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Ecological monitoring sites Albemarle-Pamlico drainage basin

Completed
By South Atlantic Water Science Center (SAWSC) August 23, 2024

National Water Quality Assessment (NAWQA), Cycle 1 (1991-2000),  Albemarle-Pamlico study area (ALBE), location of ecological sampling sites.

From 1993 to 1995, over 800 biological samples were collected and analyzed as part of the ALBE study. Community-level investigations of fish, invertebrates, and periphyton provided an ecological assessment. The bed-sediment and tissue collection provided information about the occurrence and distribution of trace elements and organic contaminants in the study area. Habitat- and water-chemistry data also were collected to aid in the interpretation of environmental factors that affect aquatic communities.

Station name Station ID Aquatic communities
sampled		 Media sampled for
contaminants
[SR, Secondary Road; NA, not applicable; US, US Highway; NC, NC Highway; Rt, Rural Route]
Ahoskie Creek near Poortown, NC 02053490 invertebrates, fish tissue, bed sediment
Albemarle Canal near Swindell, NC 02084558 fish, algae bed sediment
Aycock Swamp at SR 1629 near Stantonsburg, NC 0209062000 algae NA
Bear Creek at Mays Store, NC 0208925200 invertebrates, fish, algae tissue
Beaverdam Creek at SR 1006 near Grantham, NC 0208831815 invertebrates, fish NA
Black Creek at Black Creek, NC 0209058180 algae NA
Blackwater River near Franklin, VA 02049500 fish tissue, bed sediment
Bloomery Swamp near Wilson on NC 42, NC 0209047200 algae NA
Chicod Creek at SR 1760 near Simpson, NC 02084160 invertebrates, fish, algae tissue, bed sediment
Contentnea Creek at Grifton, NC 0209176400 algae NA
Contentnea Creek at Hookerton, NC 02091500 invertebrates, fish, algae tissue, bed sediment
Contentnea Creek at NC 222 at Stantonsburg, NC 02090629 algae NA
Contentnea Creek at SR 1222 near Herrings Crossroads, NC 0209110000 algae NA
Contentnea Creek near Evansdale, NC 02090519 algae NA
Contentnea Creek near Lucama, NC 02090380 algae NA
Contentnea Creek near Wilson, NC 02090500 algae NA
Crabtree Creek at US 1 at Raleigh, NC 02087324 NA tissue, bed sediment
Cutawhiskie Creek at SR 1141 at St John, NC 0205317300 invertebrates, fish NA
Cypress Swamp at Cypress Chapel, VA 02043500 invertebrates NA
Cypress Swamp at SR 31 near Dendron, VA 02047480 invertebrates NA
Devils Cradle Creek at SR 1412 near Alert, NC 02082731 invertebrates, fish, algae tissue, bed sediment
Duke Swamp near Sunbury, NC 02053580 invertebrates NA
Durham Creek at Edward, NC 02084540 invertebrates, fish, algae bed sediment
Ellerbe Creek near Gorman, NC 02086849 NA bed sediment
Ethridge Swamp at Oak City, NC 0208104942 invertebrates NA
Goodwin Mill Creek at SR 1111 near Belvidere, 0204388850 invertebrates NA
Great Swamp near Black Creek, NC 0209059000 invertebrates, algae NA
Grindle Creek near Staten at SR 1425, NC 0208412479 invertebrates NA
Holston Creek at NC 58 near Morton Fork, NC 0209273300 invertebrates, fish NA
Hominy Swamp at SR 1606 near Evansdale, NC 0209051600 algae NA
Kendrick Creek at SR 1125 near Roper, NC 0208114385 invertebrates, fish NA
Knobbs Creek at SR 1332 near Elizabeth City, 0204386000 invertebrates NA
Maple Swamp at NC 97 near Legget, NC 0208331123 invertebrates, fish NA
Mill Creek at Overshot, NC 02088136 invertebrates, fish NA
Mill Creek at Rt 684 near Sunbeam, VA 02047360 invertebrates NA
Moccasin Creek near Heflin, NC 0209010900 algae NA
Nahunta Swamp at SR 1537 near Fremont, NC 0209096110 invertebrates, fish, algae NA
Nahunta Swamp near Shine, NC 02091000 algae NA
Neuse River at Kinston, NC 02089500 fish tissue, bed sediment
Neuse River near Cox Mill, NC 02088119 NA tissue, bed sediment
Newland Canal near Acorn Hill, NC 0204378000 invertebrates NA
Newland Canal near Lynchs Corner, NC 02043814 invertebrates NA
North Flat River at Timberlake, NC 02085390 NA tissue, bed sediment
North Meherrin River near Lunenburg, VA 02051000 NA tissue, bed sediment
Northwest Fork Alligator River above SR 94, NC 0208117804 invertebrates NA
Nottoway River near Sebrell, VA 02047000 fish tissue, bed sediment
Pete Mitchell Swamp at SR 1409 near Penny Hil 02083833 invertebrates, fish, algae tissue, bed sediment
Potecasi Creek below SR 1504 at Creeksville, 0205310895 invertebrates NA
Roanoke River at Roanoke Rapids, NC 02080500 NA tissu
Scuppernong River at SR 1142 at Creswell, NC 0208116550 invertebrates NA
Swift Creek at Hilliardston, NC 02082770 NA tissue, bed sediment
Swift Creek near Apex, NC 02087580 NA tissue, bed sediment
Tar River at Tarboro, NC 02083500 fish tissue, bed sediment
Tar River near Tar River, NC 02081500 NA tissue, bed sediment
The Slough near Saulston, NC 02090980 algae NA
Thoroughfare Swamp near Dobbersville, NC 0208828500 invertebrates, fish NA
Toisnot Swamp at US 264 near Wilson, NC 0209075800 algae NA
Trent River near Trenton, NC 02092500 NA tissue, bed sediment
Tuckahoe Creek near Pleasant Hill, NC 0209239000 invertebrates, fish NA
Turkey Creek at SR 1101 near Bailey, NC 0209028880 algae NA
Tyson Creek near Falkland, NC 02083891 invertebrates, fish NA
Van Swamp near Hoke, NC 02084557 invertebrates, fish, algae bed sediment

