Dark CO₂ fixation into phospholipid-derived fatty acids by the cold-water coral associated sponge Hymedesmia (Stylopus) coriacea (Tisler Reef, NE Skagerrak)

Figures & data

Figure 1. In-situ benthic community with the coral Lophelia pertusa (white polyps) and the orange coral associated sponge Hymedesmia (Stylopus) coriacea overgrowing the coral (arrow is pointing to several coral polyps overgrown by the sponge).

Figure 2. Incubation cylinder with Hymedesmia (Stylopus) coriacea growing encrusting over branches of the cold-water coral Lophelia pertusa. Hymedesmia (Stylopus) coriacea has a light orange to light brown colour.

Table 1. Overview of sponge experiments conducted in cylinder incubation chambers (CY). Sponges in series CYa, CYb and CYc were incubated with ¹³C-DIC. To ten sponges (shaded in table) also 100 μM (NH₄)₂SO₄ was added. Sponge with orange numbers (codes CY8-4, CY9-12, CY6-21) did not incorporate measureable amounts of ¹³C in bulk sponge tissue (see results CO₂ fixation rates).

Cylinder incubation chamber experiments	Series CYa	Series CYb	Series CYc
^13C-DIC concentration	600 μM	600 μM	900 μM
incubation time	63 h	44 h	38 h
Cylinder CY5	1	8	20
CY6	2	9	21
CY7	3	10	22
CY8	4	11	23
CY9	5	12	24
CY10	6	13	25

Table 2. Concentrations of variables (with standard deviations) of In-situ water from Tisler reef (collected on 3 September 2010) and the Bay of Tjärnö (collected between 25 August and 10 September 2010). Bay of Tjärnö water was used for the incubations. DIC = dissolved inorganic carbon, TOC = total organic carbon, DOC = dissolved organic carbon.

Variable		Tisler Reef water from 123 m depth		Bay of Tjärnö supply water from 45 m depth
	n		n
DIC (μM)	2	2216 (6)	7	2146 (23)
TOC (μM)	2	81 (3)	14	126 (73)
DOC (μM)	2	85 (3)	12	112 (28)
PO4 (μM)	2	0.67 (0.01)	18	0.47 (0.08)
NH3 (μM)	2	0.21 (0.04)	18	0.30 (0.20)
NOx (μM)	2	7.56 (0.01)	18	5.51 (0.92)
NO2 (μM)	2	0.23 (0.002)	18	0.10 (0.02)
prokaryotes
(n*10^6 × ml^−1)	2	5.4 (0.4)	16	3.9 (0.2)

Table 3. DIC fixation by Hymedesmia (Stylopus) coriacea with and without ammonium sulfate addition in cylinder (CY) and pulse-chace (PC) experiments with standard deviations.* Rate calculation made 3 days after pulse was removed, assuming that the ¹³C was only incorporated during pulse period.

	Additions in μM	n	Bulk total C-DIC fixation
	(NH4)SO4		μg × gDWsp^−1 × d^−1	μmol × mmol Csp^−1 × d^−1
CY experiments	0	7	21.69 ± 3.91	0.052 ± 0.011
CY experiments	100	8	20.08 ± 11.96	0.044 ± 0.025
PC experiment	200	1	32.54	0.069
PC experiment*	200	2	34.28 ± 2.83	0.073 ± 0.001

Figure 3. Relation between sponge tissue fixation of ¹³C-DIC and ¹³C-DIC concentration with and without added ammonium sulfate. Linear regression lines are shown.

Figure 4. Changes in sponge bulk tissue ¹³C-enrichment after a pulse of ¹³C-labelled sodium bicarbonate (2353 μM ¹³C-DIC).

Figure 5. PLFA’s with equivalent chain length of less than 25 carbon atoms of pure tissue samples of the sponge Hymedesmia (Stylopus) coriacea in sample CY8-11. (a) Concentrations of PLFA’s. (b) Contribution (%) of ¹³C in PLFA’s after 44 h incubation with ¹³C-DIC.

Figure 6. PLFA results with equivalent chain lengths up to 29C-atoms of coral contaminated samples of the sponge Hymedesmia (Stylopus) coriacea. (a) Concentration of PLFA’s. (b) Contribution (%) of ¹³C in PLFA’s after 44-63 h incubation with ¹³C-DIC. For colour explanation of PLFA’s see Figure 5a.

Figure 7. Temporal changes in ¹³C enrichment of PLFA’s of coral contaminated sponge samples of Hymedesmia (Stylopus) coriacea after a ¹³C-DIC pulse, which was removed 49 h after start of the pulse chase experiment. Concentration in ng C derived from DIC × g DW_ccsp⁻¹ comprises ¹²C and ¹³C-DIC incorporated. (a) Bacteria-specific PLFA’s and C16:1ω7. (b) Saturated short chain PLFA’s (max 20 C-atoms chain lengths). (c) Mono- and poly-unsaturated PLFA with equivalent chain lengths of 18–25 carbon atoms. (d) Very long chain PLFA’s with equivalent chain lengths of 25 or more carbon atoms.