The Influence of Body Size, Temperature and Aerial Exposure on the Reproduction and Survival of an Invasive Sea Anemone
The invasive Asian sea anemone Diadumene lineata occurs in both subtidal and intertidal environments, the latter including mudflats, salt marshes and pier pilings. In this project a series of experiments were conducted examining the effects of body size, temperature and aerial exposure on this anemone's survival and reproduction. Greater proportions of anemones exposed to warmer temperatures (18°C and 25°C) reproduced through asexual binary fission, a longitudinal division where one anemone splits into two, than anemones exposed to cool temperatures (12°C). When exposed to air for up to 24 hours, anemones with basal diameters greater than 4 mm survived significantly longer exposures than smaller anemones (< 4 mm). In addition, anemones under both aerial exposure and one of three experimental temperatures (12°C, 18°C and 25°C) did better in cold versus warm conditions—those exposed to fluctuating emersion/immersion (12 h/12 h) periods at 12°C survived while those under the same fluctuating emersion cycle at 18°C and 25°C did not. Some of the anemones under cyclical exposures formed mucous capsules, a previously known survival strategy for stressful conditions (Miyawaki, 1951). These results suggest that subtidal populations of D. lineata are most likely to spread and increase their population sizes during summer, when temperatures encourage high rates of binary fission. Intertidal populations of D. lineata, however, are most likely to endure as large adults under cooler temperatures. Although D. lineata is reported to occur in a broad range of temperatures from cold water to tropical environments, we predict that populations living in the North will be found in both the intertidal and subtidal zones, while temperature conditions at low latitudes may prove too challenging for intertidal populations, while encouraging the spread of subtidal populations.