Physiological indicators of fitness in benthic invertebrates: a useful measure for ecological health assessment and experimental ecology

Abstract

Physiological indicators of fitness present a measure of an organism's response to a changing environment. An analysis of how these organisms allocate and store their energy resources provides an understanding of how they cope with such environmental changes. Each individual has to balance the investment necessary to acquire a certain resource with the energy gained by it. This trade-off can be monitored by measuring several physiological indicators of fitness such as energy storage components, metabolic state or RNA/DNA ratio. Because environmental adaptations and ecological strategies of survival are best examined within the natural environment, our research has to rely on the physiological indicators that are easily accessible in the field. The physiological indicators presented here are significant for an individual's fitness and in turn lead to reliable values in field-collected samples. Based on our own expertise and on a literature survey, the physiological relevance of the presented indicators is explained. Furthermore, some consideration to the analytical methods used to obtain the physiological indicators is given, and possible errors introduced at the sampling site and during the laboratory procedures are discussed. This work demonstrates that the integration of ecological and physiological expertise facilitates the identification of future ecological problems much earlier than separate approaches of both disciplines alone.

Herbicide indirectly reduces physiological condition of a benthic grazer

“…Hence, we deduced a NOEC TG of 0.03 µg l −1 (0.06 µg l −1 nominal) and a LOEC TG of 0.21 µg l −1 (0.6 µg l −1 nominal) for an indirect effect of terbutryn on the physiological condition of grazers. This result underlines the high sensitivity of this endpoint to environmental changes and supports the view that it might be a good measure for subtle effects of biotic and abiotic factors in further laboratory and environmental studies (Koop et al 2011).…”

“…Also, the direct comparison of absolute triglyceride levels between the terbutryn experiment and the emergence experiment would not be meaningful, due to the different life stages used (larvae vs. adults) and the accompanying differing triglyceride levels (Cargill et al 1985, Servia et al 2006, Winkelmann & Koop 2007). However, a reduction of triglycerides of about 24% is still a clear indication of a reduced energy uptake; especially considering that triglycerides are the major energy store of mayflies and, hence, the main indicator of physiological fitness (Koop et al 2011), as shown for Rhithrogena semicolorata, Ephemera danica (Winkelmann & Koop 2007) and Heptagenia flava .…”

The relative importance of diet-related and waterborne effects of copper for a leaf-shredding invertebrate

“…For instance, since gammarids require lipids for reproduction (Glazier, 2000;Plaistow et al, 2003), the observed lower lipid content may be indicative for a lower reproductive capacity (Koop et al, 2011), which may finally result in a lower abundance and in consequence lower contribution of Gammarus to local leaf breakdown.…”

Growth Rates of Microbes in the Oceans

“…The rRNA:rDNA ratio is then an index of the growth rate for a particular taxon classified by its 16S rRNA gene sequence. RNA content is also used in ecological studies of fish and invertebrates (Ciotti et al 2010, Koop et al 2011.…”