Analysis of Nutrient Levels in Canadian Coastal Waters
and
A Case Study on the Influence of Agricultural Activity on
Nutrient Concentrations in Prince Edward Island
SUMMARY
The National Marine Nutrient Database recently developed by Environment Canada was analyzed with the objective of elucidating regional trends in the extent of nutrient over-enrichment in Canadian nearshore coastal waters, and to provide an indication of the nutrient levels that may be used to establish initial regional guidelines and/or reference conditions for dealing with coastal systems exhibiting symptoms of nutrient over-enrichment. In addition, an analysis to determine if any relationship exists between nutrient over-enrichment and the level of agricultural activity that occurs within coastal watersheds was carried out.
The analyses consisted of mapping the levels of four parameters typically used to assess nutrient over-enrichment (nitrogen, phosphorus, chlorophyll a and dissolved oxygen concentration), and basic statistical analyses to determine the degree of regional differences between these parameters. The relationship between agricultural activity and nutrient over-enrichment was carried using information obtained for Prince Edward Island which has a high level of agricultural land use and has been experiencing coastal eutrophication problems for the last several decades.
Results of the regional analyses suggest that West coast nearshore waters have higher nutrient concentrations than East coast nearshore waters. However, this must be considered to be a tentative conclusion as further data screening and validation of the database is required in addition to incorporation of missing datasets.
The analysis of the relationship between nutrient over-enrichment parameters and agricultural activity showed positive relationships between the two for phosphorus, chlorophyll a and dissolved oxygen levels, but no clear relationship to nitrogen levels.
The results of this study provide a general overview of nutrient levels in Canadian nearshore marine waters and represent an important first step toward the development of specific nutrient guidelines to prevent or reduce the impacts of nutrient over-enrichment in our coastal systems.