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

Benthic macroinvenebrate community structure was studied with respect to stream habitat type in two lowland tropical streams. Three reaches along the Carbón river and two within tile Gandoca stream were chosen as study sites in Talamanca. Costa Rica. Macroinvenebrates were collected from four habitat types: leaf packs in rif­fles, cobble in rimes, areas of sand in pools, and areas of gravel in pools. Communities were dominated by in sec ts in the orders Ephemeroptera (Thraulodes, Baetis?. Diptera (Chironomidae. (Hydroptilidae, Glossomatidae, Hydroptilidae, Calamoceratidae), and Odonata inseci macroinvertcbrates (Progomphus. Hetarina). Non insect macroinvertebrates were dominated by shrimps (Macrobrachium) and snails (Gastrupoda). Functional feed­ing group composition was dominated by collector -gatherers. In most reaches, both habila1 types in riffles sup­ported higher macroinvertebrate abundance and biomass than did habitats in pools. Leaf packs in riffles represent an important habitat that is present year-round in these aseasonal tropical systems. Community composition and diversity were similar to that reported for other areas of Central America.

The concentrations and in-tissue distributions of six metals, were determined in sea-cucumbers Holofhu­ria (Halodeima) mexicana Ludwig 1875 from the Costa Rican Caribbean sea, by the atomle absorption technique. The samples were taken over a period of 16 months between October 1987 and December 1989, with sizes ranging between 17 and 25 cm long and weights from 280 to 600 g. The metal concentration ranges (mg kg", dry weight), were Cd 0.1-2.5; Pb 0.2-26; Mn 4.1-46; Cu 1.3-69; Zn 14-174; Fe 20-1044. and Ihe respiratory tree was the structure that showed in general the higher levels of metals, except for Cu and Pb which were higher in the muscles and the body wall, respectively. This paper constitutes an important data base for future comparisons dealing with ac­tivities involving coastal impact since there is no previous information about trace metal content in similar species from this region of the Caribbean.

Primary productivity was measured in the estuary Estero Morales during 15 months (1990-199 I). Water column primary productivity was determined using the dissolved oxygen method 31 two different depths (1=50% and 1=10%) at each research site and during two consecutive days of sampling . Rosettes were incubated for five hours with three clear bottles and two dark bottles. The Winkler method was used to determine dissolved oxygen. Primary productivity was also measured with lower sampling frequency at the Cortezas Islands to obtain a point of comparison. These sites are all located in the Gulf of Nicoya, Costa Rica (10°N, 85°W). Water column net primary productivity in Estero Morales presented average values from 1.20 ± 0.70 g C/m² d (around 450g C/m² year). Values obtained from Islas Cortezas were around 1.69 gC I m² d. There was a significant difference between the dry and rainy seasons with respect to net primary productivity (z=2.196, p<0.03). Another significant difference was determined between the depths 1=50% and 1=10% in terms of net primary productivity (z=2,51, p<0.006). The values obtained for primary productivity establish Nicoya Gulf as one of the most productive estuarics in the world. A follow-up study is recommended for this area, consisting of simultaneous sampling at different points of the Gulf of Nicoya. These samples should be taken at a minimum of five different incubation depths for each sample in order to obtain more detailed information in calculating productivity by layers in water column. It is also recommended that frequency of sampling be increased for greater assurance that results are not produced by the distribution of patches of phytoplankton.

