Estación de Ciencias Mariñas de Toralla

ECIMAT

Short and Long-term effects of salinity stress episodes on Cerastodema edule: Thread drifters vs. Sedentary settlers

L G Peteiro, D Costas, A Martinez, N Costoya, R Rodriguez, S Gonzalez, D Villafaña,

C Olabarria, E Vázquez

Ph

oto

: La

van

dei

ra jr

(La

Op

inio

n A

Co

ruñ

a)

26/10/2016

21/01/2016

24/04/2016

28172 Tm

2015 FAO- Global Production Statistics

Spain/Galicia ≈ 10% of European

production

2015

C. edule

Ph

oto

: P

.S.

(El C

orr

eo G

alle

go)

Trocophore Veliger

Pediveliger

Thread-drifters

Primary settlement

Secondary Settlement

juveniles

♀ ♂

May-July

4-5 weeks

Thread-drifters

juveniles

♀ ♂

Salinity Optimum: 25 (Verdelhos et al. 2015)

Salinity Optimum: 30-35 (Kingston,1974)

Primary settlement

Secondary Settlement

May-July

?

What are the physiological responses of early-settlers to drops in salinity?

Do they differ between thread-drifters and sedentary juveniles?

Experimental Design:

2 size classes:

-Sedentary Settlers ≈ 8mm

-Thread-drifters ≈ 4mm

4 replicates x 8 Salinity treatments:

2, 5, 10, 15, 20, 25, 30 and 35

Physiological measurements:

-Oxygen Consumption

-Clearance Rate

-Ammonium Excretion

-Mortality

-Growth

Day 2 and Day 7

Spat reared at the laboratory Salinity 35

1 Week

DAY 2 Acute stress

Isolation reflex >10 Linear increase

<20

<10

>20 ≈ Plateau

Isolation reflex >25 ≈ Plateau

<10

<10

>20 ≈ Plateau

DAY 2 Acute stress

Isolation reflex <10

<10

DAY 2 Acute stress

Regulation of FAAP

Ammonium excretion

Isolation reflex <10

<10

DAY 2 Acute stress

Regulation of FAAP

Ammonium excretion

DAY 2 Acute stress

ANOVA; p<0.001

ANOVA; p=0.716

ANOVA; p<0.001

ANOVA; p=0.073

Length

Weight

No activity bellow 15 Isolation reflex Progresive increase with salinity

No activity bellow 15 Isolation reflex 100% Mortality at day 4 bellow 15 Anaerobic metabolism

At day 7 no more differences between salinities

Acclimation

Acclimated

DAY 7 Acclimation

DAY 7 Acclimation

Acclimated

Not yet!

DAY 7 Acclimation

ANOVA; p<0.001

ANOVA; p=0.944

ANOVA; p<0.001

ANOVA; p=0.779

Length

Weight

Thread-drifters

juveniles

♀ ♂

Salinity Optimum: 25 (Verdelhos et al. 2015)

Salinity Optimum: 30-35 (Kingston,1974)

Primary settlement

-

May-July

Stage-specific habitats

Salinities < 15 are lethal after 4 days

Thread-drifters acclimated after 1 week

Fisheries management

+ Eurihaline

Thread-drifters

juveniles

♀ ♂

Salinity Optimum: 25 (Verdelhos et al. 2015)

Salinity Optimum: 30-35 (Kingston,1974)

Primary settlement

-

May-July

Salinities < 15 are lethal after 4 days

Thread-drifters acclimate after 1 week BUT growth at 15

+ Eurihaline

Salinity stress has any

long-term effects?

Long-Term Experimental Design:

Thread-drifters ≈ 2mm

3 replicates x 4 Salinity treatments: 5, 15, 25 and 35

2 Days

Spat reared at the laboratory Salinity 35

10 Months

Salinity ≈35

Growth: - End of estrés -5 days recovery -1 month recovery -10 month recovery Gametogenetic index

ab b

bc c

2 days stress: Slower growth at low salinities

ab b

bc c

2 days stress: Slower growth at low salinities

Irreversible damage at Salinity 5

a a

b

5 days recovery: Salinity 35 keeps advantage

a

a

a

5 days recovery: Salinity 35 keeps advantage

1 month to catch up with growth after the stress episode

Advanced

Gonad Restoration

Post-spawning

Ripe

Initial

Resting

10 months recovery:

Delay on gametogenesis for Salinity 15 ? Why??

χ 2 =39.59 p=0.0002

Martinez-Castro & Vazquez 2012

(March 2016)

a

b

a

Higher metabolic demand Related to gonad

restoration

Advanced

Gonad Restoration

Post-spawning

Ripe

Initial

Resting

10 months recovery:

Delay on gametogenesis for Salinity 15 ? Why??

χ 2 =39.59 p=0.0002

Martinez-Castro & Vazquez 2012

(March 2016)

Thread-drifters

juveniles

♀ ♂

-

- Salinities < 15 activate the “isolation reflex” and become lethal after 4 days of exposure.

- Salinity of 5 cause irreversible damage after 2 days

- Salinity <20 CR O2 consumption excretion

-Thread drifters acclimated after a week and are able to

catch up with growth in one month.

-Sedentary settlers already lost certain eurihalinaty

+ Eurihaline Gametogenesis ?

Growth

The results shown in this presentation have been obtained with financial support from the Spanish Ministerio de Economia y Competividad to the project MARISCO, and a posdoctoral grant from Xunta de Galicia.

Acknowledgements:

Estación de Ciencias Mariñas de Toralla

ECIMAT