What is it about?
1. Introduction of alien species is one of the major threats to aquatic biota and knowledge of the major correlates of their occurrence is pivotal in planning reliable conservation strategies. 2. To understand whether specific freshwater habitats are more likely to be invaded than others, a dataset on the occurrence of 1604 species in 54 taxonomic groups from 181 sites across the Italian peninsula was gathered. 3. The EUNIS habitat classificationwas used, selecting for the study’s seven habitat types at the secondEUNIS level, including lentic (EUNIS C1; 64 sites), lotic (EUNIS C2; 99 sites) and highly artificial (EUNIS J5; 18 sites) habitats. 4. The aim of the study was to test whether the overall number of alien species and the proportion of alien species for each taxonomic group differed between habitat types and could be explained by environmental, human-mediated, or climatic factors. 5. Using generalized linear mixed effect models to account for potential confounding factors, only average air temperature of the site was a significant positive predictor of the occurrence of alien species, regardless of habitat type, species richness, and other climatic variables. 6. A direct effect of temperature could be excluded given the origin of alien species, mostly from colder areas than Italy. Thus, an indirect effect could be hypothesized at the Italian latitudes, with warmer areas potentially more likely to be visited by tourists than colder areas. If this hypothesis is confirmed, the results of the analyses call for a compromise between the maintenance of recreational activities in the wild and the preservation of a natural environment to prevent the arrival and spread of alien species. On the other hand, no further recommendations can be implemented regarding habitat susceptibility to alien species.
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Why is it important?
The results of the analysis of an extensive survey of freshwater biodiversity in continental Italy provide evidence for the differential susceptibility to invasion of different habitat types and provide a basis for setting conservation priorities, developing monitoring programmes and enforcing regulation.
Perspectives
1) It is pivotal to understand the large-scale mechanisms behind the occurrence of alien species, because more species have the probability of becoming invasive if more alien species are present, simply by chance, owing to numerical effects. 2) The strong influence of temperature on the occurrence of alien species confirms that biological invasions may be potentially controlled and limited only by mitigating human activities in the environment. 3) Conservation strategies for freshwater habitats in temperate areas such as Italy should focus on the warmest and most accessible sites, regardless of habitat type, to maximize their efficiency and efficacy. 4) Occurrence of alien species was similar in lentic and lotic habitats, thus their spread should be controlled with equal efforts in the two habitats, regardless of their different appeal for tourists and visitors.
Dr Angela Boggero
CNR-Water Research Institute
Read the Original
This page is a summary of: Weak effects of habitat type on susceptibility to invasive freshwater species: an Italian case study, Aquatic Conservation Marine and Freshwater Ecosystems, March 2014, Wiley,
DOI: 10.1002/aqc.2450.
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