Wednesday, May 5, 2010

Winchester Bay Invasive Tunicate Survey - April 26, 2010

On Monday, April 26th, 2010 an Oregon Coast Aquarium science diving team surveyed for invasive tunicates in Salmon Harbor at Winchester Bay, Oregon.  We selected some dozen sites within the harbor as well as the navigational markers at their entrances. Teams surveyed by shore and by boat.  Later in the day, three teams reinforced their training in Didemnum vexillum identification by viewing known examples on different portions of the oyster farm and rock jetty (south wall of the Winchester Bay jetty).

Lorne Curran: "No D. vex or any of the other 8-12 species that we monitor for could be found in Salmon Harbor or on the navigational markers outside of the harbor. Dock undersides had dense but simple fouling communities dominated by mussel (Mytilus sp.) with lesser amounts of small barnacle (Balanus sp.) On pilings the community profile was reversed with barnacles most in evidence. Most algae was filamentous with some rockweed and Ulva sp. Beyond these, none of the macro-algae common in the Triangle were found."

Salmon Harbor Marina had a strong halocline at around 5 foot depth.  Fresh water from the Umpua and a creek at the head of East Basin reduced salinity in this area.  Visibility in the marina was between 2 and 4 feet.  At The Triangle the water was very green with visibility around 2 feet.  A fresh gale wind and rain held throughout The Triangle dive.

The bad news (we already knew about): in The Triangle we found Didemnum vexillum, Botrylloides violaceus and Botryllus schlosseri in many locations.  Lorne Curran's observation (having dove this area several times previously): "I still see much greater biomass on the rocks than on the (oyster) infrastructure and, after this day, can add my impression that the colonies are rapidly developing. Where before I saw mostly one foot square colonies, I more often encounter colonies 2-3 feet square." 

Video of oyster rope bobbing with the wind waves

Dive team present:  Aquarium staff members Vallorie Hodges and Jim Burke.  Aquarium volunteers Jim and Chris Pendergrass, Lorne Curran, Dylan Curran, Ian Chun, Bruce Hansen, Galen Gard and John Estabrook.  ODFW's Scott Groth and his assistant Jim made smooth work of the boat operation.

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