Are tropical coastal reefs sinks or sources of mesozooplankton? A case study in a Brazilian marine protected area

International audienceIn spite of the paramount ecological and socioeconomic relevance of tropical reef ecosystems, the dynamics of their meroplankton abundance remain poorly characterized. The small-scale distribution and detailed analysis of individual biomass of mesozooplankton were studied in the coastal reefs of Tamandaré (Brazil). Mesozooplankton (> 300 μm) was collected during nocturnal ebb tides at new moon, using three different devices to sample at three different environments: a standard ring net that was towed at subsurface, the Channel Midwater Neuston Net that collected at midwater in channels between patch reefs and the Reef Edge Net that captured organisms that are washed by ebb currents from reef tops toward the reef edge. Samples were analyzed using a ZooScan to obtain abundances and biovolume of each taxonomic group. Specific biomass measurements were taken to obtain allometric equations used to calculate zooplankton biomass from biovolume. The mesozooplankton were significantly more abundant at subsurface and at the reef edge compared to channel environments. The high abundance of organisms at reef edges suggests a low predation pressure on zooplankton at near-bottom areas, since the reefs of Tamandaré present a low coverage of planktivorous corals, being dominated by macroalgae. These results show that rather than sinks these ecosystems may be considered important sources of zooplankton available for planktivorous species. Regarding zooplankton composition, we found large amounts of initial stages of meroplanktonic larvae and newly hatched fish eggs, which presented consistently greater abundances compared to holoplankton and emergent benthic taxa. Decapod larvae were the most abundant group of the meroplankton, but cirripedian nauplii, stomatopod larvae, fish larvae and fish eggs were also abundant. More than 50% of the total biomass was due to meroplankton taxa, mainly composed of decapod larvae. This study indicates that the contribution of meroplankton to mesozooplankton composition and biomass off tropical reefs may have been underestimated

Easy Method for Removal of Cyanogens from Cassava Leaves with Retention of Vitamins and Omega-3 Fatty Acids

Currently there is a crescent interest regarding the use of vegetable by-products for food fortification, in order to improve its nutritional quality. Cassava leaves are suitable as nutritional additives, however their cyanide content must be reduced to below 10 mg kg-1 of dry product. Thus, it was developed a method in drying laboratory oven which is able to reduce 99.85% of cyanide present in manioc leaves (from 35 mg kg-1 to 0.05 mg kg-1) while being 509% faster than the traditional method, and without substantial loss of omega-3 fatty acids and β-carotene

Obtaining of xanthan gum impregnated of cellulose microfibrils derived from sugarcane bagasse

Xanthan gum (XG) is a microbial exopolysaccharide that occupies a prominent place in the market because of its unique properties compared with other microbial gums. When lignocellulosic materials such as sugarcane bagasse (SCB) are used as a carbon source, the degradation of the SCB material can be partial, retaining microfibrils of cellulose in the fermentation broth. These microfibrils can be incorporated into the XG structure. The aim of this work was to select the best concentration of SCB to produce XG and to analyze the characteristics of the biopolymer obtained. The XG produced in the best condition was added to biodegradable films as a reinforcing agent. The SCB was evaluated at the following concentrations: 2, 4, 6, 8 and 10% w/w. The XG produced with 4% w/w SCB provided the best XG, not only for production but also for polymer characteristics. Visualization with transmission electron microscopy (TEM) established the presence of microfibrils in the polysaccharide structure, and the incorporation of XG with microfibrils provided a flexible film with enhanced mechanical properties.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Developing new approaches for detecting and preventing Aedes aegypti population outbreaks: basis for surveillance, alert and control system

A new approach to dengue vector surveillance based on permanent egg-collection using a modified ovitrap and Bacillus thuringiensis israelensis(Bti) was evaluated in different urban landscapes in Recife, Northeast Brazil. From April 2004 to April 2005, 13 egg-collection cycles of four weeks were carried out. Geo-referenced ovitraps containing grass infusion, Bti and three paddles were placed at fixed sampling stations distributed over five selected sites. Continuous egg-collections yielded more than four million eggs laid into 464 sentinel-ovitraps over one year. The overall positive ovitrap index was 98.5% (over 5,616 trap observations). The egg density index ranged from 100 to 2,500 eggs per trap-cycle, indicating a wide spread and high density of Aedes aegypti (Diptera: Culicidae) breeding populations in all sites. Fluctuations in population density over time were observed, particularly a marked increase from January on, or later, according to site. Massive egg-collection carried out at one of the sites prevented such a population outbreak. At intra-site level, egg counts made it possible to identify spots where the vector population is consistently concentrated over the time, pinpointing areas that should be considered high priority for control activities. The results indicate that these could be promising strategies for detecting and preventing Ae. aegypti population outbreaks