Assessment Proposed Location Sewage Plant

NATURE FOUNDATION
Assessment Proposed Location
Sewage Plant
Mailing address
P. O. Box 863
Philipsburg
St. Maarten
Netherlands Antilles
Physical address
Wellsberg Street 1 A
Unit 25—26
Cole Bay
St. Maarten
Netherlands Antilles
Phone: 599-544-4267
Fax: 599-544-4268
E-mail
[email protected]
www.naturefoundationsxm.org
Nature Foundation St. Maarten
An Affiliate of
1. Introduction
This document acts as a brief summary of assessment dives and ecological
monitoring which was carried out at the location for the proposed Sewage Treatment
Plant in the Simpson Bay Lagoon. This document lays forth the Information and
Methods for the Biological research project to determine the ecological composition of
the proposed area. Methods have been: The Seagrass Net Monitoring Protocol
(http://www.seagrassnet.org/global-monitoring) and Point Intercept Counts Developed
to measure Fish and Invertebrates Abundance. Monitoring through the use of Transact
Lines and through the deployment of Quadrates and Point Intercept Counts.
1.2 Sea Grasses
Seagrasses are flowering plants that live underwater. Like land plants, seagrasses
produce oxygen. The depth at which seagrasses are found is limited by water clarity
which determines the amount of light reaching the plant. Seagrass beds form in
shallow coastal lagoon areas. The main species of seagrass found around St Maarten
are Turtle grass (Thalassia testudinum) and Manatee grass (Syringodium filiforme).
Seagrass ecosystems are considered to be amongst the most productive in the world;
an average growth rate of seagrass leaves is about 5mm per day, with entire stands of
seagrass being turned over every 16 weeks with 3-4 crops annually (Edwards, 2000).
In addition to this, the blades of seagrasses provide a huge surface area for settlement
of epiphytes (plants that live on the surface of another organism such as calcareous
green algae, crustose coralline red algae, cyanobacteria, diatoms and epifauna
(animals that live on the surface of another organism such as sponges, hydroids,
bryozoans, foraminiferans). For a square metre of seabed, a dense seagrass stand
may have 20m2 of leaf area for other organisms to settle on. The productivity of the
epiphytes can be twice that of the seagrasses themselves,
The seagrass stands in around St Maarten are dominated by Turtle grass (Thalassia
testudinum) together with Manatee grass (Syringodium filiforme) and banks of
calcareous alga (Halimeda sp). Through a succession of growth (see Figure 14),
seagrasses can turn vast areas of unconsolidated sediments into highly productive
plant dominated, structured habitat with a diversity of microhabitats.
2
Solid substrate
Epilithic
algae
Coralline algae
Halimeda
THALASSIA
Sandy
substrate
Syringodium
Rhizophytic
algae
Halodule
Muddy
substrate
Ecosystem Development
Stable environmental conditions
Bare substrate
Low productivity
Little shelter, habitat, food
Unstable substrate
Few human uses
Disturbance
Thalassia climax
High productivity
Shelter, Habitat, Food
Stable substrate
Many human uses
Figure: Seagrass succession diagram (Edwards, 2000)
Significant invertebrates in the seagrasses of St Maarten include a much reduced
population of Queen Conch (Strombus gigas), Cushion Stars (Oreaster reticulata),
Sea Cucumber (Holothuria mexicana), Sea Urchins (Tripneustes venricosus,
Lytechinus variegates, Meoma ventricosa) and the Upside Down Jellyfish (Cassiopeia
frondosa).
Image: A mixture of Turtle Grass (Thalassia testudinum) and Manatee Grass
(Syringodium filiforme) at Oyster Pond (source: NAFSXM).
3
1.3 Condition
The seagrasses in Simpson Bay Lagoon have all but disappeared as a result of
pollution, anchoring and eutrophication caused by excessive nutrients entering coastal
waters. The overfishing of Queen Conch (Strombus gigas) has also disrupted the
dense root networks of the seagrasses removing their sediment binding and trapping
function which results in murkier waters and mobile sediments.
Dredging of vast areas of seagrass in the lagoons and bays for land reclamation has
lead to the destruction of much of the seagrass habitat of St. Maarten. Dredging and
landfill continue to threaten the remaining areas of seagrass around the island.
An additional threat to native seagrass population is the invasive Halimaeda
stipulacea, which was probably introduced via boating traffic. The Nature Foundation
is currently investigating the range and extent of this species.
Seagrasses can be transplanted easily and projects can be initiated whereby Nature
Foundation staff replants areas of seagrass beds into areas where the seagrass has
been reduced.
In order to investigate seagrass population the Nature Foundation uses SeagrassNet
Scientific Seagrass monitoring protocol (http://www.seagrassnet.org/)
1.4 Value
The seagrass beds of St Maarten provide a biological filter system for the waters
within the bays and lagoons. This should give the water its striking azure blue colour
which is an essential feature to attract Tourists to the area, which in turn supports local
businesses. The seagrasses also prevent terrestrial sediments from reaching the reef
where they would smother and kill coral reef organisms.
The seagrass beds also provide a nursery and habitat for numerous commercially and
recreationally valued marine animals such as Conch and juvenile fish. Internationally
endangered species such as turtles also depend on the well being of the seagrass for
their survival.
