Reducing Gut Dissolution of Zinc Oxide Nanoparticles by Secondary Microplastics with Consequent Impacts on Barnacle Larvae.

The environmental impact of sunscreen is a growing concern, yet the combined effects of its components on marine animals are poorly understood. In this study, we investigated the combined effects of sunscreen-extracted zinc oxide nanoparticles (nZnO) and microplastics (MPs) on the development of barnacle larvae, focusing on the different roles played by primary microplastics (PMPs) and secondary microplastics (SMPs) generated through the phototransformation of PMPs. Our findings revealed that a lower concentration of nZnO (50 µg/L) enhanced molting and eye development in barnacle larvae, while a higher concentration (500 µg/L) inhibited larval growth. Co-exposure to PMPs had no significant effect on larval development, whereas SMPs mitigated the impact of nZnO by restricting the in vivo transformation to ionic Zn. Accumulated SMPs reduced gut dissolution of nZnO by up to 40%, lowering gut acidity by 85% and buffering the in vivo dissolution of nZnO. We further identified a rough-surfaced Si-5 fragment in SMPs that damaged larval guts, resulting in decreased acidity. Another Si-32 resisted phototransformation and had no discernible effects. Our study presented compelling evidence of the impacts of SMPs on the bioeffect of nZnO, highlighting the complex interactions between sunscreen components and their combined effects on marine organisms.

Genome-wide phylogeography reveals cryptic speciation in the circumglobal planktonic calcifier Limacina bulimoides.

Little is known about when and how planktonic species arise and persist in the open ocean without apparent dispersal barriers. Pteropods are planktonic snails with thin shells susceptible to dissolution that are used as bio-indicators of ocean acidification. However, distinct evolutionary units respond to acidification differently, and defining species boundaries is therefore crucial for predicting the impact of changing ocean conditions. In this global population genomic study of the shelled pteropod Limacina bulimoides, we combined genetic (759,000 single nucleotide polymorphisms) and morphometric data from 161 individuals, revealing three major genetic lineages (FST = 0.29-0.41): an "Atlantic lineage" sampled across the Atlantic, an "Indo-Pacific lineage" sampled in the North Pacific and Indian Ocean, and a "Pacific lineage" sampled in the North and South Pacific. A time-calibrated phylogeny suggests that the lineages diverged about 1 million years ago, with estimated effective population size remaining high (~10 million) throughout Pleistocene glacial cycles. We do not observe any signatures of recent hybridization, even in areas of sympatry in the North Pacific. While the lineages are reproductively isolated, they are morphologically cryptic, with overlapping shell shape and shell colour distributions. Despite showing that the circumglobal L. bulimoides consists of multiple species with smaller ranges than initially thought, we found that these pteropods still possess high levels of genetic variability. Our study adds to the growing evidence that speciation is often overlooked in the open ocean, and suggests the presence of distinct biological species within many other currently defined circumglobal planktonic species.

Single substance and mixture toxicity of dibutyl-phthalate and sodium dodecyl sulphate to marine zooplankton.

Several contaminants exceed their environmental thresholds in Swedish marine surface waters. We ranked the toxicity-drivers among contaminants detected near heavy industry, based on toxicity to zooplankton, and identified di-butyl phthalate and sodium dodecyl sulphate as contaminants of concern. We tested their acute individual and mixture toxicity by assessing effects on mortality, biodiversity, algal growth, and copepod reproduction in natural mesozooplankton communities. The mixture effects were compared to Independent Action mixture model predictions. Egg production and algae growth were affected at 4 µmol/l DBP, and effects on mortality, algae growth and biodiversity were observed at 12 µmol/l SDS. The mixture (1 µmol/l DBP, 3 µmol/l SDS) affected all endpoints, and the observed effects were underestimated by 21% on average compared to predictions. We found that the successional trajectory in zooplankton communities was compound dependant, and that DBP and SDS are toxic to marine zooplankton, but at levels above measured environmental concentrations.

