9.5 The Biotic Ingredients of the Wadden Sea
243
9.5
The Biotic Ingredients of the Wadden Sea
9.5.1 Bacteria
Variables of interest
Species diversity among the bacteria is presumably higher than that of all other
species in the Wadden Sea taken together. With respect to the whole Wadden Sea,
however, it is not the individual bacteria species which matter, but rather their
overall performance, i.e. the remineralization of dead organic matter. The main
variable of interest characterizing the activity of heterotrophic bacteria is thus the
rate of remineralization. Another variable of interest is the overall biomass of
bacteria, because they represent an important food resource for higher organisms.
This variable has, however, not yet been sufficiently studied in quantitative terms.
Significance of the ingredient for the Wadden Sea
The high rate of primary production in the Wadden Sea (see 9.5.2) leads to high
consumption rates of nutrients. Thus the high rate of primary production depends
on a sufficient supply of nutrients. This supply does not only occur via exchange
with water from the North Sea or input from rivers, but mainly via the remineralization of dead organic matter in the sediment by bacteria. The activity of the bacteria is thus crucial for the high primary production in the Wadden Sea.
Stability properties: persistence and resilience
The performance of bacteria is extremely persistent with respect to nutrient cycling
in the Wadden Sea, and extremely resilient as far as local disturbances of higher
inputs of organic matter are concerned (Chap. 5.2). This high persistence and resilience are very likely to apply as well to their role as food supply for the meioand macrofauna (Reise 1985).
Stability mechanisms
The decisive mechanism responsible for these stability properties is the extremely
high functional diversity of bacteria, which is a consequence not only of the high
species diversity but also of the high metabolic flexibility. For any type of resources (e.g., fresh or refractory organic matter) and for almost any type of local
environment (e.g., oxic, anoxic, different concentrations of sulphate, nitrate, etc.;
Chap. 5.2) different species or different metabolic pathways exist which can very
quickly start remineralization at the highest rate possible in that particular environment. This high adaptability of bacteria to even sudden and extreme changes of
their environment was demonstrated by ELA W AT in laboratory experiments in
which organic matter was added to sandy sediment (Chap. 5.2). Twelve hours after
incubation with the organic substrate, only 5 % of the substrate had decomposed,
this figure rising to 90 % after just 36 hours. Thus, the bacteria are able to produce
243
9.5
The Biotic Ingredients of the Wadden Sea
9.5.1 Bacteria
Variables of interest
Species diversity among the bacteria is presumably higher than that of all other
species in the Wadden Sea taken together. With respect to the whole Wadden Sea,
however, it is not the individual bacteria species which matter, but rather their
overall performance, i.e. the remineralization of dead organic matter. The main
variable of interest characterizing the activity of heterotrophic bacteria is thus the
rate of remineralization. Another variable of interest is the overall biomass of
bacteria, because they represent an important food resource for higher organisms.
This variable has, however, not yet been sufficiently studied in quantitative terms.
Significance of the ingredient for the Wadden Sea
The high rate of primary production in the Wadden Sea (see 9.5.2) leads to high
consumption rates of nutrients. Thus the high rate of primary production depends
on a sufficient supply of nutrients. This supply does not only occur via exchange
with water from the North Sea or input from rivers, but mainly via the remineralization of dead organic matter in the sediment by bacteria. The activity of the bacteria is thus crucial for the high primary production in the Wadden Sea.
Stability properties: persistence and resilience
The performance of bacteria is extremely persistent with respect to nutrient cycling
in the Wadden Sea, and extremely resilient as far as local disturbances of higher
inputs of organic matter are concerned (Chap. 5.2). This high persistence and resilience are very likely to apply as well to their role as food supply for the meioand macrofauna (Reise 1985).
Stability mechanisms
The decisive mechanism responsible for these stability properties is the extremely
high functional diversity of bacteria, which is a consequence not only of the high
species diversity but also of the high metabolic flexibility. For any type of resources (e.g., fresh or refractory organic matter) and for almost any type of local
environment (e.g., oxic, anoxic, different concentrations of sulphate, nitrate, etc.;
Chap. 5.2) different species or different metabolic pathways exist which can very
quickly start remineralization at the highest rate possible in that particular environment. This high adaptability of bacteria to even sudden and extreme changes of
their environment was demonstrated by ELA W AT in laboratory experiments in
which organic matter was added to sandy sediment (Chap. 5.2). Twelve hours after
incubation with the organic substrate, only 5 % of the substrate had decomposed,
this figure rising to 90 % after just 36 hours. Thus, the bacteria are able to produce