RESUMEN

Biological production and outgassing of greenhouse gasses (GHG) in Eastern Boundary Upwelling Systems (EBUS) are vital for fishing productivity and climate regulation. This study examines temporal variability of biogeochemical and oceanographic variables, focusing on dissolved oxygen (DO), nitrate, nitrogen deficit (N deficit), nitrous oxide (N2O) and air-sea N2O flux. This analysis is based on monthly observations from 2000 to 2023 in a region of intense seasonal coastal upwelling off central Chile (36°S). Strong correlations are estimated among N2O concentrations and N deficit in the 30-80 m layer, and N2O air-sea fluxes with the proportion of hypoxic water (4 < DO < 89 µmol L-1) in the water column, suggesting that N2O accumulation and its exchange are mainly associated with partial denitrification. Furthermore, we observe interannual variability in concentrations and inventories in the water column of DO, nitrate, N deficit, as well as air-sea N2O fluxes in both downwelling and upwelling seasons. These variabilities are not associated with El Niño-Southern Oscillation (ENSO) indices but are related to interannual differences in upwelling intensity. The time series reveals significant nitrate removal and N2O accumulation in both mid and bottom layers, occurring at rates of 1.5 µmol L-1 and 2.9 nmol L-1 per decade, respectively. Particularly significant is the increase over the past two decades of air-sea N2O fluxes at a rate of 2.9 µmol m-2 d-1 per decade. These observations suggest that changes in the EBUS, such as intensification of upwelling and the prevalence of hypoxic waters may have implications for N2O emissions and fixed nitrogen loss, potentially influencing coastal productivity and climate.

RESUMEN

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.

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.

Asunto(s)

RESUMEN

Understanding the drivers of geographical variation in species distributions, and the resulting community structure, constitutes one of the grandest challenges in ecology. Geographical patterns of species richness and composition have been relatively well studied. Less is known about how the entire set of trophic and non-trophic ecological interactions, and the complex networks that they create by gluing species together in complex communities, change across geographical extents. Here, we compiled data of species composition and three types of ecological interactions occurring between species in rocky intertidal communities across a large spatial extent (~970 km of shoreline) of central Chile, and analyzed the geographical variability in these multiplex networks (i.e., comprising several interaction types) of ecological interactions. We calculated nine network summary statistics common across interaction types, and additional network attributes specific to each of the different types of interactions. We then investigated potential environmental drivers of this multivariate network organization. These included variation in sea surface temperature and coastal upwelling, the main drivers of productivity in nearshore waters. Our results suggest that structural properties of multiplex ecological networks are affected by local species richness and modulated by factors influencing productivity and environmental predictability. Our results show that non-trophic negative interactions are more sensitive to spatially structured temporal environmental variation than feeding relationships, with non-trophic positive interactions being the least labile to it. We also show that environmental effects are partly mediated through changes in species richness and partly through direct influences on species interactions, probably associated to changes in environmental predictability and to bottom-up nutrient availability. Our findings highlight the need for a comprehensive picture of ecological interactions and their geographical variability if we are to predict potential effects of environmental changes on ecological communities.

Asunto(s)

RESUMEN

Se analizó la composición y abundancia del zooplancton de la laguna El Morro en la isla de Margarita, Venezuela, durante el periodo de surgencia (marzo-mayo 2011) y de relajación (junio-agosto 2011). Las muestras fueron recolectadas en 6 estaciones de las diferentes zonas de la laguna. Se realizaron calados con una red de plancton de 333 µm durante 10 minutos. Se midió in situ la temperatura, salinidad y oxígeno disuelto, además de nutrientes. Se registraron valores medios de temperatura de 29.7 ºC, salinidad de 36 ups, oxígeno disuelto de 5.9 mg.L-1. La concentración de nutrientes fue baja (medias de 0.12; 0.04; 0.03 mg.L-1 para nitrato, nitrito y fosfato, respectivamente). Se detectaron diferencias significativas temporales con mayores registros en la temporada de relajación, mientras que espacialmente no mostró diferencias, a pesar que en las estaciones internas (Est. 4,5,6) se obtuvo mayor abundancia. Se identificaron quince grupos zooplanctónicos, determinándose nueve especies del grupo Copepoda, dos de Cladocera, una de Decapoda, Tunicada y Rotifera y diferentes formas larvarias de distintos taxa. Las larvas de crustáceos presentaron la abundancia media y relativa más alta (47738 ind.m-3 y 46.83%, respectivamente), seguido del copépodo Oithona nana (31740 ind.m-3 y 25.94%, respectivamente) y Paracalanus quasimodo (12958 ind.m-3 y 8.47%, respectivamente). Esta laguna involucra la estacionalidad surgencia-relajación como un efecto importante en la distribución y abundancia del zooplancton.

The composition and abundance of the zooplankton of El Morro lagoon on the island of Margarita, Venezuela, during the upwelling period (March-May 2011) and relaxation (June-August 2011) were analyzed. Samples were collected at 6 stations in different areas of the lagoon. Sampling was performed with a 333 μm plankton net for 10 minutes. Water Temperature, salinity and dissolved oxygen were measured in situ, in addition to nutrients. Average water temperature values of 29.7 °C, a salinity of 36 ups, and dissolved oxygen of 5.9 mg.L-1 were found. The concentration of nutrients was low (averages of 0.12, 0.04, 0.03 mg.L-1 for nitrate, nitrite and phosphate, respectively). Significant seasonal differences were detected with greater records in the relaxation season, whereas spatially did not show differences, although in the internal stations a greater abundance was recorded. Fifteen zooplankton groups were identified, identifying nine species of Copepoda, two of Cladocera, one of Decapoda, Tunicada and Rotifera and different larval forms of different taxa. Crustacean larvae showed the highest average and relative abundance (47738 ind.m-3 y 46.83%, respectively), followed by copepod O. nana (31740 ind.m-3 and 25.94%, respectively) and P. quasimodo (12958 ind.m-3 and 8.47%, respectively). This lagoon involves the emergence-relaxation seasonality as an important effect on the distribution and abundance of zooplankton.

