Marine Science Training Handbook

Last updated July 2015

i Table of Contents CHAPTER 1: THE NATURAL HISTORY OF BELIZE ...... 5 1.1: A brief paleological history ...... 5 1.2:...... 6 Modern Climate ...... 6 1.3:...... 6 Conservation Importance of Belize ...... 6 1.4:...... 6 Bacalar Chico Marine Reserve and National Park (BCMRNP) ...... 6 CHAPTER 2: BLUE VENTURES CONSERVATION AND THE BELIZE PROJECT .. 8 2.1:...... 8 Blue Ventures Conservation ...... 8 2.2: Belize Project ...... 8 2.3: Sarteneja: An Opportunity to Affect the Entire Coastline of Belize ...... 9 Conservation through Collaboration and Partnership ...... 10 The Sarteneja Alliance for Conservation and Development (SACD) ...... 10 Wildtracks ...... 11 Corozal Sustainable Future Initiative (CSFI) ...... 11 The Belize Fisheries Department ...... 11 The Belize Forest Department ...... 11 World Wildlife Fund (WWF) ...... 11 University of Belize ...... 12 Healthy Reefs for Healthy People ...... 12 Southern Environmental Association ...... 12 CHAPTER 3: I ...... 13 NTRODUCTION TO CORAL REEFS ...... 13 Coral Reefs ...... 13 Structure of Corals Reefs ...... 13 Where Reefs Exist ...... 13 Ecosystem Interactions ...... 14 Coral Reefs ...... 14 Seagrass beds ...... 14 Mangroves ...... 14 CHAPTER 4: DISTURBANCES TO CORAL REEFS ...... 16 Storms and Cyclones ...... 16 Coral Bleaching...... 16 Nutrient Enrichment ...... 17 Overfishing and Destructive Fishing Practices ...... 17 Anchor and Diver Damage ...... 17 CHAPTER 5: FISH BIOLOGY AND IDENTIFICATION ...... 18 Class Osteichthyes - Bony Fish ...... 18 Class Chondrichthyes - Cartilaginous fishes ...... 19 Introduction to fish behaviour ...... 20 Diversity ...... 20 Schooling ...... 20 Territoriality ...... 21 Colouration ...... 21 Symbiosis ...... 21 Reproduction, spawning and nesting ...... 21 Sequential hermaphroditism ...... 22 CHAPTER 6: ...... 22 COMMON FISH FAMILY IDENTIFICATION ...... 22 Identifying fish families ...... 22 Scaridae – Parrotfish ...... 23 Labridae – Wrasse ...... 23 Pomacentridae – Damselfish ...... 24 Chaetodontidae – Butterflyfish ...... 24 Pomacanthidae – Angelfish ...... 25 Acanthuridae – Surgeonfish...... 26 Serranidae – Groupers, Hamlets and Soapfish ...... 26 Balistidae – Triggerfish ...... 27 Monocanthidae – Filefish ...... 27 Lutjanidae – Snappers ...... 28 Haemulidae – Grunts ...... 28 Scorpaenidae – Scorpionfish ...... 28 Carangidae – Jacks ...... 29 Sphyraenidae – Barracuda ...... 29 Scombridae – Mackerel ...... 30 Elopidae - Tarpon ...... 30 Gerreidae - Mojarras ...... 31 CHAPTER 7: COMMON MEGAFAUNA IDENTIFICATION ...... 31 Elasmobranchs (sharks and rays) ...... 31 Bull Shark (Carcharhinus leucas) ...... 31 Caribbean Reef Shark (Carcharhinus perezi) ...... 32 Blacktip Shark (Carcharhinus limbatus) ...... 33 Whale Shark (Rhincodon typus) ...... 33 Tiger Shark (Galeocerdo cuvier) ...... 34 Great Hammerhead Shark (Sphyrna mokarran) ...... 34 Scalloped Hammerhead Shark (Sphyrna lewini) ...... 35 Caribbean Round Stingray (Himantura schmardae) ...... 35 Southern Stingray (Dasyatis Americana) ...... 36 Spotted Eagle Ray (Aetobatus narinari) ...... 36 Yellow stingray (Urolophus jamaicensis)...... 37 Lesser Electric Ray (Narcine bancroftii) ...... 37 Turtles ...... 38 Hawksbill Turtle (Eretmochelys imbricata) ...... 39 Green Turtle (Chelonia mydas) ...... 40 Loggerhead Turtle (Caretta caretta) ...... 40 Leatherback Turtle (Dermochelys coriacea) ...... 41 Olive Ridley Turtle (Lepidochelys olivacea) ...... 41 Mammals ...... 42 Bottlenose Dolphin (Tursiops truncates) ...... 42 Atlantic Spotted Dolphin (Stenella frontalis) ...... 42 West Indian Manatee (Trichechus manatus) ...... 43 CHAPTER X: INTRODUCTION TO PLANTAE AND IDENTIFICATION ...... 44 Turf algae ...... 44 Fleshy Macroalgae ...... 45 Dictyota spp...... 45 Lobophora spp...... 45 Crustose coralline algae (CCA) ...... 46 Articulated coralline algae ...... 46 4.4. Seagrass ...... 46 4.5. Cyanobacteria/Blue green algae ...... 47 CHAPTER X: COMMON INVERTEBRATE PHYLA AND IDENTIFICATION ...... 48 Phylum Porifera (Sponges) ...... 48 Phylum Mollusca ...... 50 Gastropoda ...... 50 Flamingo tongue ...... 51 Phylum Echinodermata (Sea Urchins and Sea Cucumbers) ...... 51 Echinoidea (Sea Urchins) ...... 52 Holothuroidea (Sea Cucumbers) ...... 53 Phylum Chordata (Tunicates) ...... 53 Solitary tunicate ...... 54 Colonial/encrusting tunicate ...... 54 Lobsters ...... 55 Caribbean Spiny Lobster (Panulirus argus) ...... 55 Spotted spiny lobster (Panulirus guttatus) ...... 55 Spanish lobster (Scyllarides aequinoctialis) ...... 56 Phylum Cnidaria (Corals, Anemones, Hydroids, and Jellyfish) ...... 56 Scyphozoa (True Jellyfish) ...... 57 Anthozoa (Gorgonians, Corals, Anemones) ...... 58 Hydrozoa (Hydrozoans) ...... 61 Millepora spp. (Fire Coral) ...... 61 CHAPTER X: ORDER SCLERACTINIA: INTRODUCTION AND IDENTIFICATION63 Acroporidae ...... 64 6.2. Poritidae ...... 65 6.3. Siderastreidae ...... 65 6.6. Faviidae ...... 67 6.7. Meandrinidae ...... 68 6.8. Caryophylliidae ...... 68 6.9. Mussidae ...... 69

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 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.

[Type text] [Type text] Page 5 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. 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 is home to a number of species of international concern, including the charismatic Antillean manatee, critically endangered hawksbill turtle (Figure 0-1) and goliath grouper, Yucatan endemics, such as the increasing threatened black cat bird, and critically endangered staghorn and elkhorn corals (Acropora palmata, A. cervicornis).

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Figure 0-1 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.

Figure 0-2 Map of Bacalar Chico National Park and Marine Reserve.

[Type text] [Type text] Page 7 BCMR is also a key part of an international system of connected MPAs (Figure 0-2); 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. 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).

[Type text] [Type text] Page 8  Assist coastal communities in improving marine resource management and conservation efforts.  Provide technical assistance for the effective monitoring and management of MPAs in Belize.  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 0-1). 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 0-1 Map showing the location of Sarteneja (Image from Google Earth, February 2010).

[Type text] [Type text] Page 9 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 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. 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:

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 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.

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.

[Type text] [Type text] Page 11 University of Belize This is the principal university within Belize and has a dedicated department for marine environmental research and tertiary education.

