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528 results on '"Hofmann, Eileen E."'

2. SPATIAL AND TEMPORAL VARIABILITY OF ATLANTIC SURFCLAM (SPISULA SOLIDISS1MA, DILLWYN 1817) POPULATION DEMOGRAPHICS ALONG THE MIDDLE ATLANTIC BIGHT

Author

Diaz, Mauricio G., Hofmann, Eileen E., Klinck, John M., Munroe, Daphne M., Powell, Eric N., and Scheld, Andrew M.

Subjects
United States. Northeast Fisheries Science Center -- Surveys -- Analysis, Investment analysis -- Surveys -- Health aspects -- Analysis, Climatic changes -- Analysis -- Surveys -- Health aspects, Biological sciences, Zoology and wildlife conservation
Abstract

Trends in Atlantic surfclam (Spisulu solidissima) population demographic parameters were analyzed using age and length observations obtained from NOAA stock surveys conducted from the 1980s to 2010s in six regions distributed along the Middle Atlantic Bight (MAB) continental shelf. Atlantic surfclam asymptotic length and specific growth rate were estimated for each survey region and decade using the von Bertalanffy growth function. Specific mortality rates were estimated using a linearized negative exponential relationship and the maximum Atlantic surfclam age observed in each survey region for each decade. The estimated Atlantic surfclam mean length in the southern regions of the MAB decreased from 127 to 103 mm, about a 19% decrease, over the four decades. The mean length remained stable at about 130-135 mm in the central survey regions in contrast to the mean length of the Georges Bank Atlantic surfclam population which showed an increase from 101 to 135 mm over the four decades. The asymptotic length estimated for the southernmost survey region declined by 20% and remained relatively constant for the other survey regions over the four decades. Estimated specific growth rates remained unchanged for most of the survey regions, with the overall regional mean decreasing from about 0.25 [y.sup.-1] in the 1980s to 0.20 y~' by the 2010s. Specific mortality rates were not significantly different across the survey regions, although the maximum age estimated for the population in the southern survey region decreased by about 36%. This study provides a quantitative assessment of past and ongoing changes in MAB Atlantic surfclam population demographics that can be used to develop projections of responses to stresses imposed by climate change and commercial fishing. KEY WORDS: Atlantic surfclam Spisulu solidissima, population demographics, growth rale, mortality rate. Middle Atlantic Bight, INTRODUCTION The Middle Atlantic Bight (MAB) region, the portion of the Northwest Atlantic continental shelf from Cape Hatteras to Georges Bank (Fig. 1), is characterized by a productive benthic ecosystem [...]

Published
2024
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4. MODELING PERFORMANCE AND SETTLEMENT WINDOWS OF LARVAL EASTERN OYSTER (CRASSOSTREA VIRGINICA) IN DELAWARE BAY

Author

Klein, James C., Powell, Eric N., Kreeger, Danielle A., Ashton-Alcox, Kathryn A., Bushek, David, Zhang, Xiaodong, Thomas, Roger L., Klinck, John M., and Hofmann, Eileen E.

Subjects
Lipids -- Analysis, Crassostrea -- Analysis, Salinity -- Analysis, Oysters -- Analysis, Biological sciences, Zoology and wildlife conservation
Abstract

Oyster population maintenance and growth require a sufficient larval supply competent for metamorphosis and settlement. Larval performance, in terms of growth, development, survival, and metamorphic success, determines the capacity for a larval cohort to effectively settle and establish into an existing population. Exogenous factors influencing larval development include temperature, salinity, food quantity, and food quality. A sufficient diet, composed of balanced protein, lipids, and carbohydrates to meet larval nutritional demands, is required to promote successful metamorphosis. To evaluate the influence of these exogenous factors on oyster settlement potential in Delaware Bay, a well-established biochemically based Crassostrea gigas (Thunberg, 1793) larval model was adapted to simulate Crassostrea virginica (Gmelin, 1791) larval performance under in situ environmental conditions measured during the 2009 to 2011 reproductive seasons at 10 sites across the salinity gradient of Delaware Bay. Variation in the initial egg size and lipid content, and larval food assimilation efficiency was incorporated into the model to represent potential within-cohort phenotypic variability. The middle portion of Delaware Bay along the New Jersey shoreline, bridging the 15-salinity line, generated the most successful larvae each year, whereas the low-salinity reach, on the Delaware side, and Nantuxent Point Reef had more variable success. Survivorship was a function of adequate temperatures and salinities, sufficient food quantity, and favorable food quality defined in part by the protein-to-(lipid-plus-carbohydrate) ratio. Most settlement was predicted by the model to occur between July and September of each year. To validate the model, estimated settlement windows were compared with calculated settlement windows derived from recruitment observations on yearly shell plants. Modeled and recruitment-derived settlement windows agreed well with each other and verified the capacity of the model to accurately forecast in situ larval performance. The oyster larval model, based on measures of lipid, protein, and carbohydrate, successfully passed an important field test, demonstrating the potential of such biochemically based models to reliably evaluate larval performance under real-world conditions. KEY WORDS: Crassostrea virginica, larvae, eastern oyster, performance model, settlement window, biochemical, food, INTRODUCTION Successful oyster population maintenance and growth require a consistent larval supply capable of settlement onto existing beds over time (Coen & Luckenbach 2000, Mann & Powell 2007, Lipcius et [...]

