Cold-Temperate Seaweed Communities of the Southern Hemisphere - Seaweed Biology - page 285

Chapter 14
Cold-Temperate Seaweed Communities
of the Southern Hemisphere

Pirjo Huovinen and Iv´nG´mez

14.1 The Regions and Their Basic Abiotic Conditions

In the southern hemisphere, two circumpolar fronts roughly define the boundaries
of the cold-temperate region (Fig. 14.1 ). The southern limit, the Antarctic Polar
Front (APF; also known as Antarctic Convergence), is characterized by cold
(ranging 3-5 C) surface waters. The northern limit, the Subtropical Front (STF;
also known as Subtropical Convergence), separates subtropical water in the north
from sub-Antarctic water, and follows approximately the 10 C surface isotherm in
winter and the 15 C surface isotherm in summer (Heath 1985 ; Parsons 1985 ;
L uning 1990 ; see also Chap. 3 by Eggert and Chap. 18 by Bartsch). The STF is a

complex, irregular frontal zone with seasonal migration of up to 2 latitude (Nelson
and Broom 2010 ). The large eastward-moving Antarctic Circumpolar Current
(ACC; called also West Wind Drift) strongly determines the oceanography in the
Southern Hemisphere (Orsi et al. 1995 ) (Fig. 14.1 ). The circulation of the ACC and
circumpolar frontal zones strongly define the diversity, biogeography, and the
ecology of seaweeds in all the adjacent coastal regions.

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14.1.1 Southwestern South America Region

In the Southeastern Pacific coast of Chile, there are two major current systems, the
southward Cape Horn Current and the northward Humboldt Current, derived from
the ACC around 40 S (Fig. 14.1 ). In the south, the Cape Horn Current flows through
the Drake Passage. Three major regions along the coast can be identified: the

P. Huovinen ( * ) • I. G´mez
Instituto de Ciencias Marinas y Limnol´gicas, Universidad Austral de Chile, Campus Isla Teja s/n,
Casilla 567, Valdivia, Chile
e-mail: [e-mail]