments. Advances in hardware and software speed-up the re-analysis of old data sets and facilitates the identification of hidden data patterns. From February 1984 to April 1987 (49 sampling dates), core samples (17.7cm², 15cm deep) were collected at low tide at a sand-mud flat in the mid upper Gulf of Nicoya estuary, Pacific, Costa Rica. Predator exclusion experiments (cages 0.5x0.5x0.2m, galvanized wire, mesh size 5mm), were conducted at the site in 1985 (dry and rainy seasons sets). Samples were preserved with 5% buffered formalin in sea water stained with Rose Bengal, and washed after 24 hours on a 500 micron mesh sieve. The 1 120 cores yielded a total of 112 morphological species of which the mollusks were represented by 23 species, and included the bivalves Tellina rubescens, Tagelus bourgeoisae, Dosinia dunkeri and Leukoma asperrima, and the gastropods, Natica unifasciata, Nassarius luteostomus, Costoanachis rugosa and Turbonilla sp. The 23 species are indicative of a relatively rich sedimentary molluscan fauna. T. bourgeoisae had a seasonal oscillation, with higher abundancesduring the rainy seasons. T. rubescens was not seasonal, but presented an oscillation with peaks at about 1.5 year intervals. Many empty shells of Cosmioconcha modesta, lower number of N. luteostomus and a few of T. rubescens were found with boreholes by the predatory snail N. unifasciata. T. rubescens was not significantly more abundant inside or outside cages. T. bourgeoisae showed a significant increase within the caged areas. The numerical fluctuations of the mollusks became more important during the rainy season of 1985. Red tide outbreaks in the Gulf of Nicoya in 1985 may have had an impact on the molluscan populations. Rev. Biol. Trop. 59 (3): 1135-1148. Epub 2011 September 01.

La disponibilidad de datos con una cobertura mayor al año es rara para ambientes tropicales. Avances en computación y programas de cómputo facilitan el re-análisis de antiguos datos y la identificación de patrones ocultos en ellos. desde febrero de 1984 hasta abril de 1987 (49 fechas de colecta), muestras de barreno (17.7cm², 15cm de profundidad) fueron recolectadas durante la marea baja en una planicie arenosa-fangosa en la región media del estuario del Golfo de Nicoya, Costa Rica. Experimentos de exclusión de depredadores (jaulas 0.5x0.5x0.2m, malla galvanizada, poro de 5mm), fueron realizados en el sitio en 1985 (estación seca vs estación lluviosa). Las muestras fueron preservadas con formalina al 5% en agua de mar teñida con Rosa de Bengala y lavadas después de 24 horas en un tamiz de 500 micras de poro de malla. Los 1 120 barrenos produjeron un total de 112 especie morfológicas, de las cuales los moluscos estuvieron representados por 23 especies que incluyen los bivalvos: Tellina rubescens, Tagelus bourgeoisae, Dosinia dunkeri y Leukoma asperrima, y los gastrópodos, Natica unifasciata, Nassarius luteostomus, Costoanachis rugosa y Turbonilla sp. Las 23 especies son indicadoras de una fauna de moluscos relativamente rica. T. bourgeoisae presentó una oscilación estacional, con mayor abundancia durante la estación de lluvias. T. rubescens no fue estacional, pero presentó una oscilación con máximos a intervalos de cerca de 1.5 años. Muchas conchas vacías de Cosmioconcha modesta, un poco menos de N. luteostomus y unas pocas de T. rubescens fueron encontradas con perforaciones hechas por el depredador N. unifasciata. T. rubescens no fue significativamente más abundande dentro o fuera de las jaulas. T. bourgeoisae mostró una falta de abundancia estacional, pero una densidad significativamente mayor dentro de las jaulas. Las fluctuaciones poblacionales de los moluscos fueron más importantes durante la estación de lluvias cuando se les compara con las fluctuaciones de los poliquetos, crustáceos y otros grupos. Mareas rojas en el Golfo de Nicoya durante 1985 podrían haber tenido un impacto en la dinámica de las poblaciones de moluscos.

