A Comparison of the Efficacy of Pond-Net and Box Sampling Methods in Turloughs – Irish Ephemeral Aquatic Systems

Abstract

Two methods were used to sample aquatic macroinvertebrates in three turloughs. Turloughs are systems that flood periodically from groundwater, in response to local rainfall patterns and contain rare aquatic species and assemblages. The first method used a standard pond net that was swept through the water column, while the second involved fixing a rectangular, open-bottomed box to the substrata and removing all organisms with a net. Similar overall sampling effort was applied to each method and individual box samples were found to take longer to gather than pond net samples. The box method, however, gave the maximum yield for a given sampling effort. Significantly more beetle species and individuals were recorded per unit area of bottom at all three turloughs using the box method. Multivariate analysis segregated samples, firstly according to site and secondly, with respect to method. The box method is a viable alternative to sampling with a pond net. It is more quantitative, objective, specific and reliable. This is particularly important in habitats distinguished by rare species and assemblages, and for which monitoring is driven by legislative needs.

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“…The same result stated also by O´Connor et al (2004) in Irish turloughs. This can influence the assessment of macroinvertebrate diversity at investigated localities.…”

“…The same authors documented the importance of nekton, in which category belong also corixids and chaoborid larvae, within the shallow wetland macroinvertebrate communities. O´Connor et al (2004) stated that the box method captured more taxa than a pond-net and it was successful especially in sampling aquatic beetles in dense vegetation. Other additional suitable method for capturing fast-moving invertebrates (e.g., corixids, beetles) is activity traps (Hyvönen and Nummi, 2000;Becerra Jurado et al, 2008), which are more successful especially in dense stands of emergent vegetation and enable better estimation of biodiversity at study sites (Becerra Jurado et al, 2008).…”

“…Gerking frame box sampler demonstrated its suitability for quantitative sampling in hard emergent vegetation of pond littorals, although it is a more labour consuming method compared to sweep netting (also O´Connor et al, 2004). Sweep net is usually recommended as a better sampling method for capture more macroinvertebrate taxa than other techniques (Cheal et al, 1993, García-Criado andTrigal, 2005).…”

“…Detailed comparisons of efficiency among various types of samplers were reported (Gillespie and Brown, 1966;Kaminski and Murkin, 1981;Downing and Cyr, 1985;Muzaffar and Colbo, 2002;O´Connor et al, 2004;García-Criado and Triado, 2005) but most of these studies were conducted only on soft submersed macrophytes or sediments.…”

Distribution and diversity of littoral macroinvertebrates within extensive reed beds of a lowland pond

“…Of a number of possible sampling methods, hand sweep netting seemed to be a suitable and representative method, which provides good and quick semiquantitative data acquisition for the assessment of aquatic macroinvertebrate diversity and abundance in dense reed beds (O'Connor et al, 2004;Garcı´a-Criado and Trigal, 2005;Sychra and Ada´mek, 2010).…”