Our primary study sites include a set of seven northern Wisconsin and four southern Wisconsin lakes and their surrounding landscapes. The project, which started in 1981, is administered by the Center for Limnology at the University of Wisconsin-Madison.

To support the marine biodiversity and ecosystem dynamics research community in Belgium, the Flanders Marine Institute (VLIZ) has set up a local marine biodiversity observatory.

Piburger See is a small mountain lake in the Eastern Alps (Austria) and was part of the OECD study on eutrophication (OECD, 1980). This lake experienced cultural eutrophication during several decades in the 20th century. In the 1950s and 1960s, recreational activities increased with a concurrent rise in tourism, and increasing amounts of fertilisers were used on nearby fields (Pechlaner, 1968). This resulted in enhanced primary production and rising hypolimnetic oxygen depletion in the lake (Pechlaner, 1979). Lake restoration started in 1970 by exporting anoxic and nutrient-rich hypolimnetic waters with an Olszewski tube (Pechlaner, 1971, 1979). External nutrient loading was reduced by altering fertiliser application and by diverting sewage from a public bath (Psenner, Pechlaner & Rott, 1984). After the installation of the Olszewski tube in June 1970, phytoplankton biomass increased, accompanied by an increase in chlorophyll "a" and total phosphorus (TP) (Rott, 1983; Tolotti & Thies, 2002). The period from 1970 until 1988 was characterised by a marked increase in the filamentous cyanobacterium Oscillatoria limosa C.A. Agardh, which became the dominant algal taxon in the lake and contributed up to 40% to the mean annual phytoplankton biovolume (Rott, 1976; Wolf, 1991). The response of phytoplankton biovolume to lake restoration was delayed by two decades and re-oligotrophication of Piburger See began during the late-1980s (Pechlaner, 1979; Rott, 1983; Pipp & Rott, 1995). At present, Piburger See is oligomesotrophic (Tolotti & Thies, 2002). Since the early 2000s, chlorophyll "a" and phytoplankton biovolume values suggest a reversing trend in lake trophic status with a rising contribution of diatoms including blooms of Asterionella formosa (Tolotti et al., 2005; Tolotti net al. 2012, Thies et al. 2012). Monitoring of lake water quality, control of deep water siphoning discharge and operation of gauges are current activities at this site. A rowing boat for lake water sampling is available. A smaller part of the lake has the status of a research area. During summer, tourism is an important factor at this site (public bath, rowing boats, angling, swimming, walking).

The Abrolhos Bank is located along the eastern Brazilian coast and is characterized by an enlargement of the Brazilian shelf (~46.000 km2), reaching approximately 200 km in width. The Abrolhos Bank encompasses three main megahabitats and a complex bathymetry. Rhodolith beds comprise the largest megahabitat, with 20,904 km² (43% of the mapped area), followed by unconsolidated sediments' megahabitat covering 19,151 km2 (39%) and by the reefal megahabitat with 8844 km2 (18%). Rhodolith beds and unconsolidated sediments are topographically less complex and form larger continuous extensions when compared to the reefal megahabitat, which is structurally complex and more patchily configured, even when examined at the regional scale.

The Laboratory of Marine Ecology is one of the field stations of IBER-BAS, based in the town of Sozopol on the coast of the Black Sea. It is provided with upgraded equipment and modern laboratory facilities necessary for carrying out investigations on the biodiversity and functioning of the coastal marine ecosystems. The laboratory is equipped with facilities for general ecological studies, a chemical and instrumental laboratory, microscopes and stereomicroscopes and a workshop. Main scientific equipment: spectrophotometer and instruments for sediment and water sampling and analysis, a combined pH/dissolved oxygen/conductivity measuring Instrument (WTW), microscopes and equipment for phytoplankton and microbiological research. The laboratory uses SCUBA diving equipment and possesses a small research vessel suitable for work in the coastal zone.

