However, every increase in temperature causes an increase of the flow of energy in
the ecosystem similar to the increases that occur in chemical processes at elevated
temperatures. Primary production - that is, photosynthesis - is increased modestly.
But the consumption of plant food by animals and the rate of the degradation of
dead organic matter by bacteria is increased even more. The result of this activity is
increased respiration, in other words, increased consumption of oxygen. But even at
higher temperatures, the ecologically harmonious relationship in balanced communities can remain balanced (Fig. 1).
In principle, one could estimate how an increase in temperature affects the various
components of an ecosystem, because one can apply the reaction rate rule (reaction
time, approximately doubled at a 10°C increase in temperature) to life-activity-temperature correlations as one does in chemical processes. They do not need to be
applicable in each and every case, because it has become increasingly clear in recent
years through physiological experiments that many organisms have plateaus in which
the activity does not change beyond a certain temperature range. Knowledge about
this is not yet detailed enough; and information about the interrelationships in the
ecosystem is also as yet insufficient, so that accurate simulations of even simple ecosystems are still in the infant stage. Nevertheless, available knowledge is ample enough
to model, for example, the effect of an increase in temperature of 3°C, and compare
with measurements (McKellar 1977):
The Crystal River power plant with a capacity of 900 MW, has been in operation on
the Gulf of Mexico since 1966. It heats cooling water at 40 m 3 /s by 5
0
-6°C and
releases it into the lagoon system off the coast. The natural range of the water temperature in the lagoons during the year is between 14° and 30°C. The winter temperature of the special lagoon into which the cooling water is released is 15°C; in the
summer it is 33°C. The phytoplankton biomass was somewhat less here than in the
control area but the turnover rate was 5 days, 24 h faster than it was in the unwarmed
area. The zooplankton was somewhat more numerous in the heated lagoon, the
benthos somewhat less than in the comparison area.
The computer simulation for the summer gave a primary production that was 10%
higher and a zooplankton biomass that was 10% less than observed; the computer
simulation therefore does not agree completely with the data gathered by observation. Thus, the computer simulation for an additional 4°C increase in temperature
(winter 19°C, summer 37°C) might also be speculative: an unaltered phytoplankton
biomass with a distinctly higher respiration results, in the spring, in a higher primary
production. The zooplankton should diminish by 40% in the summer; in the winter
it should be similar in number to that of the unheated lagoons. In the summer, there
should be 40% fewer fish in the heated water; in the winter, however, there should
be 60% to 70% more than in the control areas because fish migrate and always seek
optimal water temperatures.
Basic marine biologiy certainly has a long way to go before such simulations achieve
sufficient reliability that they can be used as a predictive instrument. This is because
the adaptation relationships of the organisms are reciprocally complex. Under the
restricted conditions in estuaries, the oxygen level assumes a key position. Increased
temperatures work in the same direction as an increased organic stress. At higher
temperatures, the metabolism of bacteria accelerates and their oxygen consumption
32
the ecosystem similar to the increases that occur in chemical processes at elevated
temperatures. Primary production - that is, photosynthesis - is increased modestly.
But the consumption of plant food by animals and the rate of the degradation of
dead organic matter by bacteria is increased even more. The result of this activity is
increased respiration, in other words, increased consumption of oxygen. But even at
higher temperatures, the ecologically harmonious relationship in balanced communities can remain balanced (Fig. 1).
In principle, one could estimate how an increase in temperature affects the various
components of an ecosystem, because one can apply the reaction rate rule (reaction
time, approximately doubled at a 10°C increase in temperature) to life-activity-temperature correlations as one does in chemical processes. They do not need to be
applicable in each and every case, because it has become increasingly clear in recent
years through physiological experiments that many organisms have plateaus in which
the activity does not change beyond a certain temperature range. Knowledge about
this is not yet detailed enough; and information about the interrelationships in the
ecosystem is also as yet insufficient, so that accurate simulations of even simple ecosystems are still in the infant stage. Nevertheless, available knowledge is ample enough
to model, for example, the effect of an increase in temperature of 3°C, and compare
with measurements (McKellar 1977):
The Crystal River power plant with a capacity of 900 MW, has been in operation on
the Gulf of Mexico since 1966. It heats cooling water at 40 m 3 /s by 5
0
-6°C and
releases it into the lagoon system off the coast. The natural range of the water temperature in the lagoons during the year is between 14° and 30°C. The winter temperature of the special lagoon into which the cooling water is released is 15°C; in the
summer it is 33°C. The phytoplankton biomass was somewhat less here than in the
control area but the turnover rate was 5 days, 24 h faster than it was in the unwarmed
area. The zooplankton was somewhat more numerous in the heated lagoon, the
benthos somewhat less than in the comparison area.
The computer simulation for the summer gave a primary production that was 10%
higher and a zooplankton biomass that was 10% less than observed; the computer
simulation therefore does not agree completely with the data gathered by observation. Thus, the computer simulation for an additional 4°C increase in temperature
(winter 19°C, summer 37°C) might also be speculative: an unaltered phytoplankton
biomass with a distinctly higher respiration results, in the spring, in a higher primary
production. The zooplankton should diminish by 40% in the summer; in the winter
it should be similar in number to that of the unheated lagoons. In the summer, there
should be 40% fewer fish in the heated water; in the winter, however, there should
be 60% to 70% more than in the control areas because fish migrate and always seek
optimal water temperatures.
Basic marine biologiy certainly has a long way to go before such simulations achieve
sufficient reliability that they can be used as a predictive instrument. This is because
the adaptation relationships of the organisms are reciprocally complex. Under the
restricted conditions in estuaries, the oxygen level assumes a key position. Increased
temperatures work in the same direction as an increased organic stress. At higher
temperatures, the metabolism of bacteria accelerates and their oxygen consumption
32