42 results on '"Santora JA"'
Search Results
2. Climate-ecosystem change off southern California: Time-dependent seabird predator-prey numerical responses
- Author
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Sydeman, WJ, Thompson, SA, Santora, JA, Koslow, JA, Goericke, R, and Ohman, MD
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Stratification ,Upwelling ,Krill ,Northern anchovy ,Rockfish ,Mesopelagic fish ,Seabirds ,Negative binomial models ,Time series ,Geochemistry ,Oceanography ,Ecology - Abstract
Climate change may increase both stratification and upwelling in marine ecosystems, but these processes may affect productivity in opposing or complementary ways. For the Southern California region of the California Current Ecosystem (CCE), we hypothesized that changes in stratification and upwelling have affected marine bird populations indirectly through changes in prey availability. To test this hypothesis, we derived trends and associations between stratification and upwelling, the relative abundance of potential prey including krill and forage fish, and seabirds based on the long-term, multi-disciplinary CalCOFI/CCE-LTER program. Over the period 1987 through 2011, spring and summer seabird density (all species combined) declined by ~2% per year, mostly in the northern sector of the study region. Krill showed variable trends with two species increasing and one deceasing, resulting in community reorganization. Nearshore forage fish, dominated by northern anchovy (Engraulis mordax) as well as offshore mesopelagic species, show declines in relative abundance over this period. The unidirectional decline in springtime seabird density is largely explained by declining nearshore fish abundance in the previous season (winter). Interannual variability in seabird density, especially in the 2000s, is explained by variability in krill abundance. Changes in the numerical responses of seabirds to prey abundance correspond to a putative ecosystem shift in 1998-1999 and support aspects of optimal foraging (diet) theory. Predator-prey interactions and numerical responses clearly explain aspects of the upper trophic level patterns of change in the pelagic ecosystem off southern California.
- Published
- 2015
3. State of the California current 2013-14: El niño looming
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Leising, AW, Schroeder, ID, Bograd, SJ, Bjorkstedt, EP, Field, J, Sakuma, K, Abell, J, Robertson, RR, Tyburczy, J, Peterson, WT, Brodeur, R, Barceló, C, Auth, TD, Daly, EA, Campbell, GS, Hildebrand, JA, Suryan, RM, Gladics, AJ, Horton, CA, Kahru, M, Manzano-Sarabia, M, McClatchie, S, Weber, ED, Watson, W, Santora, JA, Sydeman, WJ, Melin, SR, Delong, RL, Largier, J, Kim, SY, Chavez, FP, Golightly, RT, Schneider, SR, Warzybok, P, Bradley, R, Jahncke, J, Fisher, J, and Peterson, J
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Fisheries Sciences ,Fisheries - Abstract
In 2013, the California current was dominated by strong coastal upwelling and high productivity. Indices of total cumulative upwelling for particular coastal locations reached some of the highest values on record. Chlorophyll a levels were high throughout spring and summer. Catches of upwelling-related fish species were also high. After a moderate drop in upwelling during fall 2013, the California current system underwent a major change in phase. Three major basin-scale indicators, the PDO, the NPGO, and the ENSO-MEI, all changed phase at some point during the winter of 2013/14. The PDO changed to positive values, indicative of warmer waters in the North Pacific; the NPGO to negative values, indicative of lower productivity along the coast; and the MEI to positive values, indicative of an oncoming El Niño. Whereas the majority of the California Current system appears to have transitioned to an El Niño state by August 2014, based on decreases in upwelling and chlorophyll a concentration, and increases in SST, there still remained pockets of moderate upwelling, cold water, and high chlorophyll a biomass at various central coast locations, unlike patterns seen during the more major El Niños (e.g., the 97-98 event). Catches of rockfish, market squid, euphausiids, and juvenile sanddab remained high along the central coast, whereas catches of sardine and anchovy were low throughout the CCS. 2014 appears to be heading towards a moderate El Niño state, with some remaining patchy regions of upwellingdriven productivity along the coast. Superimposed on this pattern, three major regions have experienced possibly non-El Niño-related warming since winter: the Bering Sea, the Gulf of Alaska, and offshore of southern California. It is unclear how this warming may interact with the predicted El Niño, but the result will likely be reduced growth or reproduction for many key fisheries species.
