sandy beach ecosystems and climate variabilitysandy beaches provide irreplaceable ecosystem services...
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Sandy beach ecosystems and climate variability Omar Defeo, Leonardo Ortega, Eleonora Celentano, Diego Lercari, Gastón Martínez
• World’s coastlines total almost 106 km
• Sandy beaches dominate open coastlines
• Accreting beaches are the exception (<10%)
• > 80 % are experiencing some erosion
Sandy beaches
tides waves sand
Sandy beaches: main physical factors
1
Weeks
Months
Years
Decades
Centuries
Tim
e
Space (km)10 100 1000
Climate changeand sea-level rise
Beach mining
Exploitation
Coastal engineeringand urban development
Pollution, nourishmentand grooming
Recreation and ORVs
Sandy beaches provide irreplaceable ecosystem services to society
Environment and biota are being threatened by several drivers acting at multiple temporal and spatial scales
Severely under-represented in climate change ecology
Sandy beach threats
Do sandy beaches respond to climate change in ways that are consistent with expectations of hypotheses from general climate-change ecology?
Defeo et al 2009, 2013, Schoeman et al 2014
• Beaches are caught between rising sea and expanding human activity
• Retreat is not possible in most cases because of urban development
• Beach and dunes reduced/lost
Sea level rise
COASTExpanding population Coastal squeeze
The physical environment: coastal squeeze
Coastal squeeze + erosion: negative socio-economic effects
Coastal squeeze: negative socio-economic effects
Uruguayan coast:
Increase in temperature, and in the frequency, intensity and speed of onshore winds
y = 0.28x + 1.63R²= 0.44***
1.2
1.4
1.6
1.8
2.0
2.2
-0.4 0.1 0.6 1.1Sea surface temperature anomalies (ºC)
Win
d sp
eed
anom
alie
s (m
.s-1
) 2007
20112008
2006
1989
1990
1993
1988
y = 0.28x + 1.63R²= 0.44***
1.2
1.4
1.6
1.8
2.0
2.2
-0.4 0.1 0.6 1.1Sea surface temperature anomalies (ºC)
Win
d sp
eed
anom
alie
s (m
.s-1
) 2007
20112008
2006
1989
1990
1993
1988
Increase in temperature, onshore winds and extreme events
y = 0.45x - 879.54R2 = 0.80***
10
12
14
16
18
20
22
24
1991 1995 1999 2003 2007 2011
Year
Swas
h w
idth
(m)
Long-term increase in wave height, swash width, and decrease in beach slope EROSION
Ortega et al. 2013, Defeo et al. 2013
Hall 2011, Defeo & Castilla 2012, Defeo et al. 2013
Climate fluctuations affect the social-ecological system
Habitat Fauna
Society
Loss of intertidal habitat, catchability, fishing days and $$$
10
12
14
16
18
20
22
24
1985 1986 1987 1990 2009 2010 2011
January
February
10
12
14
16
18
20
22
24
1985 1986 1987 1990 2009 2010 2011
January
February
Num
ber o
f fis
habl
e da
ysPerception of fishers: fishing days
Much less Less Normal More Much more
0
> 95% of species, abundance and biomass made up by three taxa:• Crustaceans (isopods, amphipods, hippids, mysids, decapods)
• Molluscs (bivalves and gastropods)• Polychaete worms
Sandy beach macrofauna
Excirolana
Mesodesma
Glycera
How do they respond to How do they respond to the beach environment the beach environment and climate variability?and climate variability?
