Feeding ecology of Limnoperna fortunei in southern China: insights from stable isotopes and fatty-acid biomarkers

Figures & data

Figure 1. Sampling site (23°08′12″ N, 112°48′7″ E) locating at the Xijiang River is about 140 kilometres from seaport. The Xijiang River cover a full distance of over 2214 kilometres.

Table 1. Fatty acids as biochemical markers of certain taxonomic groups that occur in the Xijiang River, southern China. SFAs, MUFAs, PUFAs and BrFAs refer to saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids and branched fatty acids, respectively. DHA refers tor C22:6(n-3) and EPA refers to C20:5(n-3).

Group	Fatty acid markers	References
Chlorophyceae	C18:2(n-6); C18:3(n-3); C16 PUFAs n-3 and n-6	Viso and Marty 1993
		Napolitano 1999
		Petkov and Garcia 2007
Cryptophyceae	Simultaneous occurrence of C18:3(n-3) and C18:4(n-3); C20:5(n-3); C22:6(n-3)	Desvilettes et al. 1997
		Dijkman and Kromkamp 2006
		Brett et al. 2009
		Guevara et al. 2011
Dinophyceae	C18:4(n-3); C22:6(n-3); C16:1(n-7)/C16:0 < 1; DHA/EPA > 1	Napolitano 1999
		Bergé and Barnathan 2005
		Zhao et al. 2013
Bacillariophyceae	C16 PUFAs n-4; C16:1(n-7)/C16:0 > 1; DHA/EPA < 1	Shin et al. 2000
		Dijkman and Kromkamp 2006
		Prato et al. 2012
		Zhao et al. 2013
Cyanobacteria	C18:3(n-3) or 18:3(n-6)	Gugger et al. 2002
Heterotrophic bacteria	BrFAs 15-17 and C18:1(n-7)	Napolitano 1999
		Green and Scow 2000
Decomposed material	C18:0	Hama 1999
Plant detritus particle	C20 and C22 SFAs	Shorland 1963
		Napolitano 1999
Copepoda	C20 and C22 MUFAs	Hagen 1993
		Kattner et al. 2007
Terrestrial organic matter	∑C18:2(n-6) + C18:3(n-3) > 2.5	Zhao et al. 2013

Table 2. δ¹³C values (‰) for the plankton, POM, SOM and L.fortunei tissues in the Xijiang River between March and November in 2014. POM, particulate organic matter; SOM, sediment organic matter. δ¹³C values (‰) are means ± SD (n = 3).

	Plankton	POM	SOM	L.fortunei
Mar	−21.74(0.40)	−20.99(0.26)	−22.87(0.25)	−19.81(0.06)
Apr	−23.38(0.43)	−22.14(0.51)	−22.65(0.30)	−20.87(0.03)
May	−21.81(0.70)	−21.05(0.25)	−26.17(0.21)	−20.38(0.11)
Jun	−22.86(0.34)	−23.52(0.56)	−26.72(0.20)	−21.62(0.18)
Jul	−20.68(0.71)	−23.97(0.47)	−22.88(0.22)	−21.56(0.23)
Aug	−20.87(0.45)	−23.55(0.60)	−21.92(0.20)	−21.59(0.16)
Sep	−21.46(0.54)	−21.92(0.30)	−19.30(0.23)	−19.83(0.03)
Oct	−22.21(0.44)	−21.75(0.21)	−20.36(0.18)	−19.91(0.24)
Nov	−20.77(0.79)	−21.64(0.28)	−19.63(0.21)	−19.39(0.15)

Figure 2. Contributions (%) of plankton, particulate organic matter (POM) and sediment organic matter (SOM) to the diet of L.fortunei in the Xijiang River between March and November 2014.

Table 3. Fatty acid profiles (%) of plankton, POM, SOM and L.fortunei in the Xijiang River (mean ± SD, n = 3). Values indicate concentration (%), while ‘n.d’ and ‘tr.’ mean non-detected and trace, respectively. Fisher's LSD test was used to compare the fatty acids indicated in bold among samples; values labelled with the same letter are not significantly different (P < 0.05). POM, particulate organic matter; SOM, sediment organic matter. SFAs, saturated fatty acids; MUFAs, monounsaturated fatty acids; PUFAs, polyunsaturated fatty acids; BrFAs, branched fatty acids.

