ABSTRACT

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."

This project concerns the ecological physiology of Dosidicus gigas, a large squid endemic to the eastern Pacific where it inhabits both open ocean and continental shelf environments. Questions to be addressed include: 1) How does utilization of the OML by D. gigas vary on both a daily and seasonal basis, and how do the vertical distributions of the OML and its associated fauna vary? 2)What behaviors of squid are impaired by conditions found in the OML, and how are impairments compensated to minimize costs of utilizing this environment? and 3)What are the physiological and biochemical processes by which squid maintain swimming activity at such remarkable levels under low oxygen conditions? The investigators will use an integrated approach involving oceanographic, acoustic, electronic tagging, physiological and biochemical methods. D. gigas provides a trophic connection between small, midwater organisms and top vertebrate predators, and daily vertical migrations between near-surface waters and a deep, low-oxygen environment (OML) characterize normal behavior of adult squid. Electronic tagging has shown that this squid can remain active for extended periods in the cold, hypoxic conditions of the upper OML. Laboratory studies have demonstrated suppression of aerobic metabolism during a cold, hypoxic challenge, but anaerobic metabolism does not appear to account for the level of activity maintained. Utilization of the OML in the wild may permit daytime foraging on midwater organisms. Foraging also occurs near the surface at night, and Dosidicus may thus be able to feed continuously. D. gigas is present in different regions of the Guaymas Basin on a predicable year-round basis, allowing changes in squid distribution to be related to changing oceanographic features on a variety time scales.

This research is of broad interest because Dosidicus gigas has substantially extended its range over the last decade, and foraging on commercially important finfish in invaded areas off California and Chile has been reported. In addition, the OML has expanded during the last several decades, mostly vertically by shoaling, including in the Gulf of Alaska, the Southern California Bight and several productive regions of tropical oceans, and a variety of ecological impacts will almost certainly accompany changes in the OML. Moreover, D. gigas currently supports the world's largest squid fishery, and this study will provide acoustic methods for reliable biomass estimates, with implications for fisheries management in Mexico and elsewhere. A related goal is to work with colleagues in Mexico on a squid fishery management plan. Previous work involved collaboration with Mexican colleagues, including training and research opportunities for undergraduate, graduate and postdoctoral students from both nations. It also involved public outreach efforts through television, print and web media. This charismatic species provides an excellent means to connect climate change with ecological effects, and outreach activities will continue with this theme. A new international effort will establish a laboratory for research on squid at the site of field work in Santa Rosalia, Baja California Sur, Mexico. The facility will involve Mexican college students in marine research and implement local educational programs.

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