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Impacts to the invertebrate community structure of aquatic systems in Nunavut: Stream benthos project
Andrew S. Medeiros, Department of Biology, York University, 4700 Keele St., Toronto, ON, M3J 1P3; firstname.lastname@example.org
Climate change is expected to have wide-ranging impacts on the ecology of aquatic systems in the Canadian Arctic. However, there is a poor understanding of the realized impacts of climate change on the community structure and food webs of these systems. Accurately detecting, measuring, and projecting impairment in arctic aquatic systems is complicated by the fundamental lack of knowledge of the baseline conditions of “undisturbed” arctic aquatic systems. As there are no measures of what a “pristine” habitat is, a reference condition approach is necessary to determine the baseline conditions of the benthic invertebrate communities of undisturbed streams. Without this proper understanding of the baseline biodiversity of invertebrate communities within these systems, it would be difficult to accurately determine the current biological status (or health). Since there is a strong demand for research on how various disturbances (including climate change) may impact arctic aquatic ecosystems, investigations into the current composition and function of these systems is necessary. It is also equally important to have this understanding of the current biota in order to develop proper, biologically sound biomonitoring programs to evaluate impacts resulting from anthropogenic activities. Previous baseline studies conducted by industry-led environmental impact assessments to characterize arctic freshwater ecosystems prior to development rarely include rigorous benthos sampling programs. Consequently, our ability to detect impairment at lower trophic levels in arctic aquatic systems is limited.
Benthic monitoring programs are commonly used to assess the health of streams and rivers in temperate systems, but the low diversity and unique physical habitat conditions of arctic tundra streams prevents the effective use of these sampling protocols and assessment measures. However, Bailey et al. (1998) were able to successfully distinguish disturbed streams (due to mining contamination) from pristine environments in the Yukon with the creation of predictive model based upon a Reference Condition Approach (RCA) (Bowman and Somers 2005). While this approach has the potential to outline major disturbances to benthic communities, less extreme disturbances (e.g. climate warming) are expected to be much more difficult to quantify under current protocols. It is therefore necessary to create an index based upon a meaningful measure of diversity, such as the ecological characteristics of the dominant families specifically found within the undisturbed habitat of the tundra streams characteristic of Nunavut.
Our approach involves focusing on the Chironomidae (Insecta: Diptera) in order to quantify disturbances to streams in Nunavut. Within this family, there are wide differences in the ecological preferences and environmental constraints between genera. Thus, the identification of specimens to the genus (and possibly species) level of organization is necessary as a rapid bioassessment protocol that is sensitive to biological impairment. The focus on the genus-level diversity of the Chironomidae will allow for the identification of changes in abundance as well as compositional changes to their communities in response to ecological disturbances. Therefore, a biogeographic approach across Nunavut is being undertaken to examine multiple streams within multiple regions of Nunavut. While an RCA for each region will require a large sampling commitment for the initial assessment phase, it will facilitate the selection of ecologically significant parameters to use in an index using the predictive model developed from the reference conditions of “pristine” tundra streams. Thus, comparing “pristine” and “disturbed” benthic invertebrate communities in Nunavut streams will require a model and indices to distinguish the threshold values for qualitative labels of health.
In 2005 the Nunavut Research Institute (NRI) initiated a pilot study of the benthos of Peterhead Inlet, part of a river system west of Iqaluit. The Peterhead Inlet study, while useful in terms of a background study, did not allow for a full quantification of the biodiversity present due to the nature of the original protocols used. This background study also outlined several significant methodological problems associated with biomonitoring of arctic tundra systems. Therefore, our research program aims to address these problems by developing sampling protocols more appropriate for arctic stream systems and developing user-friendly reference materials and instructional guides for a community based Benthic Biomonitoring program for Nunavut streams and rivers.
