| Popis: |
Decapod crustacean larvae were sorted from plankton samples collected between Arica (18° 30' S, 70° 20' W) and Huasco (28° 30' S, 71° IS' W), a distance of about 1,050 km along the northern coast of Chile, from February 19 to March 28, 1983, during this century's strongest recorded El Nino event. The samples were taken from 11 east-west transects extending from near the coast (5 km offshore) to approximately 200 km offshore, each with 4 stations approximately 65 km apan. Larvae (nauplius, protozoea, zoea, or megalopa) from 22 species (17 genera, 15 families) were collected; most larvae were zoeae. Of the zoeal larvae, 1.8% were Dendrobranchiata and 98.2% were Pleocyemata. Among the Pleocyemata, the Brachyura were most abundant (88.0%), followed distantly by Anomura (9.9%), Caridea (1.8%), and Thalassinidca (0.2%). Grapsid and pagurid larvae were most numerous within the Brachyura and Anomura (respectively) and were the dominant taxa at coastal stations. The number of species found (22) is far fewer than the normal stock of 139 species (94 genera, 38 families) of decapod crustaceans recorded as adults for this area of northern Chile, although the lack of earlier sampling efforts precludes comparison with decapod larval fauna of non-El Nitio years. Protozoeae and zoeae of oceanic species of the genera Xiphopenaeus (Fenaeidae) and Sicyonia (Sicyoniidae), not previously recorded from Chilean watei^, were also found. The presence of larvae of these tropical oceanic genera, and the high ratio in which other tropical families and species appeared, may be due to the effects of the strong El Nitio event. |
