Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

During the first cruise leg with the RY Victor Hensen to tile Pacific coast of Costa Rica in December 1993 (end of the rainy season) the custacean fauna found in the demersal collections revealed an unexpected species richness and biomass. The Crustacea collections were analyzed qualitatively and quantitatively during the fourth leg (February 1994, dry season) in the three study areas Golfo Dulce (GD). Bahía Coronado in the Sierpe-Térraba-estuary (ST) and Golfo de Nicoya (GN). Qualitative data were available (or comparison from the first leg in december 1993. A total of 24 beamtrawl and ten ottertrawl sample collections were done on an area of 860.000 m2 yielding a total of 119 species with a biomass of 37.8 kg (10275 specimens). Despite the smaller area covered by the beamtrawl, it collected a higher num­ber of species and more biomass than the ottertrawl due to the smaller mesh size (0.8 cm). Judging from the shape of the species-per-area-curves, the crustacean fauna appeared representatively sampled for the study area. As compared with the GN (biomass 0.36 g ± 0.26, SR = 97) and the ST (0.41 g ± 0,27, SR = 59) and according to the results of the log-series-plots constructed from the abundance data. the GD seems to be a depauperated area with significantly lower biomass (0.05 g ± 0,07) and species richness (45 sp.). No crustaceans were found in the center of the deep basin of the GD but parts of the interior gulf with adjacent mangrove areas seem to be important as nursery area for some commer­cially important penacid shrimp species. The ST-estuary revealed the highest mean species number per station in the whole study area, but the GN had the highest total number of species. Biomass seems to be regularly distributed and not depth-depending within the GN. while species abundance varies clearly, confirming previous results. In contrast. abun­dance and biomass correlated well in the ST. Based on the results of the multivariate analysis, seven station groups of particular species assemblages can be distinguished in the study areas. Despite a high variability between stations in abundance and biomass, the following four areas of characteristic species assemblages can be identified which are also confirmed by an independent study on demensal fishes: (I) the interior part of the GN, characterized by juvenile shrimps (Sicyonia disdorsalis, Trachypenaus fuscina), several patchily distributed anomurans, brachyurans and other predator species like portunids (especially Portunus asper) and pre-adult stomatopods (Squilla spp.); (2) the exterior part of the GN with high amounts of caridean (Pantomus affinis, Plesionika spp.) and penaeid shrimps (Sicyonia picta, Solenocera mutator), the highly abundant Iliacantha hancocki and some specimens of the stomatopod Hemisquilla stylifera and the deep water ponunid Portunus iridiscens; (3) a transition zone between 60 and 120 m water depth with a heterogeneous faunal composition, located in the ST and cast of Isla Tortugas in the GN. and (4) the oxygen-depleted shelf edge area, dominated by the galatheid Pleuroncodes monodon. Mass occurrence of this species takes place off the GO and to a lesser extent off the ST-estuary, associated with high numbers of Solenocero spp. There seems to be a general trend of species groupings along abiotic gradients (depth, temperature, oxygen saturation) interrupted by small-scale variations in habitat type, current regime, food availability and other factors not identified in this study. Neither total abundance and biomass nor biotic summary parameters like diversity, dominance or species richness correlated well with the abiot­ic factors measured during this survey.

