Lysosomal responses in mussel digestive cells are widely accepted as effective biomarkers that respond to pollutant exposure, as well as to natural factors (tide, food, temperature). The effects of tide and season on digestive cell lysosomes in mussels were determined in different transect and transplant experiments on mussels at different tide levels and in winter and summer. We measured lysosomal enlargement through the lysosomal structural changes (LSC) test after β-glucuronidase (β-Gus) histochemistry and membrane destabilisation through the lysosomal membrane stability (LMS) test after hexosaminidase (Hex) histochemistry. A marked gradient along the intertidal zone, which was more prominent in winter than in summer, was found in lysosomal size and membrane stability. A transplant experiment revealed that digestive cell lysosomes respond rapidly to immersion of mussels. The study of the time-course changes in mussels from high tidemark level indicated that lysosomes respond very promptly to air exposure conditions. We suggest that the lysosomal changes observed are the result of the digestive process in parallel with tide. Since such natural variability might mask the effects of pollution, we conclude that a standardised sampling protocol -which should include the use of mussels from low intertidal levels -is needed.

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This study aimed to evaluate potential differences in coral spawning behavior between a fringing coastal reef and an offshore reef in the southern Caribbean. For this, scleractinian and gorgonian colonies (N = 324) of 21 species were mapped along eight transects, each 10-m long, at two study sites located in Morrocoy and Los Roques National Parks, Venezuela. Observations were made between 19:30 and 23:00 from August 23 to 30 and from September 26 to 30, 2002. Ninety one colonies belonging to six hard coral and seven octocoral species spawned or planulated during this period. We were unable to observe any signs of reproductive activity in 95 colonies of nine species different from those that reproduced. Despite the differences in environmental conditions between the two sites, we observed high synchrony in the spawning behavior of seven coral species common to both reefs. The most striking result was the ability of colonies of Montastraea faveolata and Eusmilia fastigiata to split spawn up to three times, either in consecutive nights or in different months.

<span>Durante las últimas décadas las anomalías térmicas han sido más frecuentes y severas en el Caribe, quedando pocos arrecifes exentos de eventos masivos de blanqueamiento (EMB). En el Parque Nacional Los Roques, Venezuela, un archipiélago poco afectado previamente por EMB, la temperatura del agua a 5m de profundidad alcanzó 30,85°C en septiembre 2010, y fue &gt;29,0°C entre mediados de agosto y la primera semana de noviembre en cuatro arrecifes. El 72% de 563 colonias de escleractinios estaban blanqueadas o pálidas para octubre de 2010, mientras que para febrero 2011, el 46% de las colonias aún estaban afectadas. Para febrero 2011, la cobertura béntica coralina promedio disminuyó de 45 a 31%. Además, los arrecifes mostraron una alta prevalencia (de hasta 16%) de enfermedad de banda negra en Octubre 2010, y de plaga blanca (11%) en Febrero 2011. Como consecuencia, es probable que la mortalidad coralina resulte mayor a la reportada acá. Sin embargo, Los Roques es poco afectado por perturbaciones antropogénicas y cuenta con un alto reclutamiento de corales, lo cual podría contribuir a su recuperación.</span>

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