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Interactions between trophic levels in upwelling and non-upwelling regions during summer monsoon

DRS at CSIR-National Institute of Oceanography

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Title Interactions between trophic levels in upwelling and non-upwelling regions during summer monsoon
 
Creator Malik, A.
Fernandes, C.E.G.
Gonsalves, M.J.B.D.
Subina, N.S.
Mamatha, S.S.
Krishna, K.S.
Varik, S.
RituKumari
Gauns, M.
Cejoice, R.P.
Pandey, S.S.
Jineesh, V.K.
Kamaleson, A.S.
Vijayan, V.
Mukherjee, I.
Subramanyan, S.
Nair, S.
Ingole, B.S.
LokaBharathi, P.A.
 
Subject Coastal upwelling
Phytoplankton
Zooplankton
Parameters
Upwelling
Bacteria
Trophic levels
 
Description Coastal upwelling is a regular phenomenon occurring along the southwest coast of India during summer monsoon (May–September). We hypothesize that there could be a shift in environmental parameters along with changes in the network of interactions between bacteria, phytoplankton, and zooplankton in upwelling and non-upwelling regions. During cruise No 267 on FORV Sagar Sampada, water samples were analysed for environmental and biological parameters from two transects, one upwelling region off Trivandrum (TVM) (8°26`N, 76°20`E–8°30`N, 76°50`E), and the other non-upwelling region off Calicut (CLT) (11°11`N, 75°30`E–11°14`N,74°54`E), about 230 nmi to the north. Meteorological, hydrological, and nutrient profiles confirmed upwelling off TVM. Bacteria, phytoplankton and zooplankton significantly responded. Primary and bacterial productivity enhanced together with increase in the percentage of viable bacteria (TVC). Pearson's correlation analysis pointed out the differences in bacterial interactions with other trophic levels at both transects. TVC played a prominent role in trophic interactions off TVM by depending on phytoplankton for substrate (r = 0.754). This contrasted with CLT where total counts (TC) played an important role. However, most interrelationships were less pronounced. Principal component analysis (PCA) confirmed the correlation analysis and further showed that the factor loadings of the biotic and abiotic parameters differed in strength and direction in the two regions. More importantly, the processes of mineralization by bacteria and uptake by phytoplankton are obviously more coupled off TVM as evidenced by the clustering of the related parameters in the PCA biplot. Canonical correspondence analysis also complements these findings and demonstrated that the abiotic factors influenced phytoplankton and bacteria similarly at TVM but differently at CLT. The impact on the trophic interrelationships is evident by the close association between all the variables in upwelling waters. Besides, bacteria may represent a more stable element in the food web, TVC for upwelling region and TC for non-upwelling region
 
Date 2015-02-11T04:23:02Z
2015-02-11T04:23:02Z
2015
 
Type Journal Article
 
Identifier Journal of Sea Research, vol.95; 56-69
http://drs.nio.org/drs/handle/2264/4680
 
Language en
 
Rights An edited version of this paper was published by Elsevier. Copyright [2015] Elsevier
 
Publisher Elsevier