 

The objectives of the ecological assessment were:

  1. To describe macroinvertebrate, fish, and periphyton community structure at ALBE fixed sites using sampling techniques that permit comparisons among sites.
  2. To compare macroinvertebrate, fish, and periphyton community structure among ALBE sites.
  3. To explore relations among macroinvertebrate, fish, and periphyton community structure and environmental conditions, including water chemistry, physical habitat, and land use.
  4. To evaluate whether the ALBE fixed sites are representative by comparing macroinvertebrate community structure and environmental conditions at ALBE sites to other small Coastal Plain streams in the Study Unit.
  5. To explore the relative utility of winter versus spring macroinvertebrate sampling for water-quality assessments of small Coastal Plain streams using the NAWQA sampling protocols.
  6. To explore within-site variability of macroinvertebrate, fish, and periphyton community structure at selected streams in the Coastal Plain.

The objectives of the bed-sediment and tissue collection were:

  1. To characterize the occurrence of potential trace-element and hydrophobic organic contaminants in bed sediments and organism tissues at ALBE fixed sites.
  2. To investigate the occurrence of potential trace-element and hydrophobic organic contaminants in bed sediments and organism tissues at other selected sites, particularly in small Coastal Plain streams.

For the ecological assessment, data for the first two objectives were obtained by collecting at least one sample from each of the ALBE NAWQA indicator and integrator fixed sites (see Site Type description in Cycle I Surface-Water Study Design). Data for the third, fourth, and fifth objectives were obtained through a series of fish, invertebrate, and algal synoptic surveys. These surveys were designed to collect samples from as many sites as possible across a gradient of environmental conditions in the Coastal Plain physiographic province. Finally, data needed to meet the sixth objective were obtained by sampling (1) three different streams (multiple-reach sampling) at selected indicator fixed sites, and (2) fish communities from nine, 50-meter contiguous stream segments at two indicator synoptic sites (extended-reach sampling).

