Maurizio Ribera d’Alcalà Stazione Zologica Anton Dohrn, Napoli, Italy

Water masses properties, chemical signatures and

biological processes in coastal marine environment

Maurizio Ribera d’Alcalà

Stazione Zologica Anton Dohrn, Napoli, Italy

Stazione Zoologica Anton Dohrn

1872

2007

Napoli of...Maradona

Brief overview

Tuning the language: definitions and basic concepts

Coastal environments: main traits, key processes, benthic vs. pelagic, biogeochemistry vs. ecology

General framework: the COSCAT synthesis

Biogeochemical processes: case studies

Cuba case: nitrogen budget

Filling the gaps: observational requirements and tools

1. Coastal areas: from low-tide mark inland extending seaward, including ecosystems near shore: (barrier islands, mangrove swamps, salt marshes, seagrass beds, coral reefs, etc.)

Definitions and basic concepts


2. The focus is the biotic component of the ecosystem




3. Biota grow, reproduce and die, and all runs on the continuous transformation of inorganic substances into biomolecules and back, based (dominantly) on oxygenic photosynthesis




3. Biota grow, reproduce and die, and all runs on the continuous transformation of inorganic substances into biomolecules and back, based (dominantly) on oxygenic photosynthesis

4. Our jargon includes (with the relative units):a. biomass (chlorophyll, dry weight, abundance, etc.),

nutrients (with the constraint of mass balance)

b. primary producers and consumers

c. new production, export production, trophic regime

d. Biodiversity


• Steep slopes and rapid changes in topography create small, scattered ecosystems

• Small size of ecosystems

• Concentration of population and activities in small areas intensifies stress conditions

• High frequency and variety of natural disasters

• Close coupling of terrestrial, coastal and marine systems results in fast-spreading impacts among systems

Roger-Mark De Souza

Importance for Caribbean

Vicinity to land implies:

• freshwater runoff

Main traits


• freshwater runoff • coastal Ekman transport

Main traits


• freshwater runoff • coastal Ekman transport• significant tidal dynamics

Main traits

Terrestrial runoff:modifies the water budget and the

thermohaline circulationconfers a strong signature (amount and ratios)

to nutrient inputs

Key processes



to nutrient inputs

Key processes

Ekman transport:UpwellingTidal dynamics:strong periodic currents, mixing



to nutrient inputs

Key processes

Ekman transport:UpwellingTidal dynamics:strong periodic currents, mixing

Land driven vs. ocean driven systems

barrier islandsmangrove swampssalt marshesseagrass bedscoral reefs

Benthic vs. pelagic

Seasonal cycle of phytoplanktonRed TidesCrustaceans, Jelly fish, Clupeids

Benthic vs. pelagic

Margalef, 1962

Daily Primary production in the Caribbean Region

Benthic vs. pelagic

Margalef, 1962

Distribution of Sardinella and choral reefs

Focus on fluxes and biomassFunctional groupsAlmost always bottom-up driven

Biogeochemistry vs. ecology (a drastic schematization)

Focus on the biology of speciesInteractions among the speciesEmergent properties neither bottom-up or

top-down

Meybeck et al, 2007

The COSCAT (COastal Segmentation and related CATchment)

Endorheic drainage

Exorheic drainage

The land ocean interface

The mega filters

Meybeck et al, 2007

Enclosed sea

Semi-enclosed sea

Open regional sea

Archipelago coast

Extended platform

Meybeck & Vorosmarty, 2005

Zooming in

The COSCAT synthesis

Meybeck et al. , 2006

Meybeck & Vorosmarty, 2005

Anthropocene: a big change

Meybeck et al., 2007

Major regional seas and other megafilters

Meybeck et al., in press

Catchment area (Ab) over basin area (Ars)


Yearly average water runoff


Average population distribution over the catchment area


Population in the coastal areas over that in the catchment area

• 60 percent of the Caribbean population lives less than 100 kilometers from a coast

• 30 percent of the population is under age 15

• 7 percent is over age 65• All capital cities in insular Caribbean are

on coasts• Coastal areas identified with principal

industrial complexes, trade centers, and resort tourism enclaves

Roger-Mark De Souza

Human pressure in the Caribbean


Nitrogen load increase from pre-industrial to industrial time

Eutophication

Vitousek et al., 1997


Riverine transport vs. input in the wtershed

• Other models make use of statistical rules and fuzzy logics (RIVERSTRAHLER, SOIL/SOILN).

