Temperature responses of tropical to warmtemperateCladophora species in relation to their distribution in the North Atlantic Ocean

• Main Authors: Cambridge, M. L., Breeman, Anneke M., Kraak, Sarah B. M., Hoek, Christiaan van den
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1987
• Subjects: Text; North Atlantic
• Online Access: https://www.openagrar.de/receive/timport_mods_00037012; https://www.openagrar.de/servlets/MCRFileNodeServlet/timport_derivate_00037012/dn054959.pdf

The relationship between distribution boundaries and temperature responses of some North Atlantic Cladophora spedes (Chlorophyta) was experimentally examined under various regimes of temperature, light and daylength. Experimentally determined critical temperature intervals, in which survival, growth or reproduction was limited, were compared with annual temperature regimes (monthly means and extremes) at sites inside and outside distribution boundaries. The species tested belonged to two phytogeographic groups: (1) the tropical West Atlantic group (C. submarina: isolate from Curacao) and (2) the amphiatlantic tropical to warm temperate group (C. prolifera: isolate from Corsica; C. coelothrix: isolates from Brittany and Curacao; and C. laetevirens: isolates from deep and shallow water in Corsica and from Brittany). In accordance with distribution from tropical to warm temperate regions, each of the species grew well between 20-30 °C and reproduction and growth were limited at and below 15 °C. The upper survival limit in long days was< 35 °C in all species but high or maximum growth rates occurred at 30 °C. C. prolifera, restricted to the tropical margins, had the most limited survival at 35 °C. Experimental evidence suggests that C. submarina is restricted to the Caribbean and excluded from the more northerly American mainland and Gulf of Mexico coasts by sporadic low winter temperatures in the nearshore waters, when cold northerly weather penetrates far south every few years. Experimental evidence suggests that C. prolifera, C. coelothrix and C. laetevirens are restricted to their northern European boundaries by summer temperatures too low for sufficient growth and/or reproduction. Their progressively more northerly located boundaries were accounted for by differences in growth rates over the critical 10-15 °C interval. C. prolifera and C. coelothrix are excluded or restricted in distribution on North Sea coasts by lethal winter temperatures, again differences in cold tolerance accounting for differences in ...