Final answer:
European green crabs, an invasive species, disrupt US ecosystems by outcompeting and preying on native species, leading to significant reductions in local biodiversity and imbalances in marine food webs.
Step-by-step explanation:
European green crabs, introduced to San Francisco Bay in the 1990s and spreading along the coast, pose a significant threat to US ecosystems. These invasive species compete with native crabs and clams, dramatically reducing their abundance. By preying on native species and outcompeting them for resources, European green crabs disrupt local marine food webs and biodiversity, leading to ecosystem imbalances. This can result in increased prey numbers of native crabs, which further stresses the ecological equilibrium.
The success of green crabs as an invasive species lies in their reproductive efficiency and adaptability, allowing for rapid colonization and dispersal. Without immediate eradication efforts or management strategies, the continued spread of these crabs can have lasting negative impacts on native communities and the overall health of marine ecosystems.