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

We determined the instantaneous growth rate (RNA/DNA ratio) in juvenile Pelenia kraussii exposed during four weeks at 22 and 30°C. The RNA and protein levels were significantly greater (P<0.001) in samples exposed at 22°C than in those at 30°C. The RNA/DNA ratios during four week-experimental periods were three times higher in fish exposed at 22°C than in those at 30°C, suggesting a better physiological condition at low temperatures for P. kraussii.

This paper is the second part of a baseline study carried out in the coastal region near a marine ser­vice station located in Morrocoy National Park, Venezuela. Results from a physical and chemical characteriza­tion of the water and sediments of four sites located around the service station are presented. The physical and chemical factors measured in water included: temperature, salinity, specific conductance, dissolved oxygen, sat­uration percentage of dissolved oxygen, pH, total suspended solids, transparency, oil and grease, total residual petroleum hydrocarbon, vanadium and lead, total coliform bacteria, and the presence of coliform bacteria. The factors measured in sediments include: granulometry, organic material, total carbonates, vanadium, lead, oil and grease, and total hydrocarbons. In addition, the amount of vanadium and lead in sample tissue from three species which are abundant and widely distributed in each site was measured in order to evaluate the potential of these species as bio-indicators. The water in the area where this study was conducted is shallow, warm, and thermally homogeneous, with high salinity and normal pH and dissolved oxygen, and supersaturated with oxygen in cer­tain hours in sites adjacent to abundant underwater vegetation. The water is moderately turbid with a tendency towards less dissolved oxygen with increased depth. The estimated values of NMP/100 ml of the coliform fecal organisms is within legal limits even though the total number of water coliforms measured in Site 2 was ten times higher than in Site 1. This increase is associated with the proximity of Site 2 to an outflow of pre-treated sewage. The values of TRPH in the water collected from each site were low and very dose to the detection limit (O.5/ml). Vanadium was no! found, while lead was detected in 11 of the 12 samples. Compared to the values measured for Site 1, which was the local reference, only one sample had a concentration of three times the maximum baseline. The amount of lead found in all analyzed samples was acceptable, according to the standards set by the State of Washington (maximum value: 292 mg/kg), while the concentration of lead in the sediments around the supply dock were 1.5 to 3.4 times greater than the Dutch norm. It can be concluded that there is no evidence of an accu­mulation of Va or Pb in the species selected as bioindicators. An observation program is proposed in which vari­ables similar to those measured for this characterization will be studied with some modifications. A more intense sampling of some variables is recommended (lead in water and sediments, total coliform and fecal matter in con­secutive samples and in days following a high concentration of visitors) as is the elimination or minimization of other variables.

The dose dependent antiproliferative effect of an alkaloidal substance extracted from the sponge Amphimedon viridis was tested on Leishmania mexicana promastigotes. Sponges were collected in Isla Larga, Venezuela (10°20'20" - 10°24" N, 64°19' - 64°22' W), cut and dipped in methanol for vacum filtering extraection every 24 hr. The aqueous extract was separated by chromatography over silica gel. The parasites were from the Venezuelan NR strain. Their growth rate was reduced by 50 % with a dose of 10 μg/ml in 48 hr, whilst con­centrations of 30 and 40 μg/ml induce leishmanicidal action after 110 and 20 min, respectively. Lysis is preced­ed by an immediate increase in cellular volume associated with progressive damage of cellular content and the destruction of organelles. These findings suggest that one important factor associated with the antiproliferative effect of this alkaloidal substance on L. mexicana promastigotes is the loss of the plasma membrane selective per­meability.

The Mexican oyster fishery, 90% supported by the coastal lagoons of the Gulf of Mexico, has decreased drastically in the last six years as a result of anthropogenic pollution and improper management. The mussel Ischadium recurvum has proliferated and competes with oysters for space and probably food. Crassostrea vírginica and Ischadium recurvum were studied to evaluate somatic production with biometry and physiological condition indices (PCI's) during an annual cycle. A random sample of 200 organisms was taken montly for each species. Condition indices wet flesh weigth: wet shell weight ratio (WFW/WSW), dry flesh weight: wet flesh weight ratio (DFW/WFW), dry flesh wet: dry shell weight ratio (DFW/DSW), an d ash free dry weight: tissue dry weight (AFDW/TDW) were calculated. In order to stablish physiological condition and temporal variability, these indices were compared between species and months. The somatic production of mussels was higher than in oysters. This enhancement in production could be explained by: 1) Mussel uses less energy for shell production, 2) a constant recruitment ofmussel almost year-round, and 3) the mesohalin lagoon was more favourable to the mussel.