- Published
- 2014
4. State of the California current 2012-13: No such thing as an “average” year
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Wells, BK, Schroeder, ID, Santora, JA, Hazen, EL, Bograd, SJ, Bjorkstedt, EP, Loeb, VJ, McClatchie, S, Weber, ED, Watson, W, Thompson, AR, Peterson, WT, Brodeur, RD, Harding, J, Field, J, Sakuma, K, Hayes, S, Mantua, N, Sydeman, WJ, Losekoot, M, Thompson, SA, Largier, J, Kim, SY, Chavez, FP, Barceló, C, Warzybok, P, Bradley, R, Jahncke, J, Goericke, R, Campbell, GS, Hildebrand, JA, Melin, SR, Delong, RL, Gomez-Valdes, J, Lavaniegos, B, Gaxiola-Castro, G, Golightly, RT, Schneider, SR, Lo, N, Suryan, RM, Gladics, AJ, Horton, CA, Fisher, J, Morgan, C, Peterson, J, Daly, EA, Auth, TD, and Abell, J
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Fisheries ,Fisheries Sciences - Abstract
This report reviews the state of the California Current System (CCS) between winter 2012 and spring 2013, and includes observations from Washington State to Baja California. During 2012, large-scale climate modes indicated the CCS remained in a cool, productive phase present since 2007. The upwelling season was delayed north of 42°N, but regions to the south, especially 33° to 36°N, experienced average to above average upwelling that persisted throughout the summer. Contrary to the indication of high production suggested by the climate indices, chlorophyll observed from surveys and remote sensing was below average along much of the coast. As well, some members of the forage assemblages along the coast experienced low abundances in 2012 surveys. Specifically, the concentrations of all lifestages observed directly or from egg densities of Pacific sardine, Sardinops sagax, and northern anchovy, Engraulis mordax, were less than previous years’ survey estimates. However, 2013 surveys and observations indicate an increase in abundance of northern anchovy. During winter 2011/2012, the increased presence of northern copepod species off northern California was consistent with stronger southward transport. Krill and small-fraction zooplankton abundances, where examined, were generally above average. North of 42°N, salps returned to typical abundances in 2012 after greater observed concentrations in 2010 and 2011. In contrast, salp abundance off central and southern California increased after a period of southward transport during winter 2011/2012. Reproductive success of piscivorous Brandt’s cormorant, Phalacrocorax penicillatus, was reduced while planktivorous Cassin’s auklet, Ptychoramphus aleuticus was elevated. Differences between the productivity of these two seabirds may be related to the available forage assemblage observed in the surveys. California sea lion pups from San Miguel Island were undernourished resulting in a pup mortality event perhaps in response to changes in forage availability. Limited biological data were available for spring 2013, but strong winter upwelling coastwide indicated an early spring transition, with the strong upwelling persisting into early summer.
- Published
- 2013
5. State of the California current 2009-2010: Regional variation persists through transition from la Niña to el Niño (and back?)
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Bjorkstedt, EP, Goericke, R, McClatchie, S, Weber, E, Watson, W, Lo, N, Peterson, B, Emmett, B, Peterson, J, Durazo, R, Gaxiola-Castro, G, Chavez, F, Pennington, JT, Collins, CA, Field, J, Ralston, S, Sakuma, K, Bograd, SJ, Schwing, FB, Xue, Y, Sydeman, WJ, Thompson, SA, Santora, JA, Largier, J, Halle, C, Morgan, S, Kim, SY, Merkens, KPB, Hildebrand, JA, and Munger, LM
- Subjects
Fisheries ,Fisheries Sciences - Abstract
This report summarizes observations of the California Current System (CCS) from Baja California, Mexico to Oregon for the period from spring 2009 through spring 2010. During this period, changes in the state of the CCS reflected a transition from cool La Niña conditions into and through a short-lived, relatively weak El Niño event. Weaker than normal upwelling and several extended relaxation events contributed to warming over much of the CCS during summer 2009, especially in the north. Moderation of La Niña conditions in the CCS coincided with the development of El Niño conditions in the equatorial Pacific, yet manifested well in advance of any evidence for direct effects of El Niño on the CCS. Responses to El Niño in fall 2009 and winter 2009-2010 appear to have varied substantially with latitude: conditions off southern California returned to near climatological values with the decline of La Niña, and did not indicate any subsequent response to El Niño, yet the northern CCS warmed subtantially following the decline of La Niña and was strongly affected by intense downwelling during winter 2009-2010. The 2009-2010 El Niño diminished rapidly in early 2010, and upwelling off central and southern California resumed unusually early and strongly for a spring following an El Niño, but recovery from El Niño in early 2010 appears to be less robust in the northern CCS. Thus, despite dynamic changes in the overall state of the California Current, 2009-2010 continued the recent pattern of strong regional variability across the CCS.
- Published
- 2010
6. CORRIGENDUM: Trophoscapes of predatory fish reveal biogeographic structuring of spatial dietary overlap and inform fisheries bycatch patterns
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Wells, BK, primary, Santora, JA, additional, Bizzarro, JJ, additional, Billings, A, additional, Brodeur, RD, additional, Daly, EA, additional, Field, JC, additional, Richerson, KE, additional, and Thorson, JT, additional
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- 2023
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7. Trophoscapes of predatory fish reveal biogeographic structuring of spatial dietary overlap and inform fisheries bycatch patterns
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Wells, BK, primary, Santora, JA, additional, Bizzarro, JJ, additional, Billings, A, additional, Brodeur, RD, additional, Daly, EA, additional, Field, JC, additional, Richerson, KE, additional, and Thorson, JT, additional
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- 2023
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8. Diet segregation in Adélie penguins: some individuals attempt to overcome colony-induced and annual foraging challenges
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Massaro, M, primary, Ainley, DG, additional, Santora, JA, additional, Quillfeldt, P, additional, Lescroël, A, additional, Whitehead, A, additional, Varsani, A, additional, Ballard, G, additional, and Lyver P, O’B, additional
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- 2020
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9. Environmental and geographic relationships among salmon forage assemblages along the continental shelf of the California Current
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Friedman, WR, primary, Santora, JA, additional, Schroeder, ID, additional, Huff, DD, additional, Brodeur, RD, additional, Field, JC, additional, and Wells, BK, additional
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- 2018
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10. Timing of sea-ice retreat affects the distribution of seabirds and their prey in the southeastern Bering Sea
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Hunt, GL, primary, Renner, M, additional, Kuletz, KJ, additional, Salo, S, additional, Eisner, L, additional, Ressler, PH, additional, Ladd, C, additional, and Santora, JA, additional
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- 2018
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11. Impacts of ocean climate variability on biodiversity of pelagic forage species in an upwelling ecosystem
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Santora, JA, primary, Hazen, EL, additional, Schroeder, ID, additional, Bograd, SJ, additional, Sakuma, KM, additional, and Field, JC, additional
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- 2017
