IN THE ESTUARIES of the Pacific Northwest, seagrasses grow in underwater meadows, perfect havens and nurseries for sea life. So far, seagrasses are holding their own against “macroalgaes” — large seaweeds that in some regions have bloomed wildly, smothering native species like eelgrass. A study of four Oregon and Washington estuaries (Coos, Yaquina, Netarts and Willapa bays) by OSU researcher Sally Hacker found stasis between the grasses and the weeds, perhaps because “tidal action and local currents are mediating the smothering effect” seen elsewhere. But she warns that climate-related changes to ocean upwelling “could have potentially profound effects on the future production” of Oregon’s estuaries.