Seasonal variations in surface metabolite composition of Fucus vesiculosus and Fucus serratus sampled at outer Kiel Fjord (August 2012 - July 2013)

The chemical composition of surface associated metabolites of two Fucus species (Fucus vesiculosus and Fucus serratus) was analysed by means of gas chromatography-mass spectrometry (GC-MS) to describe temporal patterns in chemical surface composition. Method: The two perennial brown macroalgae F. vesiculosus and F. serratus were sampled monthly at Bülk, outer Kiel Fjord, Germany (54°27'21 N / 10°11'57 E) over an entire year (August 2012 - July 2013). Per month and species six non-fertile Fucus individuals were collected from mixed stands at a depth of 0.5 m under mid water level. For surface extraction approx. 50 g of the upper 5-10 cm apical thalli tips were cut off per species. The surface extraction of Fucus was performed according to the protocol of de Nys and co-workers (1998) with minor modifications (see Rickert et al. 2015). GC/EI-MS measurements were performed with a Waters GCT premier (Waters, Manchester, UK) coupled to an Agilent 6890N GC equipped with a DB-5 ms 30 m column (0.25 mm internal diameter, 0.25 mM film thickness, Agilent, USA). The inlet temperature was maintained at 250°C and samples were injected in split 10 mode. He carrier gas flow was adjusted to 1 ml min-1. Alkanes were used for referencing of retention times. For further details (GC-MS sample preparation and analysis) see the related publication (Rickert et al. submitted to PLOS ONE).

(Table 1) Phosphorus and carbon chemistry of ODP Holes 169-1033B and 169-1034B

Uncertainty currently exists about the removal of carbon (C) and phosphorus (P) from the oceanic reservoir, especially in low oxygen settings. In this paper, the cycling of C and P is examined in sediments from the anoxic Saanich Inlet, cored by Ocean Drilling Program (ODP) Leg 169S in 1996 at two sites. Although Corg/Porg ratios are high and increase with depth in the Saanich Inlet, this effect is due largely to a remobilization of P from an organic matter sink to an authigenic sink. Reducible sedimentary components act as temporary shuttles in this process even in this anoxic setting, with the ultimate burial sink for the remobilized P being carbonate fluorapatite. The effective Corg/Preactive molar ratio appears to be about 150-200, indicating some preferential loss of P compared to C during organic matter degradation, but not approaching previously reported values of over 3000 in black shales. Reactive P accumulation rates in this basin range from 10,000-60,000 µmol/cm**2/kyr, greatly exceeding the range of 500-8000 µmol/cm**2/kyr found in most continental-margin settings, including regions of modern phosphogenesis. The initiation of marine sedimentation in the Saanich Inlet occurred after deglaciation, and the high rates of P burial seen here may provide an end-member example of the effects of sea level and margin sedimentation on the distribution of P within the marine P cycle.