This presentation is dedicated to the memory of Dr. Miguel F. Lavin (CICESE), who was a

great researcher and a good friend.

May he rest in peace!

(February 1951- February 2014)

EFFECTS OF THE OMZ ON THE DISTRIBUTION OF FISH LARVAE:

UNEXPECTED RESULTS….

Laura Sánchez Velasco (lsvelasc@gmail.com)

Emilio Beier, Víctor Godínez, †Miguel F.

Susan Davis (estudiante doctoral) Adalberto Tamayo (estudiante maestría)

Index 1-Definitions

Larval fish habitatHypoxia and anoxia

2-Previous studies of the working group

3-Manuscript derived from a doctoral thesis

Three-dimensional distribution of larval fish habitats in the shallow oxygen minimum zone in the eastern tropical Pacific Ocean off Mexico.

S.M. Davies, L. Sánchez-Velasco, E. Beier, V. M. Godínez and D. Barton

4-Advances of masters thesis

Distribution and larval feeding of Bregmaceros bathymaster in the region of confluence between the Gulf of California and the Mexican Pacific.

Adalberto Tamayo Corona

Fish larvae

Mesopelagic species

The larvae of fish species from different environments co-exist mainly in the first 200 m depth.

200 m

Sea surface

Epipelagic species

2000 m

Bathypelagic species

Coastal demersal species

Distribution gradients fish larvae result in different larval habitats throughout the water column (eg. Surface mixed layer, thermocline).

- LARVAL FISH HABITATS

Deep dem

ersal species

2- HYPOXIC AND ANOXIC

Hypoxic water from ~ 1 mL/L to ~0.2 mL/L

Anoxic water < ~0.2 mL/L

The upper limit of the shallow oxygen minimum zone ~0.2 mL/L

Three-dimensional distribution of fish larvae in a cyclonic eddy in the Gulf of California during the summer

L. Sánchez-Velasco, M.F. Lavín, S.P.A. Jiménez-Rosenberg, V.M. Godínez, E. Santamaría-del-Angel, D.U. Hernández-Becerril

Deep Sea Research Part I 75 (2013) 39–51

3- Previous studies of the working group

A system of four mesoscale eddies was detected using chlorophyll a images. The cruise was focused on the cyclonic eddy CE-1.

Tran

sect

acr

oss

the

axis

of

the

Gul

f

Geostrophic velocities (cm / seg) detected that the total width of the eddy was 140

km (A05-A19) with a depth of 470 m.

Black line, zero speed; Red, input current; and blue, output current.

Role of circulation scales and water mass distributions on larval fish habitats in the Eastern Tropical Pacific off Mexico

Cristina A. León-Chávez, Emilio Beier, Laura Sánchez-Velasco, Eric Desmond Barton, Victor M. Godínez

The most abundant larvae in the area off Cabo Corrientes were the Bregamaceros bathymaster, mesopelagic species

- Manuscript derived from a doctoral thesis

Three-dimensional distribution of larval fish habitats in the shallow oxygen minimum zone in

the eastern tropical Pacific Ocean off Mexico.

S.M. Davies, L. Sánchez-Velasco, E. Beier, V. M. Godínez and D. Barton

Deep Sea Research Part I, in revision 2014

Based on biological antecedents of the OMZs and the ETP off Mexico, we expect to find a larval fish habitat in

the oxygenic waters with maximum zooplankton biomass and the highest larval fish abundance; and a larval fish habitat in the hypoxic waters with lowest

larval abundant. In addition, we expect to find high abundance of larvae of B. bathysmaster off Cabo Corrientes, but it is difficult

to predict their vertical distribution and preferential habitat.

Hypothesis

The aim of this study is to analyze the three-dimensional distribution of the larval fish habitats,

from the upper limit of the shallow OMZ to surface, in the ETP off Mexico during February 2010. The

distribution of larval fish habitats will described in function of the environmental gradients, with

emphasis in the dissolved oxygen.

Objetive

Study area was from the entrance of the Gulf of California to off Cabo Corrientes

(14–27 February 2010)..

Satellite images are from Aqua/MODIS (4x4km)

46 sampling stations (46 physical and 20 biological)

CTD data with dissolved oxygen and fluorescence sensors were obtained.

