Work

A coupled water-quality–Ecopath with Ecosim model incorporating sand-lance aestivation dynamics in the Harima-Nada Sea

Year: 2026

Type: article

Abstract: Sand lance ( Ammodytes japonicus ) is an important forage fish in the Harima-Nada Sea, Japan, but its stock has declined markedly in recent decades under concurrent changes in nutrient availability and water temperature. To clarify the mechanisms underlying these changes, we developed a region-specific coupled water-quality–Ecopath with Ecosim (EwE) model that explicitly incorporates sand-lance aestivation dynamics. The model integrates temperature-dependent production and consumption, nutrient-dependent primary production, an empirical relationship between nutrient levels and dissolved oxygen, DO-dependent non-predation mortality, and temperature-dependent onset, termination, and mortality during sand-lance aestivation. Model performance was evaluated using PREBAL diagnostics and comparisons with historical biomass, catch, and phytoplankton data. We then conducted single-driver sensitivity analyses for nutrient concentration, water temperature, prey availability, and predator biomass to isolate the mechanistic pathways through which each driver affects sand-lance biomass. The model reproduced major long-term patterns in the Harima-Nada food web and indicated that sand-lance biomass was strongly controlled by bottom-up processes mediated through nutrient availability and Calanus sinicus . Moderate nutrient enrichment enhanced sand-lance biomass by supporting lower-trophic production, whereas excessive enrichment increased hypoxia-related mortality and weakened trophic transfer. Warming reduced sand-lance biomass by prolonging the aestivation period, shortening the productive season, increasing high-temperature mortality during aestivation, and reducing the availability of thermally sensitive prey. Under the present scenario design, prey-availability scenarios produced larger biomass responses than predator-biomass scenarios, indicating a particularly strong bottom-up pathway in the model. These results demonstrate that incorporating species-specific aestivation dynamics into EwE provides a mechanistic basis for evaluating sand-lance responses to environmental change and for developing future multi-driver applications in coastal ecosystem management.

Source: Ecological Modelling

DOI: 10.1016/j.ecolmodel.2026.111861

Authors: Shogo Minamiyama, Akio Sohma

Institution: Osaka City University

Language: English

Topic: Marine and fisheries research

Subfield: Global and Planetary Change

Field: Environmental Science

Domain: Physical Sciences

SDGs: Life below water, Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $2,810