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ASSESSMENT OF THE DISTRIBUTION, ABUNDANCE AND CARBON STOCKS IN SEAGRASS MEADOWS WITHIN EASTERN AND WESTERN CREEKS OF GAZI BAY, KENYA GABRIEL AKOKO JUMA A Thesis Submitted to the Graduate School in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science in Environmental Science of Chuka University CHUKA UNIVERSITY SEPTEMBER 2019 DECLARATION AND RECOMMENDATIONS ii COPYRIGHT ©2019 All rights reserved. No part of this Thesis may be reproduced or transmitted in any form or by any means of photocopying, recording or any information storage or retrieval system, without prior permission in writing from the author or Chuka University. iii DEDICATION I dedicate this work to my parents, Mr. Agustinus Juma and Mrs. Rosemary Atieno who were always very proud of me. iv ACKNOWLEDGEMENT The journey to the development of this thesis has been momentous and challenging but its success is one of the greatest milestones in my academic life. I accord my utmost appreciation to the people who nurtured the dream and passion in me, supported and guided me to see the fulfillment of this academic endeavor. To a greater extent, I am grateful to Prof. Adiel Magana of Chuka University for his mentorship and supervision. The inspiration, in-depth scrutiny of my work and guidance he gave were of great significance. Special appreciation is also accorded to Dr. James Kairo of Kenya Marine and Fisheries Research Institute (KMFRI), Mombasa for his supervision and support during my field work and thesis development. I sincerely thank the panel members of Chuka University at the various developmental stages of this thesis, particularly, the Director of Chuka University Board of Post Graduate Studies, Dr. Moses Muraya and Chair of Chuka University Department of Environmental Studies and Resource Development, Dr. Lemmy Muriuki for the necessary support and insights. Their suggestions and professional comments helped me to maintain focus leading to successful finishing of this work. In a special way, I wish to acknowledge the support of the Field Assistants during data collection in Gazi. Special thanks is to KMFRI team including, Tom Kisiengo, Laitani Suleiman, Peter Musembi, Derrick Omollo, Charles Muthama, George Onduso and Julia Oluoch for assisting in the field sampling and laboratory sample processing. I am also grateful to the community members Hassan Omar and Hassan Amiri for offering boat transportation during the field work. Finally, I am grateful to the National Commission for Science Technology and Innovation (NACOSTI) for the issuance of the permit (NACOSTI/P/18/52699/24288), to undertake this study. This M.Sc. thesis was funded by Punguza Hewa Kaa: Partners in Carbon Project, awarded to KMFRI by Newton Fund for Institutional Links Grant, to whom am very grateful. v ABSTRACT Seagrass meadows are one of the most important blue carbon ecosystems within the seascape environment providing both ecological and economic benefits. They act as breeding and feeding grounds for fish and other organisms; perform carbon sequestration, nutrient cycling and other ecosystem services. Through their carbon capture and storage ability, seagrass can be incorporated in carbon offset schemes. However, they are highly degraded from both anthropogenic and natural factors. Carbon stocks assessment is required in understanding dynamics of seagrass meadows. In Gazi Bay, Kenya, carbon storage in the seagrass meadows has been determined in the open waters of the Bay. The present study aimed at contributing to carbon dynamics of Gazi bay by assessing the distribution, abundance and carbon storage in seagrass within the mangrove fringed creeks. The objectives included assessing distribution and abundance of seagrass in the creeks, determining above and below ground seagrass biomass and comparing sediment carbon stocks between vegetated and un-vegetated sites. Stratified random sampling strategy was used in collecting data within 80 square plots of 0.25m by 0.25m. Five species formation viz; Thalassia hemprichii, Cymodocea rotundata, Cymodocea serrulata, Enhalus acoroides, and Thalassidendron ciliatum were encountered as either single or mixed stand. A total of 480 samples were collected for sediment and biomass determination in the laboratory. The results showed a higher seagrass diversity in the Eastern creek, (H = 1.71), than Western creek, (H = 1.67). There was also a significant difference in the total biomass between the creeks (t= -8.44, df. = 53, p < 0.0001) and among species (F = 14.6, df = 79, p < 0.0001) with a mean of 7.25 ± 4.2 Mg C ha-1, (range: 4.1 - 12.9 Mg C ha-1). Sediment carbon varied between species within the 1.2 km2 creeks area; with a range from 97.6 to 302.4 Mg C ha-1, (mean: 183.4 ± 100.5 Mg C ha-1). This is lower than 236 ± 24 Mg C ha-1, reported in the open bay but within the global range. In all the species, vegetated areas showed significantly higher carbon values than the un-vegetated sites (t = 12.02 p < 0.0001). Based on this study, the total seagrass carbon stocks can be estimated at 21,118.8 Mg C. Using the IPCCC emission value of 7.9 tonnes of C ha-1, values for organic soils for wetlands, conservation of seagrass in these two mangrove fringed creeks will prevent emission of 2,682.13 Mg 1 of CO2 equivalent yr- to the atmosphere. The avoided emission could be bundled with the existing offset scheme in the bay involving mangroves. Inclusion of seagrass in carbon offset scheme has a long term benefits of climate, community livelihood and biodiversity conservation. vi TABLE OF CONTENTS DECLARATION AND RECOMMENDATION ...................................................... ii DEDICATION............................................................................................................. iv ACKNOWLEDGEMENT ........................................................................................... v ABSTRACT ................................................................................................................. vi TABLE OF CONTENTS .......................................................................................... vii LIST OF FIGURES ..................................................................................................... x LIST OF TABLES ...................................................................................................... xi LIST OF ABBREVIATIONS AND ACRONYMS ................................................. xii CHAPTER ONE: INTRODUCTION ........................................................................ 1 1.1 Background of the Study ..................................................................................... 1 1.2 Statement of the Problem ..................................................................................... 4 1.3 Objectives ............................................................................................................ 5 1.3.1 Broad Objective ............................................................................................ 5 1.3.2 Specific Objectives ....................................................................................... 5 1.4 Research Hypotheses ........................................................................................... 5 1.5 Significance of the Study ..................................................................................... 5 1.6 Scope of the Study ............................................................................................... 6 1.7 Limitation of the Study ........................................................................................ 6 1.8 Operational Definition of Terms .......................................................................... 7 CHAPTER TWO: LITERATURE REVIEW ........................................................... 9 2.1 Overview of Seagrass Ecology, Species Composition and Adaptations ............. 9 2.1.1 Ecosystem Services of Seagrass ................................................................. 10 2.1.2 Threats to Seagrass ..................................................................................... 12 2.1.3 Management Practices ................................................................................ 13 2.2 Seagrass Species Distribution and Abundance .................................................. 14 2.2.1 Seagrass Abundance ................................................................................... 14 2.2.2. Seagrass Distribution ................................................................................. 15 2.2.3 Seagrass Composition and Distribution in Kenya ...................................... 20 2.3 Above Ground and Below Ground Carbon Stocks in Seagrass Meadows ........ 22 2.4 Seagrass Sediment Organic Carbon ................................................................... 25 vii 2.4.1 Effects of Habitat Features on Long-term Corg Storage in Soils within the Seagrass Meadows ............................................................................... 26 2.5 Policy gaps and Implications ............................................................................. 34 2.6 Theoretical Framework of the Study ................................................................. 34 2.7 Conceptual Framework of the Study ................................................................. 34 CHAPTER THREE: MATERIALS AND METHODS ......................................... 37 3.1 The Study Area .................................................................................................