Linezolid Resistance Genes in Enterococci Isolated from Sediment and Zooplankton in Two Italian Coastal Areas.

Linezolid is a last-resort antibiotic for the treatment of severe infections caused by multidrug-resistant Gram-positive organisms; although linezolid resistance remains uncommon, the number of linezolid-resistant enterococci has increased in recent years due to worldwide spread of acquired resistance genes (cfr, optrA, and poxtA) in clinical, animal, and environmental settings. In this study, we investigated the occurrence of linezolid-resistant enterococci in marine samples from two coastal areas in Italy. Isolates grown on florfenicol-supplemented Slanetz-Bartley agar plates were investigated for their carriage of optrA, poxtA, and cfr genes; optrA was found in one Enterococcus faecalis isolate, poxtA was found in three Enterococcus faecium isolates and two Enterococcus hirae isolates, and cfr was not found. Two of the three poxtA-carrying E. faecium isolates and the two E. hirae isolates showed related pulsed-field gel electrophoresis (PFGE) profiles. Two E. faecium isolates belonged to the new sequence type 1710, which clustered in clonal complex 94, encompassing nosocomial strains. S1 PFGE/hybridization assays showed a double (chromosome and plasmid) location of poxtA and a plasmid location of optrA Whole-genome sequencing revealed that poxtA was contained in a Tn6657-like element carried by two plasmids (pEfm-EF3 and pEh-GE2) of similar size, found in different species, and that poxtA was flanked by two copies of IS1216 in both plasmids. In mating experiments, all but one strain (E. faecalis EN3) were able to transfer the poxtA gene to E. faecium 64/3. The occurrence of linezolid resistance genes in enterococci from marine samples is of great concern and highlights the need to improve practices aimed at limiting the transmission of linezolid-resistant strains to humans from environmental reservoirs.IMPORTANCE Linezolid is one of the few antimicrobials available to treat severe infections due to drug-resistant Gram-positive bacteria; therefore, the emergence of linezolid-resistant enterococci carrying transferable resistance determinants is of great concern for public health. Linezolid resistance genes (cfr, optrA, and poxtA), often plasmid located, can be transmitted via horizontal gene transfer and have the potential to spread globally. This study highlights the detection of enterococci carrying linezolid resistance genes from sediment and zooplankton samples from two coastal urban areas in Italy. The presence of clinically relevant resistant bacteria, such as linezolid-resistant enterococci, in marine environments could reflect their spillover from human and/or animal reservoirs and could indicate that coastal seawaters also might represent a source of these resistance genes.

Response of the copepod Acartia tonsa to the hydrodynamic cues of small-scale, dissipative eddies in turbulence.

This study quantifies the behavioral response of a marine copepod (Acartia tonsa) to individual, small-scale, dissipative vortices that are ubiquitous in turbulence. Vortex structures were created in the laboratory using a physical model of a Burgers vortex with characteristics corresponding to typical dissipative vortices that copepods are likely to encounter in the turbulent cascade. To examine the directional response of copepods, vortices were generated with the vortex axis aligned in either the horizontal or vertical direction. Tomographic particle image velocimetry was used to measure the volumetric velocity field of the vortex. Three-dimensional copepod trajectories were digitally reconstructed and overlaid on the vortex flow field to quantify A. tonsa's swimming kinematics relative to the velocity field and to provide insight into the copepod behavioral response to hydrodynamic cues. The data show significant changes in swimming kinematics and an increase in relative swimming velocity and hop frequency with increasing vortex strength. Furthermore, in moderate-to-strong vortices, A. tonsa moved at elevated speed in the same direction as the swirling flow and followed spiral trajectories around the vortex, which would retain the copepod within the feature and increase encounter rates with other similarly behaving Acartia While changes in swimming kinematics depended on vortex intensity, orientation of the vortex axis showed minimal significant effect. Hop and escape jump densities were largest in the vortex core, which is spatially coincident with the peak in vorticity, suggesting that vorticity is the hydrodynamic cue that evokes these behaviors.