• Less direct measurements are needed

• Lower computational demand allows combined N-P tracking in ecological coupled processes

• Most of N-retention occur when agricultural leach passes through riparian wetlands (Billen & Garnier, 2000)

• But low predictive power for changes in individual sources

Garnier et al (2002)

Forsman et al (2003)

Escaravage, Herman, Carlo Heip: NIOO

River nutrient inputs

• Residence time in upper

aquifer 1-2000 yrs (Kunkel &

Wedland, 1997).

• Fertilizers added last

century will continue to

leach from aquifers to rivers

for decades (Grimval et al.,

2002)

• Significant amounts of

nutrients are directly

brought from groundwater

to the sea (Gregerson, 2003)



Atmospheric input are intermittent• Large deposition of nitrogen may

occur during short periods (de Leeuw et al., 2003)

• Kattegat Strait: events of high deposition increase chlorophyll by 20% (Hasager et al., 2003)

• About 30% of new production off Ireland supported by atmospheric N-inputs in May 1997 (Spokes et al, 2000)

• 38% of summer new production off Creta sustained by P-deposition (Markaki et al., 2003)

de Leeuw et al (2003)

Atmospheric Nutrient Inputs


• Black Sea P, Si benthic regeneration is in the same range as Danube discharge, but intense denitrification occurs (Friedl et al., 1996).

• Intense nutrient regeneration sustains the high productivity in the Black Sea coastal zone (Friedrich et al., 2002)

Friedrich et al (2002)


Fate of nutrients in coastal areas

• Benthic Fe and Ca act as buffer pools that sequester P, not available for primary production (de Wit et al. 2001)

• Increasing nutrient loadings push the system towards reduced states (Wijsman et al, 2002).

• Eventually toxic H2S and Ca/Fe-bound P are released (Heijs et al., 2000)

• Benthic system reaches a new stable state, highly reactive to nutrient enrichments (Heijs et al., 2000)

H2S

Wijsman et al (2002)

Nutrient enrichmentNutrient enrichment

Stable statesStable states



• Empirically calculated denitrification rates f(NO3,O2) are no more accurate when

micro/macro- benthic algae and/or macrofauna are active (Nielsen et al., 2001)

• Without model improvement, nitrogen retention should still been estimated by either mass balance or in situ direct measurements (Nielsen et al., 2001).

• Newly evidenced processes (DNRA, AMMANOX) are alternative pathways for denitrification (Welsh et al., 2001, Dalsgaard & Thamdrup, 2002)

Christensen et al. (1990)

AMMANOXAMMANOX

1.-Denitrification1.-Denitrification

2.-DNRA2.-DNRA

3.-Nitrification3.-Nitrification

Kelso et al. (1997)Kelso et al. (1997)



• Micro-algae efficiently incorporate mineralized nitrogen that is no more available to bacteria for denitrification

• The auto/heterotrophy of the system determines whether it acts as a sink or source of

nutrients.(Risgaard & Petersen, 2003)

DenitrificationDenitrification NitrificationNitrification

NONO33



• Seagrass beds act as N-sink; biomass is eventually buried or exported (Welsh et al, 2000).

• Denitrification is at low rates in seagrass beds but chemistry there is far to be understood (Welsh et al., 2001)

Welsh et al (2000)

DenitrificationDenitrification FixationFixation DenitrificationDenitrification FixationFixation



• Six-fold increase of the non-diatom bloom

(1960/1992) in Black Sea with increased

nitrogen discharge (Humborg et al., 1997).

• Unbalanced nutrient additions (N≫P,Si) to

North Sea ecosystem induce Phaeocystis

colony blooms, not grazed by copepods (Rousseau et al., 2000).

• Field observations (Gasparini, 2000) and

mesocosm experiments (Escaravage & Prins,

2002) suggest efficient grazing on Phaeocystis

cells by ciliates after collapse of the colony

bloom

Rousseau et al (2000)

Escaravage & Prins (2002)


Effect of altered discharge

• Acute eutrophication effects on benthic fauna through habitat alteration are rather well documented (Pearson & Rosenberg, 1978).

• Tracer experiments show that benthic organisms primarily feed on fresh vegetal matter rather than detritus (Herman et al., 2000)

• Macrofauna biomass also show a tight link with benthic primary production (Herman et al., 2000).

Phytoplankton

Detritus

Microphytobenthos



Southern California

Red Tides

Red Tides

Florida

The Redfield ratio: a key issue

Klausmeier et al., 2004

Is the Redfield ratio fixed?

New insights

Riverine transport vs. population


Fertilizers

Cuba nitrogen budget

Baisre, 2006

Atmospheric deposition

Anthropogenic biological N fixation

N import (food)

Total fluxes

Cuba nitrogen budget

Baisre, 2006

Trend of anthrogenic impact

Impact on fisheries (?)

