In Canada three specific modeling efforts have been carried out:
Environmental productivity of the Salish Sea: trends, impacts and projections
Team: Dr. Villy Christensen, UBC, Dr. Carl Walters , Dr. Vijay Kumar, Greig Oldford
The Salish Sea Marine Survival Project has compiled a vast amount of data sources, and made clear the need to understand how the environmental productivity of the area has changed temporally and spatially over the last number of decades where there have been substantial changes in the marine survival of key salmon species. While previous studies have evaluated short-term productivity patterns for the Salish Sea, there has so far only been correlative studies to evaluate the relationship between long-term changes in environmental productivity and the productivity of higher trophic levels organisms (notably salmon) in the ecosystem. Through this initiative, Dr. Christensen and his team intend to develop a coupled hydrographic and biogeochemical model of the Salish Sea, and link this to a spatial food web model in order to evaluate how the combination of changes in environmental productivity, food web structure and human impacts (notably through fishing) has changed in the Salish Sea over recent decades.
The overarching hypothesis is that the environmental productivity of the Salish Sea is changing over time (e.g., inter-decadal) and that such changes can be amplified through the food web, potentially leading to stronger effects on upper-trophic level species, such as notably Chinook and coho salmon.
The group beleives that the only practical way to evaluate how environmental productivity is impacting biological productivity over long time spans is through modelling, i.e. data assimilation of large quantities of environmental, biological, ecological and fisheries data). They also believe that the best method is to use a combination of hydrographic, biogeochemical and food web models, and that spatial patterns in productivity in the Salish Sea are important enough to warrant an explicit spatial dimension to the analysis.
Rather than evaluate this using indirect environmental or climate indicators, (e.g., PDO, wind at YVR), they will,
- seek to explain why the environmental productivity is varying,
- evaluate the spatial patterns of productivity over time,
- quantify how the changes propagate through the food web, and
- evaluate how anthropogenic impacts (notably through fishing) have interacted with environmental productivity changes and food web effects over time to impact population trends for notably Chinook and coho salmon in the Salish Sea
- evaluate alternative management scenarios in coordination with the Atlantis modelling group for Puget Sound.
The project was initiated in 2017, and a post-doctoral fellow, Dr Vijay Kumar began work at UBC. The initial hydrodynamic (GETM) and biogeochemical (FABM) models were developed by Drs. Bolding & Bruggeman in connection with a two-week workshop at UBC in September 2017. Vijay was quickly able to run the GETM model with three resolutions, 0.5 km, 1 km and 2 km. Next steps will include implementation of river flow and meteorology in the GETM model. Preparations for the food web model (spatial EwE) was developed during the autumn and winter, and key aspects have been prepared for PhD student Greig Oldford’s start in 2018. An initial version of an individual based model (IBM) to explore smolt survival as a function of predator abundance (initially with seals) was developed and applied. The IBM model will be developed further as part of the project, notably with additional predator layers being added
Spatial and Temporal Variability of Primary and Secondary Production in the Salish Sea from a Coupled Model (SalishSeaCast with SMELT)
Team: Dr. Susan Allen, UBC, Dr. Elise Olson (post-doc)
Under the NSERC Network of Centres of Excellence MEOPAR (Marine Environment Observation, Prediction And Response) Susan Allen and her team have configured a coupled bio-physics model for the Salish Sea called SalishSeaCast. The model is run daily with high resolution winds and other meteorological forcing, river forcing from over 150 rivers, and temperature, salinity and sea surface at the open boundaries. The physical model is coupled to SMELT (Salishsea Ecosystem Model of Lower Trophic dynamics). The biological model reproduces the expected seasonal cycles in growth, the vertical distribution of phytoplankton, the large spatial gradients between the Strait of Georgia and Juan de Fuca Strait.
