The Elemental Composition of Demospongiae from the Red Sea, Gulf of Aqaba

Trace elements are vital for the growth and development of all organisms. Little is known about the elemental content and trace metal biology of Red Sea demosponges. This study establishes an initial database of sponge elemental content. It provides the necessary foundation for further research of the mechanisms used by sponges to regulate the uptake, accumulation, and storage of metals. The metal content of 16 common sponge species was determined using ICP measurements. A combination of statistical methods was used to determine the correlations between the metals and detect species with significantly high or low concentrations of these metals. Bioaccumulation factors were calculated to compare sponge metal content to local sediment. Theonella swinhoei contained an extremely high concentration of arsenic and barium, much higher (at least 200 times) than all other species and local sediment. Hyrtios erecta had significantly higher concentration of Al, Cr, Fe, Mn, Ti and V than all other species. This is due to sediment accumulation and inclusion in the skeleton fibers of this sponge species. Suberites clavatus was found to contain significantly higher concentration of Cd, Co, Ni and Zn than all other species and local sediment, indicating active accumulation of these metals. It also has the second highest Fe concentration, but without the comparably high concentrations of Al, Mn and Ti that are evident in H. erecta and in local sediment. These differences indicate active uptake and accumulation of Fe in S. clavatus, this was also noted in Niphates rowi. A significantly higher B concentration was found in Crella cyatophora compared to all other species. These results indicate specific roles of trace elements in certain sponge species that deserve further analysis. They also serve as a baseline to monitor the effects of anthropogenic disturbances on Eilat's coral reefs.微量元素（trace elements）对所有生物的生长与发育至关重要。目前学界对红海寻常海绵（demosponges）的元素组成及痕量金属生物学特性仍知之甚少。本研究构建了首个海绵元素组成基础数据库，为后续探索海绵调控金属摄取、富集与储存的机制提供了必要的研究基础。 本研究通过电感耦合等离子体（ICP）检测法，测定了16种常见海绵的金属元素含量。结合多种统计方法，分析了金属元素间的相关性，并筛选出金属元素浓度显著偏高或偏低的海绵物种；同时计算生物富集因子，以对比海绵与当地沉积物的金属含量。 研究结果显示：斯氏薄膜海绵（Theonella swinhoei）的砷与钡含量极高，分别较其他所有物种及当地沉积物高出至少200倍；直立海绵（Hyrtios erecta）的铝、铬、铁、锰、钛及钒浓度显著高于其他所有物种，这一现象源于该海绵的骨骼纤维中富集并包裹了沉积物；棒状软海绵（Suberites clavatus）的镉、钴、镍及锌浓度显著高于其他所有物种及当地沉积物，表明其对这些金属具有主动富集能力，该物种的铁浓度也位列第二，但并未出现直立海绵与当地沉积物中显著偏高的铝、锰及钛浓度，这一差异表明棒状软海绵可主动摄取并富集铁，这一现象在罗氏管海绵（Niphates rowi）中也有发现；杯形厚皮海绵（Crella cyatophora）的硼浓度显著高于其他所有物种。 上述结果表明，痕量元素在特定海绵物种中发挥着特异性作用，值得开展进一步研究；同时本研究结果可为监测人为扰动对埃拉特珊瑚礁的影响提供基准参照。