The Annual Cycle of Kiel Bight Plankton: A Long-Term Analysis

Abstract

ABSTRA("i: (}~el the past decade, the annual cycle of the major pelagic processes in relation io environ,uenial taciuis and species composition of the plankton has been studied intensively a! a fixed station in Kid Bight. A series of sequential phases, differentiated according to characteristic properties, succeed each other in a recurring pattern each year. The following phases have been differentiated: the spring diatom bloom, the late spring copepod maximum, the summer stratification, the fall blooms and the winter dormancy. Each phase represents a particular pattern of biogenous element cycli~tg, both wilhin the pelagic system and between the pelagic and benthic systems. Each phase is also ch:trat:le~ized by a spectrum of dominant species, many of which do not recur each year. Greatest variatio,, is found amongst bloom diatoms, whereas large, slow-growing species such as the Ceratia and m(~t meta~ot~plankton are highly recurrent. Variation in species composition is not related to I~,g term tremlr~ since the past century, in spite of the considerable increase in anthropogeoic nutrieiit input to the Bight. Short..term events appear to determine occurrence of fast-growing species, luany of which have benthic resting stages in their life histories. It is concluded that more atientioit sllould be paid to life history strategies of species if the mechanisms of seasonal succession are to be elucidated. Long-term observations on appearance or absence of the various species in relation to euvir6nrneotal properties can provide clues as to the nature of these life history strategies. l,llri~ditt.tioiJThe history o[ quaniilatr~,e plankton research goes back a c~;litltry tfJ Hensen's (1887) pionec, iug .,;tudy of plankton standing stock and pruductioii conducted in Kiel Bight (Bay is a synon~qn) liom i 882 to 1885. His intention was to dcv~lo0 a standardized methodology ti~, cslimating the potential food supply of lish iiJ lhe see iii order to establish a scieniitic basis for fisheries regulation. SiIlC(: lheri, illllnerom; investigations have been t;an-icd ~>l~l i~' Ihc Bight that can be grouped into pcliods ac

Seasonal changes and population dynamics of the ctenophore Mnemiopsis leidyi after its first year of invasion in the Kiel Fjord, Western Baltic Sea

“…Gelatinous carnivores peaked later and matched with the peaks of phytoplankton and ciliates. The general annual cycle of the pelagic system of the Kiel Bight is basically similar to the gained data of ours with the diatom spring bloom, the late spring copepod maximum and the summer stratification (Smetacek 1983).…”

Microbial methanogenesis in the sulfate-reducing zone of sediments in the Eckernförde Bay, SW Baltic Sea

“…From mid-March until mid-September the water column is strongly stratified due to the inflow of saltier North Sea water and warmer and fresher surface water (Bange et al, 2011). Organic matter degradation in the deep layers causes pronounced hypoxia (March-September) or even anoxia (August-September; Smetacek, 1985;Smetacek et al, 1984). The source of organic material is phytoplankton blooms that occur regularly in spring (February-March) and fall (September-November) and are followed by the pronounced sedimentation of organic matter (Bange et al, 2011).…”

The annual cycles of phytoplankton biomass

“…These periodic annual cycles are linked to annual fluctuations of mixing, temperature, light and precipitation (Smetacek 1985;Sommer et al 1986;Cloern 1996). Changing climatic conditions can modify these environmental factors and alter phytoplankton annual cycles directly or indirectly by altering resource availability and trophic interactions.…”