Healthy Reefs for Healthy People The Healthy Reefs for Healthy People Initiative (HRI) is an international, multi-institutional effort that tracks the health of the Mesoamerican Reef, the human choices that shape it and our progress in ensuring its long-term integrity. Launched in 2004, Blue Ventures has been an official partner of HRI since 2012; data collected during expeditions are used in producing the HRI biennial reef health report.

Southern Environmental Association The Southern Environmental Association (SEA), based in Placencia, co-manages Gladden Spit and Silk Cayes Marine Reserve and Laughing Bird Caye National Park. Together, Blue Ventures and SEA are tackling the lionfish invasion coordinating the annual Placencia Lionfish Tournament and monitoring lionfish populations to determine effective management strategies.

[Type text] [Type text] Page 12 CHAPTER 3: 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.

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.

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

[Type text] [Type text] Page 13 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.

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)

Seagrass beds  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.

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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.

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.

[Type text] [Type text] Page 15 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.

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.

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

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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.

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. 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.

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.

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CHAPTER 5: FISH BIOLOGY AND IDENTIFICATION

The superclass Pisces is divided into two classes, the Osteichthyes (the bony fish) and the Chondrichthyes (the cartilaginous fish). Class Osteichthyes - Bony Fish

Figure 1.1 Typical osteichthyes features

The bony fish (Figure 1.1) comprise the largest class of the vertebrates, with over 20,000 species worldwide, of which 7,000 are coral reef fish species. The bony fish have calcified skeletons, making their bones much harder than the cartilage skeleton of the Chondrichthyes. The bony fish have great manoeuvrability and speed, as well as highly specialised mouths equipped with protrusible jaws. Most bony fish have a swim bladder, a gas-filled internal pocket that can be inflated and deflated at will, in order to maintain neutral buoyancy and to stay upright. The majority of fish propel themselves by sweeping their caudal (tail) fin from side to side, whilst the dorsal fin maintains the vertical axis of the fish and prevents rolling. Fish have a well-developed sense of smell and some species possess barbels (Figure 1.2), which are covered in taste receptors and used to locate food.

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Figure 1.2 Barbels (circled in red) on a spotted goatfish, Pseudupeneus maculatus

Fish respire by passing water over their gills, through which they absorb dissolved oxygen, and are able to move an estimated 74% of the dissolved oxygen from the water. Their skin is covered in mucus glands and is protected by dermal scales. A hard bony plate known as the operculum protects the gills, a feature absent in the elasmobranchs (Chondrichthyes). Osteichthyes also possess a line of small perforated tubes, called the lateral line, that run just under the skin along the midlateral part of the body, and are often visible. These tubes detect minute vibrations in the water, allowing fish to sense the movement and motion of other animals in the water. Class Chondrichthyes - Cartilaginous fishes

Figure 1.3 Typical cartilaginous fish features (shark species)

The Chondrichthyes (sharks and rays) (Figure 1.3) have skeletons that are composed of cartilage. Unlike the bony fish they have no internal swim bladder to keep buoyant, but instead have a greatly enlarged oily liver running the length of their body. Oil is lighter than water and serves to make the animal more buoyant. Sharks must continually swim to remain elevated in the water column and their fins provide hydro-dynamic lift in a similar fashion to the wings of an aeroplane. Males are distinguished from females by two long finger-like fins behind their pelvic fins, known as claspers, which are used for mating. The skin of the Chondrichthyes is not

[Type text] [Type text] Page 19 covered in scales but is either smooth or covered in many microscopic teeth known as dermal denticles, which serve to break the water tension as they swim through the water. Sharks have a highly developed sense of smell and this allows them to detect minute traces of scent in the open ocean to locate food. Sharks sight varies from species to species although all have excellent low light vision because of a light reflective membrane on the retina. This results in light being reflected back through the eye allowing them to see very well at dusk and night time when these animals normally hunt. Sharks and rays have electro-receptors that are sensitive to the magnetic fields produced by other living animals and allow sharks to close a membrane over their eye for protection in the last few moments before they strike. These finely tuned senses allow sharks to be very effective predators in murky and low levels of light. Reproduction in the Chondrichthyes can take one of three forms. Once the eggs are fertilised they develop either encased in a hard envelope outside the parent’s body (ovoviviparity) or encased eggs develop within the parent’s body (oviparity), or finally eggs develop attached to a placenta-like structure within the parent and are born live (viviparity). Introduction to fish behaviour

Diversity The variety of niches provided by coral reefs, mangroves and seagrass beds enable a diverse range of fish to inhabit these ecosystems. The availability of resources supports corallivores (e.g. butterflyfish species), herbivores (eg. surgeonfish species), planktivores (e.g. whale sharks) and invertivores (e.g. the southern stingray). Additionally, the architectural complexity of the reef structure provides a habitat suitable for ambush predators such as the moray eels and groupers. Fish behaviour can be the first key to accurate identification of fish families and species. For example, damselfish species, such as the bicolour damsel and yellowtail damsel, are herbivores, and as such will be closely associated with the reef substrate. However, blue chromis, also from the damselfish family, are planktivores and therefore swim slightly above the reef in the water column itself.

Schooling Schooling is another behaviour that is commonly exhibited by only certain species. Visually similar fish species can be positively identified by their tendency to school. For example, the blue chromis and creole wrasse share a similar colouration, shape and size; but creole wrasse often form large schools, whereas blue chromis will only aggregate in small groups. The reasons for schooling can range from cooperative hunting, to mating and overwhelming territories. Schooling behaviour can be classified in three categories: polarised schools, aggregations and non-polarised schools. Polarised schools occur when the fish act as a single unit, for example Creole wrasse. Aggregations occur when multiple species are attracted to the same resource, for example, French grunts, bluestriped grunts and white grunts. Non-polarised schools occur when the same fish species aggregate close together.

[Type text] [Type text] Page 20 Territoriality Fish species are usually more aggressive to other individuals of the same species or similar species competing for same resources. This occurs because species that share similar niches have similar needs, and territorial behaviour may change depending on the abundance of resources. Territory sizes vary from species to species, and the size or location of the territory may change depending on time of day. Triggerfish species have a conical shaped territory. Certain fish exhibit territorial behaviour, such as damselfish which ’farm’ algae. In this case, a seemingly inquisitive fish may actually be defending its territory against a diver. Nesting fish may also display territoriality, and when male Sergeant Major damselfish guard their nest their colouration can become more strongly blue.

Colouration Many fish species utilise colouration as a means of crypsis or mimicry. Ambush predators, such as groupers, are camouflaged. The markings on a Nassau grouper serve to break up the outline of the fish, concealing it from its prey; whilst scorpionfish mimic dead coral and rocks as a disguise. Pelagic species such as jacks are silvery in colouration as this serves the best camouflage against the backdrop of the open ocean.

Symbiosis Symbiotic relationships are commonly found throughout the reef between many fish species, and also between fish species and other groups of organisms, such as the crustaceans. Symbiosis can be one of three forms; commensalism, mutualism or parasitism. Commensalism occurs when the one species gains from the relationship and the other species is not affected either negatively or positively. For example, remoras have a specially adapted plate on their head allowing them to attach to much larger fish species, from which it gains a free ride, protection and food scraps. The host remains unaffected. Mutualism occurs when both species gain from the relationship. For example, cleaner gobies will feed on parasites located on larger fish. In this case, both parties benefit as the cleaner receives a free meal and the host fish benefits from improved health. Parasitism occurs when the host species is negatively affected by the parasitic species. For example, parasitic isopods attach to the operculum of fish and feed on their blood.

Reproduction, spawning and nesting The majority of fish species release eggs that are fertilised externally. Many species are broadcast spawners where the eggs are released into the open sea, where fertilisation will occur, and are not cared for subsequently. Some species lay their eggs in nests and will guard them until they hatch, such as many damselfish species. Fertilised eggs hatch into larvae and go through several stages of development until they become juveniles. Juvenile fish often have distinct colouration and patterns from their parents.

