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

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.

Potential impact of climate-related changes is buffered by differential responses to recruitment and interactions

“…Although mussel recruitment was responsive to large, basin-scale, climatic fluctuations (NPGO; Menge et al 2009), identifying the exact processes that drive local-scale barnacle recruitment awaits further analysis. These processes are currently under debate, and will likely include upwelling and other more local-scale variables, including internal waves, tidal change, larval behavior, and processes leading to retention of larvae close to shore (e.g., Dudas et al 2009, Pineda et al 2009, Shanks 2009). Overall, the implication is that the dynamics of rocky intertidal communities exhibit nonlinear, speciesspecific responses to both ocean-scale and local-scale physical and biological factors.…”

“…This analysis also means that about 60% of the variance is unexplained, and most likely is explained by smaller, regional-to local-scale factors such as coastal currents, bottom and coastal topography, larval behavior, sea breezes, fronts between water masses, tidal change, waves, and upwelling (e.g., Farrell et al 1991, Pineda 1991, Shanks and Brink 2005, Woodson et al 2007, Rilov et al 2008, Dudas et al 2009, Morgan et al 2009). Differential responses to these various smallerscale factors is the likely explanation underlying the divergent patterns of recruitment in space and time seen in mussels and barnacles along the Oregon coast (e.g., Menge et al 2009Menge et al , 2011Figs.…”

Influence of intermittent-upwelling on Mytilus galloprovincialis settlement patterns in the Ría de Ares-Betanzos

“…Recent works pointed out the relevance of frequency and variability of upwelling episodes in recruitment dynamics of diverse invertebrate species (Guisande et al 2001, Otero et al 2008, Pfaff et al 2011). In addition, several studies have shown lower recruitment rates in areas with persistent downwelling (Menge et al 2003) or upwelling conditions (Navarrete et al 2005, Broitman et al 2008, Dudas et al 2009b) compared to geographical areas characterized by intermittent upwelling.…”

Variation in recruitment rates of rocky shore intertidal invertebrates in response to alterations in physical forcings, chlorophyll-a concentration and temperature: the effect of cold fronts

“…In upwelling systems, mussel recruitment is associated with variability in adult abundance and fluctuations in primary productivity, upwelling intensity, and coastal currents (e.g. PORRI et al, 2006;DUDAS et al, 2009;REAUGH-FLOWER et al, 2011;but see BROITMAN et al, 2005). The wide range of variables covered in this study and the spatio-temporal resolution provided detailed information about the pelagic conditions, hence increasing the probability of finding significant relationship, even with very low recruitment.…”

“…Barnacles and mussels are important components of intertidal communities and are frequently used as model organisms in recruitment studies. However, they respond differently to variations in the pelagic environment, such as changes in SST (DUDAS et al, 2009;ILES et al, 2012). Differences in larval behavior (SHANKS & BRINK, 2005) and in tolerance of recruits to environmental stress (WETHEY et al, 2011) can also explain recruitment variation between barnacles and mussels.…”