Grantee Research Project Results
Final Report: An Integrative Aquatic Ecosystem Indicator
EPA Grant Number: R826591Title: An Integrative Aquatic Ecosystem Indicator
Investigators: Stemberger, Richard S. , Miller, Eric K.
Institution: Dartmouth College
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1998 through June 30, 2003
Project Amount: $888,661
RFA: Ecological Indicators (1998) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
The main objective of this research project was to develop an integrative indicator for lakes that draws upon key relationships among zooplankton assemblage or body size structure, and lake chemistry and morphometry, with tributary chemistry and watershed vegetation land cover.
Historically, zooplankton have been neglected in routine lake monitoring programs, despite their key role in grazing and as a food resource for fish. Indicators of the middle food web are conspicuously absent from the majority of lake monitoring programs.
Quantitative zooplankton indicators based on population abundances have been too costly to implement and have required much technical specialization. Furthermore, analyses usually are complex, and results often have been too difficult to interpret to truly be useful for typical monitoring applications. Therefore, we have attempted to develop and test new formulations of zooplankton indicators in an effort to establish clear relationships to valued lake qualities such as water transparency, fish population size structure, and lake trophic state. Although we are still in the analytical stages of this project, we have important results that merit consideration for lake monitoring applications.
Summary/Accomplishments (Outputs/Outcomes):
Cladoceran Body Size–Relationship to Secchi Transparency and Fish Population Size Structure
Secchi disk transparency is the most commonly measured optical property of lakes and is widely used to assess lake trophic condition and to monitor long-term trends in water clarity. We have developed a simple body-size indicator that helps explain a significant portion of the variation in Secchi disk measurements for within-lakes temporal measurements and for measurements across populations of lakes (Stemberger and Miller, in press 2003) (see Figure 1).
The indicator tracks the underlying relationship between cladoceran grazing efficiency (the capacity to remove suspended particles like algae and detritus) and Secchi transparency depth. Cladocerans are among the most important components of the grazer community. By including only the cladocerans in this indicator, we have greatly simplified the assemblage components and reduced the effort, time, and cost in sample processing.
The indicator also captures the relationship between mean cladoceran body size and intensity of fish predation. Hence, it provides insight into fish population size structure that otherwise is difficult and costly to assess. A change in trophic condition such as a significant increase in chlorophyll a concentrations or decrease in Secchi transparency could be attributed to either an increase in nutrient loading from the watershed or to a decrease in the grazing pressure that might signify an overall decrease in grazer assemblage body size. An assemblage characterized by small cladoceran body sizes could indicate over-harvesting of top game fishes (loss of control on forage fish population) or degradation of deep water habitat (loss of cool water piscivores). The body size indicator will permit lake managers to distinguish between these two competing possibilities.
The indicator is easy to produce, not only because of the image processing technology that we employ but also because sample processing does not rely on costly and time-consuming species counts. Our technique is relatively easy to do and requires minimal training in taxonomy. One needs to know the shapes of the four primary functional groups and which dimensions constitute specimen body length. The computer program does most of the work. The zooplankton sample relies on a single, vertical net haul taken from the bottom to the surface at the deep location in the lake.
Figure 1. Predicted Versus Observed Secchi Disk Transparency Values in Multiple Regression With Particulate Carbon, Color, and Cladoceran Mean Length as Independent Variables. R2 = 0.85, F = 88.66. Solid lines denote 0.95 prediction bands, and broken lines denote 0.95 confidence intervals. N= 51. Closed circles = mean cladoceran length < 0.6 mm, and open circles = mean cladoceran length > 0.6 mm. Note that large-bodied cladocerans may be associated with low Secchi transparency values when color or concentrations of organic particulates are high.
Zooplankton Indicators for Regional Lake Monitoring
We completed a study of the variance structure of zooplankton population indicators for the regional sampling in the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP). This analysis demonstrates that zooplankton are valid indicators for regional monitoring, having a variance structure (lake, year, lake-year interaction, and error components) that is comparable to other biological assemblages like fish and macroinvertebrates (Stemberger, et al., 2001). Hence, we conclude that zooplankton abundance variables are suitable indicators for monitoring of regional lake status and trend detection.
Integrating Zooplankton, Lake, Tributary Chemistry, and Watershed Land Cover
We currently are analyzing and evaluating the watershed land and stream chemistry datasets to establish relationships with zooplankton assemblage and body size structure and lake chemistry. We have established that tributary chemistry weighted for the area of its sub-watershed and watershed vegetation and land cover are strong predictors of lake water chemistry (65-88 percent of explained variance). Up to 40 percent of the explainable variance in zooplankton assemblage structure can be related to watershed land cover.
Journal Articles on this Report : 3 Displayed | Download in RIS Format
Other project views: | All 27 publications | 12 publications in selected types | All 11 journal articles |
---|
Type | Citation | ||
---|---|---|---|
|
Stemberger RS, Miller EK. A zooplankton- N:P-ratio indicator for lakes. Environmental Monitoring and Assessment 1998;51(1-2):29-51. |
R826591 (1999) R826591 (2000) R826591 (2001) R826591 (2002) R826591 (Final) |
not available |
|
Stemberger RS, Larsen DP, Kincaid TM. Sensitivity of zooplankton for regional lake monitoring. Canadian Journal of Fisheries and Aquatic Sciences 2001;58(11):2222-2232. |
R826591 (2001) R826591 (2002) R826591 (Final) |
not available |
|
Stemberger RS, Miller EK. Cladoceran body length and assessment of Secchi disk transparency in Northeastern U.S. lakes. Canadian Journal of Fisheries and Aquatic Sciences 2003;60(12):1477-1486. |
R826591 (Final) |
not available |
Supplemental Keywords:
zooplankton assemblage structure, zooplankton body size, lake trophic state, Secchi disk transparency, tributary chemistry, water chemistry, watersheds, limnology, ecology, ecological effects, ecosystem, indicators, aquatic, terrestrial, Environmental Monitoring and Assessment Program, EMAP, geographic information systems, GIS, northeast lakes., RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Nutrients, Ecology, Hydrology, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Environmental Chemistry, Ecological Effects - Environmental Exposure & Risk, Air Deposition, Drinking Water, Geology, Watersheds, Ecological Indicators, nutrient transport, aquatic ecosystem, environmental monitoring, nutrient supply, ecological effects, ecological exposure, risk assessment, EMAP, carbon cycling, algae, multi-level indicators, bioavailability, other - risk assessment, algal growth, chemical transport, ecosystem indicators, terrestrial, aquatic ecosystems, phosphorus, carbon storage, integrative indicators, lake ecosystem, landscape characterization, land use, nitrogen, atmospheric depositionProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
- 2002 Progress Report
- 2001 Progress Report
- 2000 Progress Report
- 1999 Progress Report
- Original Abstract
11 journal articles for this project