Walsh Harvey J.

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Walsh
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Harvey J.
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  • Preprint
    Otolith geochemistry does not reflect dispersal history of clownfish larvae
    ( 2010-06) Berumen, Michael L. ; Walsh, Harvey J. ; Raventos, N. ; Planes, Serge ; Jones, Geoffrey P. ; Starczak, Victoria R. ; Thorrold, Simon R.
    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.
  • Article
    Biophysical mechanisms of larval fish ingress into Chesapeake Bay
    (Inter-Research, 2005-11-21) Hare, Jonathan A. ; Thorrold, Simon R. ; Walsh, Harvey J. ; Reiss, Christian S. ; Valle-Levinson, Arnoldo ; Jones, Cynthia M.
    Selective tidal stream transport is hypothesized as a dominant mechanism by which larvae of marine animals move through estuarine openings. For larvae moving from the shelf to estuarine habitats, selective tidal stream transport proposes that larvae are higher in the water column during flood tide and lower in the water column during ebb tide. Although a number of studies conclude that selective tidal stream transport is the mechanism responsible for larval ingress, few studies consider alternative mechanisms or consider passive explanations for tidal patterns in larval distributions. We examined the biophysical mechanisms responsible for larval ingress into Chesapeake Bay using an Eulerian approach. We made flux calculations for 3 species and partitioned flux estimates among 3 different ingress mechanisms (wind forcing, residual bottom inflow and tidal). For the Atlantic croaker Micropogonias undulatus (Sciaenidae), all 3 mechanisms of ingress contributed to the net up-estuary flux of larvae, but tidal mechanisms become more important for larger sizes. Net up-estuary flux of the Atlantic menhaden Brevoortia tyrannus (Clupeidae) was dominated by residual bottom inflow and wind forcing. Ingress of the summer flounder Paralichthys dentatus (Paralichthyidae) was dominated by tidal mechanisms, and the importance of tides increased with developmental stage. We found little evidence for the hypothesis that tidal patterns in larval distributions resulted from passive processes (water mass-specific distributions, buoyancy, vertical mixing), thereby supporting the hypothesis that tidal patterns resulted from active behaviors. However, our estimates of vertical mixing were not direct and additional work is needed to examine the role of vertical mixing in influencing vertical distributions in areas with strong tides. We conclude that a combination of wind forcing, residual bottom inflow, and selective tidal stream transport are responsible for the ingress of larval fishes into Chesapeake Bay, and that the relative importance of the 3 mechanisms differs among species and changes with larval development.
  • Article
    Identification of larval sea basses (Centropristis spp.) using ribosomal DNA-specific molecular assays
    (U.S. Dept. of Commerce, NOAA, 2008) Vandersea, Mark W. ; Litaker, R. Wayne ; Marancik, Katrin E. ; Hare, Jonathan A. ; Walsh, Harvey J. ; Lem, Siya ; West, Melissa A. ; Wyanski, David M. ; Laban, Elisabeth H. ; Tester, Patricia A.
    The identification of sea bass (Centropristis) larvae to species is difficult because of similar morphological characters, spawning times, and overlapping species ranges. Black sea bass (Centropristis striata) is an important fishery species and is currently considered to be overfished south of Cape Hatteras, North Carolina. We describe methods for identifying three species of sea bass larvae using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) assays based on species-specific amplification of rDNA internal transcribed spacer reg ions. The assays were tested against DNA of ten other cooccurring reef fish species to ensure the assay’s specificity. Centropristis larvae were collected on three cruises during cross-shelf transects and were used to validate the assays. Seventysix Centropristis larvae were assayed and 69 (91%) were identified successfully. DNA was not amplified from 5% of the larvae and identification was inconclusive for 3% of the larvae. These assays can be used to identify sea bass eggs and larvae and will help to assess spawning locations, spawning times, and larval dispersal.
  • Article
    Juvenile fish assemblages collected on unconsolidated sediments of the southeast United States continental shelf
    (U.S. Department of Commerce, NOAA, 2006) Walsh, Harvey J. ; Marancik, Katrin E. ; Hare, Jonathan A.