For information about the bed-sediment sampling and analysis, see Woodside and Simerl (1995). For the tissue component, Asiatic clams (Corbicula fluminea) and redbreast sunfish (Lepomis auritus) were collected and analyzed. Whole fish and clam soft tissues were analyzed for organic compounds; fish livers and clam soft tissues were analyzed for trace elements. For more information see Smith and Ruhl (1996) and Ruhl and Smith (1996).

Methods Publications

Biological data were collected according to nationally consistent methods.

The Role of Ecology in NAWQA

The ecological components of NAWQA consist of ecological surveys (characterizations of fish, benthic invertebrate, and algal communities) and tissue contaminant studies. Biological components are important to an integrated assessment of water quality because of factors such as (1) a wide variety of natural and human environmental influences (for example, chemical constituents, hydrologic modifications, sedimentation, and thermal changes); (2) bioconcentration of certain contaminants; (3) exposure to environmental influences over multiple temporal and spatial scales (for example, algae integrate environmental exposure over several millimeters for periods of several weeks, whereas fish may integrate environmental exposure over many kilometers for a decade or more); and (4) public interest and concern, particularly for endangered species.

Ecological surveys as part of NAWQA are designed to characterize fish, benthic invertebrate, and algal communities and associated instream and riparian habitats. Community analysis offers several advantages for large-scale water-quality assessments when compared with toxicity testing, biochemical characterization, or direct measurement of ecological processes. For example, community surveys directly relate to actual ambient conditions, take into account a large range of species representing a variety of environmental exposure pathways, eliminate the need to culture and maintain test organisms, and incorporate secondary effects that arise from the interactions of populations through competitive and predator-prey interactions. Community surveys remain the only means of directly assessing the biological integrity of a site and the only approach that is sensitive to toxicological influences and habitat degradation resulting from changes in land use.

Fish Communities

A fish community is a group of fishes belonging to a number of different species that occur in the same area and interact with each other. The structure of a fish community is determined by the species present, their relative abundances, life-stages and size distributions, and their distributions in space and time. Changes in fish community structure occur with natural or human changes in the physical and chemical characteristics of their environment. The ability to detect changes in fish community structure can be gained by developing an increased understanding of the factors that determine the distribution and abundance of fish species and identifying relations among patterns in fish community structure, physical habitat, and water chemistry conditions.

The study of fish communities is an essential component of many water-quality assessment programs because fish are particularly sensitive indicators of water-quality conditions. Human influences, such as changes in water chemistry or physical habitat modifications, can alter fish communities by disrupting their structures. Changes in fish community structure can be detected through changes in size components of the community, functional groups, species diversity, and relative abundance.

Benthic Invertebrates

Benthic invertebrates (insects, mollusks, crustaceans, and worms) are important elements of ecological surveys because they tend to (1) live in, on, or near streambed sediments; (2) have, with the exception of most mollusks, life cycles (months to a few years) that are intermediate to fish (years to decades) and algae (days to weeks); and (3) be relatively sessile compared to larger organisms, such as fish. This combination of characteristics ensures the uniqueness of benthic invertebrates to (1) respond to natural and anthropogenic environmental conditions that physically or chemically alter streambed sediments (for example, sedimentation, xenobiotics, eutrophication, or hydrologic modifications), (2) integrate effects over a relatively short (annual) time period, and (3) characterize effects over a relatively small spatial area in contrast to fish, which may travel over long distances. These factors make benthic invertebrates well suited for use in assessing site-specific water quality and comparing spatial patterns of water quality at multiple sites, and for integrating effects that represent 6 months to a year of exposure at a site. Benthic invertebrates also are particularly useful in monitoring cumulative effects at a site resulting from conditions upstream. Consequently, these organisms are used increasingly by State and Federal agencies as a cost-effective method of assessing water-quality conditions in a regulatory context.

Algal Communities

The algal component of NAWQA ecological surveys is designed primarily to characterize the species distribution and community structure of benthic algae (periphyton) and their relation to water quality. Estimates of algal biomass (for example, ash-free dry mass and chlorophyll content) are optional and may be made in some NAWQA Study Units. The collection of phytoplankton samples (or the use of artificial substrates for collecting periphyton samples) may be considered for large, nonwadeable streams and rivers. Stream locations are chosen to represent major natural and human factors that are thought to significantly influence the quality of water.

