Last week, the Flats Ecology and Conservation team downloaded data from a large-scale passive acoustic telemetry array designed to track bonefish to their pre-spawning aggregations. A total of 61 receivers were placed around Eleuthera to track the movements of 39 bonefish and 14 barracuda that were implanted with acoustic transmitters. The research team downloaded key receivers and found schools of bonefish moving over coral reef habitats at night near tidal creeks on the East coast of Eleuthera, indicating that these fish may move offshore to spawn on the windward side of the island. Stay tuned for more updates in June.
As a bonus, while collecting receivers the team got to swim by several Elkhorn coral (Acropora palmata) colonies, an IUCN-listed critically endangered species. Elkhorn coral grows rapidly, providing significant structure and habitat for reefs throughout the Caribbean, though it is in severe decline as a result of coral bleaching, predation, storm damage, disease, and human activity. Though it was heartening to see so many healthy colonies of this critically endangered species, they are small compared to the large stands of dead elkhorn that used to thrive in the area. Our reef restoration project has begun mapping these areas and will be monitoring its growth.
Last week the Reef Ecology and Restoration team completed the March monitoring surveys of the 5 year reef study around the patches of Eleuthera. The March surveys usually call for thick wetsuit, hoods and hot chocolate. However, the water was particularly warm at 27oC, resulting in the surveys being completed in record time. Dr Jocelyn Curtis-Quick has been leading this study since 2012; she now plans to use this incredibly unique and invaluable dataset to thoroughly examine the influences and impacts that the invasive lionfish have on the patch reef ecosystem.
The Reef Ecology team has already begun the process of analysis, and Jocelyn was able to present some of these preliminary findings at the Bahamas Natural History Conference in Nassau earlier in the month. By continuing to spread and enhance the local knowledge within Eleuthera and beyond, the management of the lionfish will hopefully continue to grow.
Of the 16 patches that have been surveyed throughout the study, 8 have been designated as removal sites, and with a highly experienced team we were able to continue our contribution to the culling effort around The Bahamas and wider Caribbean. Stay tuned to hear the full results of our study and a more detailed picture of how the lionfish is making its presence felt around Southern Eleuthera. In the mean time don’t forget, You Slay, We Pay!
Nassau grouper is an economically important species in The Bahamas. Due to heavy fishing pressure, there have been marked decreases in their population sizes, especially noticeable during their spawning season. The spawning season takes place during the winter months, from December to the end of February, and the aggregations occur during the full moon. Dr. Kristine Stump from the Shedd Aquarium has been monitoring Nassau grouper in The Bahamas to track their movements to spawning aggregations, as well as to quantify the number of Nassau grouper at these historical spawning sites.
This January, the Shedd Aquarium research vessel, The Coral Reef II, travelled to Long Island, to historical spawning sites, with a representative of The Cape Eleuthera Institute on board, to assist Dr. Stump with her research. Throughout the week-long journey, the researchers on board performed dive surveys to quantify spawning stock size at one specific site. Unfortunately, very few Nassau grouper were aggregating at the site during the times of the surveys; at most 20 were noted on one survey. Illegal fishing was occurring at the time the vessel reached the site, which could explain the decreased abundance of the grouper. Poor weather conditions prevented the researchers from performing surveys on the night of the full moon, so it is unclear if numbers increased during the spawning event. Continue reading →
A spawning aggregation of thousands of bonefish (Albula vulpes) was recently filmed in South Eleuthera. Bonefish make monthly migrations of up to 80 km (50 miles) to form spawning aggregations!
CEI’s Flats Ecology and Conservation Program is currently studying the spawning migrations of bonefish, which support a catch-and-release flyfishing industry worth over $141 million annually in The Bahamas. To view our most recent publications on this economically important species, please visit our website www.ceibahamas.org.
Previous research indicates that bonefish migrate up to 80 km from shallow flats and tidal creeks to deeper water to spawn during the full and new moons. At these locations, bonefish gather in schools of hundreds to thousands of fish, forming spawning aggregations. To date, migration corridors and spawning aggregations have been located in South Eleuthera, Abaco, Andros, and Grand Bahama, and this information was used to create national parks on Abaco and Grand Bahama. The purpose of this telemetry study is to identify bonefish spawning aggregations and migration corridors around the island of Eleuthera. Information generated by this research can be used by the Department of Marine Resources and BNT to designate marine parks on Eleuthera, which will help The Bahamas meet the goal of protecting 20% of their marine environments by 2020.
