Conducting the Environmental Impact Analysis and Assessment - Environmental Impact Analysis: Process and Methods - page 200

Heat
exchanger
Water
output

Mixer

Water
input

Tank diameter
Tank height
Water surface area
Depth of water
Volume of water
Area sediment
Depth of sediment

1.83 m
5.49 m

Sediment

2.63 m 2

5.00 m

13.1 m 3
2.52 m 2

0.37 m

FIGURE 5.13
Marine Ecosystem Research Laboratory (MERL) experimental tank. (Adapted from Sampou, P.
and Oviatt, C.A., J. Mar. Sci. , 44, 1991.)

the ecosystem characteristics (e.g., water chemistry, productivity, biological
populations) monitored periodically, and in some cases daily. The research
facility was designed and is ideally suited to measure the response of estua-
rine ecosystems to various degrees of human perturbations because condi-
tions are virtually identical among mesocosms except for the variable under
consideration.
During the late 1970s and 1980s, a series of MERL experiments were con-
ducted to measure ecosystem response to loading gradients of the primary
pollutants associated with treated municipal wastewater (i.e., nutrients and
organically rich solids). One set of experiments focused on nutrients only
(Oviatt et al. 1986) and another on the organic load and nutrients associ-
ated with wastewater solids (Oviatt et al. 1987, Sampou and Oviatt 1991, and
Maughan and Oviatt 1993). The purpose of these experiments was to deter-
mine whether there was a direct and quantifiable relationship between pol-
lutant loading and the response of individual components of the estuarine
ecosystem (e.g., chemistry, water column biota, production, and benthic com-
munity). The measured responses of the individual components could then
be evaluated to determine the integrated ecosystem response. The nutrients
and solids were added daily to the mesocosms at rates from double up to six-
teen times the estimated input to a relatively unstressed estuary (Figure 5.14)
using lower Narragansett Bay, with low residential development density and
little agricultural input, as a standard for a low stressed condition.
The results of all the experiments demonstrated a strong relationship
between pollutant loading and ecosystem response and clearly indicated