Prior to venturing across the Atlantic Ocean the #FieldBahamas team was divided into smaller project groups and given a topic that they would research as part of the field course. With bad weather conditions still imminent the research projects were moved forward as they were less weather dependent than the activities you will read about in Kris’ blog. For their research projects students were expected to create a hypothesis around their given topic and design a scientifically sound experiment to test it. The aim of the projects was to give students an idea of how science is conducted in the real world and an opportunity to showcase creative insight, data collection skills, and a critically thinking mind. Here’s a rundown of each group’s project, their justifications, predictions and preliminary results.
Justification: As our oceans uptake more atmospheric CO2 their pH is becoming more acidic. This process is known as ocean acidification. How different aquatic organisms will tolerate these new conditions is not well-known. Jellyfish are the oldest multi-organ animal on the planet having possibly roamed the sea for over 700 million years, demonstrating their evolutionary resilience to changing biotic conditions. Team Jellyfish aimed to test how a species of upside-down jellyfish (pictured below), common to the Bahamas, would tolerate a changing pH relative to the habitat individuals were caught. Specimens were taken from a mangrove habitat and a reef habitat and placed in tanks of varying pH, bell beat frequency was used as a measure of stress.
Predictions: It was predicted that bell beat frequency would increase across all specimens as oxygen demand increased. Furthermore, Team Jellyfish predicted that due to the harsher biotic conditions of the mangroves individuals from this habitat would have a higher tolerance for changing pH. Therefore, there would be less variation in bell beat frequency between mangrove and reef individuals.
Preliminary results: Contradictory to their hypotheses Team Jellyfish found that bell beat frequency decreased with ocean acidification. However, in all treatments the overall bell beat frequency was reduced in individuals from more unstable biotic conditions.
Justification: Mangroves is a broad term used to describe the habitat comprising mangrove trees in brackish waters where sediments collect in areas protected from wave action. Mangroves occur worldwide in the tropics and subtropics and are likened to the saltmarshes of the UK. Mangroves provide important ecosystem services for a multitude of organisms. Mangroves prevent sediment run off to reefs and seagrass which would otherwise find their growth severely inhibited. Mangroves provide nurseries for juvenile fish, shark, and turtles to develop to a size where they are capable of facing the dangers of coastal and oceanic waters. Mangroves also provide protection to local communities against severe weather conditions by taking the brunt of the blow. As communities expand, the mangrove habitat is often removed for construction uses and as a pathway to access coastal waters. Team Mangrove set out to explore how differing root densities affected the epiphytic biodiversity growing on the mangroves and thus how mangrove deforestation may affect biodiversity.
Predictions: It was predicted that epiphytic biodiversity would increase with mangrove root density.
Preliminary results: Current results are non-significant suggesting epiphytic biodiversity does not change with root density, though this may differ for other taxa such as fish.
Team Flamingo Tongue
Justification: Effects of the poor weather conditions continued to change the plans of the field course. Originally Team Lionfish, this group was given the freedom to choose their own topic, within reason, and explore a part of the Bahamian biodiversity they had found interesting thus far. With its magnificent display of colour and pattern it’s no surprise this team decided to delve into the world of the flamingo tongue (pictured below). The flamingo tongue, Cyphoma gibbosum, is a marine gastropod part of the cowrie family, it feeds on the algae covering coral species such as the purple sea fan. With mass bleaching events becoming more frequent, the future of coral in our oceans is on a precarious tightrope. Consequently, species that rely on coral such as the flamingo tongue may also be in future danger of decline. Therefore, it is important to understand the relationship this species has with corals.
Predictions: It was hypothesised that individual flamingo tongues would frequent larger sea fans and would be found on the sun facing side of the fan as their algal prey are photosynthetic.
Preliminary results: Flamingo tongues frequented larger sea fans as predicted however showed no preference regarding directionality of sunlight.