Morrocoy National Park used 19 be considered the most important continental coral reef of Venezuela However, in January of 1996, there was a massive mortality of the bentbic organisms for unknown reasons. The coral reef community was monitored since 1995, the year before the event, and yearly after that, until June 1999, by sampling linear transects and quadrats. A total of 26 hard corals were recorded in the study site (Playa Mero) in 1995 (36.56% cover), which already had some deterioration because 90.86% of the living coral cover was rep­ resented basically by four species, M annularis with 51.36%, Colpophyllia natans with 18.22%, Agaricia agaricites with 11.58% and Porites porites with 9.70%. Three months after the event, living coral cover was only 4.84% and a1gae, particularly Dyctiota spp. covered most of the surface (81.89%). Benthic organisms suffered massive mortality over the whole depth gradient and in most park reefs. Even after three years the reef commu­nity shows highly perturbed conditions, with 85% of the total cover represented by the categories: dead coral, dead coral overgrowth by algae and sand. From the initial coral rishness of the area (26 species) only nine species were observed although in very lowcover (<1%), except for M. annularis and M. franksi, which presented light­ly higher percentages.

A lot of 1600 seeds of American oyster Crassostrea virginica from the coastal lagoon La Redonda, Tabasco, Mexico was cultured in main drainage channel (S1), a secondary drainage ehannel (S2), the floodgate of a white shrimp Pennaeus vannamei pond (S3) and the marine water supply pond (S4). The seeds, with a total height and initial humid weight of 31.67±3.43 mm and 4.29±1.32 g, respectively, were cultured in suspended Nestier oyster boxes at 575 org/m2. Biological and environmental parameters were recorded after 296 days, the seeds in S4 reached height and weight values of 52.55±7.51 mm and 16.30±4.94 g, respectively. The index of physiologic condition along the experiment had a variation of 1.26% to 3.45%. In S4 the survival was 81.0%. In the. other places the mortality was total after 90 days.

A population of the conch Strombus gigas was sampled in 109 transects (100X10 m each) for an area of 109 000 m2 (eight surveys in 1998 and six in 1999) in Yucatan, Mexico; S. gigas was the most abundant conch species (97% of individuals)and ocurred at depths of 0.5-18 m. Mean density was 0.0084 individuals/m2 (Standard deviation SD=0.0138, n=1910). Maximum density (0.015 individuals/m2) was at 0.5-2 m and minimal (0.001 individuos/m2) at 16-18 m. Shell length was120-290 mm (mena=211.6, SD=26, n=1136). Shell lip thickness, measured only in adults, was 1-28 mm (mean=8.7, SD=7.5, n=1136).

Después de comunicarnos con varios cientí­ficos de la región , nos causó una gran frustra­ción constatar la falta de información que exis­te entre nuestros países, así como conocer la gran cantidad de trabajos científicos de gran re­levancia que permanecen aún inéditos. Muchos trabajos se encuentran como tesis de grado, in­formes técnicos, o publicados en revistas loca­les de distribución casi inaccesible a la comuni­dad científica regional. Por esta razón, hemos decidido establecer la "Sociedad Latinoamericana de Arrecifes Coralinos". El objetivo principal es agrupar a los investigadores de las áreas de biología, eco­logía, evolución, paleontología, geología, contaminación, manejo, y conservación de arreci­fes coralinos de la región latinoamericana. Esto incluye estudios básicos o aplicados sobre los organismos, com unidades y procesos de los arrecifes coralinos.

The Mississippi River is the largest river in the United States and discharges substantial amounts of nutrients, organic carbon, and sedi­ments onto the Texas-Louisiana continental shelf in the northern Gulf of Mexico. As a ba­sic part of an initiative to describe processes at the sediment-water interface in the northern Gulf of Mexico shelf ecosystem we measured sediment grain size and per cent total organic carbon. This paper reports sediment grain size characteristics and per cent carbon, and makes preliminary associations between these varia­bles and carbon utilization by the benthos (cal­culated from sediment oxygen consumption ra­tes) and macrofauna biomass.

Stages from oviposition to veliger hatching are described for Strombus pugilis under laboratory conditions. Two egg masses from Playa Seyba, México, (20"45' N, 91°45' W) were used (three sub-samples per mass). Each sub-sample was immersed in a 11 container at 29 ± 1°C. This description is based on stages known from Strombus gigas, which include number of: fertilized eggs, morulae, gastrulae; trochophore larvae with slow movements, larvae with primordium foot, larvae with eyes, larvae with statocyst and veliger larvae. Eggs with first division appeare d five hours after oviposition in the three replicates of each mass, although in greatest number in one of the egg masses. Trochophore larvae with slow move­ments appear after 50-54 hours and veligers hatch after 90 hours.