Richardson David E.

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David E.

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Now showing 1 - 7 of 7
  • Article
    Early life history and fisheries oceanography : new questions in a changing world
    (The Oceanography Society, 2014-12) Llopiz, Joel K. ; Cowen, Robert K. ; Hauff, Martha J. ; Ji, Rubao ; Munday, Philip L. ; Muhling, Barbara A. ; Peck, Myron A. ; Richardson, David E. ; Sogard, Susan M. ; Sponaugle, Su
    In the past 100 years since the birth of fisheries oceanography, research on the early life history of fishes, particularly the larval stage, has been extensive, and much progress has been made in identifying the mechanisms by which factors such as feeding success, predation, or dispersal can influence larval survival. However, in recent years, the study of fish early life history has undergone a major and, arguably, necessary shift, resulting in a growing body of research aimed at understanding the consequences of climate change and other anthropogenically induced stressors. Here, we review these efforts, focusing on the ways in which fish early life stages are directly and indirectly affected by increasing temperature; increasing CO2 concentrations, and ocean acidification; spatial, temporal, and magnitude changes in secondary production and spawning; and the synergistic effects of fishing and climate change. We highlight how these and other factors affect not only larval survivorship, but also the dispersal of planktonic eggs and larvae, and thus the connectivity and replenishment of fish subpopulations. While much of this work is in its infancy and many consequences are speculative or entirely unknown, new modeling approaches are proving to be insightful by predicting how early life stage survival may change in the future and how such changes will impact economically and ecologically important fish populations.
  • Preprint
    Feeding dynamics of Northwest Atlantic small pelagic fishes
    ( 2018-04) Suca, Justin J. ; Pringle, Julie W. ; Knorek, Zofia R. ; Hamilton, Sara L. ; Richardson, David E. ; Llopiz, Joel K.
    Small pelagic fishes represent a critical link between zooplankton and large predators. Yet, the taxonomic resolution of the diets of these important fishes is often limited, especially in the Northwest Atlantic. We examined the diets, along with stable isotope signatures, of five dominant small pelagic species of the Northeast US continental shelf ecosystem (Atlantic mackerel Scomber scombrus, Atlantic herring Clupea harengus, alewife Alosa pseudoharengus, blueback herring Alosa aestivalis, and Atlantic butterfish Peprilus triacanthus). Diet analyses revealed strong seasonal differences in most species. Small pelagic fishes predominantly consumed Calanus copepods, small copepod genera (Pseudocalanus/Paracalanus/Clausocalanus), and Centropages copepods in the spring, with appendicularians also important by number for most species. Krill, primarily Meganyctiphanes norvegica, and hyperiid amphipods of the genera Hyperia and Parathemisto were common in the stomach contents of four of the five species in the fall, with hyperiids common in the stomach contents of butterfish in both seasons and krill common in the stomach contents of alewife in both seasons. Depth and region were also found to be sources of variability in the diets of Atlantic mackerel, Atlantic herring, and alewife (region but not depth) with krill being more often in the diet of alewife in more northerly locations, primarily the Gulf of Maine. Stable isotope data corroborate the seasonal differences in diet but overlap of isotopic niche space contrasts that of dietary overlap, highlighting the differences in the two methods. Overall, the seasonal variability and consumer-specific diets of small pelagic fishes are important for understanding how changes in the zooplankton community could influence higher trophic levels.
  • Article
    Support for the Slope Sea as a major spawning ground for Atlantic bluefin tuna: evidence from larval abundance, growth rates, and particle-tracking simulations
    (Canadian Science Publishing, 2021-10-20) Hernández, Christina M. ; Richardson, David E. ; Rypina, Irina I. ; Chen, Ke ; Marancik, Katrin E. ; Shulzitsk, Kathryn ; Llopiz, Joel K.
