Document Type

Thesis

Degree Name

Master of Environmental Studies (MES)

Department

Geography & Environmental Studies

Faculty/School

Faculty of Arts

First Advisor

Mary-Louise Byrne

Advisor Role

Thesis Supervisor

Abstract

The Green alga genus Caldophora is one of the most abundant kinds of algae worldwide, found in both freshwater and marine environments. It prefers nutrient-rich waters and requires a rocky substrate and water movement for growth. When water temperatures reach 22 to 26 C, the alga dies and washes into shore in large mats. Dead Cladophora produces a terrible odour, reduces property values and can alter the taste of drinking water. At Presqu’ile Provincial Park, maximum Cladophora sloughing occurred July 22 1999, the same time as peak summer park visitation begins. This results in the fouling of the Park’s beaches and campground areas. The result is a loss of revenue as some visitors avoid the Park during the summer months. The deposition of the algae on the beaches has become an issue for two reasons. It now occurs later in the season than in the early 1990s. The primary reason for the increase in Cladophora at Presqu’ile is increased water clarity in Lake Ontario in the nearshore zone. Zebra mussels (Dreissena polymorpha) filter particles out of the water while feeding and light now penetrates deeper, allowing Cladophora access to new areas for growth. There is not an increase in Cladophora biomass per square metre compared to 1982 and 1983, but there is now more suitable habitat on which growth is occurring. The algae is also benefitting from an increase in bird biomass in the offshore colony. Although the total number of nests has decreased, Ring-billed Gulls (Larus delawarensis) have been replaced by the larger Double-crested Cormorant (Phalacrrocorax auritus). The birds ensure that the local Cladophora is not phosphorus limited, but growth may be limited by other nutrients at Presqu’ile.

Convocation Year

2000

Convocation Season

Spring

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