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2.
J Fish Biol ; 91(6): 1642-1667, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29076535

RESUMO

A large fish-count dataset from the Brazilian province was used to describe spatial patterns in standing biomass and test if total biomass, taxonomic and functional trophic structure vary across nested spatial scales. Taxonomic and functional structure varied more among localities and sites than among regions. Total biomass was generally higher at oceanic islands and remote or protected localities along the coast. Lower level carnivores comprised a large part of the biomass at almost all localities (mean of 44%), zooplanktivores never attained more than 14% and omnivores were more representative of subtropical reefs and oceanic islands (up to 66% of total biomass). Small and large herbivores and detritivores varied greatly in their contribution to total biomass, with no clear geographical patterns. Macrocarnivores comprised less than 12% of the biomass anywhere, except for two remote localities. Top predators, such as sharks and very large groupers, were rare and restricted to a few reefs, suggesting that their ecological function might have already been lost in many Brazilian reefs.


Assuntos
Recifes de Corais , Peixes/fisiologia , Animais , Biodiversidade , Biomassa , Brasil , Comportamento Alimentar , Geografia , Ilhas , Dinâmica Populacional
3.
J Fish Biol ; 91(2): 558-573, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28703291

RESUMO

The damselfish Chromis limbata is native to the Macaronesian Archipelagos (Azores, Madeira and Canaries) and the western coast of Africa between Senegal and Angola. During the austral summers of 2008 and 2009 the species was recorded for the first time in the south-western Atlantic Ocean around Campeche and Xavier Islands, in Florianópolis, Santa Catarina State, Brazil. Here, the progression of C. limbata in southern Brazilian waters is described using visual counts and genetic surveys and changes in the density of the native congener Chromis multilineata were also investigated. Underwater visual censuses of both Chromis species were carried out from 2009 to 2014. Chromis limbata tissue samples were collected and the mtDNA control region was sequenced and compared with mtDNA haplotypes from the natural range to confirm species identity, compare genetic diversity and to infer connectivity between newly established Brazilian populations. The Brazilian population of C. limbata increased significantly over the past 5 years and the effect on C. multilineata is still an open question, longer time-series data will be necessary to clarify possible interactions. The molecular analyses confirmed species identity, revealed strong haplotype connectivity among Brazilian study sites and showed a low genetic diversity in Brazil when compared with the native populations, suggesting few individuals started the invasion. Four hypotheses could explain this colonizing event: C. limbata was released by aquarium fish keepers; larvae or juveniles were transported via ship ballast water; the species has rafted alongside oil rigs; they crossed the Atlantic Ocean through normal larval dispersal or naturally rafting alongside drifting objects. The rafting hypotheses are favoured, but all four possibilities are plausible and could have happened in combination.


Assuntos
Peixes/fisiologia , Espécies Introduzidas , Animais , Oceano Atlântico , Sequência de Bases , Brasil , DNA Mitocondrial/química , Peixes/genética , Variação Genética , Haplótipos , Filogenia , Densidade Demográfica
4.
Proc Biol Sci ; 283(1823)2016 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-26791611

RESUMO

Population ecology has classically focused on pairwise species interactions, hindering the description of general patterns and processes of population abundance at large spatial scales. Here we use the metabolic theory of ecology as a framework to formulate and test a model that yields predictions linking population density to the physiological constraints of body size and temperature on individual metabolism, and the ecological constraints of trophic structure and species richness on energy partitioning among species. Our model was tested by applying Bayesian quantile regression to a comprehensive reef-fish community database, from which we extracted density data for 5609 populations spread across 49 sites around the world. Our results indicate that population density declines markedly with increases in community species richness and that, after accounting for richness, energetic constraints are manifested most strongly for the most abundant species, which generally are of small body size and occupy lower trophic groups. Overall, our findings suggest that, at the global scale, factors associated with community species richness are the major drivers of variation in population density. Given that populations of species-rich tropical systems exhibit markedly lower maximum densities, they may be particularly susceptible to stochastic extinction.


