Measurement of Aquaculture Chemotherapeutants in Flocculent Matter Collected at a Hard-Bottom Dominated Finfish Site on the South Coast of Newfoundland (Canada) After 2 Years of Fallow

Abstract

The expansion of aquaculture is resulting in sites being installed over a diversity of substrate types, leading to different potential chemotherapeutant degradation scenarios. There is little to no information on the biodegradation and/or persistence of chemotherapeutants at hard-bottom dominated aquaculture sites having little natural sediment. In this study, we measured organic matter (OM) content and concentrations of chemicals linked to finfish aquaculture activities (trace elements, antibiotics and parasiticides) in flocculent matter samples collected close to cages at a site fallowed for 2 years and at an active site, the latter being indicative of flocculent chemical signature during production. Our results show persistence of flocculent matter after 2 years of fallow. The chemical signature of the samples confirms that Cu, Zn, Ca, and P, present around fish cages, are direct markers of aquaculture wastes. Persistence of two pyrethroids, one avermectin, and one antibiotic in grab samples show a potentially lasting association between these chemicals and the OM from fish feed and wastes, even after 2 years. Overall, the concentrations measured do not indicate a direct lethal toxicity on marine organisms (as per studies described in literature) except for Zn. Nevertheless, the long-term persistence of a flocculent mixture rich in chemicals and the lack of information on sublethal and synergistic effects on hard-bottom communities calls for caution and additional studies.

Distribution and geochemical speciation of metals in the sediments of marine aquaculture areas in Japan

“…Similarly, for aquaculture sites in southwestern New Brunswick, Canada, and the San Pedro River, Spain, Cu, Cd, Zn, and Pb were also considered aquaculture markers and were signi cantly linked to OM in the sediments (Mendiguchía et al, 2006;Chou et al, 2002). Cu, Zn, and P were aligned with organic enrichment indicators in the Maritimes and British Columbia aquaculture environments of Canada (Sutherland et al, 2007;Sutherland, 2011), and Zn and Cd tended to correlate with OM in the sediments of the South Coast of NL, Canada (Hamoutene et al, 2018). In sediment from a core adjacent to a marine n sh farm in Lime Kiln Bay, Canada, the increase in Cd was also found to be a result of not only authigenic enrichment but also the high ux of organic materials discharged from sh farm wastes (Smith et al, 2005).…”

“…For British Columbia, Maritimes, and Newfoundland and Labrador region, Canada, 95 (17.8%), 104 (19.5%), 23 (4.3%), and 25 (4.7%) of all sampled stations (n = 533) from sh cage (0-500 m) were enriched with respect to Cu (31.5-241 mg kg-dry − 1 ) and Zn (93.7-670 mg kg-dry − 1 )(Hamoutene et al, 2021). Exceeding levels of Cu and Zn were also presented around sh cages and were assumed to be the direct causes of aquaculture wastes of occulent matter in the South Coast of Newfoundland (27.4-66.0 mg kg-dry − 1 for Cu and 58-726 mg kg-dry − 1 for Zn) and several salmon farms of southwestern New Brunswick (9.1-26.7 mg kg-dry − 1 for Cu and 48.8-102.6 mg kg-dry − 1 for Zn), Canada(Hamoutene et al, 2018;Yeats et al, 2005); Stations enriched in Zn and Cu have been found close to 200 mg kg − 1 (> 250 mg kg − 1 for Zn and > 70 mg kg − 1 for Cu) in Lime Kiln Bay, New Brunswick, Canada(Smith et al, 2005). For the farms on Stewart Island and New Zealand, high levels of Cu ranging from 48 to 150 mg kg − 1 for Cu and 410 mg kg − 1 of Zn were also reported at sampling sites near marine farms(Brooks & Mahnken, 2003).…”

Fish farm effluents cause metabolic depression, reducing energy stores and growth in the reef-forming coral Lophelia pertusa

“…Copper originating from salmon feed or the antifoulants of the net cages may accumulate in soft sediments and in flocculent matter settled on hard bottom underneath and near fish farms (Hamoutene et al 2018, Grefsrud et al 2021) and consequently impact marine fauna. Copper is essential for all organisms in very small levels (therefore added to the feed) but becomes toxic at higher concentrations.…”