SIGNIFICANCE OF ATLANTIC STURGEON FEEDING EXCAVATIONS, MARY'S POINT, BAY OF FUNDY, NEW BRUNSWICK, CANADA

• Published in: Palaios 2007-09, Vol.22 (5), p.457-464
• Main Authors: PEARSON, NADINE J, GINGRAS, MURRAY K, ARMITAGE, IAN A, PEMBERTON, S. GEORGE
• Format: Article
• Language: English
• Subjects: Acipenser; Acipenser oxyrhynchus; Acipenseridae; Actinopterygii; Albert County New Brunswick; Atlantic Ocean; Bay of Fundy; Canada; Chordata; coastal environment; Corophium volutator; deposition; Eastern Canada; erosion; Excavations; feeding; Foraging; ichnofossils; intertidal environment; Intertidal zones; Invertebrata; living taxa; Macoma balthica; Marine; Marine fishes; marine sediments; Maritime Provinces; Mary's Point; modern analogs; morphology; Mud flats; New Brunswick; North Atlantic; numerical models; Ocean tides; Osteichthyes; Paleontology; Pisces; Piscichnus; Population density; RESEARCH ARTICLE; Sediments; Sturgeon; Trace fossils; Vertebrata; vertebrate
• ISSN: 0883-1351; 1938-5323
• DOI: 10.2110/palo.2005.p05-121r

In this study we report on the occurrence and potential significance of Atlantic sturgeon (Acipenser oxyrhynchus) feeding traces observed in the Bay of Fundy in great abundance on the intertidal mud flats of Mary's Point, New Brunswick, Canada. The traces comprise a crescent-shaped impression and a plug-shaped excavation and are considered to be a modern analogue for the trace fossil Piscichnus. Local areas exhibit relatively great numbers of the feeding structure: the sediment in these zones contains bivalves (primarily Macoma balthica), worms (generally nereid polychaetes), and amphipods (Corophium volutator). Analysis of the feeding-trace distribution and orientation shows that activity is greatest within 500 m of mean high water and coincides with the highest population densities of amphipods (up to 30,000 individuals per m2). Where sturgeon feeding is most intense, voluminous quantities of clay and silt are redistributed. Within the study area, as much as 1,220 m3 of intertidal sediment is resuspended during the 6 summer weeks that mark peak sturgeon activity. The reworked sediment contributes to the extensive soupy substrate, which accumulates from suspension deposition of silts and minor amounts of clay during slack tide. Subsequent to their excavation, feeding depressions trap sediment. Thus, feeding by the Atlantic sturgeon locally represents an important erosional-depositional agent in the intertidal mud flat zone within Mary's Point.