Novel genomic resources for shelled pteropods: a draft genome and target capture probes for Limacina bulimoides, tested for cross-species relevance.

BACKGROUND: Pteropods are planktonic gastropods that are considered as bio-indicators to monitor impacts of ocean acidification on marine ecosystems. In order to gain insight into their adaptive potential to future environmental changes, it is critical to use adequate molecular tools to delimit species and population boundaries and to assess their genetic connectivity. We developed a set of target capture probes to investigate genetic variation across their large-sized genome using a population genomics approach. Target capture is less limited by DNA amount and quality than other genome-reduced representation protocols, and has the potential for application on closely related species based on probes designed from one species. RESULTS: We generated the first draft genome of a pteropod, Limacina bulimoides, resulting in a fragmented assembly of 2.9 Gbp. Using this assembly and a transcriptome as a reference, we designed a set of 2899 genome-wide target capture probes for L. bulimoides. The set of probes includes 2812 single copy nuclear targets, the 28S rDNA sequence, ten mitochondrial genes, 35 candidate biomineralisation genes, and 41 non-coding regions. The capture reaction performed with these probes was highly efficient with 97% of the targets recovered on the focal species. A total of 137,938 single nucleotide polymorphism markers were obtained from the captured sequences across a test panel of nine individuals. The probes set was also tested on four related species: L. trochiformis, L. lesueurii, L. helicina, and Heliconoides inflatus, showing an exponential decrease in capture efficiency with increased genetic distance from the focal species. Sixty-two targets were sufficiently conserved to be recovered consistently across all five species. CONCLUSION: The target capture protocol used in this study was effective in capturing genome-wide variation in the focal species L. bulimoides, suitable for population genomic analyses, while providing insights into conserved genomic regions in related species. The present study provides new genomic resources for pteropods and supports the use of target capture-based protocols to efficiently characterise genomic variation in small non-model organisms with large genomes.

Vertical gradients in species richness and community composition across the twilight zone in the North Pacific Subtropical Gyre.

Although metazoan animals in the mesopelagic zone play critical roles in deep pelagic food webs and in the attenuation of carbon in midwaters, the diversity of these assemblages is not fully known. A metabarcoding survey of mesozooplankton diversity across the epipelagic, mesopelagic and upper bathypelagic zones (0-1500 m) in the North Pacific Subtropical Gyre revealed far higher estimates of species richness than expected given prior morphology-based studies in the region (4,024 OTUs, 10-fold increase), despite conservative bioinformatic processing. Operational taxonomic unit (OTU) richness of the full assemblage peaked at lower epipelagic-upper mesopelagic depths (100-300 m), with slight shoaling of maximal richness at night due to diel vertical migration, in contrast to expectations of a deep mesopelagic diversity maximum as reported for several plankton groups in early systematic and zoogeographic studies. Four distinct depth-stratified species assemblages were identified, with faunal transitions occurring at 100 m, 300 m and 500 m. Highest diversity occurred in the smallest zooplankton size fractions (0.2-0.5 mm), which had significantly lower % OTUs classified due to poor representation in reference databases, suggesting a deep reservoir of poorly understood diversity in the smallest metazoan animals. A diverse meroplankton assemblage also was detected (350 OTUs), including larvae of both shallow and deep living benthic species. Our results provide some of the first insights into the hidden diversity present in zooplankton assemblages in midwaters, and a molecular reappraisal of vertical gradients in species richness, depth distributions and community composition for the full zooplankton assemblage across the epipelagic, mesopelagic and upper bathypelagic zones.

Trait biogeography of marine copepods - an analysis across scales.

