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In this study, we successfully implemented a total alkalinity (TA) analyzer in a flow‐through setup, in combination with a FerryBox. The high‐frequency (10 min) measurements along our ship's route revealed that in coastal systems, where carbon fluxes are dynamic, TA can differ significantly (by up to 100 μmol kg−1) between the nearshore and adjacent coastal regions. Even though this study could not account for the net yearly TA production in the coastal region, it demonstrated that there was a seasonal increase in TA of 100–150 μmol kg−1 in coastal waters of the North Sea, equivalent to TA production of 11.7–26.8 mmol m−2 d−1 during the spring and summer months. This seasonal change could not be accounted for by riverine contributions, but instead was probably related to seasonal organic matter production and processing in coastal and nearshore regions. Bottom sediments and the tidally coupled biogeochemical reactor between coastal (North Sea) and nearshore (Wadden Sea) regions are mediating this TA change, and the ~ 4 months lag between the seasonal increase in alkalinity and the peak organic matter production could be explained by the supply of (labile) organic matter and its temperature‐dependent remineralization via both aerobic and anaerobic pathways. [ABSTRACT FROM AUTHOR]

From 2002 to 2005 a FerryBox system was installed aboard two different ferries travelling between Cuxhaven (GE) and Harwich (UK) on a daily basis. The FerryBox system is an automated flow-through monitoring system for measuring oceanographic and biogeochemical parameters installed on ships of opportunity. The variables were recorded in a time interval of 10-20 seconds corresponding to a spatial resolution of about 100m. The dataset provides the parameters water temperature, salinity, dissolved oxygen and chlorophyll-a fluorescence. There is a longer data gap between November 2002 and August 2003 in the time series due to a change of the vessel in October 2002. [ABSTRACT FROM AUTHOR]

The current state-of-the-art of FerryBox systems are presented, and their usage as part of European observing systems such as Alg@line in the Baltic Sea or the coastal observatory COSYNA in the North Sea is discussed as well as data management systems. An overview of diverse FerryBox measurement activities is provided, covering the wide and varied potential for utilizing FerryBox data. One innovative technical component is the application of newly developed sensors suitable for FerryBox systems that focus on biogeochemical processes. This component could fill currently existing gaps of robust biogeochemical observations in the oceans and may create, together with the high spatial and temporal resolution of FerryBox systems, the possibility for new insights into physical and biogeochemical processes that were impossible to study before. Such new insights could contribute to the European Marine Strategy Framework Directive (MSFD) and include observations of the coastal carbonate system and its interaction with climate change or eutrophication and productivity. [ABSTRACT FROM AUTHOR]

Results from two field campaigns in the Chilean fjords region are presented to demonstrate the benefits and limitations of the 'pocket FerryBox' for monitoring from ships of opportunity. The October 2009 (spring) campaign covered the region of the Chilean coast between 41.5° and 46.7°S, and that in March 2010 (autumn) covered the region between 41.5° and 51.8°S. In the campaigns the pocket FerryBox-a portable flow-through system for underway multiparametric monitoring-was installed temporarily on board the vessel M/V Ro-Ro Evangelistas. The taking of water samples allowed posterior calibration of the sensors and analyses for nutrients and plankton. The pocket FerryBox may be configured with multiple sensors [in this case temperature, salinity, dissolved oxygen, chlorophyll-a fluorescence, pH, turbidity, and colored dissolved organic matter (CDOM)] and includes the hardware and software for data acquisition and real-time presentation. In the Chilean campaigns multiple transects of up to 1700 km in length were obtained, which provided a unique and highly valuable dataset at a very low cost. The data uncovered a number of previously unreported results, including a tidally driven low dissolved oxygen zone in the Corcovado Gulf, a high level of spatial and temporal variability of, and a complex relationship between, dissolved oxygen and chlorophyll-a fluorescence, and the detection of high concentrations of CDOM in the vicinity of the Laguna San Rafael. The campaigns confirm that the pocket FerryBox may be easily installed on board ships of opportunity to obtain rapid, low-cost, and spatially extensive surveys of highly relevant surface water properties. [ABSTRACT FROM AUTHOR]

In 2002, the Helmholtz-Zentrum Geesthacht, Germany, started to use FerryBox-automated monitoring systems on Ships of Opportunity to continuously record standard oceanographic, biological and chemical in situ data in the North Sea. The present study summarises the operational experience gathered since the beginning of this deployment and reflects on the potential and limits of FerryBox systems as a monitoring tool. One part relates to the instrumental performance, constancy of shipping services, and the availability and quality of the recorded in situ data. The other considers integration of the FerryBox observations in scientific applications and routine monitoring campaigns. Examples are presented that highlight the added value of the recorded data for the study of both long- and short-term variability in water mass stability, plankton communities and surface water productivity in the North Sea. Through the assessment of technical and scientific performance, it is evident that FerryBoxes have become a valuable tool in marine research that helps to fill gaps in coastal and open ocean operational observation networks. [ABSTRACT FROM AUTHOR]