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12. Overwinter habitat selection by Antarctic krill under varying sea-ice conditions: implications for top predators and fishery management
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Reiss, CS, primary, Cossio, A, additional, Santora, JA, additional, Dietrich, KS, additional, Murray, A, additional, Mitchell, BG, additional, Walsh, J, additional, Weiss, EL, additional, Gimpel, C, additional, Jones, CD, additional, and Watters, GM, additional
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- 2017
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13. Marine ecosystem perspectives on Chinook salmon recruitment: a synthesis of empirical and modeling studies from a California upwelling system
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Wells, BK, primary, Santora, JA, additional, Schroeder, ID, additional, Mantua, N, additional, Sydeman, WJ, additional, Huff, DD, additional, and Field, JC, additional
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- 2016
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14. More than passive drifters: a stochastic dynamic model for the movement of Antarctic krill
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Richerson, K, primary, Watters, GM, additional, Santora, JA, additional, Schroeder, ID, additional, and Mangel, M, additional
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- 2015
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15. Modeling krill aggregations in the central-northern California Current
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Dorman, JG, primary, Sydeman, WJ, additional, García-Reyes, M, additional, Zeno, RA, additional, and Santora, JA, additional
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- 2015
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16. Spatio-temporal persistence of top predator hotspots near the Antarctic Peninsula
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Santora, JA, primary and Veit, RR, additional
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- 2013
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17. Scales and mechanisms of marine hotspot formation
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Hazen, EL, primary, Suryan, RM, additional, Santora, JA, additional, Bograd, SJ, additional, Watanuki, Y, additional, and Wilson, RP, additional
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- 2013
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18. Water and otolith chemistry identify exposure of juvenile rockfish to upwelled waters in an open coastal system
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Woodson, LE, primary, Wells, BK, additional, Grimes, CB, additional, Franks, RP, additional, Santora, JA, additional, and Carr, MH, additional
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- 2013
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19. Population dynamics of Chinook salmon Oncorhynchus tshawytscha relative to prey availability in the central California coastal region
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Wells, BK, primary, Santora, JA, additional, Field, JC, additional, MacFarlane, RB, additional, Marinovic, BB, additional, and Sydeman, WJ, additional
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- 2012
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20. Effects of climate variability on breeding phenology and performance of tropical seabirds in the eastern Indian Ocean
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Surman, CA, primary, Nicholson, LW, additional, and Santora, JA, additional
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- 2012
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21. Phenology of pelagic seabird abundance relative to marine climate change in the Alaska Gyre
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Thompson, SA, primary, Sydeman, WJ, additional, Santora, JA, additional, Morgan, KH, additional, Crawford, W, additional, and Burrows, MT, additional
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- 2012
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22. New approach for using remotely sensed chlorophyll a to identify seabird hotspots
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Suryan, RM, primary, Santora, JA, additional, and Sydeman, WJ, additional
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- 2012
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23. Spatial association between hotspots of baleen whales and demographic patterns of Antarctic krill Euphausia superba suggests size-dependent predation
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Santora, JA, primary, Reiss, CS, additional, Loeb, VJ, additional, and Veit, RR, additional
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- 2010
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24. Ecological forecasts for marine resource management during climate extremes.
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Brodie S, Pozo Buil M, Welch H, Bograd SJ, Hazen EL, Santora JA, Seary R, Schroeder ID, and Jacox MG
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- Humans, Weather, Temperature, Forecasting, Climate Change, Ecosystem, Climate
- Abstract
Forecasting weather has become commonplace, but as society faces novel and uncertain environmental conditions there is a critical need to forecast ecology. Forewarning of ecosystem conditions during climate extremes can support proactive decision-making, yet applications of ecological forecasts are still limited. We showcase the capacity for existing marine management tools to transition to a forecasting configuration and provide skilful ecological forecasts up to 12 months in advance. The management tools use ocean temperature anomalies to help mitigate whale entanglements and sea turtle bycatch, and we show that forecasts can forewarn of human-wildlife interactions caused by unprecedented climate extremes. We further show that regionally downscaled forecasts are not a necessity for ecological forecasting and can be less skilful than global forecasts if they have fewer ensemble members. Our results highlight capacity for ecological forecasts to be explored for regions without the infrastructure or capacity to regionally downscale, ultimately helping to improve marine resource management and climate adaptation globally., (© 2023. The Author(s).)
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- 2023
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25. A multi-predator trophic database for the California Current Large Marine Ecosystem.
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Bizzarro JJ, Dewitt L, Wells BK, Curtis KA, Santora JA, and Field JC
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- Animals, Mammals, Nutritional Status, California, Ecosystem, Fishes
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The California Current Trophic Database (CCTD) was developed at NOAA Southwest Fisheries Science Center in collaboration with numerous diet data contributors. We compiled the CCTD from twenty-four data sets, representing both systematic collections and directed trophic studies. Diet composition data, including stomach and scat samples, were obtained from 105,694 individual predators among 143 taxa collected throughout the California Current Large Marine Ecosystem (CCLME) from 1967-2019. Predator taxa consist of squids (n = 5), elasmobranchs (n = 13), bony fishes (n = 118), and marine mammals (n = 7). Extensive time series are available for some predators (e.g., California Sea Lion, Pacific Hake, Chinook Salmon). The CCTD represents the largest compilation of raw trophic data within the CCLME, allowing for more refined analyses and modeling studies within this region. Our intention is to further augment and periodically update the dataset as additional historical or contemporary data become available to increase its utility and impact., (© 2023. The Author(s).)
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- 2023
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26. Multiscale relationships between humpback whales and forage species hotspots within a large marine ecosystem.