Fatty acid	Plankton	POM	SOM	L.fortunei
C14:0	13.64 (1.08) b	5.10 (0.23) c	6.53 (0.52) cd	2.10 (0.07) hi
C15:0	0.85 (0.12)	1.15 (0.06)	0.91 (0.34)	0.57 (0.03)
C16:0	12.38 (0.85) c	24.52 (1.46) a	22.65 (2.80) a	28.92 (1.14) a
C17:0	0.62 (0.09)	1.91 (0.35)	7.69 (1.03)	1.41 (0.20)
C18:0	7.96 (1.32) d	4.83 (0.71) cd	7.86 (1.41) c	2.36 (0.35) gh
C20:0	2.07 (0.21) hij	3.35 (0.93) ef	2.72 (0.40) fghi	0.32 (0.06) j
C22:0	0.36 (0.09)	0.80 (0.23)	1.37 (0.51)	n.d.
∑SFAs	37.88 (2.68)	41.66 (2.27)	49.73 (3.84)	35.68 (1.36)
C14:1(n-5)	0.45 (0.02)	n.d.	n.d.	n.d.
C16:1(n-5)	0.33 (0.04)	n.d.	n.d.	0.18 (0.02)
C16:1(n-7 + n-9)	16.88 (0.57) a	9.75 (0.36) b	10.83 (0.69) b	5.73 (0.20) d
C17:1(n-9)	n.d.	n.d.	n.d.	0.31 (0.06)
C18:1(n-5)	0.15 (0.02)	n.d.	n.d.	0.23 (0.05)
C18:1(n-7)	1.91 (0.07) ij	4.08 (0.25) cde	2.75 (0.42) fgh	5.69 (1.35) d
C18:1(n-9)	1.52 (0.13) jk	10.55 (0.62)b	2.31 (0.58) ghij	5.30 (1.21) de
C20:1(n-7)	0.18 (0.05)	n.d.	n.d.	0.57 (0.14)
C20:1(n-9)	0.62 (0.15) k	1.74 (0.35)gh	0.85 (0.25) jk	2.65 (0.37) gh
C22:1(n-9)	4.15 (0.62) f	3.87 (1.28)de	5.11 (0.95) de	0.87 (0.26) ij
C22:1(n-11)	n.d.	n.d.	n.d.	0.39 (0.12)
∑MUFAs	26.19 (1.75)	29.99 (1.86)	21.85 (2.16)	21.92 (1.25)
C16:2(n-4)	1.95 (0.12) ij	1.50 (0.37) gh	0.60 (0.30) jk	0.45 (0.02) j
C16:3(n-3)	1.36 (0.06)	tr.	tr.	0.81 (0.19)
C16:3(n-4)	2.20 (0.42) hij	1.60 (0.21) gh	1.80 (0.42) ghij	tr.
C16:4(n-3)	1.25 (0.12)	0.80 (0.15)	1.05 (0.11)	n.d.
C18:2(n-4)	0.24 (0.05)	n.d.	n.d.	0.19 (0.01)
C18:2(n-6)	3.03 (0.29) gh	1.95 (0.40) gh	1.02 (0.58) hijk	4.16 (1.43) ef
C18:3(n-3)	3.73 (0.09) fg	1.68 (0.57) gh	0.97 (0.30) ijk	1.04 (0.35) ij
C18:3(n-6)	0.33 (0.05)	n.d.	n.d.	0.25(0.01)
C18:4(n-3)	1.78 (0.23) ij	2.60 (0.25) fg	n.d.k	3.49 (0.36) fg
C20:2(n-6)	0.43 (0.02)	0.53 (0.10)	tr.	0.35 (0.03)
C20:2(n-9)	0.27 (0.08)	n.d.	n.d.	0.35 (0.04)
C20:3(n-3)	n.d.	n.d.	n.d.	0.18 (0.03)
C20:3(n-6)	0.15 (0.02)	n.d.	n.d.	0.23 (0.02)
C20:4(n-3)	0.51 (0.03)	n.d.	n.d.	0.77 (0.08)
C20:4(n-6)	2.01 (0.62) ij	0.84 (0.39) h	1.58 (0.65) hijk	4.65 (1.17) def
C20:5(n-3)	5.23 (0.39) e	4.72 (0.51) cd	3.37 (1.40) fg	7.35 (0.76) c
C22:3(n-9)	n.d.	n.d.	n.d.	0.58 (0.05)
C22:4(n-6)	n.d.	n.d.	n.d.	0.15 (0.02)
C22:5(n-3)	0.28 (0.07)	0.67 (0.31)	n.d.	0.55 (0.12)
C22:5(n-6)	n.d.	n.d.	n.d.	0.21 (0.07)
C22:6(n-3)	2.68 (0.11) hi	1.75 (0.68) gh	0.84 (0.15) jk	9.43 (0.29) b
∑PUFAs	27.43 (1.72)	18.64 (2.23)	1.23 (0.93)	33.93 (2.40)
14-iso	0.32 (0.06)	n.d.	1.60 (0.45)	0.19 (0.04)
14-antiiso	0.20 (0.08)	n.d.	0.95 (0.40)	0.37 (0.12)
15-iso	0.15 (0.01)	0.55 (0.12)	3.37 (0.55)	0.28 (0.05)
16-iso	0.42 (0.15)	0.36 (0.10)	2.11 (0.30)	1.39 (0.22)
16-antiiso	0.15 (0.01)	0.47 (0.31)	1.38 (0.50)	0.31 (0.06)
17-iso	1.21 (0.30) jk	3.52 (0.20) ef	4.23 (0.80) ef	0.47 (0.05) j
∑BrFAs	2.45 (0.37)	4.90 (1.65)	13.64 (2.43)	3.01 (1.02)
Total	93.95 (2.91)	95.19 (3.23)	96.45 (3.85)	94.54 (2.45)

Figure 3. Fatty acid biomarkers in plankton, POM, SOM and in L.fortunei tissues in the Xijiang River. a, Chlorophyceae; b, Cryptophyceae; c, Dinophyceae; d, Bacillariophyceae; e, Cyanobacteria; f, heterotrophic bacteria; g, plant detritus particle; h, Copepoda. Column shading: white, plankton; grey, POM; diagonal, SOM; cross-hatch, L.fortunei, tissues.

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