Functional traits, rather than taxonomic identity, determine the fitness of individuals in their environment: traits of marine organisms are therefore expected to vary across the global ocean as a function of the environment. Here, we quantify such spatial and seasonal variations based on extensive empirical data and present the first global biogeography of key traits (body size, feeding mode, relative offspring size and myelination) for pelagic copepods, the major group of marine zooplankton. We identify strong patterns with latitude, season and between ocean basins that are partially (c. 50%) explained by key environmental drivers. Body size, for example decreases with temperature, confirming the temperature-size rule, but surprisingly also with productivity, possibly driven by food-chain length and size-selective predation. Patterns unrelated to environmental predictors may originate from phylogenetic clustering. Our maps can be used as a test-bed for trait-based mechanistic models and to inspire next-generation biogeochemical models.

Size- and shape-dependent ingestion and acute toxicity of fragmented and spherical microplastics in the absence and presence of prey on two marine zooplankton.

As microplastics (MPs) are particulate pollutants, their size and shape, and the presence of prey in the media can affect their toxicity. However, the size- and shape-dependent toxicities of MPs and their prey-dependent ingestion patterns in marine zooplankton are not well understood. Thus, we investigated the ingestion and egestion patterns, and toxicity of different shapes and sizes of MPs on two marine zooplankton, Brachionus koreanus and Diaphanosoma celebensis, under different prey conditions. The ingestion assay showed that smaller MPs were ingested more frequently, regardless of their shape. However, fragmented MPs showed higher toxicity than spherical MPs of comparable size. Prey in the media reduced the uptake and toxicity of MPs in both species depending on the taxa's feeding strategy. Our findings demonstrate that the size and shape of MPs are important factors in determining toxicity and that the presence of prey should also be considered when assessing MP toxicity.

Lymnaea stagnalis and Ophryotrocha diadema as Model Organisms for Studying Genotoxicological and Physiological Effects of Benzophenone-3.

Benzophenone-3 (BP-3) is a lipophilic organic compound that occurs naturally in flower pigments. Since it adsorbs ultraviolet (UV) radiation in the UVA and UVB regions, it is one of the most common UV filters found in sunscreen and cosmetic products. We explored by in vivo micronuclei (MNi) assay the genotoxic effects of BP-3 on hemocytes from the freshwater gastropod Lymnaea stagnalis. We also studied its possible toxic effects on life-history traits: body growth in L. stagnalis and egg production of both L. stagnalis and the marine polychaete worm Ophryotrocha diadema. Adult individuals were exposed to increasing concentrations of BP-3 (0.025, 0.050, 0.100, and 0.200 mg/L) once a week for 4 weeks. In L. stagnalis, exposure to BP-3 at concentrations of both 0.2 and 0.1 mg/L produced genotoxic effects on the micronuclei frequencies, but only concentrations of 0.2 mg/L affected the NBUDs frequencies. Similarly, negative effects on body growth were observed at the concentrations of 0.2 and 0.1 mg/L and a significant reduction of egg production at 0.2 mg/L. In O. diadema, a negative correlation between egg production and increasing BP-3 concentrations was observed. Our findings suggest the need for more stringent measures to reduce the presence of BP-3 in the environment.

Tributyl phosphate can inhibit the feeding behavior of rotifers by altering the axoneme structure, neuronal coordination and energy supply required for motile cilia.

Organophosphorus flame retardants (OPFRs) are frequently detected in aquatic environments and can potentially amplify the food chain, posing a potential risk to organisms. Marine invertebrates have primitive nervous systems to regulate behavior, but how they respond to OPFRs that are potentially neurotoxic substances is unclear. This study assessed changes in the feeding behavior of rotifer Brachionus plicatilis exposed to alkyl OPFRs tributyl phosphate (TnBP) (0.376 nM, 3.76 and 22.53 µM) to elucidate the mechanism of behavioral toxicity. TnBP at 22.53 µM reduced the ingestion and filtration rates of rotifers for Chlorella vulgaris and Phaeocystis globosa in a 24-h test and altered rotifer-P. globosa population dynamics in 15-d coculture. Ciliary beat frequency was also reduced, and the expression of genes encoding the cilia axoneme was downregulated. TnBP could inhibit rotifer acetylcholinesterase activity by binding this protein and reduce the expression of the exocytotic membrane protein syntaxin-4, suggesting a disorder in nervous regulation of cilia beat. Moreover, TnBP induced abnormal shape and dysfunction of mitochondria, which caused insufficient energy required for ciliary movement. This study revealed diverse neurotoxicity mechanisms of TnBP, particularly as a potentially competing acetylcholinesterase ligand for aquatic invertebrates. Our research also provides a meaningful reference for OPFR-induced behavioral toxicity assessments.