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Szesciorka AR, Demer DA, Santora JA, Forney KA, and Moore JE
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- Animals, Seasons, Biomass, British Columbia, Fishes, Ecosystem, Humpback Whale
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Fluctuations in prey abundance, composition, and distribution can impact predators, and when predators and fisheries target the same species, predators become essential to ecosystem-based management. Because of the difficulty in collecting concomitant predator-prey data at appropriate scales in patchy environments, few studies have identified strong linkages between cetaceans and prey, especially across large geographic areas. During summer 2018, a line-transect survey for cetaceans and coastal pelagic species was conducted over the continental shelf and slope of British Columbia, Canada, and the US West Coast, allowing for a large-scale investigation of predator-prey spatial relationships. We report on a case study of humpback whales (Megaptera novaeangliae) and their primary prey-Pacific herring (Clupea pallasii), northern anchovy (Engraulis mordax), and krill-using generalized additive models to explore the relationships between whale abundance on 10-km transect segments and prey metrics. Prey metrics included direct measures of biomass densities on segments and an original hotspot metric. For each prey species, segments in the upper fifth percentile for biomass density (across all segments) were designated hotspots, and whale counts on a segment were evaluated for their relationship to number of hotspot segments (species-specific and multispecies) within 25, 50, or 100 km. Whale abundance was not strongly related to direct measures of biomass densities, whereas models using hotspot metrics were more effective at describing variation in whale abundance, underscoring that evaluating prey at relevant and measurable scales is critical in patchy, dynamic marine environments. Our analysis highlighted differences in the distribution and prey availability for three humpback whale distinct population segments (DPSs) as defined under the US Endangered Species Act, including threatened and endangered DPSs that forage within the California Current Large Marine Ecosystem. These linkages provide insights into which prey species whales may be targeting in different regions and across multiple scales and, consequently, how climatic variability and anthropogenic risks may differentially impact these distinct predator-prey assemblages. By identifying scale-appropriate prey hotspots that co-occur with humpback whale aggregations, and with targeted, consistent prey sampling and estimations of potential consumption rates by whales, these findings can help inform the conservation and management of humpback whales within an ecosystem-based management framework., (© 2022 The Ecological Society of America.)
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- 2023
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27. An anchovy ecosystem indicator of marine predator foraging and reproduction.
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Fennie HW, Seary R, Muhling BA, Bograd SJ, Brodie S, Cimino MA, Hazen EL, Jacox MG, McHuron EA, Melin S, Santora JA, Suca JJ, Thayer JA, Thompson AR, Warzybok P, and Tommasi D
- Subjects
- Animals, Food Chain, Birds, Fishes, Reproduction, Ecosystem, Charadriiformes
- Abstract
Forage fishes are key energy conduits that transfer primary and secondary productivity to higher trophic levels. As novel environmental conditions caused by climate change alter ecosystems and predator-prey dynamics, there is a critical need to understand how forage fish control bottom-up forcing of food web dynamics. In the northeast Pacific, northern anchovy ( Engraulis mordax ) is an important forage species with high interannual variability in population size that subsequently impacts the foraging and reproductive ecology of marine predators. Anchovy habitat suitability from a species distribution model (SDM) was assessed as an indicator of the diet, distribution and reproduction of four predator species. Across 22 years (1998-2019), this anchovy ecosystem indicator (AEI) was significantly positively correlated with diet composition of all species and the distribution of common murres ( Uria aalge ), Brandt's cormorants ( Phalacrocorax penicillatus ) and California sea lions ( Zalophus californianus ), but not rhinoceros auklets ( Cerorhinca monocerata ). The capacity for the AEI to explain variability in predator reproduction varied by species but was strongest with cormorants and sea lions. The AEI demonstrates the utility of forage SDMs in creating ecosystem indicators to guide ecosystem-based management.
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- 2023
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28. Revenue loss due to whale entanglement mitigation and fishery closures.
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Seary R, Santora JA, Tommasi D, Thompson A, Bograd SJ, Richerson K, Brodie S, and Holland D
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- Animals, Whales, Ecosystem, Retrospective Studies, Seasons, Conservation of Natural Resources methods, Fisheries, Brachyura
- Abstract
Whale entanglements with fishing gear, exacerbated by changing environmental conditions, pose significant risk to whale populations. Management tools used to reduce entanglement risk, for example temporary area restrictions on fishing, can have negative economic consequences for fishing communities. Balancing whale protection with sustaining productive fisheries is therefore a challenge experienced worldwide. In the California Current Ecosystem, ecosystem indicators have been used to understand the environmental dynamics that lead to increased whale entanglement risk in a lucrative crab fishery. However, an assessment of socio-economic risk for this fishery, as in many other regions, is missing. We estimate retrospectively the losses from ex-vessel revenue experienced by commercial Dungeness crab fishers in California during two seasons subject to whale entanglement mitigation measures using a Linear-Cragg hurdle modeling approach which incorporated estimates of pre-season crab abundance. In the 2020 fishing season, our results suggest total revenues would have been $14.4 million higher in the Central Management Area of California in the absence of closures and other disturbances. In the 2019 fishing season, our results suggest ex-vessel revenues would have been $9.4 million higher in the Central Management Area and $0.3 million higher in the Northern Management Area. Our evaluation should motivate the development of strategies which maximize whale protection whilst promoting productive, sustainable and economically-viable fisheries., (© 2022. The Author(s).)
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- 2022
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29. Diverse integrated ecosystem approach overcomes pandemic-related fisheries monitoring challenges.
