Climate Change and Shell-Boring Polychaetes (Annelida: Spionidae): Current State of Knowledge and the Need for More Experimental Research

Abstract

Anthropogenic climate change is considered to be one of the greatest threats facing marine biodiversity. The vast majority of experimental work investigating the effects of climate change stressors on marine organisms has focused on calcifying organisms, such as corals and molluscs, where cross-generational phenotypic changes can be easily quantified. Bivalves in particular have been the subject of numerous climate change studies, in part because of their economic value in the aquaculture industry and their important roles as ecosystem engineers. However, there has been little to no work investigating the effects of these stressors on the symbionts associated with these bivalves, specifically, their shell-boring polychaete parasites. This is important to understand because climate change may shift the synergistic relationship between parasite and host based on the individual responses of each. If such a shift favors proliferation of the polychaete, it may very well facilitate extinction of host bivalve populations. In this review I will (i) provide an overview of research completed thus far on the effects of climate change stressors on shell-boring polychaetes, (ii) discuss the technical challenges of studying these parasites in the laboratory, and (iii) propose a standardized framework for carrying out future in vitro and in vivo climate change experiments on shell-boring polychaetes.

Searching for a Home Port in a Polyvectic World: Molecular Analysis and Global Biogeography of the Marine Worm Polydora hoplura (Annelida: Spionidae)

“…Infestation of cultured oysters and especially abalone by P. hoplura has been a serious problem for aquaculture for a long time. Commercial interest stimulated studies on the morphology, genetic structure, reproductive biology and dispersal ability of this species [ 9 , 19 , 20 , 48 , 49 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. Some control of polychaete pests on cultured molluscs has been suggested [ 67 , 75 , 76 , 77 , 78 , 79 , 80 ], but the problem of infestation continues.…”

Worms on the Cape: an integrative survey of polydorid infestation in wild and cultivated oysters (Crassostrea virginica) from Massachusetts, USA

“…Goal two of this plan emphasizes sustainability which involves "advancing aquatic health management practices" along with understanding "climate change effects". Shell-boring polydorids pose a direct threat to the former while the latter may potentially interact with polydorid life history, resulting in a negative synergistic effect that greatly increases the risk of shellfish extirpation in the US (David, 2021). Unfortunately, attempts to completely eradicate polydorids from shellfish farms once they have been infested…”

“…Shell-boring polydorids are largely sessile and are dependent on their larvae for dispersal. Once the larvae are liberated from the female's egg string, they then settle on a calcareous substrate (e.g., an oyster), undergo metamorphosis and begin burrowing into the shell where they henceforth assume a sessile existence carrying out all of their essential biological activities, including reproduction and feeding (David, 2021). The burrowing activity of the worms weakens the oyster shell and forces the oyster to divert energy from growth to shell-repair resulting in smaller sizes at maturity and the emergence of unsightly blisters on the innermost layer of the shell, both of which directly impacts marketability of the crop and therefore profitability of the farm (Williams et al, 2016).…”

“…In fact, heavy infestation of polydorid worms have led to the closure of several shellfish farms around the world (Tan et al, 2023). In the United States, Polydora websteri has historically been recorded as the main culprit for shell infestations in commercial bivalves (Martinelli et al, 2020;David, 2021). However, in the last few years, two additional species -Polydora onagawensis and Polydora neocaeca have emerged as pathogens of eastern oysters and bay scallops, respectively, in the northeastern United States (Silverbrand et al, 2021;Davinack and Hill, 2022).…”

“…However, in the last few years, two additional species -Polydora onagawensis and Polydora neocaeca have emerged as pathogens of eastern oysters and bay scallops, respectively, in the northeastern United States (Silverbrand et al, 2021;Davinack and Hill, 2022). Coupled with climate change, these polychaete pests pose a serious threat to to shellfish stocks throughout the region (David, 2021).…”