Mollusc Biodiversity, Fisheries and Their Relations to Climatic and Physical-Chemical

Conditions

*Corresponding: sor.ratha006@mail.com

24th July 2017

Ratha Sor1,2*, Young-Seuk Park3, Pengbun Ngor2 and Sovan Lek2

1*Department of Biology, Royal University of Phnom Penh, Cambodia2 Laboratoire Evolution & Diversité Biologique, University of Toulouse – UPS III, France

3Department of Life and Nanopharmaceutical Sciences and Department of Biology, Kyung Hee

University, Seoul 130-701, Republic of Korea.

Molluscs in Ecosystems

2

• A key component of freshwater ecosystems

• Contributing to bioturbation and filtration in freshwater systems

(Bogan, 2008; Covich et al., 1999; Palmer et al., 1997).

(Chea et al., 2017)

Mollusc biodiversity in the Mekong

3Gupta (2009)

• The Lower Mekong Basin (LMB) is a hotspot zone supporting a high diversity of molluscs (Bogan, 2008; Strong et al., 2008).

• ~121 species of gastropods• ~39 species of bivalves • At least 111 gastropods and 5

bivalves are endemic

~4,350 km from the source

• In the Tonle Sap Lake and River systems, molluscs are the second fisheryproduction after fishes (Rainboth, 1996)

What lies ahead?

4

1) To investigate investigated mollusc biodiversity and community patterns in response to physical-chemical, land cover and climatic variables in the Lower Mekong Basin

2) To assesse the landed mollusc fisheries around the Tonle Sap Lake

Scarce number of studies on mollusc diversity, patterns, fisheries and their responses to environmental gradients in the LMB(Quang et al. 2013)

Study area and samples

5

• 109 mollusc samples (63 sites) from 2004 to 2008, every March

• Independent variables:

• Physical-chemical variables• Land cover types• Climatic variables (bioclim)

• Landed fisheries: 3 species • Corbicula moreletiana• Pila ampullaceal • P. polita

• Daily landed biomass

Biodiversity and Community Patterns

7

• 98 mollusc taxa, the most common species include• Corbicula tenuis (65.1%), Stenothyra koratensis holosculpta

(28.6%), C. lamarckiana (26.8%), and Limnoperna siamensis(23.8%)

• The most abundance species were: C. leviuscula (17.3%), L. siamensis (12.6%), C. tenuis (11.9%), C. lamarckiana (8.5%).

• 21 families, the most common families include • Unionidae (17.6%)• Corbiculidae (13.7%)• Viviparidae (11.8%)• Pomatiopsidae (10.8%) and Stenothyridae (10.8%).

Biodiversity and Community Patterns

8

Cluster Dendrogram

He

igh

t

1 3 2

01

23

45

6• 3 clusters could be distinguished

Legend

N

Cluster 1

Cluster 2

Cluster 3

Major River

0 120 240 Km

Biodiversity and Community Patterns

Cluster 1 Cluster 2 Cluster 3

Legend

N

Cluster 1

Cluster 2

Cluster 3

Major River

0 120 240 Km

Functional Community Patterns

40 3955

6 6

4

54 5542

Cl.1 Cl.2 Cl.3

Scraper (%)

Gatherer-Collector (%)

Filter-Collector (%)

-0.5 0.0 0.5 1.0

-0.5

0.0

0.5

RDA1 (13%)

RD

A2

(1

0%

)

-10

1

SAWRD

EC

TEM

Urb

Evg.all

Agr

Reg

bio1

bio3

bio5bio7

bio15

bio17

22

22

3

1

2 2

1

2

2

2

2

11 1

2

2

2

11

2

2

2

2

2

11

1 1

22

2

3

2

2

2

2

1

2

2

2

2

1

2

22

2

2

33

33

3

333

333

2

1

3

Cor.ten

Cor.sp

Afr.cla

Lim.siaCor.lam Lim.sp

Sin.har

Cor.spCor.bau

Cor.morAng.spPac.sp

Hub.spSte.sp

Ste.kor

Relationship between communities with environment

Relationship between communities with environment

Physical-chemical Land covers

Climatic

0.03 0.02

0.10

0.010.05

0.01

Residuals = 0.79

Landed mollusc fisheries around the Tonle Sap

Species

Total

biomass

Total values

in dollar ($)*

C. moreletiana 6,436,439 369,805

P. polita 1,511,280 781,025

P. ampullacea 381,899 218,053

-1.0 -0.5 0.0 0.5 1.0

-0.5

0.0

0.5

1.0

NMDS1

NM

DS

2

Cmor.inc

Pamp.inc

Ppol. mass

02

03

04

05

09

10

11

12

wl.m

mean.t

mean.pre

0.9 0 0.9

00

.9

01Ppol.inc

Cmor.massPamp.mass

Landed mollusc fisheries around the Tonle Sap

Summary and implications

• Mollusc diversity increases from the upstream to the down stream

• Climatic and water quality variable are the determinants, driving the different organization of

• Filter-collectors are more diverse in the downstream

• Mollusc fisheries contributes to food security, employment and economy, especially for the poorer segment of the society (Balian et al., 2008)

diversity

+

Acknowledgements