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Blue Ventures Belize Science Training Guide: Invasive Lionfish Monitoring & Research 2013
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Contents
Chapter 1. THE NATURAL HISTORY OF BELIZE .................................................................................... 4
1.1. A brief paleological history ...................................................................................................... 5
1.2. Modern Climate ....................................................................................................................... 5
1.3. Conservation Importance of Belize ......................................................................................... 6
1.4. Bacalar Chico Marine Reserve and National Park (BCMRNP).................................................. 6
Chapter 2. BLUE VENTURES CONSERVATION AND THE BELIZE PROJECT ........................................... 8
2.1. Blue Ventures Conservation .................................................................................................... 8
2.2. Belize Project ........................................................................................................................... 8
2.3. Sarteneja: An Opportunity to Affect the Entire Coastline of Belize ........................................ 9
2.4. Conservation through Collaboration and Partnership .......................................................... 10
The Sarteneja Alliance for Conservation and Development (SACD) ........................................... 10
Wildtracks .................................................................................................................................... 10
Corozal Sustainable Future Initiative (CSFI) ................................................................................. 11
The Belize Fisheries Department ................................................................................................. 11
The Belize Forest Department ..................................................................................................... 11
World Wildlife Fund (WWF) ......................................................................................................... 11
University of Belize ...................................................................................................................... 11
Chapter 3. INTRODUCTION TO CORAL REEFS ................................................................................... 12
3.1. Coral Reefs ............................................................................................................................. 12
3.2. Structure of Corals Reefs ....................................................................................................... 12
3.3. Where Reefs Exist .................................................................................................................. 12
3.4. Ecosystem Interactions .......................................................................................................... 13
Coral Reefs ................................................................................................................................... 13
Sea grasses ................................................................................................................................... 13
Mangroves ................................................................................................................................... 13
Chapter 4. DISTURBANCES TO CORAL REEFS.................................................................................... 14
4.1. Storms and Cyclones .............................................................................................................. 14
4.2. Coral Bleaching ...................................................................................................................... 15
4.3. Nutrient Enrichment .............................................................................................................. 15
4.4. Overfishing and Destructive Fishing Practices....................................................................... 16
4.5. Anchor and Diver Damage ..................................................................................................... 16
Chapter 5. INVASIVE LIONFISH: A NEW THREAT TO BELIZE’S REEFS ................................................ 16
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5.1. Current Knowledge and Remaining Questions...................................................................... 17
Lionfish and Native Fish Recruitment .......................................................................................... 18
Competition, Biotic Resistance and the Potential for Biocontrol ................................................ 18
5.1. Lionfish Monitoring and Research in Bacalar Chico .............................................................. 19
Species List ................................................................................................................................... 20
Chapter 6. MEGAFAUNA ................................................................................................................... 20
6.1. Marine Mammals................................................................................................................... 20
West Indian Manatee (Trichechus manatus)............................................................................... 20
Methodology................................................................................................................................ 22
Bottlenose Dolphin (Tursiops truncates) ..................................................................................... 22
Atlantic Spotted Dolphin (Stenella frontalis) ............................................................................... 23
6.2. Marine Reptiles ...................................................................................................................... 23
Marine turtles .............................................................................................................................. 23
Hawksbill Turtle (Eretmochelys imbricate).................................................................................. 24
Green Turtle (Chelonia mydas) .................................................................................................... 25
Loggerhead Turtle (Caretta caretta) ............................................................................................ 25
Leatherback Turtle (Dermochelys coriacea) ................................................................................ 26
6.3. Crocodiles............................................................................................................................... 26
American Saltwater Crocodile (Crocodylus acutus) .................................................................... 26
6.4. Elasmobranchs (sharks and rays)........................................................................................... 27
Bull Shark (Carcharhinus leucas) .................................................................................................. 27
Caribbean Reef Shark (Carcharhinus perezi) ............................................................................... 27
Nurse Shark (Ginglymostoma cirratum) ...................................................................................... 28
Blacktip Shark (Charcharhinus limbatus) ..................................................................................... 28
Whale Shark (Rhincodon typus)................................................................................................... 29
Tiger Shark (Galeocerdo cuvier)................................................................................................... 29
Great Hammerhead Shark (Sphyrna mokarran) .......................................................................... 30
Scalloped Hammerhead Shark (Sphyrna lewini).......................................................................... 30
Caribbean Stingray (Himantura schmardae) ............................................................................... 31
Southern Stingray (Dasyatis Americana) ..................................................................................... 31
Longnose/Atlantic Stingray (Dasyatis Sabina) ............................................................................. 32
Spotted Eagle Ray (Aetobatus narinari)....................................................................................... 32
Table of Figures
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Figure 1-1 Hawksbill turtle ..................................................................................................................... 6
Figure 1-2 Map of Bacalar Chico National Park and Marine Reserve.................................................... 7
Figure 2-1 Map of Sarteneja (Image from Google Earth, February 2010)............................................. 9
Figure 5-1 Invasive lionfish threaten Belize’s fisheries and reef health .............................................. 16
Figure 5-2 Cocoa damselfish, and many other small damselfish species, are aggressively territorial.