Mesodesma donacium
Mesodesma mactroides
4ºS
50ºS
24ºS
41ºS
Mesodesma donacium
Mesodesma mactroides
4ºS
50ºS
24ºS
41ºS
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1969 1974 1979 1984 1989 1994 1999 2004
Cat
ch (t
on)
Peru
0
4000
8000
12000
16000
20000
1965 1970 1975 1980 1985 1990 1995 2000 2005
Cat
ch (t
on)
Chile
0
4000
8000
12000
16000
20000
1965 1970 1975 1980 1985 1990 1995 2000 2005
Cat
ch (t
on)
Chile
Almost collapsed fishery stocks, despite management strategies (area-based + co-management) that succeeded in other benthic fisheries (Chile, Uruguay)
0
2000
4000
6000
8000
10000
12000
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
Year
Abu
ndan
ce (i
nd/m
)
0
2000
4000
6000
8000
10000
12000
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
Year
Abu
ndan
ce (i
nd/m
) Mesodesma mactroidesUruguay-Brazil-Argentina
Sandy beach clams – Pacific – Atlantic South America
Sandy beach clams: mass mortalitiesMass mortalities of this cold-water clams during the last 2 decades decimated populations
throughout entire distribution ranges in the Atlantic and Pacific:
1. Important SOCIAL-ECOLOGICAL SYSTEMS: fisheries and human livelihoods affected
2. Community structures and ecosystems drastically changed
3. Possible causes: fishing PLUS temperature increase, algal blooms, diseases
Brazil – Uruguay – Argentina
Peru - Chile
Fiori et al. 2004, Fiori & Defeo 2006, Oderbrecht et al 2009
0
2000
4000
6000
8000
10000
12000
19601963196619691972197519781981198419871990199319961999200220052008
Year
Abu
ndan
ce (I
nd.m
-1)
-3
-2
-1
0
1
2
3
AM
O (c
umul
ativ
e su
m)
Atlantic Multidecadal Oscillation
Reg
ime
shift
Reg
ime
shift
Mass mortalities
Increase in temperature
Defeo & Castilla 2012, Ortega et al. 2012, 2013, Schloeman et al. 2014
SSTA
Atlantic yellow clam: mass mortalities and increasing temperature
Mass mortalities: negative socio-economic effects
Mass mortalities that began in late 1993
Closed fishery until 2008, without showing evidence of stock recovery, particularly in the adult (harvestable) stock
Ortega et al. 2012, 2013, Defeo et al. 2014
Pacific surf clam: mass mortalities, ENSO and fishery collapse
Ortega et al. 2012
ENSO affected landings in Peru and Northern Chile: closed season in Peru since 1999…
Unit price: another significant predictor of long-term trends
ENSO
Ecological effects of climate variability: tropicalization
0
20
40
60
80
100
1982 1984 1986 1988 1990 1992 1994 1996 1998 2000
Mesodesma mactroides
Donax hanleyanus
Emerita brasiliensis
Adu
lt ab
unda
nce
(%) Ex
perim
enta
lm
anag
emen
t
80
60
40
Jun ´81
20
100
Dec ´81 Jun ´82 Dec ´82 Jun ´83 Oct ´83
Freq
uenc
yby
num
ber
(%)
Donax
peruvianus
Emerita analogaOthers
Mesodesma donacium EL NIÑO
´ ´ Jun ´82 Dec ´82 Jun ´83 Oct ´83
(%)
Others
Massive mortalities of yellow clam
1. Increasing SST
2. Phytoplankton biomass,
composition and
intensity of blooms
3. Benthic community
structure
4. Population abundance
5. Persistence of invasive
species
6. Range shifts
Changes being assessed:
Blooms
Climate change and transitional waters
Basset et al. 2013, Schoeman et al. 2014
Changes in:
• Temperature• Precipitations• Sea level• Water runoff
Hypotheses to be tested:
• Spp composition shifts• Expansion of exotic species
(Corbicula)?• Increase in mortality of
marine species
Uruguay
Environment EcosystemProcesses, functions
Biodiversity
Abundance/structure
Managementtools
TimeSpace SpeciesSizesEffort
Fisheries
Tourism
Protection to extreme events
Long term management policies
Sandy beach management requires the integration of ecology with socio-economic and institutional factors
Governance modes and institutional
structuresGovernment-based
Co-managementDecentralized
UNCERTAINTY
Ecological, Statistical, Socio-economic, Governance
Sandy beaches as social-ecological systems
Services
1. Different lines of evidence support a climate change interpretation as a primary causal agent in sandy beaches
2. Effects on the environment:
a. Coastal squeeze (sea level rise and urbanization)
b. Changes in beach morphodynamics: erosion
c. Increase in swash width
3. Effects on macrofauna:
a. Biodiversity loss: a major driver of ecosystem change (regime shifts)
b. Across taxa: similar effects in parallel communities (Atlantic and Pacific)
Conclusions: sandy beaches & climate variability
Conclusions: sandy beaches & climate variability
1. Biophysical changes affected socio-economic issues: sandy beaches as social-ecological systems
2. Effects of climate variability swamped management measures
3. Long-term policies, early warning systems (e.g. red tides) and co-governance of SES are needed
4. Institutional adaptive capacity to cope with climatic and human drivers of change
Gutierrez et al. 2011 - Nature