Aquatic Food Webs

Aquatic Food Webs [Image: US EPA]
Aquatic Food Webs [Image: US EPA]

Aquatic food webs are conceptual diagrams that demonstrate the flow of energy and nutrients in aquatic systems. Although the species that make up aquatic food webs will greatly vary depending on habitat type, the basic trophic levels or feeding levels of food webs are similar. Producers such as phytoplankton, aquatic plants, and algae use photosynthesis to convert sunlight and nutrients into living tissue. Primary consumers such as zooplankton and plant grazers eat producers. Secondary and tertiary consumers such as invertebrate predators, birds, fish, mammals, and humans eat lower-level prey items. Decomposers consume dead plants and animals, breaking organic matter down into nutrients. Since organisms seldom feed exclusively on another, several food chains are often woven together to form a "food web," a complex cycle of interconnected organisms and organic matter.

Explore the NBII Fisheries and Aquatic Resources Node's Aquatic Organisms section for more information about the wide variety of organisms that use the aquatic environment, ranging from endangered species to aquaculture.

Discover the NBII Bird Conservation Node's U.S. Fish and Wildlife Service Focal Bird Species, many of which are shorebirds, seabirds, and waterfowl that are important components of aquatic food webs.

Featured Citizen Science

[Image: World Water Monitoring Day]
[Image: World Water Monitoring Day]

World Water Monitoring Day is an international water monitoring program that builds public interest in protecting water resources through citizen science. A standard, easy-to-use water quality test kit is available through the website and includes testing materials for temperature, pH, turbidity, and dissolved oxygen. Worldwide monitoring results, stories, and photos are shared through the WWMD website database.

FishBase

FishBase

Fishbase is a searchable global database of fish species information.

FishBase on the web contains practically all fish species known to science. Search over 28,000 fish species by common name, scientific name, ecosystem, or country. Or, use the search feature to find tools, maps, or references.

Learn more about FishBase.

Rivers

Beckler River in Yellowstone National Park
[Photo: Patrick Rogers]

Rivers contain less than 0.01% of the Earth's water budget, yet they are vital resources for all organisms that depend on fresh water. They are fed by groundwater springs or by surface water runoff (overland flow) in a watershed. A watershed is defined as the total land area that drains surface water to a single point. A river's discharge, measured as the volume of water flowing past a given point during a given period of time (typically in units of cubic feet or meters per second), reflects the amount of water in the river. Discharge can range from a few cfs in a small mountain stream to over 12 million cfs in the Mississippi River at New Orleans, and can vary according to a number of factors. The highest recorded river flow in the world is 52.5 million cfs, measured in the Amazon River in Brazil.

Chemical processes in running water are different than in standing water. Running water is typically higher in dissolved oxygen, because oxygen can diffuse into the water through turbulent flow. It also has a chemical and mineral content influenced by the its substrate, because rocks are weathered by the erosive forces of running water. Nutrient spiraling is also an important aspect of chemical processes in running water: as nutrients travel in a downstream direction, they are used by living organisms and then released again as waste or through decay.


Sources:
Cech, T. 2005. Principles of Water Resources, Second Edition. John Wiley and Sons. Hoboken, NJ.
Moss, B. 1998. Ecology of Freshwaters, Third Edition. Blackwell Science. Malden, MA.

To find out more about rivers including their classification, habitats, and human impacts, follow the links below:

Futaleufu River [Photo: Patrick Rogers] Classification
Learn about how rivers are classified.
Potomac River eutrophication [Photo:NOAA]Human Impacts (Accessible soon)
Find out about how human activities can affect river habitats.
Kalamazoo River [Photo: EPA]River Habitats
Learn about the types of habitats within rivers.


Discover the National Fish Habitat Action Plan and Data

NFHAP logo [Image: National Fish Habitat Action Plan]
[Image: National Fish Habitat Action Plan]

The National Fish Habitat Action Plan (NFHAP) is an unprecedented attempt to address a nationwide fish crisis by focusing on the loss and degradation of their habitat. The Plan was born in 2001 by an ad hoc group supported by the Sport Fishing and Boating Partnership Council. This group was inspired to develop a partnership effort for fish conservation in the image of the successful and strategic North American Waterfowl Management Plan.

As a federal-level partner, the USGS-NBII was designated by the National Fish Habitat Board to house the data delivery system supporting the National Fish Habitat Action Plan. Find out more about NBII's role in the NFHAP and the data associated with the Plan.

National Wild & Scenic Rivers

[Image: National Wild and Scenic Rivers System]
[Image: National Wild and Scenic Rivers System]

The National Wild and Scenic Rivers System was created in 1968 "to preserve certain rivers with outstanding natural, cultural, and recreational values in a free-flowing condition for the enjoyment of present and future generations." Designated rivers are classified as wild, scenic, or recreational, and are managed by federal or state agencies with the goal of protecting and enhancing the values that caused it to be designated.

Nutrient Cycling vs. Spiraling

Nitrogen and phosphorus are important to aquatic ecosystems in their dissolved or available form for organisms to incorporate into living tissue, and influence the overall productivity of a given ecosystem. They are taken up by living organisms and move through the aquatic food web, including release as waste products and decomposition, in a pattern referred to as the nutrient cycle . In relatively closed systems such as lakes and reservoirs, available nutrients are often cycled repeatedly before they are exported. However, in rivers, the effect of running water transforms the nutrient cycle into a nutrient spiral , in which nutrients are transported downstream in addition to moving through aquatic food webs. "Tighter" nutrient spirals refer to stream systems that retain nutrients relatively well, through instream habitat features that slow the downstream loss of nutrients.

Highlight - The Cosumnes River

Cosumnes River in flood
CRG Image Library - Joshua H. Viers

The Cosumnes River is the last undammed river draining the western side of the Sierra Nevada, its waters flowing into the Bay-Delta southeast of Sacramento. Because it is a free-flowing river, it has provided a laboratory for studying the ecological properties of a natural hydrological regime. The University of California, Davis, in collaboration with seven agency and non-profit groups, undertook an eight-year study in the Cosumnes River Watershed to learn more about watershed conservation and restoration. The results of this study are presented at the site of the Cosumnes Research Group.

The Clean Water Act

EPA logo [Image: U.S. Environmental Protection Agency]
EPA logo [Image: U.S. Environmental Protection Agency]

"The objective of the Federal Water Pollution Control Act, commonly referred to as the Clean Water Act (CWA), is to restore and maintain the chemical, physical, and biological integrity of the nation's waters by preventing point and nonpoint pollution sources, providing assistance to publicly owned treatment works for the improvement of wastewater treatment, and maintaining the integrity of wetlands." Visit the US EPA Clean Water Act website for detailed information about the Clean Water Act, including Total Maximum Daily Loads (TMDLs), point and non-point source pollution measures, wetlands regulations, estuary regulations, and more.

USGS Aquatic GAP Program

GAP Logo
[Copyright: USGS GAP Analysis Program]

The goal of the GAP Analysis Program is to keep common species common by identifying those species and plant communities that are not adequately represented in existing conservation lands. Common species are those not currently threatened with extinction. By identifying their habitats, GAP Analysis gives land managers and policy makers the information they need to make better-informed decisions when identifying priority areas for conservation.

Regional Projects:

Resources:

The NBII Program is administered by the Biological Informatics Program of the U.S. Geological Survey
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