Testing the ecomorphological hypothesis in a headwater riffles fish assemblage of the rio São Francisco, southeastern Brazil

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

Seasonal diet shifts of seven fish species in an Atlantic rainforest stream in Southeastern Brazil

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

Phenotypic changes and small mammal impoverishment on a Brazilian Atlantic Forest Island

Faunal impoverishment and distorted species compositions are common phenomena in oceanic islands; however, many land-bridge islands are poorly inventoried, especially in the Neotropics. We sampled a small mammal community on a land-bridge island (Anchieta Island) along the Brazilian coast. We found only one marsupial Didelphis aurita (Wied-Neuwied, 1826) and two rodent species Oligoryzomys nigripes (Olfers, 1818) and Trinomys iheringi (Thomas, 1911) during 12 months of live trapping and 9195 trap-nights. The diversity of rodents and marsupials was not explained by species-area relations, indicating possible past extinctions. The abundance of D. aurita and O. nigripes was approximately three times higher, while the abundance of T. iheringi was approximately four times lower than abundances reported from other Brazilian Atlantic Forest sites. The population of D. aurita exhibited many phenotypic changes; males were on average 8 % smaller and females produced 30 % less litters than those from the mainland and other land-bridge islands. The long history of forest disturbance, habitat loss, reduction in forest productivity, and the recent introduction of mesopredators may be the major drivers that explain the small mammal community composition on this island. © 2013 Walter de Gruyter GmbH, Berlin/Boston.

Ictiofauna do Córrego Rico, bacia do rio Mogi Guaçu, alto Paraná

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Composition of functional ecological guilds of the fish fauna of the internal sector of the Amazon Estuary, Pará, Brazil

O presente estudo descreve a estrutura espacial e temporal da comunidade de peixes estuarinos da porção interna do estuário Amazônico. Amostras foram obtidas no canal principal e canais de maré das Baías do Guajará e Marajó e rio Guamá. Foram coletados um total de 41.516 espécimes, correspondendo 136 espécies, 38 famílias e 12 ordens. Na estação seca, a salinidade média no canal principal aumentou ao longo do gradiente limnico–marinho, entre o rio Guamá e a Baía do Marajó. A riqueza de espécies foi mais baixa na foz do rio Guamá e na margem direita da baía do Guajará. A composição das espécies e as guildas ambientais diferiram significativamente entre as áreas: Migrantes e Ocasionais de água doce foram dominantes no rio Guamá e na Baía do Guajará, enquanto Estuarinas, Marinhas Migrantes e Ocasionais dominaram na Baía do Marajó. Contudo, as guildas tróficas foram relativamente bem balanceadas, em termos funcionais. Piscívoros e Zoobentívoros foram os grupos alimentares dominantes em todas as áreas. Neste estudo, a avaliação da comunidade e o uso da abordagem com guildas foram eficientes para descrever a estrutura e o funcionamento das assembleias de peixes estuarinos e também como ferramenta na avaliação das pressões antrópicas na área.

Caracterização da ictiofauna da represa de Barra Bonita (SP) e adaptação do índice de integridade biótica (IIB)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Disentangling the influences of habitat structure and limnological predictors on stream fish communities of a coastal basin, southeastern Brazil

Em ambientes de riacho, fatores relacionados à estrutura dos habitats e limnologia interagem regulando os padrões de transferência de energia e matéria, afetando a composição da comunidade de peixes. Em bacias costeiras do sudeste do Brasil as características limnológicas e estrutura dos habitats diferem entre riachos de águas claras e pretas. Os primeiros são compostos por uma variedade de tipos de substrato, possuem velocidades de corrente mais elevadas e baixa condutividade, enquanto os últimos apresentam substrato arenoso, baixas velocidades de corrente e águas escuras e ácidas. Neste trabalho analisamos a importância relativa da estrutura dos habitats e das variáveis limnológicas como preditores dos padrões de composição em comunidades de peixes de riachos. Oito riachos de primeira a terceira ordem foram amostrados na planície costeira da bacia do rio Itanhaém. Capturamos 34 espécies e verificamos que a composição das comunidades foi influenciada por fatores estruturais e limnológicos, sendo os primeiros mais importantes. Uma fração de variação que não pode ser totalmente decomposta, deve-se à influência conjunta da limnologia e estrutura dos habitats. Algumas das espécies restritas aos riachos de águas pretas provavelmente apresentam adaptações fisiológicas e comportamentais para lidar com os baixos níveis de pH. Quando foram examinados somente os riachos de águas claras, toda a variação explicada na composição da comunidade de peixes foi atribuída aos fatores estruturais, devido a preferências específicas por diferentes características de hábitats.

