River discharge into the Mediterranean Sea and estimation of the associated nutrient load Task O.G.S.: Alessandro Crise, Cosimo Solidoro, Sebastiano Trevisani ENEA: Salvatore Marullo, M.Vittoria Struglia CIRCE MEETING Bologna, 2 May 2007

Summary Statement of the problem Statement of the problem Aims of the task Aims of the task Description of planned activities Description of planned activities

A view of the Mediterranean sea Sea - Wifs image from EEA Topic Report

Two sides of the same coin: Eutrophication and Oligotrophication Two sides of the same coin: Eutrophication and Oligotrophication Eutrophication refers to an increase in the rate of supply of organic matter to an ecosystem, which most commonly is related to nutrient enrichment enhancing the primary production in the system (Nixon, 1995). Eutrophication refers to an increase in the rate of supply of organic matter to an ecosystem, which most commonly is related to nutrient enrichment enhancing the primary production in the system (Nixon, 1995). Oligotrophication is the reversal of the eutrophication process and can occur as the result of changes in precipitation and runoff regime or of operation of advanced waste treatment facilities on inflowing rivers Oligotrophication is the reversal of the eutrophication process and can occur as the result of changes in precipitation and runoff regime or of operation of advanced waste treatment facilities on inflowing rivers

Impacts of eu/oligo-trophication changes in the structure and functioning of the marine ecosystems; reductions in biodiversity; reductions in the natural resources of demersal fish and shellfish; reduced income from maricultures of fish and shellfish; reduced recreational value and income from tourism; increased risk of poisoning of animals including humans by algal toxins.

The nutrients’ load We focus our analysis on nutrients carried by rivers as causes of eutrophication/oligotrophication. Total nutrient loads can be estimated by the time integration of instantaneous fluxes Total nutrient loads can be estimated by the time integration of instantaneous fluxes C x Q (nutrient concentration x river discharge) The temporal variability of river discharge is a dominant factor in this process The temporal variability of river discharge is a dominant factor in this process

Our aims 1. Evaluate the impacts of interannual and decadal variability of river discharge on the marine environment and ecosystem under current climate conditions 2. Attempt a description of the impact that climate changes may have onto the nutrient loads.

Our plan An empirical model will be developed based on: An empirical model will be developed based on: - land use information - land use information - nutrient retention and loss within river system - nutrient retention and loss within river system - river discharge data - river discharge data A limited number of river basins, possibly representative of the response of the European and African coasts, will be selected as case studies. A limited number of river basins, possibly representative of the response of the European and African coasts, will be selected as case studies. Results from this model will be compared with available observed (satellite or in-situ) quantities linked to riverine nutrient load. Results from this model will be compared with available observed (satellite or in-situ) quantities linked to riverine nutrient load.

Total nutrient load can be evaluated by means of different methodologies characterized by different degrees of complexity. For example for the Rhone T. Moutin et Alii made the evaluation considering water flux and nutrients concentration. Then, in the case of Nile, S. Nixon evaluated nutrients load taking in to consideration the population, sewage systems and fertilizer use. T. Moutin et Alii, 1998, “The input of nutrients by the Rhone river into the Mediterranean Sea: recent observation and Comparison with earlier data”, Hydrobiologia, pp S.W. Nixon, 2003, “Replacing the Nile: Are Anthropogenic Nutrients Providing the Fertility Once Brought to the Mediterranean by a Great River”, Ambio, Vol.32, No. 1. Land use and nutrient load

Reasonably, in order to perform a scenario based analysis (climate change, demographic variations, different land use, etc.) there could be the need of numerical models (SWAT, MONERIS, POLFLOW, POL, as an example) able to simulate the temporal variation in nutrients load related to the set of physical and chemical processes involved. The choice of the model to be used is related to the hydrological characteristics of the basin, to the data available and to the target of our analysis. Likely these models should be linked or integrated in to a geographical information system S.L. Neitsch, J.G. Arnold, J.R. Kiniry and J.R Williams, 2005, “Soil and Water Assessment Tool Theoretical Documentation”, Texas. M. Tournoud, S. Payraudeau, F. Cernesson and C. Salles, 2005, “Origins and quantification of nitrogen inputs into a coastal lagoon: application to the Thau lagoon (France)”, Ecological Modelling, 193, pp M.J. M. de Wit, 2000, “Nutrient fluxes at the river basin scale. I: the PolFlow model”, Hydrological processes, 15, pp L. Palmeri, G. Bendoricchio and Y. Artioli, 2005, “Modeling nutrient emissions from river systems and loads to the coastal zone: Po river case study, Italy”, Ecological Modeling, 184, pp

River discharge data Current climate: historical time series from several on- line database (GRDC, MMA, Med-Hycos, sage, UNESCO) are available and will be analyzed respect to climatology and interannual and decadal variability: Current climate: historical time series from several on- line database (GRDC, MMA, Med-Hycos, sage, UNESCO) are available and will be analyzed respect to climatology and interannual and decadal variability: River Years available Rhone Po Ebro Moulouya Climate change: informations from other RL’s are expected Climate change: informations from other RL’s are expected

Contribution of major rivers to total runoff

Interannual variability in the Adriatic Sea and in the Gulf of Lion. From Struglia et al. Journal of climate, 2004

In a first instance three Mediterranean rivers will be considered: Rhone, Po and Nile (these cover around 1/3 of the total riverine input into the Mediterranean Sea) In order to understand these rivers and their relations with the sea two aspects should be considered:  hydrologic and hydrochemical behaviour of the rivers  hydrochemical characteristics and spatio-temporal variation of marine coastal waters in the proximity of estuaries

Validation of the model In situ measures Ocean color satellite data

Chlorophyll climatology by SEA-WIFS Open ocean optical remote sensing of the Mediterranean Sea by R. Santoleri, G. Volpe, S. Marullo, B. Buongiorno Nardelli to appear on the book "Remote sensing of the European Seas"

Seasonal and year to year variability can be studied using time series of ocean color satellite data. SeaWiFS data permit to investigate the variability of the Chlorophyll field (or other ocean color derived parameters) in the Adriatic Sea for the period from 1998 to today. April Courtesy of ADRICOSM NERES project and ENEA