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					SESSION 7 UNIFYING CONCEPTS IN COASTAL ECOLOGY AND MANAGEMENT

European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

SESSION 7

158

Oral Presentation

European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

F-ECTS: OVERALL SUMMARY OF THE PROJECT A. Bergamasco
IST, National Research Council, Spianata S. Raineri, 98122, Messina, Italy

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

SESSION 7

160

Oral Presentation

European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

1. F-ECTS - MONITORING THE CONCEPTUAL SCHEMATIZATION OF AN ESTUARINE SYSTEM FOR THE INVESTIGATION OF THE INTERACTIONS AMONG PHYSICAL AND ECOLOGICAL PROCESSES Bergamasco A. 1, L. De Nat2, K. Millard3, M. Flindt4, C. Amos5 , P. Ciavola6
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IST, National Research Council, Spianata S. Raineri, 98122, Messina, Italy Thetis SpA, Castello 2737/f, 30122 Venice, Italy HR Wallingford, Wallingford, England Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK Dipartimento di Scienze della Terra, Università di Ferrara, C.so E. I d’Este 32, 44100, Ferrara, Italy

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS F-ECTS main focus is the interdisciplinary investigation of the ecosystem loops in estuarine environments involving phytobentos communities, hydrodynamics, nutrient cycling and sediment transport. The Lagoon of Venice (Italy) was considered as the pilot site for the in-situ investigation of the above phenomena through the carrying out of two seasonal field campaigns, aiming at the parameterization of the main physical and biological processes of the ecosystem. Following such investigation, a mathematical model of the feed-back links between phytobenthos and sediment transport was to be produced improving and putting together existing hydrodynamic, phytobenthos growth and sediment transport modules. To support this research flow and as a first step towards modelling, a provisional state-of-the-art conceptual scheme describing the structure of an estuarine ecosystem and its functioning was set up at the beginning of the project, according to the present knowledge of biogeochemical and physical phenomena, and tailored to the Lagoon of Venice. This also in order to drive the identification of the key parameters to be measured during the field campaigns. Following a preliminary analysis of the new experimental data sets, the provisional conceptual scheme of the Lagoon of Venice ecosystem set up at the beginning of the project has been reviewed in detail in the light of the new experimental findings and adjusted/modified to produce the extended conceptual scheme of the Lagoon of Venice ecosystem which has been used as a basis for the development of the new model. The paper describes such conceptual scheme and discuss the possibility to extend its adoption to approach the study of other estuarine ecosystems.

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161

Oral Presentation

European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

FEEDBACK MECHANISMS BETWEEN HYDRAULICS, NUTRIENT EFFLUX AND BENTHIC MICROBIAL ACTIVITY M.R. Flindt 1, C. Amos 2, A Bergamasco 3 and C. B. Pedersen 4
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Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark, e-mail: mrf@biology.sdu.dk SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK Thetis SpA, Castello 2737/f, 30122 Venice, Italy Freshwater Biological Laboratory, University of Copenhague, Helsingørsgade 51, dk-3400 Hillerød, Denmark

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS In the context of the F-ECTS fieldwork in the Lagoon of Venice 20 stations of varying bed properties (grain size, water content, organic content, dissolved inorganic profiles and macrophyte composition, and biomass) were occupied by the benthic flume Sea Carousel. Current speed was increased in increments of 10 cm s-1 within the flume. At each increment, water samples were collected through pumping while measures of turbidity, turbulence, and mean flow were made. Thus, it was possible to determine the hydrodynamic effect on the efflux of dissolved inorganic nutrients measured in pumped samples as well as the benthic bacterial activity and benthic diatom production. Effluxes of ammonia, nitrate, nitrite, phosphate, and dissolved organic carbon from the sediment porewater were measured through increases in water column concentration. As well, the benthic heterotrophic bacterial activity was measured by adding INT pumped samples. The bacterial respiration was terminated after 30 minutes by addition of H2 SO4. Benthic diatom production was measured traditionally by the addition of 14C; incubations were also halted after 30 minutes by addition of H 2SO4. The bed shear stress was strongly reduced by the presence of rooted vegetation (Cymodocea sp. and Zostera marina), and it was not possible to resuspend the underlying sediment. By contrast, beds free of vegetation or colonised by macroalgae were much easier to erode. The highest increases in absolute and specific activity of bacteria and algae were also measured at these sites. Epiphytes on the leaves of the rooted vegetation were sloughed at high flows and contributed to the measurements of carbon. Bacterial activity and benthic microalgae production increased with water velocity over bare bottoms. The increase ranged from 2 to 20 times the still water condition, and resulted mainly from resuspension of biomass. Normalising for changes in biomass showed that the specific activities also increased.