Perspectives of species identification by MALDI-TOF MS in monitoring-Stability of proteomic fingerprints in marine epipelagic copepods.

We analysed the robustness of species identification based on proteomic composition to data processing and intraspecific variability, specificity and sensitivity of species-markers as well as discriminatory power of proteomic fingerprinting and its sensitivity to phylogenetic distance. Our analysis is based on MALDI-TOF MS (matrix-assisted laser desorption ionization time of flight mass spectrometry) data from 32 marine copepod species coming from 13 regions (North and Central Atlantic and adjacent seas). A random forest (RF) model correctly classified all specimens to the species level with only small sensitivity to data processing, demonstrating the strong robustness of the method. Compounds with high specificity showed low sensitivity, that is identification was based on complex pattern-differences rather than on presence of single markers. Proteomic distance was not consistently related to phylogenetic distance. A species-gap in proteome composition appeared at 0.7 Euclidean distance when using only specimens from the same sample. When other regions or seasons were included, intraspecific variability increased, resulting in overlaps of intra and inter-specific distance. Highest intraspecific distances (>0.7) were observed between specimens from brackish and marine habitats (i.e., salinity probably affects proteomic patterns). When testing library sensitivity of the RF model to regionality, strong misidentification was only detected between two congener pairs. Still, the choice of reference library may have an impact on identification of closely related species and should be tested before routine application. We envisage high relevance of this time- and cost-efficient method for future zooplankton monitoring as it provides not only in-depth taxonomic resolution for counted specimens but also add-on information, such as on developmental stage or environmental conditions.

Ingestion and contact with polyethylene microplastics does not cause acute toxicity on marine zooplankton.

Toxicity of polyethylene microplastics (PE-MP) of size ranges similar to their natural food to zooplanktonic organisms representative of the main taxa present in marine plankton, including rotifers, copepods, bivalves, echinoderms and fish, was evaluated. Early life stages (ELS) were prioritized as testing models in order to maximize sensitivity. Treatments included particles spiked with benzophenone-3 (BP-3), a hydrophobic organic chemical used in cosmetics with direct input in coastal areas. Despite documented ingestion of both virgin and BP-3 spiked microplastics no acute toxicity was found at loads orders of magnitude above environmentally relevant concentrations on any of the invertebrate models. In fish tests some effects, including premature or reduced hatching, were observed after 12 d exposure at 10 mg L-1 of BP-3 spiked PE-MP. The results obtained do not support environmentally relevant risk of microplastics on marine zooplankton. Similar approaches testing more hydrophobic chemicals with higher acute toxicity are needed before these conclusions could be extended to other organic pollutants common in marine ecosystems. Therefore, the replacement of these polymers in consumer products must be carefully considered.

Increased tolerance to oil exposure by the cosmopolitan marine copepod Acartia tonsa.