Monitoring will involve the deployment of 50 meter transact lines and the counting of
species along those lines using quadrates. All species within the quadrates, including
a point intercept segment for mobile and sessile organisms, will be included. Data will
be recorded on underwater data sheets.
1.5 Mangroves
Mangrove forests world-wide are under severe pressure and disappearing in an
alarming rate. It is estimated that about 60% of the total mangrove areas in the world
have disappeared. This is mainly contributed to large scale land clearance for coastal
development. Mangroves are trees growing in inter tidal areas. Around St Maarten,
four species of mangroves can be found; Rhizophora mangle (Red mangrove),
Avicennia germinans (Black mangrove), Laguncularia racemosa (White Mangrove)
and Conocarpus erectus (Buttonwood). Simpson Bay had the most significant stand of
mangroves on St Maarten, although coastal developments in the past have removed
much of the forest.
4
Mangrove forests grow in a pattern from the native terrestrial plants through to the
highly adapted Red Mangroves with their specialised prop roots. Table 2 summarises
the characteristics of the different vegetation zones.
Vegetation that grows on land and is intolerant of salty soil or
Terrestrial water, such as Pepper Cinnamon (Canella alba), Black
vegetation Loblolly (Pisonia subcordata), Choaky Berry (Eugenia
axillaris), and ferns.
The white mangrove, Laguncularia racemosa, usually
occupies the highest elevations farther upland than either the
red or black mangroves. Unlike its red or black counterparts,
White
the white mangrove has no visible aerial root systems. The
mangrove
easiest way to identify the white mangrove is by the leaves.
zone
They are elliptical, light yellow green and have two
distinguishing glands at the base of the leaf blade where the
stem starts (See Appendix 3).
The black mangrove, Avicennia germinans, usually occupies
Black
slightly higher elevations upland from the red mangrove. The
mangrove black mangrove can be identified by numerous finger-like
zone
projections, called pneumatophores, which protrude from the
soil around the tree's trunk.
The red mangrove, Rhizophora mangle, is probably the most
Red
well-known. It typically grows along the water's edge,
mangrove especially around Simpson Bay. The red mangrove is easily
zone
identified by its tangled, reddish roots called ‘prop roots’. The
roots are usually exposed at low tide but covered at high tide.
Table 1: Typical Mangrove zonation in St Maarten
The mangrove forests on St Maarten provide a habitat for a number of different plants
and animals dispersed from the muddy sediments through the trees into the canopy
(see Figure 15). These include many invertebrates, reptiles, fish and birds.
Arboreal (tree) fauna
e.g. birds, reptiles,
insects
Marine hard bottom flora
and fauna e.g. hydroids
and bivalves.
Marine soft-bottom fauna
e.g. Polychaete worms,
mollusks, crustaceans
High tide
Marine fauna visitors at
high tide e.g. fish, crabs
and prawns
Low tide
Figure: The vertical distribution of large animals in mangrove forests
Significant invertebrates in the mangroves of St Maarten are similar to those found in
seagrasses e.g. Queen Conch (Strombus gigas), Milk Conch (Strombus costatus),
Cushion Stars (Oreaster reticulata), Sea Cucumber (Holothuria mexicana), Sea
5
Urchins (Tripneustes venricosus, Lytechinus variegates, Meoma ventricosa) and the
Upside Down Jellyfish (Cassiopeia frondosa). The Atlantic Triton (Charonia variegate).
Many different fish species use the mangroves of St Maarten as a habitat. The species
most likely to be seen include; Striped Parrotfish (Scarus croicensis), Bluehead
(Thalassoma bifasciatum), Silversides, Herrings and Anchovies (families Atherinidae,
Clupeidae, Engraulidae). Other interesting species that use the mangroves include
Spotted Eagle Rays (Aetobatus narinari), various species of Moray Eels and young
sharks.
Image: A Red Mangrove (Rhizophora mangle) at Oyster Pond with its characteristic
stilt roots. (Source: NAFSXM)
Several species of birds breed in the on and around the mangroves of St Maarten,
these species include: American Coot (Felucia Americana), Moorhen (Gallinula
chloropus), Yellow-crowned Night Heron (Nyctanassa violacea), Green Heron
(Butorides striatus), Black-winged Stilt (Himantopus himantopus) and several plovers.
Simpson Bay Lagoon is an important nesting ground for many more species and a
roosting ground for migratory species on their route south (Brown & Collier, 2005).
1.6 Location
All four mangrove species are found along the south side of Simpson Bay. Red
Mangrove dominates near the airport and followed by a strip of Black and White
Mangroves, while Button Wood grows further inland. This Mangrove stand becomes
denser near Mullet Bay, where White Mangrove dominates. The cove at Cupecoy and
Little Bay Pond also has stands of mangrove woodland.
1.7Condition
All of the mangroves on St Maarten are currently threatened by pollution and
development (Image Group 14), even though they only cover a very small area of the
coastline. Around Little Bay Pond, Red Pond and Fresh Pond small Mangrove stands
remain, but without any significant Red Mangrove growth. Hurricane Luis in
September 1995 caused severe damage to the mangrove forests, especially to the
6
Red Mangroves. This highlighted the importance of mangroves in their coastal
protection role. Some seedlings did survive the hurricane which alongside a NFSXM
initiated planting programme in 2004/2005 should help to re-establish mangroves in
critical areas.
