The effects of climate change on marine ecosystems in the Arctic have rarely been studied collectively. As part of the 4th International Polar Year, Paul Wassmann gathered together the results of years of studies to investigate the major effects that climate change is having on arctic marine ecosystems and to postulate what studies could be done to further advance our scientific knowledge of the region. The basic processes and features of arctic marine ecosystems that will be affected are the seasonal ice zone (SIZ), advective flow and regulation, the relationship between the blooming of primary producers and their consumption by secondary producers, pelagic-benthic coupling, and diversity and distribution of species. Conceptual and coupled physical-biological ecosystem models were used to determine that primary production will increase in certain areas but will remain stable overall, fisheries production will not increase, and that the stratification of arctic waters may actually decrease Arctic Ocean productiveness in the longer term. Additionally, ice and phytoplankton algae may experience longer blooms which will decrease vertical export of nutrients and change food webs. Although freshwater advection will facilitate the ability of fish to survive arctic winters, as the ecosystem decreases in salinity, plankton and smaller organisms will prosper. (Wassmann 2011) To monitor these effects, further research needs to take place in the Fram Strait, the Siberian shelf, and the Central Arctic Ocean. Studies need to encompass all seasons, and the time series analysis framework is recommended. (Wassmann 2011)—Katherine Recinos
Wassmann, P., 2011. Arctic marine ecosystems in an era of rapid climate change. Progress in Oceanography. 90, 1-17.
Wassmann begins with an overview of where studies have been done in the Arctic Ocean region. Most of the major regions, such as the Barents Sea and the Canadian Arctic Archipelago have data available from between two to eleven studies. However, there is a dearth of knowledge from the Eastern Siberian Sea and accompanying shelf caused in part by the withholding of information by Russia and the general disorganization of studies that have been carried out there. Of the Arctic Ocean studies that research is available from, the abovementioned processes and features are being effect by climate change: seasonal ice zone (SIZ), advective flow and regulation, the relationship between the blooming of primary producers and their consumption by secondary producers, pelagic-benthic coupling, and diversity and distribution of species. Many of these processes are intrinsically linked; regional and time variation studies have determined that the SIZ will be affected by global warming, which will change blooming patterns among primary producers, which will then change nutrient distribution among water strata. This would subsequently affect pelagic-benthic coupling and species biodiversity. Wassmann gives an example from a study involving Calanus glacialis, a copepod. C. glacialis depends on the ice algal and pelagic algal blooms for food, and its life cycle is timed according to traditional seasonal patterns. Pelagic algal bloom is “governed to a larger degree by ice thinning and less predictable ice breakup.” As the timing of the bloom changed, C. glacialis biomass decreased. This effect of autotroph blooming on secondary producers is highly variable and can be seen across a number of species.
Wassmann then describes the effects of advection on the Arctic Ocean. Water is predicted to enter the Arctic Ocean from two main sources: the warmer ocean further south, and freshwater rivers. This has the dual effect of increasing water temperature and decreasing salinity. Marine ecosystem biomes and stratification of water by salinity will change in response. Tests for carbon in sediment and nutrients such as nitrogen in the water show that ecosystem productivity is already being affected in some regions as a result. A warmer Arctic Ocean could also attract species originally native to further south and facilitate the breeding of those that already live there (ex. the Arctic Cod). It also limits the amount that primary production can increase because although there will be an increase in light, there will be an increase in secondary producers.
Climate change effects on arctic marine ecosystems are usually modeled one of two ways, conceptually or numerically. The numerical model described in this paper is a type of coupled physical-biological ecosystem model. It looks at how chemical and oceanographic variables could affect biological processes and species dynamics. Data from a number of studies using these models was collected and summarized by Wassmann. The major trends and expectations extrapolated are those in the introduction paragraph.
Wassmann concludes with a discussion of what further research should be done. The Fram Straight, the central Arctic Ocean, and the Siberian ice shelf are areas where little to no research has been conducted. More data is also needed on Arctic weather, SIZ, and “large-scale regulation of ecosystem function.” (Wassmann 2011) Time series analysis would be beneficial as they allow scientists to see trends over time, but it is often difficult and expensive to do annual studies in one of the world’s harshest environments. Wassmann advocates for the continued application of the physical-biological coupled 3D SINMOD and remote sensing models and the implementation of comparative studies. International cooperation paired with these techniques will help scientists continue to observe the exact effects of climate change on the Arctic Ocean.