Senior thesis/ Dissertations
Marine ecology topics
IH201 Competition within and between the dominant coral reef benthic taxa (Weeks 3 – 9; need to have completed IH112 and be dive trained)
As reefs around the world face increasing anthropogenic stress and the abundance of Scleractinians (hard corals) decline, there is the potential for increased abundance of other spatially competitive benthic taxa (or more resilient Scleractinians). Phase shifts from coral-to-algal –dominated reefs have been well documented in the Caribbean but so far this has not been observed in the Wakatobi despite significant declines in Scleractinian coral. Alternatively the most degraded reefs surrounding Hoga Island have experienced an increase in an aggressive colonial ascidian and a smothering sheet-like sponge. These two alternative spatial competitors are members of the five most dominant spatially competitive sessile taxa on Indo-Pacific reefs; Scleractinian corals, Alcyonacean corals (soft corals), Porifera (sponges), Ascidians (tunicates) and Algae. Significant spatial competition occurs both between and within these taxa and is a considerably important mechanism influencing the community structure of coral reefs. Given the potential for shifts to alternative stable states to dramatically alter the ecology of the system by decreasing biological and physical complexity, it is vitally important that more research is conducted into competitive interactions within and between reef benthic taxa. This project will investigate the spatial associations, potential competitive interactions and outcomes amongst the five dominant reef benthic taxa and assess how coral reef function may change as a result of changes in abundance of these taxa.
IH202 The abundance, diversity and distribution of Nudibranchs in Indonesia (Weeks 3 – 9; need to have completed IH112 and be dive trained)
Molluscs are the most abundant group of animals on coral reefs, comprising up to 60% of all marine invertebrate species. Nudibranchs are one of the most diverse groups within the phylum but ecological knowledge of these charismatic species and specifically data concerning their true diversity, abundance and distribution is very limited. Studies in to the extremely photogenic Nudibranchs are of critical importance to the Wakatobi, which is increasingly becoming recognised as one of the best coral reef dive sites in the world particularly for underwater photographers. Unfortunately before Operation Wallacea established their research facility on Hoga Island, an expedition team removed many specimens for museum collections and since that point numbers have been low. However anecdotal evidence suggests that populations are recovering and now represents the perfect opportunity to gain a much greater understanding of the ecological needs of Nudibranch species, their habitat preference, feeding ecology and those factors that drive their distribution as well as abundance. Due to their life history traits such as low fecundity and low dispersion, Nudibranchs are not very resilient and thus detailed knowledge of their ecology are needed so group specific conservation strategies can be produced and recommendations made to marine park authorities.
IH203 The ecology of Anemonefish in Indonesia (Weeks 3 – 9; need to have completed IH112 and be dive trained if incorporating a diving element)
One of the more conspicuous groups of fish on tropical reefs are the anemone fish. Anemone fish are collected for the aquarium trade and depend entirely on the presence of host anemones. This mutualistic relationship is well known but preliminary investigations within the Wakatobi suggest that coexistence between different species of anemone fish within a single host is more common than in other areas of the world. A deeper understanding of coexistence along with the factors that influence the distribution of host anemones is required. Observations also suggest that within a single host anemone different species of fish may separate themselves in space and utilize different parts of the anemone thereby reducing competition and aggressive interactions. The dominant species of fish appear to occupy more of the host anemone when compared to less aggressive species or a species that has arrived at the anemone after the original occupying species. Thus there is much to address within this research area and generally speaking there is a data gap in this bioregion. Research could include detailed investigations in to the factors that drive the abundance and distribution of anemone hosts, and patterns of coexistence across sites with different host availability along with studies that examine the intricacies of the coexistence and the apparent sharing of host resources.
