COASTAL ZONE IMPACTS ON GLOBAL BIOGEOCHEMISTRY:
TOPIC # 1: HOW DO DIFFERENT COASTAL ZONES IMPACT THE CARBON CYCLE?
CONTRIBUTED BY: I. FALOONA, T. LUEKER, S. NANDI, R. SHIPE, D. VARELA, L.VER
General Information
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Identification of importance of coastal zones by two main carbon cycle documents:
North American Carbon Plan (NACP) and the Ocean Carbon & Climate
Change (OCCC).
Ship-based studies in the East China Sea [Tsunogai et al., 1999] and off the West
Coast of Europe [Frankignoulle et al., 2001] have suggested that the coastal ocean
plays a significant role in the global carbon cycle (Frankignoulle et al. estimate the
European coastal sink to be almost half as large as that proposed for the open North
Atlantic).
1. Nitrogen cycle
Riverine inputs are on par with wet deposition & in-situ fixation
Benthic denitrification in CZ is dominant removal of bioavailable N
There is a tight coupling between the cycles of C and N (and Si) during massive
blooms and export events.
2. Other nutrient cycles
S
DIC
P
Fe: Synoptic scale transport to and fertilization of open ocean
Si: Under eutrophic conditions, the coastal phytoplankton community
is dominated by diatoms. These unicellular protists require Si for
growth (C:Si ~ 106:16)
3. Physical forcing/hydrological cycle
Coastal upwelling, synoptic semi permanent H pressure, Ekman pumping
Boundary currents (great distinction between Eastern/Western) &
corresponding eddy transport processes
Influence of large-scale climate oscillations such as ENSO, NAO, etc.
Increase in stratification of coastal waters thought to affect nutrient abundance
and supply to mixed layer (in Gulf of Alaska study)
4. Important regions
Upwelling regions (N. California Coast, and similar regions in S. Pacific,
S. Atlantic): responsible for ~50% of world’s fish catch
Deepwater delivers large pCO2 (source) as well as nutrients which
instigate large biological blooms (sinks)
Main riverine discharge regions (mostly NH: Amazon, Orinoco, Congo,
Yangtse, etc.)
Transition region between pelagic and coastal environments (e.g., utilization of
NO3 by small autotrophic flagellates vs. diatoms)
5. Methods for constraining
Coastal zone color scanner (for NPP)
Coastal CO2 flux monitoring network
In-situ monitoring experiments such as the NEPTUNE and VENUS projects on
the coastal NE Pacific
Low altitude airborne spectral methods – optimization of satellites
(MODIS, SeaWiFS) for high turbidity of CZs
Atmospheric monitoring of other trace gases (O2, N2O, CO) at coastal time
series stations
Long-term monitoring of C sequestration needs to work towards constraining
lateral advection
6. Uncertainty / big questions
Upwelling CO2 rich deepwater vs. biological drawdown – who wins?
Pronounced heterogeneity of biological response to distribution of
chemical properties (nutrients) – need for better food web characterization
How do the controls on productivity/sequestration coupling (see (7)) vary
geographically, seasonally, and climatically?
Sensitivity to large scale climate oscillations
Strive for sufficient understanding of these processes to allow for
intentional climate manipulation
7. Sedimentation / carbon sequestration rate
14-30% of oceanic NPP (~103 Pg C y-1) concentrated in CZs
Estimates as large as 50% of total bio pump is “continental shelf pump”
To what extent do nutrient supply and offshore eddy transport control the C
sedimentation rates? More generally, what are the physical, chemical, and
biological controls on the productivity/sequestration coupling?
8. Upwelling areas and air-sea fluxes
Possibility of differing air-sea exchange parameters due to: presence of
surfactants, shelf induced turbulent transport, limited fetch, etc.
[Also see (3) & (4) above]
COASTAL ZONE IMPACTS ON GLOBAL BIOGEOCHEMISTRY:
TOPIC # 2: HOW DO COASTAL ZONES IMPACT ATMOSPHERIC CHEMISTRY, INCLUDING
AEROSOLS?