Oil contamination is an environmental hazard to marine ecosystems, but marine organism tolerance to oil after many generations of exposure remains poorly known. We studied the effects of transgenerational oil exposure on fitness-related traits in a cosmopolitan neritic copepod, Acartia tonsa. Copepods were exposed to an oil compound, the PAH pyrene, at concentrations of 1, 10, 100 and 100+(the saturated pyrene concentration in seawater)nM over two generations and measured survival, sex ratio, size at maturity, grazing rate and reproductive success. Exposure to the pyrene concentration of 100+nM resulted in 100% mortality before adulthood in the first generation. At the pyrene concentration of 100nM, pyrene reduced grazing rate, increased mortality, reduced the size of females and caused lower egg production and hatching success. Importantly, we found strong evidence for increased tolerance to pyrene exposure in the second generation: the reduction in size at maturity of females was less pronounced in the second generation and survival, egg production and hatching success were recovered to control levels in the second generation. The increased tolerance of copepods to oil contamination may dampen the direct ecological consequences of a coastal oil spill, but it raises the concern whether a larger fraction of oil components accumulated in survived copepods, may be transferred up the food web.

Responses of the rotifer Brachionus plicatilis to flame retardant (BDE-47) stress.

A series of short-term toxicological tests were conducted on the rotifer Brachionus plicatilis to assess the toxicity of the flame retardant 2,2',4,4'-tetrabrominated biphenyl ether (BDE-47). BDE-47 increased mortality, morphological damage, and altered population dynamics and fecundity of rotifer. Antioxidant enzymes were differentially changed to maintain the balance between antioxidant and pro-oxidant activity. However, with increases in the concentration of BDE-47, the metabolic and antioxidant activity decreased. Moreover, the reactive oxygen species (ROS) and malondialdehyde contents increased and the ratio between glutathione and glutathione-SH decreased, indicating oxidative stress. The addition of the ROS-inhibitor N-acetylcysteine alleviated the degree of damage and stimulated the activity of xenobiotic-metabolizing and antioxidant system, which suggested that ROS were the most important loop in the stress response.

Monitoring of genotoxicity in marine zooplankton induced by toxic metals in Ennore estuary, Southeast coast of India.

The present study provides preliminary in-situ data on genetic integrity of marine zooplankton. Paracalanus parvus, Oithona rigida and Euterpina acutifrons were collected during four different seasons (summer, pre-monsoon, monsoon and post-monsoon) from 2011 to 2012 in Ennore and Kovalum estuaries. DNA damage levels in different zooplankton were analyzed by comet assay and were correlated with different environmental stressors. Spatial and temporal variations in DNA damage was observed in all the species. Zooplankton from Ennore estuary showed significantly lower genetic integrity. Particulate, sediment, and zooplankton fractions of Pb, Ni, Cu, Cr and Co were associated with high DNA damage during the period of lowest pH, salinity and dissolved oxygen. Zn and Cd showed lower genotoxic impact than the other metals. Feeding modes strongly influenced the genetic integrity in the zooplankton species studied. These results support the use of comet assay as a tool in effectively monitoring genotoxicity in marine plankton communities.

A new species of Caligus (Copepoda, Siphonostomatoida) from the plankton of the Caribbean coast of Venezuela with a key to species.

During a survey of the zooplankton community of Bahía Amuay, Venezuelan Caribbean, specimens of an undescribed species of Caligus Müller were collected. It resembles Caligus xystercus Cressey and Caligus ocyurus Cressey, both known only from the Caribbean Sea. The new species can be distinguished from these and other congeners by a combination of characters including the armature of legs 1 and 4, but mainly by its unique female genital complex. This is the first species of Caligus described from Venezuela. The species is described in full and a key to the species of the genus recorded in Venezuela is provided.

Anfípodos hiperídeos (Crustacea: Peracarida) del Parque Nacional Isla del Coco, Costa Rica, Pacífico Tropical Oriental / Hyperiid amphipods (Crustacea: Peracarida) of the Parque Nacional Isla del Coco, Costa Rica, Eastern Tropical Pacific

