i

ii
 MODULE 8

SEAGRASS: ASSESSMENT & MONITORING

iii
COPYRIGHT

iv
 TABLE OF CONTENTS

Foreword ...........................................................................................................................................................ix
Preface................................................................................................................................................................xi
Acknowledgements .......................................................................................................................................xiii
About the Module .......................................................................................................................................... xv
Objectives .................................................................................................................................................... xv
Learning Outcomes.................................................................................................................................... xv
Acronyms ........................................................................................................................................................ xvi
1. Introduction ...............................................................................................................................................1
1.1 Physiology and habit.......................................................................................................................1
1.2 Ecological functions and services ................................................................................................3
1.3 Threats to seagrass ecosystems ..................................................................................................8
2. Seagrass Species Identification............................................................................................................ 12
2.1 Seagrass species diversity .......................................................................................................... 12
2.2 Seagrass species reported in the Philippines ......................................................................... 15
3. Assessing and Monitoring Seagrass Ecosystems in the Philippines ........................................... 25
3.1 Ecological Indicators ................................................................................................................... 26
3.2 Preassessment preparation ....................................................................................................... 29
3.3 Seagrass assessment .................................................................................................................... 32
3.4 Field Assessment Protocol ........................................................................................................ 35
3.6 Standardization of Collected Seagrass Data .......................................................................... 43
4. Procedures For Data Analysis and Interpretation ........................................................................ 44
4.1 Data Recording ............................................................................................................................ 44
4.2 Data Processing ........................................................................................................................... 44
5. Applications to Ecosystem Management and Conservation ...................................................... 49
References ....................................................................................................................................................... 52
Appendix.......................................................................................................................................................... 56
Visual Guide for Estimating Seagrass Percent cover................................................................................. 56

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 LIST OF TABLES

Table 1. Annual average global value of ecosystem services* ................................................................5

Table 2. Coastal environmental problems with the most severe impacts on seagrasses in the
Philippines. ...................................................................................................................................... 10
Table 3. Seagrass species in the world and in the Philippines. ............................................................ 12
Table 4. Potential biological and ecological variables in assessing and monitoring seagrass
ecosystem. ...................................................................................................................................... 27
Table 5. General sampling approaches and the corresponding data acquired. ............................... 27
Table 6. Various methods for assessing and monitoring seagrass and the corresponding
biological data output of multisectoral field personnel........................................................ 28
Table 7. General substrate description. ................................................................................................... 37
Table 8. Sample seagrass datasheet. .......................................................................................................... 38
Table 9. Sample data sheet with field data from seagrass assessment/monitoring. ........................ 40
Table 10. Sample tabulated output of a seagrass assessment activity. .............................................. 48
Table 11. Pressure-state-response model for managing seagrass ecosystems. ............................... 50

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 LIST OF ILLUSTRATIONS

Figure 1. Distinguishing features between marine algae or seaweeds and seagrasses. .....................1
Figure 2. Parts of a seagrass ramet. ..............................................................................................................2
Figure 3. Monospecific and multispecies seagrass beds. ..........................................................................3
Figure 4. Ecosystem services from seagrass meadows ............................................................................4
Figure 5. Seagrass ecosystems supporting a diverse community of marine organisms. ...................6
Figure 6. Key processes of seagrass ecosystem carbon sequestration and storage. .........................8
Figure 7. Threats to seagrass ecosystems. ..................................................................................................9
Figure 8. Global distribution of seagrass species richness. ................................................................... 13
Figure 9. Architectural and structural features of various seagrass genera. ..................................... 15
Figure 10. Various seagrass species as seen in their habitat. (continued) ......................................... 23
Figure 11. Overview of the desktop mapping process using CoRVA method. ............................... 30
Figure 12. Materials and equipment for seagrass assessment. ............................................................. 31
Figure 13. Transect-quadrat sampling method. ...................................................................................... 34
Figure 14. Seagrass assessment and monitoring using transect-quadrat method. .......................... 34
Figure 15. Guide for estimating epiphyte cover on seagrass leaves. .................................................. 43
Figure 16. Sample Excel® data template for seagrass assessment. .................................................... 45
Figure 17. Sample graphical data of seagrass cover and total density. ............................................... 46
Figure 18. Sample bar charts of different seagrass species................................................................... 46