CONTRIBUTED BY: CHRISTINE WIEDINMYER, ADELE CHUCK, IAN FALOONA, TIM LUEKER, MONICA
MADRONICH, KATHARINE MOORE, CINDY NEVISON, MARK POTOSNAK, ROB RHEW, CRAIG
STROUD, JOHN WHITE
General Information
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AEROSOLS
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Nit
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Sea
-salt
TRACE
GASES
Hal
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Increased
productivi
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Varied
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Breaking
waves
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CCN
Ozone
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Green
house
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N2O, CH4
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Halocarbo
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CH3I,
CHBr3
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Sulphur
compound
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DMS,
H2S, COS
DOM
Anoxic
zones
• Eutrophi
#2. How do coastal zones impact
cation
on atmospheric chemistry?• Harmful
algal
blooms
A. Chuck
Figure 1: A general schematic of the atmosphere-coastal interactions of chemical trace
gases.
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Coastal ecosystems are characterized by higher primary productivity than open ocean
systems.
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Ocean-atmosphere interactions within coastal zones reflect a transition from a relatively
contaminated continental land mass to a less contaminated marine air mass
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Coastal seas are dominant marine sources of some trace gases globally e.g. nitrous oxide,
carbonyl sulphide, methane and important production sites for almost all trace gases.
1. Hydrocarbons
a. Macroalgae (seaweeds) have been shown to produce a variety of halogenated
compounds, isoprene, and other NMHCs.
Hydrocarbons & Aerosols
 The “Sea Surface Microlayer” (SSM) is often aerosolized or may coat/be associated
with your regular sea-salt aerosol.

Some of the organic compounds in the aerosol are bacteria or bacteria products.
Functionalities include lipids, carbohydrates, but this is very poorly characterized.
2. Sulfur Compounds
a. Coastal phytoplankton species such as Phaeocystis are important producers of DMS,
although DMS production rates in coastal waters are not particularly high compared to
open ocean areas.
b. Coastal salt marshes have very high sulfur content in their soils, which has two major
effects in terms of trace gas exchange:
a. First, they provide the substrate for the production of sulfur-containing trace
gases, such as H2S, COS, MeSH, and DMS.
b. Second, high sulfate levels inhibit methanogenesis, meaning that coastal marshes
produce very little methane relative to freshwater wetlands
c. H2S and other reduced-S and organo-S species may be present in the gas-phase?
Sulfur Compounds and Aerosols
d. DMS oxidation produces SO2, which ultimately can produce particles. (Probably very
important for new particle production).
e. DMS flux measurements in ocean regions, and the DMS-CCN-cloud studies. (Studies
have been performed to link DMS emissions to CCN production and cloud properties).
References?
3. CO
a. CO is generated in the ocean by photochemical degradation of CDOM (colored
dissolved organic matter) and its main loss is microbial consumption. Only about
15% of this cycling is vented to the atmosphere, where it is believed to represent a
mere 2% of the global atmospheric CO budget [Zafiriou et al., 2003].
b. Very few measurements of marine CO fluxes exist in coastal regions outside
of some high latitude port cities. CO production from wetlands alone may
be
as large as 300-400 Tg C/yr [Valentine and Zepp, 1993] which suggest considerable
potential for elevated CO emissions in estuaries and coastal waters.
4. Nitrogen compounds
a. There is substantial evidence for organo-N being important (gas- and aerosol-phases) in
coastal regions, but these compounds are very poorly characterized.
b. Nitrates may play important roles in estuaries/coastal regions as run-off from fertilizers.
Nitrates in aerosol may be important in perturbed coastal regions.
c. Coastal upwelling regions are important sources of nitrous oxide (N2O). This is true for
two primary reasons. First, coastal regions have high rates of microbial N2O production
as a consequence of their high productivity. Second, upwelling provides an effective
pathway for ventilating N2O, which is produced primarily in subsurface waters, to the
atmosphere. Anthropogenic nitrogen inputs to coastal areas can lead to large
enhancements in coastal N2O emissions. Although N2O is chemically inert in the
troposphere, it is a radiatively active greenhouse gas and also provides the primary
stratospheric source of NOx, an important regulator of ozone.