    Patterns were investigated in juvenile fish use of unconsolidated sediments on the southeast United States continental shelf off Georgia. Juvenile fish and environmental data were sampled at ten stations along a 110-km cross-shelf transect, including four stations surrounding Gray’s Reef National Marine Sanctuary (Gray’s Reef NMFS). Cross-shelf stations were sampled approximately quarterly from spring 2000 to winter 2002. Additional stations were sampled on three transects inshore of Gray’s Reef NMS and four transects offshore of the Sanctuary during three cruises to investigate along-shelf patterns in the juvenile fish assemblages. Samples were collected in beam trawls, and 121 juvenile taxa, of which 33 were reef-associated species, were identif ied. Correspondence analysis on untransformed juvenile fish abundance indicated a cross-shelf gradient in assemblages, and the station groupings and assemblages varied seasonally. During the spring, fall, and winter, three cross-shelf regions were identified: inner-shelf, mid-shelf, and outer-shelf regions. In the summer, the shelf consisted of a single juvenile fish assemblage. Water depth was the primary environmental variable correlated with cross-shelf assemblages. However, salinity, density, and water column stratification also correlated with the distribution of assemblages during the spring, fall, and winter, and along with temperature likely inf luenced the distribution of juvenile fish. No along-shelf spatial patterns were found in the juvenile fish assemblages, but the along-shelf dimension sampled was small (~60 km). Our results revealed that a number of commercially and recreationally important species used unconsolidated sediments on the shelf off Georgia as juvenile habitat. We conclude that management efforts would be improved through a greater recognition of the importance of these habitats to fish production and the interconnectedness of multiple habitats in the southeast U.S. continental shelf ecosystem.
  • Article
    It's about time: a synthesis of changing phenology in the Gulf of Maine ecosystem
    (Wiley, 2019-04-22) Staudinger, Michelle D. ; Mills, Katherine E. ; Stamieszkin, Karen ; Record, Nicholas R. ; Hudak, Christine A. ; Allyn, Andrew ; Diamond, Antony ; Friedland, Kevin D. ; Golet, Walter J. ; Henderson, Meghan Elisabeth ; Hernandez, Christina M. ; Huntington, Thomas G. ; Ji, Rubao ; Johnson, Catherine L. ; Johnson, David Samuel ; Jordaan, Adrian ; Kocik, John ; Li, Yun ; Liebman, Matthew ; Nichols, Owen C. ; Pendleton, Daniel ; Richards, R. Anne ; Robben, Thomas ; Thomas, Andrew C. ; Walsh, Harvey J. ; Yakola, Keenan
    The timing of recurring biological and seasonal environmental events is changing on a global scale relative to temperature and other climate drivers. This study considers the Gulf of Maine ecosystem, a region of high social and ecological importance in the Northwest Atlantic Ocean and synthesizes current knowledge of (a) key seasonal processes, patterns, and events; (b) direct evidence for shifts in timing; (c) implications of phenological responses for linked ecological‐human systems; and (d) potential phenology‐focused adaptation strategies and actions. Twenty studies demonstrated shifts in timing of regional marine organisms and seasonal environmental events. The most common response was earlier timing, observed in spring onset, spring and winter hydrology, zooplankton abundance, occurrence of several larval fishes, and diadromous fish migrations. Later timing was documented for fall onset, reproduction and fledging in Atlantic puffins, spring and fall phytoplankton blooms, and occurrence of additional larval fishes. Changes in event duration generally increased and were detected in zooplankton peak abundance, early life history periods of macro‐invertebrates, and lobster fishery landings. Reduced duration was observed in winter–spring ice‐affected stream flows. Two studies projected phenological changes, both finding diapause duration would decrease in zooplankton under future climate scenarios. Phenological responses were species‐specific and varied depending on the environmental driver, spatial, and temporal scales evaluated. Overall, a wide range of baseline phenology and relevant modeling studies exist, yet surprisingly few document long‐term shifts. Results reveal a need for increased emphasis on phenological shifts in the Gulf of Maine and identify opportunities for future research and consideration of phenological changes in adaptation efforts.