[Type text] [Type text] Page 21 Sequential hermaphroditism Many fish species are able to change sex during their lifetime, and are known as sequential hermaphrodites. Wrasse and parrotfish species exhibit sequential hermaphroditism (Figure 1.4). This occurs when the largest initial phase female of the group changes sex, into a terminal phase male. Species that change from female to male are known as protogynous hermaphrodites. Terminal males are always dominant over initial phase adults, both males and females. The presence of a terminal male will inhibit the changing of any other initial females in the group. Initial phase males are unable to change into terminal males. Initial phases tend to display dull colouration and patterning, whilst terminal phases are often markedly different with vivid colouration.

JUVENILE PHASE (MALE/FEMALE) INITIAL PHASE (FEMALE) TERMINAL PHASE (MALE)

INITIAL PHASE (MALE)

Figure 1.4 Sequential hermaphroditism shown by the stoplight parrotfish

CHAPTER 6: COMMON FISH FAMILY IDENTIFICATION Identifying fish families

When confronted with the large numbers of fish on a coral reef it is easy to feel overwhelmed with trying to identify families, let alone individual species. It is important to not rely too heavily on the colour of fish when trying to identify fish families but instead to observe their size, body shape and behaviour closely. The colour of fish is only really useful in identifying individual species within a family and even then it can be difficult as species colour can be different for each sex or can change as they age. Some fish species also mimic the colour of other species making it even more important that anyone trying to identify fish is familiar with the body shape of each fish family.

[Type text] [Type text] Page 22 Scaridae – Parrotfish The parrotfish (Figure 2.1) closely resemble wrasse but have teeth fused into beak-like plates, which is not only the origin of their name but also the defining characteristic of the family. They are some of the most important reef herbivores in the Caribbean, as their diet primarily consists of algae, although they do also feed on coral. Parrotfish crush algae-encrusted rock and live coral with their beak-like teeth before digesting it. This causes parrotfish to excrete plumes of sand, a second distinguishing characteristic of the family, and makes them the biggest producers of sand on coral reefs. Similar to the wrasse family, the parrotfish also swim in a flapping motion using their pectoral fins. Individual parrotfish species can also be difficult to identify because they also change colour with age and sex. During the day parrotfish are seen swimming alone or small schools around the reef, biting chunks of rock or coral with their teeth and excreting puffs of sand. At night parrotfish sleep wedged in holes and crevices on the reef; some species can surround themselves with a mucus cocoon that may help to protect them from predators by hiding their scent.

Figure 2.1 Queen parrotfish, Scarus vetula (20 – 50 cm) Labridae – Wrasse Wrasse (Figure 2.2) are among the most diverse group of fishes in both size and body shape, which also makes them one of the hardest families to identify species correctly. Typically wrasse have elongate bodies, terminal mouths (usually with thickened lips), and one or more pairs of protruding canine teeth. Wrasse have a distinct swimming pattern, which they share with the parrotfish family, using primarily their pectoral fins in a flapping motion. Wrasses also generally have a single, unnotched dorsal fin. Individual wrasse species can be particularly difficult to identify because most species have complex and brilliant colour patterns that change with growth or sex. Most wrasse are carnivores of benthic invertebrates or fishes although some are planktivores, corallivores, or feed on ectoparasites on other fishes (cleaner wrasse). Wrasse are normally seen swimming rapidly around the reef alone or in small groups.

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Figure 2.2 Spanish hogfish, Bodianus rufus (8 – 50 cm) Pomacentridae – Damselfish Damselfish are a large family with over 100 species and are some of the most commonly seen reef fish. They are small, and generally no larger than 15 cm. They have moderately deep compressed bodies, continuous dorsal fins, and small terminal mouths. Some damselfish species are highly territorial and will confront divers underwater. Many species are often seen in medium sized shoals living closely associated with a coral head which they retreat into if approached. All lay demersal eggs that are defended by males.

Figure 2.3 Yellowtail damselfish, Microspathodon chrysurus (3 - 15 cm) Chaetodontidae – Butterflyfish The butterflyfish are among the most colourful and conspicuous reef fish. They have highly compressed, disk-like bodies covered with small scales, a small protractible mouth with small brush-like teeth, and a long continuous dorsal fin. They are typically diurnal and have minimal home-ranges. Most species of butterflyfish live closely associated with coral and feed on coral polyps. Butterflyfish also feed on small invertebrates, fish eggs and filamentous algae. Butterflyfish tend to be gonochoristic1 with most species mating in pairs for years, if not for life, and are therefore often seen in pairs on the reef. Many species of butterflyfish have a dark stripe that camouflages their eyes, and juveniles are often a different colour and pattern to adults. Butterflyfish tend to be timid and are likely to swim away from divers.

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Figure 2.4 Foureye butterflyfish, Chaetodon capistratus (10 - 20 cm) 1Pomacanthidae – Angelfish Angelfish (Figure 2.5) have a compressed body with a small mouth. The key identification feature of the angelfish family is that they all possess a spine that extends backwards from the front of their operculum (gill plate). Juveniles and adults often have strikingly different colour patterns. They are active by day and generally seek shelter in caves and crevices at night. Most species feed on sponges, some soft bodied invertebrates, algae and fish eggs, whilst other species feed on small invertebrates and filamentous algae. Angelfish tend to be quite shy and many species will retreat into crevices and under coral when approached by a diver. Angelfish are usually observed as individuals or pairs.

Figure 2.5 French angelfish, Pomacanthus paru (10 – 40 cm)

1 Those species with sexes separate, the male and female reproductive organs being in different individuals.

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Acanthuridae – Surgeonfish Surgeonfish (Figure 2.6) have ovate or elongate compressed bodies, small terminal mouths and a continuous dorsal and anal fin. The distinguishing feature of this family, and the origin of their common name, is the sharp blades which sit on each side of the caudal peduncle (the area between the body and the tail). These blades act as a defence against predation. Surgeonfish are some of the most important reef herbivores in the Caribbean as they graze on all types of algae. Their gizzard like stomach uses sand to grind the algae to aid digestion.

Figure 2.6 Ocean surgeonfish, Acanthurus bahianus (10 - 25 cm)

Serranidae – Groupers, Hamlets and Soapfish Groupers (Figure 2.7), hamlets and soapfish are a large and diverse family of reef fish. The family all share a distinctively shaped pupil. Groupers are large, robust-bodied bottom dwellers with large, down-turned mouths that they use to suck in prey. Groupers are normally seen as solitary individuals and are voracious predators of crustaceans, fishes, and cephalopods. Some species of grouper hide from divers and the most seen of an individual is its tail disappearing under a rock, whilst others rest on coral heads and rock. Groupers also like to rest in caves and holes. Large species may live for several decades and reach weights of up to 400 kg and 3 m in length. Many species are sequential hermaphrodites (first female then male) and if larger fish are harvested the population could contain a disproportionate number of smaller females.

[Type text] [Type text] Page 26 Figure 2.7 Black grouper, Mycteroperca bonaci (50 – 150 cm) Balistidae – Triggerfish Triggerfish (Figure 2.8) are characterised by a first dorsal fin with three spines that can lock upright and a swimming motion that involves undulating the second dorsal fin and anal fin simultaneously. They have a relatively deep, compressed body with eyes set high on the head, a small terminal mouth and large snout with sharp teeth. Triggerfish are carnivores of urchins and other echinoderms, corals, fish, molluscs and crustaceans. Most species lay demersal eggs which are often viciously guarded by at least one of the parents and they will protect a cone shaped area that radiates upwards from their eggs. Most species of triggerfish are seen solitary, often in sandy patches, but some are found in large schools such as the black durgon (Melichthys niger).

Figure 2.8 Black durgon, Melichthys niger (20 – 40 cm) Monocanthidae – Filefish Filefish (Figure 2.9) are very similar to triggerfish but have only one long, prominent dorsal spine compared to the three shorter dorsal spines on the triggerfish. Filefish also have more compressed, thinner bodies. Filefish lack large obvious scales. They are normally seen solitary or in pairs swimming close to the reef.

