Hypoxia in Chesapeake Bay Tributaries: Worsening effects on Macrobenthic Community Structure in the York River

Abstract

We assessed the effects of hypoxia on macrobenthic communities in the York and Rappahannock Rivers, Chesapeake Bay, in box-core samples before and after hypoxic episodes in 2003 and 2004. Hypoxia occurred in both years and was associated with a decrease in biomass and a shift in community structure toward opportunistic species in both rivers. Long-term data indicate that the frequency of hypoxia in the York has increased over the last 22 years. In previous work from ∼20 years ago, the macrobenthic community structure did not change in response to hypoxia in the York; however, in the present study hypoxia was associated with a reduction in community biomass and a change in community structure. We conclude that currently hypoxia is a more important environmental problem in the York than in previous years. Hypoxia likely negatively affects the estuarine food web, as lower macrobenthic biomass could decrease food availability to epibenthic predators.

Effects of anthropogenic shoreline hardening and invasion by Phragmites australis on habitat quality for juvenile blue crabs (Callinectes sapidus)

“…Parameters organisms is similar to what occurs in Chesapeake Bay under stressors such as hypoxia (Llansó, 1992;Long and Seitz, 2009). The lower density and shift in community structure did not have a significant effect on juvenile blue crab feeding.…”

Declining impact of an introduced pathogen: ­Haplosporidium nelsoni in the oyster Crassostrea virginica in Chesapeake Bay

“…As eutrophication of Chesapeake Bay has increased (Kemp et al 2005), large, long-lived benthic fauna have declined. Smaller, shorter-lived, opportunistic species are more abundant in today's more degraded Chesapeake Bay (Holland et al 1987, Long & Seitz 2009). The intermediate host(s) for Haplosporidium nelsoni that have been hypothesized to exist (Haskin & Andrews 1988) but which have not yet been identified may be among these thriving opportunists.…”

Short-term effects of nereid polychaete size and density on sediment inorganic nitrogen cycling under varying oxygen conditions

“…Depending on the timing and duration, hypoxic events may have a large impact on chemical equilibria, microbial activity, and macrofaunal physiology; however, effects may not be severe enough to kill off macrobenthic populations (Meyer-Reil & Koster 2000). As O 2 was depleted from the overlying water to below 94 µM O 2 , worms migrated closer to the surface, maintained their irrigation rates, but reduced burrow construction and ingestion (Long & Seitz 2009). Once the overlying dissolved O 2 reaches 63 µM O 2 or lower, polychaetes stop constructing burrows, decrease their burrow ventilation and migrate closer to the sediment surface (Diaz & Rosenberg 1995).…”