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viii
FOREWORD

ix
x
PREFACE

xi
xii
ACKNOWLEDGEMENTS

xiii
xiv
 ABOUT THE MODULE

OBJECTIVES

LEARNING OUTCOMES

xv
 ACRONYMS

WGS World Geodetic System

UP University of the Philippines
UNEP United Nations Environment Programme
SCUB A Self Contained Underwater Breathing Apparatus
CoRVA Coral Reef Visualization and Assessment
LGU Local Government Unit
IUCN International Union for Conservation of Nature
Biodiversity Research and Information Network Group – Hub of People and the
B RING- HOP E
Environment
GSRM Global Seagrass Research Methods
GP S Global Positioning System
GIS Geographic Information System
Coastal Assessment for Rehabilitation Enhancement: Capacity Development and
CA RE- CaDRES
Resiliency of Ecosystems
DO Dissolved Oxygen
DM Margalef’s index
DENR Department of Environment and Natural Resources
CO2 Carbon dioxide
BMB Biodiversity Management Bureau

xvi
 1. INTRODUCTION

1.1 PHYSIOLOGY AND HABIT

NON-FLOWERING FLOWERING
Do not have underground root system, but instead Has below-ground parts (i.e., rhizomes and roots)
uses “holdfast” for anchoring
Sexual reproduction via spores Sexual reproduction via flowering, pollination,
and fertilization
Asexual reproduction via vegetative propagation Asexual reproduction via vegetative propagation, clonal
Presence of leaf sheath to protect developing leaves

Figure 1. Distinguishing features between marine algae or seaweeds and

seagrasses.

1
Figure 2. Parts of a seagrass ramet.

2
 Figure 3. Monospecific and multispecies seagrass beds.
A single Thalassia hemprichii stands on an intertidal flat (left) and mixed bed of up to seven
species (right).

1.2 ECOLOGICAL FUNCTIONS AND SERVICES

3
Figure 4. Ecosystem services from seagrass meadows
Source: Adapted from Ramesh et al. (2019)

4
Table 1. Annual average global value of ecosystem services*

AREA TOTAL VALUE PER HECTARE

BIOME
(HECTARES ⨉ 106) (1994 USD PER HECTARE PER YEAR)
Marine 36,302 577
Open ocean 33,200 252
Coastal 3,102 4.052
Estuaries 180 22,832
Seagrass/Algal beds 200 19,004
(34,000**)
Coral reefs 62 6,075
Shelf 2,660 1,610
Terrestrial 15,323 804
Forest 4,855 969
Tropical 1,900 2,007
Temperate/Boreal 2,955 302
Grass/Rangelands 3,898 232
Wetlands 330 14,785
Tidal marsh/Mangroves 165 9,990
Swamps/Floodplains 165 19,580
Lakes/Rivers 200 8,498
Cropland 1,400 92

Note: *17 ecosystem services and functions are used in this module: gas regulation, climate regulation, disturbance regulation,
water regulation, water supply, erosion and sediment retention, soil formation, nutrient cycling, waste treatment,
pollination, biological control, refugia, food production, raw materials, genetic resources, recreation, and cultural services.

Sources: Adapted from Costanza et al. (1997, 2014); **Short et al. (2011)

1.2.1 Habitat

5
 Figure 5. Seagrass ecosystems supporting a diverse community of marine
organisms.

1.2.2 Producers

1.2.3 Livelihood

6
1.2.4 Filter and Buffer

1.2.5 Pollutant Sink

1.2.6 Carbon Sequestration and Storage

7
 Figure 6. Key processes of seagrass ecosystem carbon sequestration and storage.
The blue arrows indicate the process of transporting atmospheric or dissolved material, the red
arrows show how particulates are transported, and the purple arrow indicates
rhizome growth and meadow expansion.
Source: Adapted from Duarte et al. (2013)

1.3 THREATS TO SEAGRASS ECOSYSTEMS

8
Figure 7. Threats to seagrass ecosystems.
Source: UNEP (2020)

9
Table 2. Coastal environmental problems with the most severe impacts on
seagrasses in the Philippines.
URGENCY
THREATS
IMMEDIATE SHORT-TERM LONG-TERM

Habitat destruction*** 1 1 1
***
Sewage pollution 2 2 3
Industrial pollution*** 3 3 2
Fisheries overexploitation*** 4 4 6
***
Siltation/ sedimentation 5 5 4
**
Oil pollution 6 6 8
*
Hazardous waste 7 7 7
**
Agricultural pollution 8 8 5
*
Red tide 9 9 11
*
Coastal erosion 10 10 10
*
Natural hazards
11 12 12
(e.g., catastrophic weather events)
Sea-level rise* 12 11 9
Notes: (1) Asterisks indicate the severity of impact: *** severe impact, ** moderate impact, * slight or no impact
(2) The issues are ranked in order of priority and urgency:
Immediate = within the next five years
Short term = within the next five years
Long-term = within the next ten years or more

Source: Fortes (2013)

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1.3.3 Overfishing

1.3.4 Global Climate Change

11
 2. SEAGRASS SPECIES IDENTIFICATION

2.1 SEAGRASS SPECIES DIVERSITY

Table 3. Seagrass species in the world and in the Philippines.

