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National Library Bibliothèque nationale du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. me Wellington Ottawa ON K1 A ON4 Ottawa ON KIA ON4 Canada Canada Our aie No<re ra'fdmvu The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant a la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or seil reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfichelfilm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve Ia propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts f?om it Ni Ia thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author' s ou autrement reproduits sans son permission. autorisation. Multiple a pproaches for assessing mangrove use and mangrove change following anthropogenic and natural disturbances: A case study of the Mexican Pacifie. by John M. Kovacs Graduate Program in Geography Submitted in partial fiilfilIrnent of the requirements for the degree of Doctor of Philosophy Faculty of Graduate Studies The University of Western Ontario London, Ontario November, 1999 O John M.Kovacs 2000 ABSTRACT The purpose of this investigation was to assess the mfulness of several different and independent approaches for identifying and evaluating agents of mangrove disturbances. The methods employed included interviews with local fishermen, transect data analysis and the examination of remotely sensed Unagery fiom satellites. The results fiom the study indicate that the mangrove forest of the Teacapk Agua Brava lagoon system of Mexico has expenenced considerable degradation since the early 1970s and that this condition does not appear to be abating. By comparing Landsat TM scenes, it was calculated that approximately 18 % and 33 % of this forest was either dead or in poor condition in 1986 and 1999 respectively. Moreover, these data aiso suggest that the major agent of the changes was the opening of an artificial channel in 1972, the Cuautla canal, that Iinks the Iargest areas of the systern directly to the Pacific Ocean. It is postulated that increased salinity, associated with the canal, nias adversely affected the mangrove forest, particularly Laguncularia racernosa, which was adapted to a more fieshwater dorninated-environment. From interviews with the local elderly fishemen, it was found that the inhabitants of this system are very knowledgeable of the mangrove forests, employing them quite regularly for a variety of local uses. Moreover, the accounts of these fishermen coincide with the early forest changes identified from the satellite analysis and Mersuggesr a modification in the fauna associated with the opening of the canal. [n addition to the canal, the local inhabitants also perceived Hm-icane Rosa in1994 as a major dkurbance to the mangroves of this region. Consequently, a polytomouis logistic regression mode1 was developed Eorn the measurernents of 1390 trees in the hurricane impacted areas. The results from this mode1 reveal various relationships among the species of mangrove, the diarneter at breast height, the stem condition, and the outcome vegetation condition following such an event. Keywords: coastal wetland: mangrove use; mangrove degradation; aaificial channe1; hmicane; interviews; fishermen; logistic regression; rernote sensing; Pacific Coast; Mexico. CO-AUTHORSHIP The following thesis contains material that has been submitted to a journal as a CO-authoredmanuscript. The transect data ernployed in Chapter 4 were collected with the assistance of Manuel Blanco-Correa and Francisco Flores-Verdugo. Both individuais were also instrumental in coordinating the field logistics and transportation to the transect sites. John Kovacs preformed al1 encoding, analysis and interpretation of these data as well as the write-up. DEDICATION To my loving wife Christine ACKNOWLEDGEMENTS First and foremost 1would Iike to thank my advisor, Dr. Jacek Malczewski, for his endless motivation. support humour and sound advice. Dr. Malczewski was always available on short notice, aiways willing to review my work and provided invaluable guidance through the publication process. I must also extend my sincere gratitude to Drs. Jeffrey Hopband Jinfei Wang, my advisory cornmittee, who both critically reviewed manuscnpts, were constant sources of encouragement and never complained at the endless requests for letters of reference. Special thanks to Dr. Raphael Moreno (postdoc. 2 995-96) for persuading me to work in Mexico and for providing names of potential contacts in Mexico. 