Figure 2.9 Whitespotted filefish, antherhines macrocerus (10 – 40 cm)

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Lutjanidae – Snappers Snappers (Figure 2.10) are medium to large robust fish that are commonly seen in schools swimming off the reef. They have continuous dorsal fins and large coarse scales. All but one species of snapper in the Caribbean has a square-shaped tail, with only one species possessing a forked tail. Most species are predators of crustaceans and smaller fish. Many smaller species school by day, and disperse to feed on benthic invertebrates at night, whilst some larger species tend to be solitary.

Figure 2.10 Grey Snapper, Lutjanus griseus (35 - 45 cm) Haemulidae – Grunts Grunts (Figure 2.11) are most easily confused with snappers. Most grunts have a steeply sloping forehead and some have thickened lips. Unlike snappers, all grunts have a shallowly forked tail. Grunts are normally seen in small groups or solitary, swimming slowly near the reef, however, in the backreef large multispecific aggregations can form. Grunts generally feed at night on benthic invertebrates and small fish.

Figure 2.11 Bluestriped grunt, Haemulon sciurus (15 - 25 cm)

Scorpaenidae – Scorpionfish Scorpionfish and lionfish both have venomous fin spines. Scorpionfish are well-camouflaged fish that are covered in appendages and tassels, and remain motionless resting on coral heads, rocks or the substrate waiting for prey. Scorpionfish will dart away from their resting place if a diver approaches too close and are often not observed until this point. Some have brightly

[Type text] [Type text] Page 28 coloured undersides or parts of their pectoral fins, which may be flashed as a warning to potential predators. Lionfish have long spines on their dorsal and pectoral fins (Figure 2.18). They have a large spiny head and a bony ridge on their gill plate. Lionfish spread their pectoral fins out like a net to trap prey. They have venomous spines on their pelvic, dorsal and anal fins. Lionfish are an invasive species in the Caribbean, introduced from the Pacific into the Atlantic in 1983. They were first recorded in Belize in 2008 and have since become well established throughout the country. They are voracious predators consuming juvenile fish and shrimp species.

Figure 2.18 Lionfish, Pterois volitans Carangidae – Jacks

Jacks (Figure 2.20) are medium to large silvery fish. They are fast-swimming pelagic fish so are generally observed swimming in the deeper water off the reef. They have two dorsal fins, a long pectoral fin and a highly forked tail fin. They are often seen in schools and are an economically important food fish.

Figure 2.20 Bar jack, Carangoides ruber (30 – 100 cm) Sphyraenidae – Barracuda

[Type text] [Type text] Page 29 Barracudas (Figure 2.21) are elongate fish with silvery bodies. They have long, pointed heads with large down-turned mouths with numerous sharp teeth. Barracudas also have two widely spaced dorsal fins. They are often seen solitary but more often they are seen in schools. They very rarely attack divers but it is reported that they may sometimes be attracted to shiny, silvery objects in the water.

Figure 2.21 Great barracuda, Sphyraena barracuda (70 -100 cm)

Scombridae – Mackerel

Mackerels (Figure 2.22) are elongated, silver, fast swimming predators of the open sea that only occasionally pass over reefs. They have two dorsal fins that fold into grooves. Between their dorsal fin and tail and their anal fin and tail they have small finlets, to increase maneuverability and balance. They have a strong, forked tail signifying the speed at which they pass through the water. Tunas and ceros are members of this family.

Figure 2.22 Cero, Scomberomorus regalis (50 – 90 cm) Elopidae - Tarpon Tarpon (Figure 2.23) are a commercially important fish family. They have a flexible and acrobatic body enabling them to work their way off of a fish-hook, which makes them appealing to sport fishermen, although in Belize they are strictly catch and release. Tarpon can live in hypoxic2 water as they possess a modified lung-like swim bladder. They use their upturned mouths to gulp air at the surface. Tarpon can be very long-lived and grow to a very large size. They commonly inhabit the shallow area of mangrove habitats.2

22 2 An aquatic system with a low concentration of oxygen (1 – 30% saturation). A healthy aquatic system is normally 80% oxygen saturation.

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Figure 2.23 Tarpon, Megalops atlanticus (60 – 120) Gerreidae - Mojarras Mojarras (Figure 2.25) are normally found in seagrass beds and mangroves and are the most popular fish to eat in Sarteneja. Mojarras have bright, reflective, obvious scales. They have a laterally compressed body, with highly protrusible mouths and deeply forked tail. Rarely on reefs, they inhabit shallow surge-swept sandy shorelines, rubble, grass or mud flats where they feed on small invertebrates. Several species are difficult to distinguish, but careful attention to subtle markings and body shapes usually provides a correct identification.

Figure2.25Yellowfinmojarra,Gerrescinereus (20–40cm)

CHAPTER 7: COMMON MEGAFAUNA IDENTIFICATION Elasmobranchs (sharks and rays)

Bull Shark (Carcharhinus leucas)

[Type text] [Type text] Page 31 The bull shark (Figure 3.1) 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 3.1 Bull shark, Carcharhinus leucas (maximum 4 m)

Caribbean Reef Shark (Carcharhinus perezi) The Caribbean reef shark has a grey upper half of its body, with a fading white underside. They have rounded snout and a dusky tip on their anal fin, with a sharply pointed first dorsal fin and long, narrow pectoral fins.

Figure 3.2 Caribbean reef shark, Carcharhinus perezi (maximum 3.5 m)

Nurse Shark (Ginglymostoma cirratum) The nurse shark (Figure 3.3) is the most commonly seen shark in the Bacalar Chico Marine Reserve. Often seen ‘resting’ 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.

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Figure 3.3 Nurse shark, Ginglymostoma cirratum (maximum 4.5 m)

Blacktip Shark (Carcharhinus limbatus)

The blacktip shark (Figure 3.4) is distinguished by black edging on its pectoral, pelvic, dorsal and lower lobe of the caudal fin, though this fades to become more 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.

Figure 3.4 Blacktip shark, Carcharhinus limbatus (maximum 3 m)

Whale Shark (Rhincodon typus)

The whale shark (Figure 3.5) 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; and are planktivores.

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Figure 3.5 Whale shark, Rhincodon typus (maximum 15 m)

Tiger Shark (Galeocerdo cuvier)

The tiger shark (Figure 3.6) has dark bars and blotches all over its body, resembling stripes. 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.

Figure 3.6 Tiger shark, Galeocerdo cuvier (maximum 8 m)

Great Hammerhead Shark (Sphyrna mokarran)

The great hammerhead shark (Figure 3.7) 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.

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Figure 3.7 Great hammerhead shark, Sphyrna mokarran (maximum 6m)

Scalloped Hammerhead Shark (Sphyrna lewini) The scalloped hammerhead shark (Figure 3.8) 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.

Figure 3.8 Scalloped hammerhead shark, Sphyrna lewini (maximum 5 m)

Caribbean Round Stingray (Himantura schmardae)

The Caribbean round stingray (Figure 3.9) is the second most commonly sighted stingray in Bacalar Chico Marine Reserve. They often come close to shore feeding on the invertebrates on

[Type text] [Type text] Page 35 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 3.9 Caribbean stingray, Himantura schmardae (maximum 1.2 m)

Southern Stingray (Dasyatis Americana) The Southern stingray (Figure 3.10) is the most commonly sighted stingray in Bacalar Chico Marine Reserve. They are generally sighted in shallow backreef areas where they will often cover their bodies in sand leaving only their eyes uncovered. They are easily identified from the Caribbean round stingray by their pointed snout and tips of wings. Southern stingrays have a kite shaped body.

Figure 3.10 Southern stingray, Dasyatis Americana (maximum 2 m)

Spotted Eagle Ray (Aetobatus narinari)

Spotted eagle rays (Figure 3.12) are occasionally sighted in Bacalar Chico Marine Reserve. They can be easily distinguished from the other ray species by the numerous white spots and circular

[Type text] [Type text] Page 36 marks over their dark backs. Spotted eagle rays have a pronounced head, a long, thin tail and angular pectoral fins.

