Forest destructuring as revealed by the temporal dynamics of fundamental species - Case study of Santa Genebra Forest in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Quantitative and qualitative dynamics of exotic and native blowflies ( Diptera: Calliphoridae) with migrations among municipalities

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

Cerrado vegetation and global change: the role of functional types, resource availability and disturbance in regulating plant community responses to rising CO2 levels and climate warming

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Molecular diversity of fungal and bacterial communities in the marine sponge Dragmacidon reticulatum

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

ICHTHYOFAUNA IN AN ESTUARY OF THE MATARIPE AREA, TODOS OS SANTOS BAY, BAHIA, BRAZIL

The community structure and dynamics as well as some biological parameters of selected species of the ichthyofauna of the Mataripe estuarine region affected by the Landulfo Alves Oil Refinery (RLAM) were analyzed. Twenty stations were sampled with a gillnet in five different periods: August and December 2003, March and July/August 2004 and January 2005. Thirty-five actinopterygian species and one elasmobranch species were recorded, Oligoplites saurus, Diapterus rhombeus, Lutjanus synagris and Scomberomorus brasiliensis among them, on all the campaigns. A total of 1368 specimens, weighing 36.10 kg, were caught. The ichthyofauna total biomass was greater, in weight, on the eastern side of the study region, especially at the stations close to the shoals/reefs and the rocky bottom. A similar pattern was also observed for the diversity values. In general, low evenness and diversity were observed in the area studied, possibly as a result of the fishing gear used. D. rhombeus juveniles dominated in all but one of the samplings (July 2004), in which latter Cyclichthys spinosus was dominant. Carangids and species associated with consolidated bottoms were observed, although in small numbers, throughout the study period. In spite of the limitations imposed by the gear used for sampling, the estuarine area influenced by the RLAM was seen to play a role as a growth area for the great majority of species, especially the mojarra (D. rhombeus), but it offers no fishing potential due to the prevalence of young and small individuals. Evidence of imminent spawning was recorded for Pomadasys corvinaeformis in August 2003, and recent spawning in March 2004 for Oligoplites saurus. Further, mature individuals occurred in insufficient numbers to permit population level evaluation.

Estuarine and oceanic influences on copepod abundance and production of a subtropical coastal area

We investigated the influence of nutrient-rich oceanic waters in comparison to the estuarine outflow from Santos Bay (SE Brazil) on copepod abundance and production on the adjacent inner shelf. Zooplankton samples were collected with a Multinet in spring 2005 and in summer 2006. Copepod biomass was derived from length-weight regressions, and growth rates were estimated from empirical models. Altogether, 58 copepod taxa were identified. The highest abundances were due to small-sized organisms including nauplii, oncaeids and copepodids of paracalanids and clausocalanids. Biomass and secondary production mirrored copepod abundance, with Temora copepodids accompanying the above-mentioned taxa as major contributors. The contribution of naupliar biomass and production was low (2.2 and 3.8% of the total, respectively). The influence of the Santos Bay outflow was observed only in spring, when Coastal Water (CW) dominated at the study site; whereas in summer the inner shelf was occupied by CW in the surface layer and the oceanic South Atlantic Central Water (SACW) in the bottom layer. The SACW intrusion had more of an influence for the increase in copepod production than the Santos Bay plume. The distribution and dynamics of the oceanic water masses seemed to be the most important influence on copepod diversity and production at this subtropical site.

Bacterial and phytoplankton dynamics in a sub-tropical estuary

Heterotrophic bacterial and biomass, production, specific growth rates and growth efficiencies were studied in July 2001 and January 2002 during both spring and neap tides, along a tidal cycle, at three sites in a subtropical estuary. Major freshwater inputs located in the Northern region led to differences in both and bacterioplankton biomass and activity along the estuary. While in the Northern region is light-limited, with mean production (PP) between 1.1 and 1.9 mu g C l(-1) h(-1) and mean specific growth rates (PSG) between 0.14 and 0.16 d(-1), the Southern region registered values as high as 24.7 mu g C l(-1) h(-1) for PP and 2.45 d(-1) (mean PP between 3.4 and 7.3 mu g C l(-1) h(-1); mean PSG between 0.28 and 0.57 d(-1)). On the other hand, maximum bacterial production (BP: 63.8 mu g C l(-1) h(-1)) and specific growth rate (BSG: 32.26 d(-1)) were observed in the Northern region (mean BP between 3.4 and 12.8 mu g C l(-1) h(-1); mean BSG between 1.98 and 6.67 day(-1)). These bacterial activity rates are among the highest recorded rates in estuarine and coastal waters, indicating that this system can be highly heterotrophic, due to high loads of allochthonous carbon (mainly derived from mangrove forest). Our results also showed that, despite that BP rates usually exceeded PP, in the Southern region BP may be partially supported (similar to 45%) by PP, since a significant regression was observed between BP and PP (r = 0.455, P < 0.001).

