SETAC Globe - Environmental Quality Through Science
  21 January 2011
Volume 12 Issue 1

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Why Macrophytes Matter—Session Summary from the 2010 SETAC North America Annual Meeting

AMEG Advisory Group

The SETAC Advisory Group on Aquatic Macrophyte Ecotoxicology (AMEG) organized this platform and poster session to highlight the importance of aquatic plants to ecotoxicology, improving risk assessment, and sustaining ecosystem structure and function. For example, the importance of submerged aquatic macrophytes in maintaining ecosystem function and stability is well recognized by ecologists, but typically gets short shrift in ecotoxicology (Arts 42). This is reflected in the relative lack of standardized tests for these organisms to characterize toxicity for subsequent use in ecological risk assessment. Macrophytes can also destabilize ecosystems. For example, when aquatic plants become invasive outside their natural distribution area they can reduce biodiversity and imperil native macrophyte species, all resulting in a cascade of changes at higher trophic levels in terms of structure and function, including fish. The session’s aim was to discuss the benefits of aquatic plants and their role in lower and higher tier assessment as well as the risks invasive aquatic macrophytes pose to ecosystem structure and function. The science presented in Portland supports the development of principles and practices for protection, enhancement, and management of sustainable environmental quality and ecosystem integrity, as seen below from selected session highlights.

New testing approaches for assessing adverse responses in Elodea spp. and Myriophyllum spp. upon exposure to chemical contaminants and nanomaterials were discussed (Glenn 45, Brain TP083) with the aim of creating an Organization for Economic Cooperation and Development methodology for Myriophyllum spp. after a formal ring-test for the latter species in the coming year as a complement to standard duckweed (Lemna spp.) testing (Dohmen 46). An extensive evaluation of Lemna spp. toxicity data in species sensitivity distributions (SSDs) for macrophytes (currently an ongoing AMEG initiative) concluded that duckweeds appear to be variable in their relative sensitivity to the chemicals tested. Still, Lemna gibba was normally within a 10-fold range of responses, implying that current uncertainty factors applied in European assessments are protective of aquatic macrophytes (Giddings 47). The US Environmental Protection Agency is also looking into the use of macrophyte SSDs to set regulatory values with promising initial results (Dobbins 41). Work at the whole ecosystem-level highlighted the dynamic and transitory nature of macrophyte communities in both natural systems and those undergoing control measures for invasive species (Mebane 43, Poovey TP084). Timing, location and approaches to sampling will all color understanding of the community’s status, but even in those communities deemed to be highly impacted, recovery can occur rapidly in as quickly as a few weeks. All of the session’s presentations were relevant to the discussions at the AMEG meeting where Dr. Mark Sytsma of Portland State University elaborated on the science of controlling invasive aquatic plants. Protecting macrophytes and controlling them when deemed harmful are two sides of the same coin; they are asking similar questions but from two distinct perspectives, both with the aim of understanding how aquatic plants respond to stressors, how the ecosystem relies on these organisms, and how quickly native communities can re-establish themselves after being suppressed or extirpated. As AMEG moves forward and establishes relationships with other scientists working with macrophytes, it hopes to expand the scope and scale of its sessions, bringing in new voices to SETAC and improving the work we all do in the field.

Background information in:
Maltby L, Arnold D, Arts G, Davies J, Heimbach F, Pickl C, Poulsen V (2010). Aquatic Macrophyte Risk Assessment for Pesticides. SETAC Europe Workshop AMRAP, Wageningen, Netherlands. 135 pp. SETAC Press & CRC Press, Taylor and Francis Group, Boca Raton, London, New York.

Information about AMEG Advisory Group:
Arts, G., J. Davies, M. Dobbs, P. Ebke, M. Hanson, U. Hommen, K. Knauer, S. Loutseti, L. Maltby, S. Mohr, A. Poovey & V. Poulsen (2010). AMEG: the new SETAC advisory group on aquatic macrophyte ecotoxicology. Environ Sci Pollut Res 17(4):820–823.

AMEG communities website. This website is open for all SETAC members who select AMEG in their SETAC user profile. Please visit the AMEG community on and participate in discussions.

On the SETAC website you will also find information about our Advisory Group at

Abstract numbers and authors from this session are referenced above; full abstracts from the session can be found at:

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