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Legacy effects of marine larval development for a diadromous fish species, Mike Hickford [et al.]

Legacy effects of marine larval development for a diadromous fish species, Mike Hickford [et al.]

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Phylogeography of Eleotris fusca (Teleostei:

Gobioidei: Eleotridae) in the Indo-Pacific

area reveals a cryptic species in the Indian

Ocean

Marion Mennesson

1



∗ 1



Biologie des Organismes et Ecosyst`emes Aquatiques (UMR BOREA 7208) – Mus´eum National

d’Histoire Naturelle (MNHN) – 43 rue Cuvier, CP26 75005 Paris, France



Indo-Pacific insular freshwater systems are mainly dominated by amphidromous species.

Eleotris fusca is a widespread one, its life cycle is characterised by a marine pelagic larval phase

allowing the species to disperse in the ocean and then to recruit to remote island rivers. In

the present study, the population structure of E. fusca over its Indo-Pacific distribution range

(Western Indian Ocean to French Polynesia, Pacific Ocean) was evaluated. We analysed a section of mitochondrial COI of 557 individuals sampled from 28 islands to visualise the population

structure. Haplotypes diversity was high (0.458 ≤ Hd ≤ 1) and nucleotide diversity was low

(0.001 ≤ π ≤ 0.02), and two distinct genetic groups appeared, one in the Indian Ocean and the

other in the Pacific Ocean (F ST mean = 0.901; 5.2% average divergence). Given these results,

complete mitogenomes (mtDNA) were sequenced and combined with the nuclear Rhodopsin

(Rh) gene. The two phylogenetic trees based on each analysis showed the same genetic pattern: two different groups belonging to the Indian and the Pacific oceans (6.6% and 1.6% of

divergence for mtDNA and Rh gene respectively) which, supported species level differentiation.

These analyses revealed the presence of two sister species confounded until present under the

name of Eleotris fusca. One of them is cryptic and endemic of the Indian Ocean and the other

one is the true E. fusca, which keeps, nevertheless, its status of widespread species.

Keywords: Eleotris, Indo-Pacific area, cryptic species, complete mitogenome, nuclear gene







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Spatial distribution, trophic ecology and

growth of three tropical eel species

(Anguilla marmorata, A. megastoma and A.

obscura) living in sympatry in Gaua island

(Vanuatu Archipelago)

Anthony Acou∗ 1 , Cory Garot-Adrian 1 , Alexandre Carpentier 2 , Marion

Mennesson 3 , Christine Dupuy 4 , Philippe Keith † 3 , G´erard Marquet 5 ,

Donna Kalfatak 6 , Laure Virag 1 , Eric Feunteun 1

1



Museum National d’Histoire Naturelle (MNHN) – Mus´ee National d’Histoire Naturelle - MNHN

(France) – Station Marine de Dinard, 38 rue du port blanc 35800 Dinard, France

2

Universit´e de Rennes 1 – EA GTUBE, Universit´e de Rennes 1 – Campus de Beaulieu, 35042 Rennes

cedex,, France

3

Museum National d’Histoire Naturelle (MNHN) – Mus´ee National d’Histoire Naturelle - MNHN

(France) – 43 rue Cuvier F-75231 Paris cedex, France

4

Littoral Environnement et Soci´et´es UMR 7266 (LIENs UMR7266) – Universit´e de La Rochelle – 2 rue

Olympe de Gouges, 17042 La Rochelle Cedex 01, France

5

Museum National d’Histoire Naturelle (MNHN) – Mus´ee National d’Histoire Naturelle - MNHN

(France) – 57 rue Cuvier F-75231 Paris cedex, France

6

Department of Environment and Conservation – Private mail bag 063, Port Vila, Vanuatu



At least 4 species of anguillid eels are present in the western south Pacific: giant mottled

eel A. marmorata, Polynesian long-finned eel A. megastoma, Australian long-finned eel A. reinhardtii and Polynesian short-finned A. obscura. Their freshwater distribution overlap in the

archipelago of Vanuatu but little is known about their life history, spatial organization and

trophic ecology. A comprehensive sampling using electrofishing, snorkeling, hand nets or traditional fishing tool with hook was conducted from 29th October to 5th November 2014 in Gaua

Island (Banks Islands, Vanuatu) in order to describe species occurrence of eel species and collect information on their ecology and notably their diet. Using stable isotopic analysis, trophic

networks were described in three contrasted habitats: (1) the volcanic Letas lake localized upstream the 120 m high Siri Falls (standing waters > 10 m deep), (2) its outflowing Solomul

river complex and tributaries (running waters, < 2 m deep) and (3) the Kaska creek, an independent temporary stream with shallow (< 1 m) turbid waters closed to the sea. Based on

molecular genetic analyses (CO1 barcoding), 4 species were detected among the 28 specimens

collected. The dominant species was A. marmorata constituting 64.3% of the catches, then A.

