ECASA WP 2
Annotated sheet for indicators1
related to the impact of aquaculture on the environmenti
1- Name of indicator, authors
Sediment carbon quality (Rp index) (Kristensen, E)
Proposed by Kenny Black, SAMS.
2- Computation : Formulae, or model output.
Whenever possible, please use a range of 0-100. Ranking the results in few classes (five?) is
another option for qualitative indicators.
Rp = (%LOI@500/(%LOI@500+%LOI@250)) giving values in the range 0-1.
Where %LOI@250 = the % loss of weight of a sediment sample (freeze dried, from which is derived an
additional indicator: Water Content) after 16h at 250C (operationally defined as Labile Carbon)
Where %LOI@250 = the % loss of weight of the same sample heated for a further 16h at 500C (operationally
defined as Refractory Carbon)
3- List of data / parameters required for computation.
Simple measures of sample weight pre- and post-combustion.
4- Description of scientific meaning, references
Rp index is based on measurements of Loss on Ignition (LOI), which is equivalent to Total Organic Carbon
Kristensen, E. and Andersen, F. O. (1987) Determination of Organic-Carbon in Marine-Sediments - a
Comparison of 2 CHN-Analyzer Methods. Journal of Experimental Marine Biology and Ecology 109, 15-23.
Kristensen, E. (2000) Organic matter diagenesis at the oxic/anoxic interface in coastal marine sediments, with
emphasis on the role of burrowing animals. 426, 1-24.
Loh, P. S., Reeves, A. D., Overnell, J., Harvey, S. M. and Miller, A. E. J. (2002) Assessment of terrigenous
organic carbon input to the total organic carbon in sediments from Scottish transitional waters (sea lochs):
methodology and preliminary results. Hydrology And Earth System Sciences 6, 959-970.
5- Range of validity; please provide a description of the field of validity for the
indicator, its limits, endpoints. Careful explanations should be given in a table
about the correspondence between the computed values and the impact (from
positive effect, no impact , moderate impact, high impact, unacceptable impact).
1
Please return these sheets to the WP 2 leader, BEFORE end of March 2005.
This has not been well established in the literature for aquaculture, but there is a good literature of correlations of
Rp with e.g. distance from land. Studies by Dean (PhD Thesis, SAMS, 2005) have shown a good correlation
between the lability of sedimentary OM as estimated by %LOI@250 and depth in sediment under a salmon farm.
This indicator may be useful coupled to DEPOMOD output with the G-model of carbon degradation switched
on. DEPOMOD model development to allow prediction of Rp is underway outside ECASA.
The main advantange of this indicator is that it requires very simple apparatus (an oven) and is therefore low in
cost. Many samples can be processed at the same time.
6 -Type of aquaculture on which this indicator applies
The indicator applies to all forms of carbon loading on sediments.
6- Relevant environments for this indicator
All intertidal and subtidal environments where it is possible to sample sediments.
8- Quotation. We will need to select the most appropriate indicators to be proposed for
EIA and site selection. Please suggest a quotation for this indicator for the following
criteria (from A, perfectly adequate, to E, not relevant), to help evaluating the
indicator within WP 4. Additional comments are welcome.
 Direct relevance to objectives : The indicator selection must be closely linked to the
Requirements of the EU: Use for environmental impact assessment and site selection.
This aspect should be detailed.
 Clarity in design.
It is important that the selected indicators are defined clearly in order to avoid confusion
in their development or interpretation.
 Realistic collection or development costs : Indicators must be practical and realistic,
and their cost of collection and development therefore need to be considered. This
may lead to trade-offs between the information content of various indicators and the
cost of collecting them.
 High quality and reliability : Indicators, and the information they provide, are only
as good as the data from which they are derived.
 Appropriate spatial and temporal scale : Careful thought should be given to the
appropriate spatial and temporal scale of indicators.
 Obvious significance : The meaning and usefulness of the indicator should easily be
understood by stakeholders. They would preferably use the levels of dissolved
oxygen, rather of sulphide concentrations.
9- Data and models related to this indicator, available for use by WP 4. Please list the
data and models output available at local, national or regional scales for use by ECASA.
They may not correspond to the more theoretical list asked for in §3.
There are some data in the literature but generally little for fish farms. It might be expected to work very well in
fish farms owing to the high flux of labile OM to sediments, and it should be possible to use this to evaluate
recovery status. This indicator is less complex and time-consuming than TOC measurements, which are
routinely carried out in EIA studies yet correlate very poorly with impact as TOC includes both labile and
refractory material.
10- Suggestions for use by WP 5. Give examples of indicators/aquaculture/environments
which can be field-tested during the course of WP 5.
This index could easily be measured in any sampling scheme involving sediments. Ideally several cores on
a transect from a fish farm would be sliced (e.g. at 1 cm intervals to 10-15 cm depending on accumulation
rate) but it may be sufficient to take surface samples only where grabs are being deployed rather than cores.
This could be determined within the project.
This document is intended to be used for internal work on ECASA workpackage. The final
indicator sheet may include a format somewhat different. Please suggest any improvement for
both the content and the form of this document.
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