Environmental Stressors and Thresholds

USGS is working with federal, state and local partners to develop multiple assessments of stream and river conditions in non-tidal areas of the Chesapeake Bay watershed. These assessments will help managers preserve stream health and improve biological conditions in impaired streams as the human population and climate continue to change in this region.

USGS is helping with the design of a population survey and developing mathematical models to assess potential activities to manage the population of invasive blue catfish ( Ictalurus furcatus ) in the Chesapeake Bay. This research will help managers determine the cost and feasibility of approaches to control this invasive species.

USGS is collaborating with many biologists in analysis of data on osprey ( Pandion haliaetus ) and their prey (menhaden, Brevoortia tyrannus , and other species of fish) in the middle and lower Chesapeake Bay and its tributaries. The data compiled and collected will help determine if a lack of menhaden or other environmental factors are affecting osprey reproductive success in portions of the...

Stream ecosystems support vital resources that may be jeopardized by climate change and climate stressors such as drought.

There is a growing and urgent need to develop and implement innovative strategies to research, monitor, and manage freshwater resources as societal demands escalate simultaneously with climate-driven changes in water availability.

Collaboration between the world-class expertise of USGS scientists, the Atlantic States Marine Fisheries Commission’s Science Program, and state and federal fishery agencies demonstrates the power of partnerships to solve seemingly-insurmountable problems in sustainable and cooperative management of Atlantic coastal fisheries.

Streams and rivers provide habitat for a diverse array of aquatic and semi-aquatic species. However, human alteration to landscapes and riverscapes has affected this habitat resulting in its degradation and thus loss of habitat and associated sensitive aquatic species. While this relationship has been known for many years, only recently has the availability of data and analytical capabilities...

Widespread shale oil and gas (unconventional oil and gas, UOG) has only recently begun and many gaps in our knowledge of its potential effects to freshwaters exist.

Stream flow is a fundamental driver of ecological structure and function, but its influence on bioassessment measures is poorly understood. Although extreme flow conditions (e.g., floods and droughts) have long been known to play a central role in structuring stream communities, a mechanistic understanding of the linkages between flow variables, landscape and local physical characteristics, and...

American Shad are the most numerous and economically important anadromous species on the east coast of the United States. Yet in many river systems their populations have experienced declines, primarily due to the impacts of dams and habitat loss.