Reefs provide important spawning habitat for lithophilic fish, but sediment accumulation within substrate interstices can limit habitat availability and egg incubation success. A nested wave-current-sediment modeling framework is proposed to evaluate reef functionality in large freshwater systems, resolving fine scale processes while retaining basin-scale forcing. We examined the natural Shorehaven Reef (SR) in Lake Erie, a benchmark for hydrodynamic conditions of functioning spawning habitat, and the artificial Olcott Reef (OR) in Lake Ontario to assess whether its structure reproduces similar hydrodynamic and sediment transport patterns. Eastern reef slopes at SR corresponded with elevated shear stress and sediment removal, while removal at OR was more limited, suggesting reef geometry and site forcing constrained flushing. Relative spatial ranking of sediment layer change remained similar across sensitivity scenarios, with Spearman correlations of 0.96. The modeling framework can evaluate alternative reef configurations using modeled hydrodynamic and sediment responses to inform site-specific design and restoration.
Sustainable development of coastal lagoons facing complex socio-ecological crises requires quantification of impacts of solutions on all sectors involved. We present a System Dynamics Model (SDM) representing interactions between agriculture, livestock, tourism, and nutrient stocks (aquifer, soils, wastewaters) of the Mar Menor socio-ecological system (SE-Spain), following a participatory process. We applied the SDM to evaluate 22 individual solutions and 3 adaptation scenarios based on contrasting Shared Socioeconomic Pathways (SSP1, SSP2, SSP5) and stakeholder inputs. Results show that agriculture drives degradation while recycling nutrients from livestock and urban wastewater, and that legacy Nitrogen and Phosphorus in soils and groundwater limits lagoon recovery. Business-as-usual (SSP2) and agricultural intensification (SSP5) scenarios reduce water security due to climate change and groundwater contamination. End-of-pipe interventions do not provide long-term solutions, whereas source-oriented interventions lower nutrient inputs, providing socioeconomic benefits. A sustainability-focused scenario (SSP1) results in moderate economic growth, environmental improvements, and highest Total Economic Value.
Agent-based models (ABMs) are widely used to study socio–environmental systems. By integrating environmental modelling with behavioural theories, they enable to analyse how decision-making processes shape environmental outcomes. To speed up model development and enable cumulative theorising, it has been proposed to modularise components relevant across applications as reusable building blocks (RBBs). This paper describes an example of adopting the idea in practice using AGENTBLOCKS, a new open access platform for publishing RBBs. We present the first coordinated interdisciplinary effort of eleven modelling groups to identify, extract, review, and publish 14 decision-making RBBs from existing ABMs using AGENTBLOCKS. From this compilation, we extracted a decision tree to identify and scope reusable model components. Using a mixed-methods approach combining RBB criteria assessment, thematic coding of editorial feedback, and contributor surveys, we suggest empirically informed practices and next steps to lower the barrier for reusable coding practices in socio–environmental applications.