.............................................................................................................................................................. 18
Figure 5-3 Green morays have been nominated as a predator for lionfish, despite studies showing
that lionfish venom can be fatal for fish. ............................................................................................. 18
Figure 5-4 The red hind, a small grouper, has similar prey and shelter requirements to lionfish. It is
likely that they directly compete for resources................................................................................... 19
Figure 6-1 West Indian manatee (maximum 3.5 m) ............................................................................ 21
Figure 6-2 External features of West Indian manatee......................................................................... 21
Figure 6-3 Bottlenose dolphin (maximum 3 m) ................................................................................... 22
Figure 6-4 Atlantic spotted dolphin (maximum 2.5 m) ....................................................................... 23
Figure 6-5 Turtle identification guide .................................................................................................. 24
Figure 6-6 Hawksbill turtle (maximum 1.2 m) ..................................................................................... 25
Figure 6-7 Green turtle (maximum 1.5 m)........................................................................................... 25
Figure 6-8 Loggerhead turtle (maximum 2 m)..................................................................................... 26
Figure 6-9 Leatherback turtle (maximum 1.8 m) ................................................................................. 26
Figure 6-10 American saltwater crocodile ........................................................................................... 27
Figure 6-11 Bull shark (maximum 4 m) ................................................................................................ 27
Figure 6-12 Caribbean reef shark (maximum 3.5 m) ........................................................................... 28
Figure 6-13 Nurse shark (maximum 4.5 m) ......................................................................................... 28
Figure 6-14 Blacktip shark (maximum 3 m) ......................................................................................... 29
Figure 6-15 Whale shark (maximum 15 m) ......................................................................................... 29
Figure 6-16 Tiger shark (maximum 8 m) .............................................................................................. 30
Figure 6-17 Great hammerhead shark (maximum 6 m) ...................................................................... 30
Figure 6-18 Scalloped hammerhead shark (maximum 5 m)................................................................ 31
Figure 6-19 Caribbean stingray (maximum 1.2 m) .............................................................................. 31
Figure 6-20 Southern stingray (maximum 2 m) ................................................................................... 32
Figure 6-21 Atlantic stingray (maximum 70 cm).................................................................................. 32
Figure 6-22 Spotted eagle ray (maximum 2.5 m) ................................................................................ 32
Chapter 1.
THE NATURAL HISTORY OF BELIZE
Belize lies in the western Caribbean and is bordered to the north by Mexico, to the west and south
by Guatemala and to the east by the Caribbean Sea. It is a small country, only covering 23,000
square kilometres, but for its size boasts a wide biodiversity and cross section of habitats. The
population is also small at only 300,000 people. However, largely due to immigration, the
population is rapidly expanding and with the majority of population centres being on the coast, fast
development is having an impact.
Belize has a diverse range of environmental conditions supporting a number of terrestrial and
marine ecosystems. The region consists of the extensive Maya mountains, swampy lowlands in the
north and coastal plains in the south, with tropical forest, mangroves and coral reefs all in close
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proximity. The climate and habitat promote biodiversity with numerous terrestrial species of flora
and fauna and a high diversity of marine species. The coastline is lined with coral reef and sandy
island formations called cayes.
The 320 km long Belize Barrier Reef, forms the heart of the Mesoamerican Barrier Reef System –
the largest barrier reef in the western hemisphere and the second largest in the world. The
diversity and quality of the reef have led to the reef being considered one of the seven wonders of
the underwater world (http://www.7wonders.org/underwater-wonders/).
Coastal lagoons and mangroves cover much of the coastline, providing ideal breeding grounds and
habitat for juvenile species, as well as the home to the charismatic Antillean manatee, classified as
“Endangered” by the IUCN Red List. Combined, these factors make the Belize coastal region one of
great ecological value and importance.
1.1.
A brief paleological history
25 million years ago, the Cocos tectonic plate began to move and slide under the Caribbean plate.
This movement resulted in large-scale volcanic activity, with magma chambers erupting from the
sea floor. These slowly grew to form an archipelago of submarine volcanoes, between Panama and
Guatemala, eventually leading to the formation of islands. Sediment and rock from North and
South America slowly deposited between the islands, finally coalescing approximately 3 million
years ago to form a continuous, narrow, landmass between the two: Central America.
The formation of Central America altered the flow of water between the Pacific and Atlantic
Oceans, forcing Atlantic water north and resulting in the formation of the Gulf Stream. The
development of a land bridge between North and South America played a key role in facilitating
biotic exchange between the two regions, allowing the expansion of animal and plant species’
ranges.
The result has been that Belize has biotic features of both North and South America further leading
to an impressively rich biodiversity.
1.2.
Modern Climate
Located south of the Tropic of Cancer, Belize has a tropical climate, with gentle breezes and golden
sunshine for much of the year, as well as distinct windy, wet and dry seasons. Temperatures are
dependent upon elevation, proximity to the coast and the subsequent effects of the north-east
trade winds from the Caribbean Sea. The annual mean temperature is 26°C (79°F), with 85%
humidity. Sea surface temperatures (24-28°C / 75-84°F) are ideal for coral reef formation.
Blue Ventures research site is based in the north of Belize. The northern region receives the lowest
annual rainfall, an average of 127 cm per year. The Norte season, characterised by cool, northerly
winds, occurs from November to February, followed by the dry season (March to June). The wet
season occurs during the summer months, from July to October. Belize’s hurricane season is from
June to October, however a ‘direct hit’ has not been experienced since 2000.
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A wide range of habitats is found in Belize: tropical forest (60% of Belize remains forested), lowland
savannahs and the Maya mountains inland, lagoons, mangrove, and littoral forest along the coast,
and coral cayes and the majestic barrier reef offshore.
1.3.
Conservation Importance of Belize
The Belize Barrier Reef System (BBRRS), a UNESCO World Heritage Site (WHS), forms the core of the
Mesoamerican Barrier Reef System (MBRS). The area was originally nominated because of its great
biodiversity, which provides habitat to a number of species of conservation concern. However,
growing threats from climate change and direct human impacts have resulted in decreasing general
reef health and declines in fish stocks, leaving the system vulnerable to further deterioration if
there is no immediate action to mitigate these threats. The BBRRS-WHS is now listed as a World
Heritage Site in Danger.
1.4.
Bacalar Chico Marine Reserve and National Park (BCMRNP)
BCMRNP was established in 1996 as the result of lobbying by local fishermen from the village of
Sarteneja, the largest fishing community in Belize and mainland site for Blue Ventures. It is hoped
that by incorporating these local communities into conservation initiatives, the chance of long-term
success of the reserve can be greatly increased.
Blue Ventures Bacalar Chico Dive Camp (BCDC) is
located in Bacalar Chico Marine Reserve (BCMR) on
Ambergris Caye. It houses to a number of species of
international concern, including the charismatic
Antillean manatee, critically endangered hawksbill
turtle (Figure 1-1) and goliath grouper, Yucatan
endemics, such as the increasing threatened black
cat bird, and critically endangered staghorn and
elkhorn corals (Acropora palmata, A. cervicornis).