Image Group: Dead and disturbed mangroves at Mullet Bay (Source: NAFSXM).
1.8Value
The mangroves that still exist on St Maarten are an important sanctuary, breeding and
foraging ground for many wetland birds, marine invertebrates and fish. In the past, the
bays have also been home for two globally endangered species: Green Turtles
(Chelonia mydas) and Queen Conch (Strombus gigas).
Mangroves act as a filter for water being washed off the land by preventing harmful
sediments from smothering the coral reef. By establishing themselves successfully,
the mangrove trees become a thriving habitat for many other plants and animals as
well as an important nursery for many species of fish. Fish using the mangroves as a
nursery include Schoolmasters (Lutjanus apodus), Gray Snapper (Lutjanus griseus),
Great Barracuda (Sphyraena barracuda) and the Foureye butterfly (Chaetodon
capistratus).
A baseline survey of healthy marine ecosystem
been developed by the Nature Foundation in
their density and distribution are determined
specimens as well as sub aqua monitoring
individual counts of flora and fauna.
needs to be made. A set program has
which mangroves are monitored and
based on point counts of individual
using point intercepts and speciatic
7
1.9 Water quality, sediment and biological monitoring
Continuous Water Quality monitoring has to be conducted in order to determine:
1) If positive effects occur with the implemented recommended proposals stated in this
assessment, especially regarding the wastewater disposal into the Lagoon;
2) Or to alert in case the water quality in certain areas is declining.







There are various parameters necessary for the monitoring of water quality:
Temperature, pH, salinity, dissolved oxygen, turbidity, suspended particles, particle
organic carbon and NTK;
Nutrients (Nitrates, phosphates, ammonia);
Micro-contaminants: heavy minerals, detergents, total hydrocarbons;
Bacteria and viruses: total coliforms, fecal coliforms and streptatoccifecal;
Sediment:
Nutrients (Nitrates, phosphates, ammonia);
Hydrocarbons and heavy metals;
Granulometry and particles percentage < 63 m;
Biological and ecological:

Chlorophyll-a;

Seagrass and seaweed beds;

Benthos surveys.
Species Composition:
The below Species Composition table will be used to record all species within the one
meter quadrates. These species have been previously determined as being present
within the Simpson Bay Lagoon. Point Counts during the Transects will be carried out
and recorded on Data Forms and subsequently analyzed. See later sections for the
use of indicator species.
Species List Simpson Bay Lagoon
Molluscs:
Bulla striata
Chione paphia
Cerithium eburneum
Spondylus spp.
Echinodermata:
Holothuria mexicana
Coelenterates:
Cassiopea andromeda
Benthic Foraminifera continued
Rosalina sp.
Articulina tubulosa
Bulimina costata
Textularia sp.
Nonionella sp.
Planispirinoides bucculentus
Dentostomina sp.
Pyrgo sp.
Quinqueloculina granulocostada
Echinodermes
8
Porites porites
Macro-Algae:
Thalassia testillinum
Wrangelia penicillata
Acetabularia calculus
Penicillus pyriformis
Seagrasses:
Syringodium filiforme
Halophila decipiens
Thalassia testudinum
Worms:
Eupolymnia crassicornis
Ostracodes:
Loxochonca elliptica
Cypredeis torosa
Pontocypris littoralis
Benthic Foraminifera
Quinqueloculina pseudoreticulata
Quinqueloculina sp.
Spirolina arietina
Spiroloculina angulata
Triloculina rupertiana
Phanerogames marines
Halimeda incrassata
Caulerpa sertularinoides
Caulerpa prolifera
Caulerpa languginosa
Avrainnvillea lonficaulis or decipiens
Chondria spp.
Cladophores spp.
Halimeda monile
Hypnea spp.
Archais angulatus
Miliolinella sp.
Peneroplis planatus
Elphidium crispum
Planispiriniella exigua
Quinqueloculina intricata
Sorites marginalis
Ammonia beccarii
Articulina tubulosa
Cornuspira involutens
Planorbulina acervalis
Hauerina involuta
Kerreriella sp.
2. Site Selection
Sites were selected based on the proposed location of the to be built sewage
treatment plant for the Simpson Bay Lagoon Area.
Note on GPS Coordinates
The contracting party submitted coordinates in the Universal Transverse Mercator
System (UTM) which is not supported by on-board GPS systems. Therefore for the
purpose of this report the coordinates had to be changed from the UTS system to
Geodetic using the following parameters: The longitudes of the central meridians are 3
+ 6 * (N - 1), where N represents a zone number in the range from 1 to 60. There are
seven non-standard zones, the scale factor along the central meridian is 0.9996., the
Y value has an origin of 0 meters at the equator, the X value, has an origin of 500,000
9
meters at the central meridian. Based on these calculations the respective Geodetic
coordinates were arrived at.
Figure showing both monitoring locations
3. Biota and Substrate Surveying
Biota was surveyed using a modified version of the Reef Check Monitoring Method.
The methodology was adapted in order to reflect the ecosystems found within the
Simpson bay lagoon, particularly with regards to Seagrassess, invertebrates and fish
species.
A modified Reef Check method was used to determine the state of the living biota
within the lagoon and is a method used all over the world to gauge the health of living
organisms. Fish, invertebrate and substrate data are collected to get an overall view
on the health of the reef ecosystem using indicator species.
