Intraspecific Differences in Temperature and Salinity Responses in the Coccolithophore Emiliania huxleyi

AbstractThe growth responses of two clones of the oceanic coccolithophore, Emiliania huxleyi, isolated from the Sargasso Sea and the Hudson Canyon, were observed under 25 different salinity-temperature regimes. The temperature range studied was from 8 to 27°C; the salinity range was from 20 to 45 ppt. The isolate from the Sargasso Sea grew better at higher salinities than did the Hudson Canyon isolate, although not as well at the highest temperature. Generally, the Sargasso Sea clone had a narrower optimal temperature range (18–23°C) and wider salinity range than did the Hudson Canyon clone. The results suggest that, as with diatoms, physiologically distinct races exist in coccolithophores, as indicated by the intraspecific differences in growth response to temperature and salinity in E. huxleyi. Furthermore, the different growth responses of the two clones are consistent with the prevailing environmental conditions in their sites of isolation.