Figure 3.12 Spotted eagle ray, Aetobatus narinari (maximum 2.5 m)

Yellow stingray (Urolophus jamaicensis)

Yellow stingray have numerous pale spots and blotches on yellowish brown coloured body (Figure 3.13). The snout and tips of pectoral fins rounded and the tail is stout with venomous spines near the end. Its maximum diameter is 35cm.

Figure 3.13 Yellow stingray Urolophus jamaicensis (maximum 35cm)

Lesser Electric Ray (Narcine bancroftii)

[Type text] [Type text] Page 37 The lesser electric ray is grey to brown colour and may have dark blotches and/or spots (Figure 3.14). These nearly circular rays have a short tail with thick base. The tail has two dorsal fins of equal size. Maximum diameter is 45cm.

Figure 3.14 Lesser electric ray Narcine bancroftii (maximum 45cm)

Turtles

All species of marine turtle 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 3.14). 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 shell’s edge). The size of the tail on a turtle can be used to identify its sex once mature. 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.

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Figure 3.14 Turtle identification guide

Hawksbill Turtle (Eretmochelys imbricata)

The hawksbill turtle (Figure 3.14) has an overhanging upper beak (hence the name hawksbill), though this should not be used as the sole feature for identification. The hawksbill is one of the most commonly sighted turtles in Bacalar Chico Marine Reserve, seen both on the forereef and backreef. They can be accurately distinguished from the green turtle by the two pairs of scales between their eyes. They often have brown shells, with yellow-brown-like markings. The rear border plates on a hawsksbill turtle have a serrated edge, and the shell plates overlap.

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Figure 3.14 Hawksbill turtle, Eretmochelys imbricata (maximum 1.2 m).

Green Turtle (Chelonia mydas)

Green turtles (Figure 3.15) often have brown shells with olive shadings, 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 second most commonly sighted turtles in Bacalar Chico.

Figure 3.15 Green turtle, Chelonia mydas (maximum 1.5 m)

Loggerhead Turtle (Caretta caretta) Loggerhead turtles (Figure 3.16) are the second largest marine turtle. Sighted rarely in Bacalar Chico Marine Reserve they have a large blunt head and powerful jaws, which easily distinguishes them from the other turtle species found in this part of Belize. Loggerheads have a steeply domed carapace with a reddish, brown shell.

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Figure 3.16 Loggerhead turtle, Caretta caretta (maximum 2 m)

Leatherback Turtle (Dermochelys coriacea)

Leatherback turtles (Figure 3.17) are the largest marine turtle. They possess no shell plates; instead their back is covered by a tough leather-like skin, allowing them to dive to great depths. They are also the only marine turtle to thermoregulate, enabling them to inhabit all of the world’s oceans.

Figure 3.17 Leatherback turtle, Dermochelys coriacea (maximum 1.8 m)

Olive Ridley Turtle (Lepidochelys olivacea)

The olive ridley turtle (Figure 3.18) are listed as vulnerable by the IUCN, and are very rare in Bacalar Chico. They are olive (dull) in colour and are found in tropical open waters.

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Figure 3.18 Olive Ridley Turtle Lepidochelys olivacea

Mammals

Bottlenose Dolphin (Tursiops truncates) Bottlenose dolphins (Figure 3.18) are a light blue to slate grey colour, with a paler underside. They are the most commonly sighted dolphin in Bacalar Chico. They have a pronounced beak and a rounded forehead. Bottlenose dolphins can be identified from the Atlantic spotted dolphin by their slightly hooked, tall dorsal fin. They are normally found in small groups.

Figure 3.18 Bottlenose dolphin, Tursiops truncates (maximum 3m)

Atlantic Spotted Dolphin (Stenella frontalis)

The Atlantic spotted dolphin (Figure 3.19) is smaller in size than the bottlenose dolphins. They are a grey to black in colour with pale spots. Atlantic spotted dolphins are nearly always seen in large groups.

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Figure 3.19 Atlantic spotted dolphin, Stenella frontalis (maximum 2.5 m)

West Indian Manatee (Trichechus manatus)

The West Indian manatee (Figure 3.20) is the largest species of manatee. 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. They have grey skin colour and a large head with mobile lips covered in bristles. Manatees are easily spotted by their large paddle shaped tails, which make a circular ripple on the surface of the water.

[Type text] [Type text] Page 43 Figure 3.20 West Indian manatee, Trichechus manatus (maximum 3.5 m)

CHAPTER X: INTRODUCTION TO PLANTAE AND IDENTIFICATION

Algal species are very important for reef health. Algae and coral compete for space in reef habitats, and fast-growing algae will outcompete coral if grazing of algae is not high enough or eutrophication enhances algal growth rates. This can lead to an algal phase-shift3. Calcareous forms of green algae (in particular Halimeda spp.) contribute significant amounts of calcium carbonate to marine sediments found in seagrass beds, and on coral reefs and beaches. Calcareous red algae (crustose and articulated coralline algae) play an important role in the reef building process by adding calcium carbonate to the reef and aiding in cementation. Most herbivore groups are able to feed on turf algae, while fewer feed on macroalgae and even fewer on coralline algae. When herbivory is reduced or removed, turf algae are able to colonise on and around coralline algae and once established they begin to trap sediment and kill underlying coralline algae. When grazing intensity increases, turf and macroalgal cover should decrease.

Turf algae Turf algae (Figure 4.1) are formed from tiny filaments, with canopy heights of less than 1 cm. They are often able to recover rapidly after being partially consumed by herbivores. Surgeonfish, damselfish and parrotfish feed on turf algae. Turf algae are capable of trapping ambient sediment and may outcompete corals for space if herbivory rates are low. They are easily identified as a moss- like covering over rocks and sand.

Figure 4.1 Turf algae

[Type text] [Type text] Page 44 Fleshy Macroalgae Fleshy macroalgae (Figure 4.2), unlike turf algae, has a clear growth form. The blades of macroalgae are larger than turf algae, with a canopy height usually greater than 1 cm.

Figure 4.2 Fleshy macroalgae

Dictyota spp. Dictyota spp. (Figure 4.3) are branched algae which fork near their rounded or pointed ends. It forms mats of dense, loose-packed, flat leaves that overgrow the substrate. Torn algae can be misidentified as Dictyota so it is important to look at the structure as a whole.

Figure 4.3 Dictyota spp. (4 – 18cm)

Lobophora spp. Lobophora spp. (Figure 4.4) are an encrusting fan leaf algae. The thin fan-shaped leaves are often overlapping. Lobophora spp. only ever grow flat to the substrate and are found at depths of 4 m – 100 m. They can be commonly misidentified with a species of macroalgae, which forms lobe-like, upright leaves.

[Type text] [Type text] Page 45 Crustose coralline algae (CCA) Crustose coralline algae (Figure 4.6) play two important roles in the coral reef community, firstly, by contributing calcium carbonate to reef structure, and secondly, by facilitating the settlement of coral recruits. This occurs when the CCA provides a clean substrate for the coral to then grow over. Looking like paint splashed over the rock substrate, CCA is found in shades of pink, purple, red and orange. It is also able to form brittle plates, growing actively away from the substrate upon which it initially encrusted.

Figure 4.6 Crustose coralline algae (CCA)

Articulated coralline algae Articulated coralline algae (Figure 4.6) are branching calcareous red algae. It is easily identified by its twig-like structure, and is frequently seen growing in bunches off the substrate and within crevices formed by submassive and foliose corals.

Figure 4.7 Articulated coralline algae

4.4. Seagrass

[Type text] [Type text] Page 46 Seagrass is an angiosperm (a true flowering plant) and has leaves not blades (Figure 4.8). Instead of a holdfast and stipe as seen in the algae species, seagrass has an underground root system. Within the leaves there are visible veins running up the leaves. Seagrass beds are a very important habitat for invertebrates, fish and bird species (Figure 4.9). It is also the sole food source for manatees and forms the primary part of an adult green turtle’s diet. It also provides protection against coastal erosion.

