Management of coastal eutrophication: integration of field data, ecosystem-scale simulations and screening models

Abstract A hybrid approach for eutrophication assessment in estuarine and coastal ecosystems is presented. The ASSETS screening model ( http://www.eutro.org ) classifies eutrophication status into five classes: High (better), Good, Moderate, Poor and Bad (worse). This model was applied to a dataset from a shallow coastal barrier island system in southwest Europe (Ria Formosa), with a resulting score of Good. A detailed dynamic model was developed for this ecosystem, and the outputs were used to drive the screening model. Four scenarios were run on the research model: pristine, standard (simulates present loading), half and double the current nutrient loading. The Ria Formosa has a short water residence time and eutrophication symptoms are not apparent in the water column. However, benthic symptoms are expressed as excessive macroalgal growth and strong dissolved oxygen fluctuations in the tide pools. The standard simulation results showed an ASSETS grade identical to the field data application. The application of the screening model to the other scenario outputs showed the responsiveness of ASSETS to changes in pressure, state and response, scoring a grade of High under pristine conditions, Good for half the standard scenario and Moderate for double the present loadings. The use of this hybrid approach allows managers to test the outcome of measures against a set of well-defined metrics for the evaluation of state. It additionally provides a way of testing and improving the pressure component of ASSETS. Sensitivity analysis revealed that sub-sampling the output of the research model at a monthly scale, typical for the acquisition of field data, may significantly affect the outcome of the screening model, by overlooking extreme events such as occasional night-time anoxia in tide pools.

[1]  J. G. Ferreira,et al.  ECOWIN — an object-oriented ecological model for aquatic ecosystems , 1995 .

[2]  B. H. Ketchum,et al.  Relation Between Circulation and Planktonic Populations in Estuaries , 1954 .

[3]  R. Wetzel,et al.  A Linked Physical and Biological Framework to Assess Biogeochemical Dynamics in a Shallow Estuarine Ecosystem , 1999 .

[4]  M. Pedersen,et al.  Nutrient control of estuarine macroalgae: growth strategy and the balance between nitrogen requirements and uptake , 1997 .

[5]  Cosimo Solidoro,et al.  Modelling macroalgae (Ulva rigida) in the Venice lagoon: Model structure identification and first parameters estimation , 1997 .

[6]  K. Nakata,et al.  A new coastal marine ecosystem model study coupled with hydrodynamics and tidal flat ecosystem effect. , 2001, Marine pollution bulletin.

[8]  F. Martins,et al.  3D modelling in the Sado estuary using a new generic vertical discretization approach , 2001 .

[9]  M.W.M. van der Tol,et al.  Coastal eutrophication and marine benthic vegetation: a model analysis , 1996 .

[10]  P. Duarte,et al.  A functional model of responsive suspension-feeding and growth in bivalve shellfish, configured and validated for the scallop Chlamys farreri during culture in China. , 2002 .

[11]  Carol Janzen,et al.  Eutrophication and some European waters of restricted exchange , 2003 .

[12]  A. Ménesguen,et al.  Hydrodynamic prevention of eutrophication in the Bay of Brest (France), a modelling approach , 1997 .

[13]  R. Neves,et al.  Hydrodynamic and sediment suspension modelling in estuarine systems: Part II: Application to the Western Scheldt and Gironde estuaries , 1999 .

[14]  D. Serpa.  Macroalgal (Enteromorpha spp. and Ulva spp.) primary productivity in the Ria Formosa Lagoon , 2005 .

[15]  H. Lotze,et al.  Control of macroalgal blooms at early developmental stages: Pilayella littoralis versus Enteromorpha spp. , 1999, Oecologia.

[16]  G. Billen,et al.  Coastal eutrophication of the Southern Bight of the North Sea: Assessment and modelling , 1997 .

[17]  Sven Erik Jørgensen,et al.  A eutrophication model for a lake , 1976 .

[18]  David J. Hydes,et al.  Development of a 2D horizontal biogeochemical model for the Irish Sea DYMONIS , 2000 .

