Transcript Oceanography

Eutrophication 1
Definition and History
Alice Newton
University of Algarve
Research Projects
 LOICZ (Land-Ocean Interaction in the Coastal Zone)
 IMBER (Integrated Marine Biochemistry and Ecosystem
Research)
 GEOHAB (Global Ecology and Oceanography of Harmful Algal
Blooms)
 National Estuarine Assessment, NOAA (USA)
 EU projects http://europa.eu.int/comm/research/eloise/eloise-p.html
 National
INAG/IMAR: Identification of Sensitive Areas and Vulnerable Zones in
Four Portuguese Estuaries
www.inag.pt www.imar.pt
 Regional
MARE (Marine Research on Eutrophication) Programme (funded by the
Swedish Foundation for Strategic Research) http://www.mare.su.se
 European
OAERRE
http://tejo.dcea.fct.unl.pt/oaerre/
http://www.oaerre.napier.ac.uk/
Links
Agriculture
Fertilizer use
Domestic Animal Wastes
Tourism
Atmospheric pollution
Photochemical smog
Acid Rain
Greenhouse effect
Biogeochemical
cycles
Fisheries
Eutrophication
Oxygen
BOD
Hypoxia
Water quality
impairment
Aquaculture
Biodiversity
Phytoplankton
HAB
Macrophytes
Links to Other Topics
 Agriculture
http://www.fertilizer.org/ifa/
http://www.tfi.org/
Fertilizer use
Input of N & P > outputs from crops
 Domestic Animal Wastes
manure production>>use
XS N &P reaches aquatic ecosystem
XS N also volatilized
 Water quality impairment
 Atmospheric pollution
 Photochemical smog (Nitric Oxide, NO)
 Acid Rain (Nitric Acid)
 Greenhouse effect (Nitrous Oxide, N2O)
 Soil and Erosion
 Nitrates leach Ca, Mg & K from soil
 Biodiversity
Biogeochemical cycles:
N, P and C. Redfield ratio. Si
Oxygen in the marine environment,
Primary Production, Respiration, BOD,
Hypoxia
http://192.168.1.102/hypox5.pdf
Phytoplankton and harmful algal
blooms (HAB)
ioc.unesco.org/hab/
Defining Eutrophication
Some etymology…
Eu: Greek prefix “good” and “well”
Troph: Greek “nourishment” “nutrition”
“feeding”
Eutrophic: Positive connotation
Eutrophication: Negative connotation
Definition
Eutrophication: nutrient enrichment
of natural waters
Natural eutrophication in regions of
upwelling: cold, deep, nutrient-rich
waters rise to surface eg Chile
Anthropogenic eutrophication is
result of nutrient pollution of natural
waters eg lakes, rivers, aquifers,
estuaries, bays, coastal waters
Scientific definition of
Eutrophication…the good?
“Stimulation of algal growth by
enrichment of the aquatic environment
with mineral nutrients” (Richardson,
1989)
Natural processes are the agents of
enrichment: includes naturally eutrophic
coastal waters, such as upwelling regions
Courtesy of Gay Mitchelson–Jacob
Variation in the Productivity of the
Oceans
Primary Productivity using global monthly SeaWiFS data of chlorophyll (Nov 77-Oct 99) and
the vertically generalised production model from Behrenfeld & Falkowski (1977)
Atlantic is much nutrient-rich and more
productive than the Mediterranean
Mediterranean Chlorophyll CZCS composite
Courtesy of Gay Mitchelson–Jacob
Upwelling regions are especially productive
such as the coast of Chile
SeaWiFS Chlorophyll, 18 Jan 2000 Chile Courtesy of Gay Mitchelson–Jacob
Coastal
Upwelling
off
W. Africa
Coastal Upwelling
Chlorophyll Concentrations (CZCS), Cape Verde Islands
Courtesy of Gay Mitchelson–Jacob
Management definition of
Eutrophication… the Bad?
Anthropogenic Eutrophication: mankind is the
agent responsible for nutrient enrichment
European Environment Agency definition:
“Enhanced primary production due to excess
supply of nutrients from human activities,
independent of the natural productivity level
for the area in question”
UK EA definition
“The enrichment of waters by inorganic plant
nutrients which results in the stimulation of
an array of symptomatic changes.
These include the increased production of algae
and/or other aquatic plants, affecting the
quality of the water and disturbing the
balance of organisms present within it.
Such changes may be undesirable and interfere
with water uses.”
Nutrients & Eutrophication,
EEA
The main nutrients causing eutrophication
are N in the form of nitrate, nitrite or
ammonium and P in the form of orthophosphate.
 In addition, supply of bioavailable organic
P and N cause eutrophication
 Silicate is essential for diatom growth,
but it is assumed that silicate input is not
significantly influenced by human activity.
Enhanced primary productivity may
exhaust silicate and change the
phytoplankton community from diatoms to
flagellates.
Eutrophication process
UK EA
Early Eutrophication Model
Responses:
Changes in
Nutrient loading
Chlorophyll
Primary Production
System Metabolism
Oxygen
Early conceptual models focused on
direct responses of coastal waters, such
as stimulation of phytoplankton blooms.
Direct
Responses
Nutrient
loading
Filter
Chlorophyll
Primary Production
Macroalgal biomass
Sedimentation of O C
System Metabolism
Phyto. community
Si:N N:P
Oxygen
HAB
Indirect
Responses
Benthic biomass
Pelagic biomass
Vascular plants
Habitat diversity
Water transparency
O C in sediments
Sediment biogeochemistry
Bottom-water oxygen
Seasonal cycles
Mortality
Biodiversity
Contemporary conceptual model
Cloern J.E. 2001
Contemporary conceptual model
Growing awareness of the complexity of the
problem
Attributes of specific bodies of water create
enormous variations in their responses
Cascade of direct and indirect effects
Appropriate management actions to reduce
nutrient inputs can reverse some of the
degradation caused by enrichment.
History of Eutrophication
History of Fertilizer
Historical fertilizer
shortage
18th Century England
“mined”
battlefields and
catacombs
19th Century USA used
bones
from buffalo killing
fields
Guano deposits mined
eg Navassa guano trench
Haber-Bosch Process
 Fritz Haber
(Nobel prize winner)
described chemical
process to produce
NH3 from N2 & CH4
 Carl Bosch
(Nobel prize winner)
perfected commercial
manufacture
Industrial N fixation
 N2 from atmosphere
mixed with CH4 and
heated under pressure
with a metallic catalizer
produces CO2 and NH3
(82%N)
 Mean plant production is
1.5 million kg ammonia
per day
History of Eutrophication
Eutrophication first noticed in lakes
where P is the main problem
Also noticed in rivers
Estuaries: eg Chesapeake bay
Bays and coastal waters affected: eg
Gulf of Mexico
70 % of world population lives in
coastal plains, increasing pressure