The Koster Trench is the deepest part of the Kosterfjord (Skagerrak, North Sea), which stretches southward along the west coast of Sweden. Since 2009 Kosterfjord has been included in the Marine Protected Area Kosterhavet National Park. To effectively manage national parks, long-term time series of ecological data are needed and those can be derived from local sediment archives. In this study we present multiproxy geochemical (bulk TOC, C/N and heavy metals) and micropaleontological (dinoflagellate cysts, selected palynomorphs and benthic foraminifera) data from a sediment core taken in the southern part of the Koster Trench. Radiometric dating by ²¹⁰Pb and ¹³⁷Cs shows that the core archived the environmental changes that took place between 1988 and 2012. The TOC, heavy metals and foraminiferal indices indicate mainly high to good Ecological Quality Status, with moderate ecological quality for arsenic concentrations. Dinoflagellate cysts suggest a major change occurring in the upper water column around 2002. The cysts of Pentapharsodinium dalei peak around 1992 and show overall slightly higher relative abundances between 1988 and 2002. Increased abundance of Biecheleria baltica cysts, heterotrophic species, oligotrichids, pollen and spores characterise the upper core part deposited from 2002 to 2012. Also, there is a clear increase of Alexandrium cysts in the top of the core (~2008–2012). Benthic foraminifera show a major faunal change reflected in a significant increase of agglutinated species (mainly Textularia earlandi) from 2007 towards present day, while the lower part of the core (1988–2007) is dominated by calcareous species. Overall, the changes demonstrated by the dataset suggest an increased freshwater input or a higher river/land runoff, as supported by climatic and hydrographical data showing increased precipitation over the study area, decreasing salinity, and an increasing trend in particulate organic carbon in the surface waters. These changes, in combination with trawling activities, which have been moved to the deepest part of the trench since 2009, seem to favour dinoflagellate and benthic foraminiferal species with mixotrophic and omnivorous feeding strategies. Similar to the dinocysts, calculated foram-AMBI and NQI_foram indices show a shift around 2002 suggesting that environmental changes occurring in the study area are likely linked to darkening of coastal waters.

Koster海沟是Kosterfjord（北海Skagerrak）的最深部分，沿瑞典西海岸向南延伸。自2009年以来，科斯特峡湾已被列入海洋保护区科斯特哈维国家公园。为了有效地管理国家公园，需要长期的生态数据序列，这些数据可以从当地的沉积物档案中获取。在这项研究中，我们从位于科斯特海沟南部的沉积物岩心中获得了多代理地球化学数据（大宗TOC，C / N和重金属）和微古生物学（恐龙鞭毛虫囊肿，精选的类孢粉和底栖有孔虫）数据。放射性测年²¹⁰ Pb和¹³⁷Cs显示，核心记录了1988年至2012年之间发生的环境变化。TOC，重金属和有孔虫指数主要表明生态质量状态为高到良好，而砷浓度的生态质量则为中等。甲藻建议在上水柱周围2002年发生的囊肿发生重大变化Pentapharsodinium大雷1992年大约为峰值，并显示1988年和2002年的丰度增加之间的整体略高相对丰度Biecheleria波罗的海囊肿，异养品种，oligotrichids，花粉和孢子表征2002年至2012年沉积的上层核心部分。此外，亚历山大大帝明显增加了核心顶部囊肿（〜2008–2012）。底栖有孔虫显示出主要的动物区系变化，这反映在凝集物种（主要是Textularia earlandi）的显着增加上。）从2007年到现在，而核心的下半部分（1988-2007年）则以钙质物种为主。总体而言，数据集显示的变化表明淡水输入量增加或河流/土地径流增加，这要归功于气候和水文数据，表明研究区域的降水增加，盐度降低以及地表颗粒有机碳的增加趋势水域。这些变化与拖网活动相结合，自2009年以来，拖网活动已移至海沟的最深处，似乎偏爱具有鞭毛和杂食性进食策略的鞭毛和底栖有孔虫物种。类似于dinocysts，计算出的有孔虫，AMBI和NQI_有孔虫 指数显示2002年左右发生变化，表明研究区域发生的环境变化可能与沿海水域变黑有关。