Curso de Lagunas CosterasAlice Newton

Universidad de Algarve, Portugal

Universidad EAFIT, Abril 8-23, 2008

22 Abril

~Cambio global y las lagunas costeras.

~Escenarios futuros

Cambio Global y las lagunas costeras

Coastal zones and lagoons play a key role in Earth System functioning

Provide a significant contribution to the life support systems of most societies.

Goods and services derived from coastal systems depend strongly on multiple trans-boundary interactions with the land, atmosphere, open ocean and sea bottom.

Human habitation, food production, growing tourism and transportation accelerate the exploitation of the coastal landscape and resources.

Coastal lagoons and Earth System Science

Global change and coastal lagoons

~ Changes in ecosystem function and biodiversity

~ Changes in biogeochemical cycles~ Changes in sea level and morphological

modifications~ Changes in sediment supply and erosion~ Changes in population, urbanization and

tourism~ Changes in use of lagoons: salt and fisheries,

aquaculture~ Changes in economy and ecosystem services

Coastal lagoons are fragile due to direct water draining form highly inhabited areas, their shallowness and low water volume to surface ratio.

As a consequence there is a high probability that among marine ecosystems coastal lagoons will be the first to react to consequences of changes in climatic trends

(Esenreich, 2005).

Climate Changeand the

European Water Dimension

A Report to the European Water Directors2005

Lagoons are

sentinel systems

Monitoring and data sets

~ Long time-series of data

~ Historical data sets

~ Rare but valuable

~ Useful in hindcast scenarios

~ Heterogeneous meta-data remains problem

~ Accessibility issues

Ringkøbing Fjord,

North Sea, Dk

16361636

Ringkøbing Fjord,

North Sea, Dk

17681768

Nymindegab, Dk

Vulnerability and risk

~sea-level change

~coastal erosion

~storms~tsunamis

Vulnerability maps

Vulnerable and valuable ecosystems

Lagoons are valuable ecosystems, provide valuable ecosystem services and support valuable activities such as tourism, aquaculture and fisheries.

Lagoons throughout the latitudes are subject to multiple pressures

Lagoons are very vulnerable to global, natural and societal changes

In particular:~ Erosion-deposition~ Sea-level change~ Changes in the water and

biogeochemical cycles~ Human settlement and exploitation

of natural resources

Coastal lagoons are vulnerable systems

•High population density (>60/km2) •High cropland use (>10%)

Global typology (polar regions cropped)

Potential Vulnerability Level (PVL)

Units Low Moderate High

Very High

Score 3 2 1 0

Water Residence Time Days <1 1-7 7-15 >15

Net Ecosystem Metabolism mol m-2y-1 >5 5-0 0-(-5) < -5

Granulometry - Sand Sand-silt Silt-clay clay

Sedimentary Organic Matter

% dw < 1 1-5 5-10 >10

Sedimentary C:N ratio - >20 10-20 5-10 <5

Sedimentary Reactive Iron µmol cm-3 >200 100-200 50-100 <50

Sedimentary AVS µmol cm-3 <50 50-100 100-150 >150

Sedimentary carbonates % dw >40 20-40 5-20 <5

Venice lagoon is the best known case study of sea level rise

Flooding of Piazza San Marco

~ Sea level trend at Trieste (open) and Venice (green), 1896-1996. Source: Carbognin L, CNR, Venice, Italy, and Rafael Bras, MIT

Annual distribution of exceptional high water events, 1923-1996.

Source: Centre for tidal forecasting of the Venice Municipality and Rafael Bras, MIT

Flooding in St. Mark’s Piazza

Rising sea level has led to increased flooding of Venice

Acqua Alta

Acqua Alta doesn’t

deter tourists

Brenta CanalBrenta Canal

Brenta RiverBrenta River

VeniceVenice

Water diversion reduced sediment delivery to Venice Lagoon

Venice circa 1500 Source: Consorzio Venezia Nuova

Management responsesSource: Chiozzotto and Drusiani, IWA Conference 2002

A massive engineering

project has been initiated for storm surge

protection

Escenarios futuros

~ Why are coastal lagoons an “issue” for the 21st C?

~ What is the prognosis for coastal lagoons?

~ What have we learned about coastal lagoons?

~ What do we still need to work on?

Types of Scenarios

~ Global change: eg rate of sea-level rise, storm frequency, erosion/deposition rates

~ Futures: business as usual, industrial development, green “eco-scenario”

~ Modeling: increase pig farming, build sewage treatment plant, grant aquaculture concessions

What is the scenario?

Santa Marta:

~ Industrial and port development “full speed ahead”

~ Tourist and golf resorts

~ Aquaculture and mineral extraction

~ Eco-tourism paradise, no development

Scenarios

Cartagena?

“Your” lagoon

Who are the actors?

~ Scientists?

~ Stakeholders?

~ Decision makers and managers?

Stakeholders

Decision makers

Scientists

21stC Prognosis for coastal lagoons?~ Coastal lagoons are ephemeral, dynamic

systems on a geological time-scale Consequences of climate change and sea-level rise? ~ We will loose some coastal lagoons, some very

soon, e.g. Chesil fleet in the UK~ New coastal lagoons will form in flooded coastal

plains~ Furthermore, what are the consequences of

changes in the biogeochemical cycles ?~ Increased urbanization of the coastal zone?

Scenarios (consider main economical activities and DPSIR scheme):• Extension of clam farming areas• Simulation with different initial clam densities• Simulation with different seeding levels• Simulation with and without macroalgae • Natural variability/Climatic changes (wet/normal/dry years)• Human activities in the watershed (variation of nutrient loads: lower/normal/higher )

Scenarios developed together with the regional authorities eg Sacca di Goro, Ferrara Province, Italy

Scenario 1 : Areas of priority - identification of sub-areas of the basin where the highest effect of management intervention is obtained in terms of N-load reduction to coastal waters.

Scenario 2: A targeted 35% reduction in nitrate loads by means of implementing the national program, Environmentally Sound Agricultural Production'( MVJ) (7000 ha), catch crops (5000 ha), reduced discharge from pump drained areas, restored wetlands (4000 ha).

Scenario 3: A targeted 50 % reduction in nitrate loads by means of all scenario 2 elements and an additional reduction in animal stock (29.000 animal units) in selected areas of the basin.

Examples of management scenarios Ringkøbing Fjord, Dk

From science to management and back to science

~ Science, i.e. ecological status, biogeochemical cycles and fluxes, climate change, etc.

~ Science for management, e.g. assessing environmental flows, sustainable yields, etc.

~ Science of management, e.g. modeling human impacts and land uses, resource optimisation

~ Management based on science, e.g. wetland restoration, lagoon sustainability,

~ Managing competing demands of society – policy and politics

Goal: integrating science in management

The sustainability challenge

GEOMORPHIC SUSTAINABILTY(relative sea level rise, sediment deficit)

ECOLOGICAL SUSTAINABILITY(pollution, fragmentation, global warming)

SOCIOECONOMIC SUSTAINABILITY(overexploitation, land uses, policy)

Goal : integrating the three levels of sustainability