Variation in wetland invertebrate communities in lowland acidic fens and swamps

Abstract

1. Invertebrates were collected semi-quantitatively from four relatively undisturbed wetlands in the west coast of New Zealand's South Island: two acidic fens and two swamps. Samples were collected from up to four discrete habitats within each wetland: large open-water channels, small leads (small, ill-defined channels with emergent vegetation in them) and large (>10 m diameter) or small (<10 m diameter) ponds. Samples were also collected from different plant species within each wetland, each with different morphology, and from areas without vegetation. This was done to determine whether invertebrate communities varied more between-wetlands than within-wetlands, as the results had implications for future wetland monitoring programmes. 2. Principal components analysis of water chemistry data revealed striking differences in pH, conductivity and nutrients between the four wetlands. Not surprisingly, pH was lowest in one of the acidic fens, and highest in one of the swamps, where conductivity was also high. Midges (Tanytarsus, Tanypodinae, Orthocladiinae and Ceratopogonidae), nematodes, harpactacoid copepods and the damselfly Xanthocnemis dominated the invertebrate fauna. Orthoclad midges and mites were the most widespread taxa, found in 91 of 94 samples. Diptera were the most diverse invertebrate group, followed by Trichoptera and Crustacea. 3. Ordination analysis of the invertebrate data showed that the four wetlands supported different invertebrate communities. However, species composition did not change completely along the ordination axes, suggesting that a relatively species-poor invertebrate fauna was found in the wetlands. Taxa such as molluscs were restricted to wetlands with high pH. Multi-response permutation procedures (MRPP) was used to analyse resultant ordination scores to see how they differed according to five terms: 'Wetland', 'Habitat', 'Growth Form', 'Morphology' and 'Plant'. Most of the sample separation along ordination axes reflected differences between wetland, although the 'Habitat' and 'Plant' terms also explained some of the variation. The 'Growth Form' and 'Morphology' terms had only minor effects on community composition. 4. A multivariate regression tree modelled invertebrate assemblages according to the five predictor terms. The resultant model explained 54.8% of the species variance. The 'Wetland' term contributed most to the explanatory power, followed by 'Habitat'. 'Growth type' and 'Morphology' explained only a small amount of variance to the regression tree, while the different plant species explained none of the variation. 5. Variation in these New Zealand wetland invertebrate communities appears to be controlled most by large-scale factors operating at the level of individual wetlands, although different habitats within individual wetlands contributed slightly to this Correspondence: A. M. Suren, 727 variation. Based on these results, sampling programmes to describe wetland invertebrate communities do not need to sample specific habitats or plant types within a wetland. Instead,...

Mollusc communities of lowland rivers and oxbow lakes in agricultural areas with anthropogenically elevated nutrient concentration

“…in the oxbow lakes of the Warta River (PenczaK et al 2004) and the Odra River (SPałek 2008a). What is more, no such extremely high concentrations of nutrients as those recorded in the oxbow lakes of the Wkra River or in the Wkra River and its tributaries have been recorded to date (dussart 1976, strzeLec 1993, wILLIams et al 2003, PenczaK et al 2004, GaLLardo et al 2008, Suren et al 2008, Koc et al 2009, JurkiewiczKarnKowsKa 2011, ChaLuPová et al 2012, RIstau et al 2012, JIang et al 2013, PasztaLenIec & PonIewozIK 2013). However, hassaLL et al (2011 showed a maximum concentration of orthophosphates of up to 5.87 mg dm -3 in lentic water bodies -ponds (United Kingdom).…”

“…Some authors pointed out that the main environmental factors that acccounted for most of the variability in the mollusc community structure in floodplain water bodies including oxbow lakes were the physical and chemical parameters of the water, i.e. concentration of dissolved oxygen, chlorides, nutrients, permanence of the water body, its size and depth, types of bottom sediments, insolation and hydrological connectivity or even complexity of woody debris (aBraszewska-kowaLczyk 2002, schneIder & wInemILLer 2008, Jurkiewicz-karnkowska 2009, oboLewsKI 2011a, funK et al 2013). suren et al (2008 found that gastropods and bivalves (only Sphaeriidae) were restricted to wetlands (including ponds) with a higher pH and conductivity combined with a lower nitrite-nitrogen concentration (mean concentration of up to 3.50 µg N-NO 3 dm -3 in the water).…”

Are landscape-based wetland condition indices reflected by invertebrate and diatom communities?

“…Invertebrate samples were processed according to previous protocols (Suren et al 2007). Briefly, this involved washing the sample through a series of nested sieves (2, 1, 0.5, 0.25 and 0.062 mm) to remove larger animals and plant fragments, and identifying and counting all invertebrates retained on the coarse ([1 mm) and fine (0.062-1 mm) sieves.…”

“…Within each wetland, duplicate invertebrate samples were collected semi-quantitatively (standardised 2 min effort) from three discrete open-water bodies using a hand-held sweep net (0.3 mm mesh: Suren et al 2007). All invertebrate samples were preserved immediately following collection in 100% isopropyl alcohol.…”

Species richness and composition patterns of clitellate (Annelida) assemblages in the treeless spring fens: the effect of water chemistry and substrate

“…However, the question whether aquatic macroinvertebrates respond significantly to this ecological gradient is yet to be studied, because most existing ecological studies have not covered the entire length of the gradient (e.g. Erman & Erman, 1975;van Duinen et al, 2006;Suren et al, 2008).…”