IH204 The behaviour and functional role of reef fish cleaners in Indonesia (Weeks 3 – 9; need to have completed IH112 and be dive trained if incorporating a diving element)
Cleaner fish play an important role on coral reefs around the world. Recent studies have shown that the health of reef fish and the biodiversity of reef systems increase when cleaners are abundant. The Wakatobi Marine National Park is unusual in that three species of cleaner wrasse are present on its reefs. The most abundant is the Bluestreak Cleaner Wrasse (Labroides dimidiatus), which has been fairly well studied but much less effort has focused on the ecology of the other two cleaner wrasse species; the Blackspot Cleaner Wrasse (Labroides pectoralis) and the Bicolor Cleaner Wrasse (Labroides bicolor). This project could be divided into a number of different studies that aim to fully characterize the ecology of the different cleaner species whilst also evaluating the role they play on reefs of different quality. In particular studies could compare the clients of the different species and whether or not the relative importance of the different species, in terms of service provision, changes with environmental conditions and fish assemblage. Long-term monitoring data is available that could also be used to examine how the abundance of the different cleaners has changed over time possibly in relation to changes in habitat quality and total fish richness and abundance.
H205 The ecology and biology of shallow subtidal patch reefs in Indonesia (Weeks 3 – 9; need to have completed IH112 and be dive trained if incorporating a diving element)
How stable are reef communities over time? What changes are occurring and over what time scales? What are the responses of fish communities to changes in benthic cover? Coral reefs are dynamic ecosystems and may actually exist in multiple stable states. Permanent transects have been used to successfully document changes in benthic cover, but assessing changes in mobile organisms are more difficult. However, smaller patch reefs sometimes referred to as bommies provide an ideal template to evaluate changes in mobile organisms, as they tend to house a greater number of resident species. Coral patch reefs situated in lagoonal areas backward of the main reefs may also facilitate the daily migration of reef fish to other coastal habitats such as seagrass and mangrove forests. Consequently and apart from being an ideal model system to investigate the drivers of reef biodiversity, these patch reefs are of major ecological importance. Several projects could be developed in this field to assess the ecological and functional roles of such patch reefs, and also to identify the key environmental and biological drivers of patch reef biodiversity. This research is increasingly becoming more important as such patch reefs are often targeted for coral mining activities and are therefore are at real threat from human induced degradation.
IH207 Environmental impact and feeding habits of the Crown of thorns starfish Acanthaster planci (Weeks 3 – 9; need to have completed IH112)
Acanthaster planci are corallivores and voracious predators of coral reef ecosystems, spending approximately half their lifetime feeding. An individual adult is able to feed continuously for up to 9 hours at a time by extruding its stomach inside-out over coral polyps. Despite this insatiable feeding technique a healthy coral reef with around 50% coral cover can sustain between 20-30 individuals ha-1, however outbreak densities of up to 1000 ha-1, can destroy a reef system in months.Due to the potentially destructive nature of A. planci it is very important to establish the extent to which the starfish is affecting reefs within the Wakatobi. Baseline surveys performed in 2011 and 2014 have shown that A. planci populations in the Wakatobi can vary dramatically in abundance temporally; therefore it is essential to regularly monitor these populations to define any outbreak events. This can be achieved by assessing current population densities in relation to previous A. planci surveys and through monitoring their feeding habits and destructive potential. This study will involve diving or snorkelling based population surveys combined with behavioural investigations aimed at identifying the most favoured coral prey and therefore the species of coral that are most at threatened by the starfish within the Wakatobi.
IH208 The physical and biological structure of coral reef systems (Weeks 3 – 9; need to have completed IH112 and be dive trained)
Coral reefs are the most biodiverse marine systems which is largely due to the physical complexity of the habitat. Many different taxa add to the complex structures that characterize reefs but the predominant reef builders are the hard corals. Hard coral colonies are highly variable in both size and shape that is in part a species-specific trait but is also environmentally regulated. Under different environmental conditions, such as light and exposure, colonies grow in different shapes and thus the physical complexity of a reef varies greatly. The variable complexity provides diverse habitats for the numerous species that live on a reef system and the higher the physical complexity the more diverse the biological community. Unfortunately due to numerous factors such as reduced water quality and high sedimentation and turbidity, coral reefs around the world are becoming less complex and generally flatter. We know that such changes will negatively impact biodiversity but we as yet do not know which species will be most affected and how the functional ecology of reef systems will change. Numerous studies could be implemented under this topic including both small and large spatial scale surveys, characterization and environmental regulation of reef architecture, the association between reef complexity and fish biodiversity, as well as the functional ecology of fish communities existing within reefs of different complexities. We must better understand the consequences of a global reduction in the physical complexity of reef systems and in particular how biodiversity, the functional ecology and fish biomass will be affected.
