期刊
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
卷 496, 期 -, 页码 32-47出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.palaeo.2017.12.038
关键词
Giant clams; Culture; Trace metals; Diurnal rhythm; Light dependence
资金
- Kirsty Brown Memorial Fund (RHUL)
- University of London
- SRIF3 (HEFCE)
- NERC [NERC CC073]
- EU [FP7-PEOPLE-ITN-2008-237922 THROUGHFLOW]
- Israel Science Foundation [551/10]
Recent advances in spatially-resolvedin-situ geochemical analysis enabled recognizing daily variability in B, Mg, Sr and Ba within bivalve shells of the genus Tridacna (e.g. Sano et at, 2012; Warter and Muller, 2017). However, the causes for such daily chemical variations are not fully understood. We carried out laboratory culture experiments to investigate the effect of varying temperatures and light levels on organism physiology and shell geochemistry of the giant clam Tridacna crocea at daily time-resolution. We find that both temperature and light strongly influence shell growth rates. Besides demonstrating light enhanced calcification, we also observe growth inhibition during culture in continuous darkness. 'Ultra-high resolution' LA-ICP-MS analysis (Warter and Miller, 2017) in tandem with Ba-135-labelling allows both to identify newly secreted, cultured aragonite and investigate its trace elemental composition at (sub)daily resolution (B/Ca, Mg/Ca, Sr/Ca, Ba/Ca). Overall, average Element/Calcium (El/Ca) ratios reveal an inverse relation with temperature and light. Strikingly, an increasing trend in all El/Ca ratios is observed in the direction of shell growth, which is interpreted to be metabolically-controlled, possibly related to organism 'stress'. Daily, cyclic trace element variability can be clearly resolved at similar to 5-15 mu m in relatively fast growing shells, which experienced a diurnal light cycle but constant temperatures. We conclude that light (but not temperature) is the primary controlling factor responsible for daily trace element variability. We further demonstrate that high El/Ca ratios correspond to growth during night time, i.e. low light intensities, corroborating field observations by Sano et al. (2012). Yet, because light levels were kept constant during night and day, respectively, light intensity cannot account for the entire range of the El/Ca variability. We hypothesize that Tridacna physiology and biochemistry is controlled by a circadian rhythm, initiated by the external factor light, but endogenously mediated by the giant clam and/or its photosynthetic symbionts.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据