T6 AM Environmental Hypoxia
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 324-326

(RIP-1117-660338) Eavesdropping on pipefish dinner conversation - a novel measure to assess hypoxia.

Ripley, Jennifer¹, Foran, Christy¹, ¹ West Virginia University, Morgantown, WV, USA

ABSTRACT- This research proposes to utilize the acoustical behavior of two sympatric pipefish species from the Chesapeake Bay as an indication of ecosystem activity and health. No environmental variable of such ecological importance to estuarine and coastal marine ecosystems has changed so drastically, in such a short period of time, as dissolved oxygen. Hypoxic, or low dissolved oxygen, events are severe in the Chesapeake Bay. Oxygen concentrations seasonally decline to anoxic levels, impacting populations by decreasing growth rates, altering behavior, disrupting the endocrine system and interfering with physiological activities. Pipefish were selected for study because they are abundant inhabitants of eelgrass beds (Zostera marina) during the summer months. Thus, they occupy the same area used as nursery grounds by many commercially important fish and shellfish species and their residency overlaps with the period of hypoxia problems. We collected Northern, Syngnathus fuscus, and Dusky pipefishes, Syngnathus floridae, from the relatively pristine Chincoteague Bay, Virginia and audiovisually recorded feeding behavior in the laboratory of fish held in normoxic (>5 mg/L O₂) and hypoxic (2 mg/L O₂) conditions for five days. The production of high frequency (0.9-1.6kHz), short duration (5-43msec) sounds by both species indicate sounds are generated by stridulation or the striking together of hard parts such as two bones. Sound production coincides with feeding strikes and wet weight of ingested food. Thus, sound production serves as an accurate measure of feeding activity. Under hypoxic conditions, reduced food intake correlates with decreased sound production. A drop in food intake and acoustical behavior is evident after only 24 hours of hypoxia exposure. Reductions in feeding will ultimately impact growth and health and eventually reproductive output as resources are devoted to survival instead of gamete production. This work suggests a novel technique to acoustically monitor field sites to assess ecosystem changes.

Key words: hypoxia, sound production, Chesapeake Bay, feeding behavior