Appraisal of Warm-Temperate South African Mangrove Estuaries as Habitats to Enhance Larval Nutritional Condition and Growth of Gilchristella aestuaria (Family Clupeidae) Using RNA:DNA Ratios

Appraisal of Warm-Temperate South African Mangrove Estuaries as Habitats to Enhance Larval... Estuaries are highly dynamic systems that serve as nursery areas to fishes and are likely to vary in nursery function, mostly due to habitat quality and food availability. Mangroves are thought to be good nurseries as they enhance food availability and protection, improving growth and survival of juvenile fishes. Food quantity and quality may be reflected in nutritional condition, which may in turn be a useful proxy for growth and survival of larval fishes. This study compared the nutritional condition and growth rate of 793 late stage larvae of estuarine roundherring, Gilchristella aestuaria, by using RNA:DNA indices to indirectly compare the feeding environment among similar warm-temperate mangrove and non-mangrove estuaries in South Africa during January 2015 and 2016. Results indicated that G. aestuaria larvae had differing nutritional conditions within the sampling years and within the estuaries. The standardised RNA:DNA (sRD) as well as the RNA residual index values were higher within mangrove estuaries only in 2016. The instantaneous growth rates (Gi) of larvae in mangrove and non-mangrove estuaries were similar; however, post-flexion larvae were found to have a higher Gi and sRD in mangrove estuaries. Turbidity was the major factor influencing the nutritional condition of G. aestuaria larvae. Mangroves have been found to act as sediment sinks and thus may provide advantages that increase feeding success for post-flexion larvae; however, more is yet to be understood in terms of feeding environment dynamics and how habitat quality influences the survival of larval fishes. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Estuaries and Coasts Springer Journals

Appraisal of Warm-Temperate South African Mangrove Estuaries as Habitats to Enhance Larval Nutritional Condition and Growth of Gilchristella aestuaria (Family Clupeidae) Using RNA:DNA Ratios

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Publisher
Springer Journals
Copyright
Copyright © 2018 by Coastal and Estuarine Research Federation
Subject
Environment; Environment, general; Ecology; Freshwater & Marine Ecology; Environmental Management; Coastal Sciences; Water and Health
ISSN
1559-2723
eISSN
1559-2731
D.O.I.
10.1007/s12237-018-0375-x
Publisher site
See Article on Publisher Site

Abstract

Estuaries are highly dynamic systems that serve as nursery areas to fishes and are likely to vary in nursery function, mostly due to habitat quality and food availability. Mangroves are thought to be good nurseries as they enhance food availability and protection, improving growth and survival of juvenile fishes. Food quantity and quality may be reflected in nutritional condition, which may in turn be a useful proxy for growth and survival of larval fishes. This study compared the nutritional condition and growth rate of 793 late stage larvae of estuarine roundherring, Gilchristella aestuaria, by using RNA:DNA indices to indirectly compare the feeding environment among similar warm-temperate mangrove and non-mangrove estuaries in South Africa during January 2015 and 2016. Results indicated that G. aestuaria larvae had differing nutritional conditions within the sampling years and within the estuaries. The standardised RNA:DNA (sRD) as well as the RNA residual index values were higher within mangrove estuaries only in 2016. The instantaneous growth rates (Gi) of larvae in mangrove and non-mangrove estuaries were similar; however, post-flexion larvae were found to have a higher Gi and sRD in mangrove estuaries. Turbidity was the major factor influencing the nutritional condition of G. aestuaria larvae. Mangroves have been found to act as sediment sinks and thus may provide advantages that increase feeding success for post-flexion larvae; however, more is yet to be understood in terms of feeding environment dynamics and how habitat quality influences the survival of larval fishes.

Journal

Estuaries and CoastsSpringer Journals

Published: Feb 13, 2018

References

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