Figure 1-1 Hawksbill turtle
Much of the wildlife in Bacalar Chico resembles the Yucatan endemics, with 187 bird, 40
mammalian, 55 reptilian and 22 amphibian species. The expansive Cantena Lagoon contains small
mangrove cayes, providing important breeding grounds for marine and coastal birds, while the
mangrove roots provide nursery grounds for reef fish. The sandy beach provides an important
nesting site for loggerhead and green turtles.
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Figure 1-2 Map of Bacalar Chico National Park and Marine Reserve.
BCMR is also a key part of an international system of connected MPAs (Figure 1-2); Arrecife de
Xcalak in Mexico borders the Preservation Zone (northern BCMR), and Corozal Bay Wildlife
Sanctuary borders BCMR at Deer Caye, to the east. In turn, Corozal Bay Wildlife Sanctuary is
connected to Sanctuario Del Manati in Chetumal Bay, Mexico. Imminent plans to extend the
management area of Hol Chan Marine Reserve will further increase connectivity between these
sites.
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Chapter 2. BLUE VENTURES CONSERVATION AND THE BELIZE
PROJECT
2.1.
Blue Ventures Conservation
Blue Ventures’ mission is to encourage the sustainable use of marine resources in order to conserve
tropical coastal habitats, through working with coastal communities in developing countries to help
them build the skills and knowledge they need to protect the marine environments on which their
livelihoods depend.
2.2.
Belize Project
In Belize, Blue Ventures operates in two areas, working towards one goal: science-led, ecosystembased management, enabling long-term use of Belize’s coastal and marine resources.
We do this through research and monitoring of MPAs, education and outreach with stakeholder
communities and international volunteers, promotion of sustainable, alternative livelihoods, often
through the development of innovative, market-driven solutions, and collaboration with national
and international bodies.
Sarteneja is the largest fishing community of Belize, with 80% of households directly dependent
upon fishing as their primary source of income. It sits on the shores of Corozal Bay Wildlife
Sanctuary (CBWS), designated for the protection of the endangered Antillean manatee, but also
supporting an active bull shark nursery, bird nesting habitat, extensive mangroves, and an artisanal
fishery. In Sarteneja, collaboration with schools, resource managers and users aim to increase
awareness of environmental threats and participation in the development and management of
target species and habitats. Blue Ventures’ office in Belize is located in Sarteneja.
Bacalar Chico is one of seven MPAs forming the UNESCO World Heritage Site. There is no
community directly adjacent to the protected area, which is primarily used for tourism from San
Pedro, and a limited amount of fishing from Sartenejan and San Pedrano fishers. Blue Ventures
established its coral reef monitoring programme in Bacalar Chico as it was recognised to be a
relatively data deficient portion of the Belize Barrier Reef. Blue Ventures’ research and dive camp
(BCDC) is in BCMR.
In Belize, through volunteer assistance, Blue Ventures aims to:
•
•
•
Further coastal conservation in BCMR and CBWS, and contribute to wider conservation
efforts in Belize and the Mesoamerican Barrier Reef System (MBRS).
Assist coastal communities in improving marine resource management and conservation
efforts.
Provide technical assistance for the effective monitoring and management of MPAs in
Belize.
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•
•
Build capacity for local management of resources, through primary, secondary and tertiary
educational programmes.
Promote integration into sustainable alternative livelihoods and fishery target species, such
as the invasive lionfish.
2.3.
Sarteneja: An Opportunity to Affect the Entire Coastline of Belize
The village of Sarteneja, population 3000, is located along the coast of Corozal Bay (Figure 2-1). This
shallow bay in the north of the country hosts a broad diversity of habitats including estuaries,
mangroves and seagrass beds. It is bound by the Mexican mainland to the north, Belizean mainland
to the west and Ambergris Caye, a southerly extension of the Yucatan peninsula, to the east. In the
south, the bay empties into the wide reef flats of Belize, which in turn drain to the Caribbean Sea.
This protected bay affords the fishermen of Sarteneja a sheltered launching point for their boats,
with which they harvest fish, lobster and conch from the entire length of the Belizean coast.
Figure 2-1 Map of Sarteneja (Image from Google Earth, February 2010).
Until the 1950s the small village of Sarteneja was a largely agricultural community, with a tradition
for wooden sailboat building due to an historical use of Sarteneja as a trading post. However, a
direct hit from Category 5 Hurricane Janet in 1955 destroyed houses, crops and contaminating the
soil with salt. In the aftermath the village was rebuilt with the hurricane-resistant concrete
structures that remain today, and the villagers turned from their ruined fields to a new lucrative
export market for seafood that had opened for lobster and conch.
Sarteneja’s characteristic wooden sailboats access all portions of the Belize Barrier Reef System, as
far south as the Sapodilla Cayes, near the Guatemalan border. They a familiar sight throughout the
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atolls and reefs along the coast, each carrying between 8 and 14 fishermen, who fish by free diving;
gathering conch and lobster by hand, and fish by spear.
For several decades Sarteneja prospered on their newfound industry. However, as the population
and market grew, the inevitable started to happen. The availability of resources began to decline,
whilst the number of fishers continues to increase. Today many fishermen seek work in other areas,
particularly the tourist industry, but jobs are hard to come by, so for many the only option is to fish
longer and harder to try and ensure there is still an income to support their families.
Historically there has been relatively little NGO involvement in the Sartenejan community, despite
the use they make of the marine resources within Belize. One local NGO established in 1990,
Wildtracks, has had a clear impact in Sarteneja and marine resource use throughout Belize, through
their diverse programme responding to terrestrial and marine conservation issues. Further, the
community has started taking steps of its own to provide environmental education and
conservation efforts through the formation of the Sarteneja Alliance for Conservation and
Development (SACD) in the last four years. Blue Ventures is working closely with this communityled NGO to foster greater care of the immediate environment around the Corozal Bay and also
provide education and conservation advice to the fishing community to help manage their marine
resources.
2.4.
Conservation through Collaboration and Partnership
Blue Ventures have developed close links with several local organisations involved in conservation
work, throughout Belize, and specifically around Sarteneja and Bacalar Chico. These partners
include the following:
The Sarteneja Alliance for Conservation and Development (SACD)
Established in September 2008, SACD aims to bring people together to promote conservation and
sustainable development. It is the co-manager of Corozal Bay Wildlife Sanctuary, a responsibility
shared with the Belize Forest Department.