A list of 54 copepod species (Crustacea) in 23 families is presented for the Pacific coast of Costa Rica. Identifications are from zooplankton samples of the Victor Hensen Expedition during December 1993 and February 1994. Samples were taken with a Bongo net (0,60 m net opening. 2.50 m net length) with 200 μm mesh size. Oblique hauls were done from the surface to the ground at a towing speed of aprox. 1 knot. 37 species (68.5%) we re found in the Gulf of Nicoya. 36 in Golfo Dulce (66.6%) and 17 (31.4%) species were common to both gulfs. while only twelve species (22.2%) were found in Coronado Bay. Four species (7.4%) were distributed along the coast and were common to the three regions: Paracalanus parvus, Euchaeta sp., Oithona plumifera and O. similis. Eleven species of calanoids found normally in the Costa Rica Dome show the influence of typical oceanic waters principally at the mouth of Gulf of Nicoya. Differences were observed in the composition and presence of the copepod species when the inner and outer (upper and lower) pans of both gulfs were compared. Gulf of Nicoya was dominated in its upper pan by typical neritic estuarine species like Acartia lilljenborgii. Paracalanus parvus and Hemicyciclops thalassius as well as species of Pseudodiaplomus. On the other hand a more oceanic composition of copepods was observed in the lower part of the gulf. BOth small species, like Oncaea venusta, as well as larger species, such as Pleuromamma rubusta, Eucalanus attenustus, E. elongatus and Rhinalanus nasatus, were typical of these waters. Oithona plumifera and O. similis were found in the lower part too; and both species are typical from oceanic water. Coronado Bay was characterized by the presence of typical oceanic species like Neocalanus gracilis, Euchaeta longicornis, Eucalanus attenuatus and Haloptilus ornatus with more transitional species like Clausocalanus pergens and C. furcatus near the coast. In the Golfo Dulce differences in copepod composition were also observed, but the separation of the species was not so evident. Outer stations were represented by oceanic species like Paracalanus aculeatus, Pleuromamma gracilis, Lucicutia ovalis, Candancia catula, Euchaeta wolfendendeni and Oncaea mediterranea, while the inner station, located at the upper pan of the Gulf, was more characterized by a mixed copepod group. with both neritic species like Pseudodiaptomus wrighti, Acartia danae, A. clausi, Canthoralanus pauper as well as oceanic species like ScolicitricelIa marginata, Saphirina nicramaculata or Oncaea conifera. Two species of Coryceaus, C. flaccus and C. speciosus, were identifed in the outer stations of Golfo Dulce. while C. brehmi was found in inner stations of Gulf of Nicoya. The majority of copepods found are typical of the east Pacific. This paper constitutes an additional work about the copepods in the Gulf of Nicoya and the first report of copepod species for Coronado Bay and Golfo Dulce.

This study is based on a subset of plankton samples obtained during an expedition of the German RV Victor Hensen to the Pacific coast of Costa Rica in 1993/94. It aims at the identification of the main plankton taxa for a gene­ral description and comparison of the plankton communities of the gulf systems Golfo de Nicoya (GN) and Golfo Dulce (GO) and tile analysis of biomass spectra at inshore and offshore stations at the end of the rainy season and du­ring the dry season. Inshore plankton biomass was significantly higher in GN than GO and exceeded offshore biomass several times, while in the GO area the reverse was found. In the rainy season, inshore biomass spectra of GN and GO were discontinuous with biomass concentrations at small sizes (around O.06mg) suggesting little developed communi­ties. with highest production and energy use occurring in the small organisms. From the rainy to the dry season inshore species richness increased in both gulf systems and a shift was observed towards the larger size groups resulting in more continuous biomass spectra. In GN, bivalve larvae, foraminifers, ostracods, mysids and nauplii increase heavily in abundance and some gelatinous specimens occur. In GO. gelatinous zooplankton appears in enormous abundance and dominate the community biomass, followed by large chaetognaths and ostracods. In GO. inshore plankton has neritic and oceanic elements and differs less from the offshore plankton, whereas in GN, inshore plankton is largely neritic. The high abundance of fish eggs and invertebrate larvae suggest that this area is an important spawning ground. While in the rainy season inshore biomass was about 15 limes higher in GN compared to GO, this difference was reduced to 3-4 times in the dry season due to the appearance of the large predators mentioned above. The changes from the rainy to the dry season at the offshore stations of both gulf systems are less pronounced in terms of total bio­mass, shape of the biomass spectra and taxonomic composition of the community. The differences - relatively continu­ous biomass spectra with an increasing slope and a high total biomass in GD versus flat and sooner spectra due to the absence of large chaetognaths and medusa in the GN - suggest that conditions in the former area a!low for a better development of a trophodinamically tightly Structured plankton community.

The chaetognath species guild was analyzed from samples collected during the cruise of the German RV Victor Hensen to the Pacific coast of Costa Rica in December 1993 and February 1994. finding the following ten species of the genera Sagitta and Krohnitta: S.enflata, S. hexaplera, S. pacifica, S. neglecta, S. regularis, S. bedoti, S. friderici, S. popovicii, S. pulchra and K. pacifica. Because of their distributional patterns in the study area these species were ascribed to the following ecological groups: neritic, semi-neritic and oceanic. A strong gradient in species richness from offshore to inshore waters (810 one respectively) was found in both gulf systems. In shore chaetognaths were dominated by juveniles and adults of S. friderici in Golfo de Nicoya and by S. popovicii in Golfo Dulce. Biomass spectra were more continuous and of wider range in the Golfo Dulce area showing a dominance of larger chaetognaths. suggesting a more general developed pelagic system in Golfo Dulce, where larger chaetognaths might structure the plankton community by strong grazing pressure from above.

