TY - JOUR
T1 - Subsurface recirculation and larval retention in the lee of a small headland
T2 - a variation on the upwelling shadow theme
AU - Roughan, Moninya
AU - Mace, Amber J.
AU - Largier, John L.
AU - Morgan, Steven G.
AU - Fisher, Jennifer L.
AU - Carter, Melissa L.
PY - 2005/10/8
Y1 - 2005/10/8
N2 - The interaction of alongshore coastal currents with large headlands has been shown to increase the retention of planktonic organisms through the formation of headland eddies or upwelling shadows in their lee. This study investigates the circulation within Bodega Bay (in the lee of a small headland), in an upwelling region, and the potential for retention of plankton. During the upwelling season of 2004, time series of temperature and velocity were recorded throughout Bodega Bay, conductivity-temperature-depth (CTD) surveys were conducted, and surface drifters were released during upwelling, downwelling, and relaxation conditions. Postlarval settlement was monitored daily over two periods coinciding with CTD surveys. Under strong upwelling favorable conditions, wind-driven surface currents were equatorward both offshore and throughout the bay. However, there was significant current shear along the eastern shore of the bay where cold bottom waters move poleward, counter to the direction of the wind-driven surface flow. During downwelling and relaxation conditions, flow was poleward throughout the water column along the eastern shore of the bay. Postlarvae settled during all wind conditions, but greatest settlement was observed at the onset of upwelling favorable conditions. While no "typical" upwelling shadow is evident in the lee of the Bodega headland, subsurface recirculation driven by the alongshore flow past Bodega Head may facilitate the retention of plankton in the bay. Previous studies have generally focused on large headlands; however, it is likely that other small embayments in the lee of small headlands may also provide retention opportunities for planktonic organisms in upwelling regions.
AB - The interaction of alongshore coastal currents with large headlands has been shown to increase the retention of planktonic organisms through the formation of headland eddies or upwelling shadows in their lee. This study investigates the circulation within Bodega Bay (in the lee of a small headland), in an upwelling region, and the potential for retention of plankton. During the upwelling season of 2004, time series of temperature and velocity were recorded throughout Bodega Bay, conductivity-temperature-depth (CTD) surveys were conducted, and surface drifters were released during upwelling, downwelling, and relaxation conditions. Postlarval settlement was monitored daily over two periods coinciding with CTD surveys. Under strong upwelling favorable conditions, wind-driven surface currents were equatorward both offshore and throughout the bay. However, there was significant current shear along the eastern shore of the bay where cold bottom waters move poleward, counter to the direction of the wind-driven surface flow. During downwelling and relaxation conditions, flow was poleward throughout the water column along the eastern shore of the bay. Postlarvae settled during all wind conditions, but greatest settlement was observed at the onset of upwelling favorable conditions. While no "typical" upwelling shadow is evident in the lee of the Bodega headland, subsurface recirculation driven by the alongshore flow past Bodega Head may facilitate the retention of plankton in the bay. Previous studies have generally focused on large headlands; however, it is likely that other small embayments in the lee of small headlands may also provide retention opportunities for planktonic organisms in upwelling regions.
KW - upwelling shadow
KW - larval retention
KW - Bodega Bay
KW - California
UR - http://www.scopus.com/inward/record.url?scp=28844503260&partnerID=8YFLogxK
U2 - 10.1029/2005JC002898
DO - 10.1029/2005JC002898
M3 - Article
AN - SCOPUS:28844503260
SN - 0148-0227
VL - 110
SP - 1
EP - 18
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
IS - 10
M1 - C10027
ER -