TROPHIC DIATOM INDICES (TDI) AND THE DEVELOPMENT OF SITE-SPECIFIC NUTRIENT CRITERIA
Abstract:In 2004 a four year study performed for NJDEP by the Patrick Center for Environmental Research showed that trophic diatom inference models could be used effectively to assess late-summer nutrient concentrations and benthic algal responses specific to different physiographic provinces in the state. Diatoms are widely recognized and used as indicators of river and stream water quality because benthic diatom species composition responds directly to nutrients and can be a more stable indicator of tropic state than measurements of nutrient concentrations or algal biomass (e.g., chlorophyll a). Objectives of the study were to: 1) develop New Jersey specific field and lab protocols for characterizing eutrophication (nutrient concentrations) in streams using attached periphyton algae, 2) assess the relationships between stressors (i.e., total phosphorus/nitrogen) and overt signs of eutrophication (e.g., algae), and 3) develop biological metrics as potential biocriteria (e.g., diatom community structure and trophic diatom indices - TDI). We chose weighted average inference modeling as our approach because it incorporated the most accurate method for quantifying species response to nutrients. We used nutrient concentrations inferred from the models in two ways: 1) directly, by using the inferred diatom values as estimates of the nutrient concentrations prevailing at the site during the time the algal assemblages were developing, and 2) indirectly, by rescaling the inferred concentrations from 0–100 to create trophic diatom indices (TDI) more easily interpretable by non-specialists. In the current study in 2004 we performed a pilot study to test the TDIs above and below two Sewage Treatment Plant (STP) facilities in New Jersey to evaluate their usefulness as a stressor-response model necessary to generate site-specific biocriteria for nutrients. We conclude that the TP and TN diatom inference models and indices are promising tools to monitor and infer nutrient conditions but that further study is necessary to adequately evaluate their effectiveness for routine use as part of a regulatory program. Diatom community composition differed among sites, and the differences can be explained by variation in nutrient concentrations. Diatom indices indicated relatively high nutrient conditions at all sampling sites, and between-site differences were consistent with measured values. Both the diatom indicators of enrichment and the measured nutrient concentrations showed a marked increase below one STP, but not below the other. This may be because the discharge from one plant was much greater than the other, one-time sampling did not represent longer-term nutrient conditions, or there are other important, unaccounted-for factors influencing nutrient concentrations.
Document Type: Research Article
Publication date: 2005-01-01
More about this publication?
- Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed. A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.
WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
- Subscribe to this Title
- Membership Information
- About WEF Proceedings
- WEFTEC Conference Information
- Learn about the many other WEF member benefits and join today
- Ingenta Connect is not responsible for the content or availability of external websites