The shallow coastal water zone of the tide-less southern Baltic Sea is dominated by exposed sandy sediments which are typically inhabited by microphytobenthic communities, but their primary production is poorly studied, and hence four stations between 3.0 and 6.2 m depth were investigated. Sediment cores were carefully taken to keep the natural layering and exposed in a controlled self-constructed incubator. Respiratory oxygen consumption and photosynthetic oxygen production were recorded applying planar oxygen optode sensors. We hypothesized that with increasing water depths the effects of wind- and wave-induced erosion and mixing of the upper sediment layer are dampened and expected higher microphytobenthic biomass and primary production in the incubated cores.

Our data partly confirm this hypothesis, as cores sampled at the most exposed stations contained only 50% chlorophyll a m⁻² compared to the deeper stations. However, primary production was highly variable, probably due to fluctuating sediment-disturbing conditions before the cores were taken. Due to these physical forces sand grains were highly mobile and rounded, and small epipsamic benthic diatoms dominated, which preferentially occurred in some cracks and crevices as visualized by scanning electron microscopy. The data fill an important gap in reliable production data for sandy sediments of the southern Baltic Sea, and point to the ecological importance and relevant contribution of microphytobenthic communities to the total primary production of this marine ecosystem. Oxygen planar optode sensor spots proved to be a reliable, sensitive and fast detection system for ex situ oxygen exchange measurements in the overlying water of intact sediment cores.

无潮的南部波罗的海的浅水沿海地区主要是裸露的沙质沉积物，这些沉积物通常是微植物底栖动物群落居住的地方，但对它们的主要产气研究却很少，因此对3.0至6.2 m深度的四个台站进行了研究。小心地取下沉积物芯以保持自然分层，然后将其暴露在受控的自建培养箱中。使用平面氧气光电传感器记录了呼吸氧气的消耗和光合氧气的产生。我们假设随着水深的增加，风和波浪引起的侵蚀和上部沉积物层混合的影响被减弱，并有望在孵化的岩心中产生更高的微底栖生物量和初级产量。

我们的数据部分证实了这一假设，因为在最裸露的站点采样的岩心仅含有50％的叶绿素a m ^-2相比更深的车站。但是，初级产量变化很大，可能是由于取芯之前沉积物扰动条件的变化所致。由于这些物理力，沙粒具有很高的流动性和圆形度，而小外延底栖硅藻占主导地位，如通过扫描电子显微镜观察到的，这些硅藻优先出现在某些裂缝和缝隙中。该数据填补了波罗的海南部沙质沉积物可靠生产数据中的一个重要空白，并指出了微生底栖生物群落对该海洋生态系统的总初级生产的生态重要性和相关贡献。氧气平面光电传感器斑点被证明是用于完整沉积物岩心上覆水中异位氧气交换测量的可靠，灵敏和快速的检测系统。