Phantom midge-based models for inferring past fish abundances

Abstract

We sampled living and subfossil phantom midge (Diptera: Chaoboridae) larvae from surface sediments of 21 small lakes in Southern Sweden to examine the influence of fish and selected abiotic variables on the abundance and species composition of chaoborid assemblages. We expected total Chaoborus abundance to be inversely correlated with fish abundance and Chaoborus species most sensitive to fish predation to be found only in fishless lakes. We aimed to use the observed relationships to develop models to reconstruct past fish abundances from chaoborid remains and the abiotic environment. C. flavicans occurred in almost every lake, whereas subfossil C. obscuripes were found in the surface sediments of only one fishless lake. The density of living C. flavicans larvae correlated negatively with fish abundance, lake order and size. The concentration of C. flavicans subfossils was negatively associated with pH, lake size, water transparency and fish abundance. Regression models that included lake morphometry and landscape position as additional predictors of fish abundance performed better than models that used only Chaoborus predictors. The explained variance in fish abundance varied from 52 to 86%. Leave-one-out cross-validation indicated moderate performance of the two best models. These models explained 51 and 56% of the observed untransformed fish density and biomass, respectively. In addition, all Chaoborus models were unbiased in closely following the 1:1 reference line in plots of observed versus predicted values. These results are a promising step in developing midge-based paleolimnological reconstructions of past fish abundance, and the approach might be improved by including chironomid remains in the models.

Fossil chironomid assemblages and inferred summer temperatures for the past 14,000 years from a low-elevation lake in Pacific Canada

“…Below this, Chaoborus mandibles exceed 3% only once. Mandible concentrations are low with a maximum of only 6 individuals/cm , which is comparable to concentrations at some sites (Uutala 1990), but orders of magnitude less than at others (Palm et al 2012;Tolonen et al 2012). Mandibles in most samples are either Chaoborus flavicans or C. trivittatus.…”

“…The sedimentary remains of Chaoborus species have been used in paleolimnological studies as a proxy for fish presence (e.g. Uutala 1990;Lamontagne and Schindler 1994;Uutala and Smol 1996;Palm et al 2012) and even fish biomass and population density (Tolonen et al 2012). The basis for this approach centers on whether Chaoborus species are capable of diurnal migration to avoid predation by fish, which is the case in C. flavicans and C. trivittatus (Uutala 1990).…”

Topical advances and recent studies in paleolimnological research

“…Fossil invertebrate remains reveal information about food-web structures, predatorprey dynamics, and they are useful for investigating the influence of invertebrate competition and predation on zooplankton size structure (Alexander and Hotchkiss, 2010). Invertebrate remains have been used to document the presence or absence of fish, often for specific fish families (e.g., Cyprinidae), to identify changes in fish planktivory, and to examine keystone fish predation (Palm et al, 2011;Tolonen et al, 2012;Twining and Post, 2013;Labaj et al, 2013). The use of these fossils to address aquatic trophic-web questions often relies on contemporary limnological information about zooplankton community structure in lakes with and without fish.…”

“…The use of these fossils to address aquatic trophic-web questions often relies on contemporary limnological information about zooplankton community structure in lakes with and without fish. For example, Tolonen et al (2012) used modern and fossil phantom-midge data to derive Chaoborus-based regression models for small Swedish lakes, and to reconstruct past changes in fish biomass and density. Their study demonstrated the usefulness of certain chaoborid taxa as indicators of limnological conditions, such as basin morphometry and water transparency.…”

Towards a more precisely defined macrophyte-dominated regime: the recent history of a shallow lake in Eastern Poland

“…appeared and occurred in high percentages. Their coexistence with fish requires low water clarity (Wissel et al, 2003;Tolonen et al, 2012). The appearance of Chaoborus sp.…”