Biogeographical Patterns of Endolithic Infestation in an Invasive and an Indigenous Intertidal Marine Ecosystem Engineer

Abstract

By altering the phenotypic properties of their hosts, endolithic parasites can modulate the engineering processes of marine ecosystem engineers. Here, we assessed the biogeographical patterns of species assemblages, prevalence and impact of endolithic parasitism in two mussel species that act as important ecosystem engineers in the southern African intertidal habitat, Perna perna and Mytilus galloprovincialis. We conducted large-scale surveys across three biogeographic regions along the South African coast: the subtropical east coast, dominated by the indigenous mussel, P. perna, the warm temperate south coast, where this species coexists with the invasive Mediterranean mussel, M. galloprovincialis, and the cool temperate west coast dominated by M. galloprovincialis. Infestation increased with mussel size, and in the case of M. galloprovincialis we found a significantly higher infestation in the cool temperate bioregion than the warm temperate region. For P. perna, the prevalence of infestation was higher on the warm temperate than the subtropical region, though the difference was marginally non-significant. On the south coast, there was no significant difference in infestation prevalence between species. Endolith-induced mortality rates through shell collapse mirrored the patterns for prevalence. For P. perna, endolith species assemblages revealed clear grouping by bioregions. Our findings indicate that biogeography affects cyanobacteria species composition, but differences between biogeographic regions in their effects are driven by environmental conditions.

Foul‐weather friends: Modelling thermal stress mitigation by symbiotic endolithic microbes in a changing environment

“…Likewise, higher levels of shell corrosion at lower latitudes are unlikely due to latitudinal or geographical changes in endolithic species. Endolithic community composition does not differ significantly between M. galloprovincialis from native (Portugal) and invasive (South Africa) regions nor from P. perna shells from different bioregion along 1000s km of the South African coast (Marquet et al, 2013; Ndhlovu et al, 2019). Most importantly, our results indicate that endolithic corrosion is higher at lower latitudes where its beneficial effects are enhanced and most beneficial to the host.…”

“…In this context, mussel survival may increasingly benefit from the thermal buffering provided by endolithic shell erosion, which is predicted to increase as a result of ongoing ocean acidification and warming rates (Reyes‐Nivia et al, 2013; Tribollet et al, 2009). A further complication lies in the fact that the endoliths infesting mussel shells comprise a community, the composition of which alters in time and space (Ndhlovu et al, 2019; Pittera et al, 2014). Nevertheless, the generalist nature of endoliths and their ubiquitous erosion of marine calcifying organisms already stretched to the limits of their thermal tolerances strongly suggest that they will have a key influence on the ability of many intertidal ecosystems to maintain their ecological functions.…”

Global distribution and diversity of marine euendolithic cyanobacteria

“…Euendoliths are also important primary producers (Tribollet 2008) that contribute significantly to the cycling of nutrients, especially carbon and nitrogen, in nearshore marine waters (Tribollet et al 2006, Pfister et al 2010. Euendoliths bore into a wide range of substrata (Ram ırez-Reinat and Garcia-Pichel 2012a; Couradeau et al 2017), but are particularly efficacious in carbonate-containing rock and the calcium carbonate exoskeletons of organisms such as mollusks (Kaehler and McQuaid 1999, Ndhlovu et al 2019), crustacea, echinoderms, and corals (Campion-Alsumard and Hutchings 1995, Pernice et al 2020. The damage caused by euendoliths weakens the structural integrity of the substratum, which increases the costs of repair and maintenance for host organisms (Kaehler and McQuaid 1999, Day et al 2000, Zardi et al 2009, Curin et al 2014) and increases erosion rates of carbonate coastlines (Donn and Boardman 1988).…”

“…The euendolithic lifestyle is found across a wide range of organisms, including fungi, green and red algae, cyanobacteria, and sponges (Gektidis et al 2007, Cockell and Herrera 2008, Sch€ onberg and Wisshak 2012, Murphy et al 2016, Gleason et al 2017b). The cyanobacteria include numerous species of euendoliths such as Hormathonema sp., Hyella sp., Mastigocoleus testarum, and Plectonema terebrans, frequently occurring at high abundances on limpets, mussels, rocks, and experimental carbonate blocks (Gektidis et al 2007, Prusina et al 2015, Ndhlovu et al 2019. Their boring lifestyle may provide them with several ecological advantages including protection from environmental extremes, excessive ultraviolet light, abrasive detachment from substrata, grazing and predation, and increased access to nutrients (Guida et al 2017).…”

“…The greatest pH changes are expected in surface waters (Caldeira and Wickett 2003), putting shallow water and intertidal organisms, especially at risk. For example, euendolithic infestation can damage large proportions of populations of mollusks such as the mussels Mytilus galloprovincialis (Marquet et al 2013, Ndhlovu et al 2019 and Modiolus barbatus ( Curin et al 2014), and the limpet Patella rustica (Prusina et al 2015). In fact, euendoliths can be responsible for up to 60% of total mortality in mussel populations through shell collapse by bioerosion (Kaehler and McQuaid 1999, Zardi et al 2009, Ndhlovu et al 2019.…”