Senckenberg am Meer, Abteilung Meeresforschung, Südstrand 40, 26382 Wilhelmshaven, Germany.
GeoZentrum Nordbayern, Fachgruppe Paläoumwelt, Universität Erlangen-Nürnberg, Loewenichstraße 28, 91054 Erlangen, Germany.
PLoS One. 2015 Apr 20;10(4):e0126495. doi: 10.1371/journal.pone.0126495. eCollection 2015.
The effects of water depth, seasonal exposure, and substrate orientation on microbioerosion were studied by means of a settlement experiment deployed in 15, 50, 100, and 250 m water depth south-west of the Peloponnese Peninsula (Greece). At each depth, an experimental platform was exposed for a summer period, a winter period, and about an entire year. On the up- and down-facing side of each platform, substrates were fixed to document the succession of bioerosion traces, and to measure variations in bioerosion and accretion rates. In total, 29 different bioerosion traces were recorded revealing a dominance of microborings produced by phototrophic and organotrophic microendoliths, complemented by few macroborings, attachment scars, and grazing traces. The highest bioerosion activity was recorded in 15 m up-facing substrates in the shallow euphotic zone, largely driven by phototrophic cyanobacteria. Towards the chlorophyte-dominated deep euphotic to dysphotic zones and the organotroph-dominated aphotic zone the intensity of bioerosion and the diversity of bioerosion traces strongly decreased. During summer the activity of phototrophs was higher than during winter, which was likely stimulated by enhanced light availability due to more hours of daylight and increased irradiance angles. Stable water column stratification and a resulting nutrient depletion in shallow water led to lower turbidity levels and caused a shift in the photic zonation that was reflected by more phototrophs being active at greater depth. With respect to the subordinate bioerosion activity of organotrophs, fluctuations in temperature and the trophic regime were assumed to be the main seasonal controls. The observed patterns in overall bioeroder distribution and abundance were mirrored by the calculated carbonate budget with bioerosion rates exceeding carbonate accretion rates in shallow water and distinctly higher bioerosion rates at all depths during summer. These findings highlight the relevance of bioerosion and accretion for the carbonate budget of the Ionian Sea.
本研究通过在希腊伯罗奔尼撒半岛西南 15、50、100 和 250 米水深处进行的沉降实验，研究了水深、季节性暴露和基质方位对微生物侵蚀的影响。在每个深度，实验平台都暴露了一个夏季、一个冬季和大约一整年。在每个平台的迎流面和背流面，固定了基质以记录生物侵蚀痕迹的演替，并测量生物侵蚀和堆积速率的变化。总共记录了 29 种不同的生物侵蚀痕迹，这些痕迹主要是由光养和有机养微层孔虫产生的微钻孔，辅以少量的宏观钻孔、附着痕迹和放牧痕迹。在浅光区的 15 米迎流面基质上，生物侵蚀活性最高，主要由光养蓝细菌驱动。在以绿藻为主的深光区到弱光区和以有机营养为主的无光区，生物侵蚀的强度和生物侵蚀痕迹的多样性都强烈下降。夏季光养生物的活动比冬季高，这可能是由于白天时间更长、辐照度角度增加导致光照可用性增强而刺激的。稳定的水柱分层和浅水中营养物质的耗尽导致浊度水平降低，并导致光区发生变化，反映出更多的光养生物在更大的深度活跃。对于有机营养生物的次要生物侵蚀活性，温度和营养状况的波动被认为是主要的季节性控制因素。生物侵蚀率超过碳酸盐堆积率，在浅水区生物侵蚀率明显更高，夏季所有深度的生物侵蚀率都明显更高，这与总体生物侵蚀者分布和丰度的观测模式相吻合。这些发现强调了生物侵蚀和堆积对爱奥尼亚海碳酸盐预算的重要性。
