Range extension of a euryhaline crab, Varuna litterata (Fabricius, 1798) (Brachyura: Varunidae), in a climate change hot-spot

Abstract

We present the first recorded range extension of a euryhaline invertebrate in the climate change hot-spot along Australia's southeastern coast. The river swimming Crab, Varuna litterata (Fabricius, 1798) (Varunidae) was found in the Coffs Harbour-Bellinger and Nambucca river basins of New South Wales, Australia in 2013, 2014 and 2016. The crabs were found during winter in shallow freshwater habitats, and may be using these habitats to avoid predators or minimise exposure to colder temperatures in deeper water. At locations where the crabs were found, water temperatures during winter (July 2016) were up to 4.5 °C warmer in shallow-water habitats (< 0.2 m depth) compared to adjacent deep-water habitats (> 1.0 m). The new southernmost locations of V. litterata reported here represent a ~290 km poleward range extension. The likelihood that climate change and a strengthening East Australian Current have contributed to this range extension is discussed, as well as the potential impacts of these crabs on existing biological communities in newly colonised locations.

Spatial distribution management of Crustacea (Decapoda) based on conservation in tropical tidal lake

“…Lapolo et al (2018) only were found in mangrove area at Tanjung Panjang Nature Reserve in Gorontalo. According to Lapolo et al (2018), V. yui is mostly found in pond areas, while V. litterata is found in freshwaters and the sea during reproduction (Mos et al 2017;Lapolo et al 2018;Susilo et al 2020). Furthermore, Carpenter and Niem (1998) stated that V. yui is a rare crab where adults are usually found in the open sea while juveniles are found in sluice gates or water embankments in mangrove areas close to land.…”

Range expansion of a widespread Indo‐Pacific haemulid, the barred javelin Pomadasys kaakan (Cuvier, 1830), in a climate change hotspot

“…This study adds to a growing list of species recorded moving south in this region ( e.g . Mos et al , 2017; Robinson et al , 2015). It is possible that warm, shallow habitats within the estuary have helped P. kaakan to overwinter in the Nambucca River at the southernmost extent of its newly expanded range, similar to the way in which the river swimming crab, Varuna litterata (Fabricius, 1798) is thought to survive in the same estuary (Mos et al , 2017).…”

“…Mos et al , 2017; Robinson et al , 2015). It is possible that warm, shallow habitats within the estuary have helped P. kaakan to overwinter in the Nambucca River at the southernmost extent of its newly expanded range, similar to the way in which the river swimming crab, Varuna litterata (Fabricius, 1798) is thought to survive in the same estuary (Mos et al , 2017). Estuaries in Australia's south‐east are warming at twice the rate of the ocean or atmosphere (Scanes et al , 2020), which highlights the potential for these waterways to play an important role in facilitating the poleward movement of tropical species in the region.…”