IH209 Adaptations of cephalopods to extreme environments (Weeks 2 – 9)
Dwarf cuttlefish and pigmy squid are renowned for their intelligence and complex behaviours. As key predators, they shape the density and diversity of crustacean populations in the shallow intertidal waters of the Wakatobi Marine National Park. Both cephalopods can be found in areas prone to severe shifts in temperature, salinity and oxygen, yet surprisingly little is known about the physiological adaptations that allow the molluscs to survive such a wide range of environmental extremes. Dissertation projects will address questions related to habitat utilization, and effects of changing environmental conditions on population distribution and carrying capacity, by quantifying physiological and/or metabolic responses to abiotic extremes experienced in their environment. The results will provide important ininformation into the adaptations used by shallow-water cephalopods to survive capricious environments, as well as aid in developing effective conservation and management strategies.
IH211 The eco-physiology of juvenile reef fish (Weeks 2 – 9)
The reefs surrounding Hoga Island off southeast Sulawesi are some of the most beautiful in the world, and are home to hundreds of reef fish species. Ironically, several reef fishes spend the first part of their lives in seagrass or mangrove nursery habitats where conditions are very different from the reef. Perhaps it is not surprisingly therefore, that the physiology of juvenile fishes can differ greatly from adults. Many previous studies have spotlighted adaptive differences between adult reef species, but far fewer have focused on ontogenetic changes in physiology of reef species. Dissertation studies aim to improve our understanding of this often overlooked area of investigation by quantifying physiological tolerance and metabolic changes that occur as juveniles recruit to the reef environment.
IH212 Can animals already living at extreme temperatures survive climate change? (Weeks 2 – 9)
Fishes and invertebrates living in tidally influenced seagrass or mangrove habitats experience extreme and often arbitrary shifts in water temperature as tidal and insolation patterns change over time. Add to this, the fact that some climate models predict an increase of up to 4°C in the western Pacific, and it becomes clear that some thermally-sensitive species may be at risk of extirpation. Indeed, previous studies suggest that some intertidal are already living at temperatures near their upper thermal limit. It’s likely therefore some groups may be extirpated from part or all of their range as sea surface temperatures increase over the coming decades, whereas others may be unaffected. The resulting shift in community structure could have far reaching ecological consequences. Unfortunately, relatively little is known about the thermal ecology of most intertidal animals or how they may fare under a more extreme environmental thermal regimen. Dissertation studies quantifying thermal tolerance or capacity acclimation limits of important species (e.g., top predators or forage species) or keystone groups (e.g., damselfishes or cephalopods) are necessary to assess how well adapted these groups are to changing temperatures. In addition, thermal profiles of mangrove/seagrass areas can be mapped, and the data merged with tolerance data to identify fish groups most likely to be impacted by rising sea temperatures. The results can provide important insights into the ecological changes that may occur in shallow intertidal regions as sea surface temperatures increase.
IH213 Thermal induced rapid coral mortality in Indonesia (Weeks 3 – 9; need to have completed IH112 and be dive trained if incorporating a diving element)
Coral reefs are perhaps the most sensitive and important ecosystems on planet Earth. With threats of global climate change, ocean acidification, and increased human impacts, it is predicted that as many as 33% of coral species will become extinct in the wild over the next 50 years. Some coral species are likely to be more eurythermic (i.e., survive over a wide range of temperatures) than others; however, empirical data on acute thermal mortality of coral from periodic natural events (e.g. during El Niño years) are largely lacking. Dissertation projects comparing key coral species from a range of sites could be useful in predicting how temperature extremes may affect the biological and physical structure of reef systems. While the experimental component of the research would be laboratory based, researchers may also find it useful to include diving/snorkelling reef survey in their results.