Spatiotemporal variation in life history traits of three small fishes in streams of south-eastern Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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.

ICHTHYOPLANKTON DISTRIBUTION AND ABUNDANCE IN THE NORTHERN TODOS OS SANTOS AND CAMAMU BAYS, BAHIA STATE - BRAZIL

The occurrence, distribution and abundance of ichthyoplankton in Todos os Santos and Camamu Bays were analyzed based on four samplings (winter 2003, summer 2003, winter 2004 and summer 2005). Samples were obtained by surface horizontal hauls, using a 200-mu m mesh conical-cylinder plankton net. The distribution and abundance of eggs indicate a remarkable seasonal and annual variation of spawning activity in the region, especially when the two summer campaigns are compared. In summer 2003 the highest quantitative values were recorded, especially for Camamu, where the maximum reached 106.56 eggs.m(-3), with an overall average of 43.46 eggs.m(-3) for the two areas. In summer 2005 values were relatively low, the overall average being 3.49 eggs.m(-3). The larval taxonomic composition is characterized by the predominance of gobiids, with small variation from summer to winter. Considering all the campaigns and samplings undertaken in both areas, larvae of 11 families were identified: Engraulidae, Clupeidae, Mugilidae, Atherinopsidae, Hemiramphidae, Syngnathidae, Blenniidae, Carangidae, Gobiidae, Achiridae and Tetraodontidae.

Evaluating gillnetting protocols to characterize lacustrine fish communities

Ecological research and monitoring of lacustrine ecosystems often requires a whole-lake assessment of fish communities. Gillnet sampling offers an efficient means of estimating abundance, biomass and fish community composition. However the choice of gillnet sampling protocol may influence lake characterization via physical properties of the nets and allocation of sampling effort between littoral, benthic and pelagic habitats. This paper compares two commonly used, whole-lake sampling protocols applied across 17 prealpine, subalpine and alpine European lakes ranging widely in size, depth and altitude to determine their relative strength for research and management applications. Effort-corrected estimates of abundance, biomass and species richness were correlated between the protocols and both distinguished the trout-dominated alpine communities from subalpine and prealpine lakes dominated by whitefish and perch. A considerable amount of variance remained unexplained between the two protocols however, which seemed to correspond with differences in the proportion of effort among benthic and pelagic habitats. We suggest that both the European standard (CEN) and vertical (VERT) netting protocols are suitable for assessing ecological status and monitoring changes in lake fish communities through time. However the details of each protocol should be kept in mind when comparing fish communities between lakes. Mesh sizes used in CEN nets produce a more even size frequency distribution, suggesting that this protocol is most appropriate for assessing size structure of fish assemblages. The high proportion of netting effort in benthic habitats shallower than 70 m depth under the CEN protocol means that, particularly in larger lakes, outcomes will be disproportionately influenced by the ecological condition of this habitat. The VERT protocol presumably provides a more accurate estimate of whole-lake CPUE and community composition because effort, in terms of net area, is more evenly distributed across the entire volume of the lake. This is particularly important in large and deep lakes where pelagic habitats occupy a high proportion of the lake volume.