Periphyton samples for NAWQA ecological surveys typically are collected in conjunction with the sampling of benthic invertebrates described by Cuffney and others (1993). Periphyton microhabitats are submerged surfaces in streams and rivers, such as rocks, logs, plants, sand, and silt, that support the attachment and growth of algae. Qualitative periphyton samples are intended to provide a list of species (taxa richness) present in the sampling reach. Samples of algae are collected from each periphyton microhabitat present in the sampling reach and composited into one sample. Quantitative periphyton samples are collected to measure the relative abundance and density (algal cells per square centimeter) of each taxon present in each of two contrasting instream habitat types in a sampling reach. Quantitative samples are collected using a variety of sampling devices; the appropriate choice of sampling equipment is dictated by the character of the dominant periphyton growth forms and microhabitats in the sampling reach.

Physical Habitat

Habitat includes all factors that define the stream environment and its relation to aquatic organisms. Physical habitat (for example, the type of streambed material) is characterized to describe environmental settings at sites selected for water-quality assessment. Habitat characterization also provides the opportunity to examine the relative influence of changes in physical and chemical characteristics on biological communities to better interpret long-term changes in water-quality conditions.

Habitat sampling is based on a tiered design that incorporates information at basin, stream-segment, and stream-reach levels. Basin-level habitat data are obtained from geographic information system (GIS) databases and include information on hydrology, climate, land use, geology, and soils. Stream-segment data are obtained from GIS databases and topographic maps. A stream segment is defined as that part of the stream bounded by tributary junctions or major discontinuities, such as waterfalls, landform features, significant changes in gradient, or point-source discharges. Segment-level habitat data include information on stream meandering, gradient, elevation, and water-management features, such as dams, bridges, canals, or diversions. The stream reach is a part of the stream where stream, bank, and flood-plain habitat features are representative of the local area, close to the location where chemical data are collected from the water column and streambed sediment. Stream-reach characterizations include information on factors such as streamflow and bank stability.

In addition to the collection of data on physical factors, biological data on instream and bank vegetation are collected at the stream reach. Instream and bank vegetation provide a critical link between aquatic and terrestrial factors that influence water quality. Transects are established perpendicular to the stream, and in-stream and bank vegetation species, density, and species dominance are noted along each transect.

Tissues

Determination of contaminant concentrations in biological tissues is widely used as a method of monitoring and assessing contaminant distributions and bioavailability in space and time. Phillips (1980) has identified three benefits of employing tissue analysis: (1) Concentrations of contaminants may be greater in tissues than in water because of bioconcentration, bioaccumulation, or biomagnification. Therefore, tissue analysis increases the probability of detecting trace amounts of some contaminants in the environment. (2) Measurements of contaminant concentrations in organisms provide a time-averaged assessment of the contaminant in question. (3) Concentrations of contaminants in tissues provide direct measurement of bioavailability of toxicants that accumulate in biological tissues. Direct determination of bioavailability is especially important because the effects of contaminants on biota are not necessarily a simple function of their total concentrations in water and sediments. A fourth benefit not mentioned by Philllips is that, where they are used together, tissue, water, and sediment analysis provide complementary lines of evidence in understanding the complexities of contaminant fate, distribution, and effects.

An important product of tissue analysis in NAWQA is data that are comparable at local, regional, and national scales. Resident taxa are collected for the NAWQA tissue bioassessment. In order to assure the analyses of taxa that are comparable over the broadest areas possible, a NAtional Target Taxa (NATT) list defines the taxa that local teams target in most collection efforts. The choices from the NATT list to be analyzed at each site depend on occurrence and abundance of resident taxa, whether the sample will be analyzed for organics or trace elements, the objective to be satisified, the ability to obtain adequate mass for analysis, and whether samples of comparable taxa are being collected elsewhere in the basin (or in the Nation). The local study team makes specific choices within the national guidelines. Although the details of the NATT list may change as experience increases, it provides a national tissue-contaminant data base for selected species widespread in freshwater environments.

These descriptions of the biological components of the NAWQA program are from Crawford and Luoma (1993), Cuffney and others (1993), Meador and others (1993), Meador and Gurtz (1994), Phillips (1980), and Porter and others (1993).

