摘要
本文海冰的生化数据采集于波罗的海的波的尼亚湾(Hailuoto,芬兰)、波的尼亚海(Norrby,瑞典)和芬兰湾(Tvrminne,芬兰)三个海域。主要来源于2003～2006年开展BIREME项目期间的现场测量和实验,并补充了一些公开发表的相关数据。我们的重点是分析波罗的海海冰内生物活动是否有明显的区域性变化。波的尼亚湾海冰区域的叶绿素α浓度和细菌周转率都较低。然而,我们主要是在紧靠陆地的当年海冰内取样,明显缺失了海冰内最活跃的生物学系统,而这个系统一般都存在于残冰中(例如冰脊)。我们有限的数据表明,波罗的海的最北部海域内,在压力脊的冰固结层下方的受压冰块(keel blocks)和受压冰块间隙水内,藻类密度较高。尽管在顶层和冰内偶尔也能发现丰富的生物,但波的尼亚海和芬兰湾靠陆地海冰的最低层似乎是生物活性的中心。在积雪期间,冰中海藻光照受限,而对于冰底层的藻类,磷酸盐通常是限制性养分。细菌的生长明显被藻类有关的可溶性有机物的生产所控制,因为波的尼亚湾中的生长率低,但外来的可溶性有机物浓度高。在藻华发生期间,相比开放水体中的细菌活性,波的尼亚海和芬兰湾的细菌群落都有较高的周转率,和与藻华发生期间开放水体中相当的活动水平这意味着冬季海冰细菌群落有很强的物质处理能力。
This paper compiles biological and chemical sea-ice data from three areas of the Baltic Sea:the Bothnian Bay (Hailuoto,Finland),the Bothnian Sea (Norrby,Sweden),and the Gulf of Finland (Tv(a|¨)rminne,Finland).The data consist mainly of field measurements and experiments conducted during the BIREME project from 2003 to 2006,supplemented with relevant published data.Our main focus was to analyze whether the biological activity in Baltic Sea sea ice shows clear regional variability.Sea-ice in the Bothnian Bay has low chlorophyll a concentrations,and the bacterial turnover rates are low.However,we have sampled mainly land-fast level first-year sea-ice and apparently missed the most active biological system, which may reside in deformed ice (such as ice ridges).Our limited data set shows high concentrations of algae in keel blocks and keel block interstitial water under the consolidated layer of the pressure ridges in the northernmost part of the Baltic Sea.In land-fast level sea-ice in the Bothnian Sea and the Gulf of Finland,the lowermost layer appears to be the center of biological activity,though elevated biomasses can also be found occasionally in the top and interior parts of the ice.Ice algae are light limited during periods of snow cover,and phosphate is generally the limiting nutrient for ice bottom algae.Bacterial growth is evidently controlled by the production of labile dissolved organic matter by algae because low growth rates were recorded in the Bothnian Bay with high concentrations of allochthonous dissolved organic matter.Bacterial communities in the Bothnian Sea and the Gulf of Finland show high turnover rates,and activities comparable with those of open water communities during plankton blooms,which implies that seaice bacterial communities have high capacity to process matter during the winter period.
