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Effect of Transient Acid Spikes on Developmental Stages of Lepomis Fishes

There is a developmental sensitivity to pH for most aquatic organisms. Ocean acidification due to increasing amounts of carbon dioxide is a current and future problem for organisms with the gradual lowering of the ocean pH. Carbon dioxide increases also can affect freshwater systems, but episodic acidity causes more problems with organisms in poorly buffered streams, ponds and lakes.

In this paper, the effects of transient acid spikes on development of Lepomis sunfish were studied by combining field work with laboratory studies. Lepomis sunfish eggs were collected from rocks on nests in two freshwater ponds and tested for their resistance to laboratory induced transient acid spikes. Fertilized eggs on rocks within the same nest were used for each pH transient experiment. Egg masses on one rock from the nest were used as a control while egg masses on another rock were exposed to transient acid spikes. Overall, 3163 early-life-stage Lepomis individuals (2459 eggs, 309 pre-swim-up larvae, and 395 Post-Swim-Up fry) taken from seven different nests were exposed to acid conditions in these experiments; another 1592 control individuals from the same nests were grown to the Post-Swim-Up stage in non-acid conditions.

The experiment findings indicated that various stages of development showed different responses to the acidic effects. The survival was high in the controls (94.0%); survival for groups exposed to acid water ranged from 85.5% to 0% (data pooled for groups with the same pH, duration of acid exposure, and life-stage). The major stages studied were fertilized egg, hatched with attached yolk sac, and free swimming with gills. The acid sensitivity followed development stages with the most acid sensitive stage being free swimming with gills.

In conclusion, this fieldwork-laboratory data chain supports earlier field studies, providing the final link in an evidentiary chain showing the effects of transient acid spikes on Lepomis hatching profiles in freshwater ponds.

Article by William G. Hagar, et al, from University of Massachusetts Boston, Boston, USA.

Full access: http://mrw.so/1aHM3G
Image by Matthieu Berroneau, from Flickr-cc.


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