Friday, June 4, 2010

Yaquina Bay Invasive Tunicates Survey - May 30, 2010

Four divers from the Oregon Coast Aquarium surveyed the southwest tip of the LNG tank peninsula. They found the invasive tunicate Molgula manhattensis growing abundantly on the bottom of the spud barge moored there.

View Yaquina Bay LNG Tank Waterfront in a larger map

Report from John and Lorne. Beginning on the north side of the barge, they swam the perimeter observing invasive sponge and macro-algae growing well in the sunlight with native YOY rockfish sheltering in the habitat. Ducking under two thirds of the way out, the divers found the fouling community on the underside of the barge dominated by what they thought to be hydroids gowing on and among many Molgula. Invasive sponge and mussels were prominent but lesser in number.

Molgula grew some dozen in each clump with many individuals scattered closely by. With smaller ones also apparent, the larger specimens ranged from 14 mm to 24 mm measured transversely. The divers saw the tunicate everywhere they checked under the barge. Despite Molgula being common in Coos Bay to the south, this represents the first sighting in Yaquina Bay in five underwater surveys and several above water marina inspections.

What appears to be pilings, the "spuds" were clean, not surprising as the spud barge lowers these from the hull to moor itself.

Proceeding south along the riprap, John and Lorne found the rocky substrate to be largely limited to the intertidal. Macro-algae predominated. Two native monkeyface pricklebacks hid in crevices. The divers neglected to check clumps of eelgrass for fouling tunicates.

Bruce and Nate surveyed from the point eastward, likewise finding mostly macro-algae. They descended to twenty feet in their search.

Aquarium staff participating in this survey were Nate Carpenter, aquarist, surveying, and Vallorie Hodges, dive safety officer, tending. Aquarium volunteers John Estabrook, Bruce Hansen, and Lorne Curran surveyed, with Dylan Curran tending.

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