Environmentally mediated trends in otolith composition of juvenile Atlantic cod (Gadus morhua)

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in ICES Journal of Marine Science 72 (2015): 2350-2363, doi: 10.1093/icesjms/fsv070.We evaluated the influence of environmental exposure of juvenile Atlantic cod (Gadus morua) to inform interpretations of natal origins and movement patterns using otolith geochemistry. Laboratory rearing experiments were conducted with a variety of temperature (~ 5, 8.5 and 12 °C) and salinity (~ 25, 28.5 and 32 PSU) combinations. We measured magnesium (Mg), manganese (Mn), strontium (Sr) and barium (Ba), expressed as a ratio to calcium (Ca), using laser ablation inductively coupled plasma mass spectrometry (ICP-MS), and stable carbon (δ13C) and oxygen (δ18O) isotopes using isotope ratio monitoring mass spectrometry. Temperature and salinity significantly affected all elements and isotopes measured, with the exception of salinity on Mg:Ca. We detected significant interactions among temperature and salinity for Mn:Ca and Ba:Ca partition coefficients (ratio of otolith chemistry to water chemistry), with significant temperature effects only detected in the 32 and 28.5 PSU salinity treatments. Similarly, we detected a significant interaction between temperature and salinity in incorporation of δ13C, with a significant temperature effect except at intermediate salinity. These results support the contention that environmental mediation of otolith composition varies among species, thus limiting the ability of generalized models to infer life history patterns from chemistry. Our results provide essential baseline information detailing environmental influence on juvenile Atlantic cod otolith composition, punctuating the importance of laboratory validations to translate species-specific otolith composition when inferring in situ life histories and movements.Research funding and support was provided by a Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Grant on Connectivity in Marine Fishes. R. Stanley was supported by an NSERC Postgraduate Scholarship and a Research and Development Corporation of Newfoundland (RDC) student fellowship.2016-04-2

Extreme diving behaviour in devil rays links surface waters and the deep ocean

© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 5 (2014): 4274, doi:10.1038/ncomms5274.Ecological connections between surface waters and the deep ocean remain poorly studied despite the high biomass of fishes and squids residing at depths beyond the euphotic zone. These animals likely support pelagic food webs containing a suite of predators that include commercially important fishes and marine mammals. Here we deploy pop-up satellite archival transmitting tags on 15 Chilean devil rays (Mobula tarapacana) in the central North Atlantic Ocean, which provide movement patterns of individuals for up to 9 months. Devil rays were considered surface dwellers but our data reveal individuals descending at speeds up to 6.0 m s−1 to depths of almost 2,000 m and water temperatures <4 °C. The shape of the dive profiles suggests that the rays are foraging at these depths in deep scattering layers. Our results provide evidence of an important link between predators in the surface ocean and forage species occupying pelagic habitats below the euphotic zone in ocean ecosystems.This research was partially supported by the Portuguese Foundation for Science and Technology/Ministry of Education and Science (FCT/MCTES-MEC) through individual support to P.A. (Cieˆncia 2008/POPH/QREN) and J.F. (SFRH/BPD/66532/2009) and the LARSyS Strategic Project (PEst/OE/EEI/LA00009/2011). This study was support by the US National Science Foundation (OCE 0825148 to S.R.T. and G.B.S.), The Harrison Foundation, Rodney and Elizabeth Berens, the King Abdullah University of Science and Technology (baseline research funds to M.L.B.) and the Woods Hole Oceanographic Institution

Comparison of Plankton Catch by Three Light-Trap Designs in the Northern Gulf of Mexico

The ichthyoplankton catch and zooplankton biomass estimates of three light-trap designs-cylindrical, quatrefoil, and rectangular-were compared over three consecutive nights at an offshore petroleum platform in the northern Gulf of Mexico. The quatrefoil light trap had higher fish and zooplankton abundance estimates than the other two designs. Categorical analysis of the two abundant fish taxa, Opisthonema oglinum and Anchoa spp., indicated that catch by the quatrefoil and rectangular traps was similar, capturing more larvae than juveniles and more O. oglinum than Anchoa spp. relative to cylindrical trap catch. Across all fish species, the quatrefoil captured a greater percentage of larvae. Other ontogenetic and species-specific differences were noted among the light-trap designs. Samples from vertical plankton tows underestimated larger size classes compared to light-trap catch. Light-trap catch per unit effort (CPUE) declined through the night, especially for the quatrefoil, and increased with depth. In contrast, the percentage of larvae captured across all traps increased through the night and decreased with depth, indicating that CPUE was related mostly to juvenile catch. The percentage of larvae also decreased with increasing water current speed

Spatial and isotopic niche partitioning during winter in chinstrap and Adélie penguins from the South Shetland Islands

