In addition to a loss of the fishery, there could be ...

In addition to a loss of the fishery, there could be possible extinction of the Lake Ontario and upper St. Lawrence River stock,-a species-wide decline, and local and regional ecological impacts of eliminating eels from the freshwater and marine ecosystems.

PALEOENVIRONMENTAL RECORDS OF POSTGLACIAL CLIMATE CHANGE IN THE PRAIRIE ECOZONE Donald S. Lemmen, Terrain Sciences Division, Geological Survey of Canada, Calgary Alwynne B. Beaudoin, Archaeological Survey, Provincial Museum of Alberta, Edmonton Robert E. Vance, Terrain Sciences Division, Geological Survey of Canada, Ottawa The climate system operates at temporal scales ranging from diurnal to multimillennial. Instrumental climate data from the Prairie Ecozone rarely extends more than a century, and therefore is insufficient to detect trends longer than a few decades. Ecological monitoring data for this region tend to extend for even shorter intervals (several decades at best) and often provide information that has high year to year variability, making it difficult to assess whether trends are "noise", reflecting inherent variability within the systems being monitored, or are responding to more fundamental environmental changes. In contrast, recent paleoenvironmental work on the Canadian Prairies and elsewhere has clearly shown a sequence of long-term, broad-scale climatic trends, roughly synchronous over wide areas, and their associated ecological responses. The paleoenvironmental record, therefore, provides the context against which to examine traditional ecological monitoring data. The paleoenvironmental record makes several unique contributions to our understanding of climate change and ecosystem response. These include: i) documenting the full range of postglacial climatic variability; ii) recording ecosystem response to a range of past climate changes; iii) providing analogues for impacts associated with future climatic scenarios, iv) integrating the cumulative effect of impacts over time, and v) reconstructing spatial patterns in major ecosystem components. Much of the knowledge of postglacial environments on the Prairies has been derived from the study of pollen records recovered from lakes and wetlands. There are about 100 paleoenvironmental records available, with more from Alberta than the other prairie provinces. Most records have been obtained from the southern boreal forest, the parkland and the mountains. In recent years, other proxy climate indicators, such as diatoms, ostracodes, plant macrofossils and geochemistry, derived from lake or wetland records, have considerably refined our understanding of past environmental changes.

The oldest well-dated postglacial paleoenvironmental records in the Prairie provinces extend to around 11,000 BP (radiocarbon years before AD 1950). The oldest archaeological sites in the region also date >1 0,000 BP, indicating that humans have been an integral part of the ecosystem for most of the postglacial period. Paleoecologists have only just begun to consider how to detect human impacts prior to Euro-Canadian settlement in their records. Distinguishing anthropogenic from climatic and other environmental signals may be an important concern for paleoecologists in the future. At a very generalized level, paleoenvironmental records for the Prairies concur in showing a broad three-part division of the postglacial. The early part (prior to about 9000 BP), for which there are comparatively few records, shows a sequence of rapid vegetation changes, from tundra-type vegetation, to more shrub-rich vegetation, to a predominantly treed landscape in the parkland and boreal forest. These rapid vegetation changes reflect postglacial migration of plants into the region,

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soil development, and geomorphic adjustment of the landscapes to postglacial conditions, all of which tend to blur the climate signal. Between around 9000 and about 6000 BP, many records show evidence of aridity, increased salinity and higher than present temperatures, with the Prairie grasslands probably extending up to about 80 km further north. This interval (which is time transgressive across the Prairies) is known as the Hypsithermal. After about 6000 BP, increased moisture and probably cooler temperatures are inferred from rising lake levels, decreased salinity, southward advance of the boreal forest margin, and the inception of peat accumulation in central Alberta. This cooler, wetter interval resulted in renewed ice accumulation in the Canadian Rockies which led to the first well-marked Neoglacial advance around 4000 BP. A series of ice advances have occurred in the last 4000 years, although most glaciers show their maximum advances in the last few centuries, during the Little Ice Age. These general climate changes include considerable smaller scale variability. For example, within the last millennium there were two broad climate phases: the Medieval Warm Period, ending around the 12th century, followed by the Little Ice Age. Within each of these intervals, even smaller scale climate changes, on the order of decades or less, have been detected. For instance, during the late 19th century, the era of EuroCanadian exploration and settlement of the grasslands, dendroecological records have shown sequences of drought years , interspersed with wetter intervals. Prior to this decade, few paleoenvironmental records were available within Prairie Ecozone, despite the dramatic demonstration of the vulnerability of the region's ecologic systems to disturbance and climatic change during the "Dirty Thirties". Since 1991 , the Mixed Grassland and Cypress Upland ecoregions have been the focus of the Geological Survey of Canada's Palliser Triangle IRMA (Integrated Research and Monitoring Area), with the objective of using the paleoenvironmental record to better understand the potential impacts of future climate change. Continuous sedimentary records from lakes, some extending to more than 9000 BP, document past periods of significantly increased and decreased aridity, and the response of both biotic and abiotic ecosystem components. The interval between ca. 5000 and 7000 BP serves as a potential analogue for the impacts of climate change under a 2 x C02 scenario, because climate conditions inferred from the paleoenvironmental record suggest that mean annual temperatures were 1-2°C warmer, and growing season precipitation was 15% lower than present, over much of the prairie region. At this time regional water tables lay more than 4 m below present. The few remaining surface water bodies were generally saline to hypersaline, indicating high evaporation rates, and unvegetated surfaces were subject to enhanced wind erosion.

The diet of Arctic Tern chicks predicts herring catches in the Bay of Fundy Krista Arney and Tony Diamond. Atlantic Cooperative Wildlife Ecology Research Network University of New Brunswick, Fredericton, New Brunswick, E3B 6E1 The concept of using seabirds to follow changes in prey stocks has been well documented (Barrett et al., 1987; Cairns, 1987; Furness and Barrett, 1991 ; Montevecchi and Berruti, 1991; Monaghan et al., 1991; Nettleship, 1991 ; Montvecchi, 1993). Seabirds respond to changes in food supply in a variety of ways. These responses can be reflected in adult survivorship, breeding success, or changes in behaviour, such as diet switching, colony attendance, and activity budgets. Seabirds interact with commercial fisheries in several manners. They can harvest the same size or age of

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The Ecological Monitoring and Assessment Network Report on the

Third National Science Meeting January 21-25, 1997 Saskatoon, Saskatchewan

Compiled by Ashok Lumb

Ecological Monitoring Coordinating Office Canada Centre for Inland Waters 867 Lakeshore Road, P.O. Box 5050 Burlington, Ontario, Canada L7R 4A6

July 1997

i

The Ecological Monitoring and Assessment Network Report on the

Third National Science Meeting January 21-25, 1997 Saskatoon, Saskatchewan

Ecological Monitoring Coordinating Office July 1997

1+1 Environment Canada

1+1 Envlronnement Canada