Thiony Simon

Fish Biodiversity of the Vitória-Trindade Seamount Chain, Southwestern Atlantic: An Updated Database

Despite a strong increase in research on seamounts and oceanic islands ecology and biogeography, many basic aspects of their biodiversity are still unknown. In the southwestern Atlantic, the Vitória-Trindade Seamount Chain (VTC) extends ca. 1,200 km offshore the Brazilian continental shelf, from the Vitória seamount to the oceanic islands of Trindade and Martin Vaz. For a long time, most of the biological information available regarded its islands. Our study presents and analyzes an extensive database on the VTC fish biodiversity, built on data compiled from literature and recent scientific expeditions that assessed both shallow to mesophotic environments. A total of 273 species were recorded, 211 of which occur on seamounts and 173 at the islands. New records for seamounts or islands include 191 reef fish species and 64 depth range extensions. The structure of fish assemblages was similar between islands and seamounts, not differing in species geographic distribution, trophic composition, or spawning strategies. Main differences were related to endemism, higher at the islands, and to the number of endangered species, higher at the seamounts. Since unregulated fishing activities are common in the region, and mining activities are expected to drastically increase in the near future (carbonates on seamount summits and metals on slopes), this unique biodiversity needs urgent attention and management.

Island biogeography of marine organisms

Studies on the distribution and evolution of organisms on oceanic islands have advanced towards a dynamic perspective, where terrestrial endemicity results from island geographical aspects and geological history intertwined with sea-level fluctuations. Diversification on these islands may follow neutral models, decreasing over time as niches are filled, or disequilibrium states and progression rules, where richness and endemism rise with the age of the archipelago owing to the splitting of ancestral lineages (cladogenesis). However, marine organisms have received comparatively little scientific attention. Therefore, island and seamount evolutionary processes in the aquatic environment remain unclear. Here we analyse the evolutionary history of reef fishes that are endemic to a volcanic ridge of seamounts and islands to understand their relations to island evolution and sea-level fluctuations. We also test how this evolutionary history fits island biogeography theory. We found that most endemic species have evolved recently (Pleistocene epoch), during a period of recurrent sea-level changes and intermittent connectivity caused by repeated aerial exposure of seamounts, a finding that is consistent with an ephemeral ecological speciation process. Similar to findings for terrestrial biodiversity, our data suggest that the marine speciation rate on islands is negatively correlated with immigration rate. However, because marine species disperse better than terrestrial species, most niches are filled by immigration: speciation increases with the random accumulation of species with low dispersal ability, with few opportunities for in situ cladogenesis and adaptive radiation. Moreover, we confirm that sea-level fluctuations and seamount location play a critical role in marine evolution, mainly by intermittently providing stepping stones for island colonization.

Target fishes on artificial reefs: evidences of impacts over nearby natural environments.

Topics in artificial reef research have included a wide number of themes but a major portion of published works are about the attraction that artificial reefs exert over fishes that reside in natural reefs. In the present work, underwater visual censuses of fishes were conducted at both artificial and natural reefs, aiming at verifying whether fishes are attracted or and produced on artificial reefs. Length frequency, mean biomass and frequency of occurrence of four fish genera targeted by local fisheries (Caranx, Haemulon, Lutjanus and Mycteroperca) were compared between two artificial and two natural reefs. Evidences of both production and attraction of target reef fishes by artificial reefs were found. Production is evidenced by the enormous abundance of recruits of a single grunt species, the tomtate (Haemulon aurolineatum Cuvier). The high concentration of adults of predator demersal fishes (Mycteroperca spp. and Lutjanus spp.), present at low density on natural reefs, is the main evidence for attraction by artificial reefs. Results are inconclusive for the pelagic predators Caranx spp. The attraction that artificial reefs exert over large demersal predators can negatively affect nearby natural areas through shifts in predation, competition or nutrient input. Production can affect benthic communities in soft bottoms adjacent to artificial reefs by foraging of reef-associated fishes. Even when unplanned for fisheries purposes artificial reefs are often submitted to commercial and recreational fisheries and, due to the strong attraction they exert over large predators, these structures need harvest regulations.

The shore fishes of the Trindade–Martin Vaz insular complex: an update

A compilation of historical and recent collections and observations of shore fishes yielded 154 recorded species for Trindade and 67 for Martin Vaz. Twelve taxa, mostly small cryptobenthic species with limited dispersal capabilities and low ecological amplitude, are endemic to this insular complex. In several cases, the seamounts of the Vitória-Trindade Chain appear to have acted as stepping stones between the mainland and islands in periods of low sea level.

Mesophotic fishes of the Abrolhos Shelf, the largest reef ecosystem in the South Atlantic.