Justification: In a similar experimental design to Team Jellyfish this group set out to explore how ocean acidification will impact the survivability of sea urchins. Urchins are often described as a keystone species in food webs, dramatically affecting the structure of the web when removed. As urchins are particularly vulnerable to ocean acidification due to their calcareous exoskeleton, it is vitally important to understand how likely urchins are to survive rising pH levels. Using the West Indian Sea Egg, Tripneustes ventricosus, (pictured below) as a specimen, Team Urchin used the species’ ability to flip itself when turned upside-down as an indicator of health. The time taken for individuals to flip themselves to the upright position at varying pH levels was recorded.
Predictions: It was predicted that at greater pH changes sea urchins would take longer to flip themselves to the correct vertical position.
Preliminary results: As predicted the time taken for urchins to flip themselves increased with increasing acidity of water.
Justification: Queen conch, Lobatus gigas, abundance is declining throughout its range due to overfishing. In many places where adult conch are rare, large juveniles and sub-adults are thought to be taken before they are sexually mature. As fisherman require only the meat of this animal shells are often discarded, sometimes overboard or sometimes in a reoccurring pile known as a ‘midden’. As middens can contain thousands of conch shells, Team Conch was able to compare specimens caught recently with those caught, potentially, years before. Colour was used as an indicator of conch freshness (see colour differences below). Across five middens in south Eleuthera Team Conch measured the lip thickness of 400 queen conch shells. The sexual maturity of a conch is determined by the thickness of lip flare.
Predictions: It was predicted that the lip thickness of fresher catches would be significantly thinner than older specimens, suggesting fishing pressures have resulted in a sexually immature population in Eleuthera.
Preliminary results: As hypothesised lip thickness of queen conch significantly reduced with freshness of catch. Average lip thickness of fresh catches was 4mm, compared to older individuals at 9mm.
Justifications: Changing global climates are massively impacting reef ecosystems, causing their dramatic decline. Known to be more biodiverse than rainforests, reefs support the largest number of species of all known biomes. Future marine protected areas may aim to protect as many species as possible within reefs, therefore we must be able to identify features of a reef that make it more biodiverse. Team Reef decided to measure how fish diversity and abundance changes with reef rugosity. Rugosity, a term few of us had heard before, refers to a measure of complexity. Reefs with greater rugosity, in theory, have more habitat available for colonisation by corals and so support more fish species and numbers.
Predictions: It was hypothesised that there would be more fish species and a greater fish abundance at reefs with a greater rugosity index.
Preliminary results: As predicted there were significantly greater numbers of fish species and significantly greater number of fish at more complex reef systems.
Justification: Marine litter is a prominent scientific and global issue with its effects only just being uncovered. The surface of the iceberg that is this problem has only been scratched. It is now believed that there are 5.25 trillion pieces of plastic debris in the ocean. Shoppers worldwide are using approximately 500 billion single-use plastic bags per year. Recent advancements in the legislation of plastic use such as the ban of microbeads in the UK and the plastic bag charge are expected to reduce plastic pollution. At the cape Eleuthera institute there are multiple rules and regulations regarding the usage and disposal of plastic, aiming to keep plastic waste to an absolute zero. However, oceanic currents often drag plastic ashore. In order to aid the understanding marine litter distribution Team Plastic aimed to test how exposed and sheltered beaches differ in litter abundance. Team Plastic surveyed 8 beaches and picked up over 1500 pieces of plastic. Collected litter was then categorised as a method of determining what kinds of litter end up where.
Predictions: It was predicted that exposed beaches would contain significantly more plastic than sheltered beaches due to oceanic current pulling marine litter ashore.
Preliminary results: Results showed no significance between abundance of marine litter between beach categories. However, it is suggested that the uncommonly bad weather conditions will have affected the dataset as wind is a major factor affecting the distribution of anthropogenic marine waste. Fishing plastic was found to be more common on exposed beaches whereas food and drink waste was more dominant on sheltered beaches.
jj329 January 22nd, 2017 Bahamas, Bahamas archive anthropogenic, aquatic, Behavioural Ecology 2016, Biodiversity, conch, conservation, Coral, Destruction, development, ecology, Field Course Fornight, FieldBahamas, invertebrates, jellyfish, marine, ocean, oceanacidification, travel, univeristyofexeter, urchins