Boring bivalves are well known to establish complex relationships with scleractinian corals, but their association with cirratulids has not received attention. Here, we report on dm-sized bioconstructions formed by aggregated tubes of Cirratulidae worms (Dodecaceria fistulicola and Dodecaceria sp.) from Lower Pleistocene (Màncora Tablazo) and Recent (Paracas, Laguna Grande) coastal areas in Peru that are heavily bored by the mytilid bivalve Leiosolenus peruvianus. Further findings from southern coasts up to Chile are to be studied. Dodecaceria forms reef-like aggregations, shaped as small heads, typically in shallow-water settings. The tube wall of this worm consists of micritic peloidal lamellae that form a stromatolitic fabric with intercalated calcite/aragonite crystals. Leiosolenus is known to bore in rocks and coral reefs, but its distributions and substrate habits are not clear to date. Peruvian finds represent the first documentation of cirratulid reefs bored by bivalves. Several generations of borers grow in different directions. Colonization takes place post-mortem but also in vivo as indicated by worm tubes growing around some bivalve perforations. Whether the colonizing organisms established a commensal or mutualistic relationships with the cirratulids is still to be investigated. The infesting bivalve L. peruvianus can get several advantages from living in a cirratulid reef, including the accretion in this living substrate (also allowing minimal space competition) rather than wearing out by (bio)erosion. Advantages can be also postulated for the cirratulid hosts that could benefit from the microcirculation induced by the large bivalves as well as from the nutrients provided by the decaying tissues of dead specimens. As both L. peruvianus and the studied forms of Dodecaceria are provided with mineralised skeletons, details of their interaction are easily preserved in the fossil record, and this is of paramount relevance for palaeobiological studies.
Boring bivalves and their host cirratulid reefs: fossil and modern records from coastal Peru
Giulia BOSIO;Alberto COLLARETA;
2022-01-01
Abstract
Boring bivalves are well known to establish complex relationships with scleractinian corals, but their association with cirratulids has not received attention. Here, we report on dm-sized bioconstructions formed by aggregated tubes of Cirratulidae worms (Dodecaceria fistulicola and Dodecaceria sp.) from Lower Pleistocene (Màncora Tablazo) and Recent (Paracas, Laguna Grande) coastal areas in Peru that are heavily bored by the mytilid bivalve Leiosolenus peruvianus. Further findings from southern coasts up to Chile are to be studied. Dodecaceria forms reef-like aggregations, shaped as small heads, typically in shallow-water settings. The tube wall of this worm consists of micritic peloidal lamellae that form a stromatolitic fabric with intercalated calcite/aragonite crystals. Leiosolenus is known to bore in rocks and coral reefs, but its distributions and substrate habits are not clear to date. Peruvian finds represent the first documentation of cirratulid reefs bored by bivalves. Several generations of borers grow in different directions. Colonization takes place post-mortem but also in vivo as indicated by worm tubes growing around some bivalve perforations. Whether the colonizing organisms established a commensal or mutualistic relationships with the cirratulids is still to be investigated. The infesting bivalve L. peruvianus can get several advantages from living in a cirratulid reef, including the accretion in this living substrate (also allowing minimal space competition) rather than wearing out by (bio)erosion. Advantages can be also postulated for the cirratulid hosts that could benefit from the microcirculation induced by the large bivalves as well as from the nutrients provided by the decaying tissues of dead specimens. As both L. peruvianus and the studied forms of Dodecaceria are provided with mineralised skeletons, details of their interaction are easily preserved in the fossil record, and this is of paramount relevance for palaeobiological studies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
