Jeffrey A. Sibaja-Cordero

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 LPAs benthos.

Polychaetes (Annelida: Polychaeta) of Cocos Island National Park, Pacific Costa Rica

Abstract: An extensive collecting effort resulted in identification of 106 species of polychaetes from the intertidal and shallow subtidal of Isla del Coco, Costa Rica. One hundred and three of the species reported here are new records. Only two species had not been previously collected from the Pacific coastline between Mexico and Chile. Transport of polychaetes to the island either as larvae, adults, or by rafting is discussed. Comparisons are made with the less well-analyzed polychaete fauna of the Galapágos Islands, with lower species richness on the smaller and ecologically less variable Isla del Coco. Relative lack of isolation between the polychaetes of Isla del Coco and the mainland is discussed.

Marine Biodiversity of Eastern Tropical Pacific Coral Reefs

The eastern tropical Pacific (ETP) is an isolated oceanic region exposed to extreme oceanographic conditions, including low salinity, low pH, high temperatures during El Nino, and low temperatures during La Nina and seasonal upwelling. The coral reefs in this region have a relatively limited suite of species compared to other coral reef areas of the world, but much like more diverse reefs the species present interact in complex ways. Here we synthezise the knowledge of taxonomic groups of reef organisms from prokaryotes to vertebrates, including algae, sponges, cnidarians, annelids and other worms, molluscs, crustaceans, echinoderms and fishes. We also present summaries on the biodiversity of associated functional groups and habitats, including (a) reef zooplankton and cryptic fauna, and (b) soft benthic environments, rhodolith beds and mesophotic environments. Several factors that structure the biodiversity of ETP coral reefs are explored, including biological, physical and chemical controls. ETP coral reefs are relatively simple systems that can be used as models for studying biodiversity and interactions among species. We conclude this review by highlighting pressing research needs, from very basic inventories to more sophisticated studies of cryptic assemblages, and to investigations on the impacts of natural and anthropogenic effects on ETP coral reef biodiversity.

The Lancelet Asymmetron lucayanum Complex in Cocos Island National Park, Pacific Costa Rica

Abstract: The lancelet Asymmetron lucayanum complex was collected from subtidal (5–42 m) sandy bottom during a benthic survey designed to describe the biota of Cocos Island National Park (Parque Nacional Isla del Coco), Costa Rica, a World Heritage Site. Taxonomically significant characters of A. lucayanum (number of myotomes, gonads only on the right side of the body, shape of metapleural folds) are discussed. These lancelets were living in poorly sorted and slightly gravelly sand. Although this taxon has a circumtropical distribution, this is the first time it has been collected anywhere in the eastern Pacific.

Recent surface marine sediments of Cocos Island in Costa Rica

Abstract Subtidal sediments of Isla del Coco (Cocos Island), Costa Rica were described in their grain size, sorting, organic matter, and carbonates from 27 dredge samples (3–75 m), collected in April 2010. The organic matter range between 1.37–3.31% and carbonates presented a mean of 74±17%. The sorting was moderately or poorly. The grain size ranged between 0.1–1.1mm. The pattern is that sediment change from inner to mouth of bays. Carbonates and gravel fractions increased offshore and organic matter have high values inner the bays. Input of vegetal debris and mud was from the rivers of this island covered with rain and cloud forest.

Occurrence of the Phoronid Phoronopsis albomaculata in Cocos Island, Costa Rica

Abstract: The phoronid Phoronopsis albomaculata was collected in subtidal (28–35 m) sandy sediments in Bahía Chatham during a benthic survey designed to describe the biota of Cocos Island (Isla del Coco), Costa Rica, a national park and Human Heritage Site. Occurrence of this widespread species in Cocos Island is the first report of a phoronid for Costa Rican waters and is the second locality recorded for the eastern Pacific. Taxonomically significant characters (presence of an epidermal collar, extent of coiling of lophophore and nephridia) are discussed. Comparisons are made between depth and abundance of this species from Cocos Island and results of previous studies.

Invertebrate species richness in sandy beaches and rocky coast of Costa Rican North Pacific.

Este estudio resume informacion publicada sobre las especies de invertebrados reportadas para la zona intermareal de la costa rocosa y las playas de arena del Pacifico Norte de Costa Rica. Ademas, se presentan datos nuevos sobre la riqueza de especies de la comunidad de invertebrados de varias playas de areas protegidas o no protegidas muestreadas durante el ano 2012. Los resultados indican una amplia variacion en el numero de especies reportadas, siendo los principales contribuyentes a la fauna los moluscos, crustaceos y poliquetos. El numero de especies dependio del grupo faunistico y el esfuerzo de muestreo de los estudios previamente realizados. Teniendo en cuenta, todos los componentes de la comunidad, se encontraron entre 29 a 175 especies en los intermareales rocosos, y de 5 a 15 especies en las playas de arena. El valor promedio de riqueza de especies fue similar entre las areas protegidas y no protegidas, aunque en ambos casos el rango de valores fue muy amplio. Hay lugares con gran riqueza de especies, sin medidas de proteccion, que estan actualmente expuestos a los impactos del desarrollo de las poblaciones humanas, y es ahi donde urge la gestion de dichos habitats

Occurrence, Demography, and Habitat Features of Pollicipes elegans (Pollicipedidae: Scalpelliformes), an Amphitropical Species at a Rocky Intertidal Shore, Costa Rica

Abstract: Clumps of the gooseneck barnacle Pollicipes elegans were found in the central Pacific on a rocky shore of Costa Rica. This species is known to be abundant in northern and southern latitudes of the eastern tropical Pacific. This study describes aspects of its demography and size structure, as well as habitat features in Costa Rica. The clumps were generally on vertical rocky substrates, with a negative slope and an average height of 1.70 m above the Lowest Astronomical Tide. Two cohorts were found on the rocky shore in 2014. An important decline of abundance and density of clumps was found between July and October of 2014. Additional clumps were found in September 2016. We present hypotheses about how this species became established in Costa Rica and why a decline of the clumps was observed.