Attached benthic Foraminifera as indicators of past and present distribution of the coral Primnoa resedaeformis on the Scotian Margin

Abstract

Benthic Foraminifera found attached to the deep-sea coral Primnoa resedaeformis may be used to establish paleo-coral locations long after the coral has disappeared. Recent coral research cruises have revealed that the coral on the Scotian Margin is in peril and in many cases no longer exists. Sea floor video footage suggests various fishing methods have destroyed much of the coral as it has in coastal areas off Norway and Alaska. To date deep-sea corals are sparse on the Scotian Margin; therefore evidence preserved in the sediment may establish whether corals were present and more abundant in the past. A representative assemblage of benthic foraminiferans found attached to the deep-sea coral Primnoa resedaeformis may be the evidence necessary to provide presence/absence indicators long after the coral has disappeared. Both foraminiferal species are known to be only associated with the coral, and distortion of the ventral side (attached) of common foraminiferal species found in the sediment, may provide a clue to past coral habitat. Identifying a deep-sea coral paleo-habitat indicator provides insight into the extent to which it existed. Video footage from coral cruises over the last three years indicates that coral and fish go hand in hand, an important observation for a region where fishing comprises 23 % of the local economy.

Twenty-eight foraminiferal species were found in a range of abundances on nine deep-sea coral specimens of Primnoa resedaeformis. Attached foraminiferans are found on the basal sections of the coral where they colonize onto the hard calcite substrate. One of the more common and consistent foraminiferal species found attached to the coral, Discanomalina semipunctata, is not found commonly on the continental margin in non-coral areas and may provide in situ evidence of past coral habitat.