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162

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

These were from 2 to 7 times higher than the still water condition. Where the highest specific rates occurred, the benthic microalgae were growth limited by light and PO 4 and the benthic bacteria were limited by easily degradable carbon sources (DOC). So resuspension and the resulting effluxes of nutrients and dissolved organic carbon stimulated the enhanced benthic biological activities.

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163

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

MEASUREMENTS OF MACROPHYTE GROWTH AND LOSS RATES AND NUTRIENT FLUXES IN A SUMMER AND A WINTER FIELD CAMPAIGN IN THE LAGOON OF VENICE Pedersen C.B.1, M.R. Flindt2, M. Pardal3 , J. Neto3, A. Bergamasco4
(1)

Freshwater Biological Laboratory, University of Copenhague, Helsingørsgade 51, dk-3400 Hillerød, Denmark Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark IMAR, Zoological Department, University of Coimbra, Portugal Thetis SpA, Castello 2737/f, 30122 Venice, Italy

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A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS At nine stations in the Lagoon of Venice measurements of plant growth and loss rates were done together with nutrient fluxes between the sediment and water column. The measured fluxes included: Ammonia, nitrate, nitrite, dissolved organic nitrogen, dissolved organic carbon, phosphate and oxygen. The stations varied with respect to sediment properties (grain size, water content, pools of carbon, nitrogen and phosphorus) and dominating plant species (Cymodocea sp., Zostera marina, Zostera noltii, and Ulva sp.). The measured plant loss rates included grazing, sporulation and advective transport. Macrophyte growth rates varied between 0.02-0.18 d-1 , while loss rates by grazing ranged from 0.02 to 0.05 d-1 and sporulation ranged from 0.00 to 0.17 d-1 . In the summer campaign the net loss rates exceeded the growth rates at several stations especially during spring tide periods where rooted vegetation sloughed leaves do to high current velocities while unattached opportunistic macroalgae were resuspended and transported away. Sediment oxygen dynamic varied between daytime oxygen production of 40 mg O2 m-2 h-1 and nighttime oxygen consumption of 200 mg O2 m-2 h-1 . The sediment ammonia fluxes varied from -2 mg NH4 -N h-2 d-1 to 18 mg NH4-N m-2 h-1 , while phosphate fluxes varied between -0.25 mg PO4 -P m-2 h-1 to 1 mg PO4 -P m-2 h-1. Summer nitrification and denitrification were closely related to the biomass of rooted vegetation. Net mass balances at the stations showed huge variation in the nutrient pathways. Some stations were dominated by the heterotrophic processes resulting in huge nutrient effluxes, while other stations were dominated by nutrient uptake by macrophytes and relatively small effluxes. In general, stations dominated by rooted macrophyte released less nutrients than stations without, and the oxygen dynamics were much more balanced.

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164

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

PLANT BOUND NUTRIENT TRANSPORT – A NEGLECTED PART OF THE NUTRIENT MASS BALANCE – IN ESTUARIES Flindt M.R 1, C. B. Pedersen 2 , M. Pardal 3 , A Bergamasco 4 , C. Amos 5
(1)

Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark (mrf@biology.sdu.dk) Freshwater Biological Laboratory, University of Copenhague, Helsingørsgade 51, dk-3400 Hillerød, Denmark IMAR, Zoological Department, University of Coimbra, Portugal Thetis SpA, Castello 2737/f, 30122 Venice, Italy SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK

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A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS A major observation has been that nutrient export from estuaries during the growth season takes place as drifting macro algae and macro detritus. During a summer campaign in the Lagoon of Venice more than 90% of the nutrient export (nitrogen and phosphorus) was bound in plant material, while about 20-30% of the nutrient export from the Danish Roskilde Fjord was linked to plant transport. Even in the winter season, the plant and macro detritus associated nutrient export accounted for about 25% of the total nutrient export. The transport patterns of different plants vary. Some plants were transported as bedload (Chaetomorpha sp.) while other species were transported either in the water column (Ulva sp.) or floating at the surface (leaves from the rooted vegetation). Measurements at the outer boundary verified that less than 20 % of the exported plant matter returned to the Lagoon of Venice and in most cases it was even less than 5 %. High settling rates of 500-2000 md-1 explained why only small amounts of plant material returned to the Lagoon as they settle to the bed of the inner Adriatic Sea at the end of the ebb tide. In conclusion, this extra nutrient transport mechanism has an impact on the mass balance calculations in coastal areas, which sometimes may have been underestimated.

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165

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

THE ROLE OF MACROPHYTE DEBRIS MOVING AS BEDLOAD ON THE BENTHIC FLUX – TWO FEEDBACK MECHANISMS IN A SEASONALLY CONTROLLED BALANCE Amos C.1., M.R. Flindt2 , A. Bergamasco3 A. Levy4
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School of Ocean and Earth Science, Southampton Oceanography Centre, Empress Dock, Southampton, UK (cla8@soc.soton.ac.uk) Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark Thetis SpA, Castello 2737/f, 30122 Venice, Italy Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS Two intensive field campaigns within Venice Lagoon were carried out within the EU-funded F-ECTS project (Amos et al., 2000). Two in situ benthic flumes (Sea Carousel and Mini Flume) were used to simulate resuspension of organic matter, sediment and nutrients under controlled conditions of flow. Fast settling organic matter was ubiquitous and exhibited threshold velocities for motion of 0.02 m/s. This material contributed substantially to the benthic flux through the solid-transmitted stresses caused by saltation. Further laboratory experimentation in a laboratory equivalent of Sea Carousel were carried out using the macrophyte Ulva sp. These results showed increases in erosion rate by a factor of 20 over the fluid-induced erosion rates; a much lower threshold for the onset of resuspension was found than was the case for a purely fluid-transmitted stress (Levy, 2000). Furthermore, the erosion began at the onset of motion of the macroalgae. This threshold was largely dependent on the sinking rate of the organic debris, and, surprisingly, independent of the properties of the bed. The rate of erosion was dependent on the area concentration of material over the bed, and appeared to be independent of shape or size of the plant material (Cosette, 2000). This mechanism was the dominant control of the benthic flux when area concentration of debris exceeded 5%. Thus we may conclude that below 5% cover, the fluid-transmitted stress prevails and the properties of the bed are important: above 5% debris cover the solid-transmitted stress prevails and the properties of the debris are important. The important sediment-macrophyte feedback mechanisms evident from this work are as follows: fixed macrophytes grow on the muddy substrate of Venice Lagoon (barene); the macrophytes stabilise the bed through sheltering (the first feedback mechanism); macrophyte debris is sloughed by wind-wave-current erosion; the debris enhances the efficiency of bed/macrophyte erosion (the second feedback mechanism); decreases in macrophyte cover reduces the solid-transmitted stresses thereby establishing a dynamic balance which is probably seasonally controlled.

SESSION 7

166

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

References Amos, C.L., Cloutier, D., Cristante, S. and Cappucci, S. 2000. The Venice Lagoon Study (F-ECTS), Field Results – February, 1999. Geological Survey of Canada Open File Report 3904. Levy, A. 2000. The role of mobile macroalgae on the erosion of cohesive sediments. Unpublished M.Sc. Thesis, Acadia University, Wolfville: 137p.

