PNAMP Briefing Paper
Exploring the relationships among macroinvertebrates, habitat,
and fish productivity for better monitoring outputs
Why Macroinvertebrates?
Freshwater macroinvertebrate (MI) assemblages, especially those collected in the benthic zone
of streams, have an established history of providing indicative value of in-stream habitat quality, and
demonstrating the effects of restoration activities (Stoddard et al. 1996, Miller et al. 2010, also see
PNAMP Macroinvertebrate Planning Group 2012). Members of the Macroinvertebrate Planning Group
(MPG) of the PNAMP Habitat Data Sharing Project, as well as others, are interested in exploring the use
of benthic MIs, as an additional indicator of habitat quality and expected fish productivity. This interest
stems partially from a need to better assess conditions for ecologically, culturally, and economically
important salmonids listed under the Endangered Species Act (ESA). In addition, there is growing
recognition that for ESA-listed fish simply assessing the in-stream physical habitat conditions without
accounting for their more comprehensive ecology—for example trophic relationships (ISAB 2011)—is
over-simplistic and bound to fail.
Currently MI assemblages have scant consideration in the assessment of fish productivity and
habitat quality for fish. Examination of the relationship among these attributes may inform the
development of improved metrics and/or indicators that are useful in assessing the effectiveness of
habitat restoration projects and/or in describing the value of a habitat toward fish productivity. This
briefing paper is intended as a call for discussion among the different communities of monitoring
practitioners to explore jointly this topic.
Simplified relationships among habitat, macroinvertebrates, and fish productivity.
The conceptual framework above illustrates, in a simplified way, the direct and indirect
relationships among habitat, MIs, and fish productivity. We adopt a broad definition of the term
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“habitat” to include in-stream conditions such as channel morphology, substrate composition, water
temperature, streamflow, and woody debris and near-stream and watershed components of habitat
such as riparian conditions, basin-wide land use and disturbance regimes, or the presence of legacy
toxins in agricultural land adjacent to the stream. As shown in the figure, habitat conditions have direct
effects on both (a) MI and (b) fish productivity. However, MIs and fish are also linked through (c) food
webs with benthic and drifting MI providing the food base for fish, fish depleting the abundance of MIs
via feeding, and MIs consuming salmon carcasses. The indirect link between MI and fish productivity via
(d) benthic MIs as indicators of fish habitat quality is the relationship of primary interest.
Benthic Macroinvertebrates as an Indicator
The PNAMP MPG encourages collective exploration of the relationship of MIs to habitat health
and fish productivity as a means to improve the availability and usage of MI, habitat, and fish
productivity data. MI indices are already used as an indicator of water quality and observations have
indicated that MI data could serve as an indicator in a broader context. Better understanding of these
relationships may provide insight into:


Trends between MIs and fish population productivity for ESA listed species
A measure of restoration effectiveness in improving habitat quality
What sort of collaboration do we need to explore these ideas?
The relationships among MI, habitat and fish productivity should be explored conceptually and
quantitatively. A first step is to expand mutual understanding of the ecological and monitoring
opportunities and issues linking MI, habitat, and fish productivity. These could be done in venues such
state chapter meetings of the American Fisheries Society. Beyond conceptual understanding is the need
for evaluation of data that quantitatively describes these relationships. This could be achieved by listing
available datasets which include benthic MI, habitat, and fish productivity measures; developing a
strategy to analyze these relationships; and assessing the results with respect to both the conceptual
framework and interest in an informative MI-habitat-fish indicator. For example, in 2012 aquatic
ecologists plan to analyze data from 50 ChaMP sites where MI and environmental data were collected
together. Other datasets exist that could provide additional insight into the strength of these
relationships, e.g. Oregon coastal coho ESU.
PNAMP staff seeks input from subject matter experts and the PNAMP Steering Committee to define
next steps.
Citations
ISAB [Independent Scientific Advisory Board]. 2011. ISAB Columbia River Basin Food Web Report, Document ISAB
2011-1. http://www.nwcouncil.org/library/isab/2011-1/.
PNAMP Habitat Data Sharing Macroinvertebrate Planning Group. Draft literature review. 2012. Available at:
http://www.pnamp.org/document/3836
Miller, S.W., P Budy, and J.C. Schmidt. 2010. Quantifying macroinvertebrate responses to in-stream habitat
restoration: Applications of meta-analysis to river restoration. Restoration Ecology 18(1): 8-19.
Stoddard, J. L., D. P. Larsen, C. P. Hawkins, R. K. Johnson, and R. H. Norris. 2006. Setting expectations for the
ecological condition of streams: the concept of reference condition. Ecological Applications 16:1267–
1276.
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