Presentation by

Syaza Hani binti Jamaludin (P76797)

For STAL 6013

Danwei Huang, Peter A. Todd, James R. Guest

OVERVIEW

IntroductionPurpose of

Study Materials

and Methods

Results Reference

Movement and Aggregation in the Fluted Giant Clam

INTRODUCTION

Inhabit shallow waters of tropical Indo-Pacific coral reefs

Traditional food source

Locomotion is crucial for the survival of bivalves

Bivalve may orientate and move according to several abiotic factors (light, gravity)

Aggregation between conspecifics is one of thepossible outcomes of movement and is a majordeterminant of survival in animals

Movement and Aggregation in the Fluted Giant Clam

Movement and Aggregation in the Fluted Giant Clam

INTRODUCTION

Possible proximate causes of this behavior:

Clumping could be a result of individuals moving randomly, stopping when groups are formed

Gregariousness among individuals, especially chemotic attraction

PURPOSE OF STUDY

Aggregation of clams occur in

aquarium tanks and in

the field

Clam movement is affected by byssal

attachment

Clams are attracted to one another and exhibit

positive intraspecific chemotaxis

Movement and Aggregation in the Fluted Giant Clam

MATERIALS AND METHODS

1. General experimental procedures

Study location : Marine aquaculture facility in TMSI (Tropical Marine Science Institute) on St John’s Island, Singapore

Duration : July 2005 to March 2006

Test organism : Juvenile (23-63mm) from spawning in March 2004

Movement and Aggregation in the Fluted Giant Clam

MATERIALS AND METHODS

2. Clam movement and phototaxis

Movement and Aggregation in the Fluted Giant Clam

Mark initial position. Data collected in 7 days. Pearson Chi-square was applied

Acrylic sheets in the control treatment &

PVC ring were removed slowly

Placing PVC ring around

each animal

MATERIALS AND METHODS

Movement and Aggregation in the Fluted Giant Clam

Three light treatments were set up using wide-spectrum SYLVANIA F36/GRO fluorescent tube : 1. Light from one direction2. Light from two opposite directions, A and B3. No light

MATERIALS AND METHODS

3. Aggregation in Giant Clam

Movement and Aggregation in the Fluted Giant Clam

Analysing distribution by 30 x 30 cm

Cartesian coordinates of the clams’ final positions were recorded after three days

Microsoft Excel 2003, ANOVA, SNK (Student-Newman-Keuls) test

Laboratory work

MATERIALS AND METHODS

3. Aggregation in Giant Clam

Movement and Aggregation in the Fluted Giant Clam

Field experiment 80x80cm enclosures on the reef flat of St John’s Island

using SCUBA

Similar to aquarium experiment

ANOVA

MATERIALS AND METHODS

4. Attraction and chemotaxis among giant clam

I. Live clam

II. Fouled clam shell

III. Foul-free clam shell

IV. Random inanimate object

V. None (empty ring)

Movement and Aggregation in the Fluted Giant Clam

MATERIALS AND METHODS

5. Data analyses

Pearson Chi-square test

T-test

ANOVA

ANCOVA

SNK test

Movement and Aggregation in the Fluted Giant Clam

RESULTS

1. Clam movement and phototaxis

• High significant associaton between type of movement and presence of attachment

• 30.8% of bysallyattached clams moved. 26.6% rotation and 4.2% translation

Movement and Aggregation in the Fluted Giant Clam

2. Aggregation in giant clam• SNK comparisons

showed that clams were more aggregated in the live clam run than both random walk

, mean clumpy was higher in the live clam run than the stimulations

Movement and Aggregation in the Fluted Giant Clam

RESULTS

3. Attraction and chemotaxis among giant clams• The proportion of clams moving

toward the live clam target (80%) was greater than movement away from it (10%) & occur more than with other object

• For , 1 clam moved away from the effluent of conspecifics with majority (80%) moving toward water emerging from the source container

• Control treatment: similar numbers moving in both directions (towards 33.3%, away 36.7%, center 30%)

Movement and Aggregation in the Fluted Giant Clam

RESULTS

DISCUSSIONMovement & aggregation

do occur Combination of

movement (foot action & valve contraction) could be a consequence of reduction in foot size relative to the enlarging shell

Locomotive behavior in bivalve to enhance their survival

Ability to move determines its fitness

Movement and Aggregation in the Fluted Giant Clam

No significant association between direction of light source & clam movement pattern

Clumping appears to be more pronounced in the field than in tanks

Greater movement ability in younger because decrease of foot size to shell-weight ratio as clam size increase

Movement and Aggregation in the Fluted Giant Clam

DISCUSSION

Movement and Aggregation in the Fluted Giant Clam