Assuntos
Recifes de Corais , Metabolismo Energético/fisiologia , Peixes/fisiologia , Animais , Biodiversidade , Peixes/classificação , Modelos Biológicos , Densidade Demográfica
5.
PLoS One ; 10(6): e0127176, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26061735

RESUMO

The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most "pristine" areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contrasting tide pool habitats: open pools, which communicate with the open ocean even during low tides, thus more exposed to wave action; and closed pools, which remain isolated during low tide and are comparatively less exposed. Reef fish assemblages, benthic cover, algal turfs and fish feeding pressure on the benthos remarkably varied between open and closed pools. The planktivore Thalassoma noronhanum was the most abundant fish species in both habitats. In terms of biomass, the lemon shark Negaprion brevirostris and the omnivore Melichtys niger were dominant in open pools, while herbivorous fishes (mainly Acanthurus spp.) prevailed in closed pools. Overall benthic cover was dominated by algal turfs, composed of articulated calcareous algae in open pools and non-calcified algae in closed pools. Feeding pressure was dominated by acanthurids and was 10-fold lower in open pools than in closed pools. Besides different wave exposure conditions, such pattern could also be related to the presence of sharks in open pools, prompting herbivorous fish to feed more in closed pools. This might indirectly affect the structure of reef fish assemblages and benthic communities. The macroalgae Digenea simplex, which is uncommon in closed pools and abundant in the reef flat, was highly preferred in herbivory assays, indicating that herbivory by fishes might be shaping this distribution pattern. The variations in benthic and reef fish communities, and feeding pressure on the benthos between open and closed pools suggest that the dynamics in open pools is mostly driven by physical factors and the tolerance of organisms to harsh conditions, while in closed pools direct and indirect effects of species interactions also play an important role. Understanding the mechanisms shaping biological communities and how they scale-up to ecosystem functioning is particularly important on isolated near-pristine systems where natural processes can still be studied under limited human impact.


Assuntos
Recifes de Corais , Ecossistema , Comportamento Alimentar , Peixes/fisiologia , Animais , Oceano Atlântico , Brasil , Pressão
6.
Ecol Lett ; 17(9): 1067-76, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24943721

RESUMO

Fishes contribute substantially to energy and nutrient fluxes in reef ecosystems, but quantifying these roles is challenging. Here, we do so by synthesising a large compilation of fish metabolic-rate data with a comprehensive database on reef-fish community abundance and biomass. Individual-level analyses support predictions of Metabolic Theory after accounting for significant family-level variation, and indicate that some tropical reef fishes may already be experiencing thermal regimes at or near their temperature optima. Community-level analyses indicate that total estimated respiratory fluxes of reef-fish communities increase on average ~2-fold from 22 to 28 °C. Comparisons of estimated fluxes among trophic groups highlight striking differences in resource use by communities in different regions, perhaps partly reflecting distinct evolutionary histories, and support the hypothesis that piscivores receive substantial energy subsidies from outside reefs. Our study demonstrates one approach to synthesising individual- and community-level data to establish broad-scale trends in contributions of biota to ecosystem dynamics.


Assuntos
Ecossistema , Metabolismo Energético , Peixes/metabolismo , Modelos Biológicos , Animais , Biomassa , Densidade Demográfica
7.
Mol Phylogenet Evol ; 67(1): 1-8, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23277159

RESUMO

A molecular phylogeny of 15 (out of 26 recognized) species of Parablennius Miranda Ribeiro, 1915 was constructed based on two mitochondrial and two nuclear gene fragments, and using maximum parsimony, maximum likelihood and Bayesian approaches. The closely related genera Hypleurochilus, Salaria and Scartella were also studied to ascertain their relationship with Parablennius. Phylogenetic analyses were compared with morphology-based taxonomical studies. Hypleurochilus, Salaria and Scartella appear well supported within a clade including all Parablennius, indicating that this genus is paraphyletic. The species pairs P. parvicornis-P. sanguinolentus and P. gattorugine-P. ruber are well-supported and relatively distant from remaining Parablennius. Remaining Parablennius form two distinct well-supported groups: (1) a clade of Atlantic-Mediterranean Parablennius (P. pilicornis, P. marmoreus, P. rouxi, P. salensis and P. tentacularis); (2) a clade including Hypleurochilus, the Indo-Western Pacific Parablennius (P. cornutus, P. intermedius, P. tasmanianus and P. yatabei) and the Atlantic-Mediterranean P. incognitus and P. zvonimiri. Use of a relaxed molecular clock suggests that Indo-Pacific Parablennius originated recently from an Atlantic Parablennius that may have dispersed via southern Africa, rather than via the Tethys seaway.


