scholarly journals Dynamics of fish assemblages on a continuous rocky reef and adjacent unconsolidated habitats at Fernando de Noronha Archipelago, tropical western Atlantic

2011 ◽  
Vol 9 (4) ◽  
pp. 869-879 ◽  
Author(s):  
Paulo R. Medeiros ◽  
Ricardo S. Rosa ◽  
Ronaldo B. Francini-Filho

In recent years, many studies investigated how density-dependent factors, such as shortages in microhabitat and food availability influence the structure of reef fish assemblages. Most of what is currently known, however, comes from comparisons of isolated patch reefs and from correlations between fish abundance and one or few microhabitat variables. In addition, most studies were done in the Caribbean and Indo-Pacific regions, whereas the South Atlantic region has been, to date, understudied. The present study evaluated spatial and temporal variations in reef fish abundance and species richness in a continuous rocky reef and adjacent unconsolidated habitats in a Southwestern Atlantic reef, using underwater techniques to assess both fish numbers and microhabitat variables (depth, rugosity, number of crevices and percent cover of live benthic organisms, bare rock, sand, and limestone). Higher species richness was observed at consolidated substratum stations on both sampling periods (May and October), but fish abundance did not show a significant spatial variation. Topographical complexity and percent cover of algae (except coralline algae) were amongst the most important determinants of species richness, and correlations between fish size and refuge crevice size were observed. The non-random patterns of spatial variation in species richness, and to a lesser extent, fish abundance, were related to differences in substratum characteristics and the inherent characteristics of fishes (i.e. habitat preferences) and not to geographical barriers restraining fish movement. This study highlights the importance of concomitantly assessing several microhabitat variables to determine their relative influence in reef fish assemblages.

2011 ◽  
Vol 59 (3) ◽  
pp. 201-212 ◽  
Author(s):  
Guilherme Henrique Pereira-Filho ◽  
Gilberto Menezes Amado-Filho ◽  
Silvia M. P. B. Guimarães ◽  
Rodrigo L. Moura ◽  
Paulo Y. G. Sumida ◽  
...  

The Trindade and Martin Vaz island group (TMVIG) is located at about 1,120 km off the Brazilian coast. Despite its importance, highlighted by the presence of several endemic fish species, the TMVIG lacks detailed information on the structure of fish and benthic assemblages. Presented here is the first quantitative assessment of reef fish and benthic assemblages of the TMVIG in a depth gradient ranging from 5 to 45 m. Additional qualitative information on reef assemblages between 45 and 100 m was obtained using advanced gas diving techniques (TRIMIX) and a remotely operated vehicle (ROV). Similarly to other Brazilian oceanic islands, the TMVIG possesses depauperated fish and benthic assemblages, possibly due to its isolation and small size in comparison to the mainland. Depth was the most important factor affecting the structure of fish assemblages, with the density of most fish species declining with depth. Deep reefs (> 45 m) were characterized by the presence of extensive rhodolith beds and rocky reefs sparsely covered with crustose coralline algae, black coral (Cirripathes sp.) and a few massive or plate-like reef corals. Part-time or obligatory planktivorous fishes (e.g. Cephalopholis furcifer and Clepticus brasiliensis) also dominated deep reefs. Similar characteristics were recorded in mesophotic reef ecosystems across the Western Atlantic. Evidence of overfishing (obtained here and in other recent studies), the presence of four endemic and restricted range fish species, as well as the increase in number of new (and still undescribed) endemic taxa, indicates that the adoption of precautionary conservation measures are urgently needed in order to maintain the fragile and unique ecosystems of the TMVIG.


2006 ◽  
Vol 63 (5) ◽  
pp. 775-784 ◽  
Author(s):  
Dan Wilhelmsson ◽  
Torleif Malm ◽  
Marcus C. Öhman

Abstract A significant expansion of offshore windpower is expected in northwestern Europe in the near future. Little is known about the impacts it may have on the marine environment. Here, we investigate the potential for wind turbines to function as artificial reefs and fish aggregation devices (FADs), i.e. whether they would locally increase fish densities or alter fish assemblages. Fish communities and habitat composition were investigated using visual transects at two windpower farms off the southeastern coast of Sweden, central Baltic Sea. Fish abundance was greater in the vicinity of the turbines than in surrounding areas, while species richness and Shannon–Wiener diversity (H′) were similar. On the monopiles of the turbines, fish community structure was different, and total fish abundance was greater, while species richness and diversity (H′) were lower than on the surrounding seabed. Blue mussels and barnacles covered most of the submerged parts of the turbines. On the seabed, more blue mussels and a lesser cover of red algae were recorded around the power plants than elsewhere. Results from this study suggest that offshore windfarms may function as combined artificial reefs and fish aggregation devices for small demersal fish.