FAMILY AND GENERA GENERAL NO. OF SPECIES NO. OF SPECIES

(WITH TRUE MARINE SPECIES) DISTRIBUTION WORLDWIDE IN THE PHILIPPINES

Hydrocharitaceae
Enhalus Strictly tropical 1 (1) 1
Enhalus acoroides
Thalassia Mainly tropical 2 (2) 1
Thalassia hemprichii
Halophila Temperate and tropical 15 (20) 9
Halophila beccarii
Halophila decipiens
Halophila gaudichaudii
Halophila major
Halophila minor
Halophila ovalis
Halophila ovata
Halophila spinulosa
Halophila sp.1
Halophila sp.2
Cymodoceaceae
Cymodocea Mainly tropical 4 (4) 2
Cymodocea rotundata
Cymodocea serrulata
Halodule Mainly tropical 7 (6) 2
Halodule pinifolia
Halodule uninervis

Table 3 (continued)

12
 (continued) Table 3
FAMILY AND GENERA GENERAL NO. OF SPECIES NO. OF SPECIES
(WITH TRUE MARINE SPECIES) DISTRIBUTION WORLDWIDE IN THE PHILIPPINES

Syringodium Mainly tropical 2 (2) 1

Syringodium isoetifolium
Thalassodendron Strictly tropical 2 (3) 1
Thalassodendron ciliatum
Amphibolis Strictly temperate 2 (2) 0
Posidoniaceae
Posidonia Strictly temperate 9 (8) 0
Zosteraceae
Zostera (subgenus) Mainly temperate 4 (13*) 0
Zosterella (subgenus) Temperate and tropical 7 0
Phyllospadix Temperate 5 0
Heterozostera Temperate 4 0
Ruppiaceae
Ruppia Temperate and tropical 1 (10) 1
Ruppia maritima
Zannicheliaceae
Lepilaena Strictly temperate 1 (6) 0
TOTAL 66 (77) 19
Note: *Include Heterozostera species since the International Plant Names Index does not accept this genus

Sources: Global data is from den Hartog and Kuo (2006);

Numbers in parenthesis are from Kuo et al. (2018)
Local data are from Fortes (1989, 2013) and Fortes et al. (2018)

Figure 8. Global distribution of seagrass species richness.

The numbers 1–6 indicate the bioregions, including the tropical Indo-Pacific where the
Philippines is located.
Source: Short et al. (2007)

13
14
 Figure 9. Architectural and structural features of various seagrass genera.
Source: Modified from McKenzie (2008)

2.2 SEAGRASS SPECIES REPORTED IN THE PHILIPPINES

Halodule pinifolia (Hp)

• Has very fine and thin leaves with rounded tip, which
can reach up to 20 centimeters (cm) in length
• Single, central vein splits into two at the leaf tip
• Rhizome is usually pale with black leaf scars
• Found in intertidal sand banks

15
Halodule uninervis (Hu)
• Trident leaf tip (imagine “batman”-like shape)
• Single, central, longitudinal vein
• Rhizome is usually pale in color with black leaf scars
• Generally, has a larger/broader leaf blade than
Halodule pinifolia
• Found in shallow, intertidal sand or mud banks
• Among the preferred food of dugong

Cymodocea rotundata (Cr)

• Flat, strap-like leaves, 2–4 millimeter (mm) in width
• Round, smooth leaf tips
• Looks clean and smooth rhizome
• Scars are visible on leaf sheaths and form a continuous
ring around the stem
• Found in shallow reef flats

Cymodocea serrulata (Cs)

• Strap-like leaves with wide leaf blade, 5–9 mm in width
• Serrated leaf-tips
• Highly visible triangular leaf sheath with a narrow base
• Leaf scars on stem do not form a continuous ring
• Found in shallow, subtidal reef flats and sand banks

16
Enhalus acoroides (Ea)
• Long, ribbon-like leaves that can be over 1 m in
length, depending on water depth
• Leaves are thick and strong with in-rolled leaf margins
• Thick rhizome with long, black bristles and cord-like
roots
• Found in shallow, intertidal sand or mud banks, usually
adjacent to mangrove forests

Thalassia hemprichii (Th)

• Hook, broad, and curved leaves that are 10–40
centimeters (cm) in length
• Visible short black bars of tannin cells on leaf blade
• Thick rhizome with scars
• Commonly found in shallow sandy reef flats

Syringodium isoetifolium (Si)

