Downscaling global ocean climate models improves estimates of exposure regimes in coastal environments

Nature Portfolio (Springer Nature) | August 26th, 2020

Climate change is expected to warm, deoxygenate, and acidify ocean waters. Global climate models (GCMs) predict future conditions at large spatial scales, and these pred

Climate change is expected to warm, deoxygenate, and acidify ocean waters. Global climate models (GCMs) predict future conditions at large spatial scales, and these predictions are then often used to parameterize laboratory experiments designed to assess biological and ecological responses to future change. However, nearshore ecosystems are affected by a range of physical processes such as tides, local winds, and surface and internal waves, causing local variability in conditions that often exceeds global climate models. Predictions of future climatic conditions at local scales, the most relevant to ecological responses, are largely lacking. To fill this critical gap, we developed a 2D implementation of the Regional Ocean Modeling System (ROMS) to downscale global climate predictions across all Representative Concentration Pathway (RCP) scenarios to smaller spatial scales, in this case the scale of a temperate reef in the northeastern Pacific. To assess the potential biological impacts of local climate variability, we then used the results from different climate scenarios to estimate how climate change may affect the survival, growth, and fertilization of a representative marine benthic invertebrate, the red abalone Haliotis rufescens, to a highly varying multi-stressor environment. We found that high frequency variability in temperature, dissolved oxygen (DO), and pH increases as pCO2 increases in the atmosphere. Extreme temperature and pH conditions are generally not expected until RCP 4.5 or greater, while frequent exposure to low DO is already occurring. In the nearshore environment simulation, strong RCP scenarios can affect red abalone growth as well as reduce fertilization during extreme conditions when compared to global scale simulations.

Draft finding of no significant impact, 2-Gates Fish Protection Demonstration Project.

U.S. Bureau of Reclamation (USBR) | November 13th, 2009

The proposed Demonstration Project is a 5-year experiment to validate a new delta smelt behavioral model and study the effects of modifying flows in the Sacramento-San Jo

The proposed Demonstration Project is a 5-year experiment to validate a new delta smelt behavioral model and study the effects of modifying flows in the Sacramento-San Joaquin Delta (Delta) to protect delta smelt and other sensitive aquatic species from entrainment in Central Valley Project (CVP) and State Water Project (SWP) export pumps. Research suggests that the pre-spawning migration of adult delta smelt is tied to sediment/suspended particles in the water (turbidity). Temporary gates would be placed across Old River and Connection Slough in the central Delta and operated from December to March to keep turbid water away from the CVP and SWP export pumps, thus keeping adult delta smelt away from the pumps, and in March and June to prevent larvae and juvenile delta smelt from being entrained by the export pumps.

DRERIP Ecosystem Conceptual Model: Chinook Salmon & Steelhead

California Department of Fish and Wildlife (CDFW) | September 4th, 2012

This report constitutes the conceptual model for Chinook and steelhead for the Delta Regional Ecosystem Restoration Implementation Plan (DRERIP). The report describes

This report constitutes the conceptual model for Chinook and steelhead for the Delta Regional Ecosystem Restoration Implementation Plan (DRERIP). The report describes conceptual models, not numerical models, but several important considerations apply to both kinds, especially when they are used for management of living natural resources. First, the proper purpose of models is to help people think, not to think for them. Ignoring this can be disastrous, as exemplified by the current economic crisis. The world of credit default swaps was built on highly sophisticated models that persuaded many intelligent people that the associated risk was negligible, but they failed to recognize that a market based on houses that people could not pay for from their earnings is unsustainable. In short, the most important output of a good conceptual or numerical model is clear thinking. To help people think, the model must be focused on selected features of the world that are thought to be important for the purpose at hand: in this case, management of the Delta. A model that tries to include everything will be too complex to be useful for this purpose. Second, to be useful for management of natural living resources, numerical models must be unrealistic, because our knowledge of such resources is incomplete, and is based on data that includes measurement errors. According to Ludwig‘s paradox, "Effective management models cannot be realistic" (Ludwig 1994:516), because two kinds of uncertainty must be balanced (Figure I-1; see Ch. 14 in Williams (2006) for elaboration of this point). In our view, something similar applies to conceptual models of natural systems: to be useful, they must be simple. A schematic of the wiring in some electronic device is a conceptual model that may be useful as well as complex, but trying to develop a similar schematic of an ecosystem or part of an ecosystem is not useful, because our knowledge of such a system is much less complete than our knowledge of engineered devices, and we have only estimates of the relevant parameters. Finally, reality is too complex to capture with a single model. Eric Lander, a noted geneticist who co-chairs President Obama‘s Council of Advisors on Science and Technology, recently remarked that "You can never capture something like an economy, a genome or an ecosystem with one model or one taxonomy – it all depends on the questions you want to ask." (NY Times, 11/11/08). Models are tools that we use to try to think, and multi-purpose tools generally do nothing well. Therefore, although the complete life cycle of Chinook and steelhead is described here, the parts or aspects of the cycle that we think may be affected by management of the Delta are emphasized, and we try to keep it as simple as possible. More detail on most of the topics described here can be found in Quinn (2005), or in Williams (2006), from which this document draws very heavily.