Published
2023
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12. Functioning of Coastal River-Dominated Ecosystems and Implications for Oil Spill Response : FROM OBSERVATIONS TO MECHANISMS AND MODELS

Author

Greer, Adam T., Shiller, Alan M., Hofmann, Eileen E., Wiggert, Jerry D., Warner, Sally J., Parra, Sabrina M., Pan, Chudong, Book, Jeffrey W., Joung, DongJoo, Dykstra, Steven, Krause, Jeffrey W., Dzwonkowski, Brian, Soto, Inia M., Cambazoglu, M. Kemal, Deary, Alison L., Briseño-Avena, Christian, Boyette, Adam D., Kastler, Jessica A., Sanial, Virginie, Hode, Laura, Nwankwo, Uchenna, Chiaverano, Luciano M., O’Brien, Stephan J., Fitzpatrick, Patrick J., Lau, Yee H., Dinniman, Michael S., Martin, Kevin M., Ho, Peng, Mojzis, Allison K., Howden, Stephan D., Hernandez, Frank J., Church, Ian, Miles, Travis N., Sponaugle, Su, Moum, James N., Arnone, Robert A., Cowen, Robert K., Jacobs, Gregg A., Schofield, Oscar, and Graham, William M.

Published
2018

18. NetCDF model output of 4 circum-Antartic model simulations covering the Antarctic Continental Shelf from ADD TIME

Author

Dinniman, Michael, Hofmann, Eileen E., Arrigo, Kevin R., Dinniman, Michael, Hofmann, Eileen E., and Arrigo, Kevin R.

Abstract

Dataset: Circum-Antartic Model: four simulation outputs, NetCDF model output of 4 circum-Antartic model simulations covering the Antarctic Continental Shelf from ADD TIME For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/887777, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1643652, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1643618

Published
2023

19. The Southern Ocean Ecosystem Affects The Entire World

Author

Murphy, Eugene J., Johnston, Nadine M., Hofmann, Eileen E., Phillips, Richard A., Jackson, Jennifer A., Constable, Andrew J., Murphy, Eugene J., Johnston, Nadine M., Hofmann, Eileen E., Phillips, Richard A., Jackson, Jennifer A., and Constable, Andrew J.

Abstract

The Southern Ocean, which flows around the Antarctic continent, is home to vast numbers of unique and remarkable animals, including penguins, albatrosses, petrels, seals, and whales. The ocean bursts into life every spring, fueling a summer feeding and breeding frenzy. During the dark winter months, there is little food and life is very harsh. Human activities such as fishing and pollution are affecting this ecosystem, as is climate change. These ecosystem changes matter beyond the Southern Ocean! Ocean currents carry nutrients and organisms into and out of the Southern Ocean. Many marine mammals and seabirds swim or fly in and out of the Southern Ocean, in search of food and breeding grounds, or to escape the harsh Antarctic winter. These movements and migrations connect the Southern Ocean ecosystem with other marine ecosystems around the world. This means that changes in the Southern Ocean ecosystem can affect ecosystems around the world.

