Trophic Cascading of Medusae on the Relationships between Copepods and Diatoms in a Subtropical Coastal Ecosystem
Resource
TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES,20(3),547-556.
Journal
Terrestrial Atmospheric and Oceanic Sciences
Pages
547
Date Issued
2009-06
Date
2009-06
Author(s)
Chung, J. L.
Shiah, F. K.
Gong, G. C.
Chiang, K. Ping
Abstract
To in ves ti gate the spa tial and tem po ral vari a tion of phytoplankton and copepods, eight sea sonal cruises (Jan u ary 2005 c to ber 2006) were con ducted in a sub trop i cal coast site that en com passed 19 sam pling sta tions. The re sults in di cated that the tem per a ture (18.4 -29.7C) var ied more than 10C sea son ally, while nu tri ent con cen tra tions (ni trate: 0.4 -6.3 mM, phos phate: 0.1 -0.8 mM, and sil i cate 2.1 -12.1 mM) were in versely cor re lated with tem per a ture. Di a toms (2792 -1602437 cells m -3 ) con sti tuted > 90% of the phytoplankton as sem blages and dinoflagellates (226 -10029 cells m -3 ) rep re sented only ~10% of the al gae bio mass. Copepod abun dance (8 -1031 ind. m -3 ) var ied pos i tively with that of di a tom and tem per a ture. The rel a tive abun dance of Temora spp. (1 -712 ind. m -3 ) var ied from 69% in sum mer; that of Paracalanus spp. (0.1 -176 ind. m -3 ) were > 25% in spring and au tumn and Calanus spp. (0.5 -24 ind. m -3 ) dom i nated in win ter and spring, but ac counted for only ~10% of the to tal copepods. Both di a tom den sity and copepod abun dance were pos i tively cor re lated with tem per a ture, in di cat ing these two plank ton groups were left bot tom-up con trol. The copepod abun dance pos i tively co-var ied with di a toms in 2005, but not in 2006. Fur ther sea son-to-sea son anal y sis showed that the di a tom vs. copepod ra tios changed pos i tively only when the medusa abun dance changed greatly (> 40-fold) be tween con sec u tive sea sons. Dur ing pe ri ods when the medusa abun dance var ied less than 10-fold be tween sea sons, there is no re la tion ship be tween the ra tios and the medusa abun dance. This study sug gests that the sta bil ity of the medusa abun dance from season to season could be important in regulating the ecological linkage between diatoms and their predators -copepods.
SDGs
Type
journal article