 

Release Date: 11/03/2020

National Water Quality Assessment (NAWQA), Cycle 1 (1991-2000),  Albemarle-Pamlico study area (ALBE), location of ecological sampling sites.

From 1993 to 1995, over 800 biological samples were collected and analyzed as part of the ALBE study. Community-level investigations of fish, invertebrates, and periphyton provided an ecological assessment. The bed-sediment and tissue collection provided information about the occurrence and distribution of trace elements and organic contaminants in the study area. Habitat- and water-chemistry data also were collected to aid in the interpretation of environmental factors that affect aquatic communities.

Station name Station ID Aquatic communities
sampled		 Media sampled for
contaminants
[SR, Secondary Road; NA, not applicable; US, US Highway; NC, NC Highway; Rt, Rural Route]
Ahoskie Creek near Poortown, NC 02053490 invertebrates, fish tissue, bed sediment
Albemarle Canal near Swindell, NC 02084558 fish, algae bed sediment
Aycock Swamp at SR 1629 near Stantonsburg, NC 0209062000 algae NA
Bear Creek at Mays Store, NC 0208925200 invertebrates, fish, algae tissue
Beaverdam Creek at SR 1006 near Grantham, NC 0208831815 invertebrates, fish NA
Black Creek at Black Creek, NC 0209058180 algae NA
Blackwater River near Franklin, VA 02049500 fish tissue, bed sediment
Bloomery Swamp near Wilson on NC 42, NC 0209047200 algae NA
Chicod Creek at SR 1760 near Simpson, NC 02084160 invertebrates, fish, algae tissue, bed sediment
Contentnea Creek at Grifton, NC 0209176400 algae NA
Contentnea Creek at Hookerton, NC 02091500 invertebrates, fish, algae tissue, bed sediment
Contentnea Creek at NC 222 at Stantonsburg, NC 02090629 algae NA
Contentnea Creek at SR 1222 near Herrings Crossroads, NC 0209110000 algae NA
Contentnea Creek near Evansdale, NC 02090519 algae NA
Contentnea Creek near Lucama, NC 02090380 algae NA
Contentnea Creek near Wilson, NC 02090500 algae NA
Crabtree Creek at US 1 at Raleigh, NC 02087324 NA tissue, bed sediment
Cutawhiskie Creek at SR 1141 at St John, NC 0205317300 invertebrates, fish NA
Cypress Swamp at Cypress Chapel, VA 02043500 invertebrates NA
Cypress Swamp at SR 31 near Dendron, VA 02047480 invertebrates NA
Devils Cradle Creek at SR 1412 near Alert, NC 02082731 invertebrates, fish, algae tissue, bed sediment
Duke Swamp near Sunbury, NC 02053580 invertebrates NA
Durham Creek at Edward, NC 02084540 invertebrates, fish, algae bed sediment
Ellerbe Creek near Gorman, NC 02086849 NA bed sediment
Ethridge Swamp at Oak City, NC 0208104942 invertebrates NA
Goodwin Mill Creek at SR 1111 near Belvidere, 0204388850 invertebrates NA
Great Swamp near Black Creek, NC 0209059000 invertebrates, algae NA
Grindle Creek near Staten at SR 1425, NC 0208412479 invertebrates NA
Holston Creek at NC 58 near Morton Fork, NC 0209273300 invertebrates, fish NA
Hominy Swamp at SR 1606 near Evansdale, NC 0209051600 algae NA
Kendrick Creek at SR 1125 near Roper, NC 0208114385 invertebrates, fish NA
Knobbs Creek at SR 1332 near Elizabeth City, 0204386000 invertebrates NA
Maple Swamp at NC 97 near Legget, NC 0208331123 invertebrates, fish NA
Mill Creek at Overshot, NC 02088136 invertebrates, fish NA
Mill Creek at Rt 684 near Sunbeam, VA 02047360 invertebrates NA
Moccasin Creek near Heflin, NC 0209010900 algae NA
Nahunta Swamp at SR 1537 near Fremont, NC 0209096110 invertebrates, fish, algae NA
Nahunta Swamp near Shine, NC 02091000 algae NA
Neuse River at Kinston, NC 02089500 fish tissue, bed sediment
Neuse River near Cox Mill, NC 02088119 NA tissue, bed sediment
Newland Canal near Acorn Hill, NC 0204378000 invertebrates NA
Newland Canal near Lynchs Corner, NC 02043814 invertebrates NA
North Flat River at Timberlake, NC 02085390 NA tissue, bed sediment
North Meherrin River near Lunenburg, VA 02051000 NA tissue, bed sediment
Northwest Fork Alligator River above SR 94, NC 0208117804 invertebrates NA
Nottoway River near Sebrell, VA 02047000 fish tissue, bed sediment
Pete Mitchell Swamp at SR 1409 near Penny Hil 02083833 invertebrates, fish, algae tissue, bed sediment
Potecasi Creek below SR 1504 at Creeksville, 0205310895 invertebrates NA
Roanoke River at Roanoke Rapids, NC 02080500 NA tissu
Scuppernong River at SR 1142 at Creswell, NC 0208116550 invertebrates NA
Swift Creek at Hilliardston, NC 02082770 NA tissue, bed sediment
Swift Creek near Apex, NC 02087580 NA tissue, bed sediment
Tar River at Tarboro, NC 02083500 fish tissue, bed sediment
Tar River near Tar River, NC 02081500 NA tissue, bed sediment
The Slough near Saulston, NC 02090980 algae NA
Thoroughfare Swamp near Dobbersville, NC 0208828500 invertebrates, fish NA
Toisnot Swamp at US 264 near Wilson, NC 0209075800 algae NA
Trent River near Trenton, NC 02092500 NA tissue, bed sediment
Tuckahoe Creek near Pleasant Hill, NC 0209239000 invertebrates, fish NA
Turkey Creek at SR 1101 near Bailey, NC 0209028880 algae NA
Tyson Creek near Falkland, NC 02083891 invertebrates, fish NA
Van Swamp near Hoke, NC 02084557 invertebrates, fish, algae bed sediment

