Cj. Sorte et al., Larval dynamics of the sand crab, Emerita analoga, off the central Oregon coast during a strong El Nino period, J PLANK RES, 23(9), 2001, pp. 939-944
Populations of the sand crab, Emerita analoga, are well established on the
California coast. However, populations in Oregon occur sporadically and app
ear to be restocked by larvae drifting north from California. Due to increa
sed northward transport in winter during El Nino events, we would expect th
at larval recruitment to northern populations should be higher during these
periods. This hypothesis was tested by comparing larval abundances between
non-El Nino and El Nino years, 1997 and 1998, respectively. In 1997, larva
l abundances and seasonality were similar to historical data from 1969-71.
First zoeal (Z1) stage larvae were present during these summers, but in low
numbers, indicating th at E. analoga spawned off the coast of Oregon. In 1
998, strong larval recruitment from the south occurred, demonstrated by a l
arge number of fifth zoeal stage (Z5) larvae collected off Oregon in April
and May. The large numbers of Z1 found in summer 1998 indicate that the Z5,
which arrived from, California earlier that spring, successfully recruited
to adulthood and reproduced. These data indicate that Oregon E.analoga pop
ulations are probably dependent on larvae travelling from California in the
Davidson Current. It follows that this species could be used as an indicat
or of coastal current fluctuations such as those seen during El Nino events
.