Estimating whole-lake fish catch per unit effort

The European standard for gillnetsampling to characterize lake fish communities stratifies sampling effort (i.e., number of nets) within depth strata. Nets to sample benthic habitats are randomly distributed throughout the lake within each depth strata. Pelagic nets are also stratified by depth, but are set only at the deepest point of the lake. Multiple authors have suggested that this design under-represents pelagic habitats, resulting in estimates of whole-lake CPUE and community composition which are disproportionately influenced by ecological conditions of littoral and benthic habitats. To address this issue, researchers have proposed estimating whole-lake CPUE by weighting the catch rate in each depth-compartment by the proportion of the volume of the lake contributed by the compartment. Our study aimed to assess the effectiveness of volume-weighting by applying it to fish communities sampled according to the European standard (CEN), and by a second whole-lake gillnetting protocol (VERT), which prescribes additional fishing effort in pelagic habitats. We assume that convergence between the protocols indicates that volume-weighting provides a more accurate estimate of whole-lake catch rate and community composition. Our results indicate that volume-weighting improves agreement between the protocols for whole-lake total CPUE, estimated proportion of perch and roach and the overall fish community composition. Discrepancies between the protocols remaining after volume-weighting maybe because sampling under the CEN protocol overlooks horizontal variation in pelagic fish communities. Analyses based on multiple pelagic-set VERT nets identified gradients in the density and biomass of pelagic fish communities in almost half the lakes that corresponded with the depth of water at net-setting location and distance along the length of a lake. Additional CEN pelagic sampling effort allocated across water depths and distributed throughout the lake would therefore help to reconcile differences between the sampling protocols and, in combination with volume-weighting, converge on a more accurate estimate of whole-lake fish communities.

(Table 1) Depth and time of first appearance of species identified by fish remains in ODP Site 169-1034

Ocean Drilling Program Leg 169S retrieved a complete Holocene sequence from Saanich Inlet, British Columbia, Canada. Fish and diatom remains were extracted from sediments at Site 1034. Very small fish bones, teeth and scales were ubiquitous except in the lowermost glaciomarine clays; scales degraded with depth. In the identifiable fraction, Pacific herring were the most abundant with Pacific hake and cartilaginous fish yielding significant fractions. Fish remains appear just before 12 000 BP but greatest diversity does not occur until about 6500 BP. A smoothed abundance curve highlights two periods of maximal abundance at about 1500 and 6500 BP. Abundances in the last 1000 years are lower than the rest of the record. A correlation with abundances of seven phytoplankton taxa is significant; diatoms explain about a third of the variance. This study demonstrates the use of fish and diatoms from the same paleosedimentary matrix to examine millennia-scale correlations between primary and tertiary production.

Crustaceans and fish abundances and species at and around artificially introduced tetrapod fields in the southern North Sea, 2010-2011

In the coming decades, artificial defence structures will increase in importance worldwide for the protection of coasts against the impacts of global warming. However, the ecological effects of such structures on the natural surroundings remain unclear. We investigated the impact of experimentally introduced tetrapod fields on the demersal fish community in a hard-bottom area in the southern North Sea. The results indicated a significant decrease in fish abundance in the surrounding area caused by migration effects towards the artificial structures. Diversity (HB) and evenness (E) values exhibited greater variation after the introduction of the tetrapods. Additionally, a distinct increase in young-of-the-year (YOY) fish was observed near the structures within the second year after introduction. We suggest that the availability of adequate refuges in combination with additional food resources provided by the artificial structures has a highly species-specific attraction effect. However, these findings also demonstrate that our knowledge regarding the impact of artificial structures on temperate fish communities is still too limited to truly understand the ecological processes that are initiated by the introduction of artificial structures. Long-term investigations and additional experimental in situ work worldwide will be indispensable for a full understanding of the mechanisms by which coastal defence structures interact with the coastal environment.

Physicochemical properties and fish occurrence in 35 Icelandic lakes housing Arctic charr (Salvelinus alpinus)

The common occurrence of parallel phenotypic patterns suggests that a strong relationship exists between ecological dynamics and micro-evolution. Comparative studies from a large number of populations under varying sets of ecological drivers could contribute to a better understanding of this relationship. We used data on morphology of arctic charr (Salvelinus alpinus) and ecological factors from 35 Icelandic lakes to test the hypothesis that morphological patterns among monomorphic charr populations from different lakes are related to interlake variation in ecological characteristics. There is extensive phenotypic diversity among populations of Icelandic charr, and populations are easily distinguished based on overall body morphology. The results obtained in the present study showed that the morphological diversity of charr was related to large-scale diversity in lake ecology. Variation in charr morphology was related to water origin (e.g. spring fed versus run-off), bedrock age, and fish community structure. The present study shows how various ecological factors can shape the biological diversity that we observe.