• Leaves have a cylindrical cross-section that ends in
pointed tips (terete in shape), approximately 7–30 cm
in length
• Leaves feel round when touched, like a thin cylinder,
straw, or spaghetti
• Found in shallow intertidal reef and sand banks

17
Thalassodendron ciliatum (Tc)
• Cluster of ribbon-like leaves at the end of an erect
rhizome
• Round, serrated leaf tips
• Hard, woody rhizome with scars
• Branching roots
• Typically found in rocky areas and reef crests

Halophila ovalis (Ho)

• Simple, oval-shaped leaves in opposite pairs
• No hairs on leaves
• Has eight or more cross veins
• One of the early-colonizing species
• Found at intertidal to subtidal depths
• Among the preferred food of dugong

Halophila spinulosa (Hs)

• Fern-like with erect shoots, up to 15 cm in length
• Compound leaves arranged in opposite pairs
• Found at subtidal depths at around 10 m

18
Halophila decipiens (Hd)
• Small, oval leaves, 1.0–2.5 cm in length (usually longer
than wide)
• Leaves have hairs on dorsal and ventral sides and with
6–8 cross veins
• Found at subtidal depths of approximately 10 m

Halophila minor (Hmi)

• Simple, oval-shaped paired leaves
• Less than eight pairs of cross-veins
• Leaf sheath are wedge-like in shape
• Found in shallow, intertidal sand flats

Halophila beccarii (Hb)

• First reported in Parañaque on the southeast fringes
of Manila Bay; but recent reports have hinted a
possible local “extirpation” (Liao and Geraldino 2020)
• Leaves are arranged in pseudo-whorls of 4–10 leaves,
giving rise to a rosette arrangement
• Petiole are well-differentiated and sheathed
• Leaf blades are well-differentiated and either linear,
elliptical, or lanceolate, with a width of less than 4 mm
and length of 6–11 m
• Has a narrow, restricted depth range right at the
intertidal zone

19
Halophila gaudichaudii (Hg)
• H. ovata is a synonym of this species
• First reported in Manila Bay, and a museum specimen
has been collected from Argao, Cebu
• Very similar to H. minor except for the distance
between intramarginal veins and lamina margin of
approximately 0.4–0.6 mm wide and with a ratio ca.
1: 4.0–8.3
• Cross veins are 4–8, arising at angles of 30°–45°,
unbranched
• Distance between adjacent cross veins is
approximately 1.75 mm wide
• Grows with H. ovalis, H. minor, and H. pinifolia in
shallow waters (5–7 m) or with H. decipiens in deeper
waters (24 m)

Halophila major (Hma)

• H. major are morphologically similar to H. ovalis;
both species normally have a distinct ovate to elliptic
lamina and branching cross veins
• H. major usually has a larger leaf and lamina than
H. ovalis, with 18–22 cross veins and ratio of 20–25:1
for the distance between the intramarginal veins and
lamina margin: half of lamina width
• Flowering period is from June to September and
fruiting period is in August and September
• H. major has a narrower distribution range than
H. ovalis
• H. major occurs as small patches or mixed with
H. ovalis and/or H. minor as well as with other tropical
species (e.g., Halodule spp., Cymodocea spp.,
S. isoetifolium, or T. hemprichii) in the shallow water of
coral sands.

20
 Halophila tricostata (Ht)
• Has erect shoots at 8–18 cm in length
• Leaves have three veins
• With 2–3 leaves at each node that “whorl” around the
stem
• Found in subtidal depths (>10 m)
• Initially reported to have a restricted distribution and
considered endemic in Australia (Greenway 1979);
however, its presence in the species records of
Southeast Asia (Sabah, Malaysia, and the Philippines)
indicates its potential for long distance dispersal from
the Great Barrier Reef of Australia to the
Palawan/North Borneo ecoregion (Fortes et al. 2018)
and even Negros Occidental (Calumpong et al. 2010;
Tiongson 2012)

Ruppia maritima (Rm)

• Leaves are fine and thread-like with pointed tips
• Serrated leaf margins
• Flowers have long, spiral stalk
• Rhizomes are thin and delicate
• Has a wide salinity tolerance of 0–70 parts per
thousand
• Occurs in a variety of habitats, from low-salinity
ponds, coastal lagoons, mangroves, estuaries, marsh
pools, tidal rivers, fishponds to salt pans and
hypersaline areas

Source: The first 12 illustrations were adapted from the Seagrass-Watch manual and webpage

(http://www.seagrasswatch.org/id_seagrass.html); the last set of illustrations on

4 Halophila species, and Ruppia maritima were by Rebecca Yu.

21
22
Figure 10. Various seagrass species as seen in their habitat. (continued)
Sources: IUCN (2021); Fortes et al. (2018)

23
(continued) Figure 10

Ruppia maritima L.

