Chemical variability within the marine sponge Aplysina fulva

Dibromotyrosine-derived metabolites are of common occurrence within marine sponges belonging to the order Verongida. However, previous chemical analysis of crude extracts obtained from samples of the verongid sponge Aplysina fulva collected in Brazil did not provide any dibromotyrosine-derived compounds. In this investigation, five samples of A. fulva from five different locations along the Brazilian coastline and one sample from a temperate reef in the South Atlantic Bight (SAB) (Georgia, USA) were investigated for the presence of bromotyrosine-derived compounds. All six samples collected yielded dibromotyrosine-derived compounds, including a new derivative, named aplysinafulvin, which has been identified by. analysis of spectroscopic data. These results confirm previous assumptions that dibromotyrosine-derived metabolites can be considered as chemotaxonomic markers of verongid sponges. The isolation of aplysinafulvin provides additional support for a biogenetic pathway involving an arene oxide intermediate in the biosynthesis of Verongida metabolites. It cannot yet be established if the chemical variability observed among the six samples of A.fulva collected in Brazil and the SAB is the result of different environmental factors, distinct chemical extraction and isolation protocols, or a consequence of hidden genetic diversity within the postulated morphological plasticity of this species. (C) 2007 Elsevier Ltd. All rights reserved.

Investigation of Iron (III) desferrioxamine B oxalate ligand exchange by UV-vis spectroscopy: the next step in developing a quantitative analytical method for measuring bioavailable iron in marine ecosystems

To date there are no analytical techniques designed to exclusively measure bioavailable iron in marine environments. The goal of this research is to develop such a technique by isolating the bioavailable iron using the terrestrial siderophore desferrioxamine B (DFB). This project contained many challenging aspects, but the specific goal of this study was to develop a robust analytical technique for quantification of Fe(III)-DFB complexes at nanomolar concentrations. Past work showed that oxalate (Ox) promotes photodissociation of Fe(III)-DFB to Fe(Il), and we are specifically interested in the mechanism of this process. A model was developed using known thermodynamic constants for Fe(III)-DFB and Fe(III) oxalato complexes and adjusting for ionic strength. The model was confirmed by monitoring the UV-VIS absorbance of the system at a variety of oxalate concentrations and pH. The model did not include ternary complexes. Next., the rate of Fe(1I) production during UV irradiation was examined. The results showed that the rate of Fe(II) production was based entirely on the [Fe(Ox)?]3- speciation, and that reoxidation of Fe(II) occurred via reactive oxygen intermediates. This reoxidation could be avoided by either decreasing the oxygen concentration or by adding a Fe(II) stabilizing reagent, such as ferrozine. Further studies need to be done to confirm that these results apply at sub nanomolar concentrations, and the issue of Fe(II) reoxidation at lower Fe concentrations needs to be addressed.

DNA barcodes identify marine fishes of São Paulo State, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Reproductive biology and recruitment of Xiphopenaeus kroyeri in a marine protected area in the Western Atlantic: implications for resource management

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mesocosm experiment on the impact of invertebrate predation on zooplankton of a tropical lake

Invertebrate predation on zooplankton was investigated in mesocosms in the shallow tropical Lake Monte Alegre, Sauo Paulo State, Brazil, in the summer of 1999. Two treatments were applied: one with natural densities of prey and the predators Chaoborus brasiliensis and the water mite Krendowskia sp. (Pr+), and another without predators (Pr-). Three enclosures (volume: 6.6 m(3) of water per enclosure) per treatment were installed in the sediment of the deepest area of the lake (5.0 m). At the beginning, Chaoborus larvae were present in Pr- enclosures, because of technical difficulties in preventing their entrance, but they virtually disappeared in the course of the experiment. Water mites were almost absent in Pr- enclosures. Chaoborus predation negatively influenced the Daphnia gessneri population, but not the populations of the copepods Tropocyclops prasinus and Thermocyclops decipiens and the rotifers Keratella spp. Death rates of Daphnia were generally significantly higher in the Pr+ treatment; Daphnia densities increased after the disappearance of Chaoborus in Pr-. Copepod losses to predation in the experiment may be compensated by higher fecundity, shorter egg development time, and lower pressure on egg-bearing females, resulting in a lower susceptibility to Chaoborus predation. The predation impact of water mite on microcrustaceans and rotifers in the experiment was negligible.

Coastal Marine Mapping as an Ecosystem Based Management - the case study of the Baixada Santista Region - São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of atypical rainfall on lotic zooplankton: comparing downstream of a reservoir and tributaries with free stretches

To contribute to the knowledge of lotic zooplankton from dammed and free stretches, we tested the hypothesis that the ecological attributes are different between these environments, which are subjected to several effects caused by different hydrological conditions. The study was carried out in the low Iguacu river, a large hydrographic basin in the south of Brasil. Two samplings were performed, one in the dry period (April/04) and the other in the atypical rainy period (July/04), in five stations downstream a large reservoir, and other 12 stations in four tributaries representing the upper, intermediate and low regions of each river. The observations suggest a clear spatial distribution of zooplankton in lotic stretches subjected or not to damming, mainly due to the effects of physical, chemical and biological variables. Furthermore, the atypical rainfall promoted alterations in community structure when compared to the dry period.

