Eine Methode zur Bestimmung des Kaloriengehaltes von Seston

Es wird eine Methode zur Bestimmung des Kaloriengehaltes von partikularer Substanz aus Schöpfer- und Sinkstoffproben beschrieben. Die Proben werden auf Glasfaserfilter (Whatman GF/C, 2,25 cm Durchmesser) oder Membranfilter (Sartorius, Typ SM 1130, 2,5 cm Durchmesser) filtriert. Die Glasfaserfilter mit dem Filterrückstand werden nach Zugabe von Benzoesäure, die in Äthylalkohol gelöst ist, getrocknet und in einem Phillipson-Mikrokalorimeter verbrannt. Bei der Verbrennung der Membranfilter entfällt die Zugabe von Benzoesäure, da die Filter aus explosivem Cellulosenitrat bestehen. Sie können direkt nach der Trocknung verbrannt werden. Der methodische Fehler liegt bei der Verwendung von Glasfaserfiltern bei 27,1% und bei der Verwendung von Membranfiltern bei 9,6%. Als optimal erwies sich die Verwendung von Membranfiltern der PorengroBe 0,8 µ und die zweimalige Spülung des angereicherten Sestons auf dem Filter mit 2 bis 5 ml destilliertem Wasser. Die Glasfaser- und die Membranfilter weisen keinen signifikanten Unterschied in Bezug auf den Kaloriengehalt des abfiltrierten Sestons auf. In Bezug auf den Sestongehalt (als Trockengewicht) zeigt der Glasfaserfilter eine signifikant höhere Retention gegenüber dem Membranfilter (p1 < 2% und p2 < 0,1%). Es ergab sich ein signifikanter Unterschied (p < 0,2% in Bezug auf den Seston- und p < 0,1 % in Bezug auf den Kaloriengehalt) in der Retention der Filter bezogen auf 1 l Wasser bei der Filtration unterschiedlicher Wassermengen (1 l und 2 l). Aus diesem Grunde sollte immer die gleiche Menge Wasser zur Filtration verwendet werden. Der kalorische Aspekt der Phytoplanktonblüte im Frühjahr 1972 vor Boknis Eck wird dargestellt und diskutiert. Der Kaloriengehalt einer Phytoplanktonpopulation kann als Index für deren physiologischen Zustand angesehen werden

An approach to quantify the energy flow through the pelagic part of the shallow water ecosystem off Boknis Eck (Eckernförde Bay)

The energy flow of the pelagic part of a shallow water ecosystem is quantified using measurements of global incident radiation, particulate organic carbon, caloric content of the particulate matter, data from other authors on primary production, zooplankton secondary net production and zooplankton tertiary net production as well as several conversion factors from the literature. - The total potential radiant energy in 1973 amounted to 3.46 · 105 kcal m-2 y-1, the phytoplankton net production to 2.66 · 103 kcal m-2 y-1, with an average transfer efficiency of 0.77%. The zooplankton secondary and tertiary net production were 3.58 · 102 and 5.49 · 101 kcal m-2 y-1 respectively. More than 40% of the phytoplankton net production (1.08 · 103 kcal m-2 y-1) was remineralised within the water column, 35% of the phytoplankton net production (9.25 · 102 kcal m-2 y-1) sedimented directly to the bottom. The total transfer to the sediment amounted to 1.55 · 103 kcal m-2 y-1 (corresponding to 58.3% of the phytoplankton primary production), the further transfer to higher trophic levels was 4.34 · 101 kcal m-2 y-1 or 1.6% of the phytoplankton primary production

Sedimentation of particulate matter during a phytoplankton spring bloom in relation to the hydrographical regime

Data presented and discussed here were collected continuously during April/May 1975 in the Bornholm Basin of the Baltic Sea. Sedimentation rates of particulate matter were recorded with 5 multisample sediment traps from different depths in the water column at 2 positions 170 km apart. Current meter data collected during the same period and depths indicated that the positions remained hydrographically distinct during the investigation. Particulate matter from the euphotic zone including diatom cells formed the bulk of the material collected by all traps. This flux of organic particles to the bottom was unimpeded by the strong density stratification present in the water column. The upper traps always collected less material than lower ones. This paradox has been ascribed to diminishing current speeds with depth, concomitant with an increase in sinking rates of phytoplankton and phytodetritus. Both factors influence the sampling efficiency of sediment traps, which are thought to have underestimated actual sedimentation rates here. A time lag of 2 to 3 weeks in bloom development seemed responsible for the characteristic differences between the two positions. The phase of major sedimentation at one position covered about 18 days, and a distinct sequence in the composition of the material collected by the 6 glasses of each trap indicated phases of a progressively deteriorating phytoplankton population in the water column contributing the particulate material. A total of 6.2 g C m-2 in 34 days was recorded at this station. Apart from a trap situated in an oxygen deficient layer which collected 0.44 g C m-2 of zooplankton corpses, zooplankton mortality was overestimated by the traps. Large-scale sedimencation of “fresh” organic matter produced by the spring bloom is probably a regular feature in areas with low over-wintering zooplankton populations and, as such, possibly has a direct stimulatory effect on growth and reproduction of the benthos

