Effects of sediment deposition on the New Zealand cockle, Austrovenus stutchburyi

New Zealand estuaries and harbours are subjected to increasing sediment deposition that can smother and bury infaunal communities, yet how coastal species respond to sediment deposition is not well understood. Here, we experimentally examined the effects of native marine sediment deposition on the NZ cockle (Austrovenus stutchburyi). Cockles were found to be highly mobile and capable burrowers, able to resurface within days from beneath 2-25cm of sediment where no physical disturbance to their natural orientation occurred. Cockles were also resilient to daily (2cm) reburials. However, following disturbance to their natural orientation, inverted cockles were significantly impeded when buried under 5-10cm of sediment, with fewer adults resurfacing than sub-adults. Cockle populations are likely to be resilient to native sediment deposition, unless physically disturbed. When disturbed from their natural orientation in the sediment, higher mortality of larger adult-sized cockles would be predicted, with mortality increasing under thicker sediment deposits.