HB239 Tracking the recovery of a keystone urchin species and its role in reef restoration (Join this project 17 June or 1 July; need to complete dive training and HU106 or HT108)
Under natural conditions, the sea urchin Diadema antillarum is the most important herbivore on Caribbean coral reefs, and is therefore considered a keystone species. However, a disease in the 1980s caused the death of an estimated 98% of individuals throughout the region. This mass mortality event had a devastating effect on reef health, driving subsequent phase shifts to algal dominated benthic communities. Recovery has been extremely limited throughout the Caribbean, with populations on most reefs still severely depleted, and Utila is a classic example of this. Remarkably, the Banco Capiro reef system in Tela Bay has a population density of D. antillarum at astonishingly high levels. It also boasts extremely high benthic reef health, despite historical overfishing leading to a complete collapse of the fishery. Since its recent discovery, Operation Wallacea scientists began detailed population studies in 2013 and this project will build on this. The primary objective is to quantify changes in the abundance, biomass and population structure of D. antillarum on the reefs of Utila and Banco Capiro. Further data will assess the potential roles of competition, predation and environmental factors in driving the recovery on Banco Capiro through the study of benthic and fish community assessments.
HB240 Spatial and temporal patterns in fish community structure and biomass on contrasting reef systems in Honduras (Join this project 17 June or 1 July; need to complete dive training and HU106 or HT108)
The reefs around Utila and Tela Bay offer a unique opportunity to study various aspects of fish community structure and population dynamics on Caribbean coral reefs. Reef fish populations are subjected to a huge variety of different pressures and variables, both natural and human, that dictates their abundance and diversity. Many of these variables are not fully understood. On Utila, overfishing has long been a problem, whilst degraded reef habitats have limited the carrying capacity for fishery recovery. However, the island boasts a gradient of reef habitats to explore the drivers of fish population density and community structure. The reefs of Tela Bay have been subjected to extreme overfishing in the past, which has led to a complete collapse of the fishery. This ultimately led to a decline in fishing pressure that, along with the extensive mangrove systems in the bay, has provided Tela with the potential for rapid fish biomass recovery. Dissertation projects will use cutting edge stereo-video technology, which allows accurate biomass assessments of reef fish communities. These data will be combined with additional benthic habitat surveys using underwater video transects as well as environmental variables to investigate the main drivers of variation in reef fish community structure. Other projects could focus on temporal trends in overall fish biomass at both sites using data from previous research seasons.
HT241 Feeding ecology and habitat preferences of ecologically important Diadema antillarum sea urchins (Join this project 17 June or 1 July; this project is predominately laboratory based but need to complete HT108 or HT109)
It remains a mystery to scientists why the sea urchin Diadema antillarum has still not recovered, even 30 years after an unidentified pathogen killed up to 99% of individuals throughout the Caribbean. The herbivory this species naturally provides to the region’s coral reefs makes it a keystone species and the ecological cost of their mass mortality has been enormous. It is therefore considered one of the top priorities for marine conservation in the Caribbean. Despite this, research into a lack of recovery remains worryingly low and many important questions remain unanswered. On the Banco Capiro reef system in Tela Bay, Honduras, a healthy population of Diadema exists and the health of the reef is one of the best in the Caribbean, likely as a direct result. This project will remove individual urchins from the reefs of Banco Capiro and collect behavioural and environmental tolerance data back at the Tela Marine Research Centre. Key questions include food preferences, to determine the types of algae these urchins prey upon, as well as quantifying their preference for structurally complex refuges to avoid predation and other pressures. This project is predominately based on land in a small wet laboratory, but could involve some diving for sample collection and to map natural movements of urchins on the reefs to explore home ranges.
