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Introduction: The study of the marine diversity of the North Pacific of Costa Rica began with isolated foreign expeditions in the 1930s and was systematically developed in the mid-1990s by the Center for Research in Marine Sciences and Limnology, Universidad de Costa Rica, as consequence there are now a total of 1 479 reported species in this region. Objective: Present an update to the echinoderm richness of the Guanacaste Conservation Area. Methods: We sampled 25 localities exhaustively and estimated similarity between sites based on the family richness and environmental heterogeneity. Results: We found 61 taxa, which represent 26 % of the echinoderm reported species for the country’s Pacific coast. Of these, 43 species are new records for the Guanacaste Conservation Area, and seven for Costa Rica and Central American Pacific coasts. We found three morpho-species that do not match to available descriptions of the Eastern Tropical Pacific echinoderm species. We also found the holothuroid Epitomapta tabogae, and the ophiuroid Ophioplocus hancocki, previously thought endemic to Panama and the Galapagos Islands, respectively. The proximity of the sampled sites and the redundancy of certain families may explain why we did not find important differences among localities. Conclusions: The echinoderm richness of this conservation area is at least 20 % higher than previously reported, reaching similar levels to those in other high diversity sites of the Eastern Tropical Pacific. Resumen Introducción: El estudio de la diversidad marina del Pacífico Norte de Costa Rica inició con expediciones extranjeras aisladas en la década de 1930, y fue desarrollado sistemáticamente a mediados de la década de 1990 por el Centro de Investigaciones en Ciencias del Mar y Limnología de la Universidad de Costa Rica, como consecuencia ahora se reporta un total de 1 479 especies en esta región. Objetivo: Presentar una actualización de la riqueza de equinodermos del Área de Conservación Guanacaste. Métodos: Realizamos muestreos exhaustivos en 25 localidades y estimamos la similitud entre sitios con base en la riqueaza de familias y la heterogeneidad ambiental. Resultados: Encontramos 61 taxa, que representan el 26% de las especies reportadas para la costa pacífica del país. De estas, 43 especies son nuevos registros para el Área de Conservación Guanacaste y siete para las costas de Costa Rica y el Pacífico centroamericano. Tres morfoespecies no coinciden con las descripciones disponibles para las especies del Pacífico Tropical Oriental. Por último, hallamos un ejemplar del holoturoideo Epitomapta tabogae y otro del ofiuroideo Ophioplocus hancocki, considerados endémicos para Panamá y las Islas Galápagos respectivamente. La proximidad entre los sitios muestreados y la redundancia de ciertas familias pueden explicar por qué no se encontraron diferencias entre las localidades. Conclusiones: La riqueza de equinodermos de esta área de conservación es al menos 20% mayor que la reportada anteriormente, alcanzando niveles similares a los de otros sitios de alta diversidad del Pacífico Tropical Oriental.