2004 ◽  
Vol 144 (1) ◽  
pp. 161-182 ◽  
Author(s):  
J. A. Garc�a-Charton ◽  
�. P�rez-Ruzafa ◽  
P. S�nchez-Jerez ◽  
J. T. Bayle-Sempere ◽  
O. Re�ones ◽  
...  

Author(s):  
Laís de Carvalho Teixeira Chaves ◽  
Cassiano Monteiro-Neto

Reef fish community structures at three sites in the state of Rio de Janeiro (Pedra Vermelha (PV), Cabo Frio Island—Arraial do Cabo; Mãe Island (MI), Itaipu—Niterói; Comprida Island (CI), Cagarras Archipelago—Rio de Janeiro) were investigated to assess differences in fish species composition, density and distribution of trophic groups, between sites, correlating the observed patterns of fish distribution with environmental factors. Thirty-six visual strip-transects yielded 67 species of 34 families. Studied locations shared at least 40% of all species, mostly of western Atlantic distribution. The three sites presented significant differences on diversity, density and species dominance. CI presented the highest values, except for total density, which was higher at PV, probably due to its partial degree of protection. MI showed the lowest values, suggesting possible impacts from the proximity to the shore. The main trophic categories were omnivores followed by mobile invertebrate feeders, in similarity to what was previously observed for south-eastern Brazil. Inherent habitat features of each location regarding depth, declivity, visibility and rugosity resulted in different species distribution and dominance patterns.


2018 ◽  
Vol 69 (4) ◽  
pp. 525 ◽  
Author(s):  
Pablo Pita ◽  
Diana Fernández-Márquez ◽  
Juan Freire

Temperate rocky reefs and kelp forest ecosystems have been severely affected by overfishing, pollution and habitat destruction, and climate change is a major driver of kelp decline in many regions. Although necessary for management, ecological interactions between kelp and fish remain largely unknown in the north-east Atlantic. In the present study, underwater visual censuses (UVC) and univariate and multivariate multiple regression models were used to analyse the spatiotemporal variations in the abundance and habitat use of the rocky reef fish and macroalgae assemblages of Galicia (north-west Spain). The underwater seascape was dominated by large rocks and kelp forests of Laminaria hyperborea, L. ochroleuca and Saccorhiza polyschides. Fish assemblages were ruled by gadids, labrids and sparids. The most frequent fish species were Labrus bergylta (counted in 90% of UVC) and Pollachius pollachius (in 100% of UVC), whereas the most abundant were Boops boops (mean±s.d., 556.4±39.7 individuals ha–1) and L. bergylta (432.10±440.05 individuals ha–1). Fish and macroalgal assemblages showed different spatial preferences and responded strongly to seasonality, wave exposure and depth. To a lesser degree, fish and macroalgal assemblages showed preferences for habitat structure. Moreover, because the findings of the present study indicate that L. bergylta is a good indicator species of the health of rocky reef and kelp forests ecosystems, monitoring of this fish can be helpful for management and conservation actions.


2015 ◽  
Vol 48 (2) ◽  
pp. 481-493 ◽  
Author(s):  
Leonardo Lara de Carvalho ◽  
Eduardo Godoy Aires de Souza ◽  
Mauricio Roque da Mata Júnior ◽  
Roberto Campos Villaça

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jonathan S. Lefcheck ◽  
Graham J. Edgar ◽  
Rick D. Stuart-Smith ◽  
Amanda E. Bates ◽  
Conor Waldock ◽  
...  

AbstractChanging biodiversity alters ecosystem functioning in nature, but the degree to which this relationship depends on the taxonomic identities rather than the number of species remains untested at broad scales. Here, we partition the effects of declining species richness and changing community composition on fish community biomass across >3000 coral and rocky reef sites globally. We find that high biodiversity is 5.7x more important in maximizing biomass than the remaining influence of other ecological and environmental factors. Differences in fish community biomass across space are equally driven by both reductions in the total number of species and the disproportionate loss of larger-than-average species, which is exacerbated at sites impacted by humans. Our results confirm that sustaining biomass and associated ecosystem functions requires protecting diversity, most importantly of multiple large-bodied species in areas subject to strong human influences.


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