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167

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

IN-SITU ASSESSMENT OF SEDIMENT STABILITY IN INTERTIDAL AREAS: MEASUREMENT OF BIO-DEPENDENT BED PARAMETERS AS A PROXY TOOL Ciavola P.1, P. Friend2, S. Cappucci2, and C. Amos2
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Dipartimento di Scienze della Terra, Università di Ferrara, C.so E. I d’Este 32, 44100, Ferrara, Italy (cvp@unife.it) SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK

(2)

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS The assessment of critical erosion thresholds in intertidal areas is of extreme importance for studies of the feed-back mechanisms between biostabilisation of sediment and current regimes, at estuarine sites. The feed-back process has practical implications for the artificial recreation of mudflats using dredged material, and for the evaluation of habitat loss following accidental pollution events. As part of the F-ECTS Project, within the ELOISE framework, a field study of these mechanisms was undertaken in the Lagoon of Venice in northern Italy. Two campaigns were conducted, in summer 1998 and in winter 1999, in which the annular flumes, Sea Carousel and Mini Flume, were deployed from a movable jack-up barge. In order to have a comprehensive view of the small-scale variability in erosion thresholds at an intertidal site (Palude della Centrega), a portable instrument, the Cohesive Strength Meter (CSM), was also used. There was close agreement between the results obtained using Sea Carousel and those from Mini Flume; biostabilisation and erosion thresholds in the summer were greater, by almost a factor of two, compared with winter values. Biostabilisation at the Centrega site was due mainly to a biofilm of filamentous brown algae present at the edge of a main channel. Spatial variability studies using the CSM on the mudflat, identified that sediment stability was directly related to elevation; stability was higher at the edge of tidal creeks than within sea-grass communities living on the lower mudflat. In order to test the exportability of the results obtained from the fieldwork in Venice, two further sets of experiments were undertaken in September 2000 and March 2001 in the Ria Formosa Lagoon, in southern Portugal. On these occasions, the CSM was the only erosion device to be deployed; this choice was dictated by its relative ease of transportation, as well as its widespread usage elsewhere in other sedimentological and ecological field studies, including the EU funded projects, INTRMUD, BIOPTIS, ECOFLAT. The site selected was a mixed habitat, intertidal site near the Ramalhete Channel, in the western part of the lagoon; here, a total of 32 stations were sampled in four cross-shore transects. A strong relationship was found between habitat type and erosion threshold; and between colloidal carbohydrate and chlorophyll a content, and (to a lesser extent) bed elevation. SESSION 7
168

Oral Presentation

European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

Generally, erosion thresholds decreased seawards, reflecting a change in habitat type from cyanobacterial mats in the upper shore, through Spartina then Zostera beds, to a silty/sandy substrate of the main channel sides. In the first campaign, filamentous cyanobacteria were the dominant microphytobenthic stabilisers of sediment. HPLC analysis of the sediments, showed the increasing presence towards the lower shore, and particularly on the channel sides, of diatoms. However, any stabilising effect by the diatoms was insignificant, compared with that of the cyanobacterial mats. The sandy channel sides appeared to become more stable, after the passage of a high-energy wind (and wave) event, possibly due to an increase in epipelic diatom activity. In the second campaign, cyanobacterial activity was low. Instead, a filamentous Enteromorpha spp. had apparently replaced the cyanobacterial mats as the main sediment stabiliser; this process has not been observed previously. Statistical relationships between erosion thresholds, bed level elevation, colloidal carbohydrate and chlorophyll a will be presented from the two sites and their possible exportability to other locations and habitats will be discussed.

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169

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

CUSTOMIZED, LOW-COST AND HIGH RESOLUTION SPECTRAL DATA FOR MODELLING IN THE COASTAL ZONE Millard K.1, J. Monk 2 , A. Brady 1
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HR Wallingford, Wallingford, England University of Dundee, Dundee, Scotland

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS Many scientists and engineers working in the field of environmental management have realised the benefits of using remote sensing techniques for providing wide-area spatial data. The increases over recent years in both the spectral and spatial resolution of available data has resulted in remote sensing techniques being clearly demonstrated as offering the potential to effectively support environmental management. Coastal Zone Management however remains one area where this promise is yet to be fully realised.Coastal Zone Management (CZM) requires data of both high spatial resolution and high spectral resolution. This data also needs to be provided at low-cost. Satellite data on the most part can meet this low-cost and high-spectral resolution demands, but the requirement of high spectral and spatial resolution can only be offered at present by airborne instruments such as CASI. These sophisticated techniques are expensive to commission and require specialist aircraft to operate. Accordingly they tend to be operated by government agencies and national environmental bodies.There is a demand therefore for low cost remotely sensed data of both high spatial and spectral resolution that can be collected to solve particular management issues or scientific research in the coastal zone. This paper presents the results of the practical application of one such approach using an instrument known as VIFIS.

