Detection of the tropical mussel species Perna viridis in temperate Western Australia: possible association between spawning and a marine heat pulse.

In April 2011 a single individual of the invasive mussel Perna viridis was detected on a naval vessel while berthed in the temperate waters of Garden Island, Western Australia (WA). Further examination of this and a nearby vessel revealed a small founder population that had recently established inside one of the vessel's sea chests. Growth estimates indicated that average size mussels in the sea chest were between 37.1 and 71 days old. Back calculating an 'establishment date' from these ages placed an average sized animal's origins in the summer months of January 2011 to March 2011. This time period corresponded with an unusual heat pulse that occurred along the WA coastline resulting in coastal waters >3 ºC above normal. This evidence of a spawning event for a tropical species in temperate waters highlights the need to prepare for more incursions of this kind given predictions of climate change. [ABSTRACT FROM AUTHOR]