    Atlantic bluefin tuna (Thunnus thynnus) are commercially and ecologically valuable, but management is complicated by their highly migratory lifestyle. Recent collections of bluefin tuna larvae in the Slope Sea off northeastern United States have opened questions about how this region contributes to population dynamics. We analyzed larvae collected in the Slope Sea and the Gulf of Mexico in 2016 to estimate larval abundance and growth rates and used a high-resolution regional ocean circulation model to estimate spawning locations and larval transport. We did not detect a regional difference in growth rates, but found that Slope Sea larvae were larger than Gulf of Mexico larvae prior to exogenous feeding. Slope Sea larvae generally backtracked to locations north of Cape Hatteras and would have been retained within the Slope Sea until the early juvenile stage. Overall, our results provide supporting evidence that the Slope Sea is a major spawning ground that is likely to be important for population dynamics. Further study of larvae and spawning adults in the region should be prioritized to support management decisions.
  • Article
    Environmental drivers and trends in forage fish occupancy of the Northeast US shelf
    (Oxford University Press, 2021-11-02) Suca, Justin J. ; Deroba, Jonathan J. ; Richardson, David E. ; Ji, Rubao ; Llopiz, Joel K.
    The Northeast US shelf ecosystem is undergoing unprecedented changes due to long-term warming trends and shifts in regional hydrography leading to changes in community composition. However, it remains uncertain how shelf occupancy by the region's dominant, offshore small pelagic fishes, also known as forage fishes, has changed throughout the late 20th and early 21st centuries. Here, we use species distribution models to estimate the change in shelf occupancy, mean weighted latitude, and mean weighted depth of six forage fishes on the Northeast US shelf, and whether those trends were linked to coincident hydrographic conditions. Our results suggest that observed shelf occupancy is increasing or unchanging for most species in both spring and fall, linked both to gear shifts and increasing bottom temperature and salinity. Exceptions include decreases to observed shelf occupancy by sand lance and decreases to Atlantic herring's inferred habitat suitability in the fall. Our work shows that changes in shelf occupancy and inferred habitat suitability have varying coherence, indicating complex mechanisms behind observed shelf occupancy for many species. Future work and management can use these results to better isolate the aspects of forage fish life histories that are important for determining their occupancy of the Northeast US shelf.
  • Article
    COI metabarcoding of zooplankton species diversity for time-series monitoring of the NW Atlantic continental shelf
    (Frontiers Media, 2022-04-22) Bucklin, Ann ; Batta-Lona, Paola G. ; Questel, Jennifer M. ; Wiebe, Peter ; Richardson, David E. ; Copley, Nancy ; O'Brien, Todd D.
    Marine zooplankton are rapid-responders and useful indicators of environmental variability and climate change impacts on pelagic ecosystems on time scales ranging from seasons to years to decades. The systematic complexity and taxonomic diversity of the zooplankton assemblage has presented significant challenges for routine morphological (microscopic) identification of species in samples collected during ecosystem monitoring and fisheries management surveys. Metabarcoding using the mitochondrial Cytochrome Oxidase I (COI) gene region has shown promise for detecting and identifying species of some – but not all – taxonomic groups in samples of marine zooplankton. This study examined species diversity of zooplankton on the Northwest Atlantic Continental Shelf using 27 samples collected in 2002-2012 from the Gulf of Maine, Georges Bank, and Mid-Atlantic Bight during Ecosystem Monitoring (EcoMon) Surveys by the NOAA NMFS Northeast Fisheries Science Center. COI metabarcodes were identified using the MetaZooGene Barcode Atlas and Database ( specific to the North Atlantic Ocean. A total of 181 species across 23 taxonomic groups were detected, including a number of sibling and cryptic species that were not discriminated by morphological taxonomic analysis of EcoMon samples. In all, 67 species of 15 taxonomic groups had ≥ 50 COI sequences; 23 species had >1,000 COI sequences. Comparative analysis of molecular and morphological data showed significant correlations between COI sequence numbers and microscopic counts for 5 of 6 taxonomic groups and for 5 of 7 species with >1,000 COI sequences for which both types of data were available. Multivariate statistical analysis showed clustering of samples within each region based on both COI sequence numbers and EcoMon counts, although differences among the three regions were not statistically significant. The results demonstrate the power and potential of COI metabarcoding for identification of species of metazoan zooplankton in the context of ecosystem monitoring.
