Marine Stations Helgoland and Sylt operated by the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research

: The Marine Stations Helgoland and Sylt are permanent coastal stations in the German Bight operated as one joint research infrastructure by the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI). Using both stations, the south-west region of the North Sea and its ecosystem features are tightly monitored via ecological time series, which are recorded and made available to government offices, professional associations, and research institutes world-wide. The stations are a hub for national and transnational access for guest researchers and visiting scientists in the German Bight. For over fifty years, the stations have served as centres of student education by providing facilities for university courses. The stations operate the coastal research vessels Mya II, Uthörn and Aade. The Biologische Anstalt Helgoland (BAH) is home to the AWI Centre for Scientific Diving, which conducts, promotes, and supports diver-related underwater science within the framework of all AWI research themes. The BAH is also home to the school laboratory OPENSEA, which offers high school students a scientific environment to explore marine science. The Wadden Sea Station on the island of Sylt offers 24 seawater mesocosms for ecological studies of future climate scenarios. Public outreach centres are associated with both locations (BLUEHOUSE and Erlebniszentrum Naturgewalten).


Introduction
The Marine Station Helgoland ("Biologische Anstalt Helgoland") and the Wadden Sea Station Sylt ("Wattenmeerstation List, Sylt") together form a large-scale research infrastructure operated by the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI).Since 1892 on Helgoland, one of the oldest marine stations in the world, scientists have been investigating shelf seas and unique coastal environments.In 1892 the "Biologische Anstalt Helgoland (BAH) was founded, and together with the "Meeresstation" on Helgoland, the first facility was opened (Salewski 2017).In 1924, the BAH was extended to include Wadden Sea and oyster research, with the addition of the "Wattenmeerstation" in List.In 1998, the BAH became an integral part of the AWI.  2 Research capacities for work at the marine stations Helgoland and Sylt The portfolio of the stations comprises personal, remote and virtual access to field samples and data, as well as the provision of modern infrastructure for advanced work in the context of coastal research (laboratories, testing devices, standard sampling procedures, seawater supply, temperature constant rooms, research vessels, accommodation etc.).In addition to the basic facilities, visiting scientists have access to nutrient analyses, micro-and molecular biology laboratories through cooperation with onsite scientists and, uniquely, to outdoor mesocosms capable of simulating ocean warming and acidification under various tidal conditions.The research vessels can be requested for short research cruises to take pelagic or benthic samples.User get access to the facilities for service requests in the user portal www.accessinfra.awi.de.
Both Marine Stations contribute to national and international projects and networks as e.

Long-term observatories Helgoland Roads
The Helgoland Roads time-series, located at 54°11'N and 7°54'E, is one of the richest temporal marine datasets available.It is registered in the Dynamic Ecological Information Management System -Site and dataset registry (DEIMS) as an information management system powered by eLTER.The data set comprises a phytoplankton time series (started in 1962 and sampled daily during the work week) and a zooplankton time series (started in 1975 and sampled three times a week), along with time series for inorganic nutrients (nitrite, nitrate, phosphate, silicate, ammonium), salinity and temperature.Also, several shorter time series (e.g.Chlorophyll a and other data from ferrybox systems) and spatiotemporal datasets exist, and Helgoland scientists are jointly setting standards by linking these data through detailed documentation, quality control and data management to facilitate detailed analyses of long-term ecological change and their societal consequences.In addition to these core time series, bacterial counts have also been carried out for over 40 years, although this time series has recently been discontinued (Gerdts et al. 2004, Lucas et al 2015, Lucas et al 2016, Banos et al 2020).An overview of the microbial parameters acquired at the sampling station "Kabeltonne", Helgoland Roads from 1962 until today is given in Gerdts et al 2004.The macroalgal and macrobenthos communities were investigated periodically (Bartsch & Kuhlenkamp 2000, Franke et al. 2004).However, the fact that the 'Helgoländer Felswatt' is the only habitat of this type in Germany, makes this data set all the more valuable.The high sampling frequency of the Helgoland Roads time series has provided a unique opportunity to study long-term trends in abiotic and biotic parameters (Raabe and Wiltshire 2008, van Beusekom et al. 2009, Wiltshire & Manly 2004, Wiltshire et al 2010), but also ecological phenomena, such as seasonal interactions between different food web components (Boersma et al 2015, Freund et al 2012, Kraberg et al 2019), niche properties, and the dynamics and timing of the spring bloom (Brüwer et al 2023, Meunier et al. 2018, Scharfe et al. 2019, Teeling et al 2012, Wiltshire et al. 2008).It has also facilitated close examination of the dynamics of new species appearing in the local ecosystem.

