Publication Abstract

Feeding ecology of herring larvae in a turbid estuary, the Blackwater

C.J. Fox, R. Harrop and A. Winpenny

Most studies on feeding by herring larvae have taken place in the open sea. Within estuaries conditions are more tidally energetic with regular periods of increased turbidity and this is likely to affect the feeding success of fish larvae within these environments. Measurements of turbidity and underwater illumination in the Blackwater Estuary confirmed that tidally induced turbidity reduced the effective water depth in which herring larvae could visually feed by up to 50%. However, no clear relationship between feeding success and state of the tide could be demonstrated. Feeding success, as monitored by gut contents, appeared to be more strongly related to surface light levels and was only reduced significantly during periods of darkness. Concentrations of potential prey items in the water were in the range 6.0-49.7 organisms 1^-1 with a median concentration of 15 organisms 1-1 (n=26). Feeding herring larvae negatively selected the nauplii but positively selected the copepodite and adult stages of copepods. Gastropod larvae were also positively selected while polychaete larvae were ingested with neutral selectivity but cirripede nauplii were negatively selected. In terms of selection from the prey width spectrum, particles in the ranges 200-250 pm and 300-350 pm were preferred. These preferences were extricable terms of the prey types which were selected by larvae.

Reference:

C.J. Fox, R. Harrop and A. Winpenny, 1999. Feeding ecology of herring larvae in a turbid estuary, the Blackwater. Marine Biology, 134(2): 353-365