Ambient Macroinvertebrate Network (AMNET)

Benthic macroinvertebrate samples are collected using a 800 x 900 mesh D-net placed on the stream bottom. A sampler, standing upstream of the net, disturbs the stream bottom with their boot using the Kick method and collects the dislodged debris and macroinvertebrates that flow into the net. A riffle/run area is the ideal substrate in which to collect macroinvertebrates. It provides stable habitat in the form of large rocks and cobbles and is usually well oxygenated. Macroinvertebrate samples are also collected from Submerged Aquatic Vegetation (SAV) by sweeping the net through the SAV, combining the contents of the sample with the kick sample. Other areas such as root mats and undercut banks may also be sampled if present. In slower moving low gradient streams, riffle areas are usually not present, therefore, it will be necessary to sample with a multihabitat jab and sweep method. Contents of all samples in net are transferred to a sieve bucket and rinsed in stream water to remove fine sediment. The remaining sample is transferred to 1 liter, plastic collection bottles and preserved with formaldehyde for a 5-10 % final concentration. Samples are returned to the lab for sorting and identification.

NJDEP utilizes a multi-probe meter to measure Water Temperature, pH, Dissolved oxygen (DO), and Specific Conductivity. A sample is also collected for Turbidity testing using a portable turbidity meter. Nutrients samples are also collected and delivered to the NJ Department of Health for analysis.

The land surrounding the stream to be sampled can have an impact on the type of macroinvertebrates found at the site. A stream habitat assessment is performed at each site using the EPA Habitat assessment form for either a High gradient stream or Low gradient streams. Ten habitat parameters are assessed by the field staff to determine an overall Stream Habitat Assessment. Final score determines one of four habitat assessment ratings, namely: Optimal, Suboptimal, Marginal, or Poor. Other site observations are also recorded. This may offer a more complete picture as to the health of a stream.

Samples are returned to the NJDEP lab and macroinvertebrates are stored until chemically fixed (preserved). Once samples are completely fixed, samples are rinsed of excess formaldehyde and placed into a gridded tray. A grid is randomly selected using a random number table and all material within the grid is transferred to a Petri dish. The material in the dish is examined under low power (6.3x) using a stereo microscope. All organisms in a grid are collected and counted, and the process continues to the next randomly selected grid. This process continues until at least a 100 organism subsample is collected. Then each macroinvertebrate is identified using a Leica Model MZ6 stereo microscope capable of up to 40x magnification. A compound microscope with 100x, 200x, 400x, and 1000x magnification is used for very detailed identification. An extensive library of dichotomous keys reference documents is used to determine final identification down to the practicable taxonomic level. A full list of our dichotomous key documents can be found on the Reports page.

AMNET employs a multimetric index approach for assessment of biological condition, and regulatory thresholds for use attainment. Once all organisms have been identified, each taxa and count in a sample is entered into the Bureau’s Rapid Bioassessment Protocol (RBP Analysis) database. The RBP Analysis Program creates a random, 100 individual, subsample and calculates a bioassessment rating using the appropriate regional multi-metric index. New Jersey benthic macroinvertebrate communities can be statistically grouped into three distinct structures based on geographical regions: high gradient (above the Fall Line), low gradient (Coastal Plain excluding the Pinelands), and Pinelands. To accurately assess biological condition, an index was developed for each distinct region using guidelines outlined in USEPA's Rapid Bioassessment Protocols (RBP) for Use in Wadeable Streams and Rivers. The impairment indices assess sites from two perspectives: the condition of the macroinvertebrate community and the regulatory use attainment. An assessment framework was outlined to address both concerns, and a development report was prepared for each index: High Gradient Macroinvertebrate Index (HGMI), Coastal Plain Macroinvertebrate Index (CPMI), and the Pinelands Macroinvertebrate Index (PMI).

A summary of the index development and scoring criteria can be found in Appendix B of the AMNET SOP.

The objectives of the PWQBN are to:

1. establish a probabilistic network of sites to determine statewide estimates of biological impairment in a statistically sound manner; and
2. collect habitat and biological samples (macroinvertebrates) to link biological conditions to water quality at Ambient Surface Water Quality Monitoring Network (ASWQMN) probabilistic sites, where co-located

Data obtained will also be used by NJDEP in the generation of the biennial Integrated Water Quality Assessment Report (includes 305(b) report and 303(d) list). Sites were selected probabilistically using Generalized Random Tessellation Stratified (GRTS) Spatially Balanced Survey Design. Benthic macroinvertebrate samples will be collected one time at each probabilistic site during the two-year cycle, where sampling protocols apply.

The National Water Quality Initiative (NWQI) is a joint project of the USEPA and the USDA. The USDA's National Resources Conservation Service (NRCS) is providing financial assistance to farmers and ranchers throughout the Nation to implement conservation practices aimed at reducing nutrients, sediment, and pathogens in rivers and streams from agricultural lands. Three watersheds (HUC12s) were selected in New Jersey to receive this funding. With USEPA guidance, one of these watersheds, the Upper Salem River, was selected to receive focused monitoring, conducted by NJDEP-BFBM, to assess the effectiveness of these conservation practices in the watershed. Benthic macroinvertebrates will be sampled once a year for this project by BFBM from all sites. Along with the macroinvertebrate samples, there will also be nutrient, bacteriological, and chemical physical parameters collected for this initiative.

The United States Environmental Protection Agency (EPA) is working with its regional offices, states, tribes, and other entities to establish Regional Monitoring Networks (RMNs). The RMNs will help EPA and their partners collect current, baseline biological, thermal, and hydrologic data from freshwater wadeable streams. Benthic macroinvertebrates will be sampled once a year for this project by BFBM from all sites. Along with the macroinvertebrate samples, there will also be nutrient and chemical physical parameters collected for this initiative. This information will be used to help quantify and detect long-term changes in conditions of high-quality streams. Detection of such changes can inform water quality criteria and indicator development, as well as responses to climate change effects.