Out of the Blue: The Failure of the Introduced Sea Anemone Sagartia elegans (Dalyell, 1848) in Salem Harbor, Massachusetts.

Abstract

Failed invasions can be a key component for understanding and controlling introduced populations because understanding mechanisms behind failures can improve effective controls. In 2000, the non-native sea anemone Sagartia elegans was first found in Salem, Massachusetts, and it recolonized each summer. No individuals of S. elegans have been found after 2010, despite intensive search efforts. A mismatch between the species' thermal tolerance and winter water temperature is the most likely mechanism for this failed invasion. In both laboratory- and field-based temperature growth studies, S. elegans began regressing at 11 °C, stopped asexually reproducing at 9 °C, and died by 4 °C. These temperatures are above the average winter sea surface temperature in the Gulf of Maine, therefore suggesting that S. elegans requires a warm-water refuge. Another potential contributor to the disappearance of S. elegans is low genetic diversity as a result of establishment of only females (likely clones) and no males.