Reef Check surveys are conducted using a 100 meter transect line. Data is collected
from 0 meter to 20 meter, from 25 meter to 45 meter, from 50 meter to 70 meter and
from 75 meter to 95 meter away from the start of the line (Figure 2). There are three
different protocols which are filled out during this survey, namely fish, invertebrates
and substrate. The fish and invertebrate data is collected using indicator species. For
the fish survey a five by five meter square with the transect line in the middle of the
bottom of the square is used. All species within this area are counted (Figure 3). All
invertebrates which are within 2.5 meters of each side of the line are recorded in the
protocol (picture 4). To assess the substrate a one metre squared quadrat (square
metal ring) is put down on every 0.5 meters of the transect line and all the substrate
which it touches is recorded.
Distance in m:
0
20
25
45
50
70
Figure 2 Reef Check Transect line. This figure shows a transect line used for Reef Check. Data is collected
only on the orange part of the line.
10
a
b
5m
5m
5m
Figure 3 Method to collect fish and invertebrate data. This figure shows how the data for the fish and
invertebrates is collected on the transect line. The transect line is shown in orange. a Method to collect fish
data. All indicator fish species in a square of five by five meter around the transect line are accounted for. b
Method to collect invertebrate data. All indicator invertebrate species within 2.5 meter of either side of the
transect line are recorded.
Picture Researcher conducting surveys using quadrats.
For the graphs used in this study, the total amount of fish data and invertebrate data
per transect line were used.
From the substrate data the percentage of ground covered by substrate type were
utilized. Since the transect line is split into segments, the standard error plotted in the
graphs is the standard error of the mean of the data sets.
In order to get an idea of the substrate type and cover and fish and invertebrate
abundance indicator species were used. Rather than record all species present during
the transact lines a subset of species were chosen based on their importance to the
ecosystem and their presence or absence being an indicator of overall health and
biodiversity.
11
3.1 Seagrasses and Algae
Seagrasses are flowering plants that live underwater. Like land plants, seagrasses
produce oxygen. The depth at which seagrasses are found is limited by water clarity
which determines the amount of light reaching the plant. Seagrass beds form in
shallow coastal lagoon areas. The main species of seagrass found around St Maarten
are Turtle grass (Thalassia testudinum).
Seagrass ecosystems are considered to be amongst the most productive in the world;
an average growth rate of seagrass leaves is about 5mm per day, with entire stands of
seagrass being turned over every 16 weeks with 3-4 crops annually. In addition to this,
the blades of seagrasses provide a huge surface area for settlement of epiphytes
(plants that live on the surface of another organism such as calcareous green algae,
crustose coralline red algae, cyanobacteria, diatoms and epifauna (animals that live on
the surface of another organism such as sponges, hydroids, bryozoans,
foraminiferans). For a square metre of seabed, a dense seagrass stand may have
20m2 of leaf area for other organisms to settle on. The productivity of the epiphytes
can be twice that of the seagrasses themselves,
The seagrass stands in around St Maarten are dominated by Turtle grass (Thalassia
testudinum) calcareous alga (Halimeda sp). Through a succession of growth (see
Figure 14), seagrasses can turn vast areas of unconsolidated sediments into highly
productive plant dominated, structured habitat with a diversity of microhabitats.
Solid substrate
Epilithic
algae
Coralline algae
Halimeda
THALASSIA
Sandy
substrate
Syringodium
Rhizophytic
algae
Halodule
Muddy
substrate
Ecosystem Development
Stable environmental conditions
Bare substrate
Low productivity
Little shelter, habitat, food
Unstable substrate
Few human uses
Disturbance
Thalassia climax
High productivity
Shelter, Habitat, Food
Stable substrate
Many human uses
Figure: Seagrass succession diagram (Edwards, 2000)
Significant invertebrates in the seagrasses of St Maarten include a much reduced
population of Queen Conch (Strombus gigas), Sea Cucumber (Holothuria mexicana),
Sea Urchins (Diadema spp.) and the Upside Down Jellyfish (Cassiopeia andromeda).
12
Image: Turtle Grass (Thalassia testudinum)
Condition
The seagrasses in Simpson Bay Lagoon have all but disappeared as a result of
pollution, anchoring and eutrophication caused by excessive nutrients entering coastal
waters. Overfishing within the lagoon has also disrupted the dense root networks of
the seagrasses removing sediment binding and trapping function which results in
murkier waters and mobile sediments.
Dredging of vast areas of seagrass in the lagoons and bays for land reclamation has
lead to the destruction of much of the seagrass habitat of St. Maarten. Dredging and
landfill continue to threaten the remaining areas of seagrass around the island.
Research was also conducted on the presence of Nutrient Indicator Algae which
shows heavy nutrient loading in areas where this alga was recorded.
An additional threat to native seagrass population is the invasive Halimaeda stipulacea
(Appendix), which was probably introduced via boating traffic. This species was
included in the research in order to gauge the extent of this invasive species.
Value
The seagrass beds of St Maarten provide a biological filter system for the waters
within the bays and lagoons. This should give the water its striking azure blue colour
which is an essential feature to attract Tourists to the area, which in turn supports local
businesses. The seagrasses also prevent terrestrial sediments from reaching the reef
where they would smother and kill coral reef organisms.