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

This instrument is based on commercial video-camera technology and can be used on most aircraft platforms, collecting data at a much lower costs than instruments such as CASI.This paper describes applying VIFIS to collect data on suspended particulate matter (SPM) and chlorophyl-a in the Venice Lagoon for the purpose of numerical modelling. The aim of the numerical modelling is to better understand the relationship between sediment transport and phytobenthic growth in the region. This paper explains the processing involved from data collection to the delivery of processed data suitable for use in a particular numerical model. Particular attention is made to analysis of the costs incurred during this process compared to the value of the data as input to the numerical modelling processes and in understanding the SPM and phytobenthic regimes in the Venice Lagoon.

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171

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

2. F-ECTS - MODELING THE SPM PHYTOBENTHOS-REACTION MODEL FOR ESTUARINE ECOSYSTEMS AND ITS APPLICATION TO THE VENICE LAGOON PILOT SITE Rolinski S.1 , G. Umgiesser 2, M. Flindt3 and C. Amos 4
(1) (2) (3)

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Instituti fuer Meereskunde, University of Hamburg, Germany, ISDGM, National Research Council, Venice, Italy Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS Feedbacks between estuarine circulation and transport of sediments on phytobentos are the main focus of the F-ECTS project in the framework of the European MAST III Programme. Modelling the hydrodynamics and the transport of suspended particulate matter (SPM) in the Venice Lagoon was to be combined with simulations of the dynamics of phytobenthic algae. The 3D finite element hydrodynamical model of Venice Lagoon uses real-time forcing for tidal elevation and atmospheric data, producing mass, current, salinity and temperature fields for the subsequent simulation of the transport of SPM. A newly conceived interpolation mechanism transforms the relevant parameters from the irregular finite element grid on to a regular finite difference grid, on which the SPM model is formulated. Mass consistency between the resulting transport and water elevation fields is guaranteed. Particulate material originating both from mineral and organic origin are traced following the Lagrangian concept. Besides the transport due to advection, diffusion and sinking, exchange of material with the sediment is implemented in terms of erosion and deposition. Benthic organisms are assumed to redistribute fine grains in the sediment and thus, influence erodibility of sediments. The dynamics of biological components such as algae (Ulva Sp.) and detritus and a dissolved nutrient are simulated according to the well-known concept of three components ecological models. Physical and biological processes are linked by two mechanism. Turbidity due to SPM concentrations reduces the available light for photosynthesis of algae so that their growth decreases. On the other hand, abundance of algae influences the formulation of erosion. The actual depth, into which the erosion event reaches, decreases where algae are numerous. Results of simulations during the summer campaign in August 1998, comparing runs with the physical and biological modules separately and combined, are discussed.

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

EXPORTING THE PHYTOBENTHOS-REACTION MODELING APPROACH: ROSKILDE FJORD CASE STUDY Umgiesser G.1 , M. Flindt2, C. Amos3 and A. Bergamasco4
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ISDGM, National Research Council, Venice, Italy (georg@isdgem.ve.cnr.it) Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK Thetis SpA, Castello 2737/f, 30122 Venice, Italy