Resumen Introducción: Los hábitats costeros de todo el mundo están experimentando una presión cada vez mayor debido a la contaminación, el desarrollo costero, la pesca y el cambio climático. Identificar y registrar la biodiversidad costera es esencial para evaluar la salud, los cambios y el alcance de la pérdida de biodiversidad de los ecosistemas. Los hábitats costeros tropicales como los arrecifes de coral y los lechos de pastos marinos han sido el foco de investigación de los científicos durante las últimas décadas; sin embargo, se han descuidado otros ecosistemas, como los bosques de macroalgas, los fondos de sedimentos submareales (20-30 m de profundidad) y los arrecifes rocosos. Objetivo: Este trabajo reporta la biodiversidad marina asociada con arrecifes rocosos, arrecifes de coral, bosques de Sargazo y fondos submareales sedimentarios (20-30 m de profundidad), en un área tropical de afloramiento estacional (Península de Santa Elena, Bahía de Santa Elena e Islas Murciélago, Costa Rica). Métodos: Durante la Expedición Santa Elena (21 de abril-2 de mayo de 2018), se visitaron un total de 28 sitios para registrar la biodiversidad en cuatro hábitats diferentes (arrecifes rocosos y de coral, bosques de sargazo y fondos de sedimentos submareales), utilizando SCUBA, en muestreos sistemáticos, evaluaciones visuales y en algunos fondos de sedimentos se utilizó una draga de arrastre por 20 minutos. Resultados: Se identificaron un total de 254 taxones, siendo los peces óseos el grupo más diverso con 91 especies, seguido de los gasterópodos (25 spp.), las algas rojas (21 spp.) y los antozoos (19 spp.). Se reportan cuatro nuevos registros para el Pacífico continental de Costa Rica, incluida la subclase de una anémona tubícola (Ceriantharia). Conclusiones: Los resultados muestran que la península de Santa Elena, la bahía de Santa Elena y las islas Murciélago albergan hábitats poco comunes y no estudiados, como bosques del alga parda Sargassum, fondos de sedimentos, arrecifes construidos por el coral masivo Pavona gigantea, que es muy inusual, y comunidades de arrecifes rocosos dominadas por colonias calcáreas de poliquetos (Salmacina tribranchiata). Abstract Introduction: Worldwide, coastal habitats are experiencing increasing pressure from pollution, coastal development, fisheries, and climate change. Identifying and recording coastal biodiversity is essential to assess ecosystem health, changes and the extent of biodiversity loss. Coastal tropical habitats such as coral reefs and seagrass beds have been the research focus for scientists during the last decades; however, other ecosystems have been neglected, such as macroalgae forests, subtidal (20-30 m deep) sedimentary bottoms, and rocky reefs. Objective: Our study reports the marine biodiversity associated with rocky reefs, coral reefs, Sargassum forests and sedimentary subtidal bottoms (20-30 m deep), in a tropical seasonal upwelling area (Santa Elena Peninsula, Santa Elena Bay, and Murciélago Islands, Costa Rica). Methods: During the ‘Santa Elena Expedition’ (April 21-May 2 2018), a total of 28 sites were visited in order to record the biodiversity across four different habitats (rocky and coral reefs, Sargassum forests, subtidal sedimentary bottoms), using SCUBA and both systematic surveys and visual assessments; in some sedimentary bottoms a 20-minute dredge tows were done. Results: A total of 254 taxa were identified, being bony fishes the most diverse group (91 species), followed by gastropods (25 spp.), red algae (21 spp.) and anthozoans (19 spp.). We report four new records for the Pacific mainland of Costa Rica, including the subclass of tube-dwelling sea anemone (Ceriantharia). Conclusions: Our results show that Santa Elena Peninsula, Santa Elena Bay, and Murciélago Islands harbor uncommon and unstudied habitats, such as Sargassum forests, sedimentary bottoms, reefs constructed by the stony coral Pavona gigantea -which is very unusual- and rocky reef communities dominated by calcareous colonies of polychaetes (Salmacina tribranchiata).

The present study compares the ecological patterns of macrofauna in sandy beaches between the Caribbean and Pacific coasts of Costa Rica. At each beach, the intertidal zone was divided into five strata from low to high tide level. In each stratum, sediment samples (corer area: 20.2 cm2, diameter: 5.07 cm) were collected to analyze the macrofauna. Additionally, grain size composition, total organic matter and carbonates of the sediments were determined. The macrofauna diversity was higher in the Pacific coast (15 taxa, per beach) than in the Caribbean (4 taxa, per beach). The most diverse taxon group was the annelids, followed by arthropods and mollusks. Within the mollusks, the bivalves and the gastropod family Olivellidae were only present in the Pacific coast. Both Caribbean and Pacific coasts had a vertical zonation of taxa distribution from high to low tide level. Typically, the low tide level was populated by several polychaetes, mid littoral by crustacean and mollusks, and the high tidal level was populated by isopods (Cirolanidae). Faunal differences in richness, abundance and composition of assemblages between both coasts can be explained by environmental differences. The tidal range is narrower on the Caribbean (0.5–1.5 m) than the Pacific coast (2–3 m). The slope of the beach is steep in several beaches of the Caribbean, whereas the Pacific has several dissipative beaches with gentle (or flat) slopes. The organic matter was lower (1.00%) in the Caribbean than in the Pacific (2.25%). In the Caribbean coast, the sediment is ∼90% fine sand (500–63 μm), while in the Pacific this fraction was ∼65%, resulting in more heterogeneous sediments in the Pacific. Finally, evidence of change in the abundance and species composition with the latitude in each coast was detected; indicating that these communities are highly variable within a local scale, which could be due to the diversity of sandy beaches and environmental variation that Costa Rica has in both coasts. Our results indicate that beaches with higher number of species or abundance were not necessarily designated as Marine Protected Areas. This information should be considered in the future for the establishment of new Marine Protected Areas.

