Use of sequential sampling of amphipod abundance to classify the biotic integrity of acid-sensitive lakes

Abstract

/ A sequential sampling program using previously published zoobenthos data is described for ubiquitous, costeffective biomonitoring of the effects of lake acidification.Spring densities of the littoral amphipod Hyalella azteca are quantitatively sorted into five abundance catagories. An essential step in the a priori definition of decision criteria is the stratification of proportional densities per unit macrophyte biomass in relation to aqueous total phosphorus concentrations. Density rankings were related to lake acidity and to detailed lake-specific information on patterns of Hyalella life history and acid tolerance. Incorporation of Hyalella abundance as a potential metric for the assessment of the biological integrity of acid-sensitive waters is recommended. The temporal integration of transient changes in spring meltwater chemistry is an important rationale for the development of such biomonitoring procedures.Environmental scientists greatly err in assuming that measures of aqueous chemical imbalance alone are sufficient to gauge ecosystem stress (Karr 1987). Living organisms provide convenient full-time monitors of transient variability in environmental quality, an important consideration when assessing the effects of anthropogenic acidification on lakes and rivers in north-temperate climates. Because the soil in such regions may still be partially frozen in the spring, much of the acidic snowmelt can run off quickly with little neutralization taking place within the watershed. For example, typically between 36% and 77% of the annual export of H + from watersheds over much of central Ontario occurs during this short interval (Jeffries and others 1979). Due to logistic difficulties, acidic pulses are rarely monitored throughout the littoral zone over the melting period. More frequently, if the spring episodes are sampled at all, they are normally estimated from midlake stations or inferred from the more accessible outflows, which are assumed representative of the lake as a whole. Such measures are at best, however, an imprecise reflection of the actual environment to which littoral organisms are exposed, and misleading conclusions regarding the severity of such pulses can arise (France and LaZerte 1987). Obviously, the function of biomon-

Evaluating the effects of spatial monitoring policy on groundwater quality portrayal

“…Veneziano and Kitanidis (1992) explored a similar question, recommending sequential sampling decisions to assess the accuracy of predictive contour mapping of ore bodies, and to create optimal sampling strategies. France (1992) applied sequential sampling to biotic classification of acid-sensitive lakes. I used an iterative or sequential approach, in part (Rouhani 1985, Loaiciga 1989, where "sampling sites were added.., until" there is little "additional gain in statistical accuracy" or "variance in estimation" (Loaiciga 1989, France 1992.…”

“…France (1992) applied sequential sampling to biotic classification of acid-sensitive lakes. I used an iterative or sequential approach, in part (Rouhani 1985, Loaiciga 1989, where "sampling sites were added.., until" there is little "additional gain in statistical accuracy" or "variance in estimation" (Loaiciga 1989, France 1992. The variance in estimation is measured in this research with regression products.…”

Production and turnover ofHyalella aztecain central Ontario, Canada compared with other regions

“…France, unpublished). All subsequent analyses and discussions pertain only to this particular habitat region (see France, 1990;France, 1992c).…”

A multi-taxonomic indicator of acidification: isolating the effects of pH from other water-chemistry variables

“…Living organisms provide the only means for assessing the toxicity of environmental pollutants. As a consequence, considerable effort has been directed towards the establishment of biological indicators for assessing the impact of acidification on freshwater systems (e.g., Raddum and Fjellheim 1984;Mills and Schindler 1986;Merilainen and Hynynen 1990;France 1992). Approaches have included both laboratory bioassays (Havas 1981;Levin and Kimball 1984) and field studies (e.g., Harvey and McArdle 1986;Bradt and Berg 1987;Hamalainen and Huttunen 1990).…”