Scottish Marine and Freshwater Science Vol 11 No 15

This report describes the opportunistic deployment of recording temperature loggers at the seaward and landward edges of a Scottish inter-tidal shellfish farm between October 2016 and May 2018. The farm, situated in Loch Creran, Argyll, cultures the Pacific oyster Crassostrea gigas (Thunberg, 1793). Additionally, the presence of the non-native invasive sea squirt Didemnum vexillum (Kott, 2002) has been recorded on the farm since 2015. Results presented here confirm that inter-tidal habitats periodically exposed to the air on the Scottish west coast experience greater temperature extremes than sub-tidal habitats which are only exposed to sea temperatures.

Two research priorities were identified during this study:

1) In order to be able to manage the risk of naturalisation of the Pacific oyster in Scottish waters, a priority research area is understanding the thermal conditions required for successful reproduction and recruitment using stock already exposed to Scottish conditions.

2) In order to understand the reproductive potential of Didemnum vexillum *in Loch Creran, research is needed into the potential development of larvae under local conditions, as well as the effect of exposure to high temperatures in air inter-tidally on the sexual development of *Didemnum vexillum.