From wind to whales: trophic links in a coastal upwelling system

Abstract

Blue whales Balaenoptera musculus meet the highest prey demands of any predator that has ever existed by feeding exclusively upon dense but patchy schools of pelagic euphausiids. We examined the role that seasonally high primary production supported by coastal upwelling combined with topographic breaks off California play in creating, collecting, and maintaining euphausiids at densities sufficient to allow exploitation by whales. We used concurrent ship-and mooringbased oceanographic, hydroacoustic, and net sampling, whale-sighting records, visual surveys, and time-depth recorder deployment to examine temporal and spatial linkages between (1) intensity of upwelling, (2) primary production, (3) development, density and distribution of euphausiids, and (4) the distribution, abundance, and foraging behavior of blue whales in Monterey Bay, California between 1992 and 1996. Blue whales fed exclusively upon adult euphausiids Thysanoessa spinifera and Euphausia pacifica that were larger than those generally available in the Bay. ) and a submarine canyon that provides deep water down-current from an upwelling region. Peak euphausiid densities occur in late summer/early fall, lagging the seasonal increase in primary production by 3 to 4 mo. This lag results from the temporal development of euphausiids spawned around the spring increase in primary production and the shoreward collapse of productivity due to decreased upwelling in late summer. The migratory movements of the California blue whale probably reflect seasonal patterns in productivity in other foraging areas similar to those we describe for Monterey Bay.

Projecting Marine Mammal Distribution in a Changing Climate

“…While progress has been made in projecting large-scale prey resource changes (e.g., Stock et al, 2014;Lefort et al, 2015), marine mammal species such as blue whales (Balaenoptera musculus) show tight coupling to smaller scale oceanographic features (Fiedler et al, 1998;Moore et al, 2002;Croll et al, 2005) associated with high euphausiid (krill) abundance (Santora et al, 2011). Similar relations have been exhibited by bowhead whales (Balaena mysticetus) across the Arctic (Laidre et al, 2007;Citta et al, 2015;George et al, 2015) and North Atlantic right whales (Baumgartner et al, 2003;Baumgartner and Mate, 2005).…”

A dated molecular phylogeny of manta and devil rays (Mobulidae) based on mitogenome and nuclear sequences

“…Although upwelling is not the only source of high productivity in the ocean, it does concentrate resources in a relatively small geographic area, often providing densities of food particles high enough to meet the large energy demands of filterfeeding marine mega fauna (Croll et al, 2005). This is evident today, as contemporary mobulid distributions largely overlap with areas of high upwelling-related productivity in tropical and subtropical oceans (Fig.…”

Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey

“…For large baleen whales spending the summer months in the Southern Ocean, these parameters most likely serve as proxies for prey distribution, since feeding is the main reason for these species to perform seasonal migrations to Antarctic waters. Prey is thus likely to be a main driver of their distribution (Croll et al 2005;Friedlaender et al 2006). In the Southern Ocean, several euphausiid species, collectively referred to as 'krill', are the major prey resource for baleen whales (Steele 1970;Knox 2007;Nicol et al 2008).…”