 

The objectives of the ecological assessment were:

  1. To describe macroinvertebrate, fish, and periphyton community structure at ALBE fixed sites using sampling techniques that permit comparisons among sites.
  2. To compare macroinvertebrate, fish, and periphyton community structure among ALBE sites.
  3. To explore relations among macroinvertebrate, fish, and periphyton community structure and environmental conditions, including water chemistry, physical habitat, and land use.
  4. To evaluate whether the ALBE fixed sites are representative by comparing macroinvertebrate community structure and environmental conditions at ALBE sites to other small Coastal Plain streams in the Study Unit.
  5. To explore the relative utility of winter versus spring macroinvertebrate sampling for water-quality assessments of small Coastal Plain streams using the NAWQA sampling protocols.
  6. To explore within-site variability of macroinvertebrate, fish, and periphyton community structure at selected streams in the Coastal Plain.

The objectives of the bed-sediment and tissue collection were:

  1. To characterize the occurrence of potential trace-element and hydrophobic organic contaminants in bed sediments and organism tissues at ALBE fixed sites.
  2. To investigate the occurrence of potential trace-element and hydrophobic organic contaminants in bed sediments and organism tissues at other selected sites, particularly in small Coastal Plain streams.

For the ecological assessment, data for the first two objectives were obtained by collecting at least one sample from each of the ALBE NAWQA indicator and integrator fixed sites (see Site Type description in Cycle I Surface-Water Study Design). Data for the third, fourth, and fifth objectives were obtained through a series of fish, invertebrate, and algal synoptic surveys. These surveys were designed to collect samples from as many sites as possible across a gradient of environmental conditions in the Coastal Plain physiographic province. Finally, data needed to meet the sixth objective were obtained by sampling (1) three different streams (multiple-reach sampling) at selected indicator fixed sites, and (2) fish communities from nine, 50-meter contiguous stream segments at two indicator synoptic sites (extended-reach sampling).

For information about the bed-sediment sampling and analysis, see Woodside and Simerl (1995). For the tissue component, Asiatic clams (Corbicula fluminea) and redbreast sunfish (Lepomis auritus) were collected and analyzed. Whole fish and clam soft tissues were analyzed for organic compounds; fish livers and clam soft tissues were analyzed for trace elements. For more information see Smith and Ruhl (1996) and Ruhl and Smith (1996).

