Silent survivors: diatom resilience in Mediterranean Temporary Ponds

Mediterranean Temporary Ponds (MTPs) are ephemeral freshwater habitats hosting a large number of aquatic and terrestrial organisms. Among these, diatoms represent the bioindicators that contribute mostly to Earth's global primary production. Herein, we focused our attention on the role of seasonality and hydroperiod on benthic diatoms of MTPs. We analyzed the diatom community turnover along one year in two MTPs in the Latium region, Italy. The two MTPs showed different levels of anthropogenic pressures. Our results demonstrated that hydroperiod length and seasonality showed a moderate influence on diatom richness of MTPs; in particular, although the highest number of species was found during spring, taxonomic diversity remained stable at seasonal and inter-annual level despite strong changes in community composition and hydroperiod length. Overall, sampling sites showed different ecological conditions and chemical drivers: protected site was dominated by species occurring in minimally impacted oligo- to mesotrophic waters; unprotected site with high EC and ORP was dominated by species occurring in euryhaline brackish waters. Moreover, physicochemical parameters showed a low influence on diatom assemblages in the protected site and a strong influence in the unprotected site. No significant correlation between diatom ecological guilds and physicochemical parameters emerged. While for all the seasons the dominant guild was the motile guild, no inter-season variations emerged: diatom communities and ecological guilds in MTPs are resilient to seasonal variations. To provide novel insights, future research should focus on additional environmental drivers such as nutrient availability, sediment composition, and hydrological variability, including long-term monitoring plans.

Full article: https://doi.org/10.1016/j.csr.2025.105547

地中海临时池塘（Mediterranean Temporary Ponds, MTPs）是一类短期存在的淡水生境，孕育了丰富的水生与陆生生物类群。其中，硅藻（diatoms）是兼具生物指示功能且对地球全球初级生产力贡献最为突出的类群。本研究聚焦于季节动态与水文周期（hydroperiod）对地中海临时池塘底栖硅藻的影响，对意大利拉齐奥大区的两处地中海临时池塘开展了为期一年的硅藻群落更替动态监测。这两处采样点受人为干扰的程度存在显著差异。

研究结果显示，水文周期长度与季节动态对地中海临时池塘的硅藻物种丰富度存在中等程度的影响；具体而言，尽管春季的硅藻物种数量最多，但即便群落组成与水文周期长度发生剧烈变化，其分类多样性在季节与年际尺度上仍保持稳定。

总体而言，两处采样点的生态环境与化学驱动因子存在显著差异：受保护样点的硅藻群落以栖息于低干扰寡-中营养化水体的物种为主；未受保护样点的电导率（Electrical Conductivity, EC）与氧化还原电位（Oxidation-Reduction Potential, ORP）较高，其硅藻群落则以广盐性咸淡水生境的物种为优势类群。此外，理化参数对受保护样点的硅藻群落组成影响较弱，而对未受保护样点的影响则较为显著；未发现硅藻生态类群与理化参数间存在显著相关性。

尽管所有季节的优势生态类群均为运动型类群（motile guild），但未观测到显著的季节间差异——地中海临时池塘的硅藻群落与生态类群对季节动态具备良好的抗干扰韧性。

为进一步揭示该生境的生态学机制，未来研究应聚焦于更多环境驱动因子，如营养盐有效性、沉积物组成与水文变异性，并可考虑建立长期监测方案。

全文链接：https://doi.org/10.1016/j.csr.2025.105547