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Long-term and seasonal changes in production and respiration were surveyed in the Valle de Bravo reservoir, Mexico, in a period during which high water-level fluctuations occurred (2006-2015). We assessed the community metabolism through oxygen dynamics in this monomictic water-body affected by strong diurnal winds. The multiple-year data series allowed relationships with some environmental drivers to be identified, revealing that water level-fluctuations strongly influenced gross primary production and respiratory rates. Production and respiration changed mainly vertically, clearly in relation to light availability. Gross primary production ranged from 0.15 to 1.26 gO2 m-2 h-1, respiration rate from -0.13 to -0.83 gO2  m-2 h-1 and net primary production from -0.36 to 0.66 gO2  m-2 h -1 within the production layer, which had a mean depth of 5.9 m during the stratification periods and of 6.8 m during the circulations. The greater depth of the mixing layer allowed the consumption of oxygen below the production layer even during the stratifications, when it averaged 10.1 m. Respiration below the production layer ranged from -0.23 to -1.38 gO2 m-2 h-1. Vertically integrated metabolic rates (per unit area) showed their greatest variations at the intra-annual scale (stratification-circulation). Gross primary production and Secchi depth decreased as the mean water level decreased between stratification periods. VB is a highly productive ecosystem; its gross primary production averaged 3.60 gC m-2 d-1 during the 10 years sampled, a rate similar to that of hypertrophic systems. About 45% of this production, an annual average net carbon production of 599 g C m-2 year-1, was exported to the hypolimnion, but on the average 58% of this net production was recycled through respiration below the production layer. Overall, only 19% of the carbon fixed in VB is buried in the sediments. Total ecosystem respiration rates averaged -6.89 gC  m-2 d-1 during 2006-2015, doubling the gross production rates. The reservoir as a whole exhibited a net heterotrophic balance continuously during the decade sampled, which means it has likely been a net carbon source, potentially releasing an average of 3.29 gC m-2 d-1 to the atmosphere. These results are in accordance with recent findings that tropical eutrophic aquatic ecosystems can be stronger carbon sources than would be extrapolated from temperate systems, and can help guide future reassessments on the contribution of tropical lakes and reservoirs to carbon cycles at the global scale. Respiration was positively correlated with temperature both for the stratification periods and among the circulations, suggesting that the contribution of C to the atmosphere may increase as the reservoirs and lakes warm up owing to climate change and as their water level is reduced through intensification of their use as water sources.

The distribution area of Halophila engelmanni is enlarged for Cuban shelf. 83 records of the presence of this species were found in 67 sites of the marine Cuban shelf. [ABSTRACT FROM AUTHOR]

A checklist of marine macroalgae of the Ana Maria Gulf, Southeast shelf of Cuba, is presented for the first time. As results of the collection, 75 taxa, 24 Rhodophyta, 14 Ochrophyta (Phaeophyceae) and 37 Chlorophyta, were obtained. All species are typical from the Caribbean Sea. [ABSTRACT FROM AUTHOR]

In this study, we examined physicochemical parameters and an inventory of species in the Marine Protected Area of Gran Banco de Buena Esperanza, in July 2011 and July 2012. Four sites in seagrass beds and four sites in muddy slopes were established. We measured salinity, temperature, dissolved oxygen and dissolved nutrients. The inventory was carried out using visual census. Average temperature was 30.8°C, salinity was 37.2. Dissolved oxygen ranged from 5.3 to 8.0 ml/l. The average concentration of dissolved inorganic nitrogen was 13.2 ± 9.1 µM. In seagrass beds 21 species of macroalgae, 41 species of non-sessile invertebrates and 23 species of stony corals were identified with Cladocora arbuscula and Manicina areolata dominating. We also identified colonies of Acropora cervicornis and Acropora prolifera, with no presence of Acropora palmata. Among the fish, the Lutjanidae family was predominant. In the muddy slopes 31 species of macroalgae and two angiosperms were identified. There were 45 species of non-sessile invertebrates and 42 of stony corals, with Millepora alcicornis, Porites astreoides and the genus Oculina prevailing. The average density of Diadema antillarum was 14 individual. 10m-2. The predominant fish families were Serranidae and Lutjanidae. These results provide the basis for future ecological research and have generated new hypotheses directed mainly towards the presence of possible new species and hybridization and evolution studies, focused mainly on the genus Acropora. [ABSTRACT FROM AUTHOR]