Published
2023

21. Developing priority variables (“ecosystem Essential Ocean Variables” — eEOVs) for observing dynamics and change in Southern Ocean ecosystems

Author

Constable, Andrew J., Costa, Daniel P., Schofield, Oscar, Newman, Louise, Urban, Edward R., Jr., Fulton, Elizabeth A., Melbourne-Thomas, Jessica, Ballerini, Tosca, Boyd, Philip W., Brandt, Angelika, de la Mare, Willaim K., Edwards, Martin, Eléaume, Marc, Emmerson, Louise, Fennel, Katja, Fielding, Sophie, Griffiths, Huw, Gutt, Julian, Hindell, Mark A., Hofmann, Eileen E., Jennings, Simon, La, Hyoung Sul, McCurdy, Andrea, Mitchell, B. Greg, Moltmann, Tim, Muelbert, Monica, Murphy, Eugene, Press, Anthony J., Raymond, Ben, Reid, Keith, Reiss, Christian, Rice, Jake, Salter, Ian, Smith, David C., Song, Sun, Southwell, Colin, Swadling, Kerrie M., Van de Putte, Anton, and Willis, Zdenka

Published
2016
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27. Seasonal habitat preference and foraging behaviour of post-moult Weddell seals in the western Ross Sea

Author

Goetz, Kimberly T., primary, Dinniman, Michael S., additional, Hückstädt, Luis A., additional, Robinson, Patrick W., additional, Shero, Michelle R., additional, Burns, Jennifer M., additional, Hofmann, Eileen E., additional, Stammerjohn, Sharon E., additional, Hazen, Elliott L., additional, Ainley, David G., additional, and Costa, Daniel P., additional

Published
2023
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29. Comparative biogeochemistry–ecosystem–human interactions on dynamic continental margins

Author

Levin, Lisa A., Liu, Kon-Kee, Emeis, Kay-Christian, Breitburg, Denise L., Cloern, James, Deutsch, Curtis, Giani, Michele, Goffart, Anne, Hofmann, Eileen E., Lachkar, Zouhair, Limburg, Karin, Liu, Su-Mei, Montes, Enrique, Naqvi, Wajih, Ragueneau, Olivier, Rabouille, Christophe, Sarkar, Santosh Kumar, Swaney, Dennis P., Wassman, Paul, and Wishner, Karen F.

Published
2015
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31. Figure S1 from Seasonal habitat preference and foraging behaviour of Weddell seals in the western Ross Sea

Author

Goetz, Kimberly T., Dinniman, Michael S., Hückstädt, Luis A., Robinson, Patrick W., Shero, Michelle R., Burns, Jennifer M., Hofmann, Eileen E., Stammerjohn, Sharon E., Hazen, Elliott L., Ainley, David G., and Costa, Daniel P.

Abstract

Figure S1: Four residual plots showing diagnostic information about the fitting procedure and results for all final seasonal models. Model labels are indicated at the top of each 4-panel plot with H and F distinguishing between habitat and foraging models and HORIZ and VERT distinguishing between horizontal and vertical foraging models.

Published
2023
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32. Estuarine Dissolved Organic Carbon Flux from Space: With Application to Chesapeake and Delaware Bays

Author

Signorini, Sergio, Mannino, Antonio, Friedrichs, Marjorie A. M, St‐Laurent, Pierre, Wilkin, John, Tabatabai, Aboozar, Najjar, Raymond G, Hofmann, Eileen E, Da, Fei, Tian, Hanqin, and Yao, Yuanzhi

Subjects
Earth Resources And Remote Sensing, Meteorology And Climatology
Abstract

This study uses a neural network model trained with in situ data, combined with satellite data and hydrodynamic model products, to compute the daily estuarine export of dissolved organic carbon (DOC) at the mouths of Chesapeake Bay (CB) and Delaware Bay (DB) from 2007 to 2011. Both bays show large flux variability with highest fluxes in spring and lowest in fall as well as interannual flux variability (0.18 and 0.27 Tg C/year in 2008 and 2010 for CB; 0.04 and 0.09 Tg C/year in 2008 and 2011 for DB). Based on previous estimates of total organic carbon (TOCexp) exported by all Mid-Atlantic Bight estuaries (1.2 Tg C/year), the DOC export (CB + DB) of 0.3 Tg C/year estimated here corresponds to 25% of the TOCexp. Spatial and temporal covariations of velocity and DOC concentration provide contributions to the flux, with larger spatial influence. Differences in the discharge of fresh water into the bays (74 billion m(exp3)/year for CB and 21 billion m9exp3)/year for DB) and their geomorphologies are major drivers of the differences in DOC fluxes for these two systems. Terrestrial DOC inputs are similar to the export of DOC at the bay mouths at annual and longer time scales but diverge significantly at shorter time scales (days to months). Future efforts will expand to the Mid-Atlantic Bight and Gulf of Maine, and its major rivers and estuaries, in combination with coupled terrestrial-estuarine-ocean biogeochemical models that include effects of climate change, such as warming and CO2 increase.

