Marine Science Training Handbook
Last updated July 2015
i Blue Ventures Belize Science Training Guide: Invasive Lionfish Monitoring & Research 2013 Expedition
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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Blue Ventures Belize Science Training Guide: Invasive Lionfish Monitoring & Research 2013 Expedition
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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Blue Ventures Belize Science Training Guide: Invasive Lionfish Monitoring & Research 2013 Expedition
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 Figure 1-1 Hawksbill turtle elkhorn corals (Acropora palmata, A. cervicornis).
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, ecosystem- based 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 community- led 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. INTRODUCTION TO CORAL REEFS
3.1. 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 Justification 1. What is the current status of lionfish in • National interest in a population census Belize? • Monitor effectiveness of management effort and market interventions
2. What are the limits to population • Managers of coastal protected areas interest in status and expansion in Belize? potential of invasion in non-reef environments • Long-term downstream impacts on fisheries, food web and ecosystem interactions
3. Is their reproductive cycle governed by • Formation of targeted removal efforts environmental conditions? 4. What does their diet consist of, and • Long-term downstream impacts on fisheries, food web and does it change spatially or temporally? 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 • Long-term downstream impacts on fisheries, food web and with lionfish for common resources? ecosystem interactions • Explore potential biotic resistance of reefs to invasive lionfish
6. Do any native species prey upon • Long-term downstream impacts on fisheries, food web and lionfish, with no negative affect to their ecosystem interactions health? • 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) Figure 5-3 Green morays have been nominated as a predator f. Tiger (M. tigris) 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 Snapper Grouper Beaugregory Schoolmaster Black Grouper Cocoa Damsel Grey Snapper Tiger Grouper Dusky Damsel Mahogany Snapper Goliath Grouper Longfin Damsel Mutton Snapper Yellowmouth Grouper Threespot Damsel Lane Snapper Yellowfin Grouper Cubera Snapper Nassau Grouper Other Damselfish Dog Snapper Red Grouper Bicolour Damsel Yellowtail Snapper Graysby Yellowtail Damsel Coney Blue Chromis Moray Eel Red Hind Brown Chromis Chain Moray Sergeant Major Green Moray Lobster Spotted Moray Caribbean Spiny Lobster Great Barracuda Goldentail Moray Spotted Spiny Lobster
Chapter 6. MEGAFAUNA
6.1. 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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