Cold-Temperate Seaweed Communities of the Southern Hemisphere - Seaweed Biology - page 287

around 36 S in an area called the Brazil/Falkland Confluence (Acha et al. 2004 ;
Fig. 14.1 ). The cold-temperate section of the southeastern South America (approx-
imately 41-55 S) is characterized by large bays and harbors, which provide hetero-
geneous habitats for seaweeds. Northwards of the Gulf San Mat ´ as (41 S),
temperature increase and substrate become less suitable for seaweeds due to the
massive runoff and sedimentation from Rio de la Plata (Acha et al. 2004 ). The
Falkland Islands (Islas Malvinas), with sub-Antarctic characteristics, are situated in
the path of the Falkland Current (Fig. 14.1 ) with water temperatures around 3-14 C
(see also Chap. 18 by Bartsch). The coastal oceanography is characterized by the
two branches of the Falkland Current, the weaker western branch (the Patagonian
Current) rejoining the eastern branch north of the islands (Upton and Shaw 2002 ).

14.1.3 Victoria-Tasmania Region

The warm East Australian Current is the largest and the warm Leeuwin Current the
second largest ocean current in Australia. The Leeuwin Current flows from the west
Australian coast towards south-east, becoming the South Australia Current as it
flows across the Great Australian Bight, reaching the west Tasmanian coast as the
Zeehan Current (Fig. 14.1 ). The importance of these currents is evident from
the tropical elements present in southern Australian waters at temperate latitudes.
The southern coast of Tasmania is situated a few degrees north of the STF, the limit
of sub-Antarctic waters (summarized by Poloczanska et al. 2007 ). However, in the
coasts of Tasmania and Victoria, the surface water temperature remains cool,
generally not exceeding 15 C in summer (L uning 1990 ; see also Chap. 18 by

Bartsch). The southern Australian coastline has large sections of rocky substrata,
providing suitable habitats for seaweeds (Phillips 2001 ).

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14.1.4 Southern New Zealand Region

Subtropical waters with relatively high salinity and temperature around New
Zealand are mainly derived from the East Australian Current, while sub-Antarctic
waters, with relatively low salinity and temperature, are driven north by the ACC.
These two water masses meet in the STF (following roughly the 10 C winter and the
15 C summer surface isotherm; see also Chap. 18 by Bartsch). Along the east coast
of the South Island, the Southland Current brings cool water towards north. It turns
towards east and back to south around 40 S (Cape Turnagain), the northern limit for
many species, combining with the warmer East Cape Current (Heath 1985 ; Parsons
1985 ) (Fig. 14.1 ). In the Fiordland region of the South Island, the exposed coastline
is interrupted by channels, inlets, fjords, and many estuaries. Thus, the littoral
systems in these locations are strongly influenced by the inflow of freshwater from
rivers and glaciers (Nelson et al. 2002 ).