Nutrient flux and budget in the Ebro estuary

The Ebro river flows to the Mediterranean coast of Spain. During its final stretch, the Ebro behaves in a similar way to a highly stratified estuary. This paper describes the transport of nutrients to the Ebro estuary, evaluates the general movement of nutrients in the estuarine region, using a mass balance approach, and estimates the amounts of nutrients discharged to the coastal environment. Given the strong saline stratification, this study only includes the surface layer that contains the continental freshwater. The annual nutrient budget for the Ebro estuary shows a net excess for nitrogen and phosphorus, while silicate almost attains equilibrium between addition and removal. There are several reasons for gains in nitrogen and phosphorous: a contribution of dissolved and particulate compounds in the freshwater (some of which are mineralized); a lower uptake of phytoplankton indicated by chlorophyll reduction in the estuary; an entrainment of the nutrient-rich upper part of the salt wedge; and, to a lesser extent, the impact of wastewater and agricultural water use. The biggest load discharged into the Mediterranean Sea by the Ebro is nitrogen, followed by silicate with over 10 000 tons of each deposited annually. Phosphorus is discharged at relatively low concentrations and with an annual load of about 200 t yr¿1.This project was funded by the European Union in the framework of the MAST-III research project: "Preparation and Integration of Analysis Tools towards Operational Forecast of Nutrients in Estuaries of European Rivers (PIONEER)", Reference No. MAS3-CT98-0170.Falco Giaccaglia, SL.; Niencheski, L.; Rodilla Alamá, M.; Romero Gil, I.; González Del Rio Rams, J.; Sierra, J.; Mösso, C. (2010). Nutrient flux and budget in the Ebro estuary. Estuarine, Coastal and Shelf Science. 87(1):92-102. doi:10.1016/j.ecss.2009.12.020S9210287

Kemijski profil sedimenata Plominskog zaljeva

Granulometric, chemical, and leaching properties of sediments dredged in the Plomin Bay (Northern Adriatic Sea, Croatia) were investigated in order to asses the risk of remobilisation of heavy metals into the water column. In total 65 samples from 65 sampling sites were taken from different sediment depths within the bay. Analysis of variance confirmed the homogeneity of granulometric and elemental composition of the investigated sediment throughout its volume. Granulometric analysis showed that all samples corresponded to a pelitic fraction (<0.063 mm). Bulk elemental mass fractions in the sediments were similar to literature data on relatively unpolluted areas of the Adriatic Sea. High sedimentation rate caused by constant infl ow of material from the Boljunčica River drainage may be responsible for low levels of heavy metals and negligible infl uence of fl y and bottom ash from a nearby disposal site on the chemical composition of the sediments. In contact with sea water only 0.29 mg kg-1 of V, 0.04 mg kg-1 of Cr, 0.07 mg kg-1 of Ni, 0.33 mg kg-1 of Cu, 0.67 mg kg-1 of Zn and 0.06 mg kg-1 of Pb could be remobilised from sediment material into the water column. However, these values increased three to ten times in case of leaching with organic acids.Granulometrijska i kemijska svojstva te mogućnost otpuštanja teških metala ispitivani su u sedimentima Plominskog zaljeva (Sjeverni Jadran, Hrvatska) u svrhu utvrđivanja rizika od remobilizacije teških metala iz sedimenta u stupac vode. Uzeto je 65 uzoraka s različitih točaka i dubina unutar zaljeva. Analizom varijance potvrđena je granulometrijska i kemijska homogenost cijelog volumena sedimenta, što upućuje na jedan prevladavajući izvor tijekom cijeloga sedimentacijskog razdoblja. Granulometrijskom analizom je utvrđeno da u svim uzorcima prevladava sitnozrnata frakcija (<0,063 mm). Koncentracije elemenata u ukupnim uzorcima sedimenata slične su literaturnim vrijednostima objavljenim za relativno onečišćena područja Jadranskog mora. Velika brzina sedimentacije uzrokovana konstantnim donosom materijala iz slijevnog područja Boljunčice vjerojatan je uzrok niskih koncentracija teških metala i slabo vidljivog utjecaja odlagališta šljake i pepela na sastav sedimenata. U kontaktu s morskom vodom moguća je remobilizacija samo 0,29 mg kg-1 V, 0,04 mg kg-1 Cr, 0,07 mg kg-1 Ni, 0,33 mg kg-1 Cu, 0,67 mg kg-1 Zn i 0,06 mg kg-1 Pb iz sedimenta u stupac morske vode. Ipak ove vrijednosti su tri do deset puta povećane u slučaju izluživanja s pomoću organskih kiselina