DRERIP Ecosystem Conceptual Model: Delta Aquatic Foodweb

California Department of Fish and Wildlife (CDFW) | October 3rd, 2008

This model is a stylization of the actual food web dynamics of the Sacramento-San Joaquin Delta, which are highly dynamic. The region itself comprises a variety of habita

This model is a stylization of the actual food web dynamics of the Sacramento-San Joaquin Delta, which are highly dynamic. The region itself comprises a variety of habitats, determined by salinity regimes, residence time, hydrology, benthos and physical structure. These physical parameters, or drivers, determine species composition and trophic relationships. The Delta is a tidal system which is subject to varying water inflow. Because inflow and outflow vary as the result of anthropogenic alterations and water management needs, habitats are not static. Rather they are subject to hourly, daily, seasonal and inter-annual variation, and different organisms respond in different ways to these time scales, depending upon their own life histories. Thus salinity and temperature regimes may create different outcomes from food web interactions, based upon how species distributional and recruitment patterns overlap. In general, food web linkages are not static or linear. Organisms switch feeding strategies opportunistically, and these patterns of variability in feeding strategy tend to increase with trophic level. Many organisms, particularly plankton, undergo many generations in the course of a year, and selective forces may allow for rapid evolution which can alter habitat preferences or other life history characteristics. The Delta food web is further dynamic in that new species are regularly introduced into the Estuary, competing with, replacing, or preying upon other organisms. For example, the overbite clam, Corbula amurensis, was introduced in 1986, precipitating a cascade of changes that are still not wholly understood. Zebra and quagga mussels are expected to invade the Delta within the next few years, and will bring further changes. The topology of a food web model will be necessarily complex given these factors. Even without such variability, the potential linkages create a spider web of relationships that is difficult if not impossible to disentangle. In order to create a working model of the Delta food web that is useful for education, for hypothesis?generation, and for management decision?making, it is necessary to create limits to what linkages will be examined. In order to do this, this Delta food web model focuses on organisms that supply food for fish. This is particularly important given the recent concern for pelagic organism decline, which is described mostly for fishes, some of which are listed as endangered or threatened. A key assumption is that fish are integrators of ecosystem function. Also included in the model are invasive organisms that have a large impact on food web dynamics (such as C. amurensis), as are organisms that are particularly abundant (such as the copepod Limnoithona tetraspina), whether or not they are used directly by fish.

DRERIP Ecosystem Conceptual Model: Fish Habitat Linkages

California Department of Fish and Wildlife (CDFW) | January 19th, 2008

The Delta Regional Ecosystem Restoration Implementation Plan (DRERIP) is one of four regional plans intended to guide the implementation of the CALFED Ecosystem Restorati

The Delta Regional Ecosystem Restoration Implementation Plan (DRERIP) is one of four regional plans intended to guide the implementation of the CALFED Ecosystem Restoration Program (ERP) element. The DRERIP will refine the planning foundation for the Delta, develop and refine specific restoration actions and provide project implementation guidance, program tracking, performance evaluation and adaptive management feedback specific to the Delta. The DRERIP Fish Habitat Linkage Model (FHL model) provides a roadmap for how the various conceptual models designed for the DRERIP process intertwine to define fish habitat and ultimately produce fish. The model identifies the key linkages between hydrology and numerous other components of fish habitat. The FHL model shows that hydrodynamics and water operations exert influences on fish recruitment by directly influencing transport fates, the water quality components of habitat, and some biotic interactions. The water quality components of habitat interact with structural components of habitat; their interaction affects the strength of biotic interactions (Peterson 2003). Because the FHL model is a generalized model serving as a template or road map, the relative importance of drivers and linkages, and their direction of impact (positive or negative), are not shown in the model diagram because they will depend on which species, contingent (sensu Secor 1999), or life stage is being evaluated. Additional general descriptions of the state of knowledge about these linkages are provided in the text boxes for each model component.

