An exploration of the relationships betweenmacroinvertebrate community composition and physical andchemical habitat characteristics in farm dams

Abstract

Recently, Australian interest in farm dams has focused on rates of harvest of surface waters (runoff), and the impact this has on nearby natural systems. Little research has been directed towards the role of these artificial water bodies in sustaining biological reserves within the wider ecosystem. Macroinvertebrate communities in three farm dams in the Central Tablelands of New South Wales were surveyed, and water quality variables were correlated with species richness and abundance. Community responses to habitat factors including sediment depth, stock use, vegetation and debris were also examined. Communities were described at several taxonomic levels in addition to allocation to trophic groups and primary functional feeding groups. Species richness and abundance of communities were found to vary between dams and between habitat types within dams. The extent of these differences was decreased when communities were described by either trophic status or functional feeding mechanisms. Habitats were influenced by water quality and by physical features of the habitat, with the two factors interacting to define equilibrium conditions. Localised conditions resulted in different macroinvertebrate communities. Physicochemical parameters that correlated most closely with communities included light penetration, chlorophyll-a and conductivity. Habitat factors that were most frequently linked with communities were sediment depth and canopy cover, with localised disturbances related to stock use affecting feeding groups rather than specific taxa. One of the major problems associated with increasing modification of landscapes by agriculture or urbanisation is the fragmentation of undisturbed habitats. Creation of joint aquatic and woodland habitats enhances biodiversity corridors. The recognition of the potential for farm dams as reservoirs of biodiversity and development of management practices that optimise this neglected biodiversity reserve may have much wider benefits biologically, aesthetically and productively.

Selection of ecological indicators for the conservation, management and monitoring of Mediterranean coastal salinas

“…The physical and chemical conditions in a given habitat will support a characteristic set of richness and diversity levels of macroinvertebrate species (Heino 2000;Brainwood and Burgin 2006). In the salinas studied, macroinvertebrate diversity differentiates the evaporating ponds from the others and can be considered as a good indicator of these saline environments.…”

Hotspots of biodiversity or homogeneous landscapes? Farm dams as biodiversity reserves in Australia

“…Brainwood and Burgin (2006) found that water quality and physical habitat were most strongly implicated in defining the suite of species present in the dams. Of the physical habitat parameters, sediment depth and canopy cover were most strongly linked with the observed macroinvertebrate communities.…”

“…As reported for farm ponds overseas, Australian farm dams can provide a variety of sustainable reservoirs of biodiversity in the landscape. The Raglan dams were found to have diverse macroinvertebrate assemblages with considerable variation among habitats within dams, and seasonally (Brainwood and Burgin 2006). These different assemblages were influenced by water quality, which was linked to land use and groundwater quality, with the water sources and relative impact of each varying among the three dams (Brainwood et al 2004).…”

“…The dams had different water sources (Brainwood et al 2004), and this was found to influence the macroinvertebrate communities present (Brainwood and Burgin 2006). Dam One was a raised tank, constructed in the 1960s to collect pasture runoff.…”

“…Each site was sampled using three basket-style artificial-substrate samplers (cf. Bennison et al 1989) with an in situ colonisation period of six weeks (Brainwood and Burgin 2006). Colonisation of artificial substrates is more rapid in summer than winter (Shaw and Minshall 1980), although a standard colonisation period has been recommended (Meier et al 1979), and the six-week period has been described as standard, practicable and adequate (Bennison et al 1989).…”