Time filter

Source Type

Leis J.M.,University of Tasmania | Leis J.M.,Australian Museum Research Institute | Siebeck U.E.,University of Queensland | Hay A.C.,Australian Museum Research Institute | And 3 more authors.
Marine Ecology Progress Series | Year: 2015

Larval coral-reef fishes have good orientation abilities. Through-water orientation of larvae in some species is location-dependent at meso-scales <10s of km, whereas other species have location-independent orientation at meso-scales. In situ observation of the damselfish Chromis atripectoralis showed that settlement-stage larvae swam in a southerly direction (mean = 175 ± 11°) at 100 to 1000 m from shore, both east and west of Lizard Island, northern Great Barrier Reef (NGBR), in 10 datasets from 1998 to 2008. Wind direction did not directly influence throughwater swimming direction at NGBR. During 2014, in situ diver observation tested if orientation of C. atripectoralis differed regionally in the central Great Barrier Reef (CGBR), 620 km south of NGBR, and in the New Caledonia reef lagoon (NCRL), 1950 km east of CGBR. In all 3 regions, >90% of larvae swam directionally with similar precision and speeds, and with significant amongindividual orientation. Yet through-water orientation was easterly at CGBR (72 ± 30°) and NCRL (87 ± 20°), and significantly different from NGBR. Over-bottom orientation (i.e. the result of current and larval swimming), measured by GPS at start and end of observing each larva, was weak east-southeasterly at NGBR (116 ± 40°, p = 0.045), not significantly directional at CGBR, and strongly westerly at NCRL (246 ± 28°, p = 0.0006), indicating that dispersal of C. atripectoralis is both current-and behaviour-dependent. This is the first report of location-dependent larval fish orientation at a regional scale. This might be an evolutionary response to regional hydrodynamic conditions to limit downstream dispersal. © Inter-Research 2015. Source

Cuif M.,CIRAD - Agricultural Research for Development | Cuif M.,Institute Of Recherche Pour Le Developpement Ird | Cuif M.,IRD Montpellier | Cuif M.,Agro ParisTech | And 6 more authors.
Journal of Experimental Marine Biology and Ecology | Year: 2014

Quantifying the larval dispersal component of population connectivity is extremely challenging due to the many difficulties associated with directly observing larvae in their marine environment. Transgenerational isotope labeling is a recent empirical technique that addresses this challenge. It relies on the transmission of an artificially enriched stable isotope (e.g., 137Ba) from gravid females to the embryonic otoliths of their offspring, allowing for mass permanent marking of larvae. Before implementing transgenerational isotope labeling in the wild, it is essential to investigate the transmission longevity of the mark from females to larvae and to assess the potential negative effects on females and their offspring. We injected females of the Humbug damselfish, Dascyllus aruanus, with an enriched 137Ba solution and reared the resulting progeny to test the marking success and the transmission longevity of the mark, as well as determine potential effects of transgenerational isotope labeling on spawning frequency and size of 1-day eggs and 2-day larvae. Three different single-injection dosages (0.5, 1 and 5μg of 137Bag-1 fish weight) were tested, as well as monthly repeated injections of the lowest dosage over a whole reproductive season. We implemented a new method that allows extracting otoliths of newly hatched larvae and analyzing them using laser ablation coupled plasma mass spectrometry (ICP-MS). We showed that for D. aruanus, injection with a low dose (0.5μg 137Bag-1 fish weight) produced consistently significantly marked larvae with a half-life for successful enriched Ba mark transmission of approximately 1month, and that monthly repeated injections of this dose did not negatively impact spawning success or condition of eggs and larvae. Monthly repeated injections of enriched Ba isotope injections at 0.5μg 137Bag-1 fish weight will therefore present an effective means of mass marking D. aruanus larvae throughout an entire reproductive season. © 2014 Elsevier B.V. Source

Read T.C.,Laboratory of marine biology and ecology | Read T.C.,Griffith University | Wantiez L.,University of New Caledonia | Werry J.M.,Griffith University | And 4 more authors.
PLoS ONE | Year: 2014

Marine megafauna tend to migrate vast distances, often crossing national borders and pose a significant challenge to managers. This challenge is particularly acute in the Pacific, which contains numerous small island nations and thousands of kilometers of continental margins. The green sea turtle, Chelonia mydas, is one such megafauna that is endangered in Pacific waters due to the overexploitation of eggs and adults for human consumption. Data from long-term tagging programs in Queensland (Australia) and New Caledonia were analysed to investigate the migrations by C. mydas across the Coral Sea between their nesting site and their feeding grounds. A review of data collected over the last 50 years by different projects identified multiple migrations of C. mydas to and from New Caledonia (n = 97) and indicate that turtles foraging in New Caledonia nest in the Great Barrier Reef (Australia) and vice versa. Several explanations exist for turtles exhibiting this energetically costly movement pattern from breeding to distant foraging grounds (1200-2680 km away) despite viable foraging habitat being available in the local vicinity. These include hatchling drift, oceanic movements and food abundance predictability. Most of the tag recoveries in New Caledonia belonged to females from the south Great Barrier Reef genetic stock. Some females (n = 2) even showed fidelity to foraging sites located 1200 km away from the nesting site located in New Caledonia. This study also reveals previously unknown migrations pathways of turtles within the Coral Sea. © 2014 Read et al. Source

Read T.C.,Laboratory of marine biology and ecology | Read T.C.,Griffith University | Fitzsimmons N.N.,Griffith University | Wantiez L.,University of New Caledonia | And 9 more authors.
Wildlife Research | Year: 2015

Context Migratory species are known to pose a challenge for conservation because it is essential to understand their complex life history in order to implement efficient conservation actions. Aims In New Caledonia, large seagrass habitats in the Grand Lagon Sud (GLS) are home to resident green turtles (Chelonia mydas) of unknown origins. To assess the stock composition in the GLS, 164 foraging turtles were sampled for genetic analysis of ∼770 base pairs of the mitochondrial DNA (mtDNA) control region. Methods Foraging turtles ranging in size from 48.0 to 108.4cm curved carapace length were captured at five different sites within the GLS between September 2012 and December 2013. To provide baseline data for mixed stock analysis, published data from rookeries were used in addition to 105 samples collected at rookeries in the d'Entrecasteaux Islands and Chesterfield Islands in New Caledonia and at Malekula Island in Vanuatu. Exact tests of population differentiation and pairwise FST estimates were used to test for differences in mtDNA haplotype frequencies. Key results These analyses indicated that rookeries in the d'Entrecasteaux Islands and Vanuatu form unique management units and that the Chesterfield Islands rookeries are linked to the Coral Sea management unit. Mixed stock analysis indicated the highest proportion (mean≤0.63) of foraging turtles originate from the d'Entrecasteaux stock. Conclusions The larger contribution is estimated to be from a large rookery from New Caledonia, but smaller contributions are suggested from other rookeries in the South Pacific. Implications Marine conservation policies in New Caledonia need to consider the links between the foraging and nesting populations of C. mydas in New Caledonia and other rookeries and foraging grounds in the Coral Sea. Journal compilation © CSIRO 2015. Source

Discover hidden collaborations