The effects of supersaturated nitrogen on the endangered fountain darter and the San Marcos salamander
Schaefer, Peter E.
A chronic and an acute toxicity test were conducted to determine the effects of dissolved nitrogen gas (DN) supersaturation on the fountain darter Etheostoma fonticola and the San Marcos salamander Eurycea nana. In the chronic toxicity test, fountain darter fry, juvenile and adults were exposed to DN saturation levels of 90, 104, 118 and 136% for 28 d. Adult fountain darters died from gas bubble trauma (GBT) only at 136% in the chronic toxicity test. Fry and juveniles showed no external signs of GBT at any of these levels. Adults produced eggs at all treatment levels in both tests with no significant difference in the number of eggs produced between treatments. In the acute toxicity test, fountain darter fry, fountain darter adults and adult San Marcos salamanders were exposed to DN saturation levels of 106, 124, 130 and 143% for 96 Ii. Only adult fountain darters died from GBT and only at 130 and 143% DN saturation during the acute toxicity test. Three out of36 San Marcos salamanders and three fountain darter fry exhibited signs of GBT at 143% DN saturation but did not die. The 96-h LC50 for adult fountain darters was 138% DN saturation. The LTS0's for adult fountain darters were 12 din 136% DN saturation and 48 h in 143% DN saturation.
Etheostoma, Brook salamanders, Nitrogen supersaturation, Endangered fountain darter
Schaefer, P. E. (2000). <i>The effects of supersaturated nitrogen on the endangered fountain darter and the San Marcos salamander</i> (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.