Hyperiid amphipods are one of the most frequently encountered pelagic crustaceans and among the most diverse marine zooplankters. To determine the species composition of the hyperiid amphipods dwelling in the waters around Isla del Coco National Park, Pacific Costa Rica, we analyzad 12 zooplankton samples, collected by vertical and horizontals tows with plankton net with mesh sizes of 200 and 500 microns and 49cm mouth diameter. We recorded a total of 22 species belonging to 17 genera and 12 families. A faunistic list of this group is provided together with data on their taxonomy and their distribution both in the surveyed area and in general. Most of the species recorded in this zone have been reported in previous surveys in the Eastern Tropical Pacific region and particularly in oceanic waters of Costa Rica. We found eight species representing new records for Costa Rican waters, thus increasing by 26% (to 38) the number of hyperiid species known from Costa Rica. The most frequent species were Lestrigonus shoemakeri, L. bengalensis, Hyperiodes sibaginis, and Phronimopsis spinifera. We expect that additional samplings both from surface and deep waters will expand the knowledge of the diversity of the group in this important protected area.

Los anfípodos hiperídeos son uno de los grupos de crustáceos pelágicos más frecuentemente encontrados y están entre los más diversos del zooplancton marino. Para determinar la composición de especies de anfípodos hipéridos que habitan las aguas alrededor del Parque Nacional Isla del Coco, Costa Rica, se analizaron 12 muestras de zooplancton. Estas fueron recolectadas mediante arrastres verticales y horizontales con una red de plancton con mallas de 200 y 500 micras y 49cm de diámetro en la boca. Se encontró un total de 22 especies pertenecientes a 17 géneros y 12 familias. Se presenta el listado faunístico de este grupo junto con datos acerca de su taxonomía, su distribución en el área de estudio y su distribución general. La mayor parte de las especies registradas en esta zona han sido reportadas en estudios previos referentes a la región del Pacífico Tropical Oriental y en particular en aguas oceánicas de Costa Rica. Encontramos ocho especies que representan nuevos registros para aguas del Pacífico costarricense, lo que incrementa en un 26% (a 38) el número de especies de hipéridos conocidos en Costa Rica. Las especies más frecuentes fueron Lestrigonus shoemakeri, L. bengalensis, Hyperioides sibaginis y Phronimosis spinifera. Se espera que muestreos adicionales tanto de aguas superficiales como profundas expandan el conocimiento de la diversidad del grupo en esta área protegida.

Algunos poliquetos holoplanctónicos (Annelida: Polychaeta) del Parque Nacional Isla del Coco, Costa Rica / Some holoplanktonic polychaetes (Annelida: Polychaeta) from the Parque Nacional Isla del Coco, Costa Rica

The holoplanktonic polychaetes have not been surveyed in the oceanic waters adjacent to Isla del Coco. These pelagic forms are studied based on the analysis of zooplankton samples collected in the area. Samples were obtained both at night and daytime by standard plankton nets (0.2-0.5 mm meshes, 0.49 m mouth diameter) hauled horizontally and vertically off the oceanic island Isla del Coco, Costa Rica in the Eastern Tropical Pacific. Pelagic polychaetes were collected in one of the night samples and were taxonomically analyzed. The material obtained includes representatives of six species and five families: Alciopidae, Lopadorrhynchidae, Tomopteridae, Polynoidae, and Typhloscolecidae. Brief diagnoses, synonymies, comparative morphological comments, taxonomic illustrations, and data on the distribution of the species collected in the plankton of Isla del Coco are provided. The record of Drieschia pellucida Moore is the first of the species in the Eastern Tropical Pacific; our specimen shows some differences with respect to the original description. The rest of the species have been recorded previously in waters of the Eastern Tropical Pacific, but are the first records of this important protected area.

