Winter input
Resuspended sediment, terrestrial material and eroded macrophytes represent an additional food supply for the benthic community during winter (Fig. 1). Although heat
production continuously decreased, a high level of benthic biomass accumulated. This
applies for bacterial biomass as well (Fig. 2). The high bacterial biomass sustained during
winter is surprising taking into account the low temperature and the reduced metabolic
activity rates. However, limited number of grazers and the relatively long time the
bacteria had available for their “undisturbed” development may explain the biomass
accumulation. Additionally, the more refractory kind of food source could have been
responsible for the slow, continuous increase in bacterial biomass in winter. In this
respect, the development of the bacterial population in winter differed basically from its
spontaneous development in autumn and spring, respectively.
Fauna development
Additional samples taken in late spring revealed that the further fate of the bacterial
community was greatly influenced by the development of the benthic fauna (data not
shown ; Meyer-Reil 1983). A mass occurrence of polychaetes in the sediment was accompanied by a high number of almost exclusively small-size bacteria (volume <0,3µm3)
which actively grew (high number of dividing cells). Most likely preferentially grazing of
medium and large-size cells by the polychaetes was the reason for the impoverishment of
the bacterial population.There is indeed evidence from the literature that grazing stimulates bacterial activity (Morrison and White, 1980).
CONCLUSION
From the foregoing discussion it becomes obvious that processes like sedimentation and
input of organic material into the sediment may occur in very short time scales (within
days), causing an immediate response of benthic activities. Whereas the succession of
certain processes in the benthic community could be explained by the interactions
between individual parameters, other processes still need explanation. This applies
especially to the decline of benthic activities and biomass after certain levels were reached.
Control mechanisms, such as the growth limiting effect of certain population densities
and interactions between the individual components of the benthic communities, have to
be considered.
GRAF G., R. SCHULZ, R. PEINERT and L.-A. MEYER-REIL., 1983. Benthic response to sedimentation events
during autumn to spring at a shallow water station in the Western Kiel Bight I. Analysis of processes on a
community level. Mar. Biol. 77 : 235 - 246.
HARGRAVE B.T., 1980. Factors affecting the flux of organic matter to sediments in a marine bay. In : K.R.
Tenore and B.C. Coull (Eds.) Marine benthic dynamics. Columbia : Univ. South Carolina Press : 243-263.
MEYER-REIL L.-A., 1983. Benthic response to sedimentation events during autumn to spring at a shallow water
station in the Western Kiel Bight II. Analysis of benthic bacterial populations. Mar. Biol. 77: 247-256.
MORRISON S.J. and D.C. WHITE., 1980. Effects of grazing by estuarine gammaridean amphipods on the
microbiota of allochthonous detritus. Appl. environ. Microbiol. 40:659 -671.
PEINERT R., A. SAURE P. STEGMANN C. STIENEN H. HAARDT and V. SMETACEK., 1982. Dynamics of primary
production and sedimentation in a coastal ecosystem. Neth. J. Sea Res. 16: 276 - 289.
PAMATMAT M. M., 1982. Heat production by sediment : ecological significance. Science, N. Y. 215 : 395-397.
59
Resuspended sediment, terrestrial material and eroded macrophytes represent an additional food supply for the benthic community during winter (Fig. 1). Although heat
production continuously decreased, a high level of benthic biomass accumulated. This
applies for bacterial biomass as well (Fig. 2). The high bacterial biomass sustained during
winter is surprising taking into account the low temperature and the reduced metabolic
activity rates. However, limited number of grazers and the relatively long time the
bacteria had available for their “undisturbed” development may explain the biomass
accumulation. Additionally, the more refractory kind of food source could have been
responsible for the slow, continuous increase in bacterial biomass in winter. In this
respect, the development of the bacterial population in winter differed basically from its
spontaneous development in autumn and spring, respectively.
Fauna development
Additional samples taken in late spring revealed that the further fate of the bacterial
community was greatly influenced by the development of the benthic fauna (data not
shown ; Meyer-Reil 1983). A mass occurrence of polychaetes in the sediment was accompanied by a high number of almost exclusively small-size bacteria (volume <0,3µm3)
which actively grew (high number of dividing cells). Most likely preferentially grazing of
medium and large-size cells by the polychaetes was the reason for the impoverishment of
the bacterial population.There is indeed evidence from the literature that grazing stimulates bacterial activity (Morrison and White, 1980).
CONCLUSION
From the foregoing discussion it becomes obvious that processes like sedimentation and
input of organic material into the sediment may occur in very short time scales (within
days), causing an immediate response of benthic activities. Whereas the succession of
certain processes in the benthic community could be explained by the interactions
between individual parameters, other processes still need explanation. This applies
especially to the decline of benthic activities and biomass after certain levels were reached.
Control mechanisms, such as the growth limiting effect of certain population densities
and interactions between the individual components of the benthic communities, have to
be considered.
GRAF G., R. SCHULZ, R. PEINERT and L.-A. MEYER-REIL., 1983. Benthic response to sedimentation events
during autumn to spring at a shallow water station in the Western Kiel Bight I. Analysis of processes on a
community level. Mar. Biol. 77 : 235 - 246.
HARGRAVE B.T., 1980. Factors affecting the flux of organic matter to sediments in a marine bay. In : K.R.
Tenore and B.C. Coull (Eds.) Marine benthic dynamics. Columbia : Univ. South Carolina Press : 243-263.
MEYER-REIL L.-A., 1983. Benthic response to sedimentation events during autumn to spring at a shallow water
station in the Western Kiel Bight II. Analysis of benthic bacterial populations. Mar. Biol. 77: 247-256.
MORRISON S.J. and D.C. WHITE., 1980. Effects of grazing by estuarine gammaridean amphipods on the
microbiota of allochthonous detritus. Appl. environ. Microbiol. 40:659 -671.
PEINERT R., A. SAURE P. STEGMANN C. STIENEN H. HAARDT and V. SMETACEK., 1982. Dynamics of primary
production and sedimentation in a coastal ecosystem. Neth. J. Sea Res. 16: 276 - 289.
PAMATMAT M. M., 1982. Heat production by sediment : ecological significance. Science, N. Y. 215 : 395-397.
59