Sediments and the marine current system at the Gandoca-Manzanilio National Wildlife Refuge. Cari­bbean coast of Costa Rica, define two sedimentary environments. One between Punta Uva and Manzanillo. where sediments were derived from the coral reefs and local geological fonnations. The Other lies between Punta Mona and Rio Sixaola. where sediments arrive primarily from outside tile an:a. fine-grained sediments were collected off rivers and creeks mouths. and adjacent beaches. The highest percentage of carbonates (60 to 80 %) was found off Punta Uva, and consisted mainly of mollusk, algal and coral fragments, and Foraminifera. Magnetite found in large quantities off Manzanillo, and also observed on the beach. was derived locally from the Rio Banano Formation. Clay and silt were found in high concentrations from Punta Mona to Rio Sixaola. Other minerals. pyroxene and hy­robiotile, probably originated from the erosion of intrusive rock s cropping out in the central section of the Tala­manea Range. The sediment plume of Rio Sixaola extends several kilometers off shore, flowing northwest and af­fecting coral reefs off Punta Mona. Other an:as of the Refuge an: not exposed to high concentrations of terrigenous sediments. However, as a result of deforestation, new constructions and removal of riparian and coastal forests, more coral reefs of the Refuge will be affected by sediments.

Southern shore of Punta Morales (10° 03' N, 84c 58' W), Gulf of Nicoya, beneath rocks, in­tertidal, August I. 1996. Collector: Harlan K. Dean, four specimens (UCR-44-0 I). Islas Cor­tezas (10° 04 ' N, 840 58' W), Gulf of Nicoya, beneath rocks. intertidal, August 5, 1996. Co­llectors: Harlan K. Dean and Jose A. Vargas, two specimens (MCZ collection).

Based on partly worked up material from three brief collecting excursions to the peninsular shore of Golfo Dulce, 252 species of shelled gastropods, mostly prosobranchs and pyramidellids, have been identified. This being the first report on intertidal and shallow water gastropods from the gulf, the list may be taken as a preliminary check list of this fauna clement from Golfo Dulce. Only partly sorted material from two additional trips to the gulf contains at least 100 additional species not yet identified.

A new species of Urotrygon is described from the Pacific coast  of Costa Rica and Nicaragua. Uritrygon cimar is a large species reaching at least 382 mmm total length and is  recogized by its dense dorsal covering of pungent denticles and dark spotted coloration. It is found in tide pools and to a depth of 85 m and is usually collected in waters shallowers that 10m.

The Pantanal wetlands represent one of the largest flood plains in the World, with extreme climatic variations between dry and wet seasons. The area shelters a high diversity of habitats, representing the main formations found in this sub-region: grasslands, savannah, forested savannah, riparian forests, bays and salines, and Negro river itself. This habitat variability determines the structure and dynamics of the bird community, because most species are closely related to specific habitats. For this, we studied the abundance of bird species from 2001 to 2004 in a Pantanal area of Fazenda Rio Negro, Aquidauana, Brazil. The abundance was compared among those four consecutive years, seasons (dry and wet), time of the day (morning and afternoon), and also between seven different habitats, in order to determine the variation in distribution patterns and habitats used by birds. For this, we used the linear transect method in each of the seven habitats, and recorded bird abundances to obtain richness. The richness registered in the mosaic of habitats was of 201 species for the savannah, 87 in forested savannah, 116 in the riparian forest, 75 in grasslands, 120 in bays, 92 in the salines and 64 in the Negro river, accounting for 348 species in the Pantanal of Rio Negro. Overall, 98 species of migratory birds were registered. The results highlighted some important issues regarding the total abundance of birds in Nhecolândia: Psittacidae was the most abundant family in the region, with prominence in all environments. Recurvirostridae, a monospecific family, showed expressive abundance due to the dominance of Himantopus mexicanus in the salinas, followed by Ardeidae, Anatidae and Cracidae. Other families with high abundance were Tyrannidae, Columbidae, Thraupidae and Emberizidae, all in predominantly terrestrial environments. Moreover: a) The highest number of specimens was recorded in the morning period and in the dry season, regardless of the habitat; b) there were no differences in abundance in the same habitat along the years, but the abundance was different among habitats. In general, the results indicated that there is a relatively stable bird population in each habitat along the annual cycle, but there were differences in abundance among habitats. Thus, additional studies on food availability in dry and wet seasons should be better explored in the future, either in this region or in other Pantanal regions. This fact could better explain the seasonal dynamics of the richness and abundance of birds in the Pantanal area in general.