This semester, the Sustainable Fisheries Team has been surveying the waters of South Eleuthera in search of juvenile queen conch. In 1993, South Eleuthera had the largest surveyed juvenile conch nursery in The Bahamas.
On the seashores of The Bahamas, it is common to see conch middens, or large piles of discarded conch shells. When fishermen return from their fishing trips, they take the fleshy meat from inside the shell and then throw that shell away. Recent conch shell midden data shows a significant increase in the harvest of juveniles. In South Eleuthera, 49.2% of the conch shells in one local midden are characterized as juveniles (lack of a flared lip).There has also been a significant decline in the number of adult conch mating aggregations in South Eleuthera.
Understanding if there is still an important juvenile conch nursery in South Eleuthera will help determine the current status of this economically and ecologically important species. Using methods created by researchers at the Shedd Aquarium, snorkelers are towed behind a boat on a manta-tow board with a Gopro attached. Images are taken continuously to document the number of conch, life stage and habitat type throughout the tow. The images are then pieced together to create a visual map of the tow. This methodology allows a rapid, accurate assessment of conch, and also documents the habitat types conch are being found in. The depths and temperature are also recorded for each tow.
During many of the surveys, only a small number of queen conch were observed, and in some tows no conch were found. But, recently, a high density of juvenile queen conch was discovered. These findings could help inform future sustainable harvesting strategies and conservation management for queen conch.
Our partner, the Shedd Aquarium, have a research team that is currently conducting further research to investigate the dispersal of conch eggs throughout the oceans currents. This further research is vital for understanding the full life cycle of queen conch and the locations of important habitats for this species.
We recommend that you only harvest conch with a fully flared lip with at least a 15mm thickness. This is when conch is considered sexually mature and can reproduce. It is important that species are able to reproduce before they are harvested, otherwise populations will most likely crash and possibly become endangered or even extinct.
Last Thursday, the Reef Ecology and Restoration team carried out our monthly growth and health checks on the Acropora fragments at the nursery site. After taking measurements on length, number of branches, and number of apical polyps of each fragment, it was found that the majority had grown in length since September. This brings us closer to our long term goal of being able to replant the coral fragments on reefs to increase populations.
To keep the coral as healthy as possible, the team carried out a deep clean, which involves brushing off any smothering algae that can cause coral mortality. Unfortunately, bleaching was seen in several fragments; bleaching is characterised by the coral turning white. This occurs when the algae that lives within corals are expelled due to stress.
One of the main reasons for this increase in stress is a rise in water temperature. We could be seeing a large increase in bleaching because this is an El Niño year. NOAA has declared this year a major bleaching event, only the third major bleaching event on record. The first global bleaching event was in 1998, during a strong El Niño that was followed by an equally strong La Niña. A second one occurred in 2010. El Niño years are characterized by changes in upwelling. Upwelling of cold currents is replaced by warmer waters and increases sea surface temperatures. With this in mind, we will keep closely monitor the nursery, and we hope to see continual growth during the next check, despite the El Niño warm waters.
Here is a link to a time-lapse video of the team cleaning the coral nursery!
Dr. Mark Hixon’s PhD students from Oregon State University returned to CEI for a fourth summer of invasive lionfish research.
As part of a long-term project, PhD student Alex Davis, and her field assistant, Kristian Dzilenski (from the University of Rhode Island), observed the home ranges of lionfish on large reefs in order to understand whether different types of habitat affect whether lionfish frequent certain areas of a reef and/or leave a reef altogether. In addition to this continued monitoring, she added an observational and experimental study on the bicolor damselfish (Stegastes partitus) and their interaction with lionfish.
This study was comprised of three components. First, she mapped the location of and tracked growth and abundance of bicolor damselfish on the same large reefs where she monitored lionfish movement. Second, she placed small PVC tubes with tracing paper inside of them called “Tunnels of Love” (TOLs) on the reefs, which allowed her to monitor egg production of the damselfish and determine if proximity to lionfish influences egg production. Third, she conducted a “model bottle” study to see if lionfish affect damselfish behavior. Each damselfish was exposed to an invasive lionfish in a clear plastic bottle, an empty bottle (for control), and a native predator, egg predator, and food competitor, each also in a bottle. The behavior of the damselfish was recorded, and a comparison of how the damselfish react to the lionfish versus the native fish and empty bottle will help us understand if damselfish see lionfish as a potential threat.
