<P> A large increase in temperature can lead to the denaturing of life - supporting enzymes by breaking down hydrogen - and disulphide bonds within the quaternary structure of the enzymes . Decreased enzyme activity in aquatic organisms can cause problems such as the inability to break down lipids, which leads to malnutrition . </P> <P> In limited cases, warm water has little deleterious effect and may even lead to improved function of the receiving aquatic ecosystem . This phenomenon is seen especially in seasonal waters and is known as thermal enrichment . An extreme case is derived from the aggregational habits of the manatee, which often uses power plant discharge sites during winter . Projections suggest that manatee populations would decline upon the removal of these discharges . </P> <P> Releases of unnaturally cold water from reservoirs can dramatically change the fish and macroinvertebrate fauna of rivers, and reduce river productivity . In Australia, where many rivers have warmer temperature regimes, native fish species have been eliminated, and macroinvertebrate fauna have been drastically altered . This may be mitigated by designing the dam to release warmer surface waters instead of the colder water at the bottom of the reservoir . </P> <P> When a power plant first opens or shuts down for repair or other causes, fish and other organisms adapted to particular temperature range can be killed by the abrupt change in water temperature, either an increase or decrease, known as "thermal shock". </P>

How could heat be a pollutant what damage could it cause