Effects of low dissolved oxygen on predation on estuarine fish larvae

Abstract

Low dissolved oxygen concentrations, caused by density stratification of the water column and excess nutrient inputs, occur in many aquatic habitats. Laboratory experiments we conducted indicated that low dissolved oxygen has the potential to strongly alter the absolute and relative importance of a suite of estuarine predators of fish larvae. At dissolved oxygen concentrations 22 mg l-', predation on naked goby Gobiosolna bosc larvae by an important invertebrate predator of plankton in Chesapeake Bay [the sea nettle scyphoinedusa Chrysaora quinqueclrrha) increased. In contrast, at the same oxygen concentrations, predation by 2 vertebrate predators, juvenile striped bass Morone saxatllis and adult naked goby, decreased. Changes in consumption of larvae most likely resulted from impaired ability of larvae to escape the scyphornedusa, and decreased attack rates by adult and juvenile fishes. Fish predators increased gill ventilation rates even at oxygen levels higher than those leading to decreased predation. However, we could detect no comparable change in behavior of the sea nettle even at 1 mg 1-', the lowest oxygen concentration tested The observed changes in trophic interactions occurred at dissolved oxygen concentrations that are not lethal during short exposures, and that commonly occur in the Chesapeake Bay and other eutrophic estuaries during summer. Thus, low oxygen has the potential to cause significant changes in the importance of alternate trophic pathways in estuarine systems.

Non-size-selective predation on fish larvae by moon jellyfish Aurelia aurita under low oxygen concentrations

“…These observations show that moon jellyfish of the genus Aurelia are highly tolerant to low oxygen concentrations, as are several other jellyfish species (Breitburg et al 1994, Keister et al 2000, Thuesen et al 2005 and indicates that the relative importance of trophic flow from fish larvae to moon jellyfish may increase due to changes in predator-prey interactions during summer hypoxia in coastal waters.…”

“…Declines in dissolved oxygen to moderate levels of hypoxia (ca. 1-2 mg L Ϫ1 ), which is not lethal during a short-term exposure, can reduce larval ability to escape from predators and increase mortality due to predation (Breitburg et al 1994, Shoji et al 2005a). …”

The effect of progressive hypoxia on school structure and dynamics in Atlantic herringClupea harengus

“…Direct and indirect physiological responses to hypoxia in fishes are well documented and the effect of hypoxia may include species-specific impacts on fish distribution, behaviour, feeding rate, competition and vulnerability to predators (Burton et al 1980;Coutant 1985;Kramer 1987;Pihl et al 1991Pihl et al , 1992Breitburg 1992;Breitburg et al 1994). Hypoxic conditions are usually found in coastal areas, and both benthic and pelagic fishes may be subject to hypoxia at some time during their lives.…”

Sea anemones and brittle stars: unexpected predatory interactions during induced in situ oxygen crises

“…Large foragers can migrate into and out of hypoxic areas and thus increase their predation eYciency (Pihl et al 1992). If, however, both predators and prey are aVected, then relative tolerance will govern predation eYciency (Breitburg et al 1994). Nestlerode and Diaz (1998) suggested that relative hypoxia tolerance might lead to selective predation on certain taxa, whereby the most intolerant prey will be exploited (Sandberg 1994).…”

“…They may also alter predator-prey interactions, whereby predation rates increase or decrease (e.g. the Xounder Platichthys Xesus: Tallqvist et al 1999) depending on the relative tolerances of predator and prey to anoxia (Breitburg et al 1994). Some marine predators even switch their prey items to optimally exploit the prey most sensitive to low oxygen concentrations (Sandberg 1994).…”