The southern banded guitarfish, Zapteryx xyster, and the Velez ray, Raja velezi, are two endemic elasmobranchs in the eastern Tropical Pacific that are commonly caught by the bottom-trawl fishery. Reproductive cycles of these batoids were inferred from the hepatosomatic and gonadosomatic indexes (males and females) and the oviductal gland width and the yolk follicle diameter (females) of mature specimens collected along the Pacific of Costa Rica between 2010 and 2011. Z. xyster females have a partially defined annual cycle with one reproductive peak in June and July, with most neonates and gravid females occurring during December and January (beginning of the dry season). The gestation period of Z. xyster can range between four and six months; males are probably capable of mating continuously throughout the year. Females and males of R. velezi have a continuous reproductive cycle with no clear peaks. Management and conservation measures of these batoids should consider their reproductive ecology, which may be linked to the degree of vulnerability to fishing. Based on our findings, we recommend reducing fishing pressure when mating (June-July) and pupping (December-January) of Z. xyster occur. In contrast, a reduction of fishing pressure on previously identified nursery grounds of R. velezi in the southern Pacific of Costa Rica may benefit their population.

Decapod crustaceans are a diverse group that exploits various types of habitats in Costa Rica, where they represent 8.1% of the marine diversity of the country. This group includes families containing species with strictly symbiotic behavior, e.g., the Palaemonidae and Pinnotheridae. Despite the high diversity of decapods and the importance of symbionts in marine ecosystems, very little research has been done regarding symbiosis in Costa Rica and the Central American region. The objective of the present study is to present a check list of the species of decapods that are associated with macroinvertebrates in Pacific Costa Rica. The research was carried out using different sources, including a literature review, the Crustaceans Collection of the Zoology Museum of the University of Costa Rica, and field surveys between 1970 and 2019 along the Pacific coast of Costa Rica, and Isla del Coco, 500 km offshore. One-hundred associations are reported, of 74 species of symbiotic decapods with six host phyla. Seventy-four associated with Cnidaria, 15 with Echinodermata, four each with Annelida and Mollusca, two with Chordata, and one with Porifera. In total, there were 14 new reports of decapods occurring on Isla del Coco and four new reports of decapods for Costa Rica: Pseudocoutierea elegans, Raytheres clavapedatus, Tuleariocaris holthuisi, and Calyptraeotheres pepeluisi. These results highlight the need to conduct more detailed studies to determine the real diversity and ecological importance of the associations between marine organisms. Universidad de Costa Rica/[808-B6–520]/UCR/Costa Rica Universidad de Costa Rica/[808-B3–503]/UCR/Costa Rica Universidad de Costa Rica/[808-A5–037]/UCR/Costa Rica Universidad de Costa Rica/[808–98-013]/UCR/Costa Rica UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biodiversidad y Ecología Tropical (CIBET)

The crayfish plague pathogenAphanomyces astaciis one of the main factors responsible for the decline in European and Asian native crayfish species. This pathogen was transported to these regions through its natural carriers, North American crayfish species, which were introduced during the last century. Since then, the carrier species and the pathogen have spread worldwide due to globalization and the highly invasive nature of these species. In Europe, five carrier species have been categorized as high-risk as they are responsible for the loss of provisioning services, which endangers freshwater ecosystems. The red swamp crayfishProcambarus clarkii, in particular, is currently one of the most concerning species as its spread threatens crayfish biodiversity and freshwater ecosystems worldwide. In this study, we describe the first detection ofA. astaciin an introduced population ofP. clarkiiin Central America, specifically in Costa Rica. Using molecular approaches, we analyzed 48 crayfish samples collected from Reservoir Cachí and detected the presence ofA. astaciin four of these samples. The introduction ofP. clarkiiand the incorrect management of the species (related to its fishery and the commercialization of live specimens) over the past decades in Europe are mistakes that should not be repeated elsewhere. The detection of the pathogen is a warning sign about the dangerous impact that the introduction of this invasive crayfish may have, not only as a carrier of an emerging disease but also as a direct risk to the invaded ecosystems. Our results may serve to (1) assess current and future consequences, and (2) direct future research activities, such as determining the potential impacts ofA. astacion native decapod species, or on other introduced crayfish species that are used for aquaculture purposes, such asCherax quadricarinatus.

