Long term mesozooplankton changes in coastal waters of North

Spain

Ricardo González-GilF. González-Taboada, J. Höfer, R. Anadón

University of Oviedo Department of Biology of Organisms and Systems

In colaboration with

Instituto Español de Oceanografía

Ricardo González-Gil

Long-term monitoring program RADIALES by the Spanish Institute of Oceanography (Instituto Español de Oceanografía, IEO) in collaboration with the UO

Cantabrian Sea Offshore of Cudillero (Asturias)

Monthly sampling January 1993 to December 2010

The study area

Coastal Station

Shelf-break Station

Oceanic Station

Ricardo González-Gil

Analysis of mesozooplankton changes1. Long-term trends

2. Other underlying aspects of these long-term trends:

1. Modifications in seasonality2. Effects from changes in the

interannual environmental conditions: variations of the Central Water mass regime

Ricardo González-Gil

The study variablesBiological variables:

Mesozooplankton variables

Biomass Fractionated biomass (200-500 μm, 500-1000 μm, > 1000 μm) Abundance

Phytoplankton variables

Integrated Chl a, from 50 m to the surface

Physical variables:

Temperature Salinity on the isopycnal 27. 1 Marker for Central Water mass types

Ricardo González-Gil

Long-term trendsZooplankton time series context in the North Atlantic Ocean

Data from Global comparisons of zooplankton time series (SCOR WG 123). Time series also associated with the ICES-WGZE(ICES Working Group on Zooplankton Ecology) http://wg125.net/

Criteria

• Current data: Data at least until 2008

• Sampling frequency: every month

Ricardo González-Gil

Long-term trends

Dummy variable seasonal regression

tt NovcFebcJancbtaY 1121 ...

Time

Long-term trend component

Time

Seasonal component

Time

Random or noise component

Ricardo González-Gil

***

******

*

Long-term trends (1993-2010)

P-value

*** <0. 001

** <0.01

* <0. 05

<0. 1

• Positive trends for all the variables.

• Only highly

significant for Zoo BM.

Chl a Zoo BM Zoo abundance

Ricardo González-Gil

P-value

*** <0. 001

** <0.01

* <0. 05

<0. 1

*

*****

***

***

***

***

**

Long-term trends (1998-2010). Fractionated biomass• Positive trends

• Unexpected compared to other works: More intense, significant and explanatory trends at larger fractions

200-500 µm 500- 1000 µm > 1000 µm

Ricardo González-Gil

Long-term trends (1993-2010) Temperature

• Warming trends: higher and more significant for the more oceanic station (more stable conditions)

• Decreasing significance towards deeper waters

Atm.Effect

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Changes in seasonality

10 m depth Temperature

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Changes in seasonalityChl a

Earlier spring bloom/more intense spring and autumn bloom

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Changes in seasonalityZooplankton biomass

more intense spring and autumn peak

Ricardo González-Gil

ENACWsp(subpolar

gyre)

BBCW(Celtic sea)

ENACWst(Subtropical

gyre)

IPC

Modified from Pérez et al. 2001

• BBCWBay of Biscay Central Water

• ENACWspEast North Atlantic Central Water subpolar mode

• ENACWstEast North Atlantic Central Water subtropical mode

• IPCIberian Poleward Current/Navidad

Variations of Central Water masses

Ricardo González-Gil

Variations of Central Water masses• Identification: T-

S profiles

• Marked periods:

• For BBCW• For ENACWst

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Variations of Central Water masses

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Variations of Central Water massesInfluence on biological variables

ANOVA: No significant differences

Ricardo González-Gil

ANOVA and Tukey tests results:

Significant differences for E2 (shelf-break station)

• Highly significant differences between ENACWst and ENACWsp

• Significant differnces between ENACWst and BBCW

Zoo abundance

Ricardo González-Gil

Conclusions• For the long term trends:

• Detection of significant positive trend for Zooplankton biomass.

• Positive long term trends for all the biomass fractions. Unexpected more intense and markedly positive long term trends for larger zooplankton fraction sizes.

• For Changes in seasonality:

• For Chl a: Earlier spring bloom/more intense spring and autumn bloom.

• For zooplankton biomass: more intense spring and autumn peak.

• For variations of the Central Water mass regime

• Effect on the zooplankton abundance for the shelf-break station.

ACKNOWLEDGEMENTS

This work was supported by a grant from the Ministerio de Educación del gobierno de España (FPU grant) and by the Instituto Espanñol de Oceanografía (Project Radiales)

Thanks to:

The crew of the research vessel José Rioja ;

The people from the ecology area of the University of Oviedo for advice and guidance;

Thank you also for all the support and advice from loved ones.

Ricardo González-Gil

P-value for long term trend(Seasonal regression): 1993-2010 P-value for long term trend(Seasonal regression): 1998-2010

Station log10_Chla log10_Bm_ zooplank log10_abund _zooplank log10_Bm_200_

zooplanklog10_Bm_

500_zooplanklog10_Bm_

1000_zooplank

E1 0.01060925 0.00000484 0.02725876 0.02490764 0.00064670 0.00009204

E2 0.06127331 0.00055801 0.25373958 0.17635892 0.00017461 0.00000058

E3 0.08910399 0.00487024 0.05275587 0.00528685 0.00003303 0.00112041

Ricardo González-Gil

BB

CW

Ricardo González-Gil

EN

AC

Wst