The dataset contains monthly data of transparency measured as Secchi depth at the Ghiffa station (deepest point) during 1988-2018

This is a long-term monitoring study of freshwater zooplankton and phytoplankton population changes after introduction of the mysid, Mysis relicta Lovén, 1862 in lake Jonsvatnet. It is an oligotrophic lake located in central Norway (63° 22’ N, 10° 37* E), 150 m above sea level. The lake has three basins divided by narrow sounds with depths of 1 – 3 m. The major basin is Store Jonsvatnet with surface area of 12,4 km2 and the two smaller ones are Lille Jonsvatnet and Kilvatnet with surface areas of 1,6 km2 and 0,8 km2 respectively. The maximum depths of the three basins are 97 m, 37 m and 34 m respectively and the average depth of the lake is 37 m. Method: Plankton are sampled at one station in each lake basin. All samples are taken during the period June-October, twice a month in June - August, once a month in September and one sampling of mysids in late October. Zooplankton is sampled with a 1 m long tube sampler (volume 5 l). A vertical column of water extending from 0 to 20 m depth is consistently sampled every 1 m. Samples from 5 m layers are mixed together and treated as one sample. Phytoplankton is sampled with a water sampler (volume 1.6 l). A vertical column of water extending from 0 to 10 m depth is consistently sampled every 1 m. Samples from 5 m layers are mixed together and treated as one sample. Mysis relicta is sampled in Lille Jonsvatnet with vertical net hauls (net opening 1 m2, mesh size 500 µm) from 1 m above bottom to to the surface.

Lake Kitaura is typical eutrophic lake in Japan. The maximum and average depth is 10 m and 4.5 m, respectively.

These data are seven freshwater parameters of Srebarna Lake. They are: water depth (m) of the lake, pH, conductivity, transperance Secchi (m), the amount of NO2, the amount of PO4 (mg/l) and the amount of Chlorophil a (mg/l). They were taken in May, August and November 2012 and these are data for spring, summer and winter season.

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.

Santa Giusta occupies an area of 8 km2, with a mean depth of 1 m. Rio Pauli Maiori and Rio Pauli Figu are the two primary freshwater inputs, both located on the lagoon’s east side (Fig. 1b). Santa Giusta also experienced substantial human modification during the 20th century, resulting in profound ecosystem alterations. The Pesaria channel, which originally connected the lagoon to the sea through the Tirso River outlet was deepened, widened, and separated from the river. An industrial harbour was subsequently built, which was connected to the lagoon through an industrial canal controlled by bulkheads. A fish catch system was constructed in the final portion of the Pesaria channel. In 1995, a diversion canal for Oristano urban wastes (the main urban town in the catchment) was built. Despite the canal, the high inorganic nutrient concentrations and algal biomass remained unchanged (Sechi et al. 2001). Macrobenthic algae and phytoplankton are the most important primary producers in Santa Giusta. Sechi et al. (2001) reported several fish kill events associated with harmful algal species blooms in this lagoon. Santa Giusta sediments show high levels of TOC and OM, especially in surface layers (1‒2 cm) in the north and south lagoon areas (Magni et al. 2008). Lugliè et al. (2002) showed Santa Giusta sediment grain sizes exhibited a degree of heterogeneity, but the finer fractions were primarily located in the south-central lagoon area, consistent with central and peripheral canals dredged in the 1970s to facilitate seawater flow into the lagoon. From 1990, the trophic status of the lagoon was always kept under control. It was thus possible to monitor the course of the trophy after the waste was diverted. Even recently (summer 2010) serious events of fish death there were. 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.

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

S’Ena Arrubia Lagoon is located along the central western coast of Sardinia (39.83° N, 8.57° E); it is 1.2 km2 in area and has a mean depth of 40 cm. Freshwater input is supplied from the watershed by two rivers: Rio Sant’Anna (also called Diversivo), which drains an area of 78.4 km2 and showed no runoff from April 2001 to March 2002; and the Canale delle Acque Basse (also called Idrovora), which drains 50 km2 mostly originating from the drying up of a pond over 3000 ha wide and dedicated mainly to farming and cattle-breeding. This channel is below sea level and water is pumped from it into the lagoon. A large part of the catchment area is used for intensive arable farming and cattle breeding, and as a result, the freshwater in the Idrovora canal is very rich in nutrients. The water in the lagoon is exchanged with sea water by means of a sea-mouth canal built in the 1970s (length = 230m, width = 25m, depth = 1.3m). Engineering works were carried out in 2000 to widen the sea mouth of the lagoon in order to improve tidal flushing and thus reduce its high trophic levels and improve its hydrodynamics. The dimensions of the new inlet vary in different places. It is 30 m wide and 0.70 m deep near the lagoon, 60 m wide and 2 m deep in the central part and 32 m wide and 1.30 m deep at the sea mouth. Climate is Mediterranean with long hot summer and short mild rainy winter, generally precipitation and consequent water inflows are low, the year average is 650 mm. S’Ena Arrubia Lagoon is very eutrophic because of the intense arable and stock-rearing activities in its watershed and dystrophic crises and fish kills occur occasionally. Anoxia and dystrophic crises were observed as early as the 1960s. The principal human activities in this wetland are fishing, outdoor recreation, education and scientific research. From 1990, 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 collection of data was interrupted in 2003.

Data refer to on-site measurements and water samples collected in the mesotrophic eastern and eutrophic western basin of Lake Balaton. The data sets covers various physicochemical variables including water temperature, conductivity, pH, total suspended solids, Secchi depth, light extinction coefficient and chlorophyll a concentration for phytoplankton. Samples were collected with a tubular water column sampler.

The Site is located on the northeast Brazilian coast, East Brazil LME, and includes the seascape extending from the coast to the continental slope. The coastal area is formed by an ecosystem complex including remnantes of Atlantic forest, mangroves, seagrass beds and coraline reefs. These ecosystems are interconnected along the seascape over the typically carbonatic shelf, with widths around 18 nautical miles. Along the shelf, submerged channels related to continental drainage in glacial periods, and submerged reefs, form habitats responsible for supporting resources exploited by intense fishing activity. The outermost portion of the continental shelf, considered as an area of significant biological and ecological interest (EBSA), is a biodiversity hotspot, home to reef fish spawning aggregations, and higher fish yield associated with evidence of sub-surface upwellings. These seascape support complex ecological processes, subject to intense use, in an area recognized as a priority for conservation. The presence of Marine Protected Areas reflects this characteristic, both for the need to protect these environments, and for the socio-economic importance, with two protected areas for sustainable use (APAs) and one for Integrated Protection (Park), organized in mosaic.