Life cycle and reproductive traits of marine podonids (Cladocera, Onychopoda) in a coastal subtropical area

We studied the temporal distribution and reproductive biology of marine podonids during two consecutive years off Ubatuba, southeast coast of Brazil. Podonid specimens and their eggs and embryos were counted, measured and classified into categories. Pseudevadne tergestina was the most abundant species, and was more abundant in surface layers, in warm seasons, when the water column was stratified because of bottom intrusions of the cold and nutrient-rich South Atlantic Central Water (SACW) onto the inner shelf. Evadne spinifera had a similar temporal and vertical distribution, but with lower abundance and frequency. Pleopis schmackeri did not show a clear seasonal distribution, but preferred bottom layers. Pleopis polyphemoides and Podon intermedius occurred in low abundances, and only under SACW influence. Parthenogenetic females were dominant among all podonid species. Gamogenetic females of P. polyphemoides and P. intermedius were observed, but males of neither species occurred. This suggests that in tropical and subtropical regions, P. tergestina, E. spinifera and P. schmackeri reproduce through parthenogenesis during most of the year.

Reproductive migration and population dynamics of the blue crab Callinectes danae in an estuary in southeastern Brazil

Portunid crabs are an important resource in estuaries, and require appropriate management to guarantee their long-term availability. We investigated the population dynamics and reproduction of Callinectes danae in the Estuarine-Bay Complex of Sao Vicente, Sao Paulo, Brazil, to provide basic biological information for public policies for the management of this fishery. Monthly samples were obtained from March 2007 to February 2008 on eight transects, four in the estuary and four in the bay. A total of 2261 specimens (403 males, 1288 females, of which 570 were ovigerous) were collected. Males were significantly larger than females, and the size-frequency distribution was unimodal for males, females and ovigerous females. The sex ratio was nearly always skewed toward females (M:F - 1:4.6). C. danae showed seasonal-continuous reproduction, with high reproductive activity in the warmer season. C. danae breeds in the estuarine-bay complex, with males and juvenile females concentrated in the estuary. After copulation, fertilized females migrate to the estuary entrance and the bay, where ovigerous females are commonly found spawning in high-salinity areas. Therefore, to manage this important economic resource, both the estuary and the bay should be considered for protection, but special attention should be given to the estuary entrance during the summer months, when ovigerous females concentrate.

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 (>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.

INTERSPECIFIC VARIATION OF THE BACTERIAL COMMUNITY STRUCTURE IN THE PHYLLOSPHERE OF THE THREE MAJOR PLANT COMPONENTS OF MANGROVE FORESTS

Mangrove forests encompass a group of trees species that inhabit the intertidal zones, where soil is characterized by the high salinity and low availability of oxygen. The phyllosphere of these trees represent the habitat provided on the aboveground parts of plants, supporting in a global scale, a large and complex microbial community. The structure of phyllosphere communities reflects immigration, survival and growth of microbial colonizers, which is influenced by numerous environmental factors in addition to leaf physical and chemical properties. Here, a combination of culture-base methods with PCR-DGGE was applied to test whether local or plant specific factors shape the bacterial community of the phyllosphere from three plant species (Avicenia shaueriana, Laguncularia racemosa and Rhizophora mangle), found in two mangroves. The number of bacteria in the phyllosphere of these plants varied between 3.62 x 10(4) in A. schaeriana and 6.26 x 10(3) in R. mangle. The results obtained by PCR-DGGE and isolation approaches were congruent and demonstrated that each plant species harbor specific bacterial communities in their leaves surfaces. Moreover, the ordination of environmental factors (mangrove and plant species), by redundancy analysis (RDA), also indicated that the selection exerted by plant species is higher than mangrove location on bacterial communities at phyllosphere.