The alliance consists of core SACD staff as well as:
•
•
The Sarteneja Tour Guides Association (STGA), a group aimed at developing the tourism in
the area to alleviate reliance on fishing.
The Sarteneja Fishermen Association (SFA), established to provide Sarteneja’s fishermen
with mechanisms to encourage sustainable alternatives to fishing, reducing their
dependence on fishing.
Wildtracks
Established in 1990, Wildtracks is a multi-faceted non-profit organisation involved in policy-level
advisory, protected area assessment and management, education, outreach and capacity building.
Wildtracks also runs Belize’s only manatee and primate rehabilitation centres.
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Corozal Sustainable Future Initiative (CSFI)
CSFI manages the Shipstern Nature Reserve, a large terrestrial conservation area adjacent to
Sarteneja, encompassing several inland lagoons, large mangrove areas and extensive tracts of
forest.
The Belize Fisheries Department
This governmental department is the responsible for the management of Belize’s aquatic and
marine resources, and is the primary manager of all Belize’s marine reserves. In some areas, the
Belize Fisheries Department (BFD) has developed partnerships with NGOs to jointly manage the
area. BFD is the sole manager of Bacalar Chico, where Blue Ventures conducts extensive ecosystem
and resource monitoring to provide management advise through regular communication and in
annual reports.
The Belize Forest Department
The Forest Department manages Belize’s terrestrial environments and natural resources including
Bacalar Chico National Park and co-management (with SACD) of Corozal Bay Wildlife Sanctuary.
World Wildlife Fund (WWF)
An international NGO that performs site-specific conservation throughout the world and has
extensive experience developing conservation programmes in Belize. WWF, with their history and
experience throughout Central America, provide scientific guidance and advice on operating in
Belize and share information and experiences with other conservation efforts in neighbouring
countries.
University of Belize
This is the principal university within Belize and has a dedicated department for marine
environmental research and tertiary education.
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Chapter 3.
3.1.
INTRODUCTION TO CORAL REEFS
Coral Reefs
Coral reefs comprise less than 0.5% of the ocean floor, an area of 600 000 square miles, yet it is
estimated that more than 90% of marine species are directly or indirectly dependent on them. They
are home to a third of all the species in the ocean and include 4000 coral reef fish species, which
accounts for approximately a quarter of all marine fish species. Coral reefs are the most productive
ecosystems in the marine environment and are also able to fix large amounts of carbon dioxide
making them vital to the future health of the planet.
3.2.
Structure of Corals Reefs
Coral reefs are often called the ‘rainforests of the sea’, and this comparison reflects the enormous
biodiversity that is immediately apparent to anyone who has had first-hand experience of visiting a
coral reef. Coral reef ecosystems are known for their spectacular structures, colours and marine life
that has the greatest diversity per unit area of any marine ecosystem. Coral reefs are unique
ecosystems and they are characterised by high productivity, a great diversity of competitors and a
complex set of interactions between all the species. Although they are rich in biodiversity they are
in fact fragile and it is only through their efficient use of all available nutrients that enable them to
maintain such a high degree of biodiversity in the otherwise nutrient sparse tropical marine waters.
3.3.
Where Reefs Exist
Reef-building corals are restricted in their distribution as a result of the algal-coral symbiotic
relationship. This relationship requires a consistent environment in which the temperature, salinity
and pH remain within a certain band. Therefore coral reef formation requires a sea temperature
that does not fall below 18 °C for any extended period. Most require a salinity that ranges from 32
to 42 parts per thousand, and the water must also be clear to allow sufficient light to penetrate.
The corals’ requirement for high light for photosynthesis also explains why most reef-building
species are restricted to the euphotic (light penetration) zone, approximately up to 70 m in depth.
The number of species of corals on a reef declines with depth, and as the light intensity diminishes
the ability for corals to secrete limestone is reduced.
As a result of these environmental conditions that coral reefs require to develop, they are found
within the 20° surface isotherm, the tropical and semitropical waters. This limits their distribution
to a belt that runs around the earth between 30°o latitude north and south of the equator. The
diversity of reef corals, the number of species, decreases in higher latitudes up to about 30° north
and south, beyond which reef corals are usually not found. The diversity of coral species is also
dependent on the ocean in which they are located. At least 500 reef-building species are known to
exist in the waters of the Indo-Pacific region whereas the Atlantic Ocean contains approximately 62
known species.
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3.4.
Ecosystem Interactions
Seagrass beds and mangrove forests are often important in the success, survival and stability of
coral reefs. The three ecosystems are closely linked and their interactions are often vital in the
continued health of the reef. The structure and function of each of these three ecosystems vary:
Coral Reefs
• Accrete CaCO3 (calcium carbonate)
• Attenuate wave energy, protect shoreline
• Offer refuge and food
• Recycle Particulate Organic Material (POM)
Sea grasses
• Stabilise and bind sediment
• Produce POM and DOM (dissolved organic matter)
• Recycle and export nutrients
• Produce floating leaf litter
• Attenuates storm surges
Mangroves
• Trap sediment
• Reduce wave action
• Buffer salinity changes (from sea and from freshwater runoff)
• Act as a secondary nursery ground for fish and crustaceans
As well as having their own specialised associated organisms, mangroves and seagrass beds are
important nurseries for many species. Juvenile fish, crustaceans, molluscs and echinoderms take
advantage of the safer and more sheltered environment, with fewer predators, that the mangroves
and seagrass beds provide.
A second important function of seagrass beds and mangrove forests in relation to reef health is
their ability to trap the sediment carried in rivers. This sediment discharge may otherwise run the
risk of damaging the reefs by sediment shading or smothering. As the trapped nutrients are broken
down a large volume of the oxygen in the water surrounding the mangroves is used. This results in
the mangroves having a low level of oxygen in the water surrounding them and leaving only a thin
layer of oxygen at the surface available for use by mangrove residents.
Furthermore, mangroves and seagrass beds are extremely important in the stabilisation of the
coastline by providing protection from storm damage and reducing the level of erosion.
Sea grass beds in addition to being nurseries are also used as feeding grounds for megafauna such
as turtles and manatees. They also act as a second stage of filter for any sediments which have not
been trapped in the mangroves, and soak up any excess nutrients that may promote eutrophication
(the proliferation of algae as a result of increased nutrients in the water) out on the reef.