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 3. ASSESSING AND MONITORING
SEAGRASS ECOSYSTEMS IN THE PHILIPPINES

•
•

•
•

25
3.1 ECOLOGICAL INDICATORS

26
Table 4. Potential biological and ecological variables in assessing and monitoring
seagrass ecosystem.

SAMPLING AND AMBIENT

BIOLOGICAL VARIABLES ECOLOGICAL VARIABLES
CONDITIONS

Seagrass percent (%) cover Water temperature (°C) Prevailing weather condition
Seagrass shoot count or density Tidal regime and water flow Date and time
(per area) Salinity Team members
Community structure or species Light availability Observations: Impact sources,
composition threats identified, human
Nutrients: nitrates and phosphates
Mean canopy height activities in the area, etc.
Dissolved oxygen
Epiphytic load and % cover
pH level and total alkalinity
Seaweed cover
Presence of macrofauna,
its identification, and
actual count

Table 5. General sampling approaches and the corresponding data acquired.

APPROACH DATA

Plant specimen collection

Type specimen (for preservation)

Development condition

Morphological condition

Plant material (e.g., individual shoot, biomass, organic carbon)

Seagrass mapping
Possible seagrass location and distribution using readily
(Seagrass-Watch method
available resources (Google Earth Pro) and straightforward,
by McKenzie et al. 2003;
detailed methods (like CoRVA), and/or remote sensing
CoRVA module)
Verified distribution and extent of seagrass area through
ground truthing

Helps in selecting sampling sites by providing a snapshot view

of the entire area

Information on seagrass mapping is very useful in sampling

design and in assessing and monitoring plans

Add up to a database of seagrass area and location in a GIS

Table 5 (continued)

27
 (continued) Table 5
APPROACH DATA

In-depth field surveys with the aid of Seagrass variables: species, composition, cover canopy height
snorkeling/skin diving gear or SCUBA (% cover and shoot density)
(i.e., English et al. 1997; Seagrass-Watch Associated algae (macroalgae, epiphyte)
survey methods by McKenzie et al. 2003; Associated macrofauna (invertebrates and fishes)
Short and Coles 2001)
Physicochemical factors (substrate, water quality)
Local community activities affecting the coastal habitats

In-situ photodocumentation Seagrass identification, species composition (per quadrat)

and % cover
Other notable marine organisms (epiphytes, algae,
invertebrates, and fishes)
Documentation and permanent records of the sampling area

Source: Modified from Short and Coles (2001)

Table 6. Various methods for assessing and monitoring seagrass and the
corresponding biological data output of multisectoral field personnel.

OUTPUT/INDICATORS
METHOD
ACADEME DENR LGU/COMMUNITY
Transect-quadrat Seagrass ID, species level Seagrass ID, species level Seagrass ID, genus level,
(Seagrass-Watch % cover and composition Percent seagrass cover or local names
protocol) and composition Percent seagrass cover
Species richness, dominance,
and diversity Canopy height and composition

Table 6 (continued)

28
 (continued) Table 6
OUTPUT/INDICATORS
METHOD
ACADEME DENR LGU/COMMUNITY
(cont’d) Canopy height Epiphyte % cover Associated organisms
Transect-quadrat Shoot density Associated invertebrates (algae, epiphytes, and
(Seagrass-Watch others)
Associated algal species Associated algae:
protocol)
observed and % cover species ID and
Associated invertebrates ID % cover
and count, species level
Epiphyte load and cover
Belt-transect Macroinvertebrates ID Macroinvertebrates ID Macroinvertebrates ID
(for macro- and count, species and count, genera level and count, local names
invertebrates) level
Monitoring Depends on study For coastal management, For coastal management,
frequency objectives, experimental at least twice a year at least twice a year
design, and funding (during dry and rainy (during dry and rainy
support season) season)
Notes: DENR = Department of Environment and Natural Resources
LGU = local government unit

Source: Modified from BMB (2017a)

3.2 PREASSESSMENT PREPARATION

29
3.2.1 Seagrass Mapping

Figure 11. Overview of the desktop mapping process using CoRVA method.

