Water chemistry and physical gradients across the coastal band of eastern Georgian Bay: A coherent habitat template

Abstract

The 125 km long archipelago of islands, reefs and embayments composing the coastline of eastern Georgian Bay connects the adjacent watersheds of the Canadian Shield with the calcareous basin of Lake Huron resulting in gradients of nutrients, major ions, alkalinity-pH, DOC and water transparency. An investigation of the broad distribution of these gradients, extending over four regions of coastline and the 60 km of shoreline from 2014 to 2016 indicated that this onshore-offshore transition in water quality is a predictable feature of the nearshore stemming from the underlying geological transition from land to lake. Consolidating the onshore to offshore gradient is the quasi-channelized nature of mixing across the highly dissected coastal band that adds to the persistence of mixing areas. In addition to water quality, the coastal gradient also encompasses a broad range of physical attributes of the aquatic environment including the thermal, optical, exposure regimes and the physical character of lakebed substrate. Consequently, we hypothesize that diverse forms of aquatic life can be anticipated to select and preferentially distribute across the habitat template embodied by the gradients that span the coastal band of eastern Georgian Bay.