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Marine Ecology Progress Series

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MEPS 226:235-247 (2002)  -  doi:10.3354/meps226235

Distribution of the euryhaline squid Lolliguncula brevis in Chesapeake Bay: effects of selected abiotic factors

I. K. Bartol1,*, R. Mann2, M. Vecchione3

1Department of Organismic Biology, Ecology, and Evolution, University of California, Los Angeles, 621 Charles E. Young Drive South, Los Angeles, California 90095-1606, USA
2School of Marine Science, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA
3National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Systematics Laboratory, National Museum of Natural History, 10th and Constitution NW, Washington, DC 20560, USA

ABSTRACT: The majority of cephalopods are thought to have limitations arising from physiology and locomotion that exclude them from shallow, highly variable, euryhaline environments. The brief squid Lolliguncula brevis may be a notable exception because it tolerates low salinities, withstands a wide range of environmental conditions, and swims readily in shallow water. Little is known about the distribution of L. brevis in Chesapeake Bay, a diverse and highly variable estuary. Therefore, a survey of L. brevis was conducted in the Virginia portion of Chesapeake Bay from 1993 to 1997 using a 9.1 m otter trawl, and the effects of selected factors on squid presence were assessed using logistic regression analysis. During spring through fall, L. brevis was collected over a wide range of bottom-water salinities (17.9 to 35.0 ‰), bottom-water temperatures (8.1 to 29.6°C), bottom-water dissolved oxygen levels (1.9 to 14.6 mg O2 l-1), and depths (1.8 to 29. but it was not present in trawls conducted during winter in. L. brevis, especially juveniles < 60 mm dorsal mantle length (DML), were abundant, frequently ranking in the upper 12% of overall annual nektonic trawl catches, and during the fall of some years, ranking second to anchovies. The probability of catching a squid increased in Chesapeake Bay at higher salinities and water temperatures, and was much greater in normoxic than in hypoxic waters; these variables had a profound influence on both annual and seasonal variability in distribution. Salinity had the largest influence on squid distribution, with squid being completely absent from the bay when salinity was <17.9” and most abundant in the fall when salinity was highest (despite declines in water temperature). Squid were most prevalent at depths between 10 and 15 m. The results of this study suggest that L. brevis is an important component of the Chesapeake Bay ecosystem when salinities and water temperatures are within tolerance limits and that unlike other squids, L. brevis may be well-equipped for an inshore, euryhaline existence.

KEY WORDS: Squid · Estuaries · Salinity · Water temperature · Dissolved oxygen · Lolliguncula brevis

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