HU242 A critical comparison of assessment techniques for surveying Caribbean coral reef ecosystems(Join this project 17 June or 1 July; need to complete dive training and HU106)
The design of specific coral reef survey and monitoring protocols depends on a range of factors. Ranging from available funding and manpower, to the expertise of participants and the level of detail required to meet pre-defined goals. Decreasing data resolution and number of replicates can increase the speed of data collection, but this has negative consequences for data reliability and the ability to answer more complex questions. Due to the heavy reliance on SCUBA, traditional methods focus on in situ data collection, meaning time becomes a significant limiting factor due to restrictions on totol time spent underwater each day. However, the emergence of affordable technological alternatives to traditional coral reef monitoring techniques has greatly increased the potential efficiency of data collection. Benthic surveys to study reef habitat quality can be conducted using underwater videography, while fish surveys can be conducted using state of the art stereo-videography to provide accurate biomass as well as abundance. These techniques allow scientists to analyse footage back on land, meaning more replicates can be completed on a single dive. This dissertation will critically compare a range of coral reef survey techniques, exploring their strengths and weaknesses, to better inform researchers and conservation managers when designing reef monitoring strategies in the Caribbean.
HU243 Depth distributions and bathymetric connectivity of coral reef fish (Join this project 17 June or 1 July; need to complete dive training and HU106, this project can also be land based)
Most coral reef research focuses on shallow water habitats and their ecological processes. A good example of this is the habitat connectivity exhibited by fish migrations between coral reef, seagrass and mangrove ecosystems. However, coral reefs extend well beyond the limits of recreational diving, with mesophotic coral reef ecosystems (MCEs) extending in some areas to over 100m. These reefs are beyond the reach of most researchers, and therefore very little is known of the community structure at these depths, and what level of habitat connectivity exists between MCEs and their shallow counterparts. By working alongside a small team of technical divers and remotely deployed camera systems able to sample MCEs, students who are diving on this project will help collect the shallow data component through a range of fish and benthic monitoring techniques, and ultimately have access to both data sets for use in their dissertations. Non-diving students will operate and analyse footage from remotely deployed baited camera systems. Specific questions could include an assessment of total biomass at varying depths, or a more detailed analysis of fish community structure between a range of habitats. The ultimate aim of this project is to investigate the importance of deeper coral reef habitats for conservation management, and data collected will be used to inform the conservation framework on Utila.
HU244 Competition for space between benthic organisms on Caribbean coral reefs (Join this project 17 June or 1 July; need to complete dive training and HU106)
Scleractinian corals are the ecosystem architects of highly biodiverse and productive coral reef biomes. However, on many reefs around the Caribbean, numerous factors have negatively impacted the ability of corals to thrive as they once did, which has severely altered the way competition for space takes place on these reefs. In particular this has commonly led to an overgrowth of macroalgae and the threat of an ultimate phase shift to an alternative stable state lacking the structural complexity to support the high diversity of fish and invertebrates which a healthy coral reef is famous for. This dissertation will study the interactions between Scleractinian corals and other groups of benthic organisms such as macroalgae, sponges and soft corals to assess how these interactions are varying between reefs with different levels of impact. It could also focus specifically on the coral community and study how competition between coral colonies varies with increasing impacts to try and gauge which corals are most likely to dominate the system in future years.
HT245Uncovering the unique ecosystems of light-limited coral reefs in Tela Bay (Join this project 17 June or 1 July; need to complete dive training and HT108)
The coral reefs of Tela Bay are truly unique and pose a number of ecological questions with important implications for coral reef conservation throughout Honduras and the rest of the Caribbean. The main reef in the bay, known as Banco Capiro, boasts a coral cover of approximately 70%, which is higher than almost anywhere else in the entire Caribbean and even higher than many reefs in the Indo-Pacific. Nearby patch reef systems, however, are more representative of Caribbean reefs, being dominated by macroalgae after the occurrence of phase shifts, although even these sites are showing early signs of recovery. Another distinct difference between the reefs of Tela Bay and elsewhere is the increased turbidity, which reduces visibility but importantly reduces the quantity and quality of light reaching the benthic community. This phenomenon is believed to protect sensitive corals from the dangers of high light stress, an idea known as the refuge hypothesis. In short, the reefs of Tela Bay are ecologically mysterious, and this project will attempt to better our understanding of the biological and ecological processes taking place on the coral reefs of Tela Bay, in order to better inform conservation managers of how the corals are able to thrive to such an extent. Data will include a benthic assessment of a number of reef sites to investigate patterns in benthic cover, coral species diversity and variation in environmental conditions. Access to previous data from the first detailed assessment of Banco Capiro in 2014 will also be available to explore evidence of long-term variations in reef health and function.
