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Understanding whole-system dynamics
Marine ecosystems connect biological communities with physical and chemical environments across multiple spatial and temporal scales. Models represent species groups, energy flows, and environmental drivers so researchers can examine feedback, emergent behaviour, and interactions beyond a single-species approach.
Drivers of marine ecosystem change
Climate change and fishing pressure can alter marine systems individually and through their combined effects.
Climate change
Ocean warming affects species through their thermal tolerances, influencing metabolism, growth, reproduction, and survival. Distribution, community composition, trophic structure, and productivity can change as temperatures shift. Responses are heterogeneous: temperature-tolerant species may increase biomass in some shallow systems, while deep-sea and cold-adapted systems tend to be more vulnerable.
Fishing pressure
Fishing acts directly through the removal of target species, bycatch, and seabed disturbance. It also acts indirectly by altering food webs and predator–prey dynamics. Removing key species can produce non-linear and system-wide effects, particularly under changing environmental conditions.
Combined pressures
Climate change and fishing can amplify ecosystem instability, reduce resilience to environmental variability, and accelerate declines in vulnerable systems. The Ecosystem Approach to Fisheries Management (EAFM) accounts for multi-species interactions, environmental variability, and cumulative and cross-sectoral impacts.
Climate and fishing interactions
Climate impacts can propagate through ecosystems through trophic cascades. Research focuses on the combined effects of climate change and fishing and their influence on:
- biodiversity and trophic structure;
- stock productivity and recruitment dynamics; and
- ecosystem resilience and stability.
These interactions are particularly relevant in Irish shelf and slope systems. These systems support high biodiversity across life stages and have experienced historical overexploitation. Fishing pressure is decreasing, but the systems remain vulnerable.
Multi-model approaches and validation
The Marine Institute develops and applies integrated ecosystem modelling frameworks to understand marine ecosystem change in Irish waters and the Celtic Sea. Using several approaches strengthens confidence in projections and helps researchers explore structural uncertainty and model sensitivity.
Ecopath with Ecosim
We are building on existing Ecopath with Ecosim (EwE) models of the Celtic Sea to represent ecosystem structure and changes through time.
Mizer models
We are developing mizer models for size-spectrum analysis, allowing researchers to examine ecological patterns through organism size and trophic interactions.
Model comparison and validation
We compare model outputs and validate them against historical survey and fisheries data to test model sensitivity and assess the reliability of projections.
Developing the Celtic Seas Atlantis model
Atlantis represents trophic pathways from primary producers to top predators. It also incorporates fishing pressure and management scenarios.
Development of the model involves:
- parameterising biological processes across trophic levels;
- developing functional group structures;
- quantifying energy and biomass fluxes;
- testing sensitivity and validating the model against observational data; and
- integrating the platform with downscaled regional oceanographic models.
This approach supports the representation of ecosystem-scale dynamics under climate forcing and anthropogenic pressure.
Supporting ecosystem-based management
- simulate future scenarios under different climate and management pathways
- assess trade-offs between conservation and fisheries yield
- inform sustainable exploitation strategies