Bioassessment of fish communities of the upper Delaware River

E. van Snik Gray; R. M. Ross; R. M. Bennett

Home/Archive/USGS

USGS · 70029289

Bioassessment of fish communities of the upper Delaware River

E. van Snik Gray·R. M. Ross·R. M. Bennett

View original source ↗Export metadata ↓

Abstract

We assessed the biotic integrity of the middle-to-upper Delaware River. We sampled fish and assembled water quality data for eight stations and three habitat types (pool, riffle, and submerged aquatic vegetation [SAV]) of the Delaware River and applied an existing index of biotic integrity (IBI) recently developed for the northern mid-Atlantic slope drainages. We used Spearman's correlation to test IBI scores against measures of water quality (WQI) and cultural pollution. IBI scores were not significantly correlated with WQI, but were significantly negatively correlated with sewage load of adjacent tributaries (rs = -0.647, p = 0.08). Sites ranged from good to fair in biotic integrity. Fish assemblage composition from all three habitat types was necessary in order to accurately characterize biotic integrity. Of the three habitat types, fish assemblages from SAV habitats had the greatest positive effect on biotic integrity. Continued application of the IBI may be useful as a long-term monitoring tool as this river corridor becomes increasingly urbanized.

Explore related subjects

Northeastern Naturalist Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

E. van Snik Gray, R. M. Ross, R. M. Bennett. 2005. Bioassessment of fish communities of the upper Delaware River. https://pubs.usgs.gov/publication/70029289

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Relative activity of three bat species Impacted by white-nose syndrome on the Chesapeake and Ohio Canal National Historical Park

White-nose syndrome, a disease caused by the fungal-pathogen Pseudogymnoascus destructans , has caused drastic reductions in populations of several North American hibernating species of bats including Myotis lucifugus (Little Brown Bat), Myotis septentrionalis (Northern Long-eared Bat), and Perimyotis subflavus (Tricolored Bat). Recent data indicate that populations of Little Brown Bats may be stabilizing and/or increasing in the northeastern region of the US, while others, such as Northern Long-eared Bats, continue to decline. Whether these trends extend to the mid-Atlantic region is currently unknown. To better understand population changes over time, habitat associations, and species dynamics, we developed models of relative activity from bat acoustic data collected on the National Park Service's Chesapeake and Ohio Canal National Historical Park along the Potomac River Corridor in western Maryland between 2016 and 2022. Consistent with pre-disease habitat associations, Little Brown Bats and Tricolored Bats exhibited a positive correlation with proximity to water bodies. Notably, we found Little Brown Bat and Tricolored Bat populations potentially were increasing, whereas Northern Long-eared Bats showed no correlation with examined habitat covariates and had low detection levels, trends consistent with broader declines throughout their range.

Maryland↗

USGS2025

Common Terns (Sterna hirundo) use of a staging site in the Chesapeake Bay

In 2021, we initiated fieldwork to assess the relative importance of a staging area for Sterna hirundo (Common Tern) at a pier at the confluence of the Patuxent River and Chesapeake Bay, MD. During the post-breeding periods of 2021 through 2023, we resighted 378 banded Common Terns at this staging area, with individuals originating from 6 breeding colonies. Most banded individuals were from Poplar Island, a major nesting site 50 km north of the pier, with up to 37% of that island's annual hatch-year population observed at this staging area. Additionally, biologists have previously observed staging terns at this site, suggesting these observations do not reflect a change in the species' behavior within the region. Cumulatively, our data suggest that this habitat acts as an important staging area for the Chesapeake Bay's Common Tern population, particularly for those nesting on Poplar Island.

Maryland↗

USGS2025

Observation of unusual neonate-clustering behavior on maternal Cambarus chasmodactylus (New River Crayfish) after molting

Cambarus chasmodactylus (New River Crayfish) is one of the largest crayfish species occurring in the Appalachian Mountains and occupies a niche similar to several highly imperiled crayfishes within the same region. While conducting a controlled mesocosm study assessing the impacts of contaminants on crayfish growth, development, and reproductive status, we recorded an observation where New River Crayfish neonates clustered around the head of an untreated, reference maternal crayfish after molting. This neonate head-clustering behavior did not appear to impact the female during the 3-week period the behavior was observed. Further observations are needed to determine if this behavior occurs across other crayfish species, and if it is displayed outside of captive conditions.

West Virginia↗