Askö Laboratory is a modern field station that offers excellent research facilities and accommodation in the heart of an extensively studied coastal and open sea area with some unbroken data series dating back 4 decades. It is administered by the Stockholm University, Baltic Sea Centre since 2013, former Stockholm University Marine Research Centre (SMF), an organisation devoted to providing research infrastructure to SU and other interested scientists. Long term monitoring of the benthic, phytobenthic and pelagic ecosystems funded mainly by the Swedish Agency for Marine and Water Management and to a minor part by the Swedish Environment Protection Board and other organisations are located to the area. One main objective is to integrate research and monitoring to increase in-house, national and international collaboration to optimize available resources and scientific progress. Other objectives: To detect changes in the pelagic, phytobenthic and benthic ecosystems related to eutrophication and climate change, to improve management practices of coastal and open sea areas.

Lake Päijänne LTER site constitutes one of the biggest lakes in Finland (and smaller lakes in catchment area) with almost 300 000 habitants in surrounding areas. The lake has been heavily polluted but its condition has been improved, and today the lake has both high economic and social importance for a significant proportion of the Finnish population. There is a long experience of lake research in the L. Päijänne area, including some long-term data series. Research at L. Päijänne is diverse and is already well-equipped with instrumentation supporting long-term monitoring. The research covers large scales from hydrology to fish stock assessment. This research area includes also another large Finnish lake, Lake Konnevesi, as a natural reference lake in the northern branch of the Lake Päijänne system.

We have been monitoring Lake Kasumigaura, the second largest lake in Japan, monthly for nearly four decades. We have monitored not only environmental variables, water quality, nutrients, and heavy metals, but also plankton (e.g., bacteria, heterotrophic nanoflagellates, ciliates, picoplankton, phytoplankton, zooplankton, mysids), primary production, benthos (chironomids and oligochetes), and fish. To increase data availability and the numbers of data users, we created an English web database (http://db.cger.nies.go.jp/gem/moni-e/inter/GEMS/database/kasumi/index.html) in this research period, and strengthened our relationships with international observational networks. We also provided monitoring data to the Japan Long-Term Ecological Research Network (JaLTER; http://www.jalter.org/index.php?ml_lang=en) and published two data papers in the international journal Ecological Research (Takamura et al. 2012 a, b). We have also started to register fish monitoring data in the Global Biodiversity Information Facility (GBIF) (http://www.gbif.org/dataset/f648085b-8e1c-4a79-bc8d-f45d36296564) .

Lake Müggelsee is a shallow (mean depth 4.9 m, max depth 8 m), eutrophic lake situated southeast of the city of Berlin (Germany, 52° 26’ N, 13° 39’ E). The lake is polymictic and usually fully mixed due to the wind fetch of its relatively large surface area of ~750 ha. The River Spree enters the lake from south-east and the outflow is situated in the north-west of the lake. The lake has an average retention time of about 6-8 weeks. Due to its location in a transition zone from a maritime to a more continentally characterized climate, the lake experiences large annual and inter-annual variability in local weather conditions. Data availability spans the time period from 1979-ongoing. Sampling intervals are weekly and biweekly during the winter months. We monitor phytoplankton, zooplankton, and major nutrients and abiotic variables at at weekly temporal scales at 5 different locations across the lake. Fish, macrophytes, MZB, periphyton are sampled yearly. Additionally, we run an automatic lake station (https://www.igb-berlin.de/messstation-mueggelsee) continuously recording water temperature, pH, oxygen, conductivity, fluorescence in -situ in real time. Moreover, the station is equipped with a meteorological station monitoring air temperature, wind, humidity, precipitation, global radiation. Müggelsee is a GLEON (Global Lakes Observatory Network http://www.gleon.org/ ) and an LTER -D site.

Lake Shinji and Lake nakaumi are coupled coastal lagoon lake systems in Japan, and these lakes have suffered detrimental efects by human activities, especially during the last 40 years, because of the big national projects aiming at desalination and reclamation of these lakes. In the year 2000, however, the land reclamation project in Lake Nakaumi was officially discontinued, leaving Honjou area unreclaimed. Shortly thereafter, desalination project was also terminated. This was the end of a large and expensive series of public works projects, and in 2005, these two lakes were included in the list of wetlands of international importance, and the efforts to restore the lakes are undergone.