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ecosphere 6 (2015): art125, doi:10.1890/ES14-00287.1.Closely related species with similar ecological requirements should exhibit segregation along spatial, temporal, or trophic niche axes to limit the degree of competitive overlap. For migratory marine organisms like seabirds, assessing such overlap during the non-breeding period is difficult because of long-distance dispersal to potentially diffuse foraging habitats. Miniaturization of geolocation devices and advances in stable isotope analysis (SIA), however, provide a robust toolset to quantitatively track the movements and foraging niches of wide ranging marine animals throughout much of their annual cycle. We used light-based geolocation tags and analyzed stable carbon and nitrogen isotopes from tail feathers to simultaneously characterize winter movements, habitat utilization, and overlap of spatial and isotopic niches of migratory chinstrap (Pygoscelis antarctica) and Adélie (P. adeliae) penguins during the austral winter of 2012. Chinstrap penguins exhibited a higher diversity of movements and occupied portions of the Southern Ocean from 138° W to 30° W within a narrow latitudinal band centered on 60° S. In contrast, all tracked Adélie penguins exhibited smaller-scale movements into the Weddell Sea and then generally along a counter-clockwise path as winter advanced. Inter-specific overlap during the non-breeding season was low except during the months immediately adjacent to the summer breeding season. Intra-specific overlap by chinstraps from adjacent breeding colonies was higher throughout the winter. Spatial segregation appears to be the primary mechanism to maintain inter- and intra-specific niche separation during the non-breeding season for chinstrap and Adélie penguins. Despite low spatial overlap, however, the data do suggest that a narrow pelagic corridor in the southern Scotia Sea hosted both chinstrap and Adélie penguins for most months of the year. Shared occupancy and similar isotopic signatures of the penguins in that region suggests that the potential for inter-specific competition persists during the winter months. Finally, we note that SIA was able to discriminate eastward versus westward migrations in penguins, suggesting that SIA of tail feathers may provide useful information on population-level distribution patterns for future studies.Funds for the GLS tags were provided by the National Marine Sanctuary Foundation. Additional support for this project was provided by a Woods Hole Oceanographic Devonshire Scholarship as well as funding from the Ocean Life Institute and SeaWorld Bush Gardens Conservation Fund to MJP

Otolith geochemistry does not reflect dispersal history of clownfish larvae

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Coral Reefs 29 (2010): 883-891, doi:10.1007/s00338-010-0652-z.Natural geochemical signatures in calcified structures are commonly employed to retrospectively estimate dispersal pathways of larval fish and invertebrates. However, the accuracy of the approach is generally untested due to the absence of individuals with known dispersal histories. We used genetic parentage analysis (genotyping) to divide 110 new recruits of the orange clownfish, Amphiprion percula, from Kimbe Island, Papua New Guinea, into two groups: “self-recruiters” spawned by parents on Kimbe Island and “immigrants” that had dispersed from distant reefs (>10km away). Analysis of daily increments in sagittal otoliths found no significant difference in PLDs or otolith growth rates between self-recruiting and immigrant larvae. We also quantified otolith Sr/Ca and Ba/Ca ratios during the larval phase using laser ablation inductively coupled plasma mass spectrometry. Again, we found no significant differences in larval profiles of either element between self-recruits and immigrants. Our results highlight the need for caution when interpreting otolith dispersal histories based on natural geochemical tags in the absence of water chemistry data or known-origin larvae with which to test the discriminatory ability of natural tags.Research was supported by the Australian Research Council, the Coral Reef Initiatives for the Pacific (CRISP), the Global Environmental Facility CRTR Connectivity Working Group, the Total Foundation, a National Science Foundation grant (#0424688) to SRT, and a National Science Foundation Graduate Research Fellowship to MLB

High connectivity among locally adapted populations of a marine fish (Menidia menidia)

Author Posting. © Ecological Society of America, 2010. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 91 (2010): 3526–3537, doi:10.1890/09-0548.1.Patterns of connectivity are important in understanding the geographic scale of local adaptation in marine populations. While natural selection can lead to local adaptation, high connectivity can diminish the potential for such adaptation to occur. Connectivity, defined as the exchange of individuals among subpopulations, is presumed to be significant in most marine species due to life histories that include widely dispersive stages. However, evidence of local adaptation in marine species, such the Atlantic silverside, Menidia menidia, raises questions concerning the degree of connectivity. We examined geochemical signatures in the otoliths, or ear bones, of adult Atlantic silversides collected in 11 locations along the northeastern coast of the United States from New Jersey to Maine in 2004 and eight locations in 2005 using laser ablation inductively coupled plasma mass spectrometry (ICP-MS) and isotope ratio monitoring mass spectrometry (irm-MS). These signatures were then compared to baseline signatures of juvenile fish of known origin to determine natal origin of these adult fish. We then estimated migration distances and the degree of mixing from these data. In both years, fish generally had the highest probability of originating from the same location in which they were captured (0.01–0.80), but evidence of mixing throughout the sample area was present. Furthermore, adult M. menidia exhibit highly dispersive behavior with some fish migrating over 700 km. The probability of adult fish returning to natal areas differed between years, with the probability being, on average, 0.2 higher in the second year. These findings demonstrate that marine species with largely open populations are capable of local adaptation despite apparently high gene flow.This work was funded by the National Science Foundation (grant OCE-0425830 to D. O. Conover and grant OCE- 0134998 to S. R. Thorrold) and the New York State Department of Environmental Conservation

Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks

Conservation and management efforts for white sharks (Carcharodon carcharias) remain hampered by a lack of basic demographic information including age and growth rates. Sharks are typically aged by counting growth bands sequentially deposited in their vertebrae, but the assumption of annual deposition of these band pairs requires testing. We compared radiocarbon (Δ14C) values in vertebrae from four female and four male white sharks from the northwestern Atlantic Ocean (NWA) with reference chronologies documenting the marine uptake of 14C produced by atmospheric testing of thermonuclear devices to generate the first radiocarbon age estimates for adult white sharks. Age estimates were up to 40 years old for the largest female (fork length [FL]: 526 cm) and 73 years old for the largest male (FL: 493 cm). Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies, hint at possible sexual dimorphism in growth rates, and raise concerns that white shark populations are considerably more sensitive to human-induced mortality than previously thought

Connectivity and resilience of coral reef metapopulations in marine protected areas : matching empirical efforts to predictive needs

© 2009 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution Noncommercial License. The definitive version was published in Coral Reefs 28 (2009): 327-337, doi:10.1007/s00338-009-0466-z.Design and decision-making for marine protected areas (MPAs) on coral reefs require prediction of MPA effects with population models. Modeling of MPAs has shown how the persistence of metapopulations in systems of MPAs depends on the size and spacing of MPAs, and levels of fishing outside the MPAs. However, the pattern of demographic connectivity produced by larval dispersal is a key uncertainty in those modeling studies. The information required to assess population persistence is a dispersal matrix containing the fraction of larvae traveling to each location from each location, not just the current number of larvae exchanged among locations. Recent metapopulation modeling research with hypothetical dispersal matrices has shown how the spatial scale of dispersal, degree of advection versus diffusion, total larval output, and temporal and spatial variability in dispersal influence population persistence. Recent empirical studies using population genetics, parentage analysis, and geochemical and artificial marks in calcified structures have improved the understanding of dispersal. However, many such studies report current self-recruitment (locally produced settlement/settlement from elsewhere), which is not as directly useful as local retention (locally produced settlement/total locally released), which is a component of the dispersal matrix. Modeling of biophysical circulation with larval particle tracking can provide the required elements of dispersal matrices and assess their sensitivity to flows and larval behavior, but it requires more assumptions than direct empirical methods. To make rapid progress in understanding the scales and patterns of connectivity, greater communication between empiricists and population modelers will be needed. Empiricists need to focus more on identifying the characteristics of the dispersal matrix, while population modelers need to track and assimilate evolving empirical results.Work by CB Paris was supported by the National Science Foundation grant NSF-OCE 0550732. Work by M-A Coffroth and SR Thorrold was supported by the National Science Foundation grant NSF-OCE 0424688. Work by TL Shearer was supported by an International Cooperative Biodiversity Group grant R21 TW006662-01 from the Fogarty International Center at the National Institutes of Health

External tagging does not affect the feeding behavior of a coral reef fish, Chaetodon vagabundus (Pisces: Chaetodontidae)

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of for personal use, not for redistribution. The definitive version was published in Environmental Biology of Fishes 86 (2009): 447-450, doi:10.1007/s10641-009-9545-9.Increasingly, the ability to recognize individual fishes is important for studies of population dynamics, ecology, and behavior. Although a variety of methods exist, external tags remain one of the most widely applied because they are both effective and cost efficient. However, a key assumption is that neither the tagging procedure nor the presence of a tag negatively affects the individual. While this has been demonstrated for relatively coarse metrics such as growth and survival, few studies have examined the impact of tags and tagging on more subtle aspects of behavior. We tagged adult vagabond butterflyfish (Chaetodon vagabundus) occupying a 30-ha insular reef in Kimbe Bay, Papua New Guinea, using a commonly-utilized t-bar anchor tag. We quantified and compared feeding behavior (bite rate), which is sensitive to stress, of tagged and untagged individuals over four separate sampling periods spanning four months post-tagging. Bite rates did not differ between tagged and untagged individuals at each sampling period and, combined with additional anecdotal observations of normal pairing behavior and successful reproduction, suggest that tagging did not adversely affect individuals.The authors gratefully acknowledge funding from the Fulbright Program, National Science Foundation and the Australian Research Council