کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4537418 | 1626473 | 2010 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Feeding impacts of ontogenetically migrating copepods on the spring phytoplankton bloom in the Oyashio region
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
زمین شناسی
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چکیده انگلیسی
We investigated the feeding habits and grazing rates of the ontogenetically migrating copepods in the Oyashio region to evaluate their grazing impacts on the food web during the spring phytoplankton bloom. The bloom was in progress from early to late April, although chlorophyll a concentrations fluctuated considerably with the frequent exchange of different water masses. Biomass of the copepod community reached a maximum in mid-April when late copepodites of Neocalanus cristatus, Neocalanus flemingeri and Eucalanus bungii contributed to the biomass increase. Gut pigment contents of the predominant copepods were much higher during the bloom compared with the levels in March (pre-bloom). The temporal fluctuations were not correlated with those of mean chlorophyll a concentrations in the 0-50Â m layer. Feeding experiments indicated that major food items for the copepods were centric diatoms and flagellates. During the period of lower ambient chlorophyll, the copepods changed their heterotrophic prey from naked ciliates to tintinnids. Apparent clearance rates were positive for naked ciliates and negative for heterotrophic nanoplankton, Cryptophyceae and bacteria when chlorophyll was high, suggesting trophic cascade effects from copepod feeding even during the phytoplankton bloom. The carbon demands of the copepod community were estimated to be 156 mgC mâ2 dayâ1 in early March to 797 mgC mâ2 dayâ1 in mid-April. The grazing rates on phytoplankton reached 480 mgC mâ2 dayâ1, equivalent to as much as 28% of primary production. Non-phytoplankton prey supported 40 to 71% of the copepod carbon requirement. These results suggest that the copepod community does not graze the phytoplankton bloom down, but it does have significant impacts on microbial food webs.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Deep Sea Research Part II: Topical Studies in Oceanography - Volume 57, Issues 17â18, September 2010, Pages 1703-1714
Journal: Deep Sea Research Part II: Topical Studies in Oceanography - Volume 57, Issues 17â18, September 2010, Pages 1703-1714
نویسندگان
T. Kobari, Y. Inoue, Y. Nakamura, H. Okamura, T. Ota, Y. Nishibe, M. Ichinomiya,