Growth limitation in young Euphausia superba under field conditions. Limnol. Oceanogr

• Main Authors: Robin M. Ross, Langdon B. Quetin, Karen S. Baker, Maria Vernet, Raymond C. Smith
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2000
• Subjects: Antarctic; Antarc*; Antarctic Krill; Euphausia superba; Copepods
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.546.2793; http://www.aslo.org/lo/toc/vol_45/issue_1/0031.pdf

Growth rates of late furcilia and juvenile Antarctic krill (Euphausia superba Dana) in the spring and summer were related to food quantity and quality. The 4 yr covered by this study (1991–1992, 1993–1994, 1994–1995, and 1995–1996) were part of the seasonal time series of the Palmer Long-Term Ecological Research program. Chlo-rophyll a concentrations represented food quantity, and accessory photosynthetic pigments represented phytoplank-ton community composition or food quality. Instantaneous growth rates reflected the in situ nutritional history of the previous intermolt period. The response of krill to the food environment was seen on temporal scales of days to weeks. Percent growth per intermolt period (percentage growth IMP21) varied significantly both within and between years, ranging from;2 to 10 % IMP21. Percent growth IMP21 increased with increasing chlorophyll a (Chl a), reaching a maximum of 9.3 % IMP21 above a critical concentration of about 3.5 mg m23. Maximum growth was reached in only 2 yr, 1991–1992 and 1995–1996. In a multiple regression analysis, total Chl a and prymnesiophyte– Chl a explained over 71 % of the temporal variance in growth. In general, highest growth was found toward the end of diatom blooms and lowest during periods of low phytoplankton biomass or blooms dominated by crypto-phytes and prymnesiophytes. The results of this study support the hypothesis that maximum growth rates are only possible during diatom blooms and that production in Antarctic krill is limited by both food quantity and quality. The effects of food quantity and quality on production (growth and egg production) rates in marine and freshwater zooplankton has seldom been studied in situ. In a few pre-vious investigations, egg production in copepods (Checkley