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Regular problems for these habitats are almost exclusively anthropogenic in forms. Mangrove wood
is exceptionally dense and this makes it ideal for charcoal production. It is also a desirable material
for building and so in an area where building materials are scarce they are often exploited. Seagrass
beds are extremely delicate so one of the problems is propeller scarring, where the wash of the
propeller actually destroys the bed, fragmenting it and severely restricting the movements of some
species that live there.
Chapter 4.
DISTURBANCES TO CORAL REEFS
Disturbances to coral reefs can be the result of both natural and anthropogenic hazards and
threats. As human populations and coastal pressures increase coral reefs are becoming more
heavily exploited. Current estimates put 10% of coral reefs as degraded beyond recovery, with a
further 60% predicted to die by 2050 if current pressures and disturbances continue unchecked.
The boundaries between natural and anthropogenic threats have become increasingly blurred as
the effects of natural disturbances are exacerbated by anthropogenic stresses, such as climate
change. Human activities can reduce the resilience of coral reefs and their ability to recover from
disturbances. They can also intensify the effects of natural disturbances, such as increasing the
frequency of disease outbreaks and tropical storms.
4.1.
Storms and Cyclones
Extreme weather is one of the most obvious and major stresses to coral reefs as coral reefs occur in
the tropics, areas that are subjected to severe storms. During storm periods, not only are the
delicate coral skeletons broken, but increased sediment output from land erosion can smother
entire reefs.
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4.2.
Coral Bleaching
Corals and their symbiotic algae, zooxanthellae, are vulnerable to a variety of environmental
stresses that can disrupt the symbiotic relationship and cause bleaching - the loss of the
zooxanthellae and their photosynthetic pigment.
Stresses that can lead to coral bleaching include:
•
•
•
•
•
•
Elevated or decreased sea water temperature
Pollution
Sedimentation
Disease
Increased or decreased light levels
Fresh water flooding
In 1998 a mass bleaching event occurred worldwide and in a report presented to the U.S. Coral Reef
Task Force in 1999, by the U.S. State Department warned: "In 1998 coral reefs around the world
appear to have suffered the most extensive and severe bleaching and subsequent mortality in
modern record. In the same year, tropical sea surface temperatures were the highest in modern
record, topping off a 50-year trend for some tropical oceans. Localised stressors and natural
variability alone cannot account for these events. The geographic extent, increasing frequency, and
regional severity of mass bleaching events are likely a consequence of a steadily rising baseline of
marine temperatures, driven by anthropogenic global warming.
4.3.
Nutrient Enrichment
Nutrient enrichment in coral reefs normally occurs as a result of anthropogenic inputs, such as
sewage, or fertiliser and pesticide runoff. These anthropogenic inputs lead to excesses of nutrients,
nitrates and phosphates, in the water surrounding the coral reefs and can cause eutrophication.
Eutrophication results as the increase in the mineral and organic nutrient levels of the waters
promote a proliferation of plant life, and cause a sudden bloom of algae in the previous nutrient
poor tropical waters. The increase in algae reduces the dissolved oxygen content of the water,
which can lead to the suffocation of marine species. Eutrophication also reduces the turbidity of the
water and decreases the amount of light that can reach the corals. The increase amounts of
nutrients can also enhance the growth of other reef organisms, such sponges and algae, which can
out-compete the slower growing corals for space.
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4.4.
Overfishing and Destructive Fishing Practices
Increasing coastal populations have increased the pressure on marine resources. The majority of
coral reefs also occur in regions of high poverty and this has led to the overfishing and
unsustainable exploitation of fish and invertebrate populations. Overfishing can be particularly
damaging to populations of slow maturing species, such as sharks, groupers and marine turtles.
4.5.
Anchor and Diver Damage
Physical damage to the reef can occur as a by-product of large numbers of people using the reef or
through targeted extraction of items from the reef. Dive boats anchoring repetitively at certain dive
sites can cause huge damage but permanent moorings prevent this. Accidental damage also occurs
as a result of divers who are unable to maintain neutral buoyancy or swim too close to the reef.
Chapter 5.
INVASIVE LIONFISH: A NEW THREAT TO BELIZE’S REEFS
The red lionfish (Pterois volitans, Figure 5-1)was accidentally introduced to the Atlantic in the
1980s. The presence of their numerous venomous spines makes it an unsavoury prey item, with
few species recorded to successfully predate upon lionfish. Feeding on a diversity of juvenile fish
and invertebrates, invasive lionfish impede population growth of ecologically and commercially
significant species through predation and competition, with devastating effects on the marine food
web, particularly apex predators such as sharks.
Figure 5-1 Invasive lionfish threaten Belize’s fisheries and reef health
In North Carolina and the Bahamas, lionfish spawn approximately every four days throughout the
year. The combination of these factors – lack of predatory pressure, generalist diet and high annual
fecundity in the invaded ranges – have enabled the establishment of rapidly growing populations of
lionfish throughout the Caribbean.
Currently, lionfish are considered to be one of the primary threats to Caribbean coral reefs, and
potentially “the most devastating marine invasion in history” (The Sunday Times, 2008). First
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officially recorded in Belize in 2008, the local population has increased rapidly and infiltrated most,
if not all, marine ecosystems nationally.
5.1.
Current Knowledge and Remaining Questions
Specific regional research needs and key questions have been identified by the Gulf and Caribbean
Fisheries Institute, which includes monitoring of lionfish density, native species interactions, and
determining the effectiveness of control efforts.
Due to the relatively recent arrival of lionfish in Belize, there are still a number of questions that
must be answered to enable identification of the local impacts of an established lionfish population
(Table 1). Although there is much discussion of these points within published literature, the
majority of studies are centred on the Florida Keys and Bahamas, with little published research
referring to Belizean or Mesoamerican populations.
Table 1: Based upon GCFI recommendations, literature review, personal consultation with protected areas managers, and analysis
of results from previous surveys, a list of commonly encountered questions and data gaps for Belize have been drafted, providing
a framework for directed research to inform lionfish ecology and management at local, national and regional levels.
