Successes of Restoration and Its Effect on the Fish Community in a Freshwater Tidal Embayment of the Potomac River, USA

Abstract

After a local pollution control plant significantly reduced phosphorus loading into a phytoplankton-dominated tributary of the Potomac River in the early 1980's, water quality and biological communities were monitored bi-weekly from April-September. After a 10-year time-lag, submerged aquatic vegetation (SAV), once abundant in this freshwater tidal embayment, returned to the area in 1993. After additional reductions in nitrogen load starting in 2000, the system completely switched to a SAV-dominated state in 2005. Fish abundance didn't change during these distinct phase changes, but the fish community structure did. Increases in SAV provided refuge and additional spawning substrate for species with adhesive eggs such as Banded Killifish (Fundulus diaphanus), which is now the most abundant species in the embayment. Other changes seen were a decrease in the relative contribution of open water dwelling species such as White Perch (Morone americana), and an increase of visual predators such as Largemouth Bass (Micropterus salmoides). The 30-year record of data from this Potomac River tributary has revealed many important long-term trends that validate the effectiveness of initiatives to improve water treatment, and will aid in the continued management of the watershed and point source inputs.

The First International Snakehead Symposium: News from the Front(s)

“…Food habitats of C. argus in Virginia rivers and reservoirs consisted disproportionally of Bluegill Lepomis macrochirus by weight, while Northern Snakehead in rivers consumed Banded Killifish Fundulus diaphanous more frequently than other items (Isel and Odenkirk, in press). Despite increased predatory pressure, de Mutsert et al (2017) found Banded Killifish abundance in Pohick Bay, one of the first Potomac River sites colonized, had increased since Northern Snakehead arrived. Despite increased predatory pressure, de Mutsert et al (2017) found Banded Killifish abundance in Pohick Bay, one of the first Potomac River sites colonized, had increased since Northern Snakehead arrived.…”

“…These findings were similar to those of Saylor et al (2012) and implied that Northern Snakehead were opportunistic feeders consuming food items most commonly encountered in their habitats. Despite increased predatory pressure, de Mutsert et al (2017) found Banded Killifish abundance in Pohick Bay, one of the first Potomac River sites colonized, had increased since Northern Snakehead arrived. Lapointe et al (in press) further determined Northern Snakehead exhibited diurnal feeding and movement behavior and were most likely to feed after sunrise on outgoing tides.…”

Optimized suspect screening approach for a comprehensive assessment of the impact of best management practices in reducing micropollutants transport in the Potomac River watershed

“…In this regard, ambient water quality criteria was developed to reduce nutrient and sediment-based pollution entering the bay ( USEPA 2003 ). Implementation of strategies to decrease point-source nutrient loading resulted to a recovery from eutrophication, and a shift of the tidal embayment from phytoplankton - submerged to submerged aquatic vegetation was observed ( de Mutsert et al., 2017 ; Jones, 2020 ).…”