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Spatial structure of water-quality impacts and foraging opportunities for steelhead in the Russian River Estuary : an energetics perspective
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2017
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Series: NOAA-TM-NMFS-SWFSC ; 569
[PDF-1.79 MB]
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Description:Estuaries along the California coast are recognized as critical rearing habitat for juvenile salmonids, particularly because they provide abundant feeding opportunities that support rapid growth. However, these estuaries exhibit a high degree of spatial and temporal variability in both food availability and elements of risk such as predation risk and mediocre water quality, varying greatly in response to natural seasonal changes as well as anthropogenic effects and management. Physical models such as a quantified conceptual model (QCM) developed by UC Davis for the Russian River Estuary can be used to predict the spatially explicit response of Estuary water quality and quantity to seasonal change and management interventions. These predictions take the form of depth-profiles of temperature, dissolved oxygen and salinity throughout the Estuary, calibrated to sonde measurements collected as part of regular monitoring. To aid in the interpretation of the outputs of such models, here we synthesize a categorical rating scheme for how water quality and spatial location in the Estuary affects rearing steelhead in terms of foraging opportunity, predation risk, and physiological impacts of water quality. We adopt a bioenergetics perspective as a conceptual framework because energy provides a unifying framework for thinking about how behavioral and physiological responses to predation risk, water quality, and foraging opportunity translate to somatic growth of rearing salmonids. However, our review and synthesis indicates that the tradeoffs posed to rearing salmonids by an estuary among foraging opportunities and the different dimensions of water quality impacts, for example is multidimensional and complex. Rather than propose explicit quantitative models of behavior and physiology that capture all this complexity which is outside our scope and in any case requires further work for simplicity we develop a categorical (or qualitative) scheme to make sense of this complexity. It is our hope that this scheme will aid fisheries managers in interpreting the complex output of physical estuary models, and point the way toward more focused development of coupled behavioral-bioenergetics models of salmonids rearing in estuaries. Such models will need to address the spatial and temporal structure of the tradeoffs, as well as the important role of induced physiological tolerance for salinity and possibly hypoxic conditions, and its relationship to strategies for feeding, growth efficiency, and predator avoidance. For convenience the qualitative rating scheme is summarized in a short appendix at the end of the text. [doi:10.7289/V5/TM-SWFSC-569 (https://doi.org/10.7289/V5/TM-SWFSC-569)]
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Content Notes:David Boughton, Joshua Fuller, Gregg Horton3 , Eric Larson, William Matsubu, and Charles Simenstad.
"January 2017."
System requirements: Adobe Acrobat Reader.
Includes bibliographical references (pages 28-34).
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Rights Information:Public Domain
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