Research

Aquatic Ecosystems and Fisheries

Key Findings

In its research on the relationship between climate and Pacific Northwest (PNW) aquatic ecosystems, the Climate Impacts Group (CIG) has:

Salmon MALBEC: A North Pacific-scale study to Support Conservation Planning for Pacific Salmon

• The Model for Assessing Links Between Ecosystems (MALBEC) is a scenario-based tool. The user can manipulate the potential impacts of such factors as climate change, harvest policies, hatchery policies, and freshwater habitat capacity changes on salmon at the North Pacific scale. Results indicate that for any level of ocean productivity, the ocean will only support a certain biomass of fish (Figure 1) but that this biomass could consist of different combinations of stocks, stock numbers and individual fish size. (Mantua et al. 2007)

Climate Change Impacts on Key Aspects of Freshwater Salmon Habitat in Washington State

• Simulations predict rising water temperatures will thermally stress salmon throughout Washington’s watersheds, becoming increasingly severe later in the 21st century(Figure 2). Historically transient runoff watersheds will shift towards rainfall dominant behavior, undergoing more severe summer low flow periods and more frequent days with intense winter flooding. The combined effects of warming stream temperatures and altered streamflows will likely reduce the reproductive success for many Washington salmon populations, with impacts varying for different life history-types and watershed-types. (Mantua et al. (In press))

Defining spring transition: Regional indices for the California Current

• This project investigated the potential to use methods applied to track northern regions of the California Current System (CCS) could be used to trace the southern reaches of the phenomenon. Results indicate that while dramatic changes in wind-derived upwelling and coastal sea levels consistently indicate spring transition in the northern CCS, this is not the case for central and southern regions. Spring transition may be better represented by the rate of change in sea levels and/or changes in spatial patterns of sea surface temperatures. (Holt and Mantua 2009)

Recent trends in paralytic shellfish toxins in Puget Sound, relationships to climate, and capacity for prediction of toxic events

• Blue mussel toxicity is highly variable, but typically exceeds the regulatory limit for human consumption from July to November annually, with most closures occurring early in fall. Case studies of daily variations in local environmental factors leading up to exceptionally toxic events identify a combination of conditions that generally precedes most closures from 1993 to 2007. Using long-term monitoring data, we show that periods of warm air and water temperatures and low streamflow on sub-seasonal timescales may facilitate toxin accumulation in mussels. Significant correlations between annual indices of mussel toxicity and local and large-scale climatic variables did not arise. (Moore et al. 2008)

Local and large-scale climate forcing of Puget Sound oceanographic properties on seasonal to interdecadal timescales

• Two key parameters influence water temperature and salinity profiles in the Puget Sound: local surface air temperatures and freshwater inflows from major river basins. The variability of sea surface temperature and salinity are also dependant on winter patterns of the Aleutian Low, El Niño/Southern Oscillation and the Pacific Decadal Oscillation (Figure 3), all of which can persist for three seasons or reappear the following year. The correlations with large-scale climate variations proved weaker than those that occur on a more local level.(Moore et al. 2008)