Published
2019
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47. John H. Steele, 1926–2013

Author

TURNER, ELIZABETH, HOFMANN, EILEEN E., GIFFORD, DIAN J., and HAIDVOGEL, DALE B.

Published
2013

49. Numerical model simulating the sea ice and ocean conditions in the Amundsen Sea over the period Jan. 1, 2006 to Dec. 31, 2013

Author

St-Laurent, Pierre, Hofmann, Eileen E., Sherrell, Robert M., Stammerjohn, Sharon E., Yager, Patricia L., Biddle, Mathew, York, Amber D., St-Laurent, Pierre, Hofmann, Eileen E., Sherrell, Robert M., Stammerjohn, Sharon E., Yager, Patricia L., Biddle, Mathew, and York, Amber D.

Abstract

Numerous coastal polynyas fringe the Antarctic continent and strongly influence the productivity of Antarctic shelf systems. Of the 46 Antarctic coastal polynyas documented in a recent study, the Amundsen Sea Polynya (ASP) stands out as having the highest net primary production per unit area. Incubation experiments suggest that this productivity is partly controlled by the availability of dissolved iron (dFe). As a first step toward understanding the iron supply of the ASP, we introduce four plausible sources of dFe and simulate their steady spatial distribution using conservative numerical tracers. The modeled distributions replicate important features from observations including dFe maxima at the bottom of deep troughs and enhanced concentrations near the ice shelf fronts. A perturbation experiment with an idealized drawdown mimicking summertime biological uptake and subsequent resupply suggests that glacial meltwater and sediment-derived dFe are the main contributors to the prebloom dFe inventory in the top 100 m of the ASP. The sediment-derived dFe depends strongly on the buoyancy-driven overturning circulation associated with the melting ice shelves (the “meltwater pump”) to add dFe to the upper 300 m of the water column. The results support the view that ice shelf melting plays an important direct and indirect role in the dFe supply and delivery to polynyas such as the ASP. The data are from a numerical model simulating the sea ice and ocean conditions in the Amundsen Sea over the period Jan. 1, 2006 to Dec. 31, 2013. The data files provide the daily averaged model fields during this period. The numerical model and experiment are thoroughly described in St-Laurent et al., J. Geophys. Res. Oceans, doi:10.1002/2017jc013162., NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443657 NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443604 NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443315 NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443569

Published
2022

50. The Atlantic surfclam fishery and offshore wind energy development: 2. Assessing economic impacts

Author

Scheld, Andrew M, Beckensteiner, Jennifer, Munroe, Daphne M, Powell, Eric N, Borsetti, Sarah, Hofmann, Eileen E, Klinck, John M, Scheld, Andrew M, Beckensteiner, Jennifer, Munroe, Daphne M, Powell, Eric N, Borsetti, Sarah, Hofmann, Eileen E, and Klinck, John M

Abstract

The Atlantic surfclam (Spisula solidissima) fishery generates approximately USD 30 million in landings revenues annually, distributed across ports throughout the US Mid-Atlantic and Northeast. Overlap between areas of Atlantic surfclam harvests and offshore wind energy leasing make the fishery vulnerable to exclusion and effort displacement as development expands in the region. An existing integrated bioeconomic agent-based model, including spatial dynamics in Atlantic surfclam stock biology, heterogeneous captain behaviour, and federal management processes, was extended to incorporate costs and revenues for fishing vessels and processors and used to evaluate the potential economic effects of offshore wind development on the Atlantic surfclam fishery. Fishing activity and economic outcomes were simulated under different offshore wind energy development scenarios that impose spatial restrictions on Atlantic surfclam vessel fishing and transiting behaviour. Decreases in the number of trips and shifts in the spatial distribution of fishing effort reduced revenues for Atlantic surfclam fishing vessels and processors by ∼3–15% and increased average fishing costs by < 1–5%, with impacts varying across development scenarios and fishing ports. The modelling approach used in this analysis has potential for addressing additional questions surrounding sustainable ocean multi-use and further quantifying interactions between offshore wind energy development and commercial fisheries.

Published
2022
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