Bioenergetics of the common seastar Asterias rubens: a keystone predator and pest for European bivalve culture

Abstract

Losses due to predation are recognized as an important factor affecting shellfish stocks, restoration efforts and aquaculture production. Managing and mitigating the impact of predators require information on the population dynamics and functional responses to prey availability under varying environmental conditions. Asterias spp. are well-known keystone predators with the capacity to exert a top down control on shellfish populations. Asterias spp. populations are extremely plastic, booming fast when prey is abundant and exhibiting a remarkable individual resilience to starvation and adverse environmental conditions. These aspects have led Asterias spp. to be considered pests by shellfish producers and fishers and to be catalogued among the most devastating invasive species. Assessment and mitigation of the impact of Asterias rubens in northern Europe have been the objective of several projects. However, there is still a limited understanding of the processes behind A. rubens population plasticity and how environmental conditions affect individual growth and predation. Under these circumstances a comprehensive eco-physiological model becomes necessary. These models can integrate available information on biology and eco-physiology to gain understanding of the effect of the environmental conditions on the impact of A. rubens.In this work, we performed a number of eco-physiological experiments and combined them with field data from a Danish estuary to estimate and validate the parameters of a dynamic energy budget (DEB) model for the whole life cycle of A. rubens. DEB models can be used to assess the effects of environmental variability on the life cycle and key population traits allowing the prediction of the performance, abundance, resource requirements and potential distribution of individuals and populations under dynamic environments. As such the DEB model presented in this study aims to become a tool to be used to assess and manage the impact of A. rubens in cultured and natural shellfish populations. The successfully parameterised DEB model describes A. rubens as a plastic species, an efficient predator with low maintenance costs and, at least while feeding on mussels, a high energy yield from its prey. The model validation against independent data resulted in the model being capable to assess growth, food demand, reproductive output and reserves dynamics of A. rubens under experimental and natural conditions. Moreover, application of the model to the Limfjorden seastar fishery is used to further discuss the use of the model to understand biology and ecology of this pest species in the context with the management of shellfish stocks and impact mitigation.

The relationship between size and metabolic rate of juvenile crown of thorns starfish

“…Population outbreaks of COTS are likely to be driven by their highly resilient and opportunistic nature (Deaker & Byrne, 2022), and their low metabolic rate is likely to contribute to this resilience. Sea stars and other echinoderms are known to have lower metabolic rates compared with other marine invertebrates (Agüera et al, 2021; Lawrence & Lane, 1982; Wilson et al, 2013). This may explain why both juvenile and adult COTS are able to withstand extended periods (months) of starvation (Caballes et al, 2016; Chesher, 1969; Yamaguchi, 1974b), which for adults can be as long as 10 months (Deaker pers.…”

Dislodgement and mortality challenges when restoring shallow mussel beds (Mytilus edulis) in a Danish estuary

“…Human top–down control of specific meso‐predators by concentrated fishing could be another possible approach. Strategic fishing of the predator A. rubens is already conducted in another Danish estuary, Limfjorden, to reduce predation pressure on mussel populations (Aguera et al 2021). To our knowledge, very little literature is available on this topic (Calderwood et al 2016; Aguera et al 2021) and further research is needed.…”

“…Strategic fishing of the predator A. rubens is already conducted in another Danish estuary, Limfjorden, to reduce predation pressure on mussel populations (Aguera et al 2021). To our knowledge, very little literature is available on this topic (Calderwood et al 2016; Aguera et al 2021) and further research is needed. Fundamentally, a broader ecosystem‐restoration approach could be required to help reduce trophic cascades and meso‐predator densities.…”

Elevated temperature linked to signs associated with sea star wasting disease in a keystone European species, Asterias rubens

“…The common starfish Asterias rubens is a highly abundant asteroid found on the Atlantic coast of Northwest Europe, inhabiting both sub-and intertidal zones (Saier 2001, Gallagher et al 2008, Agüera et al 2021. Sea stars in the genus Asterias are typical of many asteroids in that their role as keystone predators provides an important control on prey populations.…”