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Santora JA, Rogers TL, Cimino MA, Sakuma KM, Hanson KD, Dick EJ, Jahncke J, Warzybok P, and Field JC
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- Animals, Biodiversity, COVID-19 transmission, COVID-19 virology, Databases, Factual, Ecosystem, Environmental Monitoring methods, Fishes, Food Chain, Models, Statistical, SARS-CoV-2 isolation & purification, COVID-19 epidemiology, Conservation of Natural Resources methods, Fisheries statistics & numerical data, SARS-CoV-2 pathogenicity
- Abstract
The COVID-19 pandemic caused unprecedented cancellations of fisheries and ecosystem-assessment surveys, resulting in a recession of observations needed for management and conservation globally. This unavoidable reduction of survey data poses challenges for informing biodiversity and ecosystem functioning, developing future stock assessments of harvested species, and providing strategic advice for ecosystem-based management. We present a diversified framework involving integration of monitoring data with empirical models and simulations to inform ecosystem status within the California Current Large Marine Ecosystem. We augment trawl observations collected from a limited fisheries survey with survey effort reduction simulations, use of seabird diets as indicators of fish abundance, and krill species distribution modeling trained on past observations. This diversified approach allows for evaluation of ecosystem status during data-poor situations, especially during the COVID-19 era. The challenges to ecosystem monitoring imposed by the pandemic may be overcome by preparing for unexpected effort reduction, linking disparate ecosystem indicators, and applying new species modeling techniques., (© 2021. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)
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- 2021
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30. Spatiotemporal patterns of variability in the abundance and distribution of winter-spawned pelagic juvenile rockfish in the California Current.
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Field JC, Miller RR, Santora JA, Tolimieri N, Haltuch MA, Brodeur RD, Auth TD, Dick EJ, Monk MH, Sakuma KM, and Wells BK
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- Animals, California, Conservation of Natural Resources statistics & numerical data, Food Chain, Spatio-Temporal Analysis, Animal Distribution, Ecological Parameter Monitoring statistics & numerical data, Fisheries statistics & numerical data, Perciformes physiology, Seasons
- Abstract
Rockfish are an important component of West Coast fisheries and California Current food webs, and recruitment (cohort strength) for rockfish populations has long been characterized as highly variable for most studied populations. Research efforts and fisheries surveys have long sought to provide greater insights on both the environmental drivers, and the fisheries and ecosystem consequences, of this variability. Here, variability in the temporal and spatial abundance and distribution patterns of young-of-the-year (YOY) rockfishes are described based on midwater trawl surveys conducted throughout the coastal waters of California Current between 2001 and 2019. Results confirm that the abundance of winter-spawning rockfish taxa in particular is highly variable over space and time. Although there is considerable spatial coherence in these relative abundance patterns, there are many years in which abundance patterns are very heterogeneous over the scale of the California Current. Results also confirm that the high abundance levels of YOY rockfish observed during the 2014-2016 large marine heatwave were largely coastwide events. Species association patterns of pelagic YOY for over 20 rockfish taxa in space and time are also described. The overall results will help inform future fisheries-independent surveys, and will improve future indices of recruitment strength used to inform stock assessment models and marine ecosystem status reports., Competing Interests: The authors have declared that no competing interests exist.
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- 2021
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31. Acute bottlenecks to the survival of juvenile Pygoscelis penguins occur immediately after fledging.
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Hinke JT, Watters GM, Reiss CS, Santora JA, and Santos MM
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- Animals, Antarctic Regions, Spheniscidae
- Abstract
Estimating when and where survival bottlenecks occur in free-ranging marine predators is critical for effective demographic monitoring and spatial planning. This is particularly relevant to juvenile stages of long-lived species for which direct observations of death are typically not possible. We used satellite telemetry data from fledgling Adélie, chinstrap and gentoo penguins near the Antarctic Peninsula to estimate the spatio-temporal scale of a bottleneck after fledging. Fledglings were tracked up to 106 days over distances of up to 2140 km. Cumulative losses of tags increased to 73% within 16 days of deployment, followed by an order-of-magnitude reduction in loss rates thereafter. The timing and location of tag losses were consistent with at-sea observations of penguin carcasses and bioenergetics simulations of mass loss to thresholds associated with low recruitment probability. A bootstrapping procedure is used to assess tag loss owing to death versus other factors. Results suggest insensitivity in the timing of the bottleneck and quantify plausible ranges of mortality rates within the bottleneck. The weight of evidence indicates that a survival bottleneck for fledgling penguins is acute, attributable to predation and starvation, and may account for at least 33% of juvenile mortality.
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- 2020
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32. Krill Hotspot Formation and Phenology in the California Current Ecosystem.
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Fiechter J, Santora JA, Chavez F, Northcott D, and Messié M
- Abstract
In the California Current Ecosystem, krill represent a key link between primary production and higher trophic level species owing to their central position in the food web and tendency to form dense aggregations. However, the strongly advective circulation associated with coastal upwelling may decouple the timing, occurrence, and persistence of krill hotspots from phytoplankton biomass and nutrient sources. Results from a coupled physical-biological model provide insights into fundamental mechanisms controlling the phenology of krill hotspots in the California Current Ecosystem, and their sensitivity to alongshore changes in coastal upwelling intensity. The simulation indicates that dynamics controlling krill hotspot formation, intensity, and persistence on seasonal and interannual timescales are strongly heterogeneous and related to alongshore variations in upwelling-favorable winds, primary production, and ocean currents. Furthermore, regions promoting persistent krill hotspot formation coincide with increased observed abundance of top predators, indicating that the model resolves important ecosystem complexity and function., (©2020. The Authors.)
- Published
- 2020
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33. Habitat compression and ecosystem shifts as potential links between marine heatwave and record whale entanglements.