Specific Research Questions for Belize
1. What is the current status of lionfish in
Belize?
2.
What are the limits to population
expansion in Belize?
Justification
• National interest in a population census
• Monitor effectiveness of management effort and market
interventions
•
•
3.
4.
Is their reproductive cycle governed by
environmental conditions?
What does their diet consist of, and
does it change spatially or temporally?
•
Formation of targeted removal efforts
•
Long-term downstream impacts on fisheries, food web and
ecosystem interactions
Do observed shifts in diet relate to changes in ecosystem
structure or simply denote ontogenetic or seasonal changes in
foraging patterns for invasive lionfish?
•
5.
Which native species compete directly
with lionfish for common resources?
•
•
6.
Do any native species prey upon
lionfish, with no negative affect to their
health?
Managers of coastal protected areas interest in status and
potential of invasion in non-reef environments
Long-term downstream impacts on fisheries, food web and
ecosystem interactions
•
•
•
Long-term downstream impacts on fisheries, food web and
ecosystem interactions
Explore potential biotic resistance of reefs to invasive lionfish
Long-term downstream impacts on fisheries, food web and
ecosystem interactions
Explore potential biocontrol and biotic resistance of reefs to
invasive lionfish
Form official recommendations for Belize (e.g. guidelines on
feeding native predators)
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Lionfish and Native Fish Recruitment
Invaded reefs display significantly lower fish recruitment rates than un-invaded reefs. Lionfish are
known to feed on a diversity of fish families and invertebrates, including individuals almost half of
their total length. Therefore, lionfish population structure, including size class frequency, affects the
susceptibility of native species to predation. Blue Ventures’ stomach content analysis indicates that
lionfish in Bacalar Chico may be shifting from a fish-dominated to an invertebrate-dominated diet.
To investigate fish recruitment impacts in Bacalar
Chico, it is important to determine the density of
not only lionfish and fish recruits, but also other
species known to decrease fish, recruit populations.
These are primarily comprised of territorial
damselfish.
Figure 5-2 Cocoa damselfish, and many other small
damselfish species, are aggressively territorial.
Competition, Biotic Resistance and the Potential for Biocontrol
One study suggests that populations of predatory fish, such as large-bodied grouper may have the
potential to be a biocontrol for invasive lionfish, either through competition or predation. In
contradiction to this, a recent Caribbean-wide study shows no relationship between predatory fish
and invasive lionfish biomass on reefs.
Predation
Lionfish’s natural defence against predation is substantial: envenomation is sufficiently toxic to
result in mortality in many fish species, there are few known predators on lionfish in their native
ranges, and in captivity groupers displayed significant avoidance to lionfish, even during periods of
starvation.
Nevertheless, certain native fish species have been nominated as potential predators of lionfish:
1. Sharks (all species)
2. Moray Eels (all species)
3. Large-bodied grouper
a. Nassau (Epinephelus striatus)
b. Goliath (E. itajara)
c. Black (Mycteroperca bonaci)
d. Yellowfin (M. venenosa)
e. Yellowmouth (M. interstitialis)
f. Tiger (M. tigris)
Figure 5-3 Green morays have been nominated as a predator
for lionfish, despite studies showing that lionfish venom can
be fatal for fish.
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Competition
Competition between lionfish and large-bodied grouper is unlikely, given differences in prey.
Lionfish do compete with native piscivores and invertivores, such as small-bodied grouper and
lobster, for food and space. Prey in the Atlantic have no experience of lionfish as a predator, nor do
they recognise lionfish’s predation strategy (flared fins used to corner fish); this may explain why
lionfish have significantly higher consumption rates than native small-bodied predators.
Direct competitors of invasive lionfish in the Atlantic are considered to be:
1. Lobster
a. Caribbean spiny (Panulirus argus)
b. Spotted spiny (P. guttatus)
4. Small-bodied grouper
a. Immature Nassau (Epinephelus striatus)
b. Immature goliath (E. itajara)
c. Red Hind (E. guttatus)
d. Immature black (Mycteroperca bonaci)
e. Immature yellowfin (M. venenosa)
f. Immature tiger (M. tigris)
g. Immature yellowmouth (M. interstitialis)
h. Coney (Cephalopholis fulva)
i. Graysby (C. cruentatus)
5. Snappers (not cited as competitors in literature, but have similar prey to lionfish).
Figure 5-4 The red hind, a small grouper, has similar prey and shelter requirements to lionfish. It is likely that they directly compete
for resources.
5.1.
Lionfish Monitoring and Research in Bacalar Chico
Surveys take place at dive sites throughout BCMR, representing variety of habitat types, fished and
un-fished areas, and across three depth ranges: Backreef (1-5m), Forereef Shallow (8-15m) and
Forereef Deep (18-25m).
Monitoring methods include a Lionfish Focussed Search, which counts, measures and records
behaviour of lionfish within a defined area, and a modified fish belt, specifically looking at fish
recruits, territorial damselfish, shark, moray eel, snapper, grouper and lobster abundance.
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Species List
Territorial Damselfish
Beaugregory
Cocoa Damsel
Dusky Damsel
Longfin Damsel
Threespot Damsel
Snapper
Schoolmaster
Grey Snapper
Mahogany Snapper
Mutton Snapper
Lane Snapper
Cubera Snapper
Dog Snapper
Yellowtail Snapper
Other Damselfish
Bicolour Damsel
Yellowtail Damsel
Blue Chromis
Brown Chromis
Sergeant Major
Moray Eel
Chain Moray
Green Moray
Spotted Moray
Goldentail Moray
Great Barracuda
Chapter 6.
6.1.
Grouper
Black Grouper
Tiger Grouper
Goliath Grouper
Yellowmouth Grouper
Yellowfin Grouper
Nassau Grouper
Red Grouper
Graysby
Coney
Red Hind
Lobster
Caribbean Spiny Lobster
Spotted Spiny Lobster
MEGAFAUNA
Marine Mammals
West Indian Manatee (Trichechus manatus)
The West Indian manatee (Figure 6-1) is the largest species of manatee. The species is subdivided
into Florida (T. m. latirostris) and Antillean (T. m. manatus) manatees. The IUCN Red List
categorized the species as “vulnerable” and both subspecies as “endangered”. West Indian
manatees inhabit rivers, lakes, lagoons, and coastal marine environments from south-eastern North
America to north-eastern South America, including Central America and the Caribbean. The
population in Belize has been estimated at around 800 individuals. There are concerns that
fragmentation of this population from the population in Florida, due to overharvesting in Mexico,
may lead to inbreeding and a decrease in genetic diversity, further threatening the future of this
species. Manatees are long-lived herbivorous marine mammals feeding primarily on the sea grass.