Figure 4.8 The differing features of seagrass and algal species

Figure 4.9 Seagrass

4.5. Cyanobacteria/Blue green algae Cyanobacteria/blue green algae (Figure 4.10) are commonly known as ‘troll’s hair’. The thin filaments resemble a coarse hair-like clump or mat on the substrate. Most commonly found in shades of reddish brown, it is also seen in a blue-green form. Cyanobacteria can form rapidly expanding dense mats, threatening nearby corals by shading and overgrowth

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Figure 4.10 Blue green algae/Cyanobacteria

CHAPTER X: COMMON INVERTEBRATE PHYLA AND IDENTIFICATION Invertebrates account for 95% of species in the Animal Kingdom. The Animal Kingdom has just over a million scientifically described species categorised into thirty-two phyla. The phylum Chordata, which includes all fish, birds, and mammals, only contains around 45,000 (3%) species, of which only 4,000 (0.03%) are mammals. The remaining phyla are comprised of invertebrate groups. Some invertebrates are "keystone species" playing particularly important roles in the maintenance of biotic communities. Coral reefs are perhaps the most dramatic example, providing a wide range of niches for a diversity of plants and perhaps one-third of all fish species. Here we will take a brief look at some of the most commonly seen reef invertebrates.

Phylum Porifera (Sponges) Sponges are the oldest living group of metazoan (multi-cellular organisms) with over 9000 described species to date. They first appear in the fossil record over 600 million years ago during the Late Precambrian period. Sponges have simple body plans that function at the cellular level. They have neitherorgansnoradigestivecavityormouthandlackbothmusclesandnerves. Spongesaresessile filter feeders and they have tiny inhalant pores, called ostia, in their outer walls through which water is drawn (Figure 5.1). Cells in the sponge walls, called choanocytes, filter bacteria and food particles from the water. Water flowing through sponges therefore provides food and oxygen and acts as a means for waste removal. These cells also have whip-like flagellum which drives the flow of water into the sponge. The flow of water through the sponge is unidirectional and is pumped out of the body through exhalent holes. The volume of water passing through a sponge can be enormous, up to 20,000 times its volume in a single 24 hour period.

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Figure 5.1 The ostia (inhalant pores) of a sponge, through which water is filtered, are clearly visible

Sponges can trap roughly 90% of all bacteria in the water they filter. Some sponges also harbour symbionts such as green algae, dinoflagellates, or cyanobacteria, from which they also derive nutrients. Sponges can reproduce asexually and sexually. Most sponges that reproduce by sexual means are hermaphroditic and produce eggs and sperm at different times. Sperm are frequently "broadcast" into the water column and are subsequently captured by female sponges of the same species. Once the larvae are in the water column they settle and develop into juvenile sponges. Asexual reproduction is through budding or fragmentation. Sponges on the reef provide homes for a large diversity of other organisms, including shrimps, crabs, barnacles, worms, brittlestars, sea cucumbers, other sponges, cyanobacteria, and light- loving microbes. Sponges appear to suffer little predation, only being fed on by nudibranchs and certain species of fish and turtle. This is thought to be due to the complex protective compounds produced by sponges as a by-product of their daily metabolism. Several of these sponge compounds are shown to be active against certain tumour cell types and highlights the possible medicinal resource of the Porifera. Sponges can develop into diverse life forms, ranging from large barrels (Figure 5.2), to encrusting sheets (Figure 5.3). The encrusting sheets can be extremely thin often resulting in a clear view of the dead coral beneath, meaning that care should be taken when identifying. Their structure is supported by a skeleton composed of an organic substance called spongin, or they may have calcareous or siliceous skeletons composed of chambers, or more commonly rod-like branched elements called spicules.

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Figure 5.2 Erect sponge

Figure 5.3 Encrusting sponge

Phylum Mollusca The molluscs are a diverse group of over 160,000 different species, of which about half are marine. The phylum Mollusca is divided into eight classes but there are three major classes, the gastropods, which comprise 80% of all living molluscs, the bivalves and the cephalopods. Although the members of this phylum range in body shape from the gastropod snails to the giant squid there several key features which define the molluscs. The body is soft, unsegmented and bilaterally symmetrical usually with a definite head. The ventral or lower part of the body wall is often specialised into a muscular foot and used chiefly for locomotion. The dorsal body wall is typically surrounded by a thin mantle, which encloses the mantle cavity in which the gills are found, and secretes the shell material in shelled molluscs. Gastropoda Gastropod literally means ‘stomach-foot’ and they are the most successful and most commonly seen class of molluscs. Gastropods have a single, often coiled, shell within which the body is protected. All gastropods have a toothed radula – a chitinous band in the mouth covered in horny teeth used to scrape and rasp food. The majority of gastropods feed on algae, sponges, other molluscs and small invertebrates. This class includes conchs (Figure 5.4), cowries, helmet

[Type text] [Type text] Page 50 shells, whelks, olive and cones shells. It is important to note that the mantle can extend over the entire shell in some species making gastropods harder to identify.

Figure 5.4 Queen conch Flamingo tongue

The flamingo tongue (Figure 5.5) is a type of cowrie. They live on gorgonians feeding on the polyps. The Caribbean spiny Lobster is a major predator of flamingo tongues. Overexploitation of lobsters has been linked to increases in flamingo tongue populations. As flamingo tongues are more conspicuous than lobsters, they are monitored as a potential indicator species for lobster population status.

Figure 5.5 Flamingo tongue Phylum Echinodermata (Sea Urchins and Sea Cucumbers) The Echinoderms constitute around 7000 described living species with another 13,000 known from fossil records dating back 600 million years ago. The name echinoderm literally means ‘spiny-skinned’ and refers to their endoskeleton of calcium carbonate plates usually baring spines, which characterises this phylum. Also characterising this phylum is five-part radial symmetry and an internal water vascular system. This water vascular system is composed of an intake sieve plate in which water is drawn into a series of canals which radiate through the body and end in tube feet. Echinoderms have no excretory organs but usually a complete gut

[Type text] [Type text] Page 51 (mouth, stomach, intestines and anus) in one. The families are exclusively marine and the majority of species have separate sexes. The echinoderms are also renowned for their ability to regenerate lost body parts. Echinoidea (Sea Urchins) Sea Urchins (Figure 5.6) are commonly seen on the reefs and are normally round-bodied with stiff and often sharp spines. Most species are nocturnal and are seen in caves and crevices during the day. They are major grazers on the reef helping to turnover reef sediments and helping to release valuable nutrients. Sea urchins graze on algae and other organisms found on the substrate such as sponges and bryozoans.

Figure 5.6 Sea urchin

The species Diadema antillarum, commonly known as the long-spined sea urchin (Figure 5.7), is monitored in Bacalar Chico Marine Reserve. Once forming dense aggregations in areas with an abundance of algae, Diadema populations were almost wiped out in the 1980s throughout the Caribbean due to a disease outbreak. The juvenile Diadema has black and white banded spines, whilst the adult has plain black or white spines.

Figure 5.7 Diadema/Long-spined sea urchin, Diadema antillarum

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Holothuroidea (Sea Cucumbers) Sea cucumbers (Figure 5.8) are elongate animals with a mouth surrounded by short tentacles at the anterior end of the body. They are normally seen lying on the sand floor where they feed by ingesting large amounts of sand and digesting the organic material. Sea cucumbers often leave a trail of sand as they feed as sand is excreted from the anus. The majority of sea cucumbers are large, solid, cylindrical-shaped animals, with some species having long, branching tentacles surrounding their mouths. As a defense mechanism some species are able to eject cuvierian tubules (sticky, white tubules) if disturbed while others can eviscerate (expel internal organs by rupturing the body wall). However they are able to regenerate lost body organs in time.