Zooplankton hauls were taken with an Opening-Closing conical net (505 µm) at 3 depth strata in the water column:

Thermocline

Sea surface

~ upper limit of the shallow oxygen minimum zone (~0.2 mL/L)

GC IM CC

CC ocean

GC IM CC ocean

GC IM CC ocean

A total of 5,089 fish larvae, most of them

in preflexion stage (79%), were collected.

They were included in 61 taxa belonging to

31 families of coastal demersal and

epipelagic and mesopelagic fish. Of these,

51 taxa were identified to species level, 9

to genus level and one to family level.

Three significantly different (ANOSIM: R=0.5, P<0.05) larval fish habitats could be identified

A B

GC CCIM

CC ocean

GC IM CC ocean

Habitats   Gulf of California Pacific Tropical Mixed Layer Oxygen Minimum

Family Taxa X %F %S H X %F %S H X %F %S H

Myctophidae Diogenichthys laternatus 29 47 1 C         106 24   D

Phosychthyidae Vinciguerria lucetia 28 47 7 C 198 100 50 D 226 72 2 D

Myctophidae Benthosema panamense 26 29 42 D 29 10 1 C

Bregmacerotidae Bregmaceros bathymaster 22 29 8 D 2644 100 97 D

Engraulidae Anchoa sp. 18 29 42 D

Myctophidae Diaphus pacificus 17 18 4 D 80 34 1 C

Eleotridae Eleotris picta 17 12 1 O 23 14 1 C

Chiasmodontidae Chiasmodon niger 11 18 1 D

Synodontidae Synodus lucioceps 9 35 2 C

Nomeidae Cubiceps pauciradiatus 7 18 1 C 19 37 0,8 C

Labridae Xyrichthys mundiceps 6 18 1 C

Scombridae Auxis spp. 14 25 1 C

Bregmacerotidae Bregmaceros sp. 4 18 0,6 C

Eleotridae Dormitator latifrons 34 17 1 C

Carangidae Caranx caballus 19 10 1 C

Bothidae Bothus sp. 13 25 1 C

Number of taxa     36       12       44    

Number of sampling stations 8 36 12

Abundance of larvae /10m2 per station 73 33 117

Abundance of larvae /10m2 per taxon 2 3 3

Mean zooplankton biomass (mL/1000m3) 422 526 68

X, mean larval abundance per station; %F, percentage frequency of occurrence; %S, Similarity percentage; Hierarchy by Olmstead-Tukey, C(Constant), D(Dominant), O(occasional)    

Canonical Correspondence Analysis (CCA)

Three larval fish habitats were defined statistically: i) A habitat dominated by Anchoa spp. larvae (epipelagic species), constrained to the oxygenated surface layer (>3.5 mL/L) on the thermocline (~60 m depth) in the southern Gulf; and separated from the Tropical Pacific habitat, by a salinity front.

ii) A Tropical Pacific habitat, dominated by Vinciguerria lucetia larvae (mesopelagic species), located through the water column, but with the highest abundance in the oxygenated upper layer above the thermocline.

Summary

iii) A third habitat defined mostly below the thermocline in hypoxic (<1mL/L; ~70 m depth) and anoxic (<0.2 mL/L; ~80 m depth) water off Cabo Corrientes. This subsurface hypoxic habitat had the highest species richness and larval abundance, with domain of Bregmaceros bathymaster, an endemic mesopelagic species; which was an unexpected result.

This may be associated to the raise of the upper limit of the shallow oxygen minimum zone near to the coast, result of the costal upwelling characteristics of this region.

We can hypothesizer that the vertical expansion of the OMZs to the surface did not cause dramatic effects, at least, in the total larval abundance in regions with coastal upwelling.

Project SEP-CONACyT 105922 “Asociaciones de larvas de peces, hábitat trófico y su relación con la estructura física en giros del

Golfo de California” Proyect SEP-CONACyT “Investigaciones oceanográficas del

sistema frontal de BCS” Project SIP-IPN 20130252 “Oceanografía y larvas de peces como

indicadores del sistema pelágico del Golfo de California”

Laboratory of Circulation and Coastal Dispersion (CIRCOS-CICESE)

Dr. Miguel F. Lavín Peregrina

A boat crew Francisco de Ulloa CICESE

ACKNOWLEDGMENTS