Thorleifur Agustsson, Alessio Gomiero, Halldór Pálmar Halldórsson c, Eva Dögg Jóhannesdottir, Thorleifur Eiriksson 2026. Recovery dynamics and ecological resilience: A 20-Year analysis of benthic ecosystem response to production cycles in cold-water aquaculture. International Biodeterioration & Biodegradation 214 (2026) 106394.

Sustainable aquaculture management depends on evidence-based fallowing regimes, yet optimal recovery periods
for high-latitude marine environments remain inadequately defined. We present a longitudinal analysis of
benthic ecosystem dynamics (2002–2022) in Icelandic salmon farming areas, combining long-term monitoring
with an intensive 18-month reciprocal field experiment. Two contrasting sites underwent opposite production
transitions: Glimeyri (peak production to fallowing) and Hamraborg (fallowing to peak production), creating a
paired experiment controlling for seasonal and environmental variability. Sampling comprised macrofaunal
community analysis (n = 280), biogeochemical measurements (ORP, pH, sulphides) and organic enrichment
parameters (C, N, P) across seven events. Results demonstrated predictable recovery trajectories across multiple
production cycles (p < 0.001). Analysis of community development revealed three distinct recovery phases: (1)
opportunistic dominance (0–4 months, Shannon H’ = 1.2–1.8); (2) transitional community (4–12 months,
H’ = 1.8–2.5); and (3) reference-approaching community (advanced recovery stage) (12–18 months,
H’ = 2.5–3.5). A highly significant logarithmic relationship was documented between recovery time and
Shannon diversity (r2 = 0.87, p < 0.0001), with recovery rates averaging 0.12–0.15 H′ units/month during the
initial phase but declining to 0.05–0.08 units/month in later stages. Companion papers address horizontal spatial
distribution and vertical sediment profiles. These findings provide the first robust recovery models empirically
derived for high-latitude aquaculture management.