The seagrass beds also provide a nursery and habitat for numerous commercially and
recreationally valued marine animals such as lobster and juvenile fish. Internationally
endangered species such as turtles also depend on the well being of the seagrass for
their survival.
Chosen indicator species for the results of this study are Thalassia testudinum (TT),
nutrient indicator algae (NIA), Halophilia decepidens (HD), Halophilia stipulacea (HS),
13
and Acetabularia calyculus (AC). Sponges (SP) were also recorded in the substrate
section which shows the presence of suitable water quality and which also provides a
filtering mechanism to the ecosystem. Sand (SD), rock (RC), and silt/clay (SI) were
also recorded to show substrate damage and sedimentation respectively.
The value Damage (DM) was also included to show damage caused to the substrate.
Due to the diverse nature of impacts within the Simpson Bay Lagoon it was chosen to
include a general value to reflect damage as is opposed to listing every incidents of
damage recorder. Damage includes but is not limited to anchor halos, anchor scarring
from dragging, ship groundings, damping of material and any other value which can
show damage to substrate.
3.2 Fish
The Simpson Bay Lagoon is an important nursery area for the sea surrounding it. The
mangroves and seagrass beds provide important habitat for juvenile fish species and
also provide habitat for specific fish in general. Five species of indicator species were
chosen for the purposes of this study: Butterflyfish, Haemulidae, Snapper, Parrotfish,
and Moray eel. These represent each segment of niche species represented within the
lagoon namely algal grazers (butterflyfish), bottom grazers (Haemulidae), predator
mobile (snapper), predator sessile (moray eel) and grazers hard substrate (parrotfish).
3.3 Invertebrates
Invertebrates can be commercially valuable and can also have an important
ecosystem function, grazing on poorly settled substrate and ensuring proper root
placement. Eight invertebrates were chosen to act as indicators for the overall health
of the lagoon. They have been divided in molluscs which provide stability (Bulla
Striata, Spondylus spp), grazers (Diadema spp., Holothuria mexicana, Echinodermes),
and commercially important species which can show if there is any fishing pressure
(Panulirus argus). Echinodermes were especially included to reflect the natural
degradation of the ecosystem. This phylum is especially sensitive to changes in
environmental quality and their presence or absence can indicate stressors to the
environment.
14
4. Biota and Substrate Survey Results
Site MonLoc1 N. 6347/171 E. 4265.890
Number of Specimen
Recorded Fish Species
3.5
3
2.5
2
1.5
1
0.5
0
Butterflyfish
Haemulidae
Snapper
0-20m 25-45m 50-70m 75-95m Total
Mean
TYB
SD
Parrotfish
Moray eel
Quadrat Distance
Number of Specimens
Invertebrates
3.5
3
2.5
2
1.5
1
0.5
0
Bulla Striata
Spondylus spp.
Diadema spp.
Holothuria mexicana
Echinodermes
Cassiopea andromeda
Panulirus argus
Quadrat Distance
Benthos Composition
TT
NIA
HD
DM
HS
SP
SD
AC
RC
SI
15
Site MonLoc2 N. 5892.537 537 E. 4602.503
Number of Specimen
Recorded Fish Species
3.5
3
2.5
2
1.5
1
0.5
0
Butterflyfish
Haemulidae
Snapper
0-20m
2545m
5070m
7595m
Total Mean
SD
Parrotfish
Moray eel
TYB
Quadrat Distance
Number of Specimens
Invertebrates Site
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Bulla Striata
Spondylus spp.
Diadema spp.
Holothuria mexicana
Echinodermes
025- 50- 75- Total Mean SD
20m 45m 70m 95m
Cassiopea andromeda
Panulirus argus
Quadrat Distance
Benthos Composition Site
TT
NIA
HD
DM
HS
SP
SD
AC
RC
SI
16
Conclusion on Biota Results:
Results show that for the Simpson Bay Lagoon the biodiversity, both for vertebrate fish
species, invertebrates, molluscs and crustacea and seagrass cover the biodiversity in
both areas is quite high. This will be severely impacted if additional fill occurs.
Comparison with other areas: Cole Bay Corner
In order to illustrate the level of biodiversity of the monitored area a comparison was
made with a section of the Simpson Bay Lagoon with eroded biodiversity: the Cole
Bay Corner section illustrated in the satellite imagery below:
Site COMP N. 4906.251 E. 6031.158
Number of Specimen
Recorded Fish Species
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Butterflyfish
Haemulidae
Snapper
0-20m
2545m
5070m
7595m
Total Mean
SD
Parrotfish
Moray eel
TYB
Quadrat Distance
17
Number of Specimens
Invertebrates Site
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Bulla Striata
Spondylus spp.
Diadema spp.
Holothuria mexicana
Echinodermes
Cassiopea andromeda
Panulirus argus
Quadrat Distance
Benthos Composition
TT
NIA
HD
DM
HS
SP
SD
AC
RC
SI
The results clearly indicated that the section shows a marked erosion of biota and
substrate cover as is compared to the sites monitored at the proposed location of the
sewage treatment plant.
18
5. Introduction water quality testing
The St. Maarten Nature Foundation tested water quality at the two monitored locations
as well as at the control site for comparative purposes.
