160
6. ApPLI CATIONS
The second application of simulation models of growth and form is in
the analysis of bioarchives. Separation of unnatural environmental change
from natural change and understanding the causes of natural change both
require records longer than those available from instruments, which cover
roughly the last 100 years (see Eddy and Oeschger 1993). Longer records
are recovered from substitute or proxy environmental records. For example,
certain documentary records - such as diaries, chronicles , and government
reports - provide information about the environment in the past . Biological
and geological processes also create proxy environmental records. Seasonal
growth of stalagmites and stalactites has provided information about variations in rainfall. Accumulation of seasonal snow in distinct layers over many
thousands of years in the Arctic, the Antarctic and at high elevations has
provided data for precipitation. Air bubbles trapped in the snow have provided information about atmospheric composition, and the oxygen isotopic
composition of the snow has provided information about temperature (e.g.
Delmas 1994, Thompson et al. 1995). Annual rings in trees are perhaps the
most familiar and certainly the most successful source of high-resolution
proxy environmental records. Annual rings form because, in sub-polar and
temperate regions, trees stop growing in winter. The distance between consecutive rings is then a measure of the excellence of the summer growing
season. Since many factors may affect tree growth , environmental information is usually recovered from trees at sites predominantly affected by one
environmental factor. Trees growing in semi-arid regions provide information about rainfall or soil moisture. Trees growing close to the upper tree
line record temperature over the short summer growing season (Fritts 1976,
Schweingruber 1988, Cook and Kairiukstis 1990). Bymatching rings in living
and dead trees, such records have been extended back for thousands of years.
There is a close relation between the growth process in marine sessile
organisms and the influence of the physical environment. There are many
examples of marine sessile organisms which are very suitable as proxy environmental recorders: stromatolites (Walter 1976), coralline algae (Bosence
1976), and coral skeletons. In Chap. 1 the example of the deep sea coral
Desmophyllum cristagalli was mentioned as an example of an environmental
recorder. In the second section of this chapter the analysis of the deposition
of growth layers in the stony coral Porites will be discussed in more detail.
In the first section sponges from the Antarctic will be given as another example of potential bioarchives. Although there are no clearly distinguishable
growth layers present in these organisms, because of their (estimated) enormous age and their location, these sponges might be a very important sour ce
of climatological information.
6.1 Antarctic Sponges
Antarctica has been called "the sponge kingdom" (Koltun 1968). More than
300 different species have been found in Antarctica and many benthic communities on the Antarctic shelf are clearly dominated by sponges (> 90 % of
biomass) (VoB 1988, Dayton 1974). Liketrees in a tropical rainforest, sponges
playa major role in structuring the habitat. Sponges provide living quarters "on the second floor" (Arntz et al. 1994) on the otherwise essentially flat
6. ApPLI CATIONS
The second application of simulation models of growth and form is in
the analysis of bioarchives. Separation of unnatural environmental change
from natural change and understanding the causes of natural change both
require records longer than those available from instruments, which cover
roughly the last 100 years (see Eddy and Oeschger 1993). Longer records
are recovered from substitute or proxy environmental records. For example,
certain documentary records - such as diaries, chronicles , and government
reports - provide information about the environment in the past . Biological
and geological processes also create proxy environmental records. Seasonal
growth of stalagmites and stalactites has provided information about variations in rainfall. Accumulation of seasonal snow in distinct layers over many
thousands of years in the Arctic, the Antarctic and at high elevations has
provided data for precipitation. Air bubbles trapped in the snow have provided information about atmospheric composition, and the oxygen isotopic
composition of the snow has provided information about temperature (e.g.
Delmas 1994, Thompson et al. 1995). Annual rings in trees are perhaps the
most familiar and certainly the most successful source of high-resolution
proxy environmental records. Annual rings form because, in sub-polar and
temperate regions, trees stop growing in winter. The distance between consecutive rings is then a measure of the excellence of the summer growing
season. Since many factors may affect tree growth , environmental information is usually recovered from trees at sites predominantly affected by one
environmental factor. Trees growing in semi-arid regions provide information about rainfall or soil moisture. Trees growing close to the upper tree
line record temperature over the short summer growing season (Fritts 1976,
Schweingruber 1988, Cook and Kairiukstis 1990). Bymatching rings in living
and dead trees, such records have been extended back for thousands of years.
There is a close relation between the growth process in marine sessile
organisms and the influence of the physical environment. There are many
examples of marine sessile organisms which are very suitable as proxy environmental recorders: stromatolites (Walter 1976), coralline algae (Bosence
1976), and coral skeletons. In Chap. 1 the example of the deep sea coral
Desmophyllum cristagalli was mentioned as an example of an environmental
recorder. In the second section of this chapter the analysis of the deposition
of growth layers in the stony coral Porites will be discussed in more detail.
In the first section sponges from the Antarctic will be given as another example of potential bioarchives. Although there are no clearly distinguishable
growth layers present in these organisms, because of their (estimated) enormous age and their location, these sponges might be a very important sour ce
of climatological information.
6.1 Antarctic Sponges
Antarctica has been called "the sponge kingdom" (Koltun 1968). More than
300 different species have been found in Antarctica and many benthic communities on the Antarctic shelf are clearly dominated by sponges (> 90 % of
biomass) (VoB 1988, Dayton 1974). Liketrees in a tropical rainforest, sponges
playa major role in structuring the habitat. Sponges provide living quarters "on the second floor" (Arntz et al. 1994) on the otherwise essentially flat