Field Guide to Mangrove Identification and

Community Structure Analysis

! 2 Lebata-Ramos SEAFDEC/AQD

ON THE COVER: Mixed species of mangroves in Subic Bay, Zambales, Philippines [PHOTO by MJH Lebata-Ramos] ISBN 978-971-9931-02-7 Published by: Southeast Asian Fisheries Development Center Aquaculture Department Tigbauan, Iloilo, Philippines Copyright © 2013 Southeast Asian Fisheries Development Center Aquaculture Department Tigbauan, Iloilo, Philippines All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher Photographs, lay-out and graphics by: MJH Lebata-Ramos, except for those with blue borders

from Primavera et al. (2004) For comments SEAFDEC Aquaculture Department and inquiries Tigbauan, Iloilo 5021, Philippines Tel (63-33) 511 9172 Fax (63-33) 511 8709 Email aqdchief@seafdec.org.ph AQD website www.seafdec.org.ph

! 3 Lebata-Ramos SEAFDEC/AQD

I. Introduction

Mangroves may refer to the constituent plants of tropical intertidal forest communities or to the whole community itself. They are common on mudflats and banks of tropical and subtropical rivers and coastlines, existing at the boundary of land and water and receiving nutrients from both environments. They possess morphological, physiological, biochemical and reproductive adaptations that enable them to grow in the unstable and harsh tropic intertidal environment. Morphological and ecophysiological characteristics and adaptations of mangroves include aerial roots, viviparous embryos, tidal dispersal of propagules, rapid rates of canopy production, frequent absence of an understorey, absence of growth rings, wood with narrow, densely distributed vessels, highly efficient nutrient retention mechanisms, and the ability to cope with salt and to maintain water and carbon balance.

Mangroves are distributed circumtropically. Their distribution is determined by latitude, temperature (air temperature >20ºC; water temperature ≥24ºC) and coastal aridity. Rainfall also influences mangrove distribution, largely by its effect on salinity. Mangroves are almost exclusively tropical and are confined between 30ºN and 30ºS latitudes. On a global scale, the essential environmental prerequisites for mangrove development are temperature, mud substrate, protection, salt water, tidal range, ocean currents, and shallow shores.

The mangrove ecosystem is a valuable economic and ecological resource. Mangroves are an important source of plant and wood products. Mangroves protect shorelines during storms and typhoons by absorbing wave energy and reducing water velocity. Their root system assists in binding sediment particles, thereby facilitating accretion and preventing coastal erosion. Riverine mangroves reduce water velocity by adding flood storage capacity, thus mitigating flooding. Mangroves maintain estuarine water quality. Suspended matter, nutrients and heavy metals are reduced by the mangrove root system. The sediment and nutrient retention function of mangroves provide waters suitable for seagrass and coral reef development. Mangroves also function as a nursery habitat. As a habitat for a range of organisms, both from the terrestrial and aquatic environments, mangroves themselves are unique systems with very high biodiversity.

Approximately 73 species of plants, belonging to 28 genera and 21 families, are recognized throughout the world as being mangroves. The most diverse mangrove forests are found in Southeast Asia. Of these 73 species, 37 are found in the Philippines. This Field Guide to Mangrove Identification and Community Structure Analysis provides a key and images of plants and plant parts for identifying Philippine mangrove species. This guide was designed for field use by researchers, government agencies, NGOs, academicians and students who are actively involve in mangrove research. Aside from the identification key, the guide includes a definition of terms used, species codes used when identifying mangroves in the field, instructions on how to lay-out quadrats and conduct mangrove community structure analysis and the equations needed for the analysis.