Thursday, July 8, 2010

Marina Walkabouts from Coos Bay to Charleston - week of June 28th, 2010

Monday, Lorne Curran walked marinas and boat ramps starting from the town of Coos Bay and ending in Charleston. Thursday, Lorne, Sam Chan, Bruce Hansen, and ODFW biologist Scott Groth collected samples of known Didemnum vexillum colonies and deployed underwater surveillance systems to search for additional colonies.

Coos Bay town docks 43.36664 -124.21220. The small moorage only provides slips for about 30 boats. Two commercial fishing boats were tied up-one from invasive hot spot San Franscisco and one from Fort Bragg. Well within the mesohaline portion of Coos Bay, the brackish water supported light growths of barnacles and mussels, rockweed and filamentous algae, hydroids and an oyster, likely C. gigas.

North Bend boat ramp and boardwalk 43.40815 -124.21220. Moving closer to the marine-dominated portion of Coos Bay, barnacles and mussels thickly encrusted the sides of the dock along with hydroids and some invasive sponge. Rockweed, Ulva, some filamentous algae. No tunicates visible.

Empire boat ramp 43.39331 -124.128008. Well within marine-dominated waters, the same fouling community grew abundantly along with eelgrass in the shallows. Sculpins rested on the bottom in shallow waters, and young of year rockfish schooled in the hydroids blanketing the sides of the dock. The limitations of surveying from the top of docks became apparent as we know Botrylloides violaceus to grow subtidally on the pilings immediately north of the dock, but none was visible to the dockside observer.

Charleston Bridge. During a recreational dive here, B. violaceus was again noted, having been known for at least four years. Inspecting junk and shell substrate as well as the base of three sets of bridge pilings showed sponges both native and invasive, plumose anemones, and native tunicates but no certain sign of D. vex.

Charleston Small Boat Harbor. Large mussels and the native tunicate Corella inflata along with other typical fouling organisms grow on the underside of docks. Unfortunately, invasive tunicates Styela clava, B. violaceus, and Botryllus schlosseri thrive here as well. Invasive sponge takes on a curious pink shade as well as do the more usual yellow-colored colonies. Thursday's team viewed D. vex colonies on an Oregon Institute of Marine Biology's settling substrate and collected sponge and B. violaceus for pharmaceutical research at OSU.

Charleston Commercial Boat Harbor. Two tires suspended in one meter of water as impromptu settling plates have supported D. vex for several months.The rest of the day, people split into two groups, each with an underwater surveillance system to survey for additional D. vex infestations under docks, on pilings and under boats. Bruce and Lorne covered much of the two southerly docks while Sam and Scott ranged more widely in a boat. With the exception of a possible colony on a Coast Guard boathouse piling, no more was discovered. This at least suggests the local infestation has been recent, not yet reaching the phase of explosive growth.

No comments:

Post a Comment