# Climate change impacts on marine ecosystems > Live situation record from CLSTR: https://clstr.news/situations/climate-change-impacts-on-marine-ecosystems > Updated: 2026-09-06T23:12:59.000Z. Sources: 6. Developments: 2. Scientific research indicates that climate change is driving fundamental transformations across marine ecosystems, affecting biological communities from the microbial level to larger organisms. In the United States, the decline of kelp forests in Maine is causing a transition toward turf algae, which alters microbial communities and the chemical compounds they produce. In the UK and Irish waters, rising sea temperatures and changing ocean circulation are shifting plankton communities. Specifically, spring phytoplankton blooms in parts of the North Sea are occurring up to a month earlier than in the late 1990s, potentially creating mismatches with the life cycles of fish larvae, seabirds, and marine mammals. Further research suggests these environmental changes may significantly impact the physical size of marine mollusks by the year 2100. A study of over 23,000 species indicates that under high greenhouse gas emission scenarios, approximately two-thirds of analyzed mollusk groups and ocean regions could see significant size reductions. While average body length might decrease by up to 16%, the impact on total biomass could be much more severe. These shifts threaten to disrupt critical ecosystem functions, including nutrient cycling, carbon sequestration, and human food supplies. ## Timeline ### 2026-09-06: Climate change threatens to reduce marine mollusk sizes A PNAS study warns that climate change could cause significant size and biomass reductions in many marine mollusk species by 2100, potentially disrupting ocean ecosystems and food supplies. 4 sources. https://clstr.news/cluster/climate-change-threatens-to-reduce-marine-mollusk-sizes ### 2026-08-31: Marine ecosystems face shifts in microbial and plankton communities due to climate change Climate change is driving ecological shifts in marine environments, from microbial changes in Maine's collapsing kelp forests to altered plankton bloom timings in UK and Irish waters. 2 sources. https://clstr.news/cluster/marine-ecosystems-face-shifts-in-microbial-and-plankton-communities-due-to-climate-change --- Cite as: Climate change impacts on marine ecosystems. CLSTR, https://clstr.news/situations/climate-change-impacts-on-marine-ecosystems