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Santora JA, Mantua NJ, Schroeder ID, Field JC, Hazen EL, Bograd SJ, Sydeman WJ, Wells BK, Calambokidis J, Saez L, Lawson D, and Forney KA
- Subjects
- Animals, Biodiversity, Conservation of Natural Resources, Ecosystem, Homing Behavior, Hot Temperature, Humpback Whale injuries, Population Density, Behavior, Animal, Climate Change, Humpback Whale physiology
- Abstract
Climate change and increased variability and intensity of climate events, in combination with recovering protected species populations and highly capitalized fisheries, are posing new challenges for fisheries management. We examine socio-ecological features of the unprecedented 2014-2016 northeast Pacific marine heatwave to understand the potential causes for record numbers of whale entanglements in the central California Current crab fishery. We observed habitat compression of coastal upwelling, changes in availability of forage species (krill and anchovy), and shoreward distribution shift of foraging whales. We propose that these ecosystem changes, combined with recovering whale populations, contributed to the exacerbation of entanglements throughout the marine heatwave. In 2016, domoic acid contamination prompted an unprecedented delay in the opening of California's Dungeness crab fishery that inadvertently intensified the spatial overlap between whales and crab fishery gear. We present a retroactive assessment of entanglements to demonstrate that cooperation of fishers, resource managers, and scientists could mitigate future entanglement risk by developing climate-ready fisheries approaches, while supporting thriving fishing communities.
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- 2020
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34. Humpback whale song occurrence reflects ecosystem variability in feeding and migratory habitat of the northeast Pacific.
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Ryan JP, Cline DE, Joseph JE, Margolina T, Santora JA, Kudela RM, Chavez FP, Pennington JT, Wahl C, Michisaki R, Benoit-Bird K, Forney KA, Stimpert AK, DeVogelaere A, Black N, and Fischer M
- Subjects
- Animals, California, Ecosystem, Population Density, Seasons, Temperature, Animal Migration physiology, Humpback Whale physiology, Vocalization, Animal physiology
- Abstract
This study examines the occurrence of humpback whale (Megaptera novaeangliae) song in the northeast Pacific from three years of continuous recordings off central California (36.713°N, 122.186°W). Song is prevalent in this feeding and migratory habitat, spanning nine months of the year (September-May), peaking in winter (November-January), and reaching a maximum of 86% temporal coverage (during November 2017). From the rise of song in fall through the end of peak occurrence in winter, song length increases significantly from month to month. The seasonal peak in song coincides with the seasonal trough in day length and sighting-based evidence of whales leaving Monterey Bay, consistent with seasonal migration. During the seasonal song peak, diel variation shows maximum occurrence at night (69% of the time), decreasing during dawn and dusk (52%), and further decreasing with increasing solar elevation during the day, reaching a minimum near solar noon (30%). Song occurrence increased 44% and 55% between successive years. Sighting data within the acoustic detection range of the hydrophone indicate that variation in local population density was an unlikely cause of this large interannual variation. Hydrographic data and modeling of acoustic transmission indicate that changes in neither habitat occupancy nor acoustic transmission were probable causes. Conversely, the positive interannual trend in song paralleled major ecosystem variations, including similarly large positive trends in wind-driven upwelling, primary productivity, and krill abundance. Further, the lowest song occurrence during the first year coincided with anomalously warm ocean temperatures and an extremely toxic harmful algal bloom that affected whales and other marine mammals in the region. These major ecosystem variations may have influenced the health and behavior of humpback whales during the study period., Competing Interests: The authors have read the journal's policy and have the following competing interest: MF is the owner of Aguasonic Acoustics. There are no patents, products in development or marketed products to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
- Published
- 2019
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35. Submarine canyons represent an essential habitat network for krill hotspots in a Large Marine Ecosystem.
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Santora JA, Zeno R, Dorman JG, and Sydeman WJ
- Abstract
Submarine canyon systems are ubiquitous features of marine ecosystems, known to support high levels of biodiversity. Canyons may be important to benthic-pelagic ecosystem coupling, but their role in concentrating plankton and structuring pelagic communities is not well known. We hypothesize that at the scale of a large marine ecosystem, canyons provide a critical habitat network, which maintain energy flow and trophic interactions. We evaluate canyon characteristics relative to the distribution and abundance of krill, critically important prey in the California Current Ecosystem. Using a geological database, we conducted a census of canyon locations, evaluated their dimensions, and quantified functional relationships with krill hotspots (i.e., sites of persistently elevated abundance) derived from hydro-acoustic surveys. We found that 76% of krill hotspots occurred within and adjacent to canyons. Most krill hotspots were associated with large shelf-incising canyons. Krill hotspots and canyon dimensions displayed similar coherence as a function of latitude and indicate a potential regional habitat network. The latitudinal migration of many fish, seabirds and mammals may be enhanced by using this canyon-krill network to maintain foraging opportunities. Biogeographic assessments and predictions of krill and krill-predator distributions under climate change may be improved by accounting for canyons in habitat models.
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- 2018
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36. Persistence of trophic hotspots and relation to human impacts within an upwelling marine ecosystem.
