Tracking oxy-thermal habitat compression encountered by Chesapeake Bay striped bass through acoustic telemetry

摘要

In many coastal ecosystems, habitat compression is caused by seasonal combinations of hypoxia and supraoptimal temperatures. Theseconditions commonly induce avoidance behaviours in mobile species, resulting in the concentrated use of marginal habitats. Using 3 years ofacoustic telemetry and high-resolution water quality data recorded throughout Chesapeake Bay, we measured the seasonal movements andexposure of striped bass (Morone saxatilis) to oxy-thermal habitat compression. Striped bass moved to tidal freshwaters in spring(March–May), mesohaline waters in summer (June–August) and fall (September–November), and mesohaline and polyhaline waters in winter(December–February): seasonal patterns consistent with known spawning, foraging, and overwintering migrations. Analyses of habitat selectionsuggest that during conditions of prevalent sub-pycnocline hypoxia (June–September), striped bass appeared to select surface waters (i.e.they may avoid bottom hypoxic waters). Striped bass detections indicated tolerance of a wide range of surface water temperatures, includingthose >25°C, which regional regulatory bodies stipulate are stressful for this species. Still, during summer and fall striped bass selected thelowest-available temperature and avoided water temperature >27°C, demonstrating that Chesapeake Bay striped bass can encounter habitatcompressions due to the behavioural avoidance of bottom hypoxia and high temperatures.