Temporal variation of the concentration and biochemical composition of seston within the Humboldt Current System off northern Chile (21°S)

Seasonal differences in the concentration and biochemical composition of seston have been assessed for the first time in the Humboldt Current System off northern Chile (21°S). The study comprised four seasonal surveys in the Bay of Chipana, including the summer and winter of 2006 and 2007, when El Niño 2006 and La Niña 2007 developed. Protein, lipid, carbohydrate and biogenic silica contents were measured in samples collected at four selected depths. The highest protein, lipid and carbohydrate concentrations were found at the fluorescence maximum (between 10 and 15 m depth), whereas the highest biogenic silica concentration was found 1 m above the seabed. When El Niño started developing, every variable showed low values throughout the water column; however, the lowest values were found when La Niña conditions dominated, together with low oxygen concentrations. Samples collected within the oxygen minimum zone (65 m depth) showed the lowest values for the water column and the lowest seasonal variations. After the evident decline coincident with El Niño 2006, the abundance and biochemical quality (high protein and lipid contents) of seston recovered earlier in the surface layer (upper 15 m) than at other depths.     

Physicochemical properties of non-living water hyacinth (Eichhornia crassipes) and lesser duckweed (Lemna minor) and their influence on the As(V) adsorption processes

Eichhornia crassipes (Ec) and Lemna minor (Lm) are aquatic plants. They are considered as weeds of the water and approach being a scourge in many parts of the world, choking waterways and hindering transport upon them. At the same time they are known to readily remove heavy metal ions from water. This paper considers the use of non-living plants as novel and inexpensive biosorbent for the removal of As(V) from watersheds. In the first place they were conditioned and characterised to determine their physicochemical and surface properties and in the second place their adsorption properties for As(V) from aqueous solution were evaluated considering the toxicity of this metalloid in the environment. It describes the methodology to prepare the non-living biomasses; the physicochemical characterisation by SEM, XRD, FTIR, TGA analyses and surface characterisation of Ec and Lm by specific surface, hydration kinetic, point of zero charge determination by mass titration, active site density and XPS analysis are described. Both studied biomasses were found to be potential bio-sorbents for arsenic ions from aqueous solution. According to their efficiency to remove arsenic, they can be used in a very low cost metalloid ions removal system.     

Phosphorous cycling and biogeochemistry in a Venezuelan-flooded savanna

In 1970, a programme of land recuperation started in Venezuelan savannas, strongly affected by the seasonality of precipitation; therefore, a network of dykes has been built to alleviate the floods and retain water throughout the dry period. Under the dyked system, the environment has been altered, allowing a change in the herbaceous vegetation towards aquatic species and an increase in primary production. It is assumed that a considerable quantity of nutrients is lost from the ecosystem through the floodgates, a situation that could be worsened with the climate change. This contribution describes the atmospheric input and total output in stream run-off of phosphorous (P) in a flooded savanna. Internal pools of the biogeochemical cycle of P associated with terrestrial compartments are described. In the flooded savanna, a large amount of P is immobilised (29.6?kg?ha^?1) in their above ground biomass by grasses, and in soil microbial biomass. The P budget was nearly balanced, as measured losses were cancelled out by the inputs in rainfall. Soils act as a sink, retaining P coming either from precipitation or from desorption/mineralisation processes. That interruption can be maximised, and losses of P and other nutrients can be minimised with an adequate management of the floodgate.     

Heavy Metals in Macroalgae of Havana's Northern Littoral,Cuba

Copper, iron, lead, manganese, and zinc contents were determined in various phyla of macroalgae typical of the rocky mesolittoral zone of Cuba and widely distributed in the Caribbean Region. the samples were collected in different zones along the shores of Havana City which are more or less influenced by anthropogenic activities. Differences in metal contents were observed due to seasonal variations and differences between sampling sites. of the analyzed species, only one brown alga, Padina vickersiae is considered as a suitable candidate for the monitoring of metal contamination.     

