绿潮藻类暴发对天鹅湖水体和沉积物磷含量的影响

在荣成天鹅湖藻类暴发区域采集新鲜沉积物和丝状硬毛藻（Chaetomorpha spp.），进行室内模拟试验，监测了生长过程中硬毛藻的生物量、磷富集量以及不同处理水体总磷（TP）和可溶性磷（SRP）质量浓度的变化，并分析了藻类生长对沉积物中各形态磷含量的影响。结果表明，当水体磷含量较高时，硬毛藻生长较快，相对生长速率高达14.88%，之后随着水体磷浓度的下降，生长速率逐渐减小。不同处理间硬毛藻的生物量相差很大，高磷含量处理显著高于低磷处理，最大差值可达26.50 g。随着藻类的生长，水体TP和SRP含量明显降低，其中高磷含量处理的TP质量浓度由0.93 mg·L-1降至0.01 mg·L-1，低磷含量处理水体SRP质量浓度均降至0.006 mg·L-1以下。当水体磷含量降至一定水平，沉积物中磷可向水体释放，其中可还原态磷和铁铝结合态磷的降幅分别为23.98%和12.61%。在高磷含量处理组，藻体中磷的富集量显著升高，且当水体磷含量相同的条件下，有沉积物处理的富集量显著高于无沉积物处理。相关分析表明，藻体生物量与水体TP和SRP的相关性较好，其中高磷含量处理组生物量与水体TP、SRP呈高度负相关，而相对生长速率与之呈显著正相关。结果说明，水体及沉积物中磷均可作为硬毛藻生长的营养来源；另一方面，藻类生长可明显降低水体磷含量，并促进沉积物中磷的释放。

Effects of macroalgal blooms on phosphorus concentrations in water and sediments of Rongcheng Swan Lake

The fresh sediments and filamentous algae sampled from the dominated zone of Chaetomorpha spp. in Rongcheng Swan Lake were incubated in laboratory to study the changes of biomass and phosphorus （P） enrichment amount in algae, and total P （TP） and soluble reactive P （SRP） concentrations in water of different treatments. In addition, the influence of algal growth on P forms in sediments was analyzed. The results showed that Chaetomorpha grew faster at high P concentration in water, and relative growth rates （RGR） reached up to 14.88%. However, RGR decreased gradually as the P concentration in water declined. Chaetomorpha biomass varied considerably among different treatments. The biomass at the high P treatments were higher than those at low P treatments, and the great difference reached up to 26.50 g. During the growth period, TP and SRP concentrations in water declined remarkably, and TP concentrations at high P treatments declined from 0.93 mg·L-1 to 0.01 mg·L-1. At the low P treatments, SRP concentrations in water were lower than 0.006 mg·L-1. The sediments can release P for Chaetomorpha growth when water P level was low, and concentrations of redox-sensitive P （BD-P） and Fe/Al-bound P （Fe/Al-P） decreased by 23.98% and 12.61%, respectively. At the high P treatments, P enrichment amount in algae were relatively high. While at the same P level, P enrichment amount at the treatments with sediments was significantly higher than that without sediments. Correlation analysis suggested that algal biomass was well correlated with TP and SRP in water. At the high P treatments, TP and SRP concentrations had significantly negative correlation with algal biomass, but had significantly positive correlation with RGR. The results demonstrate that P nutrient in water and sediments can both promote the growth of Chaetomorpha. Furthermore, algal growth can reduce P concentration in water as well as accelerate P release from the sediments.