Investigation of phytoplankton biodiversity, ecology, and biogeography is crucial for understanding marine ecosystems. Research is often carried out on the basis of microscopic observations, but due to the limitations of this approach regarding detection and identification of picophytoplankton (0.2–2 μm) and nanophytoplankton (2–20 μm), these investigations are mainly focused on the microphytoplankton (20–200 μm). In the last decades, various methods based on optical and molecular biological approaches have evolved which enable a more rapid and convenient analysis of phytoplankton samples and a more detailed assessment of small phytoplankton. In this study, a selection of these methods (in situ fluorescence, flow cytometry, genetic fingerprinting, and DNA microarray) was placed in complement to light microscopy and HPLC-based pigment analysis to investigate both biomass distribution and community structure of phytoplankton. As far as possible, the size classes were analyzed separately. Investigations were carried out on six cruises in the German Bight in 2010 and 2011 to analyze both spatial and seasonal variability. Microphytoplankton was identified as the major contributor to biomass in all seasons, followed by the nanophytoplankton. Generally, biomass distribution was patchy, but the overall contribution of small phytoplankton was higher in offshore areas and also in areas exhibiting higher turbidity. Regarding temporal development of the community, differences between the small phytoplankton community and the microphytoplankton were found. The latter exhibited a seasonal pattern regarding number of taxa present, alpha- and beta-diversity, and community structure, while for the nano- and especially the picophytoplankton, a general shift in the community between both years was observable without seasonality. Although the reason for this shift remains unclear, the results imply a different response of large and small phytoplankton to environmental influences. [ABSTRACT FROM AUTHOR]

Abstract: The concentrations of chlorophyll-a ([chl-a]) and total suspended matter ([TSM]) are important parameters in biological oceanography. [Chl-a] is a commonly used proxy for estimating phytoplankton biomass while [TSM] also includes detrital material and mineral particles and thus influences light attenuation and photosynthetic activity in the water column. For characterizing the distribution (patchiness) of both parameters adequately over a longer time period, fast and effective measurement methods are required that can also be applied in situ or continuously. Thus, alternatively to direct determination of [chl-a] and [TSM], optical proxy values are often measured. The PSICAM is an integrating cavity approach for measuring absorption coefficients of water constituents with high precision which can be used also continuously (flow-through-PSICAM). In this study, the performance of these absorption measurements for [chl-a] and [TSM] determination was evaluated and compared with the performance of traditional approaches using chl-a fluorescence and turbidity measurements. Data were collected in the German Bight (North Sea) in 2010 and 2011. For [chl-a], fluorescence measurements are compared with pigment absorption coefficient values at a wavelength of 676nm (a Φ 676nm), while the [TSM]-proxies were turbidity and particle absorption at 700nm (a p 700nm). As reference data, HPLC-determined [chl-a] and gravimetrically determined [TSM] were used. Our results showed linear relationships between [chl-a] and fluorescence or a Φ 676nm, respectively. Coefficients of determination (R2) were in a range of 0.71 to 0.88, with the higher values related to the absorption measurements. Furthermore, it was demonstrated that fluorescence underestimates [chl-a] depending on ambient photosynthetically active radiation (PAR). Linear relationships were also observed between [TSM] and its optical proxies with R2 values between 0.93 and 0.98. Turbidity measurements appeared to be influenced to a certain extent by the physical properties of the suspended material, resulting in a slightly higher variability than the a p 700nm measurements. Absorption measurements turned out to be promising optical proxies for determining [TSM] and [chl-a] due to their lower variability compared with the other proxies. This improved accuracy could be already partially achieved also for continuous measurements. Moreover, a combination of the different optical methods has the potential to provide additional information besides concentration, such as the source of TSM in the water or physiological condition of the phytoplankton. [Copyright &y& Elsevier]

In May 2016, the remote-controlled Automated Filtration System for Marine Microbes (AUTOFIM) was implemented in parallel to the Long Term Ecological Research (LTER) observatory Helgoland Roads in the German Bight. We collected samples for characterization of dynamics within the eukaryotic microbial communities at the end of a phytoplankton bloom via 18S meta-barcoding. Understanding consequences of environmental change for key marine ecosystem processes, such as phytoplankton bloom dynamics requires information on biodiversity and species occurrences with adequate temporal and taxonomic resolution via time series observations. Sampling automation and molecular high throughput methods can serve these needs by improving the resolution of current conventional marine time series observations. A technical evaluation based on an investigation of eukaryotic microbes using the partial 18S rRNA gene suggests that automated filtration with the AUTOFIM device and preservation of the plankton samples leads to highly similar 18S community profiles, compared to manual filtration and snap freezing. The molecular data were correlated with conventional microscopic counts. Overall, we observed substantial change in the eukaryotic microbial community structure during the observation period. A simultaneous decline of diatom and ciliate sequences succeeded a peak of Miracula helgolandica, suggesting a potential impact of these oomycete parasites on diatom bloom dynamics and phenology in the North Sea. As oomycetes are not routinely counted at Helgoland Roads LTER, our findings illustrate the benefits of combining automated filtration with metabarcodingto augment classical time series observations, particularly for taxa currently neglected due to methodological constraints. [ABSTRACT FROM AUTHOR]