Temporal patterns of settlement, recruitment and post-settlement losses in a rocky reef fish assemblage in the South-Western Mediterranean Sea

Post-settlement events can significantly alter the density distribution of settlers and subsequently the adult population structure. The temporal and inter-annual variability of settlement and the effects of mortality on recruitment were investigated across 2 years in the vicinities of Cabo de Palos–Islas Hormigas Marine Reserve by visual census and light trap sampling. Settlement was seasonal with greater species richness and abundance in summer. Although temporal synchronization was observed between larval supply and settlement, densities of settlers could not be predicted from post-larval abundances. Timing of settlement was consistent between years but with high inter-annual variation in abundance. High mortality (~80 %) and general decoupling between post-larval and settlement stages suggest that early mortality is driving such patterns. Nevertheless, indications of habitat-mediated mortality were found for benthic species such as Symphodus and Diplodus, highlighting the importance of habitat in shaping population demography.     

How wave exposure, group size and habitat complexity influence foraging and population densities in fishes of the genus Halichoeres (Perciformes: Labridae) on tropical rocky shores

Wave exposure and habitat complexity have been used to explain variations in the distribution patterns and behavior of many reef fishes. This study analyzed the influence of both factors on density and foraging activity, and the influence of group size on foraging in three species of the genus Halichoeres (Labridae) on tropical rocky shores. It was shown that initial phases (IP) and terminal phases (TP) Halichoeres, were influenced by wave exposure, although foraging in Halichoeres brasiliensis TP was not influenced by wave exposure. The IP in all three species were positively associated with rugosity and algal cover while the TP was positively associated with depth. Habitat complexity also influences foraging in these species. Group size influenced foraging activity, except in H. brasiliensis TP. We also found variations in microhabitat patches used for foraging between species and differences in the stomach contents between species and phases, showing that functional roles change in response to ontogenetic shifts.     

Ecological niche segregation among five toothed whale species off the NW Iberian Peninsula using ecological tracers as multi-approach

This study aims to assess niche segregation among the five main toothed whales that frequent the NW Iberian Peninsula waters: the common dolphin, the harbour porpoise, the bottlenose dolphin, the striped dolphin and the long-finned pilot whale. We used cadmium (Cd) and stable isotope ratios (δ¹³C and δ¹⁵N) as ecological tracers to assess degree of segregation in diet/trophic level and in foraging habitat, over various time-scales. δ¹³C values highlighted different habitats, while Cd concentrations highlighted feeding differences between oceanic and neritic species. Moreover, δ¹⁵N values suggest different trophic levels of prey targeted within oceanic and neritic species. Hence, results revealed long-term ecological segregation among five toothed whales that coexist in the NWIP and demonstrated the ability of ecological tracers to discriminate ecological niches among closely related species.     

Temporal and spatial variability in coral recruitment on two Indonesian coral reefs: consistently lower recruitment to a degraded reef

Corals are the primary reef-building organisms, therefore it is key to understand their recruitment patterns for effective reef management. Coral recruitment rates and juvenile coral abundance were recorded in the Wakatobi National Marine Park, Indonesia, on two reefs (Sampela and Hoga) with different levels of environmental degradation (12.5 vs. 44 % coral cover with high and low sedimentation rates, respectively) to examine consistencies in recruitment patterns between years and seasons. Recruitment was measured on multiple panels at two sites on each reef (6–7 m depth) and cleared areas of natural reef. Although coral recruitment was twofold higher in 2008–2009 than in 2007–2008, and seasonal differences were identified, consistent significant differences in recruitment rates were found between the two reefs even though they are separated by only ~1.5 km. Recruitment rates and juvenile abundance were lower on the more degraded reef. These patterns are likely a consequence of differential pre- and post-settlement mortality as a result of the high sedimentation rates and degraded conditions and possibly reduced larval supply.