The site of the Boknis Eck Time Series (BE) is located at the entrance of the Eckernförde Bay (54°31.2' N, 10°02.5' E) in the southwestern Baltic Sea. It has a water depth of 28 m with muddy sediments. Riverine inputs into the Eckernförde Bay are negligible and thus the overall hydrographic setting at BE is dominated by the regular inflow of North Sea water through the Kattegat and the Great Belt. Seasonal stratification occurs usually from mid-March until mid-September and causes pronounced hypoxia which sporadically become anoxic.

Lake Temo (IT10-006-A) is located in north-west Sardinia. The construction of the dam began in 1971 and ended in 1984. The reservoir lies at 226 m a.s.l. and has an area of 4.81 km2, a mean depth of 15.8 m and a maximum capacity of 91 x 106 m3. Its catchment extends for 142 km2.

Cabras Lagoon is located on the west coast of Sardinia (Italy), in the Gulf of Oristano (39°56’37’’N, 08°28’43’’E), and occupies about 2280 ha, with a mean water depth and maximum of 1.6 and 3 m respectively. The watershed of the site extends over approximately 430 km2. The input of freshwater into the lagoon is scarce and irregular because of the semi-arid Mediterranean climate. Most of the freshwater comes from the small Mare ‘e Foghe River, located in the north. The predominance of agriculture in the region and the release of poorly depurated urban waste account for the high nutrient loads deposited in Cabras Lagoon. The resident population of about 38,000 inhabitants is grouped in 19 urban centres, the largest being Cabras, which is located on the southeast coastal side of the lagoon. During the twentieth century, the lagoon and its watershed underwent several modifications as a consequence of human activities that affected the hydrology and hydraulics of the region. In addition, in the late 1970s, water exchange with the sea was altered by the dredging of a large canal, the Scolmatore (spillway), which connected the lagoon with the adjacent Gulf of Oristano. The canal was constructed to avoid flooding of adjacent land during the heavy rainfall that occurs in winter. In addition, a cement dam was built into the Scolmatore to prevent further increases in the lagoon’s salinity and artificial barriers were constructed to control the fish catch, thereby impeding direct communication between the lagoon and the sea. Now the only link to the sea is via four very narrow creeks that flow into the large canal from the southern part of the lagoon over the barrier. The lagoon has a high economic rating due to ex¬tensive fishery activities, involving about 300 people and those involved in related enterprises. In the site, in addition to the guard houses and warehouses of fishermen, there is also a restaurant, where the products of fishery in the lagoon are offered. In 1998, fish productivity reached 40,000 kg km-2, corresponding to a catch of 850 tonnes but these values fell to around 20,000 kg km-2 and less than 80 tonnes after 1999. In fact, its high trophic status has often exposed the lagoon to important dystrophic crises, which have caused large reductions in its fishing productivity. Scientific monitoring has been carried out since the strong dystrophic crisis that affected Cabras Lagoon during the summer of 1999, killing the whole aquatic biota. A long-term series of data is available and derives from high-frequency measurements and samplings to assess environmental and biological parameters. In particular the data concern the main trophic descriptors (Secchi depth, temperature, pH, conductivity, dissolved oxygen and saturation, alkalinity, NH4-N, NO2-N, NO3-N, total nitrogen, soluble reactive phosphorus, total phosphorus, dissolved silica) and phytoplankton abundances, as chlorophyll a, cell densities and biomass, class and species composition. The activity was interrupted in 2009.

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.

Runoff and runoff chemistry at LTER Zöbelboden, Austria

The Chalk Karst observatory groups different karst sites on the Cretaceous Chalk located at the Paris Basin (Norville, Radicatel, Yport, Saint-Martin-Le-Nœud). These karst watersheds range from 10 to 200 km2 and the land use consists of agriculture and grazing under oceanic climate. There are characterized by chalk plateaus covered with clay-with-flints owing to chalk weathering constituting a fairly impervious layer and with quaternary silts. These surficial formations range from 3 to 20 meters depth and are highly susceptible to crusting, compaction, and erosion, particularly during autumn and winter. A numerous swallow holes locally penetrates the chalk through the above-mentioned impervious layer, resulting in a strong connection of the surface with the aquifer inducing infiltration of turbidity releases at spring and well used to drinking water (up to 500 NTU). These Chalk karst sites are one the sites of the French SO-KARST labellised by INSU-CNRS and are a part of the French RBV-Network and ZA Seine.

Lake Cuga (IT10-003-A) is located in the north-western part of Sardinia. The reservoir was built in 1965, but its first filling was in 1975. It lies at an altitude of 114 m a.s.l. and is extended for about 58 x 106 m2, with a maximum and average depth of 45 m and 11 m, respectively. It has a volume of 34 x 106 m3. The waters are used mainly for irrigation and drinking supplies. Cuga Lake is classified as eutrophic since the early years of its filling.

Lake Monte Lerno (IT10-004-A) is located in the North East part of Sardinia in the municipality of Pattada. Its construction was completed in 1980. The catchment area is extended for 160 km2. The reservoir lies at 563 m a.s.l. and has a maximum area of 4.4 km2, a mean depth of 14.9 m and a volume of 89.5 x 106 m3 of water. Its waters are used for drinking and irrigation. Lake Monte Lerno is classified as eutrophic.