  • Article
    Sensitivity of sand lance to shifting prey and hydrography indicates forthcoming change to the northeast US shelf forage fish complex
    (Oxford University Press, 2021-01-26) Suca, Justin J. ; Wiley, David N. ; Silva, Tammy L. ; Robuck, Anna R. ; Richardson, David E. ; Glancy, Sarah G. ; Clancey, Emily ; Giandonato, Teresa ; Solow, Andrew R. ; Thompson, Michael A. ; Hong, Peter ; Baumann, Hannes ; Kaufman, Les ; Llopiz, Joel K.
    Northern sand lance (Ammodytes dubius) and Atlantic herring (Clupea harengus) represent the dominant lipid-rich forage fish species throughout the Northeast US shelf and are critical prey for numerous top predators. However, unlike Atlantic herring, there is little research on sand lance or information about drivers of their abundance. We use intra-annual measurements of sand lance diet, growth, and condition to explain annual variability in sand lance abundance on the Northeast US Shelf. Our observations indicate that northern sand lance feed, grow, and accumulate lipids in the late winter through summer, predominantly consuming the copepod Calanus finmarchicus. Sand lance then cease feeding, utilize lipids, and begin gonad development in the fall. We show that the abundance of C. finmarchicus influences sand lance parental condition and recruitment. Atlantic herring can mute this effect through intra-guild predation. Hydrography further impacts sand lance abundance as increases in warm slope water decrease overwinter survival of reproductive adults. The predicted changes to these drivers indicate that sand lance will no longer be able to fill the role of lipid-rich forage during times of low Atlantic herring abundance—changing the Northeast US shelf forage fish complex by the end of the century.
  • Article
    The role of sand lances (Ammodytes sp.) in the Northwest Atlantic ecosystem: a synthesis of current knowledge with implications for conservation and management
    (Wiley, 2020-03-20) Staudinger, Michelle D. ; Goyert, Holly ; Suca, Justin J. ; Coleman, Kaycee ; Welch, Linda ; Llopiz, Joel K. ; Wiley, David N. ; Altman, Irit ; Applegate, Andew ; Auster, Peter J. ; Baumann, Hannes ; Beaty, Julia ; Boelke, Deirdre ; Kaufman, Les ; Loring, Pam ; Moxley, Jerry ; Paton, Suzanne ; Powers, Kevin D. ; Richardson, David E. ; Robbins, Jooke ; Runge, Jeffrey A. ; Smith, Brian ; Spiegel, Caleb ; Steinmetz, Halley
    The American sand lance (Ammodytes americanus, Ammodytidae) and the Northern sand lance (A. dubius, Ammodytidae) are small forage fishes that play an important functional role in the Northwest Atlantic Ocean (NWA). The NWA is a highly dynamic ecosystem currently facing increased risks from climate change, fishing and energy development. We need a better understanding of the biology, population dynamics and ecosystem role of Ammodytes to inform relevant management, climate adaptation and conservation efforts. To meet this need, we synthesized available data on the (a) life history, behaviour and distribution; (b) trophic ecology; (c) threats and vulnerabilities; and (d) ecosystem services role of Ammodytes in the NWA. Overall, 72 regional predators including 45 species of fishes, two squids, 16 seabirds and nine marine mammals were found to consume Ammodytes. Priority research needs identified during this effort include basic information on the patterns and drivers in abundance and distribution of Ammodytes, improved assessments of reproductive biology schedules and investigations of regional sensitivity and resilience to climate change, fishing and habitat disturbance. Food web studies are also needed to evaluate trophic linkages and to assess the consequences of inconsistent zooplankton prey and predator fields on energy flow within the NWA ecosystem. Synthesis results represent the first comprehensive assessment of Ammodytes in the NWA and are intended to inform new research and support regional ecosystem‐based management approaches.