Abstract
The toheroa (Paphies ventricosa) is an Aotearoa (New Zealand) endemic surf clam that remains threatened following population collapse due to overfishing in the twentieth century. Despite protective measures being in place for more than 4 decades, toheroa populations have inexplicably failed to recover. As part of an investigation into the possible role of disease in preventing their recovery, an exploration of the bacterial composition in toheroa was conducted over their entire geographic range. The bacterial composition in toheroa tissues was dominated by Spirochaetaceae, Mycoplasmataceae, and Endozoicomonadaceae, and varied at both large (between geographically separated sites) and small spatial scales (beds < 10 km apart). At small scales, it was habitat, in this case the presence or absence of freshwater outflows, which appeared to be a major influence on bacterial composition. Given that the decline of toheroa has also coincided with changes in land use that have reduced the amount of freshwater reaching the toheroa beaches, it is possible that habitat-related shifts in the abundance of certain bacterial symbionts are affecting the health and impeding recovery of this iconic and culturally significant species.
Highlights
The toheroa (Paphies ventricosa) is a large intertidal surf clam, typically found on exposed high-energy surf beaches
Bacteria regulate resistance to, and contribute to, disease (Bass et al 2019), and many biogeochemical cycles within host cells are driven by symbiotic bacteria (Neave et al 2016; Tandon et al 2020)
Bacteria contribute to host survival and homeostasis
Summary
The toheroa (Paphies ventricosa) is a large intertidal surf clam, typically found on exposed high-energy surf beaches. On many beaches where toheroa were once incredibly abundant, they are absent (Muriwai and Foxton), or populations are severely diminished (Ripiro and Te-Oneroa-a-Tōhē, see Fig. 1) (reviewed in Ross et al 2018a). Unsustainable harvesting practises (recreational and commercial) of the early twentieth century contributed to, or caused, the collapse of toheroa populations, but do not explain their failure to recover despite more than four decades of management and protection. Bacteria regulate resistance to, and contribute to, disease (Bass et al 2019), and many biogeochemical cycles within host cells are driven by symbiotic bacteria (Neave et al 2016; Tandon et al 2020). In this way, bacteria contribute to host survival and homeostasis. Bacteria are drivers and modulators of numerous metabolic processes within
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
