Sea levels fluctuated following glacial cycles during the Pleistocene, reaching approximately 115-130m below current sea levels in the Indian and Pacific Oceans during the last glacial maximum 17,000 years before present. The effects of these sea level fluctuations on population structure have been shown in many near-shore marine taxa, revealing several common patterns. However, the underlying mechanisms behind these observed patterns are largely unknown. Drops in sea level affect the distribution of shallow marine biota, exposing the continental shelf on a global scale, and displacing coral reef habitat to steep slopes where shelf breaks are shallow. In these circumstances, we expect that species inhabiting lagoons should show reduced genetic diversity relative to species inhabiting more stable outer reefs. Here, I tested this expectation on the scale of an entire ocean-basin with four wrasses (genus Halichoeres): H. claudia (N=194, with ocean-wide distribution) and H. ornatissimus (N=346, a Hawaiian endemic) inhabit seaward reef slopes, whereas H. trimaculatus (N=239) and H. margaritaceus (N= 118) inhabit lagoons and shallow habitats throughout the Pacific. Two mitochondrial markers (cytochrome oxidase I and control region) were sequenced to resolve population structure and history of each species. Haplotype and nucleotide diversity were similar among all four species. The outer reef species showed significantly less population structure, consistent with longer pelagic larval durations and a historically stable population. Mismatch distributions and significant negative Fu’s F values indicate Pleistocene population expansion for all species, and (contrary to expectations) reduced genetic diversity in the outer slope species. These data indicate that lagoonal species may persist through the loss of habitat, but are restricted to isolated refugia during lower sea level stands, which may inflate genetic diversity during high sea levels. Outer reef slope species on the other hand have homogeneous and well-connected populations through their entire ranges regardless of sea level fluctuations. These findings contradict the hypothesis that shallow species are less genetically diverse as a consequence of glacial cycles. / text

Made available in DSpace on 2015-04-17T14:55:29Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1643253 bytes, checksum: 663b93e288d71dbedb37bcae9e72b850 (MD5) Previous issue date: 2013-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Damselfishes play key roles in reef environments and are widely used as models in ecological and behavioral studies.During the reproductive period, the damselfishes present strategies involving benthonic spawning. The parental care is performed by the male who, during the days of egg development, expelled all potential predators that try to attack their territory. It was studied here the behavioral ecology during spawning period and the reproductive success of Stegastes sanctipauli, a damselfish endemic to the remote St. Peter and St. Paul s Archipelago (Mid Atlantic Ridge, Brazil). Nest abundance was negatively influenced by depth and abundance of Caranx lugubris, an important damselfish predator. The number of clutches within male s nests was positively influenced by depth, nest area, and substrate inclination, with deeper, bigger and more inclined nests sheltering more clutches. Number of clutches within nests varied along the lunar cycle, peaking at two days before the new moon. Egg loss per clutch per day ranged from 3.5% to 50% and was positively influenced by the initial number of eggs laid by females and moon phase, with highest losses recorded also in the days before the new moon. Frequency of agonistic interactions increased with nest size. Bigger nests, that shelter more clutches, are possibly more attractive to potential egg predators. Species most frequently recorded attempting to predate S. sanctipauli eggs were the conspecifics, heterospecifics damselfishes (Chromis multillineata and Abudefduf saxatilis), Malacoctenus sp. and Halichoeres radiatus. Although, no successful predation events was witnessed, experimental offer of clutches and analysis of bite scars revealed Melichthys niger as the main potential predator of S. sanctipauli eggs. Filial cannibalism of eggs was frequently observed, and may be pointed as a major cause of S. sanctipauli embryo mortality. / Os peixes donzeladesempenham um importante papel nos ambientes recifais e são amplamente utilizados como modelo para estudos comportamentais. Durante o período reprodutivo, as donzelas apresentam estratégias que envolvem desova bentônica. O cuidado parental é realizado pelo macho que, durante o período de desenvolvimento dos ovos, expulsa todos os potenciais predadores que tentam invadir seu território.Neste estudo foi avaliada a ecologia comportamental durante a desova e o sucesso reprodutivo de Stegastes sanctipauli, donzela endêmica do remoto Arquipélago de São Pedro e de São Paulo. A abundância de ninhos foi influenciada negativamente pela profundidade e abundância de Caranx lugubris, um importante predador de donzelas. O número de desovas dentro dos ninhos de cada macho foi positivamente influenciado pela profundidade, área do ninho, e inclinação do substrato. Ninhos mais fundos, maiores e mais inclinados apresentaram um maior número de desovas. O número de desovas variou ao longo do ciclo lunar, atingindo um pico dois dias antes da lua nova. A perda de ovos por desova por dia variou de 3,5% a 50% e foi influenciado positivamente pelo número inicial de ovos desovados pelas fêmeas e pelas fases da lua, com as maiores perdas registradas também nos dias que antecedema lua nova. A frequência de interações agonísticas foi influenciada positivamente pelo tamanho do ninho. Ninhos maiores, que abrigam mais desovas, são possivelmente mais atraentes para potenciais predadores de ovos. As espécies registradas com maior frequência tentando invadir o território de S. sanctipauli foram os próprios coespecíficos, donzelas heteroespecíficas (Chromis multillineata e Abudefduf saxatilis), Malacoctenus sp e Halichoeres radiatus. Apesar de não ter sido registrado sucesso em tentativas de predação de ovos durante as observações comportamentais, a oferta experimental de desovas e análise de cicatrizes de mordidas revelou Melichthys niger como o principal potencial predador de ovos de S. sanctipauli. O canibalismo filial de ovos foi um comportamento frequentemente observado, e pode ser apontadotambém comouma das principais causas de mortalidade embrionária de S. sanctipauli.

This study targets the poorly described egg and larval stages of wrasses and parrotfishes that as adults inhabit coral reefs and seagrasses in the western central Atlantic. Descriptions are provided to allow laboratory identification of the egg and larval stages of these fishes. Accounts are given for 16 of the 20 species of labrid and six of the 14 species of scarids that occur here. The biological, hydrographic, and meteorological data from four oceanographic surveys of the southern Straits of Florida were analyzed to provide a synthesis of the effects of the environment on the distribution of larval fishes occupying a region that is influenced by geostrophic currents and mesoscale recirculation features. Results indicate these oceanographic phenomena play an important role in influencing the distribution of these fishes in their pelagic nursery habitat. The most striking evidence for this comes from the close association of high abundances of fish larvae with the Tortugas Gyre, a semi-permanent mesoscale eddy frequently present off the western Florida Keys. Most species were found in greatest abundance near the center of the eddy, while others were limited to offshore waters along its periphery in deeper depth strata. Older larvae occurred more frequently than younger stages. Those taxa most abundant near the center of the eddy were also more often taken as older larvae. Two hypotheses are proposed to account for larval accumulation in the center of the eddy, which are not mutually exclusive. The first is based on advection of passive larvae that are cyclonically entrained into the center of the eddy along the horizontal plane, while the second provides for a cascade of ecological effects that originate from eddy-induced upwelling in the vertical plane. Diel and ontogenetic effects were shown to be important components of the vertical distribution patterns displayed by these fishes. The vertical distribution of most species within the top 115 m of the water column was non-uniform. Mean depths of most larvae were deeper during the day than at night, with older stage larvae occurring deeper than younger stages.