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Assessment of the climate and human impact on estuarine water environments in two estuaries of the Bay of Biscay Cover

Assessment of the climate and human impact on estuarine water environments in two estuaries of the Bay of Biscay

Oceanological and Hydrobiological Studies
Volume 45 (2016): Issue 4 (December 2016)
By: Arantza Iriarte,  Fernando Villate,  Ibon Uriarte and  Santiago Arranz  
Open Access
|Dec 2016

Figures & Tables

Figure 1

Maps of the Bilbao and Urdaibai estuaries, showing the usual extent of water masses of 35, 34, 33, 30 and 26 salinity below the halocline during neap tides and high water. The map of the river catchment areas, showing the location of the meteorological and hydro-meteorological stations is also shown.
Maps of the Bilbao and Urdaibai estuaries, showing the usual extent of water masses of 35, 34, 33, 30 and 26 salinity below the halocline during neap tides and high water. The map of the river catchment areas, showing the location of the meteorological and hydro-meteorological stations is also shown.

Figure 2

Averaged inter-annual, seasonal and residual variability (SDy,m,ε) of air temperature, rainfall for the sites of Sondika (S), Abusu (A) and Muxika (M) and river flow for the Kadagua (K), Ibaizabal-Nerbioi (I-N) and Oka (O) rivers
Averaged inter-annual, seasonal and residual variability (SDy,m,ε) of air temperature, rainfall for the sites of Sondika (S), Abusu (A) and Muxika (M) and river flow for the Kadagua (K), Ibaizabal-Nerbioi (I-N) and Oka (O) rivers

Figure 3

Averaged inter-annual, seasonal and residual variability (SDy,m,ε), and time-series average values of the stratification index (ST) and Secchi disk depth (SDD, m) in the estuaries of Bilbao (A and C) and Urdaibai (B and D)
Averaged inter-annual, seasonal and residual variability (SDy,m,ε), and time-series average values of the stratification index (ST) and Secchi disk depth (SDD, m) in the estuaries of Bilbao (A and C) and Urdaibai (B and D)

Figure 4

Averaged inter-annual, seasonal and residual variability (SDy,m,ε), and time-series average values of temperature below the halocline (A and B) and in the halocline (C and D) in the estuaries of Bilbao and Urdaibai. 30* – above the halocline and 35* – the whole water column
Averaged inter-annual, seasonal and residual variability (SDy,m,ε), and time-series average values of temperature below the halocline (A and B) and in the halocline (C and D) in the estuaries of Bilbao and Urdaibai. 30* – above the halocline and 35* – the whole water column

Figure 5

Averaged inter-annual, seasonal and residual variability (SDy,m,ε), and time-series average values of DOS below the halocline (A and B) and in the halocline (C and D) in the estuaries of Bilbao and of Urdaibai. 30* – above the halocline and 35* – the whole water column
Averaged inter-annual, seasonal and residual variability (SDy,m,ε), and time-series average values of DOS below the halocline (A and B) and in the halocline (C and D) in the estuaries of Bilbao and of Urdaibai. 30* – above the halocline and 35* – the whole water column

Figure 6

Averaged inter-annual, seasonal and residual variability (SDy,m,ε), and time-series average values of chlorophyll a in the estuaries of Bilbao (A) and Urdaibai (B)
Averaged inter-annual, seasonal and residual variability (SDy,m,ε), and time-series average values of chlorophyll a in the estuaries of Bilbao (A) and Urdaibai (B)

Figure 7

Principal component analysis of the seasonal changes in the water environmental variables (ST: Stratification index; SDD: Secchi disk depth; WTT: Water temperature for the total water column; WTB: Water temperature below the halocline; WTH: Water temperature in the halocline; WTS: Water temperature in the surface layer above the halocline; DOT: Dissolved oxygen for the total water column; DOB: Dissolved oxygen below the halocline; DOH: Dissolved oxygen in the halocline; DOS: Dissolved oxygen in the surface layer above the halocline; CHL: Chlorophyll a at different salinity sites of the Bilbao and Urdaibai estuaries
Principal component analysis of the seasonal changes in the water environmental variables (ST: Stratification index; SDD: Secchi disk depth; WTT: Water temperature for the total water column; WTB: Water temperature below the halocline; WTH: Water temperature in the halocline; WTS: Water temperature in the surface layer above the halocline; DOT: Dissolved oxygen for the total water column; DOB: Dissolved oxygen below the halocline; DOH: Dissolved oxygen in the halocline; DOS: Dissolved oxygen in the surface layer above the halocline; CHL: Chlorophyll a at different salinity sites of the Bilbao and Urdaibai estuaries