A comparison of moored and free-drifting sediment traps of two different designs

The Kiel conical sediment trap and a 3:1 right cylinder were simultaneously deployed in both free-drifting and moored modes on four separate occasions over the Peruvian shelf in order to compare downward flux measurements derived from each…

Silicate limitation in a filament

We observed variations in primary nutrients and phytoplankton biomass in an upwelling event off Oman during the strong SW-monsoon 1997. A so called filament, originating in the coastal upwelling, was tracked, marked with a drifter and followed for 19 days while intensive water sampling took place. The first stations in this upwelling event showed a severe silicate limitation. With the silicate limitation a diverse diatom community vanished. Although after a couple of days new silicate became available, another phytoplankton community of smaller organisms < 20 flm) with nearly no diatoms bloomed. These results raise fundamental questions about the interactions between silicate limitation and the control of carbon export in the worlds most productive areas. It is discussed, whether these limitation events might be typical short term features of coastal upwelling ecosystems, not described as yet

Growth and sedimentation of the phytoplankton spring bloom in the Borholm Sea (Baltic Sea)

Results obtained from short-term (8 h to 24 h intervals) measurements of physical, chemical and biological properties of the 70 m water column from an anchor station in the Bornholm Sea over a 10-day period are presented and discussed. Phytoplankton biomass concentration and production rates indicated that the spring bloom was in progress in this period. The onset of the spring bloom occurred prior to the advent of thermal stratification. Peak growth rates, accompanied by nutrient depletion and biomass accumulation in surface layers, were concomitant with calm weather and a cloudless sky after which a part of the population was observed to sink out of the water column unimpeded by the permanent halocline. Maximum sinking rates of the dominant species, Skeletonema costatum, ranged between 30 to 50 m per day during this event. The development of the spring bloom apparently takes place in a series of events during which periods of low production alternate with periods of high production and rapid sedimentation of parts of the population

Technical Note: A mobile sea-going mesocosm system - new opportunities for ocean change research

One of the great challenges in ocean change research is to understand and forecast the effects of environmental changes on pelagic communities and the associated impacts on biogeochemical cycling. Mesocosms, experimental enclosures designed to approximate natural conditions, and in which environmental factors can be manipulated and closely monitored, provide a powerful tool to close the gap between single species laboratory experiments and observational and correlative approaches applied in field surveys. Existing pelagic mesocosm systems are stationary and/or restricted to well-protected waters. To allow mesocosm experimentation in a range of hydrographic conditions and in areas considered most sensitive to ocean change, we developed a mobile, sea-going mesocosm facility, the Kiel Off-Shore Mesocosms for Future Ocean Simulations (KOSMOS). The KOSMOS platform, which can be transported and deployed by mid-sized research vessels, is designed for operation in moored and free-floating mode under low to moderate wave conditions (up to 2.5 m wave heights). It encloses a water column 2 m in diameter and 15 to 25 m deep (~50–75 m3 in volume) without disrupting the vertical structure or disturbing the enclosed plankton community. Several new developments in mesocosm design and operation were implemented to (i) minimize differences in starting conditions between mesocosms, (ii) allow for extended experimental duration, (iii) precisely determine the mesocosm volume, (iv) determine air–sea gas exchange, and (v) perform mass balance calculations. After multiple test runs in the Baltic Sea, which resulted in continuous improvement of the design and handling, the KOSMOS platform successfully completed its first full-scale experiment in the high Arctic off Svalbard (78° 56.2′ N, 11° 53.6′ E) in June/July 2010. The study, which was conducted in the framework of the European Project on Ocean Acidification (EPOCA), focused on the effects of ocean acidification on a natural plankton community and its impacts on biogeochemical cycling and air/sea exchange of climate relevant gases. This manuscript describes the mesocosm hardware, its deployment and handling, CO2 manipulation, sampling and cleaning, including some further modifications conducted based on the experiences gained during this study