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS A finite element hydrodynamic model has been applied in the framework of the European project F-ECTS to the Roskilde Fjord in Denmark. The fjord is a bay about 35 km long and about 10 meters deep. Along its coast numerous cities are situated and various touristic and commercial activities are going on. The hydrodynamic model is the same as the one used in the study for the Venice Lagoon. The model uses linear triangular elements in the horizontal and fixed layers (z-coordinates) in the vertical. The time-integration is accomplished by a semi-implicit method that allows for longer time steps that are not constrained by the gravity wave stability criterion. The hydrodynamic model solves also the transport and diffusion equation. This module is used for physical quantities such as temperature and salinity and the ecological state variables that are solved in parallel with the physical quantities and are fully integrated into the code of the hydrodynamic model. In this way the feedback of the physical quantities (sediment concentration) can be accounted for in the ecological model (light shading on benthic vegetation).The ecological model contains 23 state variables that simulates the carbon, nitrogen and phosphorus forcing, pools, processes and dynamics. The model has been developed independently in the computer language PowerSim. From the PowerSim printout a Fortran version has been produced with the help of Perl and Python modules. This Fortran version has been directly included into the hydrodynamic code of the Roskilde model.The model has been run for one whole year to reproduce the interannual variability. Real forcings have been prescribed for the hydrology, meteorology and water quality. Results of the ecological model are presented.

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

ARE ALL THE INTERTIDAL FLATS IN VENICE LAGOON DISAPPEARING? Cappucci S.1 , C. Amos1 and G. Umgiesser2
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School of Ocean and Earth Science, Southampton Oceanography Centre, Empress Dock, Southampton, UK SO14 3ZH (sc14@soc.soton.ac.uk) ISDGM, National Research Council, S. Polo 1364, 30125 Venice, Italy

(2)

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS The diverse and fertile tidal flats fringing Venice Lagoon have been in chronic decline over the last 100 years. If this continues, the tidal flats will disappear by 2040. This study has attempted to examine the potential factors responsible for habitat loss through a study, which couples field measurements over a period of 2 years with a 1-D numerical simulation of tidal flat evolution. The questions we were attempting to answer were: (1) to what extent does river inflow impact the observed sedimentation trends , and (2) to what extent are these trends influenced by (i) storms, (ii) vegetation cover, (iii) residence times of sediment within the Lagoon, and (iv) sediment stability (v) and inundation depth (subsidence / sea level rise). The study was undertaken within the EU project F-ECTS the objectives of which were to examine the role of macrophyte distribution and species on tidal flat evolution. The work presented here is focussed on an intertidal mudflat to the north of Venice (Palude della Centrega). The site is one of the few in accretion within the Lagoon (1.6 cm/year). The net changes in bed level were measured at 13 sites across the tidal flats which vary in elevation, physical properties and cover of the sea grass during Summer time. As well, the erosion thresholds, erosion rates, minimum shear stress for deposition and deposition rates were evaluated using in situ benthic flumes (Mini Flume) coupled with laboratory experiments. Chlorophyll and carbohydrate contents were measured along with bulk density, sediment grain size and organic content in an attempt to adequately characterise each site. The sensitivity analysis of the model showed that the combined effect of shear stress reduction (by sea grass) and input of sediment dominate the observed deposition trends on the tidal flat.

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

SIMPLIFIED MODELING APPROACHES TO SUPPORT THE EVALUATION OF SITE-SPECIFIC RELEVANT PROCESSES: RIA FORMOSA CASE STUDY Silva A.1 , J. Leitão1, R. Santos2 , P. Ciavola3
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Hidromod Modelacao em Engenharia, Portugal UCTRA, Universidade do Algarve, Campus de Gambelas, 8000 Faro, Portugal Dipartimento di Scienze della Terra, Università di Ferrara, C.so E. I d’Este 32, 44100, Ferrara, Italy

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS Ria Formosa lagoon (Southern Portugal) covers a region about 55 km long corresponding to the limits of five barrier islands that protect the lagoon against the direct action of the sea. In the framework of Mast III F-ECTS project, Ria Formosa lagoon was selected as specific investigation sites to evaluate the exportability of some major results concerning the feed-backs that couple the establishment of phytobenthic communities and the physical parameters, obtained for the pilot project site: the Venice lagoon. To support these actions, a limited field-work activity concerning the characterization of the local currents, the macrophyte distribution, leaf release and transport rates and bed erodibility was carried out. An hydrodynamic model and a lagrangian transport model of Ria Formosa lagoon were set up in order to enable the integration of the field-data and the interpretation of the local transport processes. The model resulted from an implementation of the MOHID modelling system. The hydrodynamic model was calibrated using the currents and the water levels field data. The lagrangian transport model was used to follow the macrophyte paths and to evaluate the macrophyte mass exported outside the lagoon, taking into consideration different tide and wind conditions. In this paper the results of Ria Formosa lagoon hydrodynamic and lagrangian transport models will be presented and compared with the available field data concerning the hydrodynamics and the macrophyte distribution.

