The distribution of benthic marine algae in relation to the temperature regulation of their life histories

摘要: Mainly on the basis of distribution patterns 42 species recently revised genus Cladopkora (Chlorophyceae) in north Atlantic Ocean, it appeared possible to distinguish 10 phytogeographic groups wide applicability. Experimentally determined critical temperatures limiting essential events life histories 17 benthic algal were used infer boundaries; these fit closely boundaries derived from field-distribution data. For a temperate species, at least six different can be postulated and should checked northern hemisphere: (1) ‘northern lethal boundary’ (corresponding lowest winter temperature which survive); (2) growth summer which, over period several months, permits sufficient growth); (3) reproductive permitting reproduction months); (4–6) corresponding southern boundaries. Photoperiodic responses may influence responses. Many appear composite nature. instance, boundary Laminaria digitata follows European 10°C February isotherm (which corresponds highest fertility female gametophyte, i.e. ‘southern boundary’), American 19°C boundary’). Thus, experimental evidence supports validity eight following (for 2 6, such could not found): amphiatlantic tropical-to-warm group, with north-eastern extension (examples: Gracilaria foliifera Centroceras clavulalum); north-western (example: Hypnea musciformis); tropical-to-temperate group Sphacelaria rigidula =furcigera); (4) group: Cladophora rupestris type Callithamnion hookeri, Dumontia contorta; saccharina is transitional 10, I., types 5 10); (5) Cl. albida Scytosiphon lomentaria, Petalonia fascia); (6) tropical western group; (7) north-east tikvahiae); (8) Japanese Campylaephora hypneoides Sargassum muticum); (9) warm-temperate Mediterranean-Atlantic Californian Saccorhiza polyschides, hyperborea, ockroleuca, Macrocystis pyrifera, Hedophyllum sessile); (10) Arctic dermatodea arctica). Distribution 9 have comparatively narrow ranges span 18 22°C between their 12°C or These limit tropics; coasts eastern sides Pacific Oceans hemisphere; Arctic, respectively. The make this unfit for Oceans, where algae must cope annual fluctuations more than 20°C. Conversely, 8 (containing numerous endemic species) are characterized by spans (e.g. 29°C ‘lethal boundaries’, 12–19°C ‘growth and/or boundaries’) potentially capable occupying latitudinal belts along east Oceans. Algae ‘escaped’ Japan, as muticum, conform picture. Apparently do capacity long distance dispersal. (30–45 N) harbour very few probably result adverse nature sediment macroalgae functioning barrier displacements flora during glaciations. The remaining (1,2,3,4,5,7) distributions, often both hemispheres. Six (in 4, 9) an amphiaequatorial similar winter-temperature maxima isotherms 15–17°C; upper dissimilar correspond 20–30°C. Their explained assuming glacial drops equatorial intensified upwelling presumably circulation ocean gyres.