Population connectivity of the Olympia oyster in southern California

Abstract

The Olympia oyster is a useful model to study the population connectivity of estuarine invertebrates because it incorporates chemical information about the natal site into its shell before dispersal. This information can be accessed in recruits using laser ablation inductively coupled plasma mass spectrometry and compared with predispersal shells from possible source populations. Shelled Ostrea lurida larvae were periodically removed from adults at eight sites in four Southern California estuaries in the summers of 2006 and 2007. The ratios to calcium of copper, barium, lead, and uranium in the shells were used to distinguish among sites in linear discriminant function analyses. Jackknifed assignment accuracy by site was increased to 74% and 82% for 2006 and 2007, respectively, by grouping the eight sites into three regions. Settlement plates at each site in 2007 collected recent O. lurida recruits that were assigned to one of the three regions defined by the broods. San Diego Bay and the North County produced over 80% of the identifiable recruits in 2007, with Mission Bay producing the remaining minority. The majority of recruits to San Diego Bay were self‐recruits, whereas over half of the North County recruits were unidentifiable. Patterns of connectivity varied between recruitment pulses, but a substantial portion of larvae were exchanged among estuaries separated by as many as 75 km of coastline.