Seagrass Mapping Procedure

30
3.2.2 Sampling Materials and Equipment

1. 3 transect lines: 50–100 m fiberglass

measuring tapes (i.e., Tajima or Symron
brands)
2. Wooden/steel pegs, to keep lines in
place
3. Standard 50 ⨉ 50 cm quadrats (usually
prefabricated and can be made of
5-millimeter diameter stainless steel or
PVC pipes); a quadrat can be
subdivided into 25 smaller grids
4. Handheld GPS unit
5. Buoys or empty plastic water bottles as
markers
6. Measuring tape and ruler for canopy
height determination
7. Waterproof camera for documentation
and cover estimation
8. Magnifying glass for species ID
verification
9. Writing slates or underwater data
sheets with pencils
10. Snorkeling gear (mask, snorkel, fins,
and weights, if needed)
11. Boat (when necessary)
12. Personal protective equipment
(wetsuit or long sleeves and pants,
hats and booties)
13. Loggers (Hobo) and probes (Horiba,
YSI), if available, for water quality and
conditions

Figure 12. Materials and equipment for seagrass assessment.

31
3.3 SEAGRASS ASSESSMENT

3.3.1 Identifying Sampling Sites

3.3.1.1 Choosing seagrass assessment sites

32
3.3.1.2 Establishing seagrass monitoring sites

3.3.2 Transect-Quadrat Sampling Method

33
 Figure 13. Transect-quadrat sampling method.
Source: Modified from English et al. (1997); Short and Coles (2001); McKenzie et al. (2003)

3.3.3 Basic Team Competency

Figure 14. Seagrass assessment and monitoring using transect-quadrat method.

The intertidal flats are on the left side, whereas the subtidal and relatively deeper
areas are on the right.

34
3.4 FIELD ASSESSMENT PROTOCOL

3.4.1 Seagrass Mapping through Ground Truthing

35
3.4.2 Sampling Method

⨉ ⨉

BOX 1. TIPS IN SAMPLING

1. After laying the transect, try to minimize the disturbance to the sediment by
walking on one side of the transect (if the sediment is too shallow) and then
having the quadrat readings on another side. The team members should be
oriented to make it easier to obtain accurate observations or
photodocumentation when the sediment is disturbed.
2. When collecting samples in muddy areas during high tide, it is easier to sample
the area while swimming or using snorkeling gear (without fins) to avoid
disturbing the sediment.
3. It would be much easier to count shoots underwater with a SCUBA when the
water is relatively deep (over 1 m).
4. Bare patches should not be avoided when sampling seagrass meadows as
avoiding this may overestimate density. If transects are not used in sampling an
area, then random sampling or another method should be used, such as fixed-
point (McKenzie et al. 2003).
5. If the researcher is interested in determining seagrass biomass, then visual
estimation could be done using techniques similar to those developed in pasture
research. Mellors (1991) adopted this for seagrasses, albeit this method is not
applicable in areas with turbid water.

36
3.4.3 Visual Documentation

3.4.3.1 Description of sediment type

µm

Table 7. General substrate description.

SEDIMENT TYPE DESCRIPTION

Mud Smooth and sticky texture
Sand Rough, grainy texture
Clearly distinguishable particles
May be fine or coarse
Note color
Gravel or rocky Very coarse texture with some stones or rocks
Coral rubble Broken corals

37
Table 8. Sample seagrass datasheet.

Observer/s: Date:
Location: Site:
Transect no: Start time: End time:
GPS coordinates transect START & END: Weather condition
GPS Coordinates of meadow boundaries: Other observations
TOTAL SPECIES COVER (%) SPECIES SHOOT COUNTS ASSOCIATED MACROFAUNA PHOTO
QUADRAT
SUBSTRATE SEAGRASS ALGAE AND OTHER OF QUADRAT
NUMBER Ea Cr Cs Hu Hp Si Ho
% COVER (GENUS/SPECIES) OBSERVATIONS (NUMBER)

1 (0 m)

2 (5 m)

3 (10 m)

4 (15 m)

5 (20 m)

6 (25 m)

Table 8 (continued)

38
 (continued) Table 8
TOTAL SPECIES COVER (%) SPECIES SHOOT COUNTS ASSOCIATED MACROFAUNA PHOTO
QUADRAT
SUBSTRATE SEAGRASS ALGAE & OTHER OF QUADRAT
NUMBER Ea Cr Cs Hu Hp Si Ho
% COVER (GENUS/ SPECIES) OBSERVATIONS (NUMBER)

7 (30 m)

8 (35 m)

9 (40 m)

10 (45 m)

11 (50 m)
Note: Cr = Cymodocea rotundata Ho = Halophila ovalis Si = Syringodium isoetifolium
Cs = Cymodocea serrulata Hp = Halodule pinifolia
Ea = Enhalus acoroides Hu = Halodule uninervis

39
Table 9. Sample data sheet with field data from seagrass assessment/monitoring.

Observer/s: Nicolas & Nenette Date: 21 October 2018

Location: Sitio Uno, Brgy. Apatot, Caramay Site: Seagrass area located back of brgy hall and beside mangrove
Transect no: 1 Start time: 9:35 a.m. End time: 11:05 a.m.

