Pacific lamprey (Entosphenus tridentatus) ammocoetes exposed to contaminated Portland Harbor sediments: Method development and effects on survival, growth, and behavior

Abstract

Many anthropogenic disturbances have contributed to the decline of Pacific lampreys (Entosphenus tridentatus), but potential negative effects of contaminants on lampreys are unclear. Lamprey ammocoetes are the only detritivorous fish in the lower Willamette River, Oregon, USA, and have been observed in Portland Harbor sediments. Their long benthic larval stage places them at risk from the effects of contaminated sediment. The authors developed experimental methods to assess the effects of contaminated sediment on the growth and behavior of field-collected ammocoetes reared in a laboratory. Specifically, they developed methods to assess individual growth and burrowing behavior. Burrowing performance demonstrated high variability among contaminated sediments; however, ammocoetes presented with noncontaminated reference sediment initiated burrowing more rapidly and completed it faster. Ammocoete reemergence from contaminated sediments suggests avoidance of some chemical compounds. The authors conducted long-term exposure experiments on individually held ammocoetes using sediment collected from their native Siletz River, which included the following: contaminated sediments collected from 9 sites within Portland Harbor, 2 uncontaminated reference sediments collected upstream, 1 uncontaminated sediment with characteristics similar to Portland Harbor sediments, and clean sand. They determined that a 24-h depuration period was sufficient to evaluate weight changes and observed no mortality or growth effects in fish exposed to any of the contaminated sediments. However, the effect on burrowing behavior appeared to be a sensitive endpoint, with potentially significant implications for predator avoidance. Environ Toxicol Chem 2016;35:2092-2102. © 2016 SETAC.

Responses of juvenile southern flounder exposed to Deepwater Horizon oil‐contaminated sediments

“…In the present study, fish in the higher exposure treatments may have altered their effective exposure to the contaminated sediments by spending more time in the water column, although this cannot be stated with any certainty because the experiment was not initially designed to test behavioral responses. However, these sorts of behavioral changes by benthic fish exposed to hydrocarbon contaminated sediments have been reported previously [38].…”

Lamprey (Entosphenus sp. and Lampetra sp.) estuarine occupancy is regionally variable and constrained by temperature

“…Our occupancy model identified a clear distinction among regions for juvenile lamprey (Figure ), which has implications for habitat quality. Lamprey are thought to be sensitive to contaminated sediments and poor water quality (Moyle, ; Unrein et al, ). Therefore, areas of the lower San Joaquin region, which should be continually seeded by spawning in the San Joaquin River (and its tributaries), may have particularly low benthic habitat quality (Brown, Thompson, Higgins & Lucas, ).…”