Journal
MICROBIAL ECOLOGY
Volume 73, Issue 3, Pages 505-520Publisher
SPRINGER
DOI: 10.1007/s00248-016-0899-1
Keywords
Carbon stock; Structure equationmodels; Grazing; Degree of uncoupling
Categories
Funding
- Centrais Eletricas do Norte do Brasil S/A (ELETRONORTE)
- Brazilian National Council for Scientific and Technological Development (CNPq)
- CNPq
- Foundation for Research Support of the State of Sao Paulo (FAPESP) [2014/14139-3]
Ask authors/readers for more resources
Element cycling in aquatic systems is driven chiefly by planktonic processes, and the structure of the planktonic food web determines the efficiency of carbon transfer through trophic levels. However, few studies have comprehensively evaluated all planktonic food-web components in tropical regions. The aim of this study was to unravel the top-down controls (metazooplankton community structure), bottom-up controls (resource availability), and hydrologic (water residence time) and physical (temperature) variables that affect different components of the microbial food web (MFW) carbon stock in tropical reservoirs, through structural equation models (SEM). We conducted a field study in four deep Brazilian reservoirs (Balbina, Tucurui, Tres Marias, and Funil) with different trophic states (oligo-, meso-, and eutrophic). We found evidence of a high contribution of the MFW (up to 50% of total planktonic carbon), especially in the lesseutrophic reservoirs (Balbina and Tucurui). Bottom-up and top-down effects assessed through SEM indicated negative interactions between soluble reactive phosphorus and phototrophic picoplankton (PPP), dissolved inorganic nitrogen, and heterotrophic nanoflagellates (HNF). Copepods positively affected ciliates, and cladocerans positively affected heterotrophic bacteria (HB) and PPP. Higher copepod/cladoceran ratios and an indirect positive effect of copepods on HB might strengthen HB-HNF coupling. We also found low values for the degree of uncoupling (D) and a low HNF/HB ratio compared with literature data (mostly from temperate regions). This study demonstrates the importance of evaluating the whole size spectrum (including microbial compartments) of the different planktonic compartments, in order to capture the complex carbon dynamics of tropical aquatic ecosystems.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available