A biological study of Durvillaea antarctica (Chamisso) Hariot and D ...

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its northern liroi t varies between O-lOoS 1/Jhere it swings wes'l"Ward
to join the South Equatorial Current.
At about 28°s the Peru Current is disrup'ced by areas of coastal
upwelling from moderate depths (100-300 m). This upt-Telling .Le
greatly influenced by coastal winds I and subsidence may OCCllr when
there are strong onshore winds (Sverdrup et al. 1942). When this
happens, wa;cm tropical lilater moves south inside the Peru Coastal
CurrenL 'I'his means that although mean sea surface temperatures
may be about the same north of 28°5 as in areas wbere DuY'vilZaea
grows, maximum temperatures are much higher than may be tolerated by
the kelp. Sea temperature at Antofagasta occasionally reaches 26°Co
l~e
northern Chile coastal lands are hot dry desert, and it
is possible that conditions north of Coquimho are too severe for D.
an taY'ctica at lov! tide.
The diversity and abundance of Parrot fish increases towards the
tropics. According to Paine (pers.corom.) large parrot fishes are
abundant in norther Chile - much more so than in the central or
southern region. It is conceivable that grazing by these large
fish may prevent D. antarctica from becoming established north of
Coquimbo.
(b)
Fernandez I
These islands are several hundred km south of the northern
limit of D. antarctica in Chile" According to Sverdrup et al.
(1942:702) the western limit of the Peru Current system at the latitude
of these islands is about 900 km off the coast O.t about 35°S. Mas
a Tierra and Mas a Fuera Is are 650 and 825 kID from the coast
respectively. Plate (1896) claimed that the islands lay outside the
influence of the current. They are certainly far b"-,,ond the influence
of. the narrow Peru Coastal current.
Consequently sea temperatures {February :20-21