Long term mesozooplankton changes in coastal waters of North Spain

Ricardo González-Gil F. González-Taboada, J. Höfer, R. Anadón University of Oviedo

Department of Biology of Organisms and Systems In colaboration with

Instituto Español de Oceanografía

The study area

   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

Oceanic Station Shelf-break Station Coastal Station Ricardo González-Gil

1.

Analysis of mesozooplankton changes

Long-term trends

2.

1.

2.

Other underlying aspects of these long term trends: Modifications in seasonality Effects from changes in the interannual environmental conditions: variations of the Central Water mass regime

Ricardo González-Gil

The study variables



Biological 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 trends

Zooplankton time series context in the North Atlantic Ocean Criteria

•Current data: Data at least until 2008 •Sampling frequency: every month 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/

Ricardo González-Gil

Long-term trends

Dummy variable seasonal regression

Y t



a



bt



c

1

Jan



c

2

Feb

 ...



c

11

Nov

 

t

Long-term trend component Seasonal component Random or noise component Time Time Time Ricardo González-Gil

Chl a *

Long-term trends (1993-2010)

Zoo BM ** *** *** Zoo abundance *

•

Positive trends for all the variables.

•

Only highly significant for Zoo BM.

P-value *** <0. 001 ** <0.01

* <0. 05 <0. 1 Ricardo González-Gil

Long-term trends (1998-2010). Fractionated biomass 200 500 µm 500- 10 00 µm > 1000 µm

•

Positive trends *** *** *** **

•

Unexpected compared to other works: More intense, significant and explanatory trends at larger fractions ** *** *** * P-value *** <0. 001 ** <0.01

* <0. 05 <0. 1 Ricardo González-Gil

•

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

•

Decreasing significance towards deeper waters

Long-term trends (1993-2010)

Temperature Atm.

Effect Ricardo González-Gil

Changes in seasonality

10 m depth Temperature Ricardo González-Gil

Changes in seasonality

Chl a Earlier spring bloom/more intense spring and autumn bloom Ricardo González-Gil

Changes in seasonality

Zooplankton biomass more intense spring and autumn peak Ricardo González-Gil

Variations of Central Water masses

ENACWsp (subpolar gyre) BBCW (Celtic sea)

•

BBCW



Bay of Biscay Central Water

•

ENACWsp



East North Atlantic Central Water subpolar mode

•

ENACWst



East North Atlantic Central Water subtropical mode

•

IPC



Iberian Poleward Current/Navidad IPC Modified from Pérez et al. 2001 ENACWst (Subtropical gyre) Ricardo González-Gil

Variations of Central Water masses

•

Identification: T-S profiles

•

Marked periods

: •For BBCW •For ENACWst

Ricardo González-Gil

Variations of Central Water masses

Ricardo González-Gil

Variations of Central Water masses

Influence on biological variables ANOVA: No significant differences Ricardo González-Gil

Zoo abundance 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 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.

Ricardo González-Gil

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 .

Station

E1 P-value for long term trend(Seasonal regression): 1993-2010 P-value for long term trend(Seasonal regression): 1998-2010

log10_Chla

0.01060925

log10_Bm_ zooplank

0.00000484

log10_abund _zooplank

0.02725876

log10_Bm_200_ zooplank

0.02490764

log10_Bm_ 500_zooplank

0.00064670

log10_Bm_ 1000_zooplank

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

Ricardo González-Gil

Ricardo González-Gil