A water quality study was also undertaken to determine if the water of Simpson Bay
Lagoon is polluted and to see if any changes occurred with previous water quality
studies carried out in 1997 by French Saint Martin and again by a group or
researchers in 2002.
Tests were carried out in order to determine Nitrate, Phosphate, Nitrogen, Dissolved
Oxygen, pH levels and Temperature levels, Salinity, Turbidity, and the Presence or
Absence of Coliforms Bacteria.
5.1 Methods
Samples were collected using standard sampling vials. Once collected the samples
were tested for the various levels within 24 hours using the Lamotte Water Pollution
testing kit (figure 2). Once levels were measured the data was recorded and stored.
pH levels and water temperature were tested in situ using the Oakton Acorn Series
pre-calibrated pH meter. Similarly the Salinity was measured using an Oakton Salinity
Meter. Turbidity was determined using a Turbidity Tube (see Appendix X)
Figure 2: Lamotte Water quality testing kit
Sampling
Sampling water was done with great care in order to avoid cross contamination and a
skewing of results. Sampling vials were rinsed with the to be sampled water at least
five times to remove any previous contaminants. Water samples were taken right
below the surface through submersion of the sampling vial. Dissolved oxygen, Salinity,
pH and temperature were tested in situ while the other parameters were tested in the
Nature Foundation Offices.
19
Dissolved oxygen
Direct reading titration procedure, uses a modified Winkler method. Range 0.2 to 1.0
ppm (0.2 ppm interval), five reagents.
Nitrates
Quartet comparator method, uses the modified A.P.H.A. reagent system. Range 0.2
ppm to 1.0 ppm (0.2 ppm, 0.4 ppm, 0.6 ppm, 1.0 ppm), four reagents.
Phosphate
Quartet comparator method, uses the absorbic acid method to produce a series of
blue colours. Range 0.2 ppm to 1.0 ppm (values 0.2, 0.4, 0.6, 0.8, 1.0 ppm), four
reagents.
PH and Temperature
Using Pre-calibrated Meter
Salinity
Using Pre-calibrated Meter
Picture <> recording salinity , pH and Temperature using a pre-calibrated meter.
Total Coliform
A five-tube method to detect the presence or absence of Total Coliform Bacteria.
Results compare favourably to five-tube MPN method. Incubation time in 44-48 hours,
no incubation labware required.
20
Turbidity
Secchi Disc method. A bi-colour Secchi disk with a weight attached is lowered over
board to a depth where the Secchi disk cannot be seen by the sampler and an extra
observer. The disk is attached to a line which is marked in fifty centimetre increments.
The length of line is noted and then converted into NTU’s using the conversion table.
Appearance of a Secchi Disc.
Depth and location coordinates: These measurements were carried out with a GPS
(Global Positioning System).
Picture: Lowering of Secchi disk overboard to check for turbidity
Picturex: Secchi disk is lowered until disk is no longer visible
5.2 Results
Follows are the results gathered from the water quality tests:
Nitrates (No)
Sewage is the main source of nitrates added by humans to marine and wetland areas.
Sewage enters waterways in inadequately treated wastewater from sewage treatment
plants, in the effluent (outflow) from illegal sanitary sewer connections, and from poorly
functioning septic systems. Water containing high nitrate levels can cause, amongst
others, a serious condition called methemoglobinemia, if it is consumed. This condition
prevents an infant’s blood from carrying oxygen; hence the nickname "blue baby"
syndrome.
Site #
No
Site #
No
MonLoc1
.5 ppm
Control
.6 ppm
MonLoc2
.3 ppm
21
Phosphates (Po)
Phosphorus is usually present in natural water as phosphates (orthophosphates,
polyphosphates, and organically bound phosphates). Phosphorus is a plant nutrient
needed for growth and a fundamental element in the metabolic reactions of plants and
animals (hence its use in fertilizers). Sources of phosphorus include human and
animal wastes (i.e., sewage), industrial wastes, soil erosion, and fertilizers. Excess
phosphorus causes extensive algal growth called "blooms," which are a classic
symptom of cultural eutrophication and lead to decreased oxygen levels in wetlands
and enclosed marine environments.
Site #
Po
Site #
Po
MonLoc1
.4 ppm
Control
.5 ppm
MonLoc2
.3 ppm
3.3 Nitrogen (Nh3)
Ammonia, a by-product of nitrogen, is toxic to fish and aquatic organisms, even in very
low concentrations. When levels reach 4 ppm fish can suffer gill damage. When levels
reach 5 ppm, sensitive fish can begin to die. As levels near 7 ppm, even ammoniatolerant fish can begin to die. Ammonia levels greater than approximately 2 ppm
usually indicates polluted waters.
The danger ammonia poses for fish depends on the water’s temperature and pH,
along with the dissolved oxygen and carbon dioxide levels; the higher the pH and the
warmer the temperature, the more toxic the ammonia. Also, ammonia is much more
toxic to fish and aquatic life when water contains very little dissolved oxygen and
carbon dioxide.
Site #
NH3
Site #
NH3
MonLoc1
.3 ppm
Control
.4 ppm
MonLoc2
.3 ppm
3.4 Dissolved Oxygen (O)
Dissolved oxygen analysis measures the amount of gaseous oxygen (O2) dissolved in
an aqueous solution. Oxygen gets into water by diffusion from the surrounding air, by
aeration (rapid movement), and as a waste product of photosynthesis.
