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  • Habitat complexity in coral reefs:

    patterns of degradation and consequences

    for biodiversity

    Lorenzo Alvarez Filip

    Thesis submitted for the degree of Doctor of Philosophy

    University of East Anglia, UK

    October 2010

    © This copy of the thesis has been supplied on condition that anyone who consults it is

    understood to recognise that its copyright rests with the author and that no quotation

    from the thesis, nor any information derived there from, may be published without the

    author’s prior, written consent.

  • A mi familia, esta tesis no es más que el resultado

    del amor y apoyo que he recibido

    de ustedes a lo largo de mi vida

    A México, por sus colores, por su magia, por su gente

  • Nature is not fragile . . . what is fragile are the

    ecosystems services on which humans depend

    Levin, S.

  • i

    Contents

    Page

    Abstract

    ii

    Acknowledgements

    iii

    General Introduction

    1

    Chapter 1: Flattening of Caribbean coral reefs: region-wide declines in

    architectural complexity

    6

    Chapter 2: Region-wide temporal and spatial variation in Caribbean reef

    architecture: is coral cover the whole story?

    19

    Chapter 3: Drivers of region-wide declines in architectural complexity on

    Caribbean reefs

    31

    Chapter 4: Coral identity underpins reef complexity on Caribbean reefs

    45

    Chapter 5: Coral reef architectural complexity influences fish community

    and food web structure

    58

    Concluding remarks

    76

    References

    83

    Appendices

    Appendix I

    Appendix II

    Appendix III

    103

    105

    109

  • ii

    Abstract

    Habitat destruction and degradation are primary causes of loss of biodiversity and

    ecosystem services. In the marine realm, there is the overwhelming concern about the

    rates of decline of coral reefs, which sustain thousands of species and support millions

    of livelihoods. Although declines in reef-building corals have been reported across

    different regions of the world, the concomitant consequences for reef architectural

    complexity have not been quantified to date. This in part is because the true nature of

    the relationship between live coral cover and reef architecture has yet to be described in

    detail. In this thesis, I describe the patterns of change in architectural complexity and

    explore the relationships between reef complexity, coral cover and the identity of reef-

    building corals in the Caribbean, a region in which coral reefs are highly threatened and

    degraded.

    Using an extensive database of studies reporting coral cover and reef rugosity

    over the last 40 years, I provide region-wide analyses of changes in reef architectural

    complexity. The results show that reef complexity has declined non-linearly with near

    disappearance of the most complex reefs over the last 40 years. The loss of coral cover

    is directly followed by reductions in complexity with little time-lag, and that there is

    little correspondence between the overall rates of change in coral cover and reef

    architecture, probably due to spatial variation in coral composition on reefs. Major

    drivers of coral mortality, such as coral bleaching, do not immediately influence

    architectural complexity, instead hurricane impacts and enhanced bioerosion inside

    protected areas appear to be important drivers of the widespread loss of architecturally

    complex reefs in the Caribbean.

    Through detailed studies of coral reefs in Cozumel, Mexico, I then show that

    although reef architectural complexity increases with coral cover, the rate of increase is

    highly dependent on the identity of dominant corals, with important reef-building coral

    such as Montastrea providing the most complex reefs. that the most complex remaining

    reefs in Cozumel, particularly those dominated by robust Montastrea corals, support

    fish assemblages with higher mean trophic levels and larger abundances of small-bodied

    fishes. This highlights the importance of complex reefs for fish recruitment, and thus the

    need to protect and enhance complex reef structures in order to maintain reef fisheries

    and biodiversity in the Caribbean.

  • iii

    Acknowledgements

    Firstly and foremost, I would like to thank my supervisors for their guidance and

    enthusiasm in the course of this project. Jenny Gill has been instrumental in the

    planning of this project, but above all, I deeply appreciate the fact that she always had

    time to listen my problems, and generally amazed me with her facility to find easy and

    clever solutions. Nick Dulvy, introduced me to the world of „fancy‟ statistics, and his

    enthusiasm, and passion inspired me to do my best and always look beyond the scope of

    my results. Andrew Watkinson, committed many hours to discussing the specific details

    of my work, and often helped to identify interesting and relevant angles for further

    exploration. Isabelle Côté, although not my „official‟ supervisor, became increasingly

    involved in my work over the course of my thesis. She always provided suggestions that

    noticeable improved my research. - It was really an honour to work with such a great

    group of scientist.

    This thesis would not have been possible without the support of a great number of

    people that have contributed to my professional development throughout the last

    decade. I therefore also would like to thank many researchers and friends back in

    Mexico, with whom I gave my first steps towards this thesis. Particularly I am very

    grateful to my former supervisors, Enrique Lozano, Patricia Briones and Hector Reyes.

    Some of the data used in this thesis were collected by other scientists, to whom I owe a

    great debt of gratitude for all their work and help. Peter Edmunds (California State

    University Northridge), Michelle Paddack (Santa Barbara City College), Philip Molloy

    (University of British Columbia), Renata Goodridge and Hazel Oxenford (CARICOMP

    Barbados), Francisco Geraldes (Universidad Autónoma de Santo Domingo and

    CARICOMP) and Simon Pittman and the NOAA Biogeography Branch all generously

    contributed unpublished data for the first three analytical chapters. The data used in

    chapters four and five were collected by Roberto Hernandez Landa (Centro de

    Investigación y de Estudios Avanzados, Merida), Marines Millet Encalada (Parque

    Nacional Arrecifes de Cozumel) and myself.

  • iv

    I am also very grateful to the Parque Nacional Arrecifes de Cozumel and the Comisión

    Nacional de Áreas Naturales Protegidas of México, for providing permission and

    support to carry out part of this research inside the marine reserve. I especially would

    like to thank Marines Millet, Lalo Brito, Beto Landa, „El Toro‟ and „El Capy‟ for their

    help and friendship during field surveys in my dear island.

    I am very grateful to my friends of the „Interdisciplinary group for coral reef

    research‟(UEA) and E2O group (SFU) who provide important and enriching discussion

    about societal and ecological aspects of marine resources. Particularly I would like to

    thank Maria Uyarra, Rady Talaat, Johanna Forster, and Allison Perry in Norwich; and

    Maria Jose, Michelle Paddack, Phill Moloy, Jen Sunday, Emily Darling in Vancouver

    for their always useful advices. Most recently, the “Stranglelers” group and friends

    from the Cabbage office provide me a great intellectual environment.

    Friends at UEA made working there a great experience. In particular, I would like to

    thank Andres Bucio, Manolo Canto, Clemet Inkamba, Karla Alcantar, Jorge Vazquez,

    Karel Castro, Frida Güiza, Chomphoo Kaewprasert, Sue Palminteri for their friendship,

    encouragement and support. In Mexico and other cities in England Gaby Cruz, Iris

    Segura, Gerardo Rios, Diana Vazquez, Javier Santillán, Francisco Nettel, Karina

    Ramirez among many other friends always supported me despite the distance. Finally, I

    would like to thank Alba for being there with me, for brighten with her smile all the

    difficulties that I went through.

    This research was entirely funded by Mexico throughout the Consejo Nacional de

    Ciencia y Tecnología, CONACyT (scholarship 171864) and the Secretaria de

    Educación Publica (programa de becas complementarias a estudiantes en el

    extranjero).

  • 1

    General Introduction

    Global ecosystems are changing at an unprecedented rate, largely as a consequence of

    several human-induced drivers of change (Pimm et al. 1995; Vitousek et al. 1997; Sala

    et al. 2000; Hoekstra et al. 2005). Although