Introduction to Model Behavior

All these movies are run under a Short hypoxic duration, 45% maximum hypoxic extent. The portion of the Neuse River estuary modeled is ~35km long and at most 8 km wide and less than 7m deep. Each movie consists of a series of panels where the number in the top right of each panel is the year. Thus, 39.50 corresponds to July 1 of 39^th simulation year, 39.60 to August 8, etc.

Environment Movie: Temperature, Depth, Salinity and DO

In the early spring and early winter, the lowest temperatures were found along the shoreline while the highest temperatures occurred in deeper areas. In summer, this pattern was reversed with the deeper parts of the estuary being cooler than the shallower shoreline. Depth remained constant throughout all simulations. Gradual increases in salinity can be observed towards summer, with the greatest salinities always occurring near the mouth of the estuary. The lowest salinities occurred along the shoreline, and decreased gradually away from the mouth of the estuary. Parts of the estuary became hypoxic at 39.33 (~May 1) and a number of small hypoxic patches formed by 39.465 (June 19) and moved around the estuary. The duration and dynamics of these patches is highlighted in these snapshots. Typically, deeper areas remained continuously hypoxic for less than 9 days and were more frequently hypoxic than shallower areas. Hypoxia had mostly dissipated by 39.80 (Oct 19).

Clams and Background Movie

The distribution of both clam and background prey biomass (g/m^2) was spatially variable over the estuary. Generally, deeper areas located near the estuary mouth contained less biomass. Clam density, however, was spatially uniform, except for the deepest and shallowest part of the Neuse. The clam recruitment events (one in spring, one in fall) are evident by the sudden pulsed increase in clam density at these times. Following clam recruitment, hypoxic exposure lead to rapid decreases in clam density.

Crab Density and Biomass Movie

The density (#/m^2) of 7-12 instar crabs was greatest along the shoreline towards the mouth of the estuary, but decreased over time till 39.6 (August 7) when density increased due to 7^th instar recruitment. These juvenile crabs quickly aggregated along the shores of the estuary. The density of 13-17 instar crabs was greatest around the shoreline of the estuary, and decreased over summer due to cannibalism and molting into higher instar classes. Adult crabs (instar 18+) dominate crab biomass (g/m^2). Adult crabs were initially patchily distributed across the entire estuary, but once dynamic hypoxic patches formed, these patches “chased” the crabs around the estuary.