Current reversals as determinants of intertidal recruitment on the central Oregon coast

Abstract

Abstract Dudas, S. E., Grantham, B. A., Kirincich, A. R., Menge, B. A., Lubchenco, J., and Barth, J. A. 2009. Current reversals as determinants of intertidal recruitment on the central Oregon coast. – ICES Journal of Marine Science, 66: 396–407. The influence of current reversals on intertidal invertebrate recruitment was investigated using two seasons of nearshore physical and intertidal biological observations along the central Oregon coast, an intermittent upwelling system. In 1998, upwelling periods were punctuated by infrequent wind reversals and widespread increases in nearshore temperature, whereas 1999 was characterized by frequent, shorter wind reversals. In 1998, barnacle recruitment was best at the site experiencing more frequent reversals of the predominantly equatorward currents, higher poleward velocities, and coincident temperature increases. In 1999, barnacle recruitment peaked at the site with greater poleward current velocities, and maximum mussel recruitment at the site with consistent deep (10 m) onshore currents. Barnacle recruitment generally increased with onshore surface currents and temperature; mussel recruitment showed variable, weaker correlations. The data indicate that substantial decreases or complete reversals of upwelling-driven alongshore currents may be important for barnacle recruitment, but topographically driven differences in the response of currents to wind changes may generate local recruitment differences. This suggests that even relatively straight coastlines may have enhanced recruitment zones attributable to the variable local oceanography. Further, the interannual differences observed in current reversals and recruitment patterns highlight the potential importance of upwelling variation for onshore communities.