5. Halogenated Compounds
a. Very high emission rates of methyl halides have been observed in coastal terrestrial
ecosystems.
b. Coastal salt marshes emit methyl halides at high rates, depending on plant species and
environmental parameters.
c. Tropical coastal lands also emit methyl halides, also apparently from vegetation.
d. These coastal ecosystems are regions of high primary productivity and high halide
availability.
e. Macroalgae are known sources of volatile organo-bromine and organo-iodine
compounds.
f. Bromoform is the most abundant form of biogenic reactive organic bromine and the
highest concentrations of bromoform are invariably found in coastal waters.
g. Possibly 70% of world’s bromoform produced by macroalgae (Carpenter and Liss 2000).
h. Macroalgae area also sources of a variety of iodinated compounds e.g. CH2I2, methyl
iodide. Current understanding is that this source is not globally significant but impact on
local atmospheric composition and chemistry could be greater. E.g. “particle bursts”
have been observed in some coastal areas. There is evidence to show that condensable
iodine vapours (CIVs) formed from photolysis of CH2I2 produced by macroalgae is a
viable mechanism for explaining this.
i. Figure 1 (L. Carpenter) shows the (almost textbook!) relationship between tidal height,
solar radiation and IO production. The relationship between CCN concentration and tidal
height has also been shown in the field during the PARFORCE project.
j. Halogen cycling in coastal environments can be substantial and important in terms of
ozone and other oxidant cycling
k. Some observational evidence that Cl-radical chemistry in polluted air over the coastal
ocean can lead to net O3 production (Texas studies- Tanaka et al., 2003)
Iodine
Chemistry in
the MBL
I
O
O3
CH2I2
CH2IB
r
CH3I,
h
v
I
h
v
Ozone
Depletion
Inorgani
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Iodine
eg
OIO,
HOI
IONO2,
INO2,
HI, IX
I2
New Particle
Production;
Climate
Impact
Aeros
ol
Transpo
rt
to
Contine
nts
J. Plane
Figure 3: Iodine chemistry in coastal regions.
Halogenated compounds and aerosols
o Organic-Iodide compounds (methylated iodines) have been associated with new particle
production in tidal areas. (O’Dowd et al., 1999, 1998).
o Interaction with NOx will release HCl from aerosol and this has the potential to end up as
radical-Cl, which will play a role as an oxidant in coastal regions.
o Br may also be released as a radical (not in as large of quantities as Cl, of course).
6. Feedbacks
a. Ocean-derived CCN impacting productivity, soluble iron amounts being impacted by
sulfur or organic acid emissions from oceans.
7. Methods for constraining
a. Need better and continuous observations for several years at one (or multiple) location
locations.
b. Need to get estimates of surface area, productivity, species abundance.
c. Better/more flux measurements?
8. Uncertainty/big questions
a. What are the physical and biological constraints on trace gas exchange in the salt marsh?
b. What is the effect of short-lived halogenated compounds on atmospheric
chemistry/aerosol formation?
c. What are the impacts of increased nutrients on coastal ecosystem dynamics and the
emission of climatically active trace gases?
d. What are the mechanisms producing the ultra-fine particle bursts?
e. Harmful algal blooms – trace gas production from these species unknown
f. What is the size distribution of aerosol produced by wave-breaking? (important for CCN
production and for reaction sites/composition).
g. As with many things, the organic composition of the aerosol produced (and what they
evolve into) are not well-known.
h. In addition to the gas emissions from the microorganisms, what role is played by their
physical bodies/fragments?
i. Kelp forests are large producers of methyl iodide, but how much of it reaches the
atmosphere?
COASTAL ZONE IMPACTS ON GLOBAL BIOGEOCHEMISTRY:
TOPIC # 3: WHAT ASPECTS OF COASTAL ECOSYSTEMS ARE SIGNIFICANT GLOBALLY?
CONTRIBUTED BY: G.-K. PLATTNER, J. KLEYPAS, C. NEVISON, R. RHEW, A. SUBRAMANIAM
1. How much do coastal zones matter for global atmospheric carbon dioxide?
a. Overview
Whether on a global scale continental margins are currently a net sink or source of atmospheric
CO2 is still cause for debate. Conventional wisdom suggests that continental margins are a net
source of CO2 to the atmosphere, mainly driven by the large riverine inputs of terrestrial carbon
and subsequent local remineralization. However, recent estimates based on regional studies point
to a net CO2 air-to-sea flux in the continental ocean margins at present times, with globally
averaged sink values ranging from 0.2 Pg C yr^-1 to as much as 1 Pg C yr^-1. In a recent
synthesis paper, Chen (2004) estimates that the coastal margins constitute a net CO2 sink of 0.36
Pg C yr^-1 to the atmosphere based on mass balance calculations, as well as direct pCO2
measurements. This flux is a composite over many estuaries, coastal waters, and intensive
upwelling areas, typically supersaturated with respect to CO2 and most open shelf areas, which
are probably undersaturated. According to this synthesis the net CO2 uptake in the coastal zones
is primarily driven by cross-shelf transport from nutrient-rich subsurface waters offshore.