Comparación temporal de la composición y zonación de organismos en el intermareal rocoso del Parque Nacional Isla del Coco, Pacífico de Costa Rica

Temporal comparison of the composition and zonation of rocky intertidal organisms at Cocos Island National Park, Pacific, Costa Rica. Several biological and physical factors change the rocky shore communities. The desiccation time and the tolerance of the intertidal species produce the vertical zonation. In many studies around the world, a temporal change in this zonation is presented. In Costa Rica, only studies that include temporal trends were carried out in Punta Mala and Montezuma, Pacific coast in 80`s. The rocky intertidal of the Cocos Island National Park, Costa Rica were surveyed photographically. The Chatham bay was sampled in three expeditions (January 2007, October 2007 and April 2008). Photos corresponding to 25x25cm quadrats were taken with the goal to determine diversity and composition differences in rocky shore organisms between sampling dates. The Wafer bay was sampled in January and October 2007. The intertidal of Chatham consists of basaltic rock, while Wafer has basaltic and ignimbrite boulders. The main difference between sites were the higher algae cover (erect-frondose forms) and number of organism bands at Chatham bay. Temporal change was not found in the total cover of sessile fauna and autotrophs. The barnacle Tetraclita stalactifera, that occurs above the algal fringe (lower intertidal), was the invertebrate with the highest coverage. The mobile fauna biodiversity presented no significant trend between sampled months. However, the identity of species, their cover and their abundance showed a moderate temporal change. In October 2007, when the sea surface temperature was 23ºC the infralittoral zone had an increase in green algae cover. The red algae (crust and erect-frondose forms) were dominant in January and April. The pulmonate limpet, Siphonaria gigas and a bacterial biofilm at mid littoral showed a negative association. The snails of the high littoral and the supralittoral zone showed a temporal change in their abundance, but with contrasting patterns between sites. The temporal variation in the assemblages increased from the supralittoral to the infralittoral possibly due to changes in the water temperature and climatic conditions, that could influence the intertidal zone during the high and low tide, respectively. Rev. Biol. Trop. 58 (4): 1387-1403. Epub 2010 December 01.

La zona entre mareas rocoso de las bahías Chatham y Wafer en la Isla del Coco, Costa Rica fueron muestreadas fotográficamente con cuadrículas de 25x25cm en enero y octubre de 2007. Bahía Chatham también se visitó en abril 2008. El intermareal de Chatham estaba constituido por roca basáltica y en Wafer por basalto y cantos rodados de ignimbrita. Las principales diferencias entre sitios fueron las algas con mayor cobetura (erectas-frondosas) y el mayor número de bandas de organismos se dio en Chatham. No se encontró cambio temporal en la cobertura total de fauna sésil y de autótrofos. La mayor cobertura de invertebrados fue la del cirripedio Tetraclita stalactifera, siempre sobre la banda en la zona inferior de las algas. La diversidad de la fauna móvil no presentó tendencia significativa entre los meses de muestreo. Sin embargo, la identidad de las especies, cobertura o abundancia mostró un cambio temporal moderado. En octubre cuando el agua superficial del mar fue baja (23ºC), el infralitoral tuvo un incremento en la cobertura de las algas verdes. La dominancia en enero y abril fue de algas rojas (incrustantes y erectas-frondosas). Las lapas pulmonadas Siphonaria gigas y las cianobacterias del litoral medio mostraron una asociación negativa. Los caracoles de litoral alto y supralittoral presentaron un cambio temporal en su abundancia pero con diferentes patrones entre los sitios. Un incremento de variación en la composición de organismos se dio desde el supralitoral al infralitoral, posiblemente causado por el cambio en las condiciones del agua y el clima, que influyen en la zona entre mareas durante el alta y bajamar, respectivamente.