Contrasting environmental drivers of fish growth
Joyce Ong, Jessica Meeuwig | Jun 08, 2015
Mangrove jack (Lutjanus argentimaculatus) approaching an underwater baited camera station (BRUVS).
Photo: Centre for Marine Futures.
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Ong JJ, Rountrey AN, Meeuwig JJ, Newman SJ, Zinke J, Meekan MG. 2015. Contrasting environmental drivers of adult and juvenile growth in a marine fish: Implications for the effects of climate change. Scientific Reports, 5: art10859.
- Our climate is rapidly changing and water temperatures in the ocean have been on the rise for several years.
- Being able to predict how climate shifts will affect the growth of marine species is crucial, but has not been fully explored due to the lack of appropriate long term data sets.
- We examined how historical climate fluctuations have affected the growth of a commercially important tropical snapper species (the mangrove jack, Lutjanus argentimaculatus) in north-western Australia.
- We used light microscopy to image the otoliths and analysed the snappers’ growth patterns based on ring counts.
- Fish grew faster under warm and hyposaline conditions, conditions typical of La Niña years.
- Such events are predicted to be less frequent but more extreme in the future, indicating potentially tough times ahead for snappers.
Many marine fishes have life history strategies that involve ontogenetic changes in the use of coastal habitats. Such ontogenetic shifts may place these species at particular risk from climate change, because the successive environments they inhabit can differ in the type, frequency and severity of changes related to global warming. We used a dendrochronology approach to examine the physical and biological drivers of growth of adult and juvenile mangrove jack (Lutjanus argentimaculatus) from tropical north-western Australia.
Juveniles of this species inhabit estuarine environments and adults reside on coastal reefs. The Niño-4 index, a measure of the status of the El Niño-Southern Oscillation (ENSO) had the highest correlation with adult growth chronologies, with La Niña years (characterised by warmer temperatures and lower salinities) having positive impacts on growth. Atmospheric and oceanographic phenomena operating at ocean-basin scales seem to be important correlates of the processes driving growth in local coastal habitats. Conversely, terrestrial factors influencing precipitation and river runoff were positively correlated with the growth of juveniles in estuaries. Our results show that the impacts of climate change on these two life history stages are likely to be different, with implications for resilience and management of populations.
FUNDING & ACKNOWLEDGEMENTS
The authors acknowledge the facilities, and the scientific and technical assistance of the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy, Characterisation & Analysis, the University of Western Australia, a facility funded by the University, State and Commonwealth Governments. In particular, we would like to thank Professor Paul Rigby and Miss Alysia Buckley for the help and advice they have provided. This work was funded by the Australian National Network in Marine Science, the Australian Institute of Marine Science and conducted as part of a PhD thesis funded by a scholarship from the Australian Postgraduate Awards. J.Z. was supported by a UWA/AIMS/CSIRO fellowship and an Honorary Research Fellowship with the University of the Witwatersrand.
FISH EAR STONES
Light micrograph of the dorsal side of a Lutjanus argentimaculatus (mangrove jack) otolith section, showing successive growth rings (Photograph: Joyce Ong).
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