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4th ELOISE Conference 5-7 September 2001, Rende, Italy

3. F-ECTS - TOOLS FOR MANAGEMENT MAPPING THE “ECOLOGICAL SUITABILITY” WITHIN AN ESTUARY Bergamasco A. 1, L. De Nat2, M. Flindt3 , S. Rolinski4 , G. Umgiesser5 , C. Amos6
(1) (2) (3) (4) (5) (6)

IST, National Research Council, Spianata S. Raineri, 98122 Messina, Italy Thetis SpA, Castello 2737/f, 30122 Venice, Italy Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark Institut fuer Meereskunde, University of Hamburg, Germany ISDGM, Natrional Research Council, S.Polo 1364, 30125 Venice, Italy SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS Feed-backs between estuarine circulation and transport of sediments on phytobentos are the main focus of the F-ECTS project in the framework of the European MAST III Programme. One of the main goals of the project was to demonstrate the combined use of in-situ measurements and model results in the context of a GIS-based application and its transfer into a practical tool for supporting the evaluation of CZM actions in complex systems such as estuarine areas. The experience and methodologies achieved during FECTS in setting up a procedure for the comparison of different scenarios suggest that central in this evaluation process is the possibility to map the changes of the “ecological suitability” within the estuary with respect to the presence and/or the development of phytobenthos. To address this issue the main requirement is the possibility to classify the environment according to the persistence of a given “state” resulting from the combination of several forcing processes, both physical and ecological. Examples of these classification criteria are: duration of submersion versus emersion phases; overshooting of the local erosion threshold and duration of the erosive phase in a tidal cycle; persistence of SPM and/or nutrients above or below a fixed threshold. A synthetic description of the newly developed GIS-based tools is presented and evaluated through a Venice Lagoon case study. In particular management questions such as (i) “Where and how long does the current velocity overcome local erosion threshold ? Is this pattern related to grain size or phytobenthos distribution?” or (ii) “Where and how long is light climate the limiting factor for the phytobenthos growth?” or (iii) “To what extent are released dissolved inorganic nutrients becoming assimilated or dispersed around in the estuary?” can be specifically addressed.

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

BOOKLET PART I: GUIDELINES FOR INTEGRATED MODEL-ORIENTED MONITORING OF ESTUARINE ECOSYSTEMS Bergamasco A. 1, L. De Nat2, M. Flindt3 , S. Rolinski4 , G. Umgiesser5 , C. Amos6
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IST, National Research Council, Spianata S. Raineri, 98122 Messina, Italy Thetis SpA, Castello 2737/f, 30122 Venice, Italy Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark Institut fuer Meereskunde, University of Hamburg, Germany ISDGM, Natrional Research Council, S.Polo 1364, 30125 Venice, Italy SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS The specific experience developed in the context of the project F-ECTS concerning the interdisciplinary approach to the study of an estuarine ecosystem has been translated into a Booklet of integrated guidelines. In particular Part I of the Guidelines describes this approach relying on a three-pier architecture: (1) the conceptualisation of the system to be studied, mainly focusing to the feed-backs between the physical subsystem and the ecological one, (2) the monitoring activity, specifically oriented to selectively generate field data able to support (3) the joint dynamical modelling of hydrodynamic, sediment transport and ecological processes. The main requirements of the monitoring programme to be set up are identified and described on the basis of a generalized conceptual scheme, developed and refined for the Lagoon of Venice. The essential links and processes recognized through the preliminary screening of the system are taken into account, such as basic hydrographic forcings, external loadings, internal nutrient loadings and dynamics, SPM concentration, erosion/deposition thresholds, status of the biological structures; requirements and constraints depending both on the using of these data for modelling purposes and on field-related aspects are highlighted. The basic assumptions of the suggested modelling approach to be adopted are presented in detail, with particular reference to the selection of the scenarios to be modelled. Criteria to select boundary conditions, duration of simulations, parameters to be followed with respect to the target of the analyses will be presented and discussed.