Lake Cedrino (IT10-002-A) is the result of the dam on the Cedrino River built in 1984. The lake is located in the eastern centre of Sardinia. It has a surface area of 1.5 km2 and a volume of 20 x 106 m3 when it is filled to the maximum share (103 m a. s.l.), and a mean depth of 26.5 m. The catchment covers about 627 km2.

Helgoland Roads summary The Helgoland Roads time-series, located at the island of Helgoland in the German Bight, approximately 60 km off the German mainland (54°11'N 7°54'E), is one of the richest temporal marine datasets available. The time-series was initiated in 1962 at the Helgoland Roads site, which is located between the main island of Helgoland and a small sandy outcrop, the so-called 'dune'. The location near Helgoland is of particular interest because the site is essentially in a transitional zone between coastal and oceanic conditions, which is seen most clearly in the salinity patterns at Helgoland Roads. Initially, the sampling frequency was thrice weekly, but this was increased to daily in the early 1970s. Since then, the high sampling frequency has provided a unique opportunity to study long-term trends in abiotic and biotic parameters, but also ecological phenomena, such as seasonal interactions between different foodweb components, niche properties, and the dynamics and timing of the spring bloom (Grüner et al. 2011; Mieruch et al. 2010; Tian et al. 2008; Wiltshire et al. 2015; Wiltshire et al. 2010). The measured parameters comprise phytoplankton, temperature, salinity, and nutrient analyses. Inorganic nutrients. The taxon list now contains over 350 entities (with 230 distinct species). Both the phytoplankton and chemical dataseries are fully quality-controlled, based on original data sheets and metadata (Wiltshire and Dürselen, 2004; Raabe and Wiltshire, 2009). The phytoplankton time-series is augmented by the biological parameters zooplankton, rocky shore macroalgae, macro-zoobenthos, and bacteria, providing a unique opportunity to investigate longterm changes at an ecosystem scale. Some historic data sets are also available and have been archived in the online repository Pangaea, alongside all core phytoplankton and environmental data sets for Helgoland Roads (Kraberg et al. 2015). Analyses by Wiltshire et al. (2010) have demonstrated the statistical significance of these changes, with temperature since 1962 amounting to 1.7°C (Wiltshire et al., 2010). In tandem with the increases in temperature and salinity, nutrient dynamics at Helgoland Roads have also changed considerably, with phosphate concentrations having declined significantly since 1962. Long-term trends are also seen in the biota, with Diatoms in particular having exhibited an increase in abundance, with a concomitant increase in positive trend for total Dinoflagellates (see also (Wiltshire et al. 2008)). This was not a gradual change, but a rapid shift from negative to positive anomalies around 1998. The exact causes for this are still under investigation. Breaking this down to monthly trends, the swing seems to be largely driven by shifts in autumn and winter. There was also a significant shift in seasonal densities of individual Diatom species (Guinardia delicatula, Paralia sulcata) and in the numbers of large Diatoms (e.g. Cocinodiscus wailesii), which are difficult for copepods to graze. The large Diatom Mediopyxis helysia has recently been observed for the first time and now occurs almost throughout the year, with an intensive bloom in spring 2010 (Kraberg et al. 2012). Generally speaking, the spring Diatom bloom now appears to start later, if the preceding autumn was very warm (Wiltshire and Manly, 2004). It is worth noting that species introductions are also occurring in the zooplankton, with the ctenophore Mnemiopsis leidyi being the most obvious new species (Boersma et al. 2007). References Boersma M, Malzahn AM, Greve W, Javidpour J (2007) The first occurrence of the ctenophore Mnemiopsis leidyi in the North Sea Helgoland Marine Research Grüner N, Gebühr C, Boersma M, Feudel U, Wiltshire KH, Freund JA (2011) Reconstructin g the realized niche of phytopankton species from environmental data: fitness versus abundance approach Limnology and Oceanography methods 9:432-442 Kraberg A, Carstens K, Tilly K, Wiltshire KH (2012) The diatom Mediopyxis helysia at Helgoland Roads: a success story? Helgoland Marine Research 66:463-468 Kraberg AC, Rodriguez N, Salewski CR (2015) Historical phytoplankton data from Helgoland Roads: Can they be linked to modern time series data? Journal of Sea Research 101:51-58 Mieruch S, Freund JA, Feudel U, Boersma M, Janisch S, Wiltshire KH (2010) A new method for describing phytoplankton blooms: Examples from Helgoland Journal of Marine Systems 79:36-43 Tian Y, Kidokoro H, Watanabe T, Iguchi N (2008) The late 1980s regime shift in the ecosystem of Tsushima warm current in the Japan/ East Sea: Evidence from historical data and possible mechanisms Progress in Oceanography 77:127-145 Wiltshire KH, Boersma M, Carstens K, Kraberg AC, Peters S, Scharfe M (2015) Control of phytoplankton in a shelf sea: Determination of the main drivers based on the Helgoland Roads Time Series Journal of Sea Research 105:42-52 Wiltshire KH et al. (2010) Helgoland Roads: 45 years of change in the North Sea Estuaries and Coasts DOI 10.1007/s12237-009-9228-y Wiltshire KH et al. (2008) Resilience of North Sea phytoplankton spring bloom dynamics: An analysis of long-term data at Helgoland Roads Limnology and Oceanography 53:1294-1302