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

Seasonal variations in bacterial populations (total number, biomass, biomass-spectrum, number of dividing cells) as well as in concentrations and decomposition rates of particulate organic material were followed in a sandy mud sediment of the Western Kiel Bight (Baltic Sea; FRG). The strong seasonal variations observed could be traced back to the effect of certain ecological situations and events in the sediment from which the input of the phytoplankton blooms in autumn and spring, respectively, the accumulation of organic material during winter, and the spring development of the benthic fauna turned out to be the most important. Bacterial carbon net production following the breakdown of the phytoplankton blooms ranged between 9 μg (autumn) and 16 μg (spring) per g of dry weight sediment per day. The consequences of shifts in the size composition of the bacterial populations as well as the importance of the measurement of enzymatic decomposition rates of particulate organic material in sediments are demonstrated and discussed in relation to the events mentioned abov

Enzymatic decomposition of proteins and carbohydrates in marine sediments : methodology and field observations during spring

Microbial biomass, concentrations and enzymatic decomposition rates of proteins and carbohydrates were analysed during spring 1980 from a 10 m sediment station in the Kiel Bight. During March, a considerable increase in total organic matter, proteins and carbohydrates was observed, followed by a decrease during April. The accumulation of organic matter in the sediment could be traced back to the breakdown of the algal spring bloom. Activity rates of (α-amylase, ß-D-glucosidase and proteolytic enzymes paralleled the variation pattern in concentrations of carbohydrates and proteins. During the decomposition processes, a drastic shift in the protein to carbohydrate ratio was observed. The dominating part of the enzymes involved in the decomposition of organic material obviously arose from autolysis of the algae cells themselves. After an initial depression, microbial biomass increased, obviously due to the availability of suitable substrates for microbial growth following the decomposition processes

An improved method for the semicontinuous culture of bacterial populations of Nuclepore membrane filters

The present paper describes an improved method for the semicontinuous culture of bacterial populations on Nuclepore membrane filters. The filters, placed on swimming rings, are incubated in direct contact with the water surface of the flow system, and examined by fluorescence microscopy. The growth activity of both, pure cultures and natural bacterial populations, measured in the flow system is compared to the activity measured in a conventional culture system (incubation of membrane filters on the surface of paper disc saturated with incubation medium). The flow system increases the number and the spectrum of colony forming cells. The reasons for the superiority of the flow system are discussed

A new method for fluorescence staining of bacterial populations on membrane filters

This article describes and discusses a new method for the fluorescence microscopic examination of bacteria on Nuclepore membrane filters. The bacteria, which have been concentrated by filtration, are stained with a solution of acridine orange. Then the filters are destained with isopropyl alkohol and xylene. This method makes it possible to recognize small bacteria and to distinguish them from detritus. Dieser Beitrag beschreibt und diskutiert eine neue Methode zur fluoreszenzmikroskopischen Untersuchung von Bakterien auf Nuclepore-Membranfiltern. Die durch Filtration angereicherten Keime werden mit einer Akridinorange-Lösung gefärbt. AnschlieBend werden die Filter mit Isopropanol und Xylol entfärbt. Diese Methode ermöglicht es, auch kleine Bakterien zu erkennen und sie von Detritus zu unterscheiden

Benthic response to sedimentation events during autumn to spring at a shallow-water station in the Western Kiel Bight

The response of the benthos to the break up of anoxia in the Kiel Bight (Western Baltic Sea), and to three succeeding events of “external” food supply, consisting of a settled autumn plankton bloom, resuspended matter and macrophyte input during winter, and of a sedimented spring phytoplankton bloom, is described on a community level. The first input of oxygen broke up anoxic conditions and made stored food resources available to decomposition. This “internal” food supply, mainly consisting of protein (folin positive matter), was followed by a drastic increase in heat production and ATP-biomass and caused a period of low redox potential, which lasted for several weeks. During this phase, a plankton bloom (dinoflagellates and diatoms) settled to the sea floor. Although there was an immediate response of benthic activity, this food input was not completely consumed by the strongly disturbed benthic community. During winter resuspended matter and the input of macrophyte debris caused another maximum in benthic activity and biomass despite the low temperature. The response to sedimentation of cells from a diatom bloom during mid March was also without any time lag and was consumed within 5–6 wk. A comparison of the amount of particles collected in a sediment trap with the increase of organic matter in the sediment demonstrated that the sediment collected four times (autumn) and seven to eight times (spring) more than measured by the sediment trap. Strong indications of food limitation of benthic activity were found. During autumn and winter these indications were caused more by physical than by biological processes. The three events of “external” food supply caused a temporary shift in the type of metabolism towards fermentation processes and reduced the redox potential. In spring the development of the benthic community was still being strongly influenced by the events of the preceding summer and autumn