Dredging can cause increased suspended sediment concentrations (SSCs), light attenuation and sedimentation in marine communities. In order to determine the combined effects of dredging-related pressures on adult sponges, three species spanning different nutritional modes and morphologies were exposed to 5 treatment levels representing realistic dredging scenarios. Most sponges survived under low to moderate turbidity scenarios (SSCs of ≤ 33 mg L−1, and a daily light integral of ≥0.5 mol photons m−2 d−1) for up to 28 d. However, under the highest turbidity scenario (76 mg L−1, 0.1 mol photons m−2 d−1) there was 20% and 90% mortality of the phototrophic sponges Cliona orientalis and Carteriospongia foliascens respectively, and tissue regression in the heterotrophic Ianthella basta. All three sponge species exhibited mechanisms to effectively tolerate dredging-related pressures in the short term (e.g. oscula closure, mucus production and tissue regression), although reduced lipids and deterioration of sponge health suggest that longer term exposure to similar conditions is likely to result in higher mortality. These results suggest that the combination of high SSCs and low light availability can accelerate mortality, increasing the probability of biological effects, although there is considerable interspecies variability in how adult sponges respond to dredging pressures.
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机译：疏can会导致海洋社区的悬浮沉积物浓度（SSCs）升高，光衰减和沉积增加。为了确定疏ed相关压力对成年海绵的综合影响，将三种具有不同营养模式和形态的物种暴露于代表实际疏treatment场景的5种处理水平。大多数海绵在低至中等浊度情况下（SSC≤33μmgL -1 ，日光积分≥0.5μmol光子m −2 d -1 ）长达28 d。但是，在最高浊度的情况下（76 mg L −1 ，0.1μmol光子m −2 d -1 ）有20％，光养海绵海绵分别具有90％的死亡率，而异养的Ianthella basta的组织消退。尽管降低的脂质和海绵健康的恶化表明，长期暴露于相似的条件下，这三种海绵物种均显示出在短期内有效耐受与挖泥相关的压力的机制（例如，眼睑闭合，粘液产生和组织退化）。死亡率更高。这些结果表明，尽管成年海绵对疏dr压力的反应存在很大的种间差异，但高SSC和低光利用率的组合可以加快死亡率，增加生物效应的可能性。
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