Methods Publications

Biological data were collected according to nationally consistent methods.

The Role of Ecology in NAWQA

The ecological components of NAWQA consist of ecological surveys (characterizations of fish, benthic invertebrate, and algal communities) and tissue contaminant studies. Biological components are important to an integrated assessment of water quality because of factors such as (1) a wide variety of natural and human environmental influences (for example, chemical constituents, hydrologic modifications, sedimentation, and thermal changes); (2) bioconcentration of certain contaminants; (3) exposure to environmental influences over multiple temporal and spatial scales (for example, algae integrate environmental exposure over several millimeters for periods of several weeks, whereas fish may integrate environmental exposure over many kilometers for a decade or more); and (4) public interest and concern, particularly for endangered species.

Ecological surveys as part of NAWQA are designed to characterize fish, benthic invertebrate, and algal communities and associated instream and riparian habitats. Community analysis offers several advantages for large-scale water-quality assessments when compared with toxicity testing, biochemical characterization, or direct measurement of ecological processes. For example, community surveys directly relate to actual ambient conditions, take into account a large range of species representing a variety of environmental exposure pathways, eliminate the need to culture and maintain test organisms, and incorporate secondary effects that arise from the interactions of populations through competitive and predator-prey interactions. Community surveys remain the only means of directly assessing the biological integrity of a site and the only approach that is sensitive to toxicological influences and habitat degradation resulting from changes in land use.

Fish Communities

A fish community is a group of fishes belonging to a number of different species that occur in the same area and interact with each other. The structure of a fish community is determined by the species present, their relative abundances, life-stages and size distributions, and their distributions in space and time. Changes in fish community structure occur with natural or human changes in the physical and chemical characteristics of their environment. The ability to detect changes in fish community structure can be gained by developing an increased understanding of the factors that determine the distribution and abundance of fish species and identifying relations among patterns in fish community structure, physical habitat, and water chemistry conditions.

The study of fish communities is an essential component of many water-quality assessment programs because fish are particularly sensitive indicators of water-quality conditions. Human influences, such as changes in water chemistry or physical habitat modifications, can alter fish communities by disrupting their structures. Changes in fish community structure can be detected through changes in size components of the community, functional groups, species diversity, and relative abundance.

Benthic Invertebrates

Benthic invertebrates (insects, mollusks, crustaceans, and worms) are important elements of ecological surveys because they tend to (1) live in, on, or near streambed sediments; (2) have, with the exception of most mollusks, life cycles (months to a few years) that are intermediate to fish (years to decades) and algae (days to weeks); and (3) be relatively sessile compared to larger organisms, such as fish. This combination of characteristics ensures the uniqueness of benthic invertebrates to (1) respond to natural and anthropogenic environmental conditions that physically or chemically alter streambed sediments (for example, sedimentation, xenobiotics, eutrophication, or hydrologic modifications), (2) integrate effects over a relatively short (annual) time period, and (3) characterize effects over a relatively small spatial area in contrast to fish, which may travel over long distances. These factors make benthic invertebrates well suited for use in assessing site-specific water quality and comparing spatial patterns of water quality at multiple sites, and for integrating effects that represent 6 months to a year of exposure at a site. Benthic invertebrates also are particularly useful in monitoring cumulative effects at a site resulting from conditions upstream. Consequently, these organisms are used increasingly by State and Federal agencies as a cost-effective method of assessing water-quality conditions in a regulatory context.

Algal Communities

The algal component of NAWQA ecological surveys is designed primarily to characterize the species distribution and community structure of benthic algae (periphyton) and their relation to water quality. Estimates of algal biomass (for example, ash-free dry mass and chlorophyll content) are optional and may be made in some NAWQA Study Units. The collection of phytoplankton samples (or the use of artificial substrates for collecting periphyton samples) may be considered for large, nonwadeable streams and rivers. Stream locations are chosen to represent major natural and human factors that are thought to significantly influence the quality of water.

