Production of phosphatase and extracellular stalks as adaptations to phosphorus limitation in Didymosphenia geminata (Bacillariophyceae)

详细信息    查看全文

• 作者：Jon Bray ; Jon O’Brien ; Jon S. Harding
• 关键词：Phosphatase ; Nutrient cycling ; Didymosphenia geminata ; Periphyton ; Phosphorus
• 刊名：Hydrobiologia
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：784
• 期：1
• 页码：51-63
• 全文大小：1,261 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Hydrobiology
  Ecology
  
• 出版者：Springer Netherlands
• ISSN：1573-5117
• 卷排序：784

文摘

Didymosphenia geminata is a benthic bloom-forming diatom that is invasive in many temperate, oligotrophic freshwater ecosystems. D. geminata blooms are unusual, resulting from prolific basal stalk production stimulated by phosphorus limitation. The adaptive value of stalk production and bloom development is disputed. We examined blooms in relation to stalk biomass, biovolume and phosphatase activity. An austral summer survey of 15 sites within the Waitaki River of New Zealand compared reference communities (no detectable D. geminata), with those impacted by high and low D. geminata biomass. Sites were compared for differences in phosphatase location and activity using chromogenic substrates, community composition using morphological identifications, and overlying water and pore-water chemistry. Experimental microcosms subjected live proliferations to varied phosphate concentrations, and phosphatase rates and location were examined. Survey results identified phosphatase activity increased with D. geminata biomass, with lowest rates in reference communities. Pools of labile nutrients were detected in D. geminata mats, and in vitro hydrolysis rates were rapid in replete phosphoester conditions (~0.2 mmol l−1 h−1 cm−2 at 16°C), with activity concentrated on stalks. Our results suggest D. geminata bloom development is an adaptation to maximise supply of phosphate under chronic phosphorus limitation.