The increased degradation of natural habitats has strengthened the need to know and assess biodiversity patterns. Particularly, the study of the araneofauna in the North of Argentina is scarce in ecoregions with priority interests of conservation. Generally, spiders are used as indicators to compare biodiversity patterns, and here we tested whether the spider family-level can act as a substitute of the species-level in biodiversity rapid assessments. For this, we analyzed the alpha and beta diversity of the epigeal spider communities in three separate sites of different ecoregions of Salta province (Chaco Serrano, Monte de Sierras and Bolsones, and Puna), during the fall, winter, spring and summer of 2005-2007. In each site, 10 pitfall traps, located along a linear transect and 10 meters apart, were placed for seven days per season of continuous activity. Samples were obtained, taken to the laboratory and identified. A total of 886 spiders were collected from 100 species/morphospecies of 19 families. The completeness of the inventory obtained for each ecoregion surpassed 70 %. The Chaco ecoregion (S = 56, N = 495) reported the highest species richness and abundance compared to Monte (S = 44, N = 262) and Puna (S = 23, N = 129). Alpha and beta diversity showed that ecoregional spider communities were different, sharing between them very few species (0.7 %). The Chaco reported a high dissimilarity of its assemblage with respect to the other ecoregions. The colder seasons (autumn and winter) proved to be important in assessing the diversity of spiders in these ecoregions, contributing to regional diversity in conjunction with the diversity of warm seasons (spring and summer). Four guilds were reported (ground hunters, specialists, other hunters and ambush hunters), but the latter was absent in Monte, and the specialists dominated in Chaco. Zodariidae was dominant in Chaco Serrano, where Leprolochus birabeni is an indicator of native environments. On the other hand, Lycosidae, Philodromidae, Anyphaenidae and Oonopidae were important for Monte and Puna. This way, the use of pitfall traps in all seasons of the year, and the recognition of spider families for epigeal fauna, was very useful for biodiversity rapid assessments in this area. Like the species-level, the taxonomic family-level evidenced changes in alpha and beta diversity. This allowed the inclusion of this taxonomic group for future biodiversity monitoring studies for conservation plans in these ecoregions.

Worldwide big cats are at risk of extinction, and anthropogenic factors and natural habitat disturbances represent the biggest threats for their survival. It is essential to know the natural resources use by these predators and the way these big felids adapt to changes. It is unknown how the puma (Puma concolor) selects and uses resources, and what environmental factors determine its presence and how this species is affected by natural disturbances in Mexican tropical forests. This study was performed in the El Eden ecological reserve and surroundings, in the North of Quintana Roo, Mexico, an area dominated by tropical semideciduous (medium forest) and secondary forest (acahual). Camera samplings were carried out during 2008, and from 2010 to 2012. Habitat variables, activity patterns and species associations were also spatially and temporally analyzed using a chi-squared test and overlapping coefficients. General Linear Models (GLM) were used in order to determine which variables influence the presence of cougars in the study area. Cougars used vegetation and paths in different proportions as the availability of these resources. The years with more changes (P < 0.05) were 2008 and 2011. This predator was active throughout the day, but changed its activity patterns over the years. The cougar was spatio-temporally associated with six mammals and two big terrestrial birds: Pecari tajacu (∆ = 0.52), Meleagris ocellata (∆ = 0.55), Crax rubra (∆ = 0.58), Didelphis sp. (∆ = 0.64), Mazama temama (∆ = 0.66), Leopardus pardalis (∆ = 0.68), Dasypus novemcinctus (∆ = 0.73) and Panthera onca (∆ = 0.87). After testing 90 GLM models, the model with a lower AIC value described the activity patterns of prey and co-predators. The vegetation and water in the reserve were important variables for the cougar. However the variables that determined and modified the presence of the species were activity patterns of co-predators and the potential preys. The factors that negatively affected the presence of the species were fire, human presence, and habitat displacement to less favorable habitats to avoid jaguar.