Figure 5.8 Sea cucumber

Phylum Chordata (Tunicates) The tunicates or ascidians, form part of the Urochordata, a subphylum of the Chordata. The Phylum Chordata includes the invertebrate tunicates, fish, reptiles, birds and mammals. Although the ascidians are invertebrates they are included in the Chordates because their larvae have a notochord (which develops into a backbone in the vertebrates), which is lost in the adults. Therefore tunicates are the invertebrates most closely related to humans. All ascidians are hermaphrodites and can reproduce asexually by budding or sexually. The larvae of tunicates resemble a tadpole, and once the larvae have settled on the substrate it loses its tail and develops into a fixed ascidian.

Tunicates are sessile filter feeders; water is drawn into an inhalant siphon and then expelled through a separate exhalent siphon. The gill slits, or stigmata, of the bronchial sac are covered in beating hair- like cilia and generate the water movement through the animal. Organic matter in the water is retained within the tunicate by a layer of mucus lining the bronchial sac. Ascidians are fierce competitors for space on the reef, and can rapidly overgrow corals, sponges and bivalve molluscs. The main predators of ascidians include starfish, polychaete worms, various fish species and flatworms. Some commensals and parasites of tunicates include

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shrimps, copepods, amphipods, molluscs, and protozoans. Tunicates are embedded in a gelatinous-looking ‘tunic’ and can occur as solitary or colonial individuals. Solitary tunicate Solitary tunicates (Figure 5.9) can form pelagic or sedentary forms. They are usually less than 20 cm in size. They come in many different colours and forms, but all can be identified by the two siphons. Solitary species are often covered in dense assemblages of sponges, other tunicates and algae.

Figure 5.9 Solitary tunicate Colonial/encrusting tunicate Colonial tunicates (Figure 5.10) can comprise of large numbers of individual tunicates or may form an encrusting mat (Figure 5.11) with openings dotted over the surface of a continuous tunic. Tunicates are often mistaken for sponges but can be distinguished as, unlike sponges, the pores will react and close when wafted. They are found encrusting over the reef. Encrusting tunicates compete with hard corals, and can overgrow them completely.

Figure 5.10 Colonial tunicate

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Figure 5.11 Encrusting mat tunicate

Lobsters

Caribbean Spiny Lobster (Panulirus argus) The Caribbean spiny lobster (Figure 5.12) is the most commonly seen lobster on the reef. It is easily identified by the sharp spines covering the head and antennae. The carapace is brown with dark spots, whilst the abdomen is brown with light spots. The juvenile has a dark brown body with purple markings, brown and white bands on the legs and a white band on the tail.

Figure 5.12 Caribbean spiny lobster, Panulirus argus

Spotted spiny lobster (Panulirus guttatus) The spotted spiny lobster (Figure 5.13) has a brownish, purple body which is covered in bright white spots, distinguishing it from the Caribbean spiny lobster. The last segment of the legs has brown stripes. Smaller than the Caribbean spiny lobster, they are not as commonly seen.

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Figure 5.13 Spotted spiny lobster, Panulirus guttatus

Spanish lobster (Scyllarides aequinoctialis) The Spanish lobster (Figure 5.14) is a type of slipper lobster. Very uncommon in Bacalar Chico Marine Reserve, the Spanish lobster doesn’t look like any other lobster, with a wide body and heavy armour. Four to five purple spots are located on the first segment of the abdomen. The body is reddish to orange brown, whilst the legs are yellow with small brown spots.

Figure 5.14 Spanish lobster, Scyllarides aequinoctialis Phylum Cnidaria (Corals, Anemones, Hydroids, and Jellyfish) The Cnidaria are a large and diverse phylum which include hard and soft corals, anemones and jellyfish. There are more than 10,000 described species of Cnidaria and they form the basis of many tropical and colder water marine ecosystems. This diverse group is united by the fact that all members are armed with stinging cells called nematocysts and the name Cnidaria comes from the Greek meaning ‘stinging creature’. The nematocysts (Figure 5.15) are barbed, harpoon-like darts tipped with poison that are discharged on contact with prey or predators.

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Figure 5.15 Diagram of a nematocyst

Cnidarians are radially symmetrical (the body is symmetrical around a central axis). Cnidarians can have one of two basic body plans, a polyp, with the tentacles and mouth facing down, or a medusa, with the tentacles and mouth facing. Some Cnidarians may pass through both life forms during their life cycle, whilst others only pass through one of the two. Some Cnidarian species consist of a single polyp, such as sea anemones and mushroom corals, whilst other species comprise colonies of polyps, such as most hard and soft corals. The basic body plan of the polyp is a cylindrical column with a ring of tentacles surrounding the only opening. The main column of the body consists of an outer layer, the epidermis, a middle layer, the mesoglea and an inner layer, the gastrodermis. There are no respiratory, circulatory or excretory organs and only a hydrostatic (water based) skeleton. Cnidarians not only rely on their stinging cells to catch prey but also use suspension feeding to capture food. Many cnidarian species also harbour symbiotic single-celled algae, called zooxanthellae, which contribute nutrients to the cnidarian. In some hard coral species it is estimated that the algae can contribute up to 80% of the daily food requirements of the coral. There are four important classes of this Phylum.

Scyphozoa (True Jellyfish)

The Scyphozoa consist of over 200 species of pelagic, free-swimming organisms that can range in size from twelve millimetres to more than two meters across. Their life cycle involves an alternation between sessile polyp phase and a free-swimming medusa stage. The Scyphozoa have only one opening, like all cnidarians, through which food and waste must be passed out. Surrounding the ‘mouth’ are usually four oral arms or tentacles which contain the stinging cells that are used for paralyzing prey and defence. The larger jellyfish prey on fish and invertebrates whilst smaller jellyfish may feed on suspended organic particles in the water. One genus of the jellyfish family, Cassiopeia spp. (Figure 5.16) has evolved an unusual feeding style. It lies upside down on the seafloor in the shallows so that its tentacles face towards the surface. The body tissue of the jellyfish contains photosynthetic dinoflagellates, which manufacture their own

[Type text] [Type text] Page 57 food and provide food for the jellyfish. Cassiopeia spp. are seen abundantly throughout the seagrass beds and mangroves in Bacalar Chico Marine Reserve.

Figure 5.16 Cassiopeia spp. (from seaslugforum.net)

Anthozoa (Gorgonians, Corals, Anemones) The Anthozoa is the largest of the Cnidarian classes, with over 6000 described species. They are exclusively marine, sedentary and can occur as individual polyps or in colonies. They have no medusoid stage in their life cycle.

Subclass Octocorallia:

The polyps have eight internal walls, and therefore have eight-fold radial symmetry, and feathered tentacles. Most octocorals produce spicules within their body tissue to provide support. The majority of octocorals are filter feeders and may also house symbiotic zooxanthellae. The order Gorgonacea, sea fans, sea rods, sea plumes (Figure 5.17) and encrusting gorgonians (Figure 5.18), are typically brightly coloured and form fan or branched shapes that align themselves perpendicular to the prevailing current. They are tougher than other members of the octocorals and have a firm internal skeleton composed of a proteinaceous material called gorgonin.

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Figure 5.17 Gorgonians (from left to right) sea rod, sea fan and sea plume

Figure 5.18 Encrusting gorgonian

Subclass Hexacorallia (Anemones and Hard Corals): The Hexacorallia is a diverse group and hexacoral polyps can vary greatly in form. They have six tentacles and internal walls, or a multiple thereof, and can have as few as 6 or as many as several hundred tentacles. The size of polyps range from less than 1 mm to greater than 1 m in diameter, and may be solitary or colonial. The order Actinaria (sea anemones) (Figure 5.19) normally form distinctive solitary polyps, with an upwards facing mouth and a flattened “foot” for attachment. Their tentacles contain the stinging nematocysts and anemones are host to many animal symbionts taking advantage of this extra protection. Anemones are host to copepods, shrimp and half crabs, which are adapted to use them for shelter.