SESSION 7

177

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European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

BOOKLET PART II: SCIENTIFICALLY-BASED GUIDELINES TO SUPPORT MANAGEMENT STRATEGIES IN ESTUARIES Bergamasco A. 1, L. De Nat2, M. Flindt3 , S. Rolinski4 , G. Umgiesser5 , C. Amos6
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IST, National Research Council, Spianata S. Raineri, 98122 Messina, Italy Thetis SpA, Castello 2737/f, 30122 Venice, Italy Biological Institute, SDU, University of Odense, Campusvej 55, DK-5230, Odense, Denmark Institut fuer Meereskunde, University of Hamburg, Germany ISDGM, Natrional Research Council, S.Polo 1364, 30125 Venice, Italy SOC, University of Southampton, Empress Dock, Southampton, SO143ZH, UK

A CONTRIBUTION FROM THE ELOISE PROJECT: F-ECTS The know-how developed in the context of the project F-ECTS concerning the evaluation of the feed-back mechanisms involving hydrodynamics, phytobenthos communities, nutrient cycling and sediment transport within an estuary has been translated into a Booklet of integrated guidelines to support the selection and assessment of different management strategies in these ecosystems. The aim of Part II is to demonstrate that this evaluation approach can be synthesized in the following “(Monitoring+Modeling)and GIS  Management”. First of all, based on the active role the estuarine phytobenthic communities can have, the main mechanisms and processes responsible for the back- and forward- mediation of the human activities on the estuaries are identified and described. Furthermore Part II deals with (i) the application of empirical modelling from in-situ data and/or GIS analyses to support the production of highly-aggregated information in form of time series or spatial distribution of key parameters and (ii) the demonstration of possible benefits for managers, environment operators and engineers dealing with the set up of strategies or the planning, the design and the comparison of specific management actions in estuarine areas such as wetland restoration, dredging and port operations, fishing activities, transports. In this context scientifically-based criteria to evaluate the “environmental quality” within an estuary in terms of its suitability to sustain the natural ecosystem and the development of human activities are proposed and illustrated for specific case studies.

SESSION 7

178

Oral Presentation

European Land-Ocean Interaction Studies
4th ELOISE Conference 5-7 September 2001, Rende, Italy

A GENERIC DECISION SUPPORT SYSTEM FOR THE EVALUATION OF POLICIES TO REDUCE NITROGEN INPUTS TO WATER Grimvall, A, Forsman, Å. and Wittgren, H.-B.
Department of Mathematics, Linkoping University, Sweden

Decision support systems (DSSs) for the evaluation of environmental policies have two important functions: to predict how the studied policies influence the behaviour of important groups of actors and to predict the impact of a given set of actions on the environment and other sectors. So far, almost all attempts to construct DSSs for environmental management have focused on one subtask, i.e. to assess the environmental impact of a given set of actions. In this article, we describe the generic structure of a DSS that enables a more complete evaluation of regional or national policies to reduce nitrogen inputs to water. In particular, we describe the principles of linking economic models of agricultural production at the farm level to catchment-scale models of the transport and transformation of nitrogen in soil and water. A strict definition of system boundaries for nitrogen fluxes through the agricultural sector and the ambient environment form the basis of the model integration. Thereafter, we show how different modules operating on different temporal and spatial scales can be linked to each other by using generic procedures for upscaling, downscaling, extrapolation and conditional simulation. Finally, we demonstrate how statistical emulators or metamodels can be derived to facilitate simulation of the nitrogen transport from land to water for a representative set of weather conditions and realistic spatial distributions of crops, fertiliser application and other characteristics of the cropping systems. In particular, we show when and how the temporal or spatial resolution of model inputs can be lowered without significantly influencing annual nitrogen fluxes on the scale of catchments.

SESSION 7

179

Oral Presentation


				
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