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Shipworms are a group of wood-boring and wood-feeding bivalves of extraordinary economic, ecological and historical importance. Known in the literature since the fourth century BC, shipworms are both destructive pests and critical providers of ecosystem services. All previously described shipworms are obligate wood-borers, completing all or part of their life cycle in wood and most are thought to use wood as a primary source of nutrition. Here, we report and describe a new anatomically and morphologically divergent species of shipworm that bores in carbonate limestone rather than in woody substrates and lacks adaptations associated with wood-boring and wood digestion. The species is highly unusual in that it bores by ingesting rock and is among the very few known freshwater rock-boring macrobioeroders. The calcareous burrow linings of this species resemble fossil borings normally associated with bivalve bioerosion of wood substrates (ichnospecies Teredolites longissimus) in marginal and fully marine settings. The occurrence of this newly recognized shipworm in a lithic substrate has implications for teredinid phylogeny and evolution, and interpreting palaeoenvironmental conditions based on fossil bioerosion features. [ABSTRACT FROM AUTHOR]

Ecosystem engineers can modulate harsh abiotic conditions, thus creating habitat for species that cannot withstand the local environment. In this study, we investigated if vacant boreholes created by the rock-boring bivalve Petricola dactylus increase species richness in the low intertidal zone of a Patagonian rocky shore characterized by intense hydrodynamic forcing and sediment scour. Invertebrate species richness was three times higher in engineered than unengineered habitats (i.e., with and without Petricola boreholes, respectively) and the increase in species richness was area-independent. The most prevalent species in unengineered areas showed strong adhesion mechanisms, whereas infaunal and vagile species were mostly restricted to boreholes. The positive influence of engineered microhabitats on species richness can largely be attributed to amelioration of physical conditions, particularly a reduction in hydrodynamic forces and sediment trapping/stabilization within boreholes. We conclude that vacant boreholes are essential microhabitats for the maintenance of biodiversity within the otherwise inhospitable low intertidal zone.

Abstract: The boring bivalve Lithophaga patagonica (d'Orbigny, 1842) is a locally abundant inhabitant of hard substrata in the coastal waters of the Southwestern Atlantic. In this paper, we describe the growth, age and mortality of three intertidal rock-boring populations of L. patagonica and one subtidal oyster shell (Ostrea puelchana) boring population. An analysis of acetate peel replicas of shell sections showed that L. patagonica slows down its growth during autumn–winter, which leads to changes in the direction and rate of shell deposition and the formation of conspicuous annual (low temperature induced) clefts in the shell margin. Cleft counts and Von Bertalanffy growth analyses indicated that maximum age varies from 4years in the oyster-boring population to 13years in a rock-boring one (longevity estimates varied between 6.5 and 15years, respectively). Maximum asymptotic length (L∞) and Von Bertalanffy growth constant (K) were also variable between populations (L∞ between 14.76 and 36.95mm and K from 0.20 to 0.90yr−1 respectively). Mortality rates were higher at the two southernmost populations. Type (rock vs. oyster), composition and hardness of the substrata are likely the main factors controlling the observed differences between populations. [Copyright &y& Elsevier]

Ecosystem engineers can modulate harsh abiotic conditions, thus creating habitat for species that cannot withstand the local environment. In this study, we investigated if vacant boreholes created by the rock-boring bivalve Petricola dactylus increase species richness in the low intertidal zone of a Patagonian rocky shore characterized by intense hydrodynamic forcing and sediment scour. Invertebrate species richness was three times higher in engineered than unengineered habitats (i.e., with and without Petricola boreholes, respectively) and the increase in species richness was area-independent. The most prevalent species in unengineered areas showed strong adhesion mechanisms, whereas infaunal and vagile species were mostly restricted to boreholes. The positive influence of engineered microhabitats on species richness can largely be attributed to amelioration of physical conditions, particularly a reduction in hydrodynamic forces and sediment trapping/stabilization within boreholes. We conclude that vacant boreholes are essential microhabitats for the maintenance of biodiversity within the otherwise inhospitable low intertidal zone. [ABSTRACT FROM AUTHOR]