[Comparing the Abundance of Balanus Glandula at Different Shore Levels on the Exposed Shore]

By

[Name of Faculty]

[Name of School or Department]

ACKNOWLEDGEMENT

I would take this opportunity to thank my research supervisor, family and friends for their support and guidance without which this research would not have been possible.

DECLARATION

I, [type your full first names and surname here], declare that the contents of this dissertation/thesis represent my own unaided work, and that the dissertation/thesis has not previously been submitted for academic examination towards any qualification. Furthermore, it represents my own opinions and not necessarily those of the University.

ABSTRACT3

Keywords3

CHAPTER 1: INTRODUCTION4

CHAPTER 2: METHODS6

2.1. Spiral' trap6

2.2. Coned' trap6

2.3. Field sites7

2.4. Comparison of regular vs. spiral traps at Kinkell8

2.5. Comparison of spiral vs. coned traps at Fife Ness and Tentsmuir9

2.6. Larval settlement9

2.7. Mesoscale geographic analysis of the S. balanoides supply/settlement relationship10

2.8. Wind data10

2.9. Larval counts and estimates of larval supply10

2.10. Data analysis11

CHAPTER 3: RESULTS13

3.1. Comparison of regular vs. spiral traps at Kinkell13

3.2. Comparison of spiral vs. coned traps at Fife Ness and Tentsmuir15

3.3. Mesoscale geographic analysis of the S. balanoides supply/settlement relationship19

CHAPTER 4: DISCUSSION22

4.1. Trap selectivity22

4.2. Onshore/offshore winds, transport of larvae and effects on intertidal supply22

4.3. Incidence of faecal S. balanoides cyprids23

4.4. Settlement choice and failure23

4.5. Spiral vs. coned traps: choice of cone and the supply/settlement relationship24

CHAPTER 5: CONCLUSION25

REFERENCES26

ABSTRACT

Planktonic cyprid larvae of the intertidal barnacle, Semibalanus balanoides (L.) and the infralittoral/sublittoralBalanus crenatus Brug., are readily captured in small, chambered, passive traps deployed on rocky shores. Several structural developments of a previous trap design improved urea (killing solution) retention and capture of cyprids of both species. The design adopted for assessment of the larval supply/settlement relationship of the focal species, S. balanoides, included additional internal baffles and the replacement of the cylindrical trap opening with a coned aperture. Three sizes of cone aperture area were compared, with the intermediate size (1 cm2) being optimal for measuring larval supply over the full range of wave action on local shores. Most daily catches included larvae that were recognizable as having been dead before they were trapped, and had recently passed through the guts of grazing limpets (Patella vulgata L.). One site showed that ~32% of trapped S. balanoides were so-called 'faecal' cyprids. An inability to distinguish these in trap samples would lead to a significant over-estimation of larval supply. Preliminary data indicated that S.balanoides larval supply to the intertidal is enhanced by onshore winds (or perhaps increased wave turbulence), whereas B. crenatus supply was positively correlated with offshore winds (or decreased turbulence). A clear 'supply/settlement' relationship for S. balanoides at six sites along ~40 km of coastline was derived from 1 cm2 coned trap catches and daily counts of settlement on ceramic tiles. There were no instances of disproportionately high settlement in relation to larval supply, but at five sites there were days when settlement apparently failed. The identification and explanation of settlement success and failure is fundamental to understanding the importance of larval supply in structuring marine benthic populations and communities.

Keywords

Balanus crenatus; 

Cyprid; 

Larval supply; 

Panel; 

Semibalanus balanoides; 

Settlement; 

Tile; 

Trap

CHAPTER 1: INTRODUCTION

The importance of larval supply as a likely driver of rocky shore population/community dynamics, and as a determinant of adult species abundances, has long been recognized ...