Overall, this coastal CO2 flux is a significant sink component in the global carbon cycle, given
that the global ocean is believed to absorb nearly 2 Pg C yr^-1 of CO2 at present.
b. CaCO3
Calcium carbonate plays a significant role in the global carbon cycle, in that it acts as a
biogeochemical carbon buffer between atmosphere, ocean, and the geosphere. Marine calcium
carbonate production, through the chemical reaction Ca2+ + 2HCO3-  2CaCO3 + 2H+, shifts the
carbon system equilibrium in seawater toward more acidic conditions, which results in a release
of CO2 to the atmosphere (for every mole of CaCO3 precipitated, approximately 0.6 moles of
CO2 are released). Dissolution of CaCO3 works in reverse to take up CO2. CaCO3 production
in the open ocean is considerably greater than on the continental shelves, but most of this
production dissolves before it reaches the ocean sediments. A much greater proportion of
CaCO3 production on continental shelves is preserved within the shallow shelf sediments.
Changes in shallow shelf CaCO3 production almost certainly contributed to the glacialinterglacial changes in atmospheric CO2 (Archer et al. 2000, Ridgwell et al. 2003) but by how
much is uncertain. Flooding of continental shelves during post-glacial sea level rise greatly
increased available area for CaCO3 production, and much of that production was locked away in
shelf sediments. This potential link between fluctuations in atmospheric CO2 concentration and
shallow shelf CaCO3 preservation is termed the "coral reef hypothesis" because coral reefs are
thought to be the main player in these CaCO3 changes (Berger 1982, Opdyke and Walker 1992,
Kleypas 1997). Today, the estimated release of CO2 to the atmosphere by shallow water CaCO3
production is immeasurable against the background of CO2 released by fossil fuel combustion.
However, it is likely that increases in atmospheric CO2, and associated changes in seawater
chemistry are driving net CaCO3 production down, both due to a reduction in biological CaCO3
production (considerable evidence shows that many organisms slow down calcification rates as
more CO2 is driven into seawater), and an increase in geochemical CaCO3 dissolution (although
this will not be effective in reducing atmospheric CO2; see Andersson et al. 2003). There are
other competing variables, such as changes in temperature, light penetration, or nutrient inputs,
that can also affect CaCO3 production and preservation.
c. Past and future role of coastal zones? Role of anthropogenic perturbation?
d. Carbon transport through the system?
2. How large is the impact on atmospheric chemistry and aerosols at different spatial scales?
a. Global significance of coastal areas to N2O emissions:
Coastal areas are believed to be a large source of the atmospheric greenhouse gas nitrous oxide
(N2O). Recent studies have estimated that N2O emissions from coastal areas may account for 545% of the global oceanic N2O source, which in turn contributes ~30% of the total (natural +
anthropogenic) N2O source. Studies that consider anthropogenic N inputs tend to estimate the
highest coastal N2O emissions. One recent study from the heavily polluted southwestern Indian
continental shelf alone estimated N2O emissions equivalent to 10% of the global oceanic total.
b. Global significance of coastal areas to CH4 & DMS:
Recent estimates indicate that the the coastal oceans are a net source of CH4 (0.1x10^12 mol
CH4 yr^-1), and DMS (0.07x10^12 mol DMS yr^-1) to the atmosphere (Chen, 2004). For CH4
shelf sediments are believed to be the principal source, whereas DMS originates mainly from
biological production in the water column. While both these net fluxes are small compared to
e.g. the large CO2 fluxes, they are important on a global scale given the effect of CH4 and DMS
on the radiative balance of the earth.
c. Other constituents?
3. Coastal salt marsh and mangrove swamps
4. River discharge
a. Role of rivers in general
Rivers are the major conduits for the transport of water, salt, organic matter, and mineral matter
from land to the ocean. A significant fraction of the anthropogenic CO2 on land is ultimately
transported to the ocean by rivers. Terrestrially derived macronutrient input to the ocean (N, P,
Si) is also largely controlled by river system processes and these have been impacted by human
activity. Major rivers play a disproportionately important role in this process with the world's 10
largest rivers transporting 40% of all the freshwater and particulate materials entering the ocean.