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Santora JA, Sydeman WJ, Schroeder ID, Field JC, Miller RR, and Wells BK
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- Animals, California, Ecosystem, Pacific Ocean, Ships, Commerce, Fisheries, Food Chain, Human Activities
- Abstract
Human impacts (e.g., fishing, pollution, and shipping) on pelagic ecosystems are increasing, causing concerns about stresses on marine food webs. Maintaining predator-prey relationships through protection of pelagic hotspots is crucial for conservation and management of living marine resources. Biotic components of pelagic, plankton-based, ecosystems exhibit high variability in abundance in time and space (i.e., extreme patchiness), requiring investigation of persistence of abundance across trophic levels to resolve trophic hotspots. Using a 26-yr record of indicators for primary production, secondary (zooplankton and larval fish), and tertiary (seabirds) consumers, we show distributions of trophic hotspots in the southern California Current Ecosystem result from interactions between a strong upwelling center and a productive retention zone with enhanced nutrients, which concentrate prey and predators across multiple trophic levels. Trophic hotspots also overlap with human impacts, including fisheries extraction of coastal pelagic and groundfish species, as well as intense commercial shipping traffic. Spatial overlap of trophic hotspots with fisheries and shipping increases vulnerability of the ecosystem to localized depletion of forage fish, ship strikes on marine mammals, and pollution. This study represents a critical step toward resolving pelagic areas of high conservation interest for planktonic ecosystems and may serve as a model for other ocean regions where ecosystem-based management and marine spatial planning of pelagic ecosystems is warranted., (© 2016 by the Ecological Society of America.)
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- 2017
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37. Timing of ice retreat alters seabird abundances and distributions in the southeast Bering Sea.
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Renner M, Salo S, Eisner LB, Ressler PH, Ladd C, Kuletz KJ, Santora JA, Piatt JF, Drew GS, and Hunt GL Jr
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- Animals, Arctic Regions, Copepoda, Ecosystem, Euphausiacea, Gadiformes, Pacific Ocean, Zooplankton, Birds physiology, Food Chain, Ice Cover, Seasons
- Abstract
Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer seabird densities and average bathymetry depth distributions between years with early (typically warm) and late (typically cold) ice retreat. Averaged over all seabird species, densities in early-ice-retreat-years were 10.1% (95% CI: 1.1-47.9%) of that in late-ice-retreat-years. In early-ice-retreat-years, surface-foraging species had increased numbers over the middle shelf (50-150 m) and reduced numbers over the shelf slope (200-500 m). Pursuit-diving seabirds showed a less clear trend. Euphausiids and the copepod Calanus marshallae/glacialis were 2.4 and 18.1 times less abundant in early-ice-retreat-years, respectively, whereas age-0 walleye pollock Gadus chalcogrammus near-surface densities were 51× higher in early-ice-retreat-years. Our results suggest a mechanistic understanding of how present and future changes in sea-ice-retreat timing may affect top predators like seabirds in the southeastern Bering Sea., (© 2016 The Author(s).)
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- 2016
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38. A spatially distinct history of the development of california groundfish fisheries.
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Miller RR, Field JC, Santora JA, Schroeder ID, Huff DD, Key M, Pearson DE, and MacCall AD
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- California, Ecosystem, Fish Products economics, Fisheries statistics & numerical data, History, 19th Century, History, 20th Century, History, 21st Century, Fisheries history
- Abstract
During the past century, commercial fisheries have expanded from small vessels fishing in shallow, coastal habitats to a broad suite of vessels and gears that fish virtually every marine habitat on the globe. Understanding how fisheries have developed in space and time is critical for interpreting and managing the response of ecosystems to the effects of fishing, however time series of spatially explicit data are typically rare. Recently, the 1933-1968 portion of the commercial catch dataset from the California Department of Fish and Wildlife was recovered and digitized, completing the full historical series for both commercial and recreational datasets from 1933-2010. These unique datasets include landing estimates at a coarse 10 by 10 minute "grid-block" spatial resolution and extends the entire length of coastal California up to 180 kilometers from shore. In this study, we focus on the catch history of groundfish which were mapped for each grid-block using the year at 50% cumulative catch and total historical catch per habitat area. We then constructed generalized linear models to quantify the relationship between spatiotemporal trends in groundfish catches, distance from ports, depth, percentage of days with wind speed over 15 knots, SST and ocean productivity. Our results indicate that over the history of these fisheries, catches have taken place in increasingly deeper habitat, at a greater distance from ports, and in increasingly inclement weather conditions. Understanding spatial development of groundfish fisheries and catches in California are critical for improving population models and for evaluating whether implicit stock assessment model assumptions of relative homogeneity of fisheries removals over time and space are reasonable. This newly reconstructed catch dataset and analysis provides a comprehensive appreciation for the development of groundfish fisheries with respect to commonly assumed trends of global fisheries patterns that are typically constrained by a lack of long-term spatial datasets.
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- 2014
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39. Spatio-temporal dynamics of ocean conditions and forage taxa reveal regional structuring of seabird–prey relationships.
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Santora JA, Schroeder ID, Field JC, Wells BK, and Sydeman WJ
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- Animals, Pacific Ocean, Population Dynamics, Salinity, Seawater, Temperature, Time Factors, Charadriiformes physiology, Euphausiacea physiology, Fishes physiology, Predatory Behavior physiology
- Abstract
Studies of predator–prey demographic responses and the physical drivers of such relationships are rare, yet essential for predicting future changes in the structure and dynamics of marine ecosystems. Here, we hypothesize that predator–prey relationships vary spatially in association with underlying physical ocean conditions, leading to observable changes in demographic rates, such as reproduction. To test this hypothesis, we quantified spatio-temporal variability in hydrographic conditions, krill, and forage fish to model predator (seabird) demographic responses over 18 years (1990–2007). We used principal component analysis and spatial correlation maps to assess coherence among ocean conditions, krill, and forage fish, and generalized additive models to quantify interannual variability in seabird breeding success relative to prey abundance. The first principal component of four hydrographic measurements yielded an index that partitioned “warm/weak upwelling” and “cool/strong upwelling” years. Partitioning of krill and forage fish time series among shelf and oceanic regions yielded spatially explicit indicators of prey availability. Krill abundance within the oceanic region was remarkably consistent between years, whereas krill over the shelf showed marked interannual fluctuations in relation to ocean conditions. Anchovy abundance varied on the shelf, and was greater in years of strong stratification, weak upwelling and warmer temperatures. Spatio-temporal variability of juvenile forage fish co-varied strongly with each other and with krill, but was weakly correlated with hydrographic conditions. Demographic responses between seabirds and prey availability revealed spatially variable associations indicative of the dynamic nature of “predator–habitat” relationships. Quantification of spatially explicit demographic responses, and their variability through time, demonstrate the possibility of delineating specific critical areas where the implementation of protective measures could maintain functions and productivity of central place foraging predators.
