The environmental problem focused here is the high death rate of immature trout in a specific fish hatchery. There were three causes identified to the problem – low levels of dissolved oxygen, high metal concentration and high degree of pesticides. Test hatchery has been developed to examine the mortality rates. The used samples are immature trout and do not fall under the same category.
To study the factor affecting mortality, two lake chemicals iron and lead have been regarded to identify the culprit between the two. Fish tank is used to study the fish behavior under controlled condition. The condition is entirely the same except that there is a variation in the lake chemical used. This type of controlled test can yield better and accurate results.
It has been cost 7 days to carry out the experiment. It can be known that one setup comprises of iron and the other contains lead. The concentration of the lake chemical is increased slowly based on the number of days. The mortality percentage is noted at the end of the day for 7 days. At the end of this experiment, the culprit is found out and the setup of lake is changed accordingly.
Two sets of experiments happened for iron and each lasted for 7 days. The first set comprised of 1.2ppm of iron and the mortality rate increased from 7.5% on first day to 12.5, 20.0, 25, 35, 50 and 60% on the last day. The other set comprised of 1.8ppm of iron and mortality rates were similar to previous batch, but on the final day, it stopped at 55% mortality rate.
In the case of lead, two sets happened when the first set comprised of 0.6ppm of lead and the projected mortality rate of was 0, 2.5, 5, 5, 5, 5 and ended at 7.5%. However, other set was exposed to 0.72ppm lead and showed consistent changes in mortality rate from 0, 2.5, 5, 5, 5, 7.5, 7.5 is the final result. The control mortality was nil throughout.
The acceptable level of dissolved oxygen in natural water is 8-11ppm. For trout, the acceptable nontoxic level of lead is 0.62 ppm. If the lead level is increased to 1.40ppm, it is regarded toxic. On the other hand, 1-2ppm iron is regarded as toxic to trout and 10ppm is also toxic. This implies that dissolved iron is less toxic and the natural water meant for the setting can have 0.1-0.7ppm iron on an average.
Based on the results, it is clear that iron is the culprit as it records 60% mortality rate. And when it is repeated with higher concentration, it records 55%, which is not a major difference. Iron is the toxic lake chemical that is responsible for the death of numerous trout exposed to testing. The lead levels are quite safe for the species, unlike the iron that can be toxic despite its concentration level.
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