HU246 An assessment of coral health on Utila’s fringing reef system (Join this project 17 June or 1 July; need to complete dive training and HU106)
Global climate change is having a serious impact on coral reefs, with the health of both hard and soft corals under threat from a range of factors. These include coral bleaching and disease, both of which reduce the health of a colony and can ultimately lead to the death of the coral. Modern pollution levels are believed to be responsible for an increased frequency of disease, whilst a number of factors are known to cause coral bleaching, most famously increased water temperature. Other impacts on the health of coral colonies include bioerosion by macroinvertebrates and the activity of coralivores such as parrotfish. These impacts are evident on reefs around Utila, and are adding to the suite of factors negatively impacting the health and viability of important coral communities. This dissertation will explore the extent of various coral mortality impacts on reefs around Utila, focusing on trying to identify patterns in their occurrence and severity. It could also look for variations in susceptibility between different taxonomic groups down to species level, and predict which species are most likely to survive under current conditions.
HU249 Thermal ecology, tolerance, and temperature preference of coral reef and mangrove species in Utila, Honduras (Join this project 17 June or 1 July; need to complete HU106 or HU107)
Temperature has a profound effect on survival, growth, reproduction and distribution of ectothermic animals. Indeed, temperature is often referred to as “The Abiotic Master Factor”. While ectotherms living in thermally capricious, shallow water environments exhibit a range of biochemical, molecular, or cellular mechanisms to ameliorate short-term exposure to temperature extremes, it is less clear how these organisms with respond to widespread increases of up to 4ºC in average sea surface temperatures. Dissertation studies measuring key ecophysiology attributes such as thermal tolerance and thermal preference would help define the range of physiological elasticity of shallow intertidal animals, as well as provide a better understanding of the interspecific variation seen in these animals. Researchers will have the opportunity to conduct thermal laboratory experiments with a variety of coral reef, seagrass meadow, and mangrove species. These studies would provide important information for designing effective conservation and management strategies for mangrove and seagrass dependent species facing global climate change.
YA296 Abundance of Damselfish and their impact on coral reef health through the promotion of algal growth (Weeks 3 – 9; must be dive trained and have completed YA104)
Damselfish are a small territorial family of fish, and one of the most common residents of Caribbean coral reefs. As herbivores they rely on algal food sources, and they exhibit the fascinating behaviour of actively farming algae within the confines of the territories. This behaviour can include weeding of undesirable algal species to promote more palatable alternatives, and the exclusion of competing herbivores. As a result, damselfish play an important role in sculpting the benthic community found on reefs, with the dominant benthic communities often differing significantly between territory and non-territory areas. With the increasing dominance of macroalgae on the world’s coral reefs causing widespread concern amongst conservation scientists due to the threat of phase shifts to long term reef survival, this behaviour takes on added significance. This project will begin by describing the damselfish community structure on reefs around Akumal Bay, in terms of diversity, abundance and biomass. Subsequently, the benthic community present in territory areas will be compared to non-territory areas, as will evidence of coral mortality, and the varying impacts of different damselfish species will be compared.
