Is there an ideal protocol for sampling macroinvertebrates in springs?

Abstract

Sampling in springs has several technical problems due to their reduced dimensions and habitat heterogeneity. A standardized quantitative method for sampling crenic macroinvertebrates has never been proposed. The aim of this study was to compare different sampling methods and consider their environmental impacts. First, we present a review of sampling methods found in the literature and discuss their advantages and disadvantages with respect to selective collection of the target community and habitat disturbance. Altogether, 10 different methods have been reported, the use of nets being the most common protocol. Second, we report the results of macroinvertebrate samplings performed in three springs, each surveyed twice, using three different methods (multi-habitat proportional hand net, baited traps, and vegetation washing), in order to compare their effectiveness in collecting macroinvertebrates. Overall, 32 macroinvertebrate taxa, mostly identified at family level, were collected in the sampled springs. Significant differences in abundances were found using different methods, while results for community structure were comparable between the hand net sampling and the combined use of the other two methods, notwithstanding slight differences in the composition of Coleoptera and Diptera assemblages. The hand net, with a multi-habitat proportional approach, yielded more thorough results, making it suitable for biodiversity inventories but having some potentially negative effects on spring habitats. Traps and vegetation washing are also reliable methods with negligible impacts on spring ecosystems that can be conveniently used in ecological studies.

A modification of the leaf-nets method for sampling benthic invertebrates in spring habitats

“…Our study confirms the higher efficiency of active methods (Surber net) in collecting more individuals and more taxa in spring habitats (Rosati et al, 2016). However, no differences between Surber and LN samples were found for the number of insect taxa and Simpson's diversity.…”

“…Moreover, compared to other passive (semiquantitave) methods (Sangiorgio et al, 2010;Bottazzi et al, 2011;Rosati et al, 2016), leaf-nets seem to collect more information on the structure of spring communities.…”

“…The choice of appropriate sampling methods and the relative sampling effort are the main discriminating factors which determine the accuracy of the information (Humphries et al, 1998;Pinna et al, 2014). Studies comparing the efficiency of different sampling methods were performed for streams, shallow freshwater ponds and transitional waters (see for review , 2015 but are nearly absent for spring habitats (but see Cantonati et al, 2008 andRosati et al, 2016).…”

“…All available sampling methodologies for spring habitats were recently reviewed by Rosati et al (2016). Active methods (Surber net, hand-kick net, moss and vegetation washing, Bou-Rouch pump, core sampler) seem more efficient compared to passive ones (light traps, emergence traps, drift nets, artificial substrates).…”

The ecology of narrow-range endemic macro-invertebrates of Great Artesian Basin springs

“…Data concerning the patterns of abundance and distribution of invertebrate species, and ongoing monitoring programs concerning species within the threatened community in general are rare, and those that do exist, employ different sampling methodologies that may render comparisons across species, across different types of taxa or across different regions inaccurate due to methodological biases (Cantonati et al, 2007;Cheal et al, 1993;Rosati et al, 2016). Current conservation practices generally focus on local scales, and rest heavily on stock exclusion and attempts to eradicate invasive flora and fauna Kodric-Brown & Brown, 2007;.…”