Exposure to acute low pH impairs chemoreception and feeding performance in larval fathead minnows (Pimephales promelas)

Abstract

The impact of acute low pH exposure on feeding performance was investigated in larval fathead minnows. Sets of larvae were subjected to each of three pH concentrations (4.5, 5.5 and 7.7) under various conditions designed to isolate different sensory modalities. Temporal patterns in locomotor activity and number of larvae feeding were analyzed. Levels of locomotor activity were uncorrelated with feeding rates and were qualitatively different early vs. late in the larval phase. Under most conditions, locomotor activity decreased during the first few days posthatching, then increased over the remainder of the study. In contrast, feeding activity increased continually. Mechanoreception appeared to play a significant role in prey capture at pH 7.7, while photoreception contributed little. pH exposure had a significant negative impact on feeding success, though the nature of this effect varied with test conditions. Exposure to pH 4.5 appeared to strongly inhibit chemoreception; data also suggest close coupling of chemoreception and mechanoreception. These results point to the necessity for studies of acidification effects on larvae and suggest an approach by which aspects of sensory integration may be dissected.

Key words:

• pH exposure
• chemoreception
• feeding
• locomotor activity
• larvae
• ontogeny

Notes

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