Facilitating foundation species: The potential for plant–bivalve interactions to improve habitat restoration success

Abstract

Vegetated marine and freshwater habitats are being increasingly lost around the world. Habitat restoration is a critical step for conserving these valuable habitats, but new approaches are needed to increase restoration success and ensure their survival. We investigated interactions between plants and bivalves through a review and analysis of 491 studies, determined the effects, mechanisms and key environmental variables involved in and driving positive and negative interactions, and produced guidelines for integrating positive interactions into restoration efforts in different habitats. Fifty per cent of all interactions (both correlative and experimental studies) were positive. These were predominant between epifaunal bivalves and plants in all habitats, and between infaunal bivalves and plants in subtidal habitats. Plants primarily promoted bivalve survival and abundance by providing substrate and shelter, while bivalves promoted plant growth and survival by stabilizing and fertilizing the sediment, and reducing water turbidity. The prevalence of positive interactions increased with water temperature in subtidal habitats, but decreased with water temperature in intertidal habitats. The subset of studies conducted in a restoration context also showed mostly positive interactions. Twenty‐five per cent of all interactions were negative, and these were predominant between plants and infaunal bivalves in intertidal habitats, except sulphide‐metabolizing bivalves, which facilitated plant survival. Interactions involving non‐native species were also mostly negative. Synthesis and applications. Promoting facilitative interactions through plant–bivalve co‐restoration can increase restoration success. The prevalence of positive interactions depends on habitat and environmental conditions such as temperature, and was especially important in subtidal habitats (involving both infaunal and epifaunal bivalves) and in intertidal habitats (involving only epifaunal bivalves). Thus sites and species for co‐restoration must be carefully chosen to maximize the chances of success. If done properly, co‐restoration could increase initial survival, persistence and resilience of foundation species, and promote the recovery of associated biodiversity and ecosystem services.

Historical Analysis Exposes Catastrophic Seagrass Loss for the United Kingdom

“…In addition to industrial development, the scale of overfishing of oysters around the United Kingdom cannot be ignored as a fundamental change and major disturbance to the environmental conditions. There is growing evidence of the close positive interactions that occur between seagrasses and many bivalves ( Perkins, 1988 ; Gagnon et al, 2020 ). Locations such as the Firth of Forth have entirely lost up to 5,000 ha of oyster beds ( Thurstan et al, 2013 ).…”

Reciprocal facilitation between annual plants and burrowing crabs: Implications for the restoration of degraded saltmarshes

“…Many studies have shown that promoting facilitative interactions between important species can increase the success of the ecosystem restoration (Derksen‐Hooijberg et al., 2017; Gagnon et al., 2020). Our results suggested a reciprocal facilitation between annual saltmarsh plants and burrowing crabs in the middle‐elevation saltmarshes of the Yellow River Delta, that the crabs facilitated plant seed retention and seedling establishment in winter and spring by modifying the sediment microtopography and the plants facilitated the crabs by providing protection from predators, providing food and reducing physical stresses in summer and autumn.…”

Facultative mutualisms: A double‐edged sword for foundation species in the face of anthropogenic global change

“…In the context of restoration or habitat creation efforts, our findings suggest that harnessing self‐facilitation and mutualisms can enhance the success of such interventions to regain foundation species and their ecological benefits (Gagnon et al., 2020; Valdez et al., 2020). Indeed, recent experimental work in salt marshes highlights that including self‐facilitation into restoration designs by clumping cordgrass transplants rather than planting them in dispersed arrays can double restoration yields (Silliman et al., 2015).…”