Ulva ohnoi (Ulvales, Chlorophyta) como potencial biofiltro en sistemas de AMTI-RAS: Influencia del pH, reserva alcalina y concentraciones de N y P en su cultivo

En el presente trabajo se estudia la influencia de las variaciones de pH, reserva alcalina, concentraciones de nitrógeno y fósforo en el crecimiento en cultivo de Ulva ohnoi con el fin de optimizar su integración en sistemas de AMTI-RASPostprint (published version

Juvenile king scallop, Pecten maximus, is potentially tolerant to low levels of ocean acidification when food is unrestricted.

The decline in ocean water pH and changes in carbonate saturation states through anthropogenically mediated increases in atmospheric CO2 levels may pose a hazard to marine organisms. This may be particularly acute for those species reliant on calcareous structures like shells and exoskeletons. This is of particular concern in the case of valuable commercially exploited species such as the king scallop, Pecten maximus. In this study we investigated the effects on oxygen consumption, clearance rates and cellular turnover in juvenile P. maximus following 3 months laboratory exposure to four pCO2 treatments (290, 380, 750 and 1140 µatm). None of the exposure levels were found to have significant effect on the clearance rates, respiration rates, condition index or cellular turnover (RNA: DNA) of individuals. While it is clear that some life stages of marine bivalves appear susceptible to future levels of ocean acidification, particularly under food limiting conditions, the results from this study suggest that where food is in abundance, bivalves like juvenile P. maximus may display a tolerance to limited changes in seawater chemistry

Marine Biodiversity in the Caribbean: Regional Estimates and Distribution Patterns

This paper provides an analysis of the distribution patterns of marine biodiversity and summarizes the major activities of the Census of Marine Life program in the Caribbean region. The coastal Caribbean region is a large marine ecosystem (LME) characterized by coral reefs, mangroves, and seagrasses, but including other environments, such as sandy beaches and rocky shores. These tropical ecosystems incorporate a high diversity of associated flora and fauna, and the nations that border the Caribbean collectively encompass a major global marine biodiversity hot spot. We analyze the state of knowledge of marine biodiversity based on the geographic distribution of georeferenced species records and regional taxonomic lists. A total of 12,046 marine species are reported in this paper for the Caribbean region. These include representatives from 31 animal phyla, two plant phyla, one group of Chromista, and three groups of Protoctista. Sampling effort has been greatest in shallow, nearshore waters, where there is relatively good coverage of species records; offshore and deep environments have been less studied. Additionally, we found that the currently accepted classification of marine ecoregions of the Caribbean did not apply for the benthic distributions of five relatively well known taxonomic groups. Coastal species richness tends to concentrate along the Antillean arc (Cuba to the southernmost Antilles) and the northern coast of South America (Venezuela – Colombia), while no pattern can be observed in the deep sea with the available data. Several factors make it impossible to determine the extent to which these distribution patterns accurately reflect the true situation for marine biodiversity in general: (1) highly localized concentrations of collecting effort and a lack of collecting in many areas and ecosystems, (2) high variability among collecting methods, (3) limited taxonomic expertise for many groups, and (4) differing levels of activity in the study of different taxa

Heavy metals in the clam Tivela mactroides Born, 1778 (Bivalvia: Veneridae) from coastal localities with different degrees of contamination in Venezuela

We compared heavy metal levels (manganese, iron, zinc, cadmium, copper, chromium, and lead) in tissues and shells of juveniles (13±2.2 mm), medium-size organisms with mature gonads (25±4.1mm), and adults (35±1.2 mm) of the clam Tivela mactroides from three different locations along the Venezuelan coast: Playa Güiria, on the northeastern coast, was not affected by environmental pollution, but Río Chico and Boca de Paparo, influenced by the Tuy River on the central coast, were. Heavy metal concentrations were related to shell size, with significant differences among populations and shell sizes. Specimens from Boca de Paparo and Río Chico had the highest heavy metal concentrations in tissues and shells, in contrast with the levels found in specimens from Playa Güiria, in which chromium and lead were absent. The high heavy metal concentrations found in tissues from specimens collected at Boca de Paparo and Río Chico were possibly of anthropogenic origin and generated by the Tuy River. The environmental conditions at Boca de Paparo may have favored the bioaccumulation of most heavy metals in specimen tissues. At Playa Güiria, however, the heavy metal concentrations were found to be within a natural range. Our results show that T. mactroides is a good biological indicator of the presence of heavy metals in the littoral waters they inhabit

