B 20NJ Kiuwer Acoderr~tc Pnb l~her s. Printed in!he Nerherlantl<. The effect of water depth on bacterial numbers, thymidine incorporation rates and C:N ratios in northeast Atlantic surficial sediments

• Main Authors: J. L. Djxon, C. M. Turley
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Key words; bacteria numhers; 3~]-thyrnidinc incorpuratic~n; deep sea; surficial sediment; phytodetritus; northeast Atlantic; Northeast Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.602.1882; http://www.db.uac.pt/pdf/island/28_water.pdf

The effect of water depth on bacterial biomass and their ability to sy nthesisc DNA. by measuring their rate of ["I-thymidine incorporation, was investigated in the northeast Atlantic at three sites of varying waLer depth (1 100-3580 m) and sediment characteristics. Thymidine incorporation rates Cy) in surficial sediments varied between 0.028 and 1.44 pmol h- ' g- ' and showed an exponential relationship with depth ( x) according to the equation y = 2,05e-0.~0 ~ x (r=0.9830 for n=7, PcO.OU 1). However, this relationship failed when a layer of phy todetritus was found overlying the sucfacc scdirnent and [3 HI-thymidine incorporation rates increased by 8s339'90. In contrast, baclerial numhers varied between 1.09 and 1 1.96 x 10%lls llsg ' (dry weight) and showed no significant re-lationships with water depth or scdiment P O m N content. Significant exponential rcla~ionships werc also found between walcr depth (x) and the POT: Cy 1) and totsll nitrogen (TN, y z) content of suficial sediments according to the following equations: where yl = 7 19c-.0,0DO'X ( rd.8700 for n=9, f ~0.01) and yz = 76eL0.0002"(r=0.7582 for n=9 Pt0.02). These relationships were irrespective of the presence or absence of an overlying layer of phytodetritus. This suggests that the POC and TN cantent of these surficial deep sea sediments i s dircctly rclaied to the flux of malerial though the water column, which significantly impacts bacterial produc~ian.