RESUMEN

In Tayrona National Natural Park (Colombian Caribbean), abiotic factors such as light intensity, water temperature, and nutrient availability are subjected to high temporal variability due to seasonal coastal upwelling. These factors are the major drivers controlling coral reef primary production as one of the key ecosystem services. This offers the opportunity to assess the effects of abiotic factors on reef productivity. We therefore quantified primary net (Pn ) and gross production (Pg ) of the dominant local primary producers (scleractinian corals, macroalgae, algal turfs, crustose coralline algae, and microphytobenthos) at a water current/wave-exposed and-sheltered site in an exemplary bay of Tayrona National Natural Park. A series of short-term incubations was conducted to quantify O2 fluxes of the different primary producers during non-upwelling and the upwelling event 2011/2012, and generalized linear models were used to analyze group-specific O2 production, their contribution to benthic O2 fluxes, and total daily benthic O2 production. At the organism level, scleractinian corals showed highest Pn and Pg rates during non-upwelling (16 and 19 mmol O2 m(-2) specimen area h(-1)), and corals and algal turfs dominated the primary production during upwelling (12 and 19 mmol O2 m(-2) specimen area h(-1), respectively). At the ecosystem level, corals contributed most to total Pn and Pg during non-upwelling, while during upwelling, corals contributed most to Pn and Pg only at the exposed site and macroalgae at the sheltered site, respectively. Despite the significant spatial and temporal differences in individual productivity of the investigated groups and their different contribution to reef productivity, differences for daily ecosystem productivity were only present for Pg at exposed with higher O2 fluxes during non-upwelling compared to upwelling. Our findings therefore indicate that total benthic primary productivity of local autotrophic reef communities is relatively stable despite the pronounced fluctuations of environmental key parameters. This may result in higher resilience against anthropogenic disturbances and climate change and Tayrona National Natural Park should therefore be considered as a conservation priority area.

RESUMEN

Invertebrates associated with the reef-building coral Pocillopora damicornis at Playa Blanca, Bahía Culebra, Costa Rica. The coral reefs are one of the most diverse ecosystems in the planet, not only because their reef-building species but also because of the species that live above, on, inside and below them. Corals of the genus Pocillopora are recognized globally by harboring an important fauna of invertebrates among their branches, many of those considered obligate symbionts. The present investigation describes the fauna of invertebrates associated with the reef-building coral P. damicornis in Bahía Culebra, Costa Rica, their densities, frequencies, richness and diversities from 2003 to 2004. Five coral colonies were collected every 3-4 months at Playa Blanca within Bahía Culebra. A total of 448 individuals in 35 species were found: Harpiliopsis depressa, Trapezia ferruginea, Alpheus lottini, Fennera chacei, and Petrolisthes haigae, and the bivalve Lithophaga aristata, the predominant species. November was the month with the highest richness, diversity and taxonomic distinctiveness, while August had the lowest values. In general terms, the rainy season showed greater richness of species than the dry season. The species collected and their densities and abundances were similar to other sites along the Eastern Tropical Pacific. Bahía Culebra has been losing coral cover, which could have consequences on the diversity and abundances of associated corals organisms. These consequences include loss in the fertility of those organisms, a reduction in its function as cleaners and protection from coral predators, putting in risk their diversity, affecting the stocks of predatory fish that depends on them. Carrying out permanent monitoring of the associated cryptofauna of the coral Pocillopora is crucial to quantify losses or recoveries in the composition of associated invertebrates, and therefore in the functions that they perform in this ecosystem.

Los arrecifes coralinos son uno de los ecosistemas más diversos en el planeta, tanto por los organismos constructores como por aquellos que viven encima, sobre, dentro y debajo de ellos. Los corales del genero Pocillopora son reconocidos mundialmente por albergar una importante fauna de invertebrados entre sus ramas, los cuales son considerados como simbiontes obligatorios en una gran cantidad de casos. La presente investigación describe la fauna de invertebrados asociados al coral Pocillopora damicornis en Bahía Culebra, Costa Rica, describiendo sus densidades, frecuencias, riquezas y diversidades a través del tiempo. Para esto se colectaron 5 colonias cada 3-4 meses en Playa Blanca, Bahía Culebra. En total se encontraron 448 individuos en 35 especies, siendo Harpiliopsis depressa, Lithophaga aristata, Trapezia ferruginea, Alpheus lottini, Fennera chacei, y Petrolisthes haigae las especies predominantes. Noviembre fue el mes en el que se encontraron los mayores valores en los índices de riqueza, diversidad y diferenciación taxonómica, mientras que agosto fue el que presento los valores más bajos de todos. En términos generales, la época lluviosa mostro mayor riqueza de especies que la época seca. Así mismo, las especies colectados y los valores obtenidos son muy similares a otras zonas del Pacifico Oriental Tropical. Culebra ha venido sufriendo una perdida en la cobertura coralina, que podría tener consecuencias en la diversidad y abundancia de organismos asociados a corales. Estas consecuencias incluyen perdida en la fecundidad de estos organismos, una reducción en su función como limpiadores y protectores de depredadores del coral, poniendo en riesgo su diversidad, lo que puede afectar los stocks de peces depredadores que depende de ellos. Realizar monitoreos permanentes de la criptofauna asociada al coral Pocillopora va a ser determinante para cuantificar perdidas o recuperaciones en la composición de invertebrados asociados, y por ende en las funciones que estos desempeñan en este ecosistema.

Asunto(s)