A previous, one-dimensional model for the southern Strait of Georgia has been used to accurately forecast the spring bloom, and determine the interannual variability in phytoplankton and carbon cycles in the Strait. Under this project they propose to investigate the physical factors (wind, freshwater flux, clouds, mixing regions, turbid regions) leading to spatial and temporal variations in primary and secondary productivity. This understanding will then allow us to suggest how the productivity of the Strait has changed and how it may change in the future.
The Key Research Questions are:
- What processes control primary and secondary productivity in the Salish Sea and how do they, and thus productivity, vary spatially, seasonally and interannually? and
- Given what they know about past conditions in the Sea and what is forecast for the future, what do these results imply about past and future primary and secondary productivity.
The model results fields will be provided on the web for other scientists to use.
A lower trophic level biological model has been coupled to a three-dimensional physical model of the Salish Sea. The skill of the model in reproducing observed nutrient distributions has been assessed based on comparison with Pacific Salmon Foundation Citizen Science Data. Additionally, a turbidity-based light attenuation parameterization is being developed to improve the model’s ability to reflect phytoplankton dynamics in the plume-influenced southern Strait of Georgia.
The trophic structure of the Salish Sea plankton food web: defining functional groups, energy pathways, and a mechanistic interface between bio-chemical and fish centric ecosystem models.
Team: Brian Hunt (IOF, Hakai Institute), David Costalago (IOF-UBC), Ian Perry (DFO), Karyn Suchy (UVic), Ian Forster (DFO), Evgeny Pakhomov (IOF), Jennifer Boldt (DFO), Villy Christensen (IOF), Chrys Neville (DFO)
Zooplankton are the interface between basal food web processes (physics-chemistry-phytoplankton) and salmon, either through direct consumption or indirectly through forage fish (e.g., herring) pathways. Filling an essential data gap, the proposed project aims to establish a mechanistic understanding of the phytoplankton-zooplankton relationship in the Salish Sea, focusing specifically on trophic pathways among these lower trophic levels.
Physical-chemical conditions drive phytoplankton bloom timing, taxonomic composition, size structure, and quality as food items. How the zooplankton respond to changes in these phytoplankton parameters is determined by their functional trophic group and the resulting trophic pathways, e.g., the contributions of the microbial vs. classical food chains (large diatoms -> copepods -> fish). An understanding of these trophic pathways is essential to a mechanistic understanding of zooplankton response to changing ocean conditions, and the processes that drive salmon early marine survival. The proposed project will explicitly build on and complement Dr. Karyn Suchy’s SSMSP research project “Synchronicity between phytoplankton and zooplankton phenology”, aimed at identifying the seasonal patterns and interannual variability in phytoplankton and zooplankton abundance, biomass and composition in the Salish Sea. The addition of knowledge of trophic pathways will inform how changing zooplankton community structure impacts energy transfer to salmon and other fish species.
Trophic linkages between phytoplankton groups and zooplankton species / groups will be determined using a three-part biochemical approach:
- Fatty acid analysis to measure the contribution of phytoplankton group specific pathways to the zooplankton food web, and the energy content and food quality of zooplankton prey species;
- Stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of bulk tissues bulk tissues to identify zooplankton trophic level, trophic niche space, and assign trophic functional groups that define food-web linkages.
- δ13C analysis of amino acids to measure food web pathways
A comprehensive analysis of the plankton food web in the Salish Sea has never been conducted before. This proposed project is combining food-web size spectra with a suite of biochemical methods (fatty / amino acids; stable isotopes) to identify plankton food-web pathways to juvenile salmon in the Salish Sea, their variability spatially and temporally, their role in the transfer of essential nutrients and energy to juvenile salmon, and implications for juvenile salmon health. The plankton food-web framework developed by this project for the Salish Sea will improve understanding of how environmental conditions impact this ecosystem and its capacity to support juvenile salmon. Additionally, by providing an interface between physical-chemical and food-web modelling efforts this project will contribute to improve stock return forecasting.
A suitable PDF was identified and began in fall of 2017. Funding is for 2 years of study.