Periphyton samples for NAWQA ecological surveys typically are collected in conjunction with the sampling of benthic invertebrates described by Cuffney and others (1993). Periphyton microhabitats are submerged surfaces in streams and rivers, such as rocks, logs, plants, sand, and silt, that support the attachment and growth of algae. Qualitative periphyton samples are intended to provide a list of species (taxa richness) present in the sampling reach. Samples of algae are collected from each periphyton microhabitat present in the sampling reach and composited into one sample. Quantitative periphyton samples are collected to measure the relative abundance and density (algal cells per square centimeter) of each taxon present in each of two contrasting instream habitat types in a sampling reach. Quantitative samples are collected using a variety of sampling devices; the appropriate choice of sampling equipment is dictated by the character of the dominant periphyton growth forms and microhabitats in the sampling reach.

Physical Habitat

Habitat includes all factors that define the stream environment and its relation to aquatic organisms. Physical habitat (for example, the type of streambed material) is characterized to describe environmental settings at sites selected for water-quality assessment. Habitat characterization also provides the opportunity to examine the relative influence of changes in physical and chemical characteristics on biological communities to better interpret long-term changes in water-quality conditions.

Habitat sampling is based on a tiered design that incorporates information at basin, stream-segment, and stream-reach levels. Basin-level habitat data are obtained from geographic information system (GIS) databases and include information on hydrology, climate, land use, geology, and soils. Stream-segment data are obtained from GIS databases and topographic maps. A stream segment is defined as that part of the stream bounded by tributary junctions or major discontinuities, such as waterfalls, landform features, significant changes in gradient, or point-source discharges. Segment-level habitat data include information on stream meandering, gradient, elevation, and water-management features, such as dams, bridges, canals, or diversions. The stream reach is a part of the stream where stream, bank, and flood-plain habitat features are representative of the local area, close to the location where chemical data are collected from the water column and streambed sediment. Stream-reach characterizations include information on factors such as streamflow and bank stability.

In addition to the collection of data on physical factors, biological data on instream and bank vegetation are collected at the stream reach. Instream and bank vegetation provide a critical link between aquatic and terrestrial factors that influence water quality. Transects are established perpendicular to the stream, and in-stream and bank vegetation species, density, and species dominance are noted along each transect.

Tissues

Determination of contaminant concentrations in biological tissues is widely used as a method of monitoring and assessing contaminant distributions and bioavailability in space and time. Phillips (1980) has identified three benefits of employing tissue analysis: (1) Concentrations of contaminants may be greater in tissues than in water because of bioconcentration, bioaccumulation, or biomagnification. Therefore, tissue analysis increases the probability of detecting trace amounts of some contaminants in the environment. (2) Measurements of contaminant concentrations in organisms provide a time-averaged assessment of the contaminant in question. (3) Concentrations of contaminants in tissues provide direct measurement of bioavailability of toxicants that accumulate in biological tissues. Direct determination of bioavailability is especially important because the effects of contaminants on biota are not necessarily a simple function of their total concentrations in water and sediments. A fourth benefit not mentioned by Philllips is that, where they are used together, tissue, water, and sediment analysis provide complementary lines of evidence in understanding the complexities of contaminant fate, distribution, and effects.

An important product of tissue analysis in NAWQA is data that are comparable at local, regional, and national scales. Resident taxa are collected for the NAWQA tissue bioassessment. In order to assure the analyses of taxa that are comparable over the broadest areas possible, a NAtional Target Taxa (NATT) list defines the taxa that local teams target in most collection efforts. The choices from the NATT list to be analyzed at each site depend on occurrence and abundance of resident taxa, whether the sample will be analyzed for organics or trace elements, the objective to be satisified, the ability to obtain adequate mass for analysis, and whether samples of comparable taxa are being collected elsewhere in the basin (or in the Nation). The local study team makes specific choices within the national guidelines. Although the details of the NATT list may change as experience increases, it provides a national tissue-contaminant data base for selected species widespread in freshwater environments.

These descriptions of the biological components of the NAWQA program are from Crawford and Luoma (1993), Cuffney and others (1993), Meador and others (1993), Meador and Gurtz (1994), Phillips (1980), and Porter and others (1993).

 

Release Date: 11/03/2020

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