Temporal variation in upper bay mesohaline benthic communities: I. The 9-m mud habitat

Yearly and seasonal changes in the structure of the macrobenthic (>1.0 mm) community occurring in the 9-m mud habitat of the Calvert Cliffs region of the Chesapeake Bay were examined for three years. Seasonal changes in the numerically dominant species resulted in varying community structure and was characterized by a near total faunal depletion during summer, initial recolonization during early fall, secondary recolonization during late fall, and growth and structural development during winter and spring. The faunal depletion that occurred each summer caused the cycle to repeat on an annual basis. The structure of the community was similar each year during initial recolonization (fall), but varied during secondary recolonization (winter and spring), reflecting the recruitment success of species that reproduce in the fall (i.e.,Macoma balthica, Mulinia lateralis, Nereis succinea, andParaprionospio pinnata). These findings have profound implications for the design and interpretation of power plant preoperational-postoperational impact studies.