DRERIP Ecosystem Conceptual Model: Green sturgeon

California Department of Fish and Wildlife (CDFW) | December 27th, 2008

The purpose of this report is to develop a conceptual life history model of North American green sturgeon (Acipenser medirostris) and the factors that affect reproduction

The purpose of this report is to develop a conceptual life history model of North American green sturgeon (Acipenser medirostris) and the factors that affect reproduction, growth, and survival in the Sacramento and San Joaquin rivers and San Francisco Bay-Delta. This model can be used to organize, visualize, and evaluate how the complex life history of green sturgeon relates to the spatial and temporal variability of riverine and estuarine ecosystems and potential consequences of ecosystem restoration and water management alternatives. This model is compatible with the suite of environmental and species models developed by the Department of Fish and Game Ecosystem Restoration Program (ERP) to assess and prioritize proposed restoration actions for the Delta. The model has a geographic emphasis on the Sacramento River and Bay-Delta regions, though the entire distribution of green sturgeon must be considered when population level responses are of concern, due to the unique, highly-migratory life history of this species. The conceptual life history model incorporates information from numerous sources about green sturgeon, often relying upon life history information from populations outside the Southern Distinct Population Segment (DPS) and occasionally considering information from the sympatric white sturgeon (A. transmontanus). While surrogate information from other North American sturgeon could have been used in the model, the distinctive anadromous and ecological characteristics of green sturgeon limited the utility of these species’ information. Due to the limits of quantitative information about green sturgeon, this model is presented in a qualitative narrative with numerical information provided, when available. While it will not provide quantitative limits on species take relative to maintaining a stable population size, it could be further developed into a population forecasting model since it divides the life history into life history stages, transition probabilities, and factors whose affects on reproduction and survival could be quantified. Life history stage transitions are visualized in a series of life stage submodels highlighting the processes and relationships among ecological factors influencing the transition between stages (Figures 1 and 2). A complex set of conditions and processes are necessary to determine whether an individual fish completes the transition from one life stage to the next. Our knowledge of green sturgeon life history remains limited as to the relative importance of biotic and abiotic factors critical for maintaining self-sustaining populations of green sturgeon. Thus, the importance, predictability, and understanding of each of these linkages are identified in the model. Lastly, a similar characterization of independent stressors is undertaken to describe potential factors affecting survival during each life history stage in a known geographic region. This model is dynamic and not intended to be a final version. As new information becomes available, the model should be refined so managers and biologists have the most current information available.

DRERIP Ecosystem Conceptual Model: White sturgeon

California Department of Fish and Wildlife (CDFW) | April 25th, 2011

The purpose of this report is to develop a conceptual life history model of white sturgeon (Acipenser transmontanus) and the factors that affect reproduction, growth, and

The purpose of this report is to develop a conceptual life history model of white sturgeon (Acipenser transmontanus) and the factors that affect reproduction, growth, and survival in the Sacramento-San Joaquin Rivers and San Francisco bay-delta. This model can be used to organize, visualize, and evaluate how the complex life history of white sturgeon relates to the spatial and temporal variability of riverine and estuarine ecosystems and potential consequences of ecosystem restoration and water management alternatives. This model is compatible with the suite of environmental and species models developed by the Department of Fish and Game Ecosystem Restoration Program (ERP) to assess and prioritize proposed restoration actions for the delta. The model has a geographic emphasis on the Sacramento River and bay-delta regions, though the entire distribution of white sturgeon should be considered when population level responses are of concern, due to the migratory life history of this species. The conceptual life history model incorporates information from numerous sources about white sturgeon, often relying upon life history information from populations outside California. While additional surrogate information from other North American sturgeons could have been used in the model, the distinctive diadromous and ecological characteristics of California white sturgeon limited the utility of these species’ information, thus information from other diadromous sturgeon species is only occasionally considered. Due to the limits of quantitative information about white sturgeon, this model is presented in a qualitative narrative, though numerical information is provided when available. While it will not provide quantitative limits on species take relative to maintaining a stable population size, it could be further developed into a population forecasting model since it divides the life history into life history stages, transition probabilities, and factors whose effects on reproduction and survival could be quantified. Life history stage transitions are visualized in a series of life stage submodels highlighting the processes and relationships among ecological factors influencing the transition between stages (Figures 1 and 2). A complex set of conditions and processes are necessary to determine whether an individual white sturgeon completes the transition from one life stage to the next. Our knowledge of how biotic and abiotic factors are critical for maintaining healthy populations is fairly basic. Thus, the importance, predictability, and understanding of each of these linkages are identified in the model. Lastly, a similar characterization of independent stressors is undertaken to describe potential factors affecting survival during each life history stage in a known geographic region. This model is dynamic and not intended to be a final version. As new data become available, the model should be refined so managers and biologists have the most current information available.

Dry Me a River: Ecological Effects of Drought in the Upper San Francisco Estuary

University of California, Davis (UC Davis) | May 24th, 2024

Ecological forecasts for marine resource management during climate extremes

Nature Portfolio (Springer Nature) | December 5th, 2023

Ecological Studies of the Sacramento-San Joaquin Estuary, A Decennial Report 1961-1971

California Department of Fish and Wildlife (CDFW) | June 15th, 1972