GPS coordinates transect START & END: Waypoint 231 start/Waypoint 232 end Weather condition: Sunny and windy day
GPS Coordinates of meadow boundaries: Waypoints 242–261 Other observations:
% SPECIES COMPOSITION/ SEAGRASS SHOOT
TOTAL
COUNTS MACROFAUNA OBSERVED, PHOTO OF
QUADRAT SUBSTRATE SEAGRASS ALGAE
REMARKS QUADRAT
% COVER Th Cr Cs Ho Hp

0m Sandy-muddy 95 95 0 0 0 0 (3) sea star

150 0 0 0 0
5m Sandy-muddy 75 0 50 0 0 25 ✓
0 72 0 0 125

10 m Sandy-muddy 90 0 90 0 0 0 (5) sea star

0 135 0 0 0
15 m Sandy-muddy 85 0 85 0 0 0 (2) sea star

0 103 0 0 0

20 m Sandy-muddy 85 30 55 0 0 0
48 80 0 0 0

25 m Sandy-silt 20 0 20 0 0 0 Forams ✓
0 30 0 0 0

Table 9 (continued)

40
(continued) Table 9
% SPECIES COMPOSITION/
TOTAL MACROFAUNA
SEAGRASS SHOOT COUNTS PHOTO OF
QUADRAT SUBSTRATE SEAGRASS ALGAE OBSERVED,
QUADRAT
% COVER Th Cr Cs Ho Hp REMARKS

30 m Sandy-silt 60 40 5 10 5 0

0 7 0 0 0

35 m Sandy-silt 40 0 10 0 20 20 Padina Forams; (1) sea star

0 13 0 49 28
40 m Sandy-silt 20 3 2 0 10 5 (1) sea cucumber;
(1) shell

2 3 0 38 8
45 m Sandy-silt 15 0 0 0 10 5 Sargassum Forams ✓
41 7

50 m Sandy-silt 25 0 0 0 20 5 Sargassum Forams

0 0 0 50 6

41
3.5.3.2 Seagrass species composition

3.5.3.3 Seagrass percent cover

3.5.3.4 Seagrass shoot density

3.5.3.5 Associated algae present

3.5.3.6 Macrofauna and other features

42
 Figure 15. Guide for estimating epiphyte cover on seagrass leaves.
Source: Adapted from McKenzie et al. (2003)

3.6 STANDARDIZATION OF COLLECTED SEAGRASS DATA

43
 4. PROCEDURES FOR DATA ANALYSIS
AND INTERPRETATION

4.1 DATA RECORDING

4.2 DATA PROCESSING

4.2.1 Data Analysis

4.2.1.1 Percent cover

44
 Figure 16. Sample Excel® data template for seagrass assessment.
The generated pivot table summarizes the raw data in terms of average (or mean) and standard deviation (below).

45
 100

80

Seagrass cover (%)

60

40

20

0
Agutayan Rabor Melville
Sampling site
1400
Total shoot density (n sht m-2)

1200

1000

800

600

400

200

0
Agutayan Rabor Melville
Sampling site

Figure 17. Sample graphical data of seagrass cover and total density.
The top shows the data on percentage cover (%), whereas the bottom presents the number of
shoots per square meter at the three sampling sites.

800
Agutayan
700 Rabor
Shoot density (n sht m-2)

Melville
600

500

400

300

200

100

0
S. isoetifolium
T. hemprichii

C. rotundata
E. acoroides

H. uninervis

C. serrulata
H. pinifolia
H. ovalis

Seagrass species

Figure 18. Sample bar charts of different seagrass species.

The chart shows the mean shoot density (number of shoots per square meter) of each seagrass
species from the three sampling sites.

46
4.2.1.2 Density

4.2.1.3 Biodiversity indices and statistical indicators

Relative diversity.

Species richness.

Simpson's index

47
Table 10. Sample tabulated output of a seagrass assessment activity.

SITE CHARACTERISTICS AGUTAYAN RABOR MELVILLE

Sitio Totowaan Burisanga Pinaatan
Longitude 7°51’53.9”N 7°53’3.2”N 7°48’53.6”N
Latitude 116°58'36.3"E 116°57'27.3"E 117°1'34.5"E
Number of quadrats 8 8 11
Sediment type Sandy Sandy-muddy Sandy-silty
Water condition Turbid Low tide A bit turbid
Strong water Nearly or exposed Near the bay’s
Other observations/remarks
movement directly to air mouth
Estimated seagrass (ha) 977.0 907.5 208.2
Diversity Indices
Shannon-Weiner diversity index (H’) 0.36 1.38 1.35
Simpson’s diversity index (D) 0.20 0.68 0.67
Margalef’s index (DMg) 0.17 0.93 0.86
Evenness of species (E) 0.52 0.71 0.69
Number of seagrass species
2 7 7
(in quadrats)

