Membranipora membranacea in the Gulf of Maine

Membranipora membranacea is an invasive bryozoan that was first seen in the Gulf of Maine at the Isle of Shoals in 1987.  Membranipora was most likely introduced by ships (on the hull or in the ballast water) from Europe. Within two years, Membranipora became the dominant species covering kelps and has since spread to many other seaweeds.  For more information on how Membranipora was able to spread so quickly and what the consequences are from this invasion, see the page on my research on this species.  Below are pictures of Membranipora taken around Bailey Island, Maine.

On Kelps (Laminaria saccharina)

On Rockweed (Fucus sp.)

On Red Seaweed (Palmaria palmata)

Membranipora Predators: Sea Slugs

Onchidoris muricata

Doridella obscura

More information on predation by Onchidoris can be found here.  I have only rarely seen Doridella eating Membranipora, but it is difficult to see as it is very well camouflaged.  According to Larry Harris (University of New Hampshire), Doridella obscura has not typically been found this far north as it seems to do better in warmer water.  Indeed, the only time of the year that I have seen Doridella is in the late summer and early fall when the water temperatures are warmer.

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