Natural Variability of Skeletal Elemental Phosphorus (P/Ca), Lead (Pb/Ca), and Barium (Ba/Ca) in the Western Pacific Sclerosponges Acanthoceatetes wellsi and Astrosclera welleyana
Natural Variability of Skeletal Elemental Phosphorus (P/Ca), Lead (Pb/Ca), and Barium (Ba/Ca) in the Western Pacific Sclerosponges Acanthoceatetes wellsi and Astrosclera welleyana
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西太平洋硬海绵动物 Acanthoceatetes Wellsi 和 Astrosclera Welleyana 骨骼元素磷 (P/Ca)、铅 (Pb/Ca) 和钡 (Ba/Ca) 的自然变异
DOI：
10.1029/2020gc009245
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Olesik, John W.
中科院分区：
文献类型：
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作者：
Grottoli, Andréa G.;Chapron, Leila;Gava, Dana;Olesik, John W.
元素代用品被用来重建现代记录之前的海洋条件。这种代理已建立在珊瑚，但很少有人尝试在sclerosponges。然而，它们广泛的分布和缓慢的增长使sclerosponges很好的候选人多世纪记录当地的海洋条件。在这里，我们调查了元素P，Pb和Ba（标准化为Ca）的两个硬海绵物种，Acanthocheates wellsi（高镁方解石）收集于帕劳和塞班岛，和Astroclera willeyana（文石）收集在塞班岛的增生骨架。所有的标本都被原位染色，并在珊瑚礁上生长了两年。我们测量了这些元素（1）2年的散装骨骼样本，以探索当地环境条件和矿物学对骨骼成分的影响，（2）以高分辨率确定这些元素的时间变化并评估其作为古替代物的潜力。我们发现，对于A。wellsi，散装P/Ca较高，铅/Ca较低，在帕劳比塞班岛，这表明这些元素的变化，在响应当地的海水元素组成。在塞班岛，A.对A. willeyana，这很可能是由于矿物学的差异。在高分辨率下，只有P/Ca的签名似乎是适度的重复性内和物种之间的sclerosponges记录海水P/Ca。在塞班岛，A. willeyanaP/Ca的变化也与温度相关，表明海水P浓度的变化与温度共变。需要进一步的研究，以确定是否sclerosponge P/Ca是海水营养变化的可靠代理。
Elemental proxies are used to reconstruct oceanic conditions that predate modern records. Such proxies have been established in corals, but few attempts have been made in sclerosponges. However, their wide distribution and slow growth make sclerosponges good candidates for multicentury recorders of local oceanographic conditions. Here, we investigated the elements P, Pb, and Ba (standardized to Ca) in the accretionary skeleton of two sclerosponge species,Acanthocheatetes wellsi(high‐Mg calcite) collected from Palau and Saipan, andAstrosclera willeyana(aragonite) collected in Saipan. All specimens were stained in situ and left to grow on the reef for two years. We measured these elements in (1) 2‐year bulk skeletal samples to explore the effect of local environmental conditions and mineralogy on the skeletal composition and (2) at high resolution to determine the temporal variability of these elements and evaluate their potential as paleo‐proxies. We found that forA. wellsi, bulk P/Ca was higher and Pb/Ca lower in Palau than in Saipan suggesting that these elements vary in response to the local seawater elemental composition. In Saipan, bulk P/Ca was higher inA. wellsicompared toA. willeyana, which is most likely due to differences in mineralogy. At high resolution, only P/Ca signatures appeared to be moderately reproducible within and among species suggesting that sclerosponges are recording seawater P/Ca. In Saipan,A. willeyanaP/Ca variability also correlated with temperature suggesting that variation in seawater P concentrations co‐varied with temperature. Additional study is needed to determine if sclerosponge P/Ca is a reliable proxy of seawater nutrient variability.