Figure 8

Cumulative sums of month scores from January to December in PC1 and PC2 for different salinity sites of the Bilbao (A and C) and Urdaibai (B and D) estuaries. *Inverse values: positive values are reported as negative values and vice versa.
Cumulative sums of month scores from January to December in PC1 and PC2 for different salinity sites of the Bilbao (A and C) and Urdaibai (B and D) estuaries. *Inverse values: positive values are reported as negative values and vice versa.

Figure 9

Patterns of seasonal (SDm) and inter-annual (SDy) variability of water temperature at 35, 34, 33, 30 and 26 salinity sites in the estuaries of Bilbao (A, C, E and G) and Urdaibai (B, D, F and H). BH and H indicate below halocline and halocline waters, respectively. The dashed line for the above halocline layer at the 30 salinity site in the Bilbao estuary. At 35 salinity in the estuary of Urdaibai, the data are provided for the whole water column.
Patterns of seasonal (SDm) and inter-annual (SDy) variability of water temperature at 35, 34, 33, 30 and 26 salinity sites in the estuaries of Bilbao (A, C, E and G) and Urdaibai (B, D, F and H). BH and H indicate below halocline and halocline waters, respectively. The dashed line for the above halocline layer at the 30 salinity site in the Bilbao estuary. At 35 salinity in the estuary of Urdaibai, the data are provided for the whole water column.

Figure 10

Principal component analysis of inter-annual changes in water environmental variables (acronyms as in Figure 7) at different salinity sites in the estuaries of Bilbao and Urdaibai
Principal component analysis of inter-annual changes in water environmental variables (acronyms as in Figure 7) at different salinity sites in the estuaries of Bilbao and Urdaibai

Figure 11

Cumulative sums of year scores from 1998 to 2008 in PC1 and PC2 for different salinity sites in the estuaries of Bilbao (A and C) and Urdaibai (B and D)
Cumulative sums of year scores from 1998 to 2008 in PC1 and PC2 for different salinity sites in the estuaries of Bilbao (A and C) and Urdaibai (B and D)

Results of (Spearman rank) correlation analyses of the first (C1) and second (C2) components of PCA with the annual anomalies in rainfall, Kadagua and Oka river flows (RF) and summertime air temperature anomalies from different salinity sites (35, 34, 33, 30, 26) of the Bilbao (B) and of Urdaibai (U) estuaries_ Only the p-values of significant correlations (in bold) are shown_

SitePCA componentAir temperatureRainfallKadagua (RF)Oka (RF)
B35C1-0.0360.4590.066
C20.882(p<0.001)-0.041-0.005
B34C10.736(p<0.01)0.1660.107
C2-0.4090.139-0.158
B33C10.609(p<0.05)-0.230-0.358
C2-0.0180.2830.066
B30C1-0.0270.4720.674(p<0.05)
C2-0.3270.2510.110
U35C10.891(p<0.001)0.096 0.093
C20.227-0.318 -0.353
U33C10.700(p<0.05)-0.041 -0.201
C2-0.3640.271 0.263
U30C10.773(p<0.01)0.057 -0.048
C2-0.1090.042 0.040
U26C10.4910.295 0.184
C20.100-0.718(p<0.05) -0.748(p<0.01)
DOI: https://doi.org/10.1515/ohs-2016-0043 | Journal eISSN: 1897-3191 | Journal ISSN: 1730-413X
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Language: English
Page range: 505 - 523
Submitted on: Feb 9, 2016
|
Accepted on: Apr 13, 2016
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Published on: Dec 12, 2016
Published by: University of Gdańsk
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
estuaries,
environmental variability,
temperature,
climate,
anthropogenic impact,
Bay of Biscay
Related subjects:
Chemistry,
Chemistry, other,
Geosciences,
Geosciences, other,
Life sciences,
Life sciences, other

© 2016 Arantza Iriarte, Fernando Villate, Ibon Uriarte, Santiago Arranz, published by University of Gdańsk
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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