Aliens, exotics, introductions, invaders...
They can damage native plants, birds, fish, and mammels and disrupt the very natural world we paddle out to enjoy. The good news is that kayakers in particular can help marshal the defenses againest them.

No, it's not the latest summer blockbuster. The sacred haunts of the kayaker are being invaded. This is not the familiar invasion of fellow paddlers (a mixed blessing), but a new and more insidious invasion by other species altogether.
Cruise along the northern Mediterranean coast, and you will find that the shallow sea-grass beds that once teemed with life are now a desert of "killer" green algae, devoid of fish and invertebrates. From British Columbia to California, tranquil estuaries that echoed with flocks of migrating birds are now overgrown with acres of new salt marsh, obscuring the shoreline from birds and boaters alike. Along the volcanic rocky shores of Hawai'i, a new barnacle has taken up residence; the coast of South Africa is being invaded by an aggressive intertidal mussel; New Zealand and Australia are unwilling hosts of new seaweeds. Almost everywhere we paddle, old species are being swapped for new.
But new is not necessarily better.
Aliens, exotics, introductions, invaders…they go by many names, but all of these species share the common trait that they are spreading to places they don't belong. They not only affect kayakers, but snorkelers, scuba divers, fishers, clam diggers, and other boaters. They can carry parasites and diseases. (Some of them are parasites and diseases.) They can damage fisheries, tourism, boating, property values, and industry. They can damage native plants, birds, fish, and mammals and disrupt the very natural world we paddle out to enjoy. That's the bad news. The good news is that kayakers in particular can help marshal the defenses against them.

(photo:In the Pacific, smooth cordgrass spartina alterniflora was first discovered in Willapa Bay, Washington, in the late 1800's)