Synchronous settlement of barnacle larvae at small spatial scales correlates with both internal waves and onshore surface winds

Delivery of zooplankton to the surf zone during strong internal tidal forcing and onshore winds in Baja California

“…In the present study, an interaction between onshore winds and internal waves was found for gastropods and foraminifera for the first time in this area. Previous studies collected meroplankton in the water column far from the surf zone or entailed intertidal settlement surveys at a daily frequency (Ladah et al 2005, Liévana MacTavish et al 2016, Valencia-Gasti & Ladah 2016, which may be the reason the combination of mechanisms had not been detected. In the present study, we may have been able to identify both mechanisms as important due to the high frequency of sampling and the proximity to the shore, as this was the first time the abundance of zooplankton in the surf zone was determined at an hourly scale at the Bay of Todos Santos.…”

“…Changes in abundance and vertical distribution of plankton across the shelf have been well documented (Ladah et al 2005, Shanks 2006, Liévana Mactavish et al 2016, Valencia-Gasti & Ladah 2016; however, there is limited information on the delivery of larvae to and in the surf zone, especially at reflective shores. In situ sampling and numerical simulations of larval transport have been performed to better understand the process (Fujimura et al 2014, Morgan et al 2017), yet much is still unknown.…”

“…Liévana MacTavish et al (2016) showed significant changes in the vertical distribution and abundance of barnacle and crabs in the water column across internal tidal fronts, and internal tidal bores have been associated with settlement of the barnacle Chthamalus spp. in the intertidal zone (Ladah et al 2005, Valencia-Gasti & Ladah 2016. Internal tidal bores occur on every continental shelf (Shanks 1995, Leichter et al 2005, and because they may be critical for cross-shelf and surf zone transport of many marine larvae, exploring their ability to deliver plankton to nearshore waters is necessary for understanding the dynamics of coastal populations (Franks 1997, Helfrich & Pineda 2003, particularly on less-studied reflective beaches.…”