Abstract: How do biogeographically different provinces arise in response to oceanic barriers to dispersal? Here we analyse how traits related to the pelagic dispersal and adult biology of 985 tropical reef-fish species correlate with their establishing populations on both sides of two Atlantic marine barriers: the Mid-Atlantic Barrier and the Amazon-Orinoco Plume. Generalized linear mixed-effects models indicate that predictors for successful barrier-crossing are the ability to raft with flotsam for the deep-water Mid-Atlantic Barrier, non-reef habitat usage for the freshwater and sediment-rich Amazon-Orinoco Plume, and large adult-size and large latitudinal-range for both barriers. Variation in larval-development mode, often thought to be broadly related to larval-dispersal potential, is not a significant predictor in either case. Many more species of greater taxonomic diversity cross the Amazon-Orinoco Plume than the Mid-Atlantic Barrier. Rafters readily cross both barriers but represent a much smaller proportion of Amazon-Orinoco Plume crossers than Mid-Atlantic Barrier crossers. Successful establishment after crossing both barriers may be facilitated by broad environmental tolerance associated with large body-size and wide latitudinal-range. These results highlight the need to look beyond larval dispersal potential and assess adult-biology traits when assessing determinants of successful movements across marine barriers.
Abstract: Detecting and determining the validity of local extinctions is an important conservation measure in order to uncover management failures. There are quantitative and qualitative methods that estimate extinction probability based on past sighting records. However, because current baselines about speciesâ abundances and distributions in the sea were mostly established after humans had started affecting marine populations, researchers must often rely on historical data to elucidate past environmental conditions. We review early historical records from the Archipelago of Saint Paulâs Rocks, together with data from recent expeditions, with the aim of testing the hypothesis that reef sharks (Carcharhinus spp.) have become extinct there. Our analyses are based on non-parametric probabilistic tests for extinction and on a qualitative framework to examine and judge as objectively as possible the likelihood of local extinction. Until the mid-twentieth century, visitors to St. Paulâs Rocks invariably commented on the remarkable number of sharks around the Archipelago. These observations contrast with those of expeditions carried out during the last decade, which report no carcharhinid reef sharks while scuba diving in the archipelago, despite many more hours of underwater fieldwork than previous expeditions. All quantitative and qualitative methods conclude that the reef shark Carcharhinus galapagensis is locally extinct at St. Paulâs Rocks after a sharp decrease in abundance that took place following the commencement of fishing. However, the persistence of occasional individuals of the once locally common C. falciformis in the vicinity of the Archipelago, as a result of constant immigration of this oceanic species from outside the area, suggest that the population might recover if the present fishing pressure was removed.
Abstract: The reproductive strategies of surgeonfishes of the genus Acanthurus are well known for all Atlantic species except the Monrovia doctorfish, Acanthurus monroviae, an eastern Atlantic surgeonfish whose biology remains largely unknown. We provide here the first account on the spawning behavior of A. monroviae, an exotic fish on rocky reefs of southeastern Brazilian coast.
Abstract: Halichoeres sazimai, n. sp. is described from the Western South Atlantic. During many years it was misidentified as H. bathyphilus from the Northwestern Atlantic, but it can be distinguished from the latter by striking color differences between the two species, with H. sazimai being characterized by a white body with a midline, zigzag patterned stripe on body, black and brownish in terminal males and yellow or golden in females and juveniles. Preserved specimens can also be distinguished by the visible mid-body stripe in H. sazimai, which disappears in H. bathyphilus. Diagnostic differences in the mitochondrial DNA cytochrome b gene separate H. sazimai from all other Western Atlantic labrids, with H. bathyphilus being its sister species. Individuals of H. sazimai were observed living on the deeper parts (20-40 m) of rocky reefs and sand bottoms, apparently associated with water temperatures lower than 18°C. This species is currently known from the southeastern and southern coasts of Brazil, from EspÃrito Santo to Santa Catarina States
Abstract: An analysis of 79 underwater photographs of Manta birostris gathered over a period of nine years in a marine protected area in southeastern Brazil suggests a high predictability of manta ray occurrences in the region during the austral winter (JuneâSeptember). The reasons for this are probably related to the seasonal oceanographic conditions, as characterized by the presence of a coastal front at the study site in winter and consequent plankton enrichment, which provides a feeding opportunity for manta rays. In addition, a melanistic individual in the Atlantic Ocean that is similar in color to the Pacific Oceanâs âblack mantaâ is reported for the first time.
Abstract: An unidentified species of hermit crab from the Maldives was photographed using a plastic box as shelter instead of a natural shell. This could be a result of increased pollution and shell collection disrupting the natural processes in coral reefs.
Abstract: An unusual colour morph of a probable Holacanthus ciliaris was observed in Dry Tortugas, Florida, which can possibly be explained by recessive homozygosity, however, further testing is necessary. This variation of H. ciliaris has previously only been described at St Paul's Rocks, Mid-Atlantic Ridge.
Abstract: A check-list containing 196 species of reef fishes recorded at the Laje de Santos Marine State Park is presented. Most of them occur along the tropical western Atlantic or occur on both sides of the Atlantic Ocean. A minor part ranges to the temperate rocky reefs of Patagonia or are endemics to southeastern Brazil. Moringua edwardsi, Antennarius multiocellatus, Scorpaena dispar, Aulostomus strigosus, Lutjanus buccanella, Mulloidichthys martinicus and Halichoeres penroseihave here their ranges extended southwards to the São Paulo coast. Basic data on species abundance at the study site, distribution of species between habitat types, trophic structure, feeding symbiotic associations, and conservation are commented
upon.
Abstract: After c. 30 years without sighting or capture, Anthias salmopunctatus was rediscovered at the type locality, St Peter and St Paul's Rocks, Mid-Atlantic Ridge. To date, the known distribution is restricted to depths varying from 35 to 55 m in vertical drop offs around the perimeter of the islands (c. 400 m). This may be the smallest geographic range known for a marine fish species
Abstract: The presence of 'vagrants' of the eastern Atlantic surgeonfish Acanthurus monroviae is confirmed for the southâeastern coast of Brazil. Three other species, Aulostomus strigosus(Aulostomidae), Parablennius pilicornis(Blenniidae) and Epinephelus marginatus(Serranidae) have apparently also crossed the Atlantic from east to west, whereas the great majority of 'amphiâAtlantic' species appears to have their origin in the western Atlantic
Abstract: Some colour variations in the Queen Angelfish (Holacanthus ciliaris) are shown in this paper. These morphs belong to an isolated population resident at Saint Paulâs Rocks, a group of small islands in the tropical central Atlantic. Some factors like homozygous following inbreeding and low genetic flow are considered the probably causes of this phenomenon.