We report on 13 species collected during the 1973 expedition onboard the MY “Velero IV”: seven Euphausiidae (krill), two Benthesicymidae shrimp, two Sergestidae shrimp, one Acanthephyridae shrimp, and one Portunidae crab. Four species are new records for Costa Rica: Bentheogennema burkenroadi, Gennadas scutatus, Neosergestes consobrinus, and Phorcosergia filicta En este estudio reportamos 13 especies recolectadas durante la expedición de 1973 a bordo del MY “Velero IV”, siete krill Euphausiidae, dos camarones Benthesicymidae, dos camarones Sergestidae, un camarón Acanthephyridae, y un cangrejo Portunidae. Cuatro especies son nuevos reportes para Costa Rica: Bentheogennema burkenroadi, Gennadas scutatus, Neosergestes consobrinus, y Phorcosergia filicta. UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biodiversidad y Ecología Tropical (CIBET) UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR)

Studies of the bycatch associated to the shrimp trawling fishery in the Pacific coast of Costa Rica do not assess small organisms (< 10 cm TL) and non-dominant species (< 0.1% of total catch). There is a void in assessing the maintenance of the ecology and ecosystem on which the fishery depends. Furthermore, the Constitutional Court of Costa Rica prohibited the renewal of existing and the issuing of new shrimp bottom-trawl licenses, indicating the necessity of more scientific information on the impacts of this fishery. We present the results of a 23-month study of the shrimp bottom-trawl fishery performed between 50 and 350 m deep in the Pacific coast of Costa Rica. A total of 109 hermit crabs were collected (six species and two families). Paguristes cf. holmesi was the most common species. Zone II presented the highest species richness and abundance. Most specimens (81.8 %) were caught in shallower waters (50-149 m). More than 45% of the trawls presented hermit crabs. It is imperative to further assess the trawling effects on non-commercial benthic fauna and changes on predator-prey relationships before issuing new shrimp licenses

Background Acanthurus guttatus is distributed from the Maldives to the Hawaiian Archipelago and the Pitcairn Islands, and as north as Ryukyu Islands and as south as New Caledonia. The only known locality in the Eastern Tropical Pacific is Clipperton Atoll where three vagrant specimens have been observed. Methods On June 2016 and April 2017 small groups of A. guttatus were observed and photographed during SCUBA diving and snorkeling surveys for touristic suitability at Isla del Coco National Park, Costa Rica. Results Six specimens of A. guttatus were observed swimming over shallow rocky reefs at Isla del Coco, a volcanic island located in the Eastern Tropical Pacific. Conclusions This study represents the first record of A. guttatus at Isla del Coco, the second known location of occurrence in the Eastern Tropical Pacific, and the easternmost known range for the Whitespotted surgeonfish.

Crustaceans are an important component of deep-sea biodiversity. A brief review of the history of expeditions and studies related to deep-sea crustaceans in Costa Rica is presented. We briefly discuss studies on crustaceans from the Costa Rican deep-sea environments, and we provided an updated list of species recorded for the Pacific and the Caribbean. A total of 147 species has been reported from Costa Rican deep sea; 8 species have been reported from the Caribbean, 138 from the Pacific, and 1 from both basins. Decapoda was the most diverse group with 87 species, followed by Copepoda (23 spp.) and Peracarida (19 spp.). The first deep-sea exploration in Costa Rica began with foreign efforts, with national projects and participation increasing in recent years. Most research dealing with crustaceans has been focused on reproductive biology, in collaboration with the deepwater shrimp fisheries. Future efforts to study the Costa Rican deep-sea will incorporate collaboration with foreign expeditions and private companies since the country does not have enough funding invested in its deep sea. Finally, we discuss the current threats to deep-sea crustaceans, as well as future perspectives for the study of this fascinating group in Costa Rica.

Isla del Coco (Costa Rica) forms part of the five oceanic islands of the Eastern Tropical Pacific and is well known for its high biodiversity and great endemism. While several marine biological and oceanographical surveys have been conducted around the island over the past 35 years, an integrated, systematic view of the shallow water system is lacking as is an assessment of the impact of illegal fisheries. The aim of the study was thus to identify the main biological compartments of the Isla del Coco system and to quantify its energy flow structure through the development of a trophic model for the shallow water environments (≤30 m). With the software Ecopath with Ecosim, and based on the model structure previously used for Darwin and Wolf islets in the Galápagos Archipelago, a trophic model was developed using information from several field surveys and additional data from similar systems. The total biomass of the Isla del Coco system (1,972.25 t km−2) was mainly comprised of high trophic level species such as hammerhead shark, pelagic predatory fish and other sharks. The reef ecosystem is in a healthy (relatively undisturbed) state and dominated by large apex predators and mesopredators. Of the keystone groups identified (toothed cetaceans, tiger sharks, other sharks, benthic omnivorous fish and pelagic predatory fish), toothed cetaceans and tiger sharks were identified as having the strongest influence on the structure and diversity of the community through direct and indirect interactions. The Isla del Coco ecosystem presents a higher biomass than a similar system in the Galápagos archipelago, likely due to lower fishing pressure and higher system maturity. UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biología