As an adaptation to that their digestive system is relatively very long (20 m), taking the ingested
material about seven days to pass through. Because manatees feed in the water, they exclude the
water from the food when they swallow, making the contents of their stomach relatively dry.
However, just as the terrestrial herbivores, manatees also possess large salivary glands (for
lubrication and initial digestion of food).
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Figure 6-1 West Indian manatee (maximum 3.5 m)
Adult West Indian manatees can reach a length of 3.9 m (about 13 ft) and a weight of 1,500 kg
(3,500 pounds). However, the Antillean subspecies tends to be slightly smaller than the Floridian
representative. Newborn calves generally range from 80 to 160 cm (2.6 ft to 5.2 ft) long and weigh
approximately 30 kg (70 pounds). The lifespan of the manatee is not known with certainty;
however, the research conducted to date suggests that the maximum age is around 60 years.
Females and males are very similar in size and appearance although the former may be somewhat
more robust than the latter. The skin is rough and generally gray to brown in colour, although the
colour varies with age (newborns are darker) and the amount and type of epiphytic growth (such as
algae).
The eyes are small and no external ear is present. They have a large head with mobile lips covered
in bristles and a paddle shaped tail, which is easily spotted when making a circular ripple on the
surface of the water. Nostrils are located on the tip of the snout, and muscular valves open and
close them as the animal surfaces and dives. Manatee’s mammary glands and teats (one per side)
are located behind the forelimbs (Figure 6-2). The milk glands have no storage sacs so manatee
calves have to feed frequently at short intervals.
Figure 6-2 External features of West Indian manatee
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Major threats to survival of the species include habitat degradation and loss, illegal hunting, boat
strikes, entanglement in fishing gear, entrapment in water control structures, pollution, disease,
and human disturbance.
Methodology
Manatee surveys will be conducted in Corozal Bay Wildlife Sanctuary (CBWS) as well as in Bacalar
Chico Marine Reserve (BCMR). Current CBWS manatee surveys are conducted in the mornings,
consisting of 30 min observations of already identified resting holes from the boat. If manatee is
observed, its size and behaviour is recorded. We also record a set of environmental data such as
weather condition, salinity, etc. Also any opportunistic observations of the manatees on the way to
the resting holes and back are recorded.
During the BCMR manatee surveys our data collection will extend beyond only environmental data
and observations from the boat. Equipped with the underwater camera we will record the animals
underwater in order to identify separate individuals inhabiting BCMR. This methodology is called
photo identification and it is often used by scientists to study marine mammals. The research
conducted is aiming towards identifying their behaviour, habitat preference and usage, their
movement patterns and finally the abundance and connectivity of the manatee population of
BCMR.
Bottlenose Dolphin (Tursiops truncates)
Bottlenose dolphins (Figure 6-3 Bottlenose dolphin) are a light blue to slate grey colour, with a paler
underside. They are the most commonly sighted dolphin species in BCMR. They have a
pronounced beak and a rounded forehead. Bottlenose dolphins can be distinguished from the
Atlantic spotted dolphin by their slightly hooked, tall dorsal fin and lack of spots on their body. They
are also on average larger in size than the Atlantic spotted dolphins. They are normally found in
small groups. Just as with manatees, photo identification is a commonly used methodology to study
them in the wild.
Figure 6-3 Bottlenose dolphin (maximum 3 m)
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Atlantic Spotted Dolphin (Stenella frontalis)
The Atlantic spotted dolphin (
Figure 6-4) is smaller in size than the bottlenose dolphins. They are a grey to black colour with pale
spots. Atlantic spotted dolphins are nearly always in large groups.
Figure 6-4 Atlantic spotted dolphin (maximum 2.5 m)
6.2.
Marine Reptiles
Marine turtles
All species of marine turtles are classified by the IUCN as vulnerable, endangered or critically endangered because of the
overharvesting of their eggs, accidental death via bycatch and boat traffic, direct exploitation of adults for their meat and shell,
and habitat and nesting disruption. The most accurate clues for identification are the patterns on the top of their shells (
Figure 6-5
Figure 6-5). The shell is made up from central/bridge plates (large plates running down the centre
of the shell), costal plates (a single row of plates paralleling each side of the central plates) and
scutes (small plates on the shells edge. The size of the tail on a turtle can be used to identify its sex.
A male turtle will have a tail longer than its rear flippers, whilst a female turtle will have a tail
shorter than its rear flippers. Among the turtle species observed on the reef and in the open waters
of BCMR, only Green and Hawksbill turtle have also been found in the mangroves.
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Figure 6-5 Turtle identification guide
Hawksbill Turtle (Eretmochelys imbricate)
The hawksbill turtle (Figure 6-6) has an overhanging upper beak (hence the name hawksbill),
though this should not be used as the sole feature for identification. One of the most commonly
sighted turtles in Bacalar Chico, seen both on the forereef and backreef and the mangroves. They
can be accurately distinguished from the green turtle by the two pairs of scales between their eyes.
They have brown shells, with yellow-brown fan like markings. The rear border plates on a
hawsksbill turtle have a serrated edge, and the shell plates overlap.
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Figure 6-6 Hawksbill turtle (maximum 1.2 m)
Green Turtle (Chelonia mydas)
Green turtles (Figure 6-7) have brown shells with olive shade, which gives them a chequered
pattern. They have only one pair of scales between the eyes, distinguishing them from the
hawksbill turtle. The shell plates of a green turtle do not overlap and the margin of the carapace is
not serrated. Green turtles are the third most commonly sighted turtles in Bacalar Chico, however
they are the species most commonly observed in the mangroves.
