Monitoring Freshwater Macroinvertebrates
That invertebrate assemblages and individual species respond, often in predictable ways, to numerous changes their environments, gives them enormous value in assessing and predicting changes in water quality, impacts of disturbances, and the resources nee
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Monitoring Freshwater Macroinvertebrates
4.1 Scope and Needs for Assessments That invertebrate assemblages and individual species respond, often in predictable ways, to numerous changes their environments, gives them enormous value in assessing and predicting changes in water quality, impacts of disturbances, and the resources needed to sustain diversity and functions. However, detecting those changes in species incidence, richness and community composition and defining their causes is rarely easy—not least because many of the causes may not be evident, or interact in unexpected or undetected ways. The foundations discussed by Vinson and Hawkins (1998, based on ecological principles elucidated earlier by Thienemann) underpin much later discussion. Those principles are (1) richness increases with increased diversity of conditions, as ‘heterogeneity’; (2) the more that conditions change, or are changed, from the normal range to which most resident species are suited, the smaller the number of those species that occur there and the greater the abundance of those species that do occur; and (3) the longer the water body remains in the same condition, the richer and more stable its biotic community will become. Applied initially to stream insects, the patterns suggested have been investigated extensively to reveal considerable variety, in part reflecting scale of consideration— from individual water bodies to catchment or regional studies. However, as affirmed by Stendera et al. (2012), the study of those effects itself has many restrictions—not least of cost and available experience—but also because the four main categories of ‘stressors’ to freshwater ecosysystems commonly act simultaneously and with varied additive, antagonistic or synergistic effects. Those categories were recognised by Vorosmarty et al. (2010) as catchment disturbance (such as land use or deforestation), pollution, water resource development (such as alteration of natural flow regimes), and biotic factors (such as invasive species), all of which have potential to become ‘threats’ to biodiversity (Chap. 6) either individually or in concert. In general, stressors tend to cause declines in species richness and diversity. As predominant, universal, easily sampled, ecologically diverse and taxonomically rich components of inland water communities, insects and their relatives © Springer Nature Switzerland AG 2020 T. R. New, Insect Conservation and Australia’s Inland Waters, https://doi.org/10.1007/978-3-030-57008-8_4
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4 Monitoring Freshwater Macroinvertebrates
have formed the bases of numerous ‘indices’ and allied metrics to measure and compare condition, conservation status and needs of water bodies over space and time, and to define targets for management and monitor trajectories toward those goals. Benthic macroinvertebrates have played major roles in the development of freshwater monitoring, and the changes that occur from both natural processes and human interventions. Indeed ‘Aquatic insects and other benthic macroinvertebrates are the mo
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