During two cruise legs with the RV Victor Hensen (December 1993, February 1994), the demersal fish assemblages of the Golfo de Nicoya (GN). Bahia Coronado-Sierpe Terraba (ST) and Golfo Dulce (GD) areas were assessed from nearshore (-20 m) to shelf edge (-200 m) waters. 44 Beam- and 29 otter trawl collections were made on an area of 2 119 405 m2, yielding a total of 242 species of fish. Despite the lower number of samples taken, more species were collected by the otter trawl (189 compared to 160), due to a wider area swept. As revealed by the species-area curve and a lognormal - curve constricted from the pooled (log) abundance data, the fish assemblage appeared as well sampled and a theoretical species richness (SR) of - 306 was estimated for the whole area. Mean species num­ber per collection and mean biomass per area were much lower in the GD - area (9.3 species. O.36g /m2) compared to the ST (15.4, 0.81g/m2) and GN (17.3.0.74 g/m2) areas. indicating a depauperate fish assemblage in the former. Lowest species numbers and biomass were found in the central deep pan of GO with increasing values towards the still area at the opening of the gulf and towards the shallow stations above the thermocline. Average biomass was an order of magnitude higher in the interior pan of GN compared 10 the other areas with values up 10 18.1 g/m2. Based on results of a multivariate analysis of the col1ections, the GN area can be divided into (I) an interior shallow area above the thermocline (<50 m) characterized by scianids, sea catfishes, stingrays, flatfishes, sea robins, (2) an outer patt (>100 m) characterized by cods, scorpionfishes, gobies, cutlassfishes, serranids, anglerfishes and flatfishes and (3) a transition zone of the central and lateral patts with a mixed species assemblage with carangids. pufferfish. snappers. several flatfish species and the lizardfish as common elements. Characteristic for the deep basin of GD were small species of the genera Cynoscion and Porichthys. These occurred in low densities. suggesting a reduced canying capacity of this deep basin for fish biomass in terms of food and oxygen. Species occurring at the shallow stations of GD are also found at a similar depth in the ocher areas. but many species are missing. namely ariids and many scianids found in the GN area. The species assemblage of the ST area resembles that of GN. Ariids. however. are missing here too. Biotic station parameters like species richness. biomass. abundance and production were not significantly correlat­ed with abiotic parameters (temperature. oxygen. nutrients) suggesting that other habitat factors not evaluated in this study like habitat heterogeneity, distance to the open ocean. current regime and food availability probably are impor­tant factors for the structure of the fish assemblage.

Golfo Dulce is a deep tropical estuary whose ecosystem dynamics are poorly understood. In order to evaluate biomass and energy now distributions, productivity potential. and to obtain guidelines for conservation management, a steady - state model of 20 compartments (excluding detritus) was constructed using the: ECOPATH II software. Total system biomass (10.4 t/km2) and total energy throughput (sum of all flows, T = 1405 t/km2/year) of Golfo Dulce are small compared to other modeled coastal ecosystems. The mayor pan of the energy throughput is achieved from primarily pelagic trophic levels I to II (52%) plus 11 to III (41 %). The pelagic fish biomass consumed with in the system by top predators (about 1133t) exceeds twice The demersal fish biomass consumed (5021). Artesanal fishery primarily operates on the top trophic levels of the benthic domain and has a very low gross efficiency (catch/ primary production = 0.06%). A nearly balanced production/repiration ratio (P/R = 1.09) and a high mean tranfer efficiency (15%) suggest that the system is near maturity. Contradictory seem the low Ascendency (A= 32.2%) and high development Capacity (OC = 61.8%) values indicative of a relatively undeveloped system of little internal stability. This contradiction might be explained through the fact that much of the detrital matter produced within the euphotic zone is sedimented away and does not - like in other coastal systems - reenter the food web. Thus, whereas the pelagial represents a tightly coupled rather mature (sub) system, the Golfo Dulce as a whole lacks this degree of maturity due to a very inefficient benthic pelagic coupling, which results from its fjord-like topography. The model reveals that Golfo Dulce acts differently from most tropical coastal ecosystems: it is dominated by biomass and energy flow within the pelagic domain and ruther resembles an open ocean system than an estuarine one. Due to its low benthic biomass and low overall productivity, there seems to be no potential for further development of the demersal/semi-demersal fishery inside the gulf. An increase of the pelagic fishing pressure would seriously threaten the populations of resident predators such as dolphins, sharks and large bird species. which have considerable conservation and ecotourism values. Future ecosystem research in Golfo Dulce should focus on the pelagic part of the gulf (microbial loop, plankton, and nekton), on the small benthos. as well as on transfer processes within the pelagic: domain, between the pelagial and the brnthos, and at the river/gulf and gulf/ocean interfaces.

