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.
For the study of genetic changes that occur over time in human communities (microevolution) anthropologists and biodemographers have favored the use of renewable flow, in particular the registers of marriage. Indeed they allow to easily estimate several biodemographic parameters (endogamy and exogamy; repeated pairs; immigration), even for long periods of time, since it is quite common to have consecutive series of documents relating to the marriage of a population. However, the sources of flow do not always allow to study in depth the factors that have given continuity to the community because they provide only partial information on demographic structure, the mode of aggregation of its members and the processes of change within families. A good alternative to sources of flow may be the use of sources of state, civil (censuses) or parish sources (the status animarum), which give a very detailed picture of the state of the population at a given time. The retrieval and analysis of census documentation assume therefore a primary role in order to obviate the intrinsic weaknesses of the sources of flow. In the perspective of biodemographic studies, the integration of the two types of sources is in actual fact the operating optimum. It must be remembered that it is quite difficult to find contemporary sources of flow and of state for the Italian populations of the past.
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