Predation on Planted and Wild Bay Scallops (Argopecten Irradians Irradians) by Busyconine Whelks: Studies of Behavior Incorporating Acoustic Telemetry

Quantifying predator-prey interactions and gaining insights into predator behavior are crucial for optimizing restoration strategies; yet, such knowledge is often lacking for marine invertebrates. We examined potential impacts of predation by channeled (Busycotypus canaliculatus) and knobbed whelks (Busycon carica) on natural and planted populations of bay scallops in the Peconic Bays, New York, through laboratory and field investigations. Mean rates of predation by small channeled whelks were low: 0.06 and 0.005 scallops d-1 for adult and juvenile scallops; respective lab predation rates of small knobbed whelks on juvenile scallops were 24x higher. Channeled whelks usually did not damage shells of scallop prey (86%), but knobbed whelks typically notched the ventral shell margin (73%). In field plots where scallop densities were manipulated via removals/plantings, whelks consumed ~2% of ~19,100 planted juveniles; crabs and presumably finfish consumed over 40% in all trials overall. Acoustic telemetry revealed that tagged channeled whelks moved shorter distances and spent more time in plots planted with scallops versus those without scallops. Unexpectedly, whelks spent more time in low vs. high density plots, but consumed far more scallops in the latter. In trials without scallops, whelk movement rates were 5x higher, presumably due to increased exploratory behavior. Overall, whelks were most active during crepuscular hours and during periods of increasing wind speeds. Our results, combined with population abundance data, suggest that whelks (especially B. carica) are drawn to high density scallop plantings and may be important causes of bay scallop mortality in the context of restoration efforts.

Sourcing Busycon Artifacts of the Eastern United States

A review of the history of marine-shell chemical-sourcing efforts preceeds the introduction of this project. Atomic-absorption spectroscopy (AAS) was used to assay levels of Ca, Mg, Fe, and Sr, in 44 prehistoric Busycon carica and Busycon perversum specimens from the eastern United States. Control shells (35) were collected from food refuse in coastal archaeological sites from Long Island to the Mexico—United States border. Subject shells came from nine Archaic and Mississippian sites. Elemental ratios were clustered to derive a probable water-body origin for the nine artifacts. The influence of diagenesis, body part, and species was negligible, but geography heavily influenced the results. The three shells from Monks Mound indicated origin in tropical, eastern Gulf, and Atlantic water. The shells from the Indian Knoll, Mulberry, and Tatham sites appear to have originated in eastern Gulf waters. The shell from the Archaic-period Ward site seems to have come from tropical water.