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- 2014
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40. Increasing variance in North Pacific climate relates to unprecedented ecosystem variability off California.
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Sydeman WJ, Santora JA, Thompson SA, Marinovic B, and Di Lorenzo E
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- Animals, Biodiversity, California, Food Chain, Pacific Ocean, Climate Change, Ecosystem
- Abstract
Changes in variance are infrequently examined in climate change ecology. We tested the hypothesis that recent high variability in demographic attributes of salmon and seabirds off California is related to increasing variability in remote, large-scale forcing in the North Pacific operating through changes in local food webs. Linear, indirect numerical responses between krill (primarily Thysanoessa spinifera) and juvenile rockfish abundance (catch per unit effort (CPUE)) explained >80% of the recent variability in the demography of these pelagic predators. We found no relationships between krill and regional upwelling, though a strong connection to the North Pacific Gyre Oscillation (NPGO) index was established. Variance in NPGO and related central Pacific warming index increased after 1985, whereas variance in the canonical ENSO and Pacific Decadal Oscillation did not change. Anthropogenic global warming or natural climate variability may explain recent intensification of the NPGO and its increasing ecological significance. Assessing non-stationarity in atmospheric-environmental interactions and placing greater emphasis on documenting changes in variance of bio-physical systems will enable insight into complex climate-marine ecosystem dynamics., (© 2013 Blackwell Publishing Ltd.)
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- 2013
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41. Medication cart-filling time, accuracy, and cost with an automated dispensing system.
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Klein EG, Santora JA, Pascale PM, and Kitrenos JG
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- Cost-Benefit Analysis, Hospital Bed Capacity, 500 and over, Hospitals, Teaching, Humans, Medication Errors, New York, Pharmacists statistics & numerical data, Pharmacy Service, Hospital economics, Pharmacy Service, Hospital standards, Time and Motion Studies, Automation statistics & numerical data, Medication Systems, Hospital economics, Medication Systems, Hospital standards
- Abstract
Medication cart filling with an automated dispensing system was compared with manual cart filling with respect to personnel time, costs, and accuracy. At a 650-bed tertiary-care medical center, technician cart filling and pharmacist cart checking were timed for the existing manual system and for the Baxter ATC-212 automated dispensing system. Subsequently, carts filled with each system were checked for accuracy of dispensing. On the basis of drugs used in the automated system over three months, drug acquisition and dispensing costs were calculated for automated and manual cart filling; the costs of personnel time were also compared. Daily cart filling time for technicians was significantly less with the automated system. The savings of pharmacist time was not significant; pharmacists had to cut the strip-packaged drugs into individual doses as they checked patients' medications. For both systems, errors were found in fewer than 1% of the doses (0.84% for the manual system and 0.65% for the automated system). Drug costs were higher with the automated system; acquisition prices for the bulk drugs purchased for use in the dispensing machine were higher than the prices of the same products in unit dose packaging. Personnel time saved amounted to less than 0.5 full-time equivalent. With the automated system, overall time savings was not great enough to substantially affect pharmacy operations, and drug costs were higher.
- Published
- 1994
42. Zidovudine update: 1990.
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Morse GD, Lechner JL, Santora JA, and Rozek SL
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- Humans, Zidovudine pharmacokinetics, Zidovudine therapeutic use, Acquired Immunodeficiency Syndrome drug therapy, Zidovudine pharmacology
- Abstract
Zidovudine (ZDV) is the only approved antiviral for the treatment of human immunodeficiency virus infection (HIV) in the U.S. Although newer antivirals have reached Phase II testing, ZDV is now the accepted therapy against which all other agents will be compared. Zidovudine 1500 mg/d was previously prescribed only to adult HIV-infected patients who had developed AIDS or AIDS-related complex (ARC). However, results obtained from recently completed studies indicate that a lower daily dose (500 mg) appears to be equivalent. In addition, ZDV therapy appears to be beneficial to asymptomatic HIV-infected patients with CD4+ counts less than 500/mm3. The toxicity profile of ZDV, previously obtained from patients receiving 1500 mg/d, consisted of either acute (e.g., fever, rash, headache) or chronic (e.g., anemia, neutropenia, myopathy) adverse effects. ZDV pharmacokinetics are variable within and between the different subpopulations of HIV-infected patients who have been studied. Bioavailability ranges from 50 to 70 percent, and values for half-life, total body clearance, and volume of distribution are 1-2 h, 20-40 mL/min/kg, and 1-2 L/kg, respectively. Drug interactions occur primarily between ZDV and other agents that undergo hepatic glucuronidation (e.g., probenecid, sulfamethoxazole) resulting in decreased ZDV clearance. ZDV is currently measured by HPLC, radioimmunoassay and FPIA; however, the role of therapeutic monitoring is currently under investigation. Studies of ZDV therapy in neonates, pediatric patients, patients with resistant isolates of HIV, and HIV-infected patients receiving combined treatment with other reverse transcriptase inhibitors or immunomodulators are ongoing.
- Published
- 1990
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