Upwelling winds off North Carolina set up upwelling fronts. As the wind forcing relaxed following such a coastal upwelling event, we observed the upwelling front move onshore. The low‐density surface water moved shoreward over the upwelled water, forming a convergence zone at the front. This shoreward‐moving front concentrated and transported larvae. Larval sergestid shrimp, spionid polychaete larvae, and the veligers of Odostomia sp. and Bittium sp. were concentrated on the seaward side of the moving convergence. Blue crab megalopae were concentrated at the surface immediately seaward of the front. These data demonstrate that a relaxing upwelling front can transport high concentrations of larvae shoreward over the inner shelf. This may be an important mechanism promoting the shoreward migration of larval invertebrates and fish.
Polychaete larvae from several families are thought to be natural predators upon planktonic bivalve larvae. However, little direct evidence of interactions between these predators and prey is available. We conducted predator-prey experiments on laboratory roller tables for five putative predatory polychaete larvae, representing four families (metatroch-less larvae of the Polynoidae and metatrochophore larvae of the Spionidae, the Magelonidae, and the Phyllodocidae). D-hinge veliger larvae of the oyster Crassostrea gigas were offered as prey. Predation was monitored over a range of prey densities and in the presence and absence of background plankton. "Background plankton" are any naturally occurring plankton assemblages found in whole, unfiltered seawater at ambient concentrations. For all polychaete larvae examined, when natural C. gigas densities and background plankton were used, no predation was observed. Magelonids and phyllodocids did not consume any C. gigas larvae, regardless of conditions. Polynoid and spionid trochophores consumed C. gigas veligers at both the "natural" and unnaturally high prey densities in filtered seawater. The addition of background plankton eliminated the predation at all natural prey densities and significantly reduced the predation observed at high prey densities.
P erhaps the largest-scale archaeological study ever undertaken in the Great Basin, the Ruby Pipeline Project included the investigation of 566 prehistoric sites across northern Nevada. A 13,000 year record of human occupation was documented spanning the first pluvial lake settlements at the close of the last Ice Age to the rise of the Western Shoshone and Northern Paiute. This archaeological record is replete with vast obsidian quarries, upland root-gathering sites, major residential bases, specialized hunting camps, and large-scale antelope traps. We are introduced to a prehistoric world of continual change, one marked by transformed environments, shifts in settlement and subsistence structure, and even wholesale population movements. The result is a work that allows us to chronicle the initial colonization of northern Nevada, monitor the subsequent process of population growth and dispersal, document the evolution of exchange systems, and propose a compelling new version of Numic prehistory.
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