obscura and A. megastoma with 21.4% and 10.7% respectively. Unexpectedly, one specimen of

A. interioris was collected in the Letas lake, which constitutes the first occurrence of the species

in the Vanuatu Archipelago. A obscura was dominant in the Kaska Creek and A. megastoma







Corresponding author: anthony.acou@mnhn.fr

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in Letas Lake, while A. marmorata was present in all habitats. The growth pattern estimated

from otoliths was not very clear due to low samples but seems to depend on species rather than

a site effect. Stable isotopic analysis confirmed that eel species, whatever the habitat, are toppredator. However, when they co-exist, eel species seems to share different preys, which suggest

that resource partitioning may play a role in regulating the spatial organization of eel species in

tropical river systems.



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Spatio-temporal variability of leptocephali

trophic networks in the South Pacific Ocean

Aur´elie Dessier 1 , Bastien Bourillon 1 , Eric Feunteun ∗ 2 , Anthony Acou 2 ,

Alexandre Carpentier 3 , Michael J. Miller 4 , Mari Kuroki 5 , Katsumi

Tsukamoto 4 , Tsuguo Otake 5 , Christine Dupuy 6

1



LIttoral ENvironnement et Soci´et´es - UMR 7266 (LIENSs) – Universit´e de La Rochelle, Centre

National de la Recherche Scientifique : UMR7266 – Bˆatiment ILE 2, rue Olympe de Gouges 17 000 La

Rochelle, France

2

Biologie des Organismes et Ecosyst`emes Aquatiques (BOREA) – Museum National d’Histoire

Naturelle, Universit´e Pierre et Marie Curie - Paris 6 : UM95, Centre National de la Recherche

Scientifique : UMR7208 – 7, rue Cuvier, CP 32, 75231 Paris Cedex 05, France

3

EA 7462 – Universit´e de Rennes I – EA 7462, Campus de Beaulieu, Bˆat 25, Av. du G´en´eral Leclerc,

35042 Rennes Cedex, France

4

College of Bioresource Science, Nihon University – Fujisawa, Kanagawa 2520880, Japan

5

Graduate School of Agricultural and Life Sciences, The University of Tokyo – Bunkyo, Tokyo

1138657, Japan

6

LIttoral ENvironnement et Soci´et´es [La Rochelle] (LIENSs) – CNRS : UMR7266, Universit´e de La

Rochelle – Bˆ

atiment Marie Curie Avenue Michel Cr´epeau 17 042 La Rochelle cx1 - Bˆatiment ILE 2, rue

Olympe de Gouges 17 000 La Rochelle, France



Anguilliform eel larvae are ubiquitously distributed in the surface layers of intertropical

oceans. The mystery of their diet is seemingly being progressively unveiled, although a number

of materials are known to be consumed as particulate organic matter that include zooplankton

fecal pellets, discarded appendicularian houses, or marine snow, along with the DNA barcoding

signatures being found of many types of organisms. In the context of two research cruises conducted by the R/V Hakuho Maru in the South Pacific in 2013 (February, austral summer, 5 million km2 ) and 2016 (August to September, austral winter, 12 million km2 ), the trophic network of

leptocephali was described using carbon and nitrogen stable isotopes. Particulate organic matter

(POM) was sampled using Niskin bottles at layers from the surface to the maximum fluorescence

depth. Zooplankton (copepods, siphonophores, annelids etc.), and leptocephali from 5 families

(Anguillidae, Congridae, Muraenidae, Nemichthyidae and Serrivomeridae) were collected using

an Isaacs-Kidd Midwater Trawl. In 2016, additional sampling of micro-zooplankton was performed using a NORPAC net to target smaller zooplankton species. An unprecedented sampling

effort covered 34 stations along 2 longitudinal transects (171◦E, 170◦W) between 7-30◦S in 2013

and 62 stations in 4 longitudinal transects (175◦E, 170◦W, 155◦W, 140◦W) between 5-25◦S in

2016. The sampling transects were set across 4 major currents of the region that are the South

Equatorial Countercurrent, the Fiji Countercurrent, the South Equatorial Current and the South

Pacific Subtropical Countercurrent. A strong latitudinal pattern of nitrogen isotope ratios (less

obvious in carbon) were observed in most sampled zones in 2016 whereas a longitudinal effect

was less pronounced. Based on leptocephali isotope ratios, three trophic networks (TN, north,

intermediate and south) were highlighted in austral winter. The main variation within them





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was linked to nitrogen isotope ratios. A relative stability in carbon and nitrogen isotopic ratios

of POM was observed in these 3 TN. Temporally, nitrogen and carbon isotope ratios were more

homogenous in austral summer than in austral winter with leptocephali trophic networks that

were less distinct. These results are discussed in terms of hydrographic/meteorological contexts

and previous information about leptocephali diets.



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