The Amazon River alone contributes about 20% of the freshwater input into the oceans and
hence while these processes have a global impact, they are not "simply scalable" for
representation in global models. Up to 80% of global carbon burial occurs in river dominated
ocean margins.
b. Export of carbon in rivers to coastal areas
Export of dissolved inorganic and organic carbon in rivers leads to emission of ~ 0.5 Gtons of
CO2-C from receiving coastal waters. These emissions represent a natural cycle of CO2 fixation
on land and subsequent return to the atmosphere via the ocean. The emissions are globally
significant with respect to current efforts to quantify oceanic uptake of anthropogenic CO2
(currently estimated at ~2 Gtons CO2-C/yr) and should be accounted for when using the net
oceanic CO2 flux estimated from surface delta-pCO2 climatologies to estimate anthropogenic
CO2 uptake.
COASTAL ZONE IMPACTS ON GLOBAL BIOGEOCHEMISTRY:
TOPIC # 4: CAN COASTAL ECOSYSTEMS BE REPRESENTED IN GLOBAL MODELS?
CONTRIBUTED BY: C. NEVISON, K. LINDSAY, G. MCKINLEY, G.-K. PLATTNER, R. SEIFERT
1. Prognostic Numerical Models
a. Current representation of coastal regions in global ocean models
Current global ocean biogeochemical models do not explicitly resolve coastal processes. Global
impacts of specific coastal processes are neglected. In coastal zones, the same biogeochemical
parameterizations as used for open-ocean are applied. Resolution of global models is typically 1º
to 4º, with some models achieving up to 1/3º in the tropics, and thus coastal topography is poorly
resolved. Global ocean modelers do not consider results from coastal zones to be useful and do
not evaluate these results.
Biogeochemical processes in global models are parameterized to best fit open ocean
observations. Remineralization of the particle flux is instantaneous in the bottom layer, such that
no sediment burial occurs either in the open ocean or in the coastal zones. There is no explicit
sediment model. Dilution of tracers by freshwater input from rivers is included, but inputs of
nitrogen, DIC, or other tracers from land are not considered. In MOM4 – Phytoplantkton (J.
Dunne), an explicit iron source from the bottom sediments, proportional to the particle flux
reaching this layer, is included at all grid points. A recent modification to this model is to also
include a Fe source from locations with a vertical land / ocean boundary. Future directions under
current consideration with MOM4 are to include land nitrogen inputs via coupling with the
GFDL land model.
b. Nested regional models of coastal upwelling
One possible way to better resolve coastal oceans in global ocean biogeochemical models is to
use embedded gridding, allowing the model resolution to be increased in specified regions of
interest. An example of such a model is the Regional Ocean Modeling System (ROMS),
developed and used at UCLA, which is currently applied e.g. to the U.S. West Coast with a
focus on the California upwelling system and to the whole Pacific. Simulations with ROMS can
be performed in multi-level setups, ranging from eddy-permitting to eddy-resolving resolutions.
A standard setup for the U.S. West Coast for example is to run the whole domain on a 15 km
grid (level 0), the central California upwelling region on a 5 km grid (level 1), and, for local
studies, the Monterey Bay area on a 1.5 km grid (level 2). This allows the model to encompass
both the energetic eddy
variability and coastal topography within domains covering a wide range of distinct physical
environments and ecological or biogeographical regimes, while still being fairly computationally
efficient. However, spanning a wide range of ecological regimes requires rather complex
representations of ecosystems in order to realistically reproduce observations from different
domains. A "simple" NPZD-model has been used successfully for the diatom-dominated central
California upwelling region, but is insufficient further offshore towards the subtropical, nano- to
picoplankton-dominated oligotrophic gyre. Therefore, a more complex biogeochemical model is
used for the Pacific model.
c. Regional models of other (non-upwelling) coastal areas, e.g., U.S. east coast salt marsh
2. Diagnostic Models
Since current global prognostic models do not explicitly resolve coastal processes, and
since configuring regional prognostic models to all coastal areas may be impractical, it may be
useful in some cases to develop simpler diagnostic models to address coastal research issues.