Ichthyoplakton surveys were conducted in December (rainy season), 1993 and February (dry season), 1994, during the RV Victor Hensen German-Costa Rican Expedition to the Gulf of Nicoya and Golfo Dulce. Costa Rica. Samples from the inner, central, and outer areas of each gulf were collected in oblique tows with a bongo net of 0.6 m mouth diameter, 2.5 m long and 1000-μm mesh. A total of 416 fish larvae of 22 families; were sorted out of 14 samples. Stations of both the maximum (II) and the minimum (I) family richness were located in Golfo Dulce. Mean total larval abundances were 124.9 and 197.2 individuals 10 m-2 for the Gulf of Nicoya and Golfo Dulce, respectively, while mean larval densities ranged from 95.3 larvae 10 m-2 in December to 236.7 larvae 10 m-2 in February. However, no statistical differences between gulfs or seasons were detected. due to the high within-group variability. Cluster Analysis, Multi-Dimensional Scaling (MDS), and non-parametric tests showed two well-defined major groups: (I) the Gulf of Nicoya neritic assemblage, represented by Engraulids, Sciaenids, and Gobiids (inner and central stations), and (2) the oceanic assemblage, dominated by Myctophids, Bregmacerotids, Ophiidids, and Trichiurids (outer stations off the Gulf of Nicoya and Golfo Dulce). A third, although less defined group, was an Ophichthid-dominated assemblage (typical in areas nearby coral or rocky reefs). These assemblages closely resemble the clusters based upon adult fish data of the beamtrawl catches of the same cruise. This publication is the first to report on the ichthyoplankton community of Golfo Dulce.

A list is presented of 242 species of fishes taken in the Golfo de Nicoya, Golfo Dulce and on the Pacific continental shelf of Costa Rica. The specimens were collected using dredges and bottom trawls during December 1993 and February 1994. The Golfo Dulce revealed the lowest diversity with only 75 species represented; 118 species were collected in the Golfo de Nicoya and 129 species in offshore waters. It is presumed that low fish diversity in Golfo Dulce is due to the deep, unproductive waters in that embayment. The checklist includes presence-absence data for each locality.

In this work five species of molluscs (Gastropoda) are reported for the first time from Costa Rica. The specimens were collected during the R.V. Victor Hensen Cruises. In the three study areas, beamtrawl and ottertrawl hauls were conducted along a depth gradient from about 20 m to 200 m. (Wolff and Vargas 1994). All specimens were preserved in 10% formalin and identified using Keen (1971). Notes about synonyms, size and geographic distribution are provided for each species based on Skoglund (1992).

A coral disease characterized by a novel pattern of rapid tissue destruction first appeared on reefs of the middle Florida Keys in lune 1995. Between lune and October 1995 the disease infected 17 species of scleractinian corals and the hydrocoral Millepora alcicornis. Localized populations of Dichocoenia stokesi, the species most affect­ed, revealed up to 38% mortality. Many colonies exhibited complete tissue loss within days as the disease moved across colonies at rates of up to 2 cm per 24 hr. Typically tissue loss was initiated at the base of the colony and moved upward. At times disease progression halted and colonies retained partial tissue resembling a cap on the top of an otherwise denuded colony. Laboratory cultures of samples from the disease line revealed a dominant bacterium that, when isolated and characterized using genetic and metabolic techniques, most closely matched the genus Sphingomonas. Pure laboratory cultures of the bacterium produced disease in freshly collected coral colonies incu­bated in laboratory aquaria. The disease that we call plague type II appeared on different reefs of sou Florida and the Florida Keys in 1996 and 1997. While coral mortality associated with each of the three outbreaks was regionally confined and did no! recur in subsequent years on the same reefs, the high mortality rates distinguish this disease as one of the most serious yet documented.