The top of the 60-foot waterfall.
Electrocardiograms recorded during the toxic syndrome indicated that the animals died from ventricular fibrillation due to a direct effect of ammonia on the heart.
This blog post is also worth a read, by the way:
(2011): Preliminary study on the unusual properties in the habitat of Ranunculetum baudotii in Central Europe.
Central European Journal of Biology 6 (4): 632-638
Inhalation exposure (a) Ruminants Marschang & Crainiceanu (1971) measured the ammonia concentrations in air (sampled at nose level of animals) in calf stables at 4 dairy farms in Romania.
Scenario for the origin of photoreceptor cells
For fresh-water organisms, the families most sensitive in terms of chronic toxicity are Salmonidae and Catostomidae, pink salmon and white sucker being the most sensitive species within these families.
3 Ciliary photoreceptors in the eyes of extant chordates
The ‘improved’ C-opsin that had emerged during chordate evolution, with a high efficacy of G-protein activation and with rapid release of all- retinal, became the ancestral cone opsin. Furthermore, there is strong evidence that, prior to the ‘2R’ whole genome duplications at the base of the vertebrate lineage, this ancestral cone opsin had already duplicated into the ancestral pair of SWS and LWS cone opsins. However, it is more convenient to consider that evidence later, in Section 6 on vertebrate visual opsins.
Evaluation of the health risks for man and effects on the environment
Limited chronic toxicity data for invertebrates, mostly cladocerans and one insect species, indicate that they are generally more tolerant than fish, although the fingernail clam appears to be as sensitive as salmonids.
Sources releasing ammonia into the air
The prawn, Macrobrachium rosenbergii, appears to be the most sensitive invertebrate species tested, and the red drum, the most sensitive fish species.
Transport to the earth's surface
Single exposures There have been many estimates of inhalational toxicity in which the theoretical relationship between concentration, duration of exposure, and lethality has been observed.
EFFECTS ON ORGANISMS IN THE ENVIRONMENT
Data on temperature effects on acute NH3 toxicity are limited and variable, but there are indications that NH3 toxicity is greater at low (< 10 °C) temperatures.