Intra-lake stable isotope ratio variation in selected fish species and their possible carbon sources in Lake Kyoga (Uganda): implications for aquatic food web studies

2009 ◽  
Author(s):  
Dismas Mbabazi ◽  
B. Makanga ◽  
F. Orach-Meza ◽  
R. E. Hecky ◽  
J.S. Balirwa ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Fish Species ◽  
Isotope Ratio ◽  
Carbon Sources ◽  
Stable Isotope Ratio ◽  
Aquatic Food Web ◽  
Web Studies ◽  
Ratio Variation ◽  
Aquatic Food

scholarly journals Preliminary examination of food web structure of Nicola Lake (Taim Hydrological System, south Brazil) using dual C and N stable isotope analyses

2006 ◽  
Vol 4 (2) ◽  
pp. 279-284 ◽  
Author(s):  
Alexandre M. Garcia ◽  
David J. Hoeinghaus ◽  
João P. Vieira ◽  
Kirk O. Winemiller ◽  
David M. L. Motta Marques ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Biological Diversity ◽  
Isotope Analysis ◽  
Carbon Sources ◽  
Stable Isotope Ratio ◽  
Trophic Levels ◽  
Food Web Structure ◽  
Web Structure ◽  
Hydrological System

Taim Ecological Reserve is located within the Taim Hydrological System and was created to protect a heterogeneous and productive landscape harboring exceptional biological diversity in southern Brazil. Using stable isotope ratio analyses of carbon (delta13C) and nitrogen (delta15N), we provide a preliminary description of the food web structure, including estimates of production sources supporting fish populations and vertical trophic structure, within a representative lake of this system. A total of 21 organisms (5 macrophytes, 3 mollusks and 13 adult fishes) representing 16 species were collected for isotope analysis. Fishes had delta13C values ranging from -24.30º/oo to -28.31º/oo , showing concordance with the range of values observed for macrophytes (-25.49 to -27.10º/oo), and suggesting that these plants could be a major carbon source supporting these fishes. delta13C signatures of Corbicula (-30.81º/oo) and Pomacea (-24.26º/oo) indirectly suggest that phytoplankton and benthic algae could be alternative carbon sources for some consumers. Nitrogen isotope ratios indicated approximately three consumer trophic levels. The pearl cichlid Geophagus brasiliensis was a primary consumer. Two catfishes (Trachelyopterus lucenai and Loricariichthys anus) were secondary consumers. Two congeneric pike cichclids (Crenicichla lepidota and C. punctata), a catfish (Pimelodus maculatus) and the characids Astyanax fasciatus and Oligosarcus robustus were tertiary consumers. Further studies including additional primary producers and consumers and greater sample numbers should be conducted to provide a more complete and detailed description of food web structure and dynamics within the reserve.

Dynamics of bacteria–substrate stable isotope separation: dependence on substrate availability and implications for aquatic food web studies

2008 ◽  
Vol 65 (9) ◽  
pp. 1983-1990 ◽  
Author(s):  
Daryl J. McGoldrick ◽  
David R. Barton ◽  
Michael Power ◽  
Ryan W. Scott ◽  
Barbara J. Butler
Keyword(s):  
Food Web ◽  
Exponential Growth Phase ◽  
Substrate Availability ◽  
Aquatic Food Web ◽  
Fish Food ◽  
Web Studies ◽  
Isotopic Signatures ◽  
C And N ◽  
Isotopic Separation ◽  
Aquatic Food

Heterotrophic bacteria growing without substrate limitation discriminate against the heavier stable isotopes of C and N, which is reflected in the isotopic signatures of consumers of bacteria. We measured bacteria and substrate isotopic separation (C and N) during glucose and ammonium uptake by three strains of bacteria ( Pseudomonas putida , Bacillus megaterium , and Enterobacter aerogenes ) grown in batch culture at 4 and 30 °C. Isotopic separation between bacteria and substrate was dependent on substrate availability. Higher discrimination against the heavier isotopes, and therefore more depleted δ13C and δ15N values of bacterial biomass, were observed during the exponential growth phase when the nutrient supply was in excess of the demand. We also compared the isotopic ratios of Chironomus tentans grown on aged macrophyte detritus and commercial fish food. Isotopic signatures of Chironomus larvae grown on fish food were within the ranges typical of one trophic step, whereas larvae grown on detritus were strongly depleted in13C, suggesting assimilation of bacteria that had grown on the C-rich detritus. Our results are consistent with the very few other studies of bacterial fractionation of nonlimiting nutrients and may also explain the frequent observation of unexpectedly depleted isotopic signatures in aquatic food web studies.

Assigning hydrogen, carbon, and nitrogen isotope values for phytoplankton and terrestrial detritus in aquatic food web studies

Inland Waters ◽  
2014 ◽  
Vol 4 (2) ◽  
pp. 233-242 ◽  
Author(s):  
Carol Yang ◽  
Grace Wilkinson ◽  
Jonathan Cole ◽  
Stephen Macko ◽  
Michael Pace
Keyword(s):  
Food Web ◽  
Nitrogen Isotope ◽  
Aquatic Food Web ◽  
Web Studies ◽  
Carbon And Nitrogen ◽  
Aquatic Food

Carbon sources for aquatic food webs of riverine and lacustrine tropical waterholes with variable groundwater influence

2017 ◽  
Vol 68 (3) ◽  
pp. 442 ◽  
Author(s):  
N. E. Pettit ◽  
D. M. Warfe ◽  
P. G. Close ◽  
B. J. Pusey ◽  
R. Dobbs ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Isotope Analysis ◽  
Carbon Sources ◽  
Freshwater Wetlands ◽  
Food Sources ◽  
Web Studies ◽  
Aquatic Food Webs ◽  
Aquatic Food ◽  
Groundwater Reserves

Food web studies integrate ecological information and provide understanding of ecosystem function. Aquatic ecosystems of the Kimberley region (north-western Australia) have high conservation significance as hotspots for maintaining local and regional biodiversity. This study investigated the influence of waterhole type and persistence on the strength of consumer reliance on local energy resources for aquatic food webs. Changes in water isotopic composition indicated groundwater inputs were enough to overcome evaporative losses in some waterholes. Other waterholes had varying levels of isotope enrichment suggesting insufficient groundwater input to ‘compensate’ for evaporative loss. C and N isotope analysis indicated considerable overlap among energy sources in waterholes between macrophytes and periphyton but gradient analysis indicated that periphyton is a major carbon source for aquatic consumers. Groundwater-fed waterholes appeared to have higher quality food sources (indicated by lower C:N ratios), but there was minimal evidence that direct groundwater contributions were related to food web processes. Nonetheless, in a region where groundwater is influential in maintaining aquatic habitats, future development of groundwater reserves will likely affect the ecological and cultural value of freshwater wetlands by either reducing their permanence or size or indirectly through possible alteration to the role of periphyton in supporting the food web.

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