Benoit A. Lalonde

Trace Metal Concentrations in Sediments and Fish in the Vicinity of Ash Lagoon Discharges from Coal-Combustion Plants in New Brunswick and Nova Scotia, Canada

Metals that originate from coal-combustion residue (ash) deposited in water-filled lagoons are eventually released into the environment. This study measured metal concentrations in sediment and fish obtained in the vicinity of two coal-combustion ash-lagoon outfalls on the East River (Nova Scotia) and Grand Lake (New Brunswick), Canada. Of the 34 metals analysed, this study demonstrated that sediment in the immediate vicinity of the ash lagoon discharge in New Brunswick had statistically significant greater concentrations of thallium, arsenic, and antimony than did the sediment obtained from background areas. Tissue arsenic concentrations were increased in fish obtained near the lagoon discharge in New Brunswick but not statistically greater than that of fish obtained from background areas. Neither sediment nor fish obtained near the ash-lagoon discharge in Nova Scotia had significantly greater concentrations of any of the metals measured.

Analysis of Benthic Invertebrate Communities as a Function of Distance from Two Fish-Processing Plant Effluent Discharges in New Brunswick, Canada

Benthic invertebrate communities have been known to change due to impacts from nutrient-rich industrial outputs, such as those from pulp and paper, sewage-treatment plants, or aquaculture. Fish-processing plants have been recognized as contributors of large volumes of nutrient rich effluent to marine and estuarine environments, but their effect on benthic invertebrate communities is unknown. Benthic invertebrates and sediment samples were obtained from marine sampling stations at 0-, 10-, 30-, and 100-m distances from two fish-processing outfalls in Atlantic Canada. Sediment grain size, total organic carbon (TOC), ammonia, sulphide, and redox, as well as invertebrate abundance, density, taxa richness, Simpson’s Inverse Diversity Index, Bray-Curtis Index of (%) Similarity, and the AZTI marine biotic index (AMBI), were determined for all sampling sites. Results from this study illustrate that taxa richness and density significantly increased as distance from the outfall discharge increased. In our study, TOC was only significantly correlated to AMBI but not to the other benthic invertebrate assemblage descriptors calculated in this study (invertebrate density, taxa richness, Simpson’s Inverse Diversity Index). The study results suggest that taxa richness and density may be affected by effluent from fish-processing plants.

Analysis of benthic invertebrate communities downstream of land-based aquaculture facilities in Nova Scotia, Canada

Abstract Land-based aquaculture facilities are located throughout Nova Scotia. They are generally located beside streams, to which they discharge large quantities of used water, and their discharges are usually only monitored for some nutrient parameters at varying frequencies. However, intermittent water sampling is not sufficient to assess any aquatic ecosystem health impacts resulting from discharges. Monitoring benthic invertebrate populations’ characteristics can be used to assess aquatic ecosystem health, and this study evaluated the benthic invertebrate population characteristics downstream of five land-based aquaculture facilities in Nova Scotia. Total abundance and relative abundance of Chironomidae were elevated, while number of taxa, relative abundance of Ephemeroptera + Plecoptera + Trichoptera (EPT), Pielou’s evenness and diversity were reduced at three out of the five sampling locations. Furthermore, a comparison of populations of benthic invertebrates downstream of the facilities to those predicted by the Canadian Aquatic Biomonitoring Network Atlantic reference condition approach model revealed that population characteristics downstream at two out of the five facilities were noticeably different than those predicted by the model. Those population changes are consistent with other studies where nutrient enrichment was correlated to abundance and diversity.

Toxicity testing of freshwater sediment collected near freshwater aquaculture facilities in the Maritimes, Canada

In the Atlantic region of Canada, there are close to 50 land-based freshwater aquaculture facilities, most of which discharge wastewater to freshwater receiving environments. This study was designed to assess the chemical and toxicological characteristics of sediments in those receiving environments. Thirty sediment samples were collected from 3 locations (upstream, outfall and downstream) at seven freshwater aquaculture facilities. Toxicity tests conducted included amphipod growth, amphipod survival and Microtox™. Sediments were also analysed for ammonia/porewater ammonia, redox and sulphide. Porewater ammonia concentration for the amphipod survival test ranged from 0.01 to 42 mg/L at the conclusion of the 14-day survival test. Ammonia concentration in sediment ranged from 0.3–202 μg/g, sulphide concentration ranged from 0.15 to 17.4 μg/g, yet redox ranged from 32 to 594 mV. Microtox™ IC50 values ranged from 108,00 to >164,000 mg/L, yet amphipod survival ranged from 0 to 100%, depending on sampling locations. Amphipod survival was significantly related (P < 0.05) to porewater ammonia (at time = 0 and 14 days) and Microtox™ IC50 was significantly related (P < 0.05) to ammonia, sulphide and redox levels. These results indicate that discharges from some the land-based aquaculture facilities are impacting sediment dwelling benthic invertebrates at the outfall but that impact largely disappears by 100 m downstream. Furthermore those impacts were rarely detected during the early winter season, when biomass production was at the lowest.