Climate change may exacerbate the risk of invasiveness of non-native aquatic plants: the case of the Pannonian and Mediterranean regions of Croatia

Abstract

Non-native aquatic plants are amongst the major threats to freshwater biodiversity and climate change is expected to facilitate their further spread and invasiveness. To date, in Croatia, no complete list of non-native extant and horizon aquatic plants has been compiled nor has a risk screening been performed. To address this knowledge gap, 10 extant and 14 horizon aquatic plant species were screened for their risk of invasiveness in the Pannonian and Mediterranean regions of Croatia under current and predicted (future) climate conditions. Overall, 90% and 60% of the extant species were classified as high risk for the Pannonian and Mediterranean regions, respectively, under both climate scenarios. Of the horizon species, 42% were classified as high risk under current conditions and, under climate change, this proportion increased to 78%. The ‘top invasive’ species (i.e. scored as very high risk) under both climate conditions and for both regions were extant Elodea nuttallii and horizon Lemna aequinoctialis. The horizon Hygrophila polysperma was very high risk for the Mediterranean Region under current climate conditions and for both regions under projected climate conditions. Azolla filiculoides, Elodea canadensis, Egeria densa and Utricularia gibba were also classified as high risk under current climate conditions and, after accounting for climate change, they became of very high risk in both regions. Further, Gymnocoronis spilanthoides and Lemna minuta were found to pose a very high risk under climate change only for the Pannonian Region. It is anticipated that the outcomes of this study will contribute to knowledge of the invasiveness of aquatic plants in different climatic regions and enable prioritisation measures for their control/eradication.

Carnivorous plants and conservation – the role of carnivorous plant enthusiasts

“…Unfortunately, with ongoing global warming, more and more invasive exotic weeds are capable to establish and naturalize in areas where they were not able to survive previously (Hobbs 2000;Nobis et al 2009). Among these climate change winners are also some weedy CPs, e.g., Utricularia gibba, which was not hardy in many European climates, but which was recently found to survive and become an invasive species at very high risk in some countries due to global warming (Piria et al 2022).…”

Ecology of Elodea canadensis Michx. and Elodea nuttallii (Planch.) H. St. John—Insights from National Water Monitoring in Croatia

“…in Croatia was published by Rimac et al [ 22 ] updated by Vuković et al [ 23 ], who presented the results of extensive mapping, showing a large number of localities spread across a much wider area than first reported. Finally, Piria et al [ 24 ] classified E. nuttallii as very high risk and E. canadensis as high risk in terms of their invasiveness under current climate conditions in the Pannonian and Mediterranean regions of Croatia, as determined using risk-screening tools.…”