Predicting the current and future global distribution of the invasive freshwater hydrozoan Craspedacusta sowerbii

Abstract

The freshwater jellyfish Craspedacusta sowerbii is one of the most widespread invasive species, but its global distribution remains uncertain due to ephemeral appearances and general lack of information in various aquatic environments. The aim of this study was to map current and future distributions (2050 and 2100) using Species Distribution Models allowing to visualize the habitat suitability and make projections of its changes under potential climate change scenarios. Except in Oceania where the range decreased, an expansion of C. sowerbii was projected during the next century under modeled future scenarios being most intensive during the first half of the century. The present study shows that the expansion of C. sowerbii worldwide would be facilitated mainly by precipitation, vapor pressure, and temperature. The predictions showed that this species over the eighty years will invade high-latitude regions in both hemispheres with ecological consequences in already threatened freshwater ecosystems.

Increasing Temperature Facilitates Polyp Spreading and Medusa Appearance of the Invasive Hydrozoan Craspedacusta sowerbii

“…Future scenarios provided larger optimal thermal areas for C. sowerbii , especially in the northern hemisphere, postulating a large range expansion. The generated monthly maps based on the species metabolism can be linked with the recent multiple factors correlative species distribution models that showed a poleward expansion of C. sowerbii by 2050 and 2100 [ 18 ]. During warmer months (35–42 °C), the medusa stage of C. sowerbii would be subjected to a "thermal stress state" with potentially significant effects on the reproduction and dispersal of the species, especially near the equator.…”

“…The invasive freshwater hydrozoan Craspedacusta sowerbii (Cnidaria, Hydrozoa, Olindiidae) is native to East Asia [ 15 , 16 ]. From the beginning of the 20th century, reports of C. sowerbii have been increasing globally [ 17 , 18 , 19 ]. Craspedacusta sowerbii has a metagenetic life cycle, in which asexually reproducing polyps and sexually reproducing medusae alternate [ 11 , 20 ].…”

“…Temperature plays a key role in driving biochemical reactions and metabolic processes in organisms determining thermal tolerance limits, phenology, and their ultimate distribution [ 1 , 23 , 24 , 25 ]. Despite its worldwide distribution, studies on the effects of environmental parameters on C. sowerbii polyp and medusa stages appear to be limited [ 26 , 27 , 28 ], but likely could be the key to understanding its invasive behavior [ 18 ]. Temperature and food availability have been identified as key parameters in the asexual and sexual reproduction success of C. sowerbii [ 27 , 29 ].…”

“…Temperature and food availability have been identified as key parameters in the asexual and sexual reproduction success of C. sowerbii [ 27 , 29 ]. A recent modeling study showed the importance of temperature on the current and future expansion of C. sowerbii [ 18 ]. There is little data on the thermal tolerance of both the polyp and medusa stages of C. sowerbii .…”

“…In the literature, a thermal optimum was identified for polyp budding between 12 and 20 °C [ 27 ], but knowledge of the effect of temperature on the fitness and structure of polyp colonies is currently missing. It appears necessary to explore the effect of temperature on polyps and medusae to predict the expansion potential of C. sowerbii in the near future to validate distribution models performed recently [ 18 ].…”