BOX 2. ANALYSIS QUESTIONS

FOR LOCAL APPLICATION

To integrate and summarize the previous sections (from Introduction to Assessing

and Monitoring of Seagrass Ecosystems), the users of this module are asked to
answer the following key questions. This is to apply the seagrass module in local
setting.
1. Have you identified potential seagrass sampling site/s in your area?
2. What are the seagrass species present in the area? Any dominant or widely seen
species?
3. Can you identify possible threats to the seagrass ecosystem in your locality?
4. Do you have any plan to do seagrass assessment and possibly monitoring within
your jurisdiction? If so, what is/are the objective/s?
5. Can you describe the sampling design in mind? Who will be the people involved
in the assessment?
6. How do you intend to sustain the efforts and enthusiasm at the community
level?

48
 5. APPLICATIONS TO ECOSYSTEM MANAGEMENT
AND CONSERVATION

DRIVERS-PRESSURES-STATE-IMPACT-RESPONSE: A CONCEPTUAL
FRAMEWORK FOR ADAPTIVE MANAGEMENT

49
Table 11. Pressure-state-response model for managing seagrass ecosystems.

PERFORMANCE
SEAGRASS STATE THREAT/ PRESSURE RESPONSE
INDICATORS
Seasonal fluctuations Seagrass abundance Seasonal cycles in Natural phenomenon
in seagrass temperature, light, Continue water quality
density/cover salinity, and nutrients management programs
and distribution
Sudden phytoplankton, Seagrass abundance Exotic (introduced) Check for introduced
macroalgal, or Epiphyte and epifauna phytoplankton, species
epiphyte blooms cover macroalgal, or epiphyte Implement port and shipping
Health of associated species controls to avoid
fisheries stocks introducing “alien” species
Smothering and death Seagrass abundance Pollution and Improve water quality and
of seagrass due to Epiphyte cover eutrophication land practices,
excessive and Health of associated (high nutrient loads) e.g., revegetation
persistent epiphyte fish stocks from sewage and Enforce urban, industrial, and
cover and agricultural, industrial, agriculture pollution
phytoplankton and urban run-off controls
densities Strictly implement
Republic Act No. 9003
(Solid Waste Management
Act) and other
environmental laws
Widespread die-off Seagrass abundance Proliferation of disease Improve water quality,
of meadows Health of associated (e.g., fungal pathogens, reduce local stresses,
following chronic fisheries stocks viruses, bacteria), likely and enforce pollution
senescence following stress controls
Sudden loss and/or Seagrass abundance Floods (nutrient load, Implement preventive
burial of seagrasses, Substrate and sediment low salinity, sediment measures (e.g., improved
outside the scale of characteristics redistribution leading dredging methods)
seasonal changes to burial) Reduce local stresses
Dredging programs (burial and allow natural recovery
from dredge-related
sediment plumes)
Overgrazing Seagrass abundance Herbivores (e.g., dugong, No tested treatment
on seagrass Herbivore population sea turtles, sea urchin)
meadows size in the absence of natural
competitors or
predators due to
overfishing
Source: Long and Thom (2001)

50
51
REFERENCES

52
53
IUCN (2021) Reference List

54
55
 APPENDIX

VISUAL GUIDE FOR ESTIMATING SEAGRASS PERCENT COVER

Seagrass Percent Cover Visual Guide

Seagrass-Watch - Philippines

At Reef top; Cymodocea and Halodule

56
Seagrass Percent Cover Visual Guide
Seagrass-Watch - Philippines

At Reeftop: Thalassia, Cymodocea, and Enhalus

57
Seagrass Percent Cover Visual Guide
Seagrass-Watch - Philippines

Coastal area at low tide

58
Seagrass Percent Cover Visual Guide
Seagrass-Watch - Philippines

Coastal area at low tide

59
Seagrass Percent Cover Visual Guide
Seagrass-Watch - Philippines

Coastal area at high tide

60
 Seagrass Percent Cover Visual Guide
Seagrass-Watch – Philippines

2% 5%

7% 17%

25% 38%

60% 70%
Coastal area: H. ovalis

61
Seagrass Percent Cover Visual Guide
Seagrass-Watch - Philippines

At reeftop; Enhalus

62
Seagrass Percent Cover Visual Guide
Seagrass-Watch - Philippines

Subtidal area

63