Physical-biological coupling in Monterey Bay, California: topographic influences on phytoplankton ecology

Abstract

Physical-biological couplings impacting phytoplankton ecology are examined with synoptic, high-resolution observations of Monterey Bay, California. Influences of submarine canyon and shelf break topography on the physical-biological couplings are supported by 2 case studies. In the first case study, benthic-pelagic coupling was observed in southern shelf waters where a turbid plume extended from the bottom at ~60 m deep to the base of a phytoplankton layer centered at ~10 m deep. The alongshelf scale of the plume ranged from ~5 km near the bottom to ~1 km at its intersection with the phytoplankton layer. In situ and remote sensing data support the influence of Monterey Canyon on circulation forcing the benthic-pelagic coupling. In the second case study, a frontal zone and adjacent waters were rapidly surveyed over ~20 km 2 of the northern shelf. The front was associated with an isopycnal ridge/trough structure, surface slick, and frontal eddy <1 km in diameter. The magnitude and vertical location of a chlorophyll maximum layer were closely coupled with the physical environment through the frontal zone. The layer was dispersed by the isopycnal ridge and frontal eddy, and concentrated in the isopycnal trough and along the periphery of the eddy. Influence of an internal wave generated by interaction of tidal currents with the shelf break is supported by the observed surface slick, measured water velocities, and the proximity and orientation of the shelf break. Significant and persistent influences of topography on phytoplankton ecology in Monterey Bay are indicated.

Ecological Role of Submarine Canyons and Need for Canyon Conservation: A Review

“…For example, currents funneled through canyons likely enhance primary productivity (Ryan et al, 2005) and drive sediment transport and associated particle-reactive substances toward deep environments . Higher levels of primary productivity may lead to canyons being hotspots of faunal productivity in the deep sea .…”

“…The adjustments of the current to the canyon topography produce vortex stretching and vertical motions (Klinck, 1996;Hickey, 1997). These modifications of the currents may result in local upwelling, which pumps nutrients to the euphotic zone and thus stimulates primary production (Ryan et al, 2005). Additionally, closedcirculation cells and downwelling may develop over canyons, enhancing the capacity of the canyon to trap particles transported by long-shore currents (Granata et al, 1999;Palanques et al, 2005;Allen and Durrieu de Madron, 2009).…”

Mobile autonomous process sampling within coastal ocean observing systems

“…3 indicate where chlorophyll fluorescence intensity was above the level at which bio-optical signal can be clearly distinguished from random noise in the chlorophyll fluorescence data. (Ryan et al 2005). Vertical transport into the mixed layer in this way would also strongly influence the dynamical and biological exposure of larvae transported with an INL.…”

Effect of continental shelf canyons on phytoplankton biomass and community composition along the western Antarctic Peninsula

“…Allen et al 2001, Ryan et al 2005 and subsequent distribution and diversity of higher trophic levels (Cunha et al 2011, Fanelli et al 2011. Canyon dynamics along some regions of the Antarctic continental margin may be affected both by latitudinal trends in atmospheric warming and sea ice loss, as well as regional shifts in winds and ocean circulation.…”