Simple rules can guide whether land- or ocean-based conservation will best benefit marine ecosystems

Area of Science:

• Marine ecology
• Conservation science
• Ecosystem management

Background:

• Coastal ecosystems face threats from both land- and ocean-based stressors.
• Efficient management requires comparing the costs and benefits of conservation actions in both realms.
• Understanding the link between terrestrial runoff and marine health is crucial.

Purpose of the Study:

• To quantify the relationship between terrestrial sediment runoff and coastal marine ecosystems.
• To compare the cost-effectiveness of four conservation actions: land/ocean protection and restoration.
• To identify optimal strategies for maximizing light-dependent marine habitats over decadal timescales.

Main Methods:

• Development and application of a dynamic land- and sea-scape model.
• Case study analysis of a seagrass meadow in Australia.
• Evaluation of four conservation strategies under varying ecological conditions.

Main Results:

• Marine restoration emerged as the most cost-effective action in the Australian case study over decadal timescales.
• Identified four key rules of thumb to guide conservation investments based on ecosystem decline and expansion rates.
• Demonstrated that optimal strategies vary significantly with social-ecological context.

Conclusions:

• Marine restoration is often optimal when marine ecosystem decline and expansion rates are similarly low.
• Marine protection is favored when marine ecosystems decline rapidly or catchments are intact with low vegetation decline.
• Land-based actions, particularly terrestrial restoration, are most effective when marine ecosystem recovery outpaces decline significantly.