Pattern of distribution and environmental influences on the Scienidae community of the Southeastern Brazilian coast

The Sciaenids have among the highest species richness, numerical abundance and biomass of any family of fishes along the Brazilian coast. The aim of this study was to analyze the composition and spatial and temporal distribution of as well as the influence of temperature, salinity and depth on the sciaenid assemblage of Santos Bay. A total of 29,306 individuals belonging to 13 genera and 21 species were captured, between November 2004 and December 2005, with Stellifer rastrifer representing 70.4% of the total composition. Highest abundance and biomass occurred on the east side of the bay, and the highest species richness occurred near the mouth of the Santos Channel, which was also the site with least similarity to the other sites. Highest abundances occurred in April 2005 and lowest in September 2005. Key environmental factors influencing distribution of sciaenids were depth and temperature.

Population biology of Stellifer rastrifer, S. brasiliensis and S. stellifer in Caraguatatuba Bay, northern coast of São Paulo, Brazil

Ecosystems may reflect environmental changes in many respects, from the debilitation of individuals to alterations in community composition. Equally, population parameters may provide reliable indications of environmental changes. Members of the sciaenid fish genus Stellifer are usually very abundant where they occur, often with two or more species living in sympatry. Here, the population dynamics of three Stellifer species from southeastern Brazil were assessed. Sampling was carried out in shallow marine areas of Caraguatatuba Bay, from August 2003 to October 2004. The species evaluated were Stellifer rastrifer (n=3183), S. brasiliensis (n=357) and S. stellifer (n=116). The area under greater continental influence tended to support more, but smaller individuals. Size variations over time were similar among species and negatively correlated with Krel, which showed smooth fluctuations. The general length-frequency distribution was concentrated between 6.0 and 9.0 cm, and the great majority of females did not present mature gonads during the sampling period. The findings support the existence of a stratification by size for these species, indicating that the area is essential for the development of younger fish. Failure to consider these characteristics for the management of similar areas may have serious implications for these environments.

The Dynamics of a frictionally-dominated Amazonian estuary

The hydrodynamics, morphology and sedimentology of the Taperacu estuary were investigated. This is one of several estuaries located within the largest mangrove fringe in the world, bordering the Amazon region, subject to a macrotidal regime and regionally atypical negligible fresh water supply. The results reveal widespread sand banks that occupy the central portion of the estuarine cross-section. Well-sorted very fine sandy sediments of marine origin prevail. Shorter flood phases, with substantially higher current velocities, were observed in the upper sector of Taperacu, as expected for a shallow, friction-dominated estuary. However, ebb domination can be expected for estuaries with large associated mangrove areas and substantial estuarine infilling, both of which situations occur on the Taperacu. The tidal asymmetry favoring flood currents could be the result of the absence of an effective fluvial discharge. Furthermore, it was observed that the Taperacu is connected by tidal creeks to the neighboring Caete estuary, allowing a stronger flux during the flood and intensifying the higher flood currents. As a whole, the results have shown a complex interaction of morphological aspects (friction, fluvial drainage, connections with neighbor estuaries, infilling and large storage area) in determining hydrodynamic patterns, thus improving the understanding of Amazon estuaries.

Dynamics of phytoplankton associations in three reservoirs in northeastern Brazil assessed using Reynolds' theory

The aim of the present study was to evaluate the influence of seasonality on the behavior of phytoplankton associations in eutrophic reservoirs with different depths in northeastern Brazil. Five collections were carried out at each of the reservoirs at two depths (0.1 m and near the sediment) at three-month intervals in each season (dry and rainy). The phytoplankton samples were preserved in Lugol's solution and quantified under an inverted microscope for the determination of density values, which were subsequently converted to biomass values based on cellular biovolume and classified in phytoplankton associations. The following abiotic variables were analyzed: water temperature, dissolved oxygen, pH, turbidity, water transparency, total phosphorus, total dissolved phosphorus, orthophosphate and total nitrogen. The data were investigated using canonical correspondence analysis. The influence of seasonality on the dynamics of the phytoplankton community was lesser in the deeper reservoirs. Depth affected the behavior of the algal associations. Variation in light availability was a determinant of changes in the phytoplankton structure. Urosolenia and Anabaena associations were more abundant in shallow ecosystems with a larger eutrophic zone, whereas the Microcystis association was more related to deep ecosystems with adequate availability of nutrients. The distribution of Cyclotella, Geitlerinema, Planktothrix, Pseudanabaena and Cylindrospermopsis associations was different from that seen in subtropical regions and the substitution of these associations was related to a reduction in the eutrophic zone rather than the mixture zone. Published by Elsevier GmbH.