The short version
Seagrasses nurse fish, clear the water, protect shorelines and bury carbon, yet a 2026 review by 16 authors argues that warmer, darker and more variable water is changing the rules for keeping them alive. The authors pulled together research from around the world on how climate and local pressures reshape meadows, food webs, fisheries and carbon storage. They found that cleaning up local water is still the foundation, but it may no longer be enough: heatwaves are already killing long-lived seagrasses, and fast-growing, heat-tolerant species are filling the gaps, storing less carbon. They propose three steps: grow and plant seagrass at larger scale, track and forecast shifting stress and species ranges, and manage for species that can handle the conditions ahead.
What the report covers
This is an overview article (a review of existing studies, not new field work) that looks at seagrasses worldwide and at three time scales: now, the next 50 years, and the next century.
- How climate and non-climate pressures drive seagrass gains and losses, including "squeezes" on meadows from the deep edge (murky water), the shallow edge (heat) and the shoreline (hardened shores that block landward migration).
- How species, traits and food webs may shift: opportunistic species taking over now, climate migrants and new grazers and predators over the next 50 years, and new Arctic meadows by 2100.
- How those shifts may change two services, seagrass fisheries and blue carbon (carbon stored in plants and sediments).
- What restoration and management need: restoration at larger scale, genetic and microbial tools, mariculture (growing plants in managed facilities), and assisted migration (moving plants to places that will suit them in future).
- Monitoring, modeling and mapping tools for catching change early, and the governance and policy changes that could support them.
What it found
- Water quality still comes first. Wastewater, farm and land runoff, and sediment have caused extensive seagrass losses by clouding the water and fueling algae. Cutting stormwater runoff, nutrient loads and sediment has consistently let meadows recover, and planting works best when combined with those gains (Hensel et al., 2026).
- But old targets may no longer fit. Marine heatwaves, sea level rise and other climate stresses act separately from water quality and cannot be managed locally. The authors say water quality improvements alone may not benefit the species best able to persist, and that today's conditions already differ from those used to set many water quality and restoration targets.
- Tolerant species move in. When long-lived, slow-growing seagrasses die back from combined stresses such as heat and poor clarity, opportunistic species like Ruppia often expand into the space. In Chesapeake Bay, heat-tolerant Ruppia has taken over after eelgrass die-back. The authors expect more of this over the coming decades.
- Less carbon stored. Many opportunistic species store up to 11 times less carbon in their tissues than larger, persistent species. Seagrass meadows hold an estimated 665 to 1,699 teragrams of organic carbon in the top 30 cm of sediment worldwide, so a shift toward small, short-lived species could reduce how much carbon meadows hold and how stable that storage is.
- Squeezed from several sides. Nearshore waters near the eastern USA and several other regions are warming nearly three times faster than the global average. The authors expect mid-Atlantic US seagrasses to face subtropical temperatures by 2070. Where shorelines are hardened, meadows cannot migrate landward as seas rise.
- New grazers and fewer migrants. Warming and conservation successes are moving large grazers and fish predators poleward, adding grazing pressure and disrupting the small animals that keep algae off the leaves. Low-diversity regions such as the temperate northwest Atlantic have few species available to migrate in.
- Small restorations often fail. Restoration that is small and separate from stressor management has high failure rates. Seed-based planting at large scale, in clear water, can be the most successful and cost-effective approach. Planting fast-growing, tolerant species together with persistent ones improved success under stress (Hensel et al., 2024, cited in the review).
- Three proposed steps. The authors call for (1) scaling up planting and mariculture, including genetic and microbial tools and assisted migration, such as moving heat-tolerant eelgrass from North Carolina to Chesapeake Bay; (2) early detection, using multi-stressor models, ocean models and regular monitoring of species mix, not just meadow area; and (3) governance that supports it, such as Virginia's seagrass carbon credit market, the first certified one.
What it means for Waquoit Bay today
The review is global, and most of its detailed examples come from Chesapeake Bay, the Virginia coast and Florida, not from southern New England. What carries over is the pairing it describes. Eelgrass in Waquoit Bay and across Cape Cod has declined sharply (see Cape Cod has lost about 90 percent of its eelgrass in a century), and cutting nitrogen is still the local lever the authors say comes first. Warming adds a second pressure that local cleanup cannot remove. A monitoring study from New Hampshire to Maryland found eelgrass was less likely to return after a hot summer (see Do hot summers cost us eelgrass the next year?), and Tampa Bay lost seagrass after its nitrogen cleanup as the water grew hotter and fresher (see Tampa Bay's seagrass loss).
For restoration planning here, the review's points on diversity and heat tolerance are worth watching, since the northwest Atlantic has few seagrass species that could fill in for eelgrass. Its calls for tracking species mix and for restoring at larger scale and with warming in mind match the pilot plantings of heat-tolerant plants now under way on the Cape. The review does not measure Waquoit Bay itself, so how these trends play out here remains to be seen.
Read the paper
Hensel, M. J. S., Patrick, C. J., Brown, C. J., Dunic, J., Lefcheck, J. S., Hensel, E., Nordlund, L. M., Wong, M. C., Carr, J. A., Dennison, W. C., Engelhardt, K. A. M., Kendrick, G. A., McGlathery, K., Zimmerman, R. C., Wilcox, D. J., & Orth, R. J. (2026). Climate change is reshaping seagrass futures: Novel environments and opportunities along coastlines and across oceans. *BioScience*, biag145. https://doi.org/10.1093/biosci/biag145
License: The article is open access under a Creative Commons Attribution 4.0 (CC BY 4.0) license, which allows reuse with credit. The PDF is hosted here under that license, and this summary is based on the full paper. The card image is a title card made from the citation.
Drafted with AI assistance from the linked source.
