Exploring the Impacts of Environmental Stressors on the Beaufort Sea Ecosystem

May 12, 2010 10:08

From the production and distribution of microscopic algae to the health of belugas and the feeding preferences of bowhead whales, Fisheries and Oceans Canada (DFO) scientists have been probing the Beaufort Sea in Canada's Western Arctic to explore the cumulative impacts of environmental stressors on this complex ecosystem. The studies comprise the DFO Beaufort Sea Shelf Ecosystem Research Initiative (ERI), which encompasses an area from the coast out to about 200 metres in depth and includes the proposed Tarium Niryutait Marine Protected Area (MPA), reports www.megafishnet.com with reference to Fisheries and Oceans Canada.

The productivity of this region, particularly the coastal zone, has long been important for the traditional lifestyle of Inuvialuit and Gwich'in people in the area. In the face of various stressors including climate change and oil and gas exploration and development, the ERI team is studying how these factors may impact the Beaufort Sea Shelf and coastal area.
Ecosystem Research Initiative (ERI) mandate

The ERI encompasses several interrelated themes. Researchers are studying marine and anadromous fish, which move between fresh and marine water, as pivotal ecosystem components. They are also assessing the seasonal and spatial distribution of beluga and bowhead whales as well as indices of marine mammal health including diseases, contaminants and the genetic integrity of populations. Integral to the research are studies of the status and dynamics of the lower food web including primary producers, which can respond rapidly to changing environmental conditions. Another key part of the ERI is the assessment and development of approaches to determine the cumulative impacts of stressors on individual components of the ecosystem. This involves integrating the results of each study to develop a comprehensive picture of key ecosystem connections and drivers that can be monitored to evaluate impacts.

"The findings of our research can be used to help manage and protect the integrity of this region, including the Marine Protected Area, not just individual species," says ERI coordinator and Arctic biologist Dr. Andrea Niemi of the DFO Arctic Aquatic Research Division in Winnipeg, Manitoba.
Stressor in the Beaufort Sea

Stressors within the ERI area include harvesting, marine transport with associated noise disturbance and the potential release of invasive species, contaminants from local and global sources (e.g., mercury) and oil and gas exploration and development. Since the stressors do not impact the ecosystem independently, their cumulative effects need to be assessed in order to develop effective management strategies for the ecosystem.

Oil and gas exploration is associated with increases in transportation and seismic surveys as well as potential shoreline development such as road construction. "Much of the oil and gas activity has taken place in near shore regions, but more recently it has increased in offshore areas with active leases," says Dr. Niemi.

"Climate change and variability is another overriding stressor in the Beaufort Sea. Summer sea ice cover has declined by about 11 percent per decade, accompanied by an earlier melt," says Dr. Niemi. "This may lead to a longer open water period which would increase light availability and influence the production of phytoplankton and its transfer to organisms that eat it. Changes in the timing and distribution of primary (phytoplankton) production are key factors that can impact the structure and functioning of the entire ecosystem." The team is also exploring how the ecosystem may be affected by changes in the flow of the Mackenzie River and the nutrients and sediments it carries.
Emerging findings: beluga and bowhead whales

As the team continues to gather information on ecosystem components and linkages, some interesting results are emerging from various studies.

Research on contaminants in beluga and the food they eat has so far revealed that mercury contamination is higher in larger males that feed offshore. Their health may also be affected by stress which could make them more susceptible to disease. The ERI is working towards integrating measurements of marine mammal health (e.g., disease and contaminant levels) and condition (e.g., nutrition and stress) to obtain a more complete understanding of how environmental factors directly or indirectly influence marine mammal health.

Knowledge of the distribution and abundance of bowhead whales is important for protecting these animals in light of the industrial activities in the area. For several weeks from early August to late September or early October, bowhead whales gather in several localized areas of the Canadian Beaufort Sea to feed. The shallow, shelf waters offshore of the Tuktoyaktuk Peninsula were the most attractive feeding area for the bowheads. Research reveals that in 2007 and 2008, more bowhead congregated in this area of the southeastern Beaufort Sea to feed than in 2009 and in the 1980s. Variations in the feeding location of bowheads from year to year are believed to be linked to changes in oceanographic conditions, which influence the concentration of zooplankton that bowheads feed on.

Real-time knowledge of where bowheads gather provides an opportunity to establish mitigation procedures to protect them from open-water seismic surveys carried out in conjunction with hydrocarbon explorations. Seismic surveys have been ongoing between 2006 and 2009.
Marine and anadromous fish research

ERI leveraged research also involves assessments of the distribution, abundance and habitat of anadromous and marine fish. Specific studies examined their diets, genetics and contaminant levels. The work supports databases, modelling and mapping required to address impacts of industrial activity and other stressors in near- and offshore areas.
Lower food web studies

Team members surveyed organisms lower on the food web, which are most likely to be affected by environmental changes first. Data collected include water and sediment chemistry, the distribution and biomass of phytoplankton, zooplankton and benthic (bottom dwelling) invertebrates. Among the findings of this research is that bowheads tend to feed in areas with concentrations of lipid-dense, high calorie centric diatoms and protozoans (algae and microscopic aquatic animals).

Also under study is the timing and amount of phytoplankton production, which is the primary food for zooplankton and other invertebrate grazers. One goal is to determine the effects and causes of mismatches in timing of phytoplankton production and the presence of organisms that feed on phytoplankton. These mismatches can have important effects on ecosystem structure, function, integrity and health.
Ecosystem modelling

The team has initiated the integration of data from the various research projects into computer models of the ecosystem, which would serve as a valuable tool for ecosystem management in the area. Computer modelling helps to organize and integrate data and identify key ecosystem connections. It also highlights key gaps in knowledge that still need to be explored. "For example, we generally know the structure of the ecosystem, but there is a lot more to learn about ecosystem connections, and modelling can help us gain a better understanding of that," says Dr. Niemi.

"Computer simulations will also enable us to project how the Beaufort Sea Shelf might respond to different scenarios of change within the ecosystem," she adds. "For example, if the sea ice continues to disappear earlier and we end up with a two fold increase in phytoplankton production, we can use computer modelling to explore what impact that could have on the rest of the ecosystem including fish and whales. In the future, this ERI will continue to integrate results in order to address complex questions for the management of the Beaufort Sea Shelf."

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