Apparent oceanographic triggers to the spawning of the limpet Lottia digitalis (Rathke)

• Published in: Journal of experimental marine biology and ecology 1998-04, Vol.222 (1), p.31-41
• Main Author: Shanks, Alan L
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Archaeogastropods; Biological and medical sciences; Demecology; Downwelling; Fundamental and applied biological sciences. Psychology; Larval dispersal; Limpets; Lottia digitalis; Spawning; Vertebrata
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/S0022-0981(97)00135-4

At South Cove, Cape Arago, Oregon, spawning by Lottia digitalis was monitored daily during the winters of 1995 and 1996. Sharp drops in a Gonad Index indicated that there was one spawning in February of 1995 and two in April of 1996. Each of the spawnings occurred when (1) the seas were relatively rough as indicated by total wave energy and significant wave height, (2) seawater temperatures were >11°C, and (3) salinity was relatively low (≤32.5). Periods of high temperature and low salinity tended to occur after strong winds from the south that, due to Ekman transport, generated downwelling. These results suggest that spawning occurred during rough seas associated with downwelling. Spawning in archaeogastropods during rough seas and downwelling has been reported a number of times in the literature. The consequences of spawning at these times may be that larvae are rapidly swept out of the surf zone by the stronger rip currents generated by large waves, but coastal currents and density structure associated with downwelling may maintain larvae relatively close to shore. The timing of spawning and the brief larval duration characteristic of species that spawn during rough seas and downwelling may have evolved to exploit oceanographic conditions that enhance the survival and settlement of their larvae.