Sylt Roads
The Sylt Roads time series is closely related to the Helgoland Roads time series and comprises an almost identical parameter set.Sylt Roads was initiated in 1974.Its main station located in the Sylt-Rømø bight close to List/Sylt (55°03'N and 8°46'E) is generally sampled twice a week (ID in DEIMS).

Monthly transect cruises
Additionally, monthly transect expeditions from Helgoland to the Elbe (Cuxhaven) and Eider rivers have been carried out continuously since the beginning of the 1980s, monitoring the coastal transition zone (Lucas et al 2016).Increasingly, time-series data are generated with the assistance of autonomous measuring systems, like e.g. a Ferry Box system on the passenger vessel HELGOLAND.
Description of the time series are given in the Dynamic Ecological Information Management System -Site and dataset registry (DEIMS-SDR) and LTER-D.
The ecological time-series research at Helgoland and Sylt Roads produces extremely valuable data used by science, public authorities, educational institutions, and national/international organizations.
The data are archived in the World Data Centre PANGAEA and can be accessed via the marine-dataportal.To make information about and the knowledge resulting from the HR and SR LTER time series findable and accessible for the scientific community and other interested stakeholder groups meaningful and reproducible data products were already compiled for selected parameters of the LTER time series of HR and SR.The resulting data products are presented on two dashboards (Helgoland Roads Dashboard, Sylt Roads Dashboard), where information about the time series, near-realtime data and the data products are consolidated.

Guest research and education
The stations' educational infrastructure -course and seminar rooms -is regularly used for university practical courses and field excursions, scientific workshops and seminars.Technical support and service for visiting scientists and university courses are complemented by access to biological material at both stations.The supply of marine-sourced material is possible both on-site and by shipment.

School laboratory
The school lab OPENSEA offers a scientific environment to explore marine science, thereby promoting young peoples' scientific thinking.In close cooperation with the scientists, OPENSEA offers experiences outside the classroom for high school graduates with special interests in natural science and marine biology.With hands on experiments in the field and in the lab (Hößle et al 2021, Thiel et al 2023), OPENSEA provides add-ons to the syllabus for high school graduates, and encourages the scholars to actively ask scientific questions, conduct practical biological and chemical experiments, collect field data to find conclusive answers, and to foster scientific thinking.Scholars are introduced to ecological processes very close to current research topics and learn more about the urgent need to protect the oceans.

Material Dispatch
Institutes and universities from all over Germany (and increasingly Europe) have a high demand for living and/or fixed biological material for teaching purposes.The Biologische Anstalt Helgoland operates a material dispatch and supply service that enables researchers and course leaders to acquire such material.The BAH Material Dispatch tries to process all inquiries, but strictly adheres to existing species protection regulations.Accordingly, species that are on the red list cannot be supplied.Conserved and living zoological material, botanical material (living macroalgae), seawater, as well as sediment are offered on a material list and shipped to the requesting institution.