Euphausiids have been well studied in several regions of the Pacific Ocean; however, there is less information regarding euphausiids in Costa Rican waters. We analyzed euphausiid specimens collected around Isla del Coco National Park during 2011 and 2012. A total of 130 specimens were analyzed and 13 euphausiid species were identified, belonging to four genera and one family. An annotated list of species is presented, with photographs and details for their identification. All species found represent new records for waters around Isla del Coco in the Costa Rican Pacific. The most frequent species were Euphausia diomedeae, Euphausia distinguenda, Nematoscelis gracilis and Stylocheiron affine. Los eufáusidos han sido ampliamente estudiados en el Océano Pacífico, sin embargo existe poca información respecto a los eufáusidos que habitan aguas costarricenses. Analizamos 130 especímenes de eufáusidos provenientes de muestras de zooplancton recolectadas alrededor de la Isla del Coco del 2011 y 2012. Identificamos 13 especies pertenecientes a cuatro géneros y una familia. Se presenta un listado de especies y fotografías con detalles que facilitan su identificación. Todas las especies encontradas representan nuevos informes para aguas de la Isla del Coco en el Pacífico costarricense. Las especies más frecuentes fueron Euphausia distinguenda, Nematoscelis gracilis, Euphausia diomedeae y Stylocheiron affine. Consejo Nacional de Rectores/[]/CONARE/Costa Rica Universidad de Costa Rica/[808-B0-654]/UCR/Costa Rica Universidad de Costa Rica/[808-B0-060]/UCR/Costa Rica UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biología

The Galapagos Slipper lobster, Scyllarides astori, has been reported from rocky reefs along the Eastern Tropical Pacific: the Gulf of California, the Galapagos Archipelago and mainland Ecuador. Although larval stage S. astori has been found in other localities throughout this range, there are no records of adults inhabiting waters between these three locations. Here we present the first record of an adult S. astori from Isla del Coco and Costa Rican Pacific waters. The single specimen, a male, was hand-collected within a coral reef in Pajara islet. This finding increases the reported lobster species richness of Costa Rican Pacific waters to six species and expands the adult geographic range of S. astori to Isla del Coco.

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.

Marine macroalgae are highly diverse and play an important role in marine ecosystems, influencing ecological processes. Recording the algae diversity with precise taxonomic identification is required to understand the marine ecosystems. The biodiversity of macroalgae along the southern Caribbean coast of Costa Rica has been studied by several authors, and the updated checklist includes 396 species of benthic marine algae reported for both Pacific and Caribbean coasts of Costa Rica, from which 287 are recorded from the Caribbean. Eighty percent of the total specimens from the Caribbean coast deposited in botanical collections in Costa Rica were collected at Cahuita National Park, an area where most of the studies have been carried out. This study reports on the addition of five new species and one genus of marine benthic macroalgae to the Caribbean Costa Rican flora, found at the poorly studied reefs of Playa Chiquita (Punta Cocles) and Punta Uva. Sampling was directed, searching for benthic macroalgae at Chiquita beach (SCUBA diving and snorkel) and Punta Uva (snorkel only), during October 2014. Specimens were deposited in the Dr. Luis A. Fournier Origgi Herbarium of the University of Costa Rica (USJ). Most of the new records were Chlorophyta, followed by Rhodophyta and Ochrophyta-Phaeophyceae. We recorded four new genera for the Caribbean coast of Costa Rica: Microdictyon Decaisne, 1841, Rhipidosiphon Montagne, 1842, Predaea G. De Toni, 1936, and Augophyllum S.-M. Lin, S. Fredericq & M. H. Hommersand, 2003. In conclusion, is necessary to continue the detailed taxonomic works in the Caribbean coast, focusing on areas poorly studied, in order to improve our knowledge of the marine flora of Costa Rica. Rev. Biol. Trop. 66(Suppl. 1): S328-S339. Epub 2018 April 01.