Los poliquetos holoplanctónicos no han sido estudiados en las aguas oceánicas adyacentes al Parque Isla del Coco. Se estudiaron estas formas pelágicas a partir del análisis de muestras de zooplancton recolectadas en esta área protegida. Las muestras fueron obtenidas mediante redes de plancton estándar (0.2-0.5mm de malla, 0.49m de diámetro de boca) en arrastres horizontales y verticales en la isla oceánica Isla del Coco, Costa Rica, en el Pacífico Tropical Oriental. Los poliquetos pelágicos de esta zona fueron analizados taxonómicamente. El material obtenido incluye representantes de seis especies y cinco familias: Alciopidae, Lopadorhynchidae, Tomopteridae, Polynoidae y Typhloscolecidae. Se presentan diagnosis breves, sino- nimias, análisis morfológicos comparativos, ilustraciones taxonómicas y la distribución conocida de las especies recolectadas en el plancton de Isla del Coco. El registro de Drieschia pellucida Moore es el primero en el Pacífico Tropical Oriental; nuestro espécimen muestra algunas diferencias respecto a la descripción original. El resto de las especies han sido encontradas previamente en aguas del Pacífico Tropical Oriental y en el Domo de Costa Rica, pero son los primeros registros para esta área protegida.

Medusas (Cnidaria: Hydrozoa) de una zona de afloramiento costero, Bahía Culebra, Pacífico, Costa Rica / Medusae (Cnidaria: Hydrozoa) from a coastal upwelling zone, Culebra Bay, Pacific, Costa Rica

The hydromedusae have an important role in marine trophic webs due to their predatory feeding habits. This is the first study of this group of gelatinous marine zooplankton in a coastal upwelling area of Central America. The composition and abundance variability of hydromedusae were studied during six months in 1999 at four stations in Culebra Bay, Gulf of Papagayo, Pacific coast of Costa Rica (10º37’ N-85º40’ W). A total of 53 species were identified, of which 26 are new records for Costa Rica, 21 are new records for Central America, and eight are new records for the Eastern Tropical Pacific. The more abundant species (more than 30% of the total abundance) were Liriope tetraphylla, Solmundella bitentaculata and Aglaura hemistoma. Six species occurred throughout the sampling period, 10 were present only during the dry season (December-April), and 17 were so during the rainy season (May-November). Significant differences of medusan abundances were found between seasons (dry vs. rainy). Maximum abundance (2.1±4.3ind./m³) was recorded when upwelled deeper water influenced the Bay, as indicated by local higher oxygen concentrations and lower water temperatures. The relatively high species richness of medusae found in Culebra Bay is probably related to factors like the pristine condition of the Bay, the arrival of oceanic species transported by the Equatorial Counter Current (ECC), the eastward shoaling of the Costa Rica Dome, and local currents. Illustrations of the 15 more important species are included to facilitate their identification and foster future work in the region.

Las hidromedusas tienen un papel importante en redes tróficas marinas debido a sus hábitos alimenticios depredadores. Este es el primer estudio de este grupo del zooplancton gelatinoso en un area de afloramiento costero en América Central. Durante seis meses de 1999, se estudió la abundancia de hidromedusas en cuatro estaciones en Bahía Culebra, Golfo de Papagayo, costa Pacífica de Costa Rica (10º 37’N-85º40’W). Se identificó un total de 53 especies de las que 26 son registros nuevos para Costa Rica, 21 son registros nuevos para América Central y 8 son nuevos registros para el Pacífico Oriental Tropical. Las especies más abundantes durante el estudio (con más de 30% de la abundancia total) fueron Liriope tetraphylla, Solmundella bitentaculata y Aglaura hemistoma. Seis especies se presentaron en todos los muestreos, 10 especies se presentaron únicamente durante la época seca y 17 se presentaron únicamente durante la época lluviosa. Se mostraron diferencias significativas entre las épocas lluviosa y seca. La máxima abundancia promedio de hidromedusas (2.1±4.3 ind./m³) fue encontrada durante las fechas que se espera el afloramiento costero, indicado por alta concentración de oxígeno y baja temperatura. La rica composición de especies encontrada en Bahía Culebra puede ser el resultado de varios factores, incluyendo la condición prístina de la bahía, el transporte de especies por la Contra Corriente Nor-Ecuatorial (NECC) y los aportes de origen terrestre. Se incluyen ilustraciones de las 15 especies más importantes para facilitar su identificación y promover estudios futuros en la región.