. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SYMBIONT POPULATIONS IN SEEP AND VENT MUSSELS 153 for B. azoricus and B. puteoserpentis from Mid-Atlantic Ridge vents are positively related to the ratio of CH4 to H2S in the end-member fluids (Fig. 7). Ratios of methanotrophs to chemoautotrophs are so far reported only for B. a-oricus from Lucky Strike and Menez Gwen (Trask and Van Dover, 1999; Fiala-Medioni el ai, 2002; this study) and for B. heckerae from the Blake Ridge seep (this study), and are consistent with the model of increasing density of meth- anotrophs as the r
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SYMBIONT POPULATIONS IN SEEP AND VENT MUSSELS 153 for B. azoricus and B. puteoserpentis from Mid-Atlantic Ridge vents are positively related to the ratio of CH4 to H2S in the end-member fluids (Fig. 7). Ratios of methanotrophs to chemoautotrophs are so far reported only for B. a-oricus from Lucky Strike and Menez Gwen (Trask and Van Dover, 1999; Fiala-Medioni el ai, 2002; this study) and for B. heckerae from the Blake Ridge seep (this study), and are consistent with the model of increasing density of meth- anotrophs as the ratio of CH4 to H2S increases (Fig. 7). The relationships in Figure 7 are intriguing, but low-temperature fluid chemistry, symbiont densities, and isotopic composi- tions of fluids and host mussel tissues remain to be deter- mined in a systematic manner across a range of CH4:H2S values for any given species. These relationships should ultimately prove powerful in the analysis of energy flow in dual-symbiont mussel systems. Tissues from B. heckerae were consistently more en- riched in !>N than tissues from B. azoricits. Lacking any CO I o CD CD O- CO CO (J CO JJ £5 CD (D N CD C CD CD CQ O .0 C '(0 CE £ Q. CD CD CO cr _ra CQ CQ CO 01 o ft Chemoautotrophs dominant 5^ -10 -15- -25 -30 -35-I Methanotrophs dominant » -40. Q. Q. Q 2 11 ™ 2 £ o 5 E ^ CD jr O 01234 CH4:H2S (end-member fluid) Figure 7. Relationship between the 8i:>C of source methane, the 8"C of mussel gill tissue, the ratio of methanotrophs to chemoautotrophs in gill bacteriocytes of mussels (identified as Bp: Bathymodiolus puteoserpentis; Ba = B. azoricus: Bli = B. heckerae}, and the ratio of methane to sulfide (CH4:H,S) in end-member fluids of vent sites. CH4:H2S for seep porewater is indicated by the dotted vertical line. Sites are identified at the top of the figure. Line A: 8nCgM = (CH4:H2S)—36%0; r = Line B: Ratio of methanotrophs to chemoautotrophs = (CH4:H,
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
