Assessing the health of sediment ecosystems: use of
W. MAHER*, G. E. BATLEY AND I. LAWRENCE*
*Cooperative Research Centre for Freshwater Ecology, University of Canberra, ACT 2601, Australia
yCentre for Advanced Analytical Chemistry, CSIRO Energy Technology, Lucas Heights, NSW 2234, Australia
1. This paper outlines the use of chemical measurements as surrogate indicators of the
health of sediment ecosystems.
2. For chemical measurements to be used for this purpose, links must be able to be made
between adverse biological effects and the chemical composition of sediments.
3. Benchmark sediment quality guidelines allow decisions to be made about whether or
not a sediment ecosystem is likely to be impacted. These guidelines are established using
an effects database and a weight-of-evidence approach that gives ranges of chemical
concentrations associated with known adverse biological effects.
4. If guidelines are exceeded the measured values are compared to concentrations of that
contaminant in a comparable background or reference sediment. Exceedance of these
concentrations leads to site-specific estimates of contaminant bioavailability. If a potential
problem is indicated, laboratory sediment bioassays are used to assess the likelihood that
the sediment will harm biota.
5. Trace metals are used as an example of a sediment contaminant.
Keywords: sediment ecosystems, health, chemical measurements
A healthy sediment ecosystem may be defined as one
that supports an active and diverse biological popula-
tion, and functions satisfactorily. This means that
sediments should not contain chemical constituents
that impair the growth and function of their depen-
The health of sediment ecosystems can be assessed by
measuring the structure and abundance of their
biological communities, by laboratory bioassays, or
by using surrogate chemical measurements that can be
related to contaminant bioavailability and adverse
effects. The first of these measures is typically time-
consuming and expensive, so there is impetus for the
development and application of meaningful chemical
measurements. This has formed the basis of the
development, in many countries, of sediment quality
guidelines (Environment Canada, 1995; MacDonald
et al., 1996a; ANZECC and ARMCANZ 1998). The
guidelines are designed to identify those sediments
where the concentrations of contaminants should not
cause adverse biological impacts, as distinct from those
laboratory data that demonstrate associations between
the presence of chemicals and adverse biological effects.
This paper describes ways in which chemical
measurements and sediment quality guidelines can
be used to assess sediment ecosystem health. It gives
an overview of the heterogeneous nature of sedi-
ments, and describes how sediment ecosystems
function and affect contaminant bioavailablity. Trace
metals provide an example of a sediment contami-
nant. As well, we define our concept of a healthy
sediment ecosystem, and explore some of the diffi-
culties presented by the use of chemical and biological
measurements to assess health.
Freshwater Biology (1999) 41, 361±372
ã 1999 Blackwell Science Ltd.
Correspondence: W. Maher, Cooperative Research Centre for
Freshwater Ecology, University of Canberra, ACT 2601, Aus-