Emirical Orhogonal Functions of chlorophyll a proxy

Mode 1

Mode 2

Remote sensing

Empirical Orthogonal Functions of terrestrial load

Remote sensing

30 X 30 km LEO CPSE

An Integrated Observatory

Integrated observing systems

300km x 300km Began in 2001

Integrated observing systems

ELEMENT ISOTOPE ATOMIC

WEIGHT (amu)

ABUNDANCE (atom %)

ABSOLUTE RATIO

HYDROGEN 1.0079

(Z=l) lH (Protium) 1.007825 99.985

2H (Deuterium) 2.014102 0.015 1.557 10-4

CARBON 12.011(Z=6) 12C 12 98.9

13C 13.00335 1.1 1.122 10-2 NITROGEN 14.0067(Z=7) 14N 14.003074 99.63

15N 15.00109 0.37 3.613 10-3

OXYGEN 15.9994(Z=8) 16O 15.994915 99.76

17O 16.999131 0.04 2.0052 10-3

18O 17.99916 0.2 3.76 10-4

Stable isotopes

Walker et al., 1989

Partitioning of stable isotopes of an element amongst different coexisting phases is called FRACTIONATION and is a MASS and TEMPERATURE dependent process

Fractionation leads to variation in the natural abundance of stable isotopes expressed as differences in ISOTOPE RATIOS, R

ALWAYS: R = HEAVY ISOTOPE/ LIGHT ISOTOPE

THAT IS: R = RARE ISOTOPE / ABUNDANT ISOTOPE

e.g. D/H, 13C/12C, 15N/14N , 18O/16O

Rona Mc Gill, www.gla.ac.uk/centres/surrc/index.html

Fractionation

Bonds involving “light” isotopes break more readily than those involving “heavy” isotopes

Rate determining step which includes breaking of bond dictates isotopic fractionation of entire process

Typical of processes which are unidirectional and irreversible

Non-equilibrium isotope fractionation – Kinetic effect


Equilibrium isotope fractionation = isotope exchangefor 2 or more phases with a common element, the atomic ratio (R) of heavy to light isotopes differs among the equilibrated phases

Equilibrium fractionations are largest for elements that have low atomic weights and form covalent bonds (vibrational frequency depends on mass unlike ionic bonds charge)

The difference of one or more neutrons creates a relatively large relative difference in mass between the isotopes

Equilibrium isotope fractionation


Carbon cycle

White, 2001

13C of Dissolved Inorganic Carbon in the ocean

Kroopnik, 1985

Phosphate and 13C of DIC in the Pacific Ocean.After Broecker and Peng, 1982

• Present models deserve conceptual refinements:

• dynamic coupling with biological processes

• incorporation of major macronutrient (N,P,Si) and organic matter.

• merging of deterministic and statistic approaches

• incorporation of a groundwater module

Garnier et al (2002)



• A generic size structured food web

model captured the patterns for

scaled ecosystem experiments

performed throughout Europa.

• Efficiency of the top-down control

determines when nutrient

accumulate in vegetal biomass or

reach higher trophic levels.

(Olsen et al., 2001)



• Much knowledge has been

gathered on benthic nutrient

fluxes that cannot be

analytically solved with a single

set of chemical equations

• Current progresses at the

frontline of process modeling

are developing the tools that

will allow this integrative step (Meysman et al., 2003a,b)Overview of different object types

building blocks within the MEDIA objectorientated modeling environment(Meysman et al., 2003a).



► The most complex models may not always

be the most suitable; lower boundary

levels has to be considered regarding the

question to be addressed (Soetaert et al.,

2000).

► Simple LOICZ-type box models are well

suited for large scale (e.g. ocean margin)

nutrient budgets (Durrieu de Madron, 2003).

► When processes within the coastal

systems are addressed, more complex

models may be required (Soetaert et al.,

2000).Scheme for a fully coupled model

(Soetaert et al., 2000)


Integrating modeling skills

Modelling atmospheric inputs• Remarkable spatial

resolution with 17 x 17 km boxes

• 30% of nitrogen input to sea comes from the air

• Wet deposition represents 81% of N-deposition

• 38% from agriculture, 72% from combustion sources

Hertel et al (2002)



Modelling atmospheric inputs

• Assessment of nutrient deposition

requires a fine grided model

dynamically coupled with a

meteorological model.

• Efforts to be deployed Europe-wide

instead of focus on North Sea and

NW Mediterranean Sea.

• Both N and P-deposition to be

addressed by monitoring efforts

de Leeuw et al (2003)



Maurizio Ribera d’Alcalà Stazione Zologica Anton Dohrn, Napoli, Italy

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