YA297 Monitoring coral health using photographic techniques (Weeks 3 – 9; must be dive trained if collecting data by diving and have completed YA104)
Traditional visual approaches to coral research yields basic data suitable for answering broad questions on ecosystem health and habitat variability. However, the emergence of technological alternatives to simple in situ observations give many more options and greatly increase the breadth of questions that can be addressed. At the most basic level, photos can be analysed after a dive to confirm species identifications and confirm signs of coral impacts such as disease. If scale bars are added to the frame as reference points, analysis can be expanded to include accurate length and surface area calculations. This project will use traditional underwater transect techniques to characterise the abundance of live coral on reefs around Akumal Bay, Mexico, at varying depths. Size referenced photographs will then be taken of each coral colony along each transect. Once back on land, these photographs will be analysed for features such as total colony size (surface area), polyp density, disease instance, evidence of bio-erosion or bleaching, and the proportion of the colony impacted quantified. These data will allow size structures for individual coral species to be constructed, and those species most susceptible to anthropogenic impacts identified. Results can be compared to general abiotic and biotic factors at each site to explore how environment sculpts the coral community. Information will help ultimately be used to inform local management plans.
CU311 Manatee ecology in Cuba (Weeks 1 – 6)
Manatees are large marine mammals found predominately in shallow coastal tropical environments between the Caribbean to West Africa. This has brought them into regular close contact with humans, and as a result they have been particularly impacted by damage from boat traffic and through loss of natural habitat due to coastal development. This project forms part of a long-term investigation into manatees on the Isle of Youth, Cuba, led by scientists from he University of Havana. Data collection focuses on a network of lagoons and channels in an extensive mangrove forest, and is entirely boat based. Lagoons will be surveyed for manatees using a combination of visual transect and side scan sonar techniques, with abiotic variables measured at regular intervals to characterise the environmental parameters present at each site. Once located, individual manatees will be herded towards a net, and captures attempted. Successful captures will allow morphological and physiological measurements to be taken. In addition, faecal samples will be collected to allow analysis on diet and parasite loading of the local manatee population. Temporal data are also available to study long-term trends in manatee numbers in the area.
CU312 Managing the Caribbean lionfish invasion (Weeks 1 – 6; need to be already dive trained or complete dive training in Week 1)
Lionfish are an invasive species in the Caribbean, and are having a devastating impact on local fish communities throughout the region. Introduced, believed to be by accident, in the early 1990s, lionfish have spread extremely quickly and are expected to soon be found as far as New York and South America. Their success is down to a number of factors, including their high reproductive rate, generalism in terms of both diet and habitat, and a lack of natural predators. They are now considered to be one of the greatest threats to the future of Caribbean coral reefs and their fish communities. Management approaches to dealing with the lionfish invasion are limited, with one of the most common being direct removal via spear fishing. This relies on regular visitation to individual reef sites, as studies have shown full recovery of lionfish only five months after complete removal. This dissertation will compare sites of intense lionfish removal to those with low levels of hunting. Data will be collected on abundance and size structure through SCUBA surveys. Lionfish will also be removed and dissected to provide morphological, physiological and gut content data to explore variations between contrasting populations. Additional studies could explore changes in wariness to divers between populations heavily hunted and those less exploited by humans.
CU313 The ecological importance and current status of Acropora cervicornis corals in the Punta Frances National Park (Weeks 1 – 6; need to be already dive trained or complete dive training in Week 1)
Reef-building corals are the ecosystem architects of the most diverse ecosystems in the ocean, tropical coral reefs. They lay down a calcium carbonate skeleton that, generation by generation, leads to the large complex 3D structures we see on reefs today. In turn, this structural complexity supports productive and diverse communities of fish and invertebrates. Those coral species that provide the most complex structures are therefore the most valuable, but they also tend to be the most susceptible to impacts. In the Caribbean, Acropora cervicornis and Acropora palmata are the most complex coral species, forming branching growth forms, but this makes them easily damaged and destroyed and, as a result of recent intense hurricane activity, they are almost completely absent on many reefs around the Caribbean. In the Punta Frances National Park, Cuba, A. cervicornis in particular is present in unusually high abundance. This project will work on these reefs to better our understanding of the abiotic and biotic factors facilitating the survival of these vital coral species, their current health in Punta Frances through assessments of mortality incidences, and also their ecological importance by surveying the fish and invertebrates associated with them compared to other, less structurally complex coral species. Data will be collected by SCUBA using a range of techniques.