Spatial and temporal dynamics in macrobenthos during recovery from salmon farm induced organic enrichment: When is recovery complete?

• Published in: Marine pollution bulletin Vol. 80; no. 1-2; pp. 250 - 262
• Main Authors: Keeley, Nigel B., Macleod, Catriona K., Hopkins, Grant A., Forrest, Barrie M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15-03-2014; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Animal aquaculture; Animal productions; Animal, plant and microbial ecology; Animals; Applied ecology; Aquaculture; BACI; Benthic ecology; Biological and medical sciences; Conservation, protection and management of environment and wildlife; Ecosystem; Ecotoxicology, biological effects of pollution; Environmental degradation: ecosystems survey and restoration; Environmental Monitoring; Environmental Restoration and Remediation; Fallowing; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; General aspects; Generalities. Agricultural and farming systems. Agricultural development; Geologic Sediments - chemistry; Invertebrates - classification; Invertebrates - growth & development; Marine and brackish environment; Parallelism; Remediation; Salmon; Salmonidae; Spatio-Temporal Analysis; Water Pollutants - analysis; Water Pollution - statistics & numerical data; Benthic ecology; Parallelism; Remediation; BACI; Fallowing; Aquaculture; Salmonidae; Organic matter; Ecology; Agroecosystem; Marine environment; Medium enrichment; Vertebrata; Dynamics; Pisces; Benthos; Ecological recovery; Rehabilitation; Benthic zone
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2013.12.008

•Long-term spatially explicit study of recovery from extreme benthic enrichment.•Substantial recovery in first 2years, largely complete after 5years.•Identified on-going macrobenthic successional instability using novel methods.•Challenges concepts of recovery and highlights need for consensus on definition.•Complex biotic indicators and those which integrate other variables most robust.
This study documents eight years of benthic recovery at a highly impacted salmon farm. Substantial recovery occurred in the first 2years, and was assessed to be complete after ∼5years. However, minor differences were still evident, along with some on-going benthic instability, attributable to medium-scale spatial movements and successional patterns of macrobenthos. Quantifying the endpoint of ‘recovery’ proved challenging due to: lack of a widely accepted definition, inherent variability in recovering sediments, differing trajectories of impact and reference sites, and statistical challenges. More complex biotic indices and metrics incorporating multiple variables were the most robust indicators. Statistical tests for ‘parallelism’ in the trajectories of Cage and Reference sites proved useful, but results were contingent upon how the method was applied, and should therefore be used in conjunction with data-visualisation methods. The study highlights the importance of a predetermined recovery endpoint, and using multiple indicators and a weight-of-evidence assessment approach.