Fishes inhabiting rhodolith beds and reefs at mesophotic depths on the Abrolhos Shelf, which encompasses the largest and richest coral reef formation in the South Atlantic Ocean, were assessed through technical diving and remotely operated vehicles (ROVs). A total of 74 fish species were recorded, including at least one new species, one new record for the south-western Atlantic and six new records for the Abrolhos region. Overfishing, mining and port activities are already threatening many endangered and commercially important species recorded on the mesophotic reefs of Abrolhos Shelf, and the establishment of marine protected areas and off-reserve fisheries regulations are urgently needed.

First record of partial melanism in the coney Cephalopholis fulva (Perciformes: Epinephelidae)

raphaelmacieira@hotmail.com Many abnormalities in the coloration of fishes have been recorded, including albinism, melanism and ambicoloration (e.g . DAHLBERG, 1970). Melanism, according to Gould and Pyle (1896), is characterized by the presence of an excessive amount of pigment in tissues and skin. In fishes, melanism may occur in varying degrees of intensity (PIGG, 1998) and can, in some cases, result from injury (DAHLBERG, 1970), genetic inheritance (HORTH, 2006), intergeneric hybridization (ELWIN, 1957) or parasite infestation (HSIAO, 1941). The coney Cephalopholis fulva (Linnaeus, 1758) is distributed in the Western Atlantic from South Carolina, USA, to Southeastern Brazil (FIGUEIREDO; MENEZES, 1980). As its Northwestern Atlantic and Caribbean counterparts, the Brazilian coney presents three color phases. The red phase is found in deep water individuals, the uniformly brown or bicolored phase (in which the upper half of the body is dark brown and the lower half creamy white) is mostly encountered in shallow water individuals and the xanthic phase (actually a morph rather than a phase) is found independently of depth (SMITH, 1971). This author suspected that the yellow variety is actually the result of a single gene, but no further information exists on this subject. The species exhibits diel changes in the pattern of coloration and the alternation between the fully brown pattern in daytime and the bicolored pattern at night has been fully documented (NEMTZOV et al., 1993). This present study describes the first recorded occurrence (DAWSON, 1964, 1966, 1971) of partial melanism in the coney. The specimen was captured about 10 km off the coast of Guarapari, Espirito Santo, Southeastern Brazil, near Rasas and Escalvada islands (20o42’07,8”S e 40o23’36,8”W), during hook and line samplings undertaken at quarterly intervals between July 2005 and October 2007. The substrate is formed of a mosaic of calcareous algae beds, rocky and biogenic reefs and extensive deposits of unconsolidated sediments, at depths varying from 15 to 33 m. An additional 147 coneys were captured during sampling. None, however, presented any type of coloration abnormality. The frequency of occurrence of the anomaly was therefore estimated to be 0.68 %. The specimen was photographed still fresh (Fig. 1a) and maintained frozen until fixation in 10 % formaldehyde and preservation in 70 % ethanol. The area of the melanic part of the body was estimated from a digital photography of the right side of the fish (Fig. 1a). A 1300-square grid was digitally overlaid onto the photography to determine the proportion of squares over melanic skin. As both sides displayed the some pattern and extent of melanosis, there was no need for measuring the area on the left side, and the result obtained for the right side was extrapolated for the whole body. The specimen is deposited in the fish collection of the Universidade Federal do Espirito Santo (CIUFES 0219). The anomalous specimen is an individual of medium size (223 mm total length; 186 mm standard length) and apparently healthy. The melanic portion is restricted to the posterior half of the body, beginning at a vertical under the last spine of the dorsal fin and extending to the end of the tail. This corresponds to 37.7 % of the corporal surface area (fins included). The excess of melanin was limited to the epidermis over the posterior extremity of body scales and over the whole scales and naked skin on the fins. The intensity of the pigmentation of the melanic area is greater on the dorsal and caudal fins, merging into a blander tonality in the lateral region of the body. The two small black spots on the top of the caudal peduncle, usual in this species (HEEMSTRA; RANDALL, 1993), cannot be seen due to the strong pigmentation in this region. The remainder of the body displays the normal coloration of an individual in the red phase (HEEMSTRA; RANDALL, 1993). In particular, the small dark-edged pale blue spots over the whole body (observed in the fresh organism (Fig. 1a) but that turned entirely dark after fixation (Fig. 1b) and the two small black spots on the tip of the lower jaw (one on each side), characteristic of the species, are present.

Are melanic coney Cephalopholis fulva getting common

Here we report the second and third known specimens of Cephalopholis fulva with partial melanic coloration, photographed at Fernando de Noronha Archipelago and Camamu Bay, south-western Atlantic. While the species exhibits a wide range of colorations, the melanic pattern is an aberration only recently reported. Since C. fulva is common within its area of distribution and is of importance to fisheries, increasing records of melanism can either result from higher frequency than previously thought or, alternatively, that this condition is becoming more common.