1would aiso like to acknowledge Dr. Rajulton Fernando (sociology) who reviewed the analysis and interpretation of my statistical tests. The numerous grad students in the Department of Geography must also be thanked for making the experience enjoyable. h particuiar, I would like to express my gratefdness to my colleagues, Rich Pyrce, Qiaofeng Zhang, Xi Xi Lu, Yiping Li, Scott St. George, Dan Walters and Steven Gyimah. In Mexico, my sincere gratitude is extended to the towns of Antonio R. Laureles, El Pescadero, El Roblito, Francisco Villa, Pahar de Cuautla and Pencos for their goodwill and cooperation in this investigation. I would also like to thanic the Universidad Autonoma de Nayarit (UAN) for providing the facilities and the Secretaria del Medio Ambiente, Recursos Naturales y Pesca (SEMARNAP) of Nayarit for their logistic support during this study. In particular, I wodd like to thank Professors Rosa, Luis Bojorquez and Rayrnundo Arvizu at UAN and the Tecuala field detachment of SEMARNAP- Nayarit. Veterinarian Jose Romero-Villaniel (SEMARNAP) was an excellent interpreter, guide, liaison and expert on local fauna and local naines. 1am especially thankfil to Professor Manuel Blanco-Correa (UAN) and Dr. Francisco Flores-Verdugo (Universidad Nacional Autonoma de Mexico). Both Manuel and Francisco shared in the extreme difficulties, danger and excitement of the various treks through the mud laden mangrove forests. I will never forget our encounters with boa constrictors, fire ants, termites, scorpions and quick sinking mud! 1 am indebted to the generosity of Manuel Blanco's entire farnily, Ricardo, Hector and Terra, who welcomed me into their home for four months and made al1 efforts to rnake my stay as enjoyable as possible. Manuel's farnily exposed me to a very rich Mexican culture that 1 constantly miss. The editors and nurnerous reviewers of the Jounials Landscape and Urban Planning,Land Degradation & DeveZopment and Journal of Coastal Research offered important comments and suggestions that strengthened the qudity of this thesis. This endeavor could never have rnaterialized without the fuiancial support of doctoral grmts provided by the International Development und Research Centre of Canada and the Canada Centre for Rernote Sensing. Finally, 1 would like to extend gratitude to my entire family including my in-laws, new and old, for their encouragement and long time support of my academic st~dies.MY parents, Frank and June, have, throughout the years, always been a source of pride and inspiration. No words cm express my special thanks to my wife who suppoaed me fiom day one and enlightened me to the more important things in life. vii TABLE OF CONTENTS CERTIFICATE OF EXAMINATION CO-AUTHORSHIP DEDICATION ACKNOWLEDGEMENTS TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF APPENDlCES CHAPTER I INTRODUCTION 1.1 Research question 1.2 Select methodologies and thesis format 1.3 General background on mangrove disturbances 1.3.1 Natural disturbances 1-3 -2 C hannelization and impoundrnent 1.3.3 Industrial and urban development I .3.4 Oil spills 1-3 -5 Mangrove exploitation 1-3 -6 Agricdture 1.3.7 Shrimp farming 1.3.8 Other nearshore modifications associated with the intensification of fisheries 1.4 Literature cited CHAPTER 2 ASSESSING MANGROVE USE AT THE LOCAL SCALE 2.1 Introduction 2.2 Study area 2.3 Methodology 2.4 Results and discussion 2.4.1 Identification and relative abundance of mangroves 2.4.2 Potential uses for mangrove species 2.4.3 Actual uses of mangrove wood 2-44 Preference for different environments 2.5 Surnrnary and conclusions 2.6 Literature cited CWTER3 PERCEPTIONS OF ENVIRONMENTAL CHANGE IN A TROPICAL COASTAL WETLAND Introduction Study area 3.2.1 The Teacapb-Agua Brava Lagoon 3 -2.2 Previous research on the mangrove system Methodology Results 3.4.1 Changes in physical aspects of the environment 3 -4.2 Change in mangrove composition 3.4.3 Identification and evaluation of agents of mangrove disturbance 3.4.4 Current threats to the mangroves 3 -4.5 Change in faunal composition of mangroves Discussion Conclusion Literature cited CWTER4 A LOGISTIC REGRESSION MODEL OF I3JRkIcAN-E IMPACTS INA h/IANGROVE FOREST OF THE MEXICAN PACIFIC Introduction Study area Methodology Results and discussion 4.4.1 General observations 4.4.2 Logistic regession mode1 4.4.3 Seedling densities and potential for uprooted Laguncularia Conclusion Literature cited CHAPTER 5 MAPPMG DISTURBANCES IN A MANGROVE FOREST USJNG MULTI-DATE LANDSAT TM IMAGERY 5.1 Introduction 5.2 Study area 5.2.1 The Teacaph-Agua Brava lagoon system . 5.22 Pevious reports of mangrove forest decline 5.3 Methodology 5.3.1 Image selection and pre-processing 5.3 2 Digital change detection 5-3 -2.1 Creating the threshold masks 5 -3-2.2 Classification procedure 5.4 Results 5.4.1 Overall changes in mangrove cover fiom 1986 to 1999 5.4.2 Verification and regional considerations 5.5 Discussion and conciusion 5 -6 Literature cited CHAPTER 6 GENERAL DISCUSSION AND CONCLUSION APPENDICES LIST OF TABLES Table 2- 1 Evaluation by fisherrnen of the potential of mangroves for the following purposes (5=excellent, 4=good, 3=average, 2=poor, 1-very poor). Table 2.2 Fishermen's evaluation of the magnitude of mangrove use for the following Local items (4=very often, 3=often, S=sometimes, l=seldom, O=never).