Mitigating Impacts of Natural Hazards on Fishery Ecosystems

Poster Abstract: Monitoring the Recovery of Organic Enriched Sediments following Targeted Mitigation and Intervention in a Temperate Estuary in the Southern Gulf of St. Lawrence, Canada

François Plante

doi: https://doi.org/10.47886/9781934874011.ch23

Poster Abstract.—The Lamèque estuary, a shallow temperate estuary located in northeastern New-Brunswick (Canada) has experienced algal blooms and ensuing habitat degradation since the late 1990s as a result of anthropogenic nutrient loading. Eutrophication of portions of the bay has resulted in anoxia and H2S production with ensuing human health and fish habitat concerns. Effluents from the local seafood processing plant have been identified as a major source of water and sediment enrichment in the bay.

Growing public protests and increasing air quality degradation led government agencies to undertake a targeted campaign to curb the source and effects of this eutrophication. The seafood processing plant underwent significant water reduction and an effluent treatment retrofit, which has resulted in savings of 2,000 L of water per minute and the removal of 11,000 kg of solid waste per day. Meanwhile, the municipality of Lamèque undertook the task of physically removing decaying plant material along the affected shoreline. This study presents the results of a monitoring campaign that has measured sediment quality since the onset of that remediation project.

Measurements of total sulfides and of oxidation-reduction potentials (Eh) in porewater have been used to determine sediment quality between 2001 and 2006. Our preliminary results show a consistent reduction in levels of sulfides from 2001 to 2006. Estuary waters were severely anoxic in 2001 and 2002, but oxygen levels returned to normal by 2005. Since then, only stations within 10 m of the fish plant processing outfall indicate anoxic conditions and high sulfide concentrations. While there are positive signs that the remediation campaign has had positive impact on Lameque Bay, it is too early to tell if this represents a permanent trend toward normal conditions.