Ecological comparisons of salt marshes and mudflats in contrasting tidal regimes

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This grant will support our study of the ecology of salt marshes and mudflats in Maritime Canada. These ecosystems are dynamic and biologically-productive, valued for providing several ecosystem services (such as storing carbon, filtering pollution, creating nursery habitat for a diversity of organisms, and sheltering coasts from storm activity and sea level rise). Salt marshes are characterized by tough, salt-tolerant grasses able to grow on sediments regularly covered by tidal water. Mudflats are typically found on the seaward side of salt marshes; in the Bay of Fundy, in particular, the mudflats can be vast in extent, extending for several kilometres along the coast and being over a kilometre wide at low tide. These mudflats support an extraordinary abundance of invertebrates, and every summer they become essential feeding grounds for millions of migrating shorebirds. Our research program is dedicated to understanding the structure and inner-workings of salt marsh and mudflat ecosystems. As a long-term research strategy, our approach is to undertake a series of carefully-planned studies, with each study designed to address a specific question that will enlighten our overall understanding. With this grant support, we will undertake specific studies focused on the community ecology of mudflats, on the trophic ecology of salt marshes, and on the ecological connections that exist between the two neighbouring ecosystems. Connectivity among populations, communities and ecosystems can affect population persistence and species coexistence, and may lead to dynamics at regional scales that are not predicted by dynamics at local scales. A general feature of our studies is that we characterize the population and community dynamics of animal and plant species living in two regions that experience very different tidal environments. The Northumberland Strait encounters only small tides, with clear water and strong seasonal changes in water temperature, while the Bay of Fundy is subject to huge tides, with turbid water and much smaller variation in water temperature year-round. The comparison of such distinctive sites in geographically close locations is a powerful research strategy for identifying ecological mechanisms and interpreting observed patterns. Studying the different tidal environments will also improve our understanding of how soft-sediment shorelines may be affected by changes in sea level or tidal amplitudes. Since the proposed studies will be conducted throughout the year, we will also assess the extent and effect of winter disturbance on ecological patterns and processes. Winter effects can be substantial, but have received limited study along coastlines at north temperate latitudes.