Microphytobenthos of Arctic Kongsfjorden (Svalbard, Norway): biomass and potential primary production along the shore line

During summer 2007, Arctic microphytobenthic potential primary production was measured at several stations around the coastline of Kongsfjorden (Svalbard, Norway) at ?5 m water depth and at two stations at five different water depths (5, 10, 15, 20, 30 m). Oxygen planar optode sensor spots were used ex situ to determine oxygen exchange in the overlying water of intact sediment cores under controlled light (ca. 100 ?mol photons m?2 s?1) and temperature (2–4°C) conditions. Patches of microalgae (mainly diatoms) covering sandy sediments at water depths down to 30 m showed high biomass of up to 317 mg chl a m?2. In spite of increasing water depth, no significant trend in “photoautotrophic active biomass” (chl a, ratio living/dead cells, cell sizes) and, thus, in primary production was measured at both stations. All sites from ?5 to 30 m water depth exhibited variable rates of net production from ?19 to +40 mg O2 m?2 h?1 (?168 to +360 mg C m?2 day?1) and gross production of about 2–62 mg O2 m?2 h?1 (17–554 mg C m?2 day?1), which is comparable to other polar as well as temperate regions. No relation between photoautotrophic biomass and gross/net production values was found. Microphytobenthos demonstrated significant rates of primary production that is comparable to pelagic production of Kongsfjorden and, hence, emphasised the importance as C source for the zoobenthos

New Records of Praethecacineta halacari (Schluz) (Suctorea: Ciliophora) from Taiwan, Tanzania and Canada

The present study reports on a range extension of the suctorian species Praethecacineta halacari to the region of He-Ping-Dao, north-east of Taiwan (West Pacific Ocean), Matemwe, the east coast of Unguja, Zanzibar, Tanzania (West Indian Ocean) and Nova Scotia, Canada (West Atlantic Ocean). Praethecacineta halacari is reported here for the first time from Taiwan, Tanzania and Canada. Earlier records include the Caspian Sea, Western Australia, Brazil, India, and various coastal sites in Europe

Impact of phosphorus quota and growth phase on carbon allocation in Chlamydomonas reinhardtii: an FTIR microspectroscopy study

Batch cultures of Chlamydomonas reinhardtii were used to study carbon allocation in relation to growth phase and phosphorus availability. Cultures were grown at initial phosphorus (PO4-P) concentrations of 500 μg l-1 (high-P) and 50 μg l-1 (low-P). Cellular carbon allocation was monitored using Fourier transform infrared (FTIR) microspectroscopy with the ratio of the band intensities at 1736 cm-1 (lipid) and the 1180-950 cm-1 region (carbohydrate) to 1652 cm-1 (amide I) used as an index of changing carbon balance. Cellular phosphorus concentrations (P quota) were measured by energy dispersive X-ray microanalysis (EDXRMA). Both treatments entered stationary phase on day 18. Increased cell counts in the high-P treatment (max. 3.0 × 106 cells ml-1 at stationary phase) led to a rapid decrease in external P availability t