For example, Nevison et al., [2004] recently developed a global model of the coastal upwelling
emissions of nitrous oxide, a greenhouse gas produced in subsurface waters in association with
O2 consumption by microbial respiration. The model was based on satellite winds, their
orientation to the coastline, and a dissolved oxygen climatology. The model was useful in
identifying regions of regions of high subsurface N2O production that overlapped with strong
and/or frequent coastal upwelling events that ventilated the N2O to the atmosphere. We did not
apply the model to non-upwelling coastal regions, although other global models of coastal N2O
emissions, based on estimates of river N export, have not distinguished between upwelling and
other coastal ecosytems. For species such as CO, hydrocarbons and sulfur compounds, which
are produced in surface waters, the distinction between different types of coastal systems may
not be as important; it may be possible to develop simple global models of the emissions of
these species based, e.g., on satellite chlorophyll data and solar insolation.
3. Representation needs
a. How many different types of coastal zones need representation (temperature / topography /
phytoplankton types)?
b. What processes do we need to capture / understand how well?
c. Can these processes be parameterized / resolved in models?
COASTAL ZONE IMPACTS ON GLOBAL BIOGEOCHEMISTRY:
TOPIC # 5: HOW DO HUMANS IMPACT COASTAL ZONE BIOGEOCHEMISTRY AND WHAT ARE THE
ECONOMIC IMPACTS OF THESE CHANGES?
CONTRIBUTED BY: M. POTOSNAK, R. RHEW, R. SIEFERT, J. WHITE
1. What are the main ways that humans impact coastal biogeochemistry?
a. Rising sea level due to global temperature increase, which threatens coastal ecosystems.
b. Sediment loading of rivers.
c. Nutrient loading of rivers (dead zones).
d. Changing the hydrological regimes of rivers flowing into coastal zones. Examples
include the Colorado River (no flow to ocean) and the Everglades (drastic modification
of the sheet flow).
e. Introduction of invasive species (may be more relevant for ecology rather than
biogeochemistry, though). On the fringe, I read an article in EOS in 1998 (vol 79, #35)
about an exotic species of rodent called nutria that is eating away the Blackwater
National Wildlife Refuge off the Chesapeake Bay.
f. Over fishing (again, more of an ecosystem impact).
g. From the Pew Report4:
i. Nonpoint source pollution: oil leaks, nitrogen,
ii. Points source pollution: feedlots, cruise ships
iii. Invasive species
iv. Aquaculture: particularly salmon farms
v. Climate change: air temp, coral re
2. What are the economic impacts of these changes? (e.g. fisheries?)
3. How has the areal extent of terrestrial coastal ecosystems changed?
a. "Saltmarshes and Mangrove swamps are of tremendous importance to the U.S. Fish
and Shellfish industries. Despite their incredible economic importance, until recently
coastal wetlands were perceived primarily as potential development sites. The earliest
estimate of total coastal zone wetlands comes from the 1922 Yearbook of
Agriculture. At that time the U.S. possessed an estimated 7,363,000 acres of tidal
marshes. A similar survey conducted in 1954 estimated that 5,290,000 acres of tidal
marshes were left (Teal and Teal, 1968) - a staggering loss of fully 25% in just 32
years. Today, approximately half of all coastal wetlands in the lower 48 states have
been destroyed. According to the National Marine Fisheries Service (1983), annual
fishery losses due to estuarine marsh habitat loss are estimated at $208 million."2
b. Coastal wetlands include salt marsh/mangrove, fresh marsh, tidal flats, and swamp.
For the purposes of the following discussion, coastal wetlands refer to salt marshes
and mangroves only. Terrestrial coastal ecosystems (salt marshes and mangroves)
contain among the most productive plant communities in the world and serve
numerous ecological and economic functions, such as fish nurseries, water
purification, and bird habitat. However, these ecosystems are also among the most
pressured, as mangrove swamps have been destroyed for use as shrimp farms, and
salt marshes have been destroyed for urban development.
c. In a 1986 (NOAA) Inventory by Alexander, Broutman, and Field, the amount of
coastal salt marshes in the U.S. was 4,446,300 acres, but this estimate was based on
inventories that ranged from the 1950s to the 1980s.
4. Land use change and movement of terrigenous material
References:
1
http://yosemite.epa.gov/oar/globalwarming.nsf/content/ImpactsCoastalZones.html
2
http://agen521.www.ecn.purdue.edu/AGEN521/epadir/wetlands/estuarine_uscz.html
3
http://oceancommission.gov/documents/prelimreport/welcome.html
4
http://www.pewoceans.org/oceans/index.asp