Chemical pollution is of concern for the marine environment. New European regulation demands exposure and impact assessment to be conducted in coastal environments in order to define and ensure fulfillment of environmental quality standards. A cost-effective approach for monitoring the over 100,000 km of European coasts is necessary. This proof-of-concept study focuses on the use of unmanned water sampling from a commercial ship of opportunity to implement monitoring of marine contaminants of emerging concern. Marine areas that are not directly affected by river plumes or other direct sources were covered in order to provide information on background pollution. 14 currently used pesticides, 11 pharmaceuticals and personal care products and 3 food additives were detected in water samples through targeted analysis at sub-ng to tenths of ng/L levels in both coastal and offshore areas of the North Sea. Among contaminants, 6 pesticides (dimethoate, fenpropimorph, pendimethalin, propiconazole, tebuconazole and temephos), 3 pharmaceuticals (acetaminophen, naproxen and ketoprofen) and 2 food additives (acesulfame and saccharine) have never been detected before in offshore areas. 4 pesticides (diuron, isoproturon, metazachlor and terbuthylazine), 4 pharmaceuticals (carbamazepine, atenolol, ibuprofen and ketoprofen) and 2 food additives (sucralose and acesulfame) were detected in over 90% of the samples. The antibiotic sulfamethoxazole was detected in 50% of the samples at tenths of pg/L levels, including some offshore areas. Our study highlights that the use of ships of opportunity can provide a key support for the development and cost-effective implementation of marine monitoring of chemical pollutants in Europe and elsewhere. [ABSTRACT FROM AUTHOR]

Determination of spectral absorption coefficients in seawater is of interest for biologic oceanographers for various reasons, but faces also several problems, especially if continuous measurements are required. We introduce the flow-through point-source integrating cavity absorption meter (ft-PSICAM) as a new tool for the continuous measurement of spectral absorption coefficients in a range of 400-710 nm. A description of the system is given and its performance in comparison with a conventional PSICAM has been evaluated on two cruises in 2011 in the southern part of the North Sea (German Bight). Furthermore, factors influencing the measurement are discussed. When comparing the data of both systems, a good linear correlation has been found for all wavelengths ( r > 0.91). Deviations between systems were different with respect to the wavelength examined with slopes of linear fits between 1.1 and 1.65 and offsets between −0.1 and 0.01, with the higher values at shorter wavelengths. They were caused mainly due to contamination of the flow-through system during operation by phytoplankton particles. Focus was also laid on the measurement of chlorophyll- a concentrations ([chl- a]) and total suspended matter concentrations ([TSM]) on the basis of absorption coefficient determination. For this, appropriate relationships were established and [chl- a] and [TSM] values were calculated from the relevant ft-PSICAM absorption coefficients. Their progression matches well with the progression of fluorescence and turbidity measurements made in parallel. In conclusion, the ft-PSICAM is successful in measuring spectral absorption coefficients continuously and resolving relative changes in seawater optical properties. [ABSTRACT FROM AUTHOR]

We present a five-year (1997–2001) numerical simulation of daily mean chlorophyll a concentrations at station Geesthacht Weir on the lower Elbe River (Germany) using an extremely simple Lagrangian model driven by (a) water discharge, global radiation, water temperature, and (b) silica observations at station Schmilka in the upper reach of the Elbe River. Notwithstanding the lack of many mechanistic details, the model is able to reproduce observed chlorophyll a variability surprisingly well, including a number of sharp valleys and ascents/descents in the observed time series. The model's success is based on the assumption of three key effects: prevailing light conditions, sporadic limitation of algal growth due to lack of silica and algae loss rates that increase above an empirically specified temperature threshold of 20°C. Trimmed-down model versions are studied to analyse the model''s success in terms of these mechanisms.In each of the five years the model consistently fails, however, to properly simulate characteristic steep increases of chlorophyll a concentrations after pronounced spring minima. Curing this model deficiency by global model re-calibration was found to be impossible. However, suspension of silica consumption by algae for up to 10 days in spring is shown to serve as a successful placeholder for processes that are disregarded in the model but apparently play an important role in the distinctly marked period of model failure. For the remainder of the year the very simple model was found to be adequate. [Copyright &y& Elsevier]