Exploring larval phenology as predictor for range expansion in an invasive species

Luis Giménez,Ursula Ecker,Michael Exton,Simon Jungblut,Rebecca Meth,Steffen Harzsch,Gabriela Torres,Reinhard Saborowski,Franziska Spitzner

doi:10.1111/ecog.04725

Abstract

Predicting range expansion of invasive species is one of the key challenges in ecology. We modelled the phenological window for successful larval release and development (WLR) in order to predict poleward expansion of the invasive crab Hemigrapsus sanguineus along the Atlantic coast of North America and north Europe. WLR quantifies the number of opportunities (in days) when larval release leads to a successful completion of the larval phase; WLR depends on the effects of temperature on the duration of larval development and survival. Successful larval development is a necessary requirement for the establishment of self‐persistent local populations. WLR was computed from a mechanistic model, based on in situ temperature time series and a laboratory–calibrated curve predicting duration of larval development from temperature. As a validation step, we checked that model predictions of the time of larval settlement matched observations from the field for our local population (Helgoland, North Sea). We then applied our model to the North American shores because larvae from our European population showed, in the laboratory, similar responses to temperature to those of a North American population. WLR correctly predicted the northern distribution limit in North American shores, where the poleward expansion of H. sanguineus appear to have stalled (as of 2015). For north Europe, where H. sanguineus is a recent invader, WLR predicted ample room for poleward expansion towards NE England and S Norway. We also explored the importance of year‐to‐year variation in temperature for WLR and potential expansion: variations in WLR highlighted the role of heat waves as likely promoters of recruitment subsidising sink populations located at the distribution limits. Overall, phenological windows may be used as a part of a warning system enabling more targeted programs for monitoring.

Highlights

Widespread invasions as a consequence of human-mediated introduction of species (Gurevitch et al 2011) and climate change (García-Molinos et al 2016) are responsible for much of the current dynamics of natural communities
We focused on understanding the importance of spatial gradients in larval habitat quality, as a way to predict the establishment of self-sustained populations and the poleward expansion of the Asian shore crab Hemigrapsus sanguineus
We evaluated if the phenological window of larval release (WLR) would predict distribution limits and poleward expansion of the Asian shore crab Hemigrapsus sanguineus

Summary

Introduction

Widespread invasions as a consequence of human-mediated introduction of species (Gurevitch et al 2011) and climate change (García-Molinos et al 2016) are responsible for much of the current dynamics of natural communities. H. sanguineus develops through a pelagic larval phase of 3–5 weeks, characterised by several stages; the last stage, called megalopa, colonises (= settle on) rocky shore habitats and metamorphoses into a juvenile This crab has invaded the coast of North America and Europe (Dauvin et al 2009, Epifanio 2013). Lord and Williams (2017) reexamined the northern distribution limits in North America (in 2015) and concluded that the range expansion has stalled since 2005 Those field studies and additional laboratory experiments support the hypothesis that range limits depend on the tolerance of the larval stages to low (summer) temperature (lower limit 12–15°C: Epifanio et al 1998, Stephenson et al 2009).

Experiments

Results

Discussion

Data availability statement