Biochemical composition of nauplii and metanauplii of Artemia sp. (Crustacea, Anostraca) from the Araya saltworks, northeastern Venezuela

In this work, we compared the proportion of proteins, lipids, carbohydrates and fatty acids in populations of Artemia sp. from the Araya saltworks in northeastern Venezuela, during two stages (nauplii and metanauplii) of their development. The population of Artemia franciscana from San Francisco Bay (USA) was used as reference because of its wide use in aquaculture. The organisms of both populations showed significant differences in protein, lipid, carbohydrate and phospholipid contents between both stages; however, no significant differences were established between both populations. The highest protein concentrations were found in metanauplii: 67% for Araya and 56% for San Francisco. The highest concentrations of lipids (22% and 24%), carbohydrates (17% and 11%) and phospholipids (26% and 35%) were found in nauplii for both populations. Cholesterol esters, cholesterol, triglycerids, and n-3 and n-6 fatty acids were significantly different between stages and between populations. Cholesterol esters, and n-3 and n-6 fatty acids were higher in San Francisco metanauplii, with values of 37%, 11% and 7%, respectively. The highest triglycerid concentration (39%) was found in San Francisco nauplii and the highest cholesterol concentration in Araya metanauplii (50%). The results suggest that the Artemia population from the Araya saltworks contains the necessary elements to cover the nutritional requirements of fish larvae and marine crustaceans under culture

Evaluation of culture enclosures for the mangrove oyster Crassostrea rhizophorae suspended from raft and long-line systems

 We evaluated the growth and survival of the mangrove oyster Crassostrea rhizophorae (30 mm maximum length) reared in two suspended-culture systems (raft and long-line) using three types of enclosures (oyster enclosures, lantern nets and enclosures based on crates used to transport fish), at a density of 750 ind m–2, in La Restinga Lagoon, Margarita Island, Venezuela, over the course of six months. No significant differences were found in shell growth (length and mass) due to the system and enclosures used; however, raft-cultured oysters showed better tissue growth. At the end of the study, the oysters in lantern nets suspended from rafts obtained a tissue mass that was around 40% higher than that of the rest of the oysters cultured in the other enclosures. Significant differences in oyster survival were not observed for the raft and long-line systems used, but the cumulative survival at the end of the study was significantly higher for the oyster enclosures (52–56%) than for the lantern nets (36–39%) and fish crates (24–25%). We therefore recommend employing rafts and discarding the use of crate-type enclosures in the culture of C. rhizophorae in lagoon systems

Effect of density on growth and secondary production of Euvola (Pecten) ziczac juveniles, under suspended culture conditions

The effect of density on growth and secondary production of Euvola ziczac was studied under suspended culture conditions from June 1988 to January 1989. Seven different densities were examined, using juveniles from 9.6 k 0.3 mm long and 5.17 ± 0.6 mg dry weight, which were previously cultivated under hatchery conditions. The growth rate in size and biomass was relatively fast in the group containing 200 specimens/m2 (5.2 mm and 85.94 mg), followed by the lots with 400, 600 and 800 specimens/m2 (4.0 mm and 52.89 mg). The lots with 1,600, 2,400 and 3,200 specimens/m2 showed slow growth. The maximum biological load tolerated was found to be 120 ± 10 g/m2, after which individual growth slowed down and mortality increased. The highest secondary production was obtained in the group with 2,400 specimens/m2 (5.71 mg/m2/day). Density management during the nursery stage of E. ziczac is discussed