Gender, tourism, and participatory appraisals at the Corumbau Marine Extractive Reserve, Brazil

The Corumbau Marine Extractive Reserve was created in a region of rich biodiversity, located in the South of Bahia State, Brazil, to meet the revindications of artisanal fishermen in a context of increasing predatory industrial fisheries. The aim of the Marine Extractive Reserve is to improve the sustainability of fisheries stocks and the economy of artisanal fishermen's families, protecting the local biodiversity for the locals' collective use. However, at Corumbau the natives are facing social problems that have increased due to tourism growth. The present research contributes to the Management Plan in sectors that are crucial to assess the aspirations and subjective aspects related to the natives' daily life at individual, familiar and communitary levels. The Participatory Appraisal with a Gender Equity Perspective (PAGP) was applied to five communities at RESEX Corumbau, showing, by gender, the greatest problems artisanal fisheries' families are facing. Tourism is growing in the area, reflecting the residents different and contradictory interests. It can develop commerce and jobs, but also intensify some social and environmental problems in this area. © Society for Human Ecology.

Vibrio cholerae O1 detection in estuarine and coastal zooplankton

Vibrio cholerae is an autochthonous marine bacterium, and its association with diverse planktonic crustaceans has been extensively investigated; however, the presence of V. cholerae on individuals of most phyla of planktonic animals is still incompletely understood. The objective of this study was to analyze the distribution of V. cholerae serogroup O1 associated with specific zooplankton taxa in an estuary and the adjacent continental shelf of the southeastern Brazilian coast. The occurrence of the bacterium was assessed in zooplankton samples, specifically on the most abundant taxa, using direct fluorescence assay (DFA) and direct viable count-direct fluorescence assay (DVC-DFA) methods. Vibrio cholerae O1 was detected in 88% of samples collected from the Santos-Bertioga estuary and in 67% of samples from the shelf. The salinity of the estuarine water ranged from 21.8 to 34.6, significantly lower than the shelf water which was 32.1-36.1. Salinity was the only environmental variable measured that displayed a significant correlation with the presence of V. cholerae (P < 0.05). Vibrio cholerae O1 was detected in chaetognaths, pluteus larvae of echinoderms and planktonic fish eggs (Engraulidae), all new sites for this bacterium.

Laser Optical Plankton Counter and Zooscan intercomparison in tropical and subtropical marine ecosystems

Two recently developed instruments, the Laser Optical Plankton Counter (LOPC) and the Zooscan, have been applied to study zooplankton biomass size spectra in tropical and subtropical marine ecosystems off Brazil. Both technologies rely on optical measurements of particles and may potentially be used in zooplankton monitoring programs. Vertical profiles of the LOPC installed in a 200 mu m ring net have been obtained from diverse environmental settings ranging from turbid and nearshore waters to oligotrophic open ocean conditions. Net samples were analyzed on the Zooscan and counted under a microscope. Particle biovolume in the study area estimated with the LOPC correlated with plankton displacement volume from the net samples, but there was no significant relationship between total areal zooplankton biomass determined with LOPC and the Zooscan. Apparently, normalized biomass size spectra (NBSS) of LOPC and Zooscan overlapped for particles in the size range of 500 to 1500 mu m in equivalent spherical diameter (ESD), especially at open ocean stations. However, the distribution of particles into five size classes was statistically different between both instruments at 24 of 28 stations. The disparities arise from unequal flow estimates, from different sampling efficiencies of LOPC tunnel and net for large and small particles, and possibly from the interference of non-zooplankton material in the LOPC signal. Ecosystem properties and technical differences therefore limit the direct comparability of the NBSS slopes obtained with both instruments during this study, and their results should be regarded as complementary.

Comparison of zooplankton community structure between impacted and non-impacted areas of Paranagua Bay Estuarine Complex, south Brazil

We analysed the seasonal distribution of the zooplankton community in an anthropogenically impacted area (Paranagua Bay) and a non-impacted area (Laranjeiras Bay) of the Paranagua Bay Estuarine Complex. Large phytoplankton (&gt;50 mu m) and zooplankton were collected every two months, between August 2003 and June 2004. The phytoplankton community was numerically dominated by diatoms (78%) and dinoflagellates (19%). Zooplankton abundance varied between 670 and 100,716 individuals m(-3), with a dominance of copepods, mainly the calanoids Acartia lilljeborgii, Acartia tonsa and Pseudodiaptomus acutus. A clear seasonal pattern was observed: copepods were significantly more abundant during the rainy than in the dry season. Significant differences in abundance between the two bays were detected only for cirripede larvae, which were more abundant in Paranagua Bay. This lack of difference between the two areas was probably a consequence of the water circulation along the estuary, which may have diluted and dispersed the pollutants from Paranagua Bay to other areas of the estuary.

