Table 1. Summary of environmental and ecosystem measurements and trends.


Data 1950–1960 1961–1970 1971–1980 1981–1990 1991–2000 2001–2010 Trend
ENVIRONMENTAL 
  
  
  
  
  
  
  
In situ, local 
  
  
  
  
  
  
  
Air temperature
(decadal mean of annual averages, ºC)1,2 
 24.3 
 24.0 
 24.3 
 24.5 
 25.0 
 25.4 a 
 Upward trend +0.023 ºC y-1 (P < 0.001); Fig. 2a 
SST (box 81, ºC)3 
 25.7 
 25.7 
 25.8 
 26.2 
 26.4 
 26.5 b 
 Upward trend +0.0186 ºC y-1 (P < 0.001); Fig. 2a 
Rainfall (decadal mean of cumulated annual, mm)1,2 
 504 
 539 
 414 
 361 
 347 
 384 
 High variability, downward tendency -1.30 mm y-1 (P > 0.05, ns); Fig. 2b 
Turbidity (mean Secchi disk depth, m)4,5 
 - 
 8.1 /
5.2 c 
 - 
 - 
 - 
 12.0 /
6.0 c 
 At both stations, lower turbidity in 2007–2008 than in 1970s 
Nutrients (means, µM)5
Nitrate /
Ammonia /
SRP 
 - 
 - 
 - 
 - 
 - 
0.37 /
0.09 /
0.19 d 
 Generally oligotrophic, occasionally mesotrophic conditions 
Chlorophyll a (mean, µg L-1)5 
 - 
 - 
 - 
 - 
 - 
 0.28 /
0.66 c  
 Low concentrations for coastal area under estuarine influence 
Proxies, local 
  
  
  
  
  
  
  
SST anomaly Ranobe lagoon relative to 1961–1990 mean (δ18O)6,7 
 -0.032 
 -0.196 
 -0.102 
 0.298 
 0.74 
 - 
 Upward trend 0.016ºC y-1 (P < 0.001); SST rise of 0.72°C between 1950–1995 
Sediment runoff (Ba/Ca, µmol mol-1)7
GRT-1 /
GRT-2  

-
- 

-
- 

5.59 /
5.51 

5.48 /
5.36 

5.93 /
5.34 

6.73 /
5.89 

 2-y upward trend GRT1 +0.045 µmol mol-1 y-1 (P < 0.001); GRT2: +0.012 µmol mol-1 y-1 (P < 0.02); strong sediment pulses during peak river discharges; higher base level since 1998 
Regional 
  
  
  
  
  
  
  
Onilahy River flow
(decadal mean of annual average, m3 s-1)8,9 
 123 
 154 
 79e 
 - 
 - 
 - 
 Downward trend (P < 0.001) but data gaps post 1978 might inflate the trend; Fig. 2c 
SST (decadal means of annual average in South Mozambique Ch., °C)3 
 24.8 
 24.8 
 25.2 
 25.3 
 25.3 
 25.4 c 
 Upward trend +0.0133ºC y-1 (P < 0.001) 
ENSO /
IOD10,11,12 
 -0.30 /
- 
 -0.18 /
0.09 
 -0.18 /
-0.02 
 0.37 /
0.03 
 0.48 /
0.01 
 0.20 /
0.13 
 Strongly positive ENSO since 1980s; increasing climate variability due to 20th century mode shifts IOD  
Tropical cyclones passing <100 km from GRT13,14 
 9 
 3 
 5 
 3 
 4 
 5 
 No trend in overall cyclone frequency 
ECOLOGICAL 
  
  
  
  
  
  
  
Coral cover (%)15,16,17
Outer reef slope (6–10 m) /
Reef flat /
Inner reef slope 
 - 
30–100 /
50–100 /
80–100 
 - 
 - 
 - 
15–30 /
1–2 /
2–20 
 Generalized loss of coral cover, most pronounced on reef flat 
Number of coral genera15,18
Outer reef slope (≤15 m) /
Reef flat /
Seagrass /
Grande Vasque /
Inner reef slope /
Overall 
 - 

31 /
38 /
26 /
39 /
52 /
56 
 -  
 -  
 -  

43 /
30 /
8 /
49 /
48 /
61 
 Loss of coral generic diversity from shallow habitats 
SOCIOECONOMICS 
  
  
  
  
  
  
  
Human population Toliara town and suburbs19,20,21 
 - 
 37,000 
 46,000–60,000 
 81,000–100,000 
 140,000 
 >200,000 
 Increasing by 3–4% per year. After 1980, rural exodus from SW Madagascar results in >40% growth of Toliara population25 
Human population Toliara district22,23 
 - 
 - 
 - 
 130,000f 
 - 
 190,000f 
 Strong increases in coastal population
Strong increases in fishing pressure 
Number of fishermen Toliara district22,23,24 
 - 
 ca. 800 
 - 
 1556 
 - 
 1715 
CPUE (kg d-1)21,25,26
Line /
Gillnet /
Seine 
- /
50–100 /
≤1000 
 - 
 - 
  
4–6/
12.5–27.7/
25.6–39.7 
 - 
2.5–2.6 /
6.5–7.4 /
14.5–18.0 
 Strong declines in fisheries yields since the 1950s; between 1989 and 2009, yield per fisherman per day fell by ca. 50% regardless of gear 
CPUE(kg d-1fisherman-1)21,26
Gillnet/
Seine 
 -  
 - 
 - 
5.2–8.2 /
5.9–10.6 
 - 
2.9–3.6 /
5.4–5.5 

a Average 2001–2007 period; b Average 2001–2005 period; c Stations: North passage / lagoon; d Lagoon; e Average 1971–1978 period; f Includes communities Besakoa, Mahavatse II, and Mahavatse I, Ankilibe, Sarodrano, and St. Augustin; g Catches in respectively cool and hot seasons.

1 ASECNA 1950–2007; 2 IRD 2007–2008; 3 HadISST1 monthly SST; 4 Gaudy 1973; 5 Arfi et al. 2006, 2007; 6 Coral core from Ifaty covering 1660–1995 (Zinke et al. 2004); 7 Four cores from Ifaty and GRT covering 1975–2008 (Maina et al. 2012; J.Z., unpublished results); 8 ORSTOM Laboratoire d’Hydrologie (1950–1960); 9 Direction de la Météorologie et de l’Hydrologie of Madagascar (1961–1978, 1987, 1995, 1996, partial data for 1990, 1992, 1993); 10 http://www.esrl.noaa.gov/psd/enso/mei/; 11 Abram et al. 2008; 12 Nakamura et al. 2009; 13 http://australiasevereweather.com/tropical_cyclones 14; Kuleshov et al. 2010; 15 Pichon 1978; 16 Harris et al. 2010; 17 FMAR and JHB, unpublished results; 18 MMMG, MP, FMAR and JHB, unpublished results; 19 Salomon 1986; 20 Vasseur et al. 1988; 21 Laroche et al. 1997; 22 Laroche and Ramananarivo 1995; 23 Randriambololona 2009; 24 Bellemans 1989; 25 Lagouin 1959; 26 FR and JHB, unpublished results


Erratum: After publication of this manuscript, changes were made to the author affiliations, acknowledgments, and Table 1. The changes were made on 17 January 2013.