Validating physical-biological models and anchovy IBMs in the N Alboran Sea. Survey IBMALBOR1

SESAME. WP3-WP5

I. Catalan & B. Morales-Nin

OBJECTIVES OF THE SURVEY

GENERAL OBJECTIVES

• To gather simultaneous physical and biological data of relevance for validating, in a Lagrangian scheme, the early life history of E. encrasicolus in relation to the environment.

• To obtain physical data for validating current 3-d hydrodynamic models in the Alboran Sea.

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•Severe decline of anchovy since the 80s

•85% of south Mediterranean anchovy is landed on the Bay of Malaga. 0 Age-class

•High interanual variability in landings

GFCM 2005

WHAT IS KNOWN: THE FISHERY PROBLEM

•Peak spawning in July-August. 19-23°C. Around the Malaga Continental shelf. Nursery inside Malaga Bay.

WHAT IS KNOWN: REL. WITH THE ENVIRONMENT

•Upwelling effects are detectable in the area of spawning during summer. Chlorophyll a is significantly associated to NO3-.

Agostini and Bakun 2002

•Higher anchovy larval growth rates are related to higher production and mesozooplancton, and sporadic evidence shows that recruitment increases after these periods of high growth-rates.

WHAT IS KNOWN: REL. WITH THE ENVIRONMENT

•The coastal oceanography around the spawning area is less known than the Alboran jet and gyres, and is a key piece to understand the anchovy dynamics in the N Alboran Sea .

•The concrete location of the nursery area makes this area of particular interest to apply individual based-models, coupled to 3-d physical-biological models. This excercise needs validation tools, which can be gathered from lagrangian surveys

OBJECTIVES OF THE SURVEY

SPECIFIC OBJECTIVES

Oceanography:

-Characterise the coastal circulation and vertical hydrographic structure in the area of maximum importance for anchovy spawning and nursery in N Alboran (Useful for IBMs).

-Providing boundary conditions for the hydrodynamic models that are currently being implemented in the area.

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OBJECTIVES OF THE SURVEY

SPECIFIC OBJECTIVES

Biology:

- Eulerian: To gather data on horizontal distribution of eggs, larvae and post-larvae, and concurrent potential food (microzooplankton) and hydrography (grid).

- Lagrangian: Resolving the spatial structure of anchovy ELH through time, including growth and feeding ecology. Following a drifter for at least 24 h should be a must for that purpose.

- Back-calculations: Collect post-larvae from the defined nursery area (Bay of Malaga), in order to analyse the otolith growth and infer past growth rates and hatching dates (useful to run drifting-IBM simulations)

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METHODS AND SURVEY PLAN. I

A. Vessel and allocated time

Characteristics

Length: 34mBeam: 7.70Draught: 4mPuntal: 4.20mSpeed: 14 knotsCrew: 8Scientists:8 Onboard Scientific equipment

1 Laboratory1 ADCP 1-CTD-Rossette (12 bottles) 1 Crane 16 T

R/V Regina Maris, Junta de Andalucía

The vessel is reserved for 17-25 of July 2008 (9 days)

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METHODS AND SURVEY PLAN (PRELIMINARY). II

A. Preliminary characterisation of the 3-d hydrographic structure using gliders:

• CTD• Fluorescence• Oxygen• Turbidity

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B. Eulerian. Grid of Stations plus at least one long transect to provide boundary conditions for the hydrodynamic models in the area (IMEDEA)

At each station, monitor:1) Vertical hydrographic profiles of T,S, fluorescence (CTD).2) Nutrients and Chl (Niskin bottles)3) Microzooplankton (potential food, Juday-Bogorov (53) vertical at

2 depths) and Meso-Ichthyoplankton (Multinet Hydrobios, 335 and 200 microns, 2x2 depths)

METHODS AND SURVEY PLAN (PRELIMINARY). IIISESAME. WP3-WP5

B. Eulerian. Multinet Used for sampling meso and ichthyoplankton (below and above the thermocline)

METHODS AND SURVEY PLAN (PRELIMINARY). IV

Net Frame of stainless steel with pressure capsuled motor unit, integrated depth meter 0-3000 metres, canvas part with zip fasteners, net opening 50 x 50 cm = 0.25 m². Power supply: batteries.

Equipped with 200 and 335 micrometer nets to collect mesozooplankton and ichthyoplankton.

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C. Lagrangian

METHODS. V

Deploy 4 GSM-based coastal drifters to track coastal water masses at -10 m, with the aim of: 1) characterising the coastal surface flow close to the nursery area, particularly in relation to the upwelling and retention areas

2) following a population of anchovy eggs and larvae to extract data on daily growth, vertical distribution of prey and predators, and feeding parameters for anchovy models.

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C. Lagrangian. The drifters

METHODS. VI

The MD02 surface drifter is a low-cost small coastal Lagrangian drifter. It is designed as a very small and security-oriented buoy, having a flexible closed cell PE foam buoyancy. Being a coastal buoy, its position is obtained by a GPS module, and it has a GSM data transmission system. It can be configured by the software to send the data at specified time intervals. It has two different running modes, where the GSM module is asleep or awake. In the total sleep mode, it only transmits its position at the specified time intervals.In normal running mode it can send the SMS at the specified time or on request and it can be reconfigured at any time.

The drifters are made by Albatros S.L, a company that was found as a spin-off company from IMEDEA (CSIC/UIB) http://albatrosmt.com/

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D. Back-calculations:

Conduct a series of surface night hauls (bongo 90, 500um meshes) at the bay of Malaga to fish for postlarvae that will be used for back-calculating growth trajectories and birthdates, useful for validating IBMs.

METHODS. VII

NURSERY AREA

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Thank you

Regional modelling and field work in the Alboran Sea: Summary

• Hydrodynamic models: ROMS / POM

• Biogeochemical models: NPZD / BFM

• Individual-based models (IBM)

Models’ data needs Solution approach

Oceanographic data Gliders, cruises, altimetry

Biological data (anchovy - Lagrangian) Cruises, drifters (Lagrangian)

Biogeochemistry (Eulerian) Cruises (Eulerian)

Meteorological data Spanish MeteorologicalInstitute (INM)