Assuntos
Evolução Molecular , Perciformes/classificação , Filogenia , Distribuição Animal , Animais , Oceano Atlântico , Teorema de Bayes , Núcleo Celular/genética , DNA Mitocondrial/genética , Oceano Índico , Funções Verossimilhança , Modelos Genéticos , Perciformes/genética , Alinhamento de Sequência , Análise de Sequência de DNA
8.
J Fish Biol ; 81(5): 1773-80, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23020575

RESUMO

This study compared remote underwater video and traditional direct diver observations to assess reef fish feeding impact on benthos across multiple functional groups within different trophic categories (e.g. herbivores, zoobenthivores and omnivores) and in two distinct reef systems: a subtropical rocky reef and a tropical coral reef. The two techniques were roughly equivalent, both detecting the species with higher feeding impact and recording similar bite rates, suggesting that reef fish feeding behaviour at the study areas are not strongly affected by the diver's presence.


Assuntos
Comportamento Alimentar/fisiologia , Peixes/fisiologia , Biologia Marinha/métodos , Observação/métodos , Gravação em Vídeo , Animais , Biodiversidade , Densidade Demográfica
9.
J Fish Biol ; 80(4): 852-65, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22471804

RESUMO

In this study, cryptobenthic fish depth patterns and their correlations with habitat complexity and sea urchin densities were investigated. In general, total density, species richness and diversity were higher in the shallower zones (3 m), while evenness was higher at the 10 m depth zone. Among sites, species density was similar at the 10 m zone, but at the 3 m zone it varied greatly. Species-specific depth preferences were found. Correlation between species density and habitat complexity was usually positive. The influence of sea urchin densities on the cryptobenthic fish assemblage was site and species dependent.


Assuntos
Ecossistema , Peixes/fisiologia , Ouriços-do-Mar/fisiologia , Animais , Biodiversidade , Brasil , Densidade Demográfica
10.
Mol Phylogenet Evol ; 58(2): 409-13, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21185388

RESUMO

The Lusitania Province has been considered a transition zone between the Atlantic northern cold waters and Tropical warm waters. Tropical species have expanded their ranges during warm periods and either retreated during cold periods or survived in local refuges. Successive waves of dispersion into this Province could have favored diversification through geographic isolation. Taxa that remained in this large Province may also have diversified in loco. We analyzed molecular markers of the genus Microlipophrys (family Blenniidae) that confirm the validity of this genus and of the seven recognized species. Microlipophrys and its sister clade apparently originated within Lusitania and dispersed into the tropics at a later stage.


Assuntos
Evolução Molecular , Perciformes/classificação , Filogenia , Animais , Marcadores Genéticos , Geografia , Perciformes/genética , Análise de Sequência de DNA
11.
Rev Bras Biol ; 59(4): 567-75, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23505645

RESUMO

Patterns of richness and biogeography of Gastropoda molluscs were determined based on lists of species from five sites along the southwestern Atlantic. The analysis of the distribution patterns of these sites confirmed the existence of a broader transition zone between southern Espírito Santo State (21 degrees S) and Rio Grande do Sul State (32 degrees S). This zone is very heterogeneous, presenting a low endemism rate and a significant number of species common to the near provinces, and does not show enough consistency to be considered as an independent biogeographic province as proposed by Palacio (1980). Observing the distribution of species along the southwestern Atlantic we find an increase in the proportion of species with greatest latitudinal ranges (occurring from the tropics to Patagonia) from lowest to highest latitudes, following Rappoport's rule.


Assuntos
Gastrópodes , Animais , Oceano Atlântico , Biodiversidade , Brasil , Mapeamento Geográfico , Dinâmica Populacional , Especificidade da Espécie , Temperatura de Transição
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