Do Developmental Stages of a Clinid Fish Larva Influence in Their Feeding Success in a Microtidal Estuary?

The utilization of estuaries as nursery zones for fish is widely known, but differences in the success of resource exploitation vary between resident and opportunistic estuarine species. The distribution and diet of larval Myxodes viridis (Pisces: Clinidae) were studied at 2 locations in the Corral Bay estuary, southern Chile, during the austral spring 2009 at 3 depths, during 4 tidal cycles. Larvae were collected mostly at down-estuary station during the ebb phase. Feeding incidence was greater during the ebb phase; larvae changed from omnivory to carnivory as they developed, predating mainly on nauplii and calanoid copepodites. Although the feeding success was similar for each developmental stage along the water column, diet of preflexion and flexion larvae was different in surface and pycnocline (3-4 m), in relation to deeper waters (7-10 m). This suggests that the pycnocline may affect the composition of the diet of small, larval M. viridis but not the size, number or volume of ingested prey. Foraging is predominantly based on the different life stages of copepods, larvae emerging during the ebb tide may increase the off estuary advection into nearby shelf waters, indicating that this species is not a user of the estuary during its early development.