Total dissolved gas concentrations in water should not exceed 15 ppm.
Concentrations above this level can be harmful to aquatic life. Fish in waters
containing excessive dissolved gases may suffer from "gas bubble disease"; however,
this is a very rare occurrence. The bubbles or emboli block the flow of blood through
blood vessels causing death. External bubbles (emphysema) can also occur and be
seen on fins, on skin and on other tissue. Aquatic invertebrates are also affected by
gas bubble disease but at levels higher than those lethal to fish. Inversely gas levels
should not go below 5 ppm, which can show a lack of oxygen and can cause fish dieoffs and algal blooms.
22
Site #
O
Site #
O
MonLoc1
5.5 ppm
Control
7.5 ppm
MonLoc2
5.5 ppm
Alkalinity (pH) and Temperature
A range of pH 6.5 to pH 8.2 is optimal for most organisms. Most organisms have
adapted to life in water of a specific pH and may die if it changes even slightly. The
toxicity level of ammonia to fish, for example, varies tremendously within a small range
of pH values. Acidic water can cause heavy metals such as copper and aluminium to
be released into the water. Copper from worn automobile brake pads is often present
in runoff. Rapids growing algae remove carbon dioxide from the water during
photosynthesis, which can result in a significant increase in pH levels.
Temperature is a basic parameter and is measured on a regular basis with water
quality testing. Changes in temperature can affect certain biological processes, for
example organic matter consumes oxygen less rapidly in colder water than in warmer
water, so that warm waters contain less oxygen. Although not a crucial indicator within
the Simpson Bay Lagoon, an above normal temperature can result in increased algae
blooms and bleaching of certain aquatic organisms.
Site #
pH
Temp
Site #
pH
Temp
MonLoc1
8.0
26 C
Control
8.2
26 C
MonLoc2
8.0
26 C
23
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term
used to describe the levels of different salts such as sodium chloride, magnesium and
calcium sulphates, and bicarbonates. It is important to understand the level in salinity
in the various areas of the Lagoon in order to determine mixing, fresh water
introduction and hyper or hypo-saline environments within the Simpson Bay Lagoon.
The values for salinity are expressed in parts per thousand (ppt)
Site #
ppt
Site #
ppt
MonLoc1
34.7
Control
34.7
MonLoc2
34.7
Turbidity
Turbidity is the cloudiness or haziness of a fluid caused by individual particles
(suspended solids) that are generally invisible to the naked eye and is a key test of
water quality. Poor turbidity can be caused by growth of phytoplankton or algae related
to human activities. Some human activities and impacts conducted around the
Simpson Bay Lagoon such as construction and dredging, can lead to high sediment
levels causing high turbidity. Runoff from the surrounding hills and from the Cole Bay
valley from a rain event can also cause higher turbidity levels. Areas prone to high
bank erosion rates as well as urbanized areas around Cole Bay/ Simpson Bay may
also contribute large amounts of turbidity. It is important to note that for many
mangrove areas, high turbidity is needed to support certain species, such as to protect
juvenile fish from predators. For most mangroves species still found within the
Simpson Bay Lagoon, turbidity levels as high as 1.7 Attenuation Coefficient Units (AC)
are needed for proper ecosystem functioning.
A Secchi disk measurement should always be taken off the shady side of a boat or
dock between 9 a.m. and 3 p.m.[2] The period for best results is between 10 am and 2
pm. The same observer should take Secchi depth measurements in the same manner
every time. One can approach the measurement by lowering the disk beyond a point
of disappearance, then raising it and lowering it slightly to set the Secchi depth.
Another method is to record the depth at which the disk disappears, lower another few
feet, then record the depth at which the disk reappears as it is slowly brought up. The
Secchi depth is taken as the average of the two values.
The Secchi depth is reached when the reflectance equals the intensity of light
backscattered from the water. This depth in metres divided into 1.7 yields an
attenuation coefficient.
24
Picture: Secchi disk is lowered until disk is no longer visible
Site #
AC
Site #
AC
MonLoc1
4.6
Control
1,7
MonLoc2
5.3
Coliforms
Increased levels of fecal coliforms may provide a warning of contamination with
pathogens due to contact with fecal matter found in sewage run-off which may include
contact with the fecal material of humans or other animals. Fecal coliform enters the
Simpson Bay Lagoon Mainly through human sewage, either from runoff or direct
seepage or introduction from sceptic holding tanks.
Some waterborne pathogenic diseases that may coincide with fecal coliform
contamination include ear infections, dysentery, typhoid fever, viral and bacterial
gastroenteritis, and hepatitis A. The presence of fecal coliform tends to affect humans
more than it does aquatic creatures, though not exclusively and can still be harmful to
the environment. Aerobic decomposition of this material can reduce dissolved oxygen
levels if continuously entered into the environment. This may reduce the oxygen level
enough to kill fish and other aquatic life. The unit of measurement which was used
during this study was related to a simple Presence/Absence (P/A) scale, with a
positive test having a P-vale and a negative test an A-value.