Gelatinous zooplankton fauna (Cnidaria, Ctenophora and Thaliacea) from Baia da Babitonga (southern Brazil)

The present study reports on a survey of the gelatinous zooplankton fauna (Cnidaria, Ctenophora and Thaliacea) from the proposed Baia da Babitonga marine protected area (southern Brazil; similar to 26 degrees S), based on collections from multiple sites over different seasons and from published literature. In order to sample both small and large gelatinous animals, plankton hauls (n = 255) and fishing trawls (n = 126) were employed. More than 20,000 organisms were studied, which, including literature data, totaled 48 species: one cubomedusa, three scyphomedusae, four siphonophores, 36 hydromedusae, two ctenophores, and two thaliaceans. Among these, the hydromedusae Cnidostoma fallax Vanhoffen and Helgicirrha sp. are recorded for the first time from the southwestern Atlantic coast and Paulinum sp. and Protiara sp. are recorded for the first time from the South Atlantic. A description of young stages of the hydromedusa Gossea brachymera Bigelow is presented and shows that Octobulbacea montehermosensis Zamponi is a junior synonym of the former. Although comprehensive local assessment of diverse taxonomic groups is still lacking, the high diversity observed herein underscores the importance of Ba a da Babitonga as a high priority site for conservation of regional marine biodiversity.

Mercury and Nitrogen Isotope in a Marine Species from a Tropical Coastal Food Web

The present study raised the hypothesis that the trophic status in a tropical coastal food web from southeastern Brazil can be measured by the relation between total mercury (THg) and nitrogen isotope (delta(15)N) in their components. The analysed species were grouped into six trophic positions: primary producer (phytoplankton), primary consumer (zooplankton), consumer 1 (omnivore shrimp), consumer 2 (pelagic carnivores represented by squid and fish species), consumer 3 (demersal carnivores represented by fish species) and consumer 4 (pelagic-demersal top carnivore represented by the fish Trichiurus lepturus). The values of THg, delta(15)N, and trophic level (TLv) increased significantly from primary producer toward top carnivore. Our data regarding trophic magnification (6.84) and biomagnification powers (0.25 for delta(15)N and 0.83 for TLv) indicated that Hg biomagnification throughout trophic positions is high in this tropical food web, which could be primarily related to the quality of the local water.

Feeding ecology of the American freshwater goby Ctenogobius shufeldti (Gobiidae, Perciformes) in a sub-tropical estuary

The feeding ecology of the American freshwater goby Ctenogobius shufeldti in a low salinity salt-marsh habitat in the Paranagua Bay estuarine complex (Brazil) was assessed through the gut analysis of 632 individuals. The effects of a set of abiotic factors (type of sediment, salinity, temperature and estuarine reach), season and body size on dietary composition were analysed. Seasonal and size-related changes in feeding strategy, feeding intensity and trophic level were assessed. The effects of gape and body size on prey size use were also analysed. The results showed that C. shufeldti is a typical omnivorous, generalized benthic predator of low trophic levels throughout the seasons and size classes, feeding on 56 dietary items; tanaids, chlorophyte algae, ostracods, gastropods, detritus and benthic diatoms made up the bulk of its diet. The tanaid Kalliapseudes schubarti was the main prey item in both numerical and volumetric terms. The gut fullness was persistently high across the seasons. As expected for a typical generalized, opportunistic omnivorous feeder: (1) seasonal and spatial-temporal variability of abiotic factors had a significant effect on diet structure, (2) season accounted for most of the dietary variation and (3) diet composition and the size of prey consumed did not vary across the size classes.

Evaluation of impacts of climate change and local stressors on the biotechnological potential of marine macroalgae: a brief theoretical discussion of likely scenarios

Climate change can be associated with variations in the frequency and intensity of extreme temperatures and precipitation events on the local and regional scales. Along coastal areas, flooding associated with increased occupation has seriously impacted products and services generated by marine life, in particular the biotechnological potential that macroalgae hold. Therefore, this paper analyzes the available information on the taxonomy, ecology and physiology of macroalgae and discusses the impacts of climate change and local stress on the biotechnological potential of Brazilian macroalgae. Based on data compiled from a series of floristic and ecological works, we note the disappearance in some Brazilian regions of major groups of biotechnological interest. In some cases, the introduction of exotic species has been documented, as well as expansion of the distribution range of economically important species. We also verify an increase in the similarities between the Brazilian phycogeographic provinces, although they still remain different. It is possible that these changes have resulted from the warming of South Atlantic water, as observed for its surface in southeastern Brazilian, mainly during the winter. However, unplanned urbanization of coastal areas can also produce similar biodiversity losses, which requires efforts to generate long-term temporal data on the composition, community structure and physiology of macroalgae.