Mesocosms
The AWI Sylt Outdoor Mesocosms (AWISOM) consist of 24 identical mesocosms, each with 1800 l sea water volume and a light-permeable cover.Each mesocosm can simulate tides and currents to recreate conditions as natural as possible for the experimental communities contained within (Pansch et al 2016).Furthermore, it is possible to precisely regulate temperature, carbon dioxide concentration and nutrients within each basin.A multiparameter probe continuously monitors and automatically records pH, salinity, oxygen content and temperature.The mesocosms are operated seasonally from April to October to study the influences of simulated environmental changes (IPCC climate scenarios) on species communities of the Wadden Sea.In winter, AWISOM is shut down to protect the electronics and technology from cold-related damage.However, in addition to the 24 outdoor tanks, there are six further tanks in a large greenhouse, where it is possible to conduct experiments in winter e.The area is about 270 x 100 m in size, located between 5 and 10 m water depth, and is officially classified as a maritime exclusive zone for ship traffic.Six tetrapod-fields have been installed in 5 and 10 m water depth to study the effects of artificial breakwaters on the shallow water fish and macro-invertebrate community.Since summer 2012, the MarGate field contains the first German underwater node system developed in the framework of COSYNA.This system provides continuous and manageable power and network access at 10 separate underwater mutable docking ports, each providing 48V/200W and 100 MBit/1 GBit network connection.Each port can be individually addressed and managed by its registered user (sensor owner) from anywhere in the world to remotely control and manage even complex sensor units.As well as basic hydrographical parameters from the area, the AWI operates multiple sensor systems for the main abiotic and biotic variables (temperature, salinity, depth, tide, turbidity, oxygen, chl-a fluorescence, 3D-current) in near real time (about 1 h delay).
Figure 9: Diver with photo equipment (Picture: AWI) 3 Concluding remarks and future development The Marine Stations Helgoland and Sylt have excellent facilities with a long-term institutional and governmental commitment.They promote a wide range of research topics and experimental approaches.On-site, scientists jointly set standards by providing these data for research and science.This entails detailed documentation, quality control, and data management to facilitate analyses of long-term ecological changes and their societal consequences.The Marine Stations Helgoland and Sylt will continue  operating long-time data series and improve the services provided to internal and external users  and extend the support for use and decision-making by science, society, and politics  and improve the provided services to external visitors  supplying educational institutions and universities with material and providing the best possible service and information  providing a hospitable environment for education and ongoing capacity development building, and for more intensified international (transnational) cooperation Besides continuation of their operational function, both marine stations will intensify their international collaborations.Joint strategies and developments provide a strong infrastructure with immense future potential.Facilitating engagement with stakeholders and governing bodies in discussions, as well as providing pivotal data products is a priority.
The marine stations on Helgoland and Sylt house key infrastructure for fulfilling scientific, educational, societal and logistic obligations according to the statutes of the AWI and the Helmholtz Association.The BAH has a long tradition of generating, archiving and analysing marine, ecological time series.The first temperature and salinity time series were started in 1873.The earliest macroalgal data were also collected in the 19th century.In 1962, one of the most important time series globally, the so-called Helgoland Roads time series on plankton was initiated.The time series Helgoland Roads and Sylt Roads are characterized by a unique combination of length, temporal resolution, and level of detail (range of parameters).
g. the German Marine Research Consortium, German Marine Research Alliance, European Marine Research Network, European Network of Marine Stations and the World Association of Marine Stations.

Freezer
Figure 3: A university course takes plankton samples (Photo: AWI)

Figure 5 :
Figure 5: School lab OPENSEA taking samples in the intertidal (Picture: Uwe Nettelmann, AWI) g. to study the effects of warmer winters.The AWI team has used this facility to test, among other things, the impact of various future scenarios released by the IPCC (Intergovernmental Panel on Climate Change) on marine life (Di Pane, 2022; Fuxjager et al. 2019; Moreno et al. 2022).

Figure 6 :Figure 8 :
Figure 6: Conserved specimens in glass jars for university usage (Picture: Uwe Nettelmann) The coastal long-term observatories contribute to the analysis and knowledge transfer of long-term environmental trends and marine processes in cooperation and exchange with local authorities (e.g.Bundesamt für Seeschifffahrt und Hydrographie/BSH, Umweltbundesamt/UBA) and national and international institutions (e.g.Sir Alister Hardy Foundation for Ocean Science/SAHFOS, National Oceanic and Atmospheric Administration/NOAA), boards (e.g.International Council for the Exploration of the Sea/ICES Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization/IOC-UNESCO), and networks (e.g.Long-term ecological Research Germany LTER-D, European Marine Observation and Data Network/EMODnet, World Register of Marine Species/WORMS).