Site #
P/A
Site #
P/A
MonLoc1
A
Control
P
MonLoc2
A
25
Summary and Conclusion
Summary of water quality testing results
Site #
No
Po
NH3
O
pH
Temp
Sal. PPT
AC
Col. P/A
Site #
No
Po
NH3
O
pH
Temp
Sal. PPT
AC
Col. P/A
14
.6 ppm
.4 ppm
.4 ppm
.7 ppm
8
26
34.7
4.6
A
53
.2 ppm
.2 ppm
.4 ppm
.2 ppm
26 C
26 C
34.8
1,7
P
15
.5 ppm
.4 ppm
.3 ppm
5.5 ppm
8.0
26
34.7
4.6
A
If Results from the monitored locations of the proposed site are compared to the
control site a marked variation in water quality is established, in particular the
presence of coliform and nitrates and phosphates which is a clear indicator of
sewerage in the water.
The results show that although impacted, the monitored locations represent an area
which still has an intact ecosystem and which can still support the ecosystem functions
within the Simpson Bay Lagoon.
Significance of Monitored Areas: Mangroves
For the purposes of this study the figures included are based on those outlined in the
United Nations Environment Program (UNEP) World Conservation Monitoring Center.
2006 document. In the front lines: shoreline protection and other ecosystem services
from mangroves. This report has estimated the total economic value of mangroves at
US$900.000 per square kilometre per annum. This is a lower estimate and the actual
value may indeed be much more significant. This estimate includes the value that
mangroves have for fisheries, tourism and shoreline protection.
SHORELINE PROTECTION
Mangroves naturally form barriers and thus inevitably provide some shore protection, a
fact long recognized by coastal communities, fishers and vessels which use the
sheltered waterways behind these ecosystems. Mangroves can themselves be
26
damaged by strong winds and waves, and so their buffering capacity is a balance
between their resilience and their vulnerability. The current consensus is that:

Mangroves play an important role in shore protection under normal sea conditions and
during hurricanes and tropical storms.

At least 70-90 per cent of the energy of wind generated waves is absorbed, depending
on how healthy these ecosystems are and their physical and ecological
characteristics.
Due to the significant water movement caused during storms within the Mullet Pond
Area, the shoreline protection function of the mangroves allow for a buffering from high
levels of water overflow into the adjacent properties and roadways saving millions of
dollars in infrastructural repairs which would have been necessary if the strands were
removed, thus also contributing to economic stability as part of the recovery after a
natural disaster.
Based on the UNEP Report mentioned above, the Value of the 880 square meters of
Mangrove Habitat which represents the Monitored ecosystem is equal to USD
$792,000 per year in its intact form, not counting or taking into consideration the
high biological value that the area represents. This number is high considering the
relatively small area which was surveyed. If further expansion of the area is taken into
account and if protection is enacted the number will increase exponentially.
Conclusion and Recommendation
The St. Maarten Nature Foundation, in response to reports regarding the filling in of a
significant portion of the Simpson Bay Lagoon for the building of a sewage treatment
plan, conducted ecological monitoring and Environmental Impact Assessments of the
proposed area in order to determine how diverse and rich the area is in terms of
biodiversity such as fish life, mangroves and seagrasses. The results of this study
were then compared to another site in the Simpson Bay Lagoon which has been
known to have less water quality and which was also a proposed site for a possible
sewage treatment plan.
The Nature Foundation recognizes and supports the need for the establishment of a
sewage treatment plan in the area to urgently address the introduction of sewage in
the country’s largest and most important wetland, the Simpson Bay Lagoon. During
patrols in the Lagoon and during water quality tests which are carried out frequently
the Foundation has established scientifically that sewage entering into the lagoon is a
serious issue and is affecting the health, biodiversity and economic value of an area
which is of utmost importance to St. Maarten. The constructing of a Sewage Treatment
Plan, together with proper law enforcement and follow-up, will contribute to the
reduction of waste water entering into the Lagoon.
However, the Nature Foundation, as a conservation management organization, on its
own volition and without being requested to do so, thought it crucial to conduct a
scientific study of the area proposed in order to gauge the impact the filling in of a
significant area of the Lagoon will have on the biodiversity of the Simpson Bay
Lagoon. Over the course of ten days research was conducted in order to determine
what the area looks like and make a recommendation based on established scientific
methods and not on emotion or guesswork.
27
The research conducted by the Nature Foundation clearly shows that the proposed
area is of a high biological value both above the water; in terms of mangrove density
which provides important wetland habitat for birds and provides shelter during
inclement weather such as hurricanes; and under water in terms of significant habitat
for seagrasses, which are severely threatened in the Simpson Bay Lagoon as well as
species of fish and invertebrates which are relatively abundant in the area.
Based on the conducted research the Nature Foundation is also concerned regarding
the flow of water in the Simpson Bay Lagoon and how subsequent filling will affect this.
The increase in algal blooms, some which may be harmful to human health, can occur
if the water dynamics in the Lagoon are drastically changed through increased filling.
Taking these considerations into account, and based on the results of the conducted
research and monitoring, the Nature Foundation cannot give a scientifically backed
positive advice on using the proposed area as the most suitable location for the
construction of a sewage treatment plant for the Cole Bay/ Simpson Bay area.
The Nature Foundation, as appointed Ecosystem Authority for St. Maarten, looks
forward to constructive dialogue backed by suggestions grounded in scientific
research and monitoring, for the solving of the waste water issue in the Simpson Bay/
Cole Bay Area and is, as always prepared to advice and recommend management
options for environmental issues facing St. Maarten.
28