Climate change is driving a global redistribution of marine biodiversity, forcing critical habitat-forming species like seagrasses and brown macroalgae to shift poleward.

Knowledge gap

While range expansions into newly suitable habitats can partially offset the negative impacts of projected range losses, traditional models often rely on oversimplified assumptions of marine connectivity, such as unlimited dispersal. The extent to which ocean currents restrict or facilitate species redistributions remains a critical and largely unquantified gap in our understanding.

Main approach

To quantify this influence, we developed a framework linking species distribution models with biophysical connectivity models. We examined the redistribution of 467 marine forest species under end-of-century climate change scenarios.

Technological challenge - how we tackle the study

We combined high-performance distribution models generated with an ensemble of advanced machine learning techniques with global dispersal pathways simulated using 21 years of daily ocean current data. By assembling connectivity estimates into a global directed graph, we utilized network analysis to map multigenerational stepping-stone colonization pathways across shifting climates.

Main finding

Oceanographic connectivity is a major limiting factor for species shifting their distributions.
Range expansions are reduced by up to 38% in area for seagrasses and 48% for macroalgae when accounting for average dispersal duration.
Well-defined dispersal barriers restrict expansions into highly suitable regions, such as the Okhotsk Sea, New Zealand, and the Arctic.

Main implications

These findings highlight the need for a paradigm shift in marine biodiversity assessments. Integrating knowledge of oceanographic connectivity alongside habitat suitability is essential to design well-connected networks of marine protected areas and promote targeted assisted colonization efforts, aligning with global 2030 biodiversity targets.