Massive Consumption of Gelatinous Plankton by Mediterranean Apex Predators

Stable isotopes of carbon and nitrogen were used to test the hypothesis that stomach content analysis has systematically overlooked the consumption of gelatinous zooplankton by pelagic mesopredators and apex predators. The results strongly supported a major role of gelatinous plankton in the diet of bluefin tuna (Thunnus thynnus), little tunny (Euthynnus alletteratus), spearfish (Tetrapturus belone) and swordfish (Xiphias gladius). Loggerhead sea turtles (Caretta caretta) in the oceanic stage and ocean sunfish (Mola mola) also primarily relied on gelatinous zooplankton. In contrast, stable isotope ratios ruled out any relevant consumption of gelatinous plankton by bluefish (Pomatomus saltatrix), blue shark (Prionace glauca), leerfish (Lichia amia), bonito (Sarda sarda), striped dolphin (Stenella caerueloalba) and loggerhead sea turtles (Caretta caretta) in the neritic stage, all of which primarily relied on fish and squid. Fin whales (Balaenoptera physalus) were confirmed as crustacean consumers. The ratios of stable isotopes in albacore (Thunnus alalunga), amberjack (Seriola dumerili), blue butterfish (Stromaeus fiatola), bullet tuna (Auxis rochei), dolphinfish (Coryphaena hyppurus), horse mackerel (Trachurus trachurus), mackerel (Scomber scombrus) and pompano (Trachinotus ovatus) were consistent with mixed diets revealed by stomach content analysis, including nekton and crustaceans, but the consumption of gelatinous plankton could not be ruled out completely. In conclusion, the jellyvorous guild in the Mediterranean integrates two specialists (ocean sunfish and loggerhead sea turtles in the oceanic stage) and several opportunists (bluefin tuna, little tunny, spearfish, swordfish and, perhaps, blue butterfish), most of them with shrinking populations due to overfishing

Trophic characteristics of the Sapanca lake (Turkey)

Systematic measurements of optical properties, concentrations of major and minor chemicals and primary production throughout 1989-1992 enabled us to identify the oligotrophic state of Sapanca lake, Marmara region, Turkey. Lake waters which have low concentrations of major anions and cations (total = 49 mu M) overturn every February-March, ventilating the bottom waters and enriching the surface waters with nutrients. Surface waters cool down to 6.5 degrees C by late winter and then warm steadily to 26 degrees C by late summer, while temperatures in deep waters range between 6.5 and 10.0 degrees C throughout the year. When the seasonal thermocline develops, the dissolved oxygen profiles exhibit a subsurface maximum in the thermocline, while in the hypolimnion water, the content varies seasonally from 11.5-12.0 ppm (350-375 CIM) in March to 0.5-1.7 ppm (16-56 mu M) in late autumn. Surface nitrate concentrations vary markedly with season, from < 0.15 mu M in summer to 5.7 mu M in early March, whilst the bottom water concentrations range from 13.5-14.0 mu M in late autumn to 5.7 mu M after the winter overturn. Phosphate concentrations are always less than 0.1 mu M throughout the entire water column. Subsurface chlorophyll-a maximum descends in late summer to 20-25 m depths, where the Light intensity is less than 1% of the surface value. Below 10-15 m depths, corresponding to the upper thermocline, primary productivity is very low. The range was from 35 to 93 mg C/m(2) day(-1) during 1989-1991, consistent with the values in other oligotrophic lakes