York University and NRI are collaborating to develop protocols for a biomonitoring program as well as attempting to quantify current biodiversity within these systems. From June-September 2007 Andrew Medeiros (PhD. Candidate, York University), Jamal Shirley (Manager of Research Policy and Design), and Andrew Dunford (Manager of Scientific Services) initiated the first phase of this program to establish a baseline reference collection for the Iqaluit area. The benthic invertebrate community composition was sampled for Airport Creek and the Apex River in Iqaluit during this time. Samples were taken from multiple points along each system at multiple times throughout the ice-free period. These systems are of key importance as Airport Creek has long been disturbed due to industrial contamination and sediment input along various points of the stream.
Although the reference samples collected during 2007 provide the first representation of current biodiversity within these environments, a much more detailed sampling regime will be necessary to fully quantify the current reference condition of these systems. However, among the samples collected in 2007 we can already see evidence that there are wide differences in richness and diversity as the season progresses from the initial ice-free period (early June) to the drier re-freeze period (mid-September). Complicating multi-year monitoring is the increasingly large variation in the onset of the ice-free period. Anecdotal evidence suggests that during 2006 the melt and breakup of ice occurred much earlier than in 2007. This variation in the ice-free season also corresponds with the timing and duration of high flow periods as well as the emergence times for the various biota. Future biomonitoring programs will require an understanding of the seasonal dynamics of the benthic community in order to compare changes across multiple years
We were able to adapt existing Ontario Benthic Biomonitoring Network collection protocols (Jones et al. 2005) for these systems by adjusting collection methods to better suit the environmental characteristics of tundra systems. Multiple adjustments to the protocols were made with each collection, and geared towards allowing for future community based sampling in these harsh environments. For example; depending on the time of year, it is difficult to obtain a minimum statistical representation of organisms per D-net sample. Sampling times are therefore greater per kick and sweep than recommended in current protocols. The use of a Marchant box is also not recommended due to the relatively high amount of particulate matter, and the lower relative abundance and diversity of organisms sampled in the study (which is also variable dependant on the time of year). Adjustments such as these are on-going and also depend on the localized environmental conditions of each reach. One drawback to this approach is the increased time necessary to key specimens to genus or species. This may require more training than would be necessary for southern temperate systems, but is necessary.
While we were able to make minor adjustments to currently available protocols, the development of a new set of protocols suitable for biomonitoring programs will take several more years to fully develop. In order to understand how the biota of these systems change throughout the multiple different spatial and temporal scales of arctic tundra systems, emphasis will need to be placed on comparing the biodiversity of multiple points along the reach of multiple streams and rivers throughout Nunavut. These protocols will be further developed, tested, and made available to various community groups and agencies (e.g. Parks Canada, Nunavut Arctic College) for further biomonitoring of arctic aquatic habitats upon the completion of this research program. The continued biomonitoring of these streams, as well as others across Nunavut will allow for a continuous assessment of the health of multiple stream systems across the territory.
While climate change is an important issue for arctic systems, monitoring the current health of streams and subsequent traditional food and water sources they sustain is viewed as critically important, if not more important, to local communities across Nunavut. It is our hope that this program will allow for local community groups to assess the health of their streams and rivers. This would allow for the continued monitoring of biological impairment not only for localized industrial source pollution, but also keep track of upstream climate impacts to the benthic invertebrate communities.
Bailey, R.C., M.G. Kennedy, M.Z. Dervishand, and R.M. Taylor. 1998. Biological assessment of freshwater ecosystems using a reference condition approach: comparing predicted and actual benthic invertebrate communities in Yukon streams. Freshwater Biology 39: 765-774.
Bowman, M. and K. Somers. 2005. Considerations when using the reference condition approach for bioassessment of freshwater ecosystems. Water Quality Research Journal of Canada. 40(3): 347-360.
Jones, C., K. Somers, R. Reid, R. Fletcher, J. Wint ers, T. Reynoldson, and B. Craig. 2005. Ontario Benthic Biomonitoring Network Protocol Manual. Ontario Ministry of Environment and Environment Canada, Dorset, Ontario.
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