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Figure 5.19 Anemone

The order Zoanthidea (zoanthids) (Figure 5.20) are mainly colonial. They have relatively small polyps with a double row of short tentacles that arise around the edge of the polyp. Many species are able to incorporate sand into their mesoglea4 for support. Zoanthids can reproduce asexually to form colonies or clonal 6aggregates, or through free spawning. Zoanthids will close when disturbed.

Figure 5.20 Colonial zoanthid

The order Coralliomorpharia (corallimorphs) (Figure 5.21) are similar in appearance to anemones. Most reef species harbour zooxanthellae. They can be found as solitary individuals or in small to large colonies. Corallimorphs form a flat disc with stubby tentacles radiating from the mouth. Unlike anemones, the mouth is protruding.

5 Mesoglea is the translucent, inert, jelly-like substance that makes up most of the sea creatures in the phyla Cnidaria.

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Figure 5.21 Corallimorph

Members of the order Scleractinia (hard or stony corals) are the most important reef-building animals, and there are over 2500 species worldwide. Although some species of hard coral can be easily identified there are several genera in which individual species can only be identified after examination of the skeleton under a microscope. This is partly because the morphology of coral colonies can alter depending on the environmental and biological conditions they are growing in. It is important to recognise the coral growth forms in order to describe the topography and heterogeneity of the coral reef (Table 1).

Hydrozoa (Hydrozoans) The Hydrozoa are a diverse group of organisms with about 2700 species. Most hydrozoans (Figure 5.22) are colonial and can form a variety of life forms from small, feather-like branched colonies, to large colonies with a calcareous skeleton. Most hydrozoans alternate between a polyp and a medusa stage, when they can be difficult to distinguish from a true jellyfish. Individual polyps often have specialised functions, such as for feeding or for reproduction.

Millepora spp. (Fire Coral) Millepora spp. are characterised by the hair-like stinging cells which will give nasty sting if accidentally touched. Two species are found in Bacalar Chico Marine Reserve; Millepora alcicornis (branching fire coral) and Millepora complanata (blade fire coral). Millepora alcicornis (Figure 5.23) often encrusts around sea rods and other gorgonians. Branching fire coral can be identified by the encrusting base and fine hairs present on a smooth surface. When the nematocysts retract the surface appears covered with tiny pores.

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Figure 5.23 Millepora alcicornis (branching fire coral)

Blade fire coral (Figure 5.24) grows in flat protrusions from an encrusting base. As with branching fire coral, the colour varies from tan to mustard brown, with tips appearing bleached and pale.

Figure 5.24 Millepora complanata (blade fire coral)

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CHAPTER X: ORDER SCLERACTINIA: INTRODUCTION AND IDENTIFICATION Coral reefs are composed of massive deposits of calcium carbonate, the majority of which is produced by the hard corals. Hard corals form the Order Scleractinia, part of the anthozoans, a class of animals that belong to the phylum Cnidaria. They are characterised by radial symmetry and specialised stinging cells called nematocysts. Corals are normally formed from colonies of polyps and are closely related to the sea anemones. shows the structure of a polyp. The hard corals secrete calcium carbonate around the body of the polyp which provides an external skeleton to house the polyps. The polyps sit in tiny cavities in the calcium carbonate skeleton, known as corallites, and can vary in size from a few millimetres to several centimetres. The living part of the coral is only found as a thin veneer which covers the old coral skeleton which acts as the foundation from which the coral grows. The foundation of the reef may also be composed of other calcium carbonate deposits, including shells, hard parts of crustaceans and the green algae species which secrete calcium carbonate.

Figure 6.1 Polyp and medusa forms of cnidaria.

The polyps are typically carnivorous and coral polyps consist of a ring of tentacles surrounding a mouth into which the food captured by the nematocysts is passed. The nematocysts also act as the corals defence and the tentacles also clear debris away from the mouth (Figure 6.2).

Figure 6.2 The ring of tentacles surrounding the central mouth of a coral polyp

[Type text] [Type text] Page 63 Although hard corals are found in warm and cold waters, it is only in the tropics that coral reefs develop. This is because there are two groups of corals, the hermatypic and ahermatypic corals. The main difference between the groups of corals is that most hermatypic corals contain symbiotic algae. The hermatypic corals are the reef-building corals and are found exclusively in warm, subtropical waters. Figure 6.3 shows the structure of the skeleton of a hard coral. The walls or ridges that radiate from the centre of the corallite are known as septa and are clearly visible in Figure 6.3. It is often this skeletal detail that must be examined closely under a microscope to identify several species of hard coral. The polyps of most hard corals are not visible during the day and are drawn into the skeleton. For the purpose of Blue Ventures surveying method, volunteers should learn the scientific names of all coral species.

Figure 6.3 Cross section through skeleton of a hard coral showing the structure of a corallite.

Acroporidae

The Acroporidae family (Figure 6.4) of scleractinian corals all have distinct hooded corallites. 1. Staghorn: Acropora cervicornis 2. Elkhorn: Acropora palmata

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Figure 6.4 Acropora cervicornis

6.2. Poritidae

The Poritidae (Figure 6.5) all have very small, pore-like corallites. The corallites also share walls. 1. Mustard Hill: Porites astreoides 2. Finger: Porites porites

Figure 6.5 Porites astreoides 6.3. Siderastreidae

The Siderastreidae (Figure 6.6) display “innie” corallites with protruding septa. This gives this family of corals a pitted appearance.

[Type text] [Type text] Page 65 Massive Starlet: Siderastraea siderea Lesser Starlet: Siderastraea radians

Figure 6.6 Siderastraea siderea

6.4. Agariciidae

The Agariciidae (Figure 6.7) is one of the larger families of corals. As the common names suggest, species in this family have the appearance of a cross section of a lettuce. Lettuce: Agaricia agaricites Thin Leaf Lettuce: Agaricia tenuifolia Low Relief Lettuce: Agaricia humilis Fragile Saucer: Agaricia fragilis Whitestar Sheet: Agaricia lamarcki Sunray Lettuce: Helioseris cucullata

Figure 6.7 Agaricia agaricites

[Type text] [Type text] Page 66 6.5. Astrocoeniidae The Astrocoeniidae (Figure 6.8) can be identified by their small “outie” star-like corallites. 1. 10-Ray Star: Madracis decactis 2. 8-Ray Finger: Madracis formosa 3. Yellow Pencil: Madracis auretenra 4. Blushing Star: Stephanocoenia intersepta

Figure 6.8 Stephanocia intersepta

The Figure 6.9) is a very large and variable family, including some brain corals and the Montastrea star coral complex. Symmetrical Brain: Diploria strigosa Knobby Brain: Diploria clivosa Grooved Brain: Diploria labyrinthiformis Boulder Brain: Colpophyllia natans Great Star: Montastrea cavernosa Lobed Star: Montastrea annularis Mountainous Star: Montastrea faveolata Boulder Star: Montastrea franksi Golfball: Favia fragum

6.6. Faviidae

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Figure 6.9 Diploria strigosa

6.7. Meandrinidae

All corals in the Meandrinidae family (Figure 6.10) have highly protruding septa. Elliptical Star: Dichocoenia stokesi Maze: Meandrina meandrites Pillar: Dendrogyra cylindrus Smooth Flower: Eusmilia fastigiata

Figure 6.10 Dichocoenia stokesi

6.8. Caryophylliidae The Caryophylliidae (Figure 6.11) resemble flowers, with the polyps located on long stalks 1. Smooth Flower: Eusmilia fastigiata

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Figure 6.11 Eusmilia fastigiata 6.9. Mussidae

All members of the Mussidae family (Figure 6.12) have a distinct fleshy appearance. 3. Sinuous cactus: Isophyllia sinuosa 4. Rough star: Isophyllastrea rigida 5. Ridged cactus: Mycetophyllia lamarckiana 6. Knobby cactus: Mycetophyllia aliciae 7. Rough cactus: Mycetophyllia ferox 8. Spiny flower: Mussa angulosa 9. Artichoke: Scolymia spp.

Figure 6.12 Isophyllastrea rigida

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