Novel observations of benthic enrichment in contrasting flow regimes with implications for marine farm monitoring and management

• Published in: Marine pollution bulletin Vol. 66; no. 1-2; pp. 105 - 116
• Main Authors: Keeley, Nigel B., Forrest, Barrie M., Macleod, Catriona K.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15-01-2013; Elsevier
• Subjects: aerobic conditions; Animal and plant ecology; Animal aquaculture; Animal productions; Animal, plant and microbial ecology; Animals; Applied ecology; Aquaculture; Aquaculture - methods; Biological and medical sciences; biomass; Ecotoxicology, biological effects of pollution; Environmental impact; Environmental Monitoring - methods; fish farms; food availability; Fundamental and applied biological sciences. Psychology; General aspects; Geologic Sediments - chemistry; Macrofauna; Marine; Marine and brackish environment; Models, Chemical; monitoring; organic matter; organic wastes; Pearson–Rosenberg model; Salmon; Salmonidae; Sea water ecosystems; Seawater; sediments; site; Spatial Analysis; species diversity; Sulfide; Synecology; Water Movements; Water Pollutants, Chemical - analysis; water pollution; Water Pollution, Chemical - statistics & numerical data; Sulfide; Salmon; Macrofauna; Environmental impact; Pearson–Rosenberg model; Aquaculture; Salmonidae; Fauna; Pearson-Rosenberg model; Marine environment; Sulfides; Vertebrata; Flow regime; Pisces; Environment impact; Models; Benthic zone
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2012.10.024

► Reveals a-typical environmental responses along spatial gradients, due to flow. ► Very high abundances and biomass were evident when organic accumulation was not. ► Moderate-to-high species richness maintained under highly enriched conditions. ► Greater resilience to organic waste streams attributed to biological processes. ► Ramifications for fish farm siting and production and for environmental management.
We examine macrofaunal and physico-chemical responses to organic enrichment beneath salmon farms in contrasting flow environments, and reveal pronounced flow-related differences in the magnitude and spatial extent of effects. Total macrofaunal abundances at high flow sites were nearly an order of magnitude greater than at comparable low flow sites, representing a significant benthic biomass. These very high abundances occurred in conjunction with moderate-to-high species richness, and were evident in the absence of appreciable organic matter accumulation. Biological responses to increasing sulfide were variable; however a significant biological threshold was evident at 1500μM. Macrofaunal responses at high flow sites differed substantially from the Pearson–Rosenberg model. The atypical ecological conditions were attributed to (i) limited accumulation of fine sediments, (ii) maintenance of aerobic conditions in near-surface sediments, and (iii) an abundant food supply. Thus, enhanced resilience to organic waste at well-flushed sites appears related to both biological and physical processes.