Figure 6-7 Green turtle (maximum 1.5 m)
Loggerhead Turtle (Caretta caretta)
Loggerhead turtles (Figure 6-8) are the second largest marine turtle. They are second most
commonly observed marine turtle species in Bacalar Chico. The distinguishing features for
loggerhead turtles are large blunt head and powerful jaws, steeply domed carapace with a reddish,
brown shell and 5 rarely 6 pairs of lateral shell plates.
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Figure 6-8 Loggerhead turtle (maximum 2 m)
Leatherback Turtle (Dermochelys coriacea)
Leatherback turtles (Figure 6-9) are the largest marine turtle. They possess no shell plates; instead
their back is covered by tough leather like skin, allowing them to dive to great depths. They are also
the only marine turtle to thermoregulate, enabling them to visit any of the world’s oceans.
Figure 6-9 Leatherback turtle (maximum 1.8 m)
6.3.
Crocodiles
American Saltwater Crocodile (Crocodylus acutus)
American Saltwater crocodile (Figure 6-10) is the largest crocodilian found in the Western
hemisphere. Average length of the species is 3.4 m, with maximum of 7 m. They have excellent
night vision, enabling them to hunt at night. Their diet consists of fish as well as occasionally crabs,
turtles, mammals and birds. Their prefered habitats are saltwater lagoons, channels and
mangroves; making BCMR ideal home for the species. They are listed as vulnerable on the IUCN list.
The species was historically hunted for skins (bags and shoes etc.) and is currently most threatened
by habitat loss due to coastal development.
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Figure 6-10 American saltwater crocodile
6.4.
Elasmobranchs (sharks and rays)
Bull Shark (Carcharhinus leucas)
The bull shark (Figure 6-11) is a stocky, heavy bodied shark. They have a short, blunt, rounded
snout and small eyes. Bull sharks have a large triangular, pointed first dorsal fin with a wide base.
Corozal Bay is a nursery ground for bull sharks.
Figure 6-11 Bull shark (maximum 4 m)
Caribbean Reef Shark (Carcharhinus perezi)
The Caribbean reef shark (Figure 6-12) has a grey upper half of its body, with a fading white
underside. They have a sharply pointed first dorsal fin and long, narrow pectoral fins.
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Figure 6-12 Caribbean reef shark (maximum 3.5 m)
Nurse Shark (Ginglymostoma cirratum)
The nurse shark (Figure 6-13) is the most commonly seen shark in Bacalar Chico. Often seen on the
sandy floor beside coral bommies and under overhangs, they are able to actively pump water over
their gills. Nurse sharks have barbels on their snout and flattened bellies, optimised for feeding on
benthic invertebrates. They have a low front dorsal fin and second dorsal fin of equal size.
Figure 6-13 Nurse shark (maximum 4.5 m)
Blacktip Shark (Charcharhinus limbatus)
The blacktip shark (
Figure 6-14) is distinguished by black edging on its pectoral, ventral, dorsal and caudal fins, though
this fades to indistinct with age. A second distinguishing feature is the presence of a white streak
on its flank, extending from the caudal peduncle, above the anal fin and toward the centre of the
body. They also have a pale to white anal fin.
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Figure 6-14 Blacktip shark (maximum 3 m)
Whale Shark (Rhincodon typus)
The whale shark (Figure 6-15) is the largest fish in the sea. They are easily identified by the large
white spots covering their grey body. Whale sharks have a large, broad mouth and a flattened
head. They are planktivores.
Figure 6-15 Whale shark (maximum 15 m)
Tiger Shark (Galeocerdo cuvier)
The tiger shark (Figure 6-16) has dark bars and blotches all over its body. They have a large head,
blunt snout and wide mouth. The first dorsal fin on a tiger shark is broad and larger than second
dorsal fin. They can be potentially very dangerous.
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Figure 6-16 Tiger shark (maximum 8 m)
Great Hammerhead Shark (Sphyrna mokarran)
The great hammerhead shark (Figure 6-17) has a very large front dorsal fin. Their head protrudes in
a large hammer shape, with a straight leading edge. The rear edge of their pelvic fin is curved.
Great hammerhead sharks are usually solitary.
Figure 6-17 Great hammerhead shark (maximum 6 m)
Scalloped Hammerhead Shark (Sphyrna lewini)
The scalloped hammerhead shark (Figure 6-18) in contrast to the great hammerhead shark has a
deeply scalloped hammer on the front of its head. The pelvic fin has a straight rear edge. Scalloped
hammerhead sharks have a second dorsal fin smaller than their anal fin.
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Figure 6-18 Scalloped hammerhead shark (maximum 5 m)
Caribbean Stingray (Himantura schmardae)
The Caribbean stingray (Figure 6-19) is the second most commonly sighted stingray in Bacalar
Chico. They often come close to shore feeding on the invertebrates on the seagrass beds. The side
of the head is continuous with the pectoral fins. They can be identified by their entirely circular
shaped disc-like bodies. They also have a whip like tail.
Figure 6-19 Caribbean stingray (maximum 1.2 m)
Southern Stingray (Dasyatis Americana)
The Southern stingray (Figure 6-20) is the most commonly sighted stingray in Bacalar Chico.
Generally sighted in the backreef shallow sites they will often cover their bodies in sand leaving
only their eyes uncovered. They are easily identified from the Caribbean stingray by their pointed
snout and tips of wings. Southern stingrays have a kite shaped body.
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Figure 6-20 Southern stingray (maximum 2 m)
Longnose/Atlantic Stingray (Dasyatis Sabina)
The longnose/Atlantic stingray (Figure 6-21) has a projected, pointed snout and is diamond shaped
with rounded wing tips. They have short anal fins at the base of their tail, and a small body size.
Longnose stingrays are occasionally accidentally caught by fishermen in Corozal Bay Wildlife
Sanctuary.
Figure 6-21 Atlantic stingray (maximum 70 cm)
Spotted Eagle Ray (Aetobatus narinari)
Spotted eagle rays (Figure 6-22) are occasionally
sighted in Bacalar Chico. They can be easily
distinguished from the other ray species by the
numerous white spots and circular marks over their
dark backs. Spotted eagle rays have a pronounced
head, long, thin tail and angular pectoral fins.
Figure 6-22 Spotted eagle ray (maximum 2.5 m)
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