[19]  S. Bäck,et al.  Survey of macroalgal mats in the Gulf of Finland, Baltic Sea , 2001 .

[20]  J. Hauxwell,et al.  Macroalgal blooms in shallow estuaries: Controls and ecophysiological and ecosystem consequences , 1997 .

[21]  João Ricardo Silva,et al.  Ria Formosa 3D hydrodynamic model. A contribution for the understand- ing of the Faro-Olha o inlet processes , 2002 .

[22]  I. Martins,et al.  A model for the growth of opportunistic macroalgae (Enteromorpha sp.) in tidal Estuaries , 2002 .

[23]  S. Bricker,et al.  National estuarine eutrophication assessment: effects of nutrient enrichment in the nation's estuaries , 1999 .

[24]  J. Finn,et al.  Nitrogen loading alters seagrass ecosystem structure and support of higher trophic levels , 2002 .

[25]  J. Nunes,et al.  Evaluation of eutrophication in the Ria Formosa coastal lagoon, Portugal , 2003 .

[26]  S. Bricker,et al.  An integrated methodology for assessment of estuarine trophic status , 2003 .

[27]  S. Chapra.  Surface Water-Quality Modeling , 1996 .

[28]  J. Rivers,et al.  Contribution by Macroalgal Mats to Primary Production of a Shallow Embayment Under High and Low Nitrogen-loading Rates , 1996 .

[29]  M. Pedersen,et al.  Nutrient control of algal growth in estuarine waters: Nutrient limitation and the importance of nitrogen requirements and nitrogen storage among phytoplankton and species of macroalgae. , 1996 .

[30]  V. Brotas,et al.  Oxygen profiles in intertidal sediments of Ria Formosa (S. Portugal) , 1990, Hydrobiologia.

[31]  Adriano Sfriso,et al.  Simulation model of Ulva rigida growth in shallow water of the Lagoon of Venice , 1997 .

[32]  P. Tett,et al.  The PROWQM physical–biological model with benthic–pelagic coupling applied to the northern North Sea , 2002 .

[33]  Attilio Rinaldi,et al.  Characterization of the trophic conditions of marine coastal waters with special reference to the NW Adriatic Sea: proposal for a trophic scale, turbidity and generalized water quality index , 1998 .

[34]  Andreas Moll,et al.  Review of three-dimensional ecological modelling related to the north sea shelf system. Part II: Model validation and data needs , 2003 .

[35]  J. L. Pérez-Lloréns,et al.  Photoacclimation of Ulva rigida and U. rotundata (Chlorophyta) arranged in canopies , 1998 .

[36]  C. Vale,et al.  Sediment–water exchanges of ammonium and phosphate in intertidal and subtidal areas of a mesotidal coastal lagoon (Ria Formosa) , 2004, Hydrobiologia.

[37]  J. Ferreirab,et al.  Modelling eutrophication in mesotidal and macrotidal estuaries . The role of intertidal seaweeds , 2003 .

[38]  P. Dillon,et al.  A Simple Method for Predicting the Capacity of a Lake for Development Based on Lake Trophic Status , 1975 .

[39]  J. Widdows,et al.  Influence of hypoxia and anoxia on the physiological responses of the clam Ruditapes decussatus from southern Portugal , 1997 .

[40]  João Pedro Nunes,et al.  A model for sustainable management of shellfish polyculture in coastal bays , 2003 .

[41]  M. Sprung.  Macrobenthic secondary production in the intertidal zone of the ria Formosa: a lagoon in southern Portugal , 1994 .

[42]  K. Havens,et al.  Complex interactions between autotrophs in shallow marine and freshwater ecosystems: implications for community responses to nutrient stress. , 2001, Environmental pollution.

[43]  Hugh L. MacIntyre,et al.  Primary production by suspended and benthic microalgae in a turbid estuary: time-scales of variability in San Antonio Bay, Texas , 1996 .