Lillian Tuttle is another PhD student from OSU, who visited CEI for 5 weeks this summer. Last summer she discovered that invasive lionfish will eat cleaner gobies, small but ecologically important reef fish that pick parasites off of other fishes. But when lionfish eat cleaners, the lionfish hyperventilates as if it ate something super spicy! She conducted a lab experiment that discovered that lionfish quickly learn to avoid the cleaner goby, meaning that this goby is one of remarkably few native fish that lionfish WON’T eat! But what about native predators? Must they also learn not to eat the cleaner goby, or are they born with an innate understanding that cleaners are friends, not food? Lillian returned to the lab and found that native graysby grouper will eat the cleaner goby and hyperventilate, just like the lionfish. But graysby are slower learners than lionfish, continuing to strike during subsequent exposures to the goby. With these kinds of friends, who needs enemies? It’s no wonder the goby has evolved a defense to makes them distasteful! Now Lillian is collaborating with chemical ecologists to identify the toxin that makes her gobies “spicy,” and she plans to defend her PhD in June 2016.
We wish the both Alex and Lillian a fond farewell and the best of luck with their Ph.D. write ups!
Sometimes all it takes is a few minutes with a trusting grouper to realize our impact on the ocean and how we can make a difference. This week, the Flats Ecology and Conservation Team at the Cape Eleuthera Institute went to retrieve a temperature logger located at the base of the Aquaculture Cage.
Located 90 feet deep near the wall of the Exuma Sound, the Cage serves as an aggregation spot for large marine creatures. Many fishermen frequent the area to catch large jacks, snappers, and groupers attracted to the cage.
Within minutes, a well-known large black grouper, affectionately named Bradley, approached the divers. Bradley came quite close to the group, turning and showing multiple hooks, wire leaders, and weights hanging from his jaw and gills. He moved in closer as Kelly Hannan, a University of Illinois graduate student, took out a pair of scissors.
Bradley investigated the scissors and seemed to decide that Kelly was not a threat. He let her cut off two feet of tangled wire leader and three fishing weights that were hanging from the right side of his mouth. Unfortunately, the scissors were not strong enough to cut the hooks out, but the team hopes to return to the Cage with wire cutters to remove them from Bradley’s jaw in the near future.
Bradley seemed to understand that no harm would come to him from these divers and was very calm throughout the procedure. He continued to follow the divers throughout the rest of the dive.
Later that week, at the same dive site, the Flats team removed over 50 feet of fishing line from a nearby reef. Another wire trace with lead weights was picked up near the base of the Cage.
Although these dives had positive outcomes, they serve as a reminder of the impacts of fishing pressure and pollution on the marine environment. Thanks to Bradley, we had a very personal reminder of our relationship with the ocean and how our actions can affect the lives of the creatures that live in it.
With the arrival of the summer interns, undergraduate and postgraduate placement students several weeks ago, CEI researcher Dr. Jocelyn Curtis-Quick has been able to tackle many different projects this summer. These projects include propagating corals at the nursery, filleting over 150 pounds of lionfish, conducting reef monitoring and conducting parrotfish feeding studies.
During March 2014, CEI installed a coral reef nursery at Tunnel Rock in collaboration with the University of Miami RSMAS and NOAA’s Atlantic Oceanographic and Metrological Laboratories and CEI Research Manager Annabelle Brooks. In the face of rapid coral population declines, growing coral through nurseries has been an initiative to replenish wild coral. The team measured the growth progress and refragmented the coral that has been steadily amassing at CEI’s nursery.
Fragmentation of coral refers to splitting of coral to help increase coral colonies and therefore increase reproduction. Half of the fragments were re-attached to the coral nursery at Tunnel Rock, and the other half were set up at a new nursery site closer to The Island School. This summer, the team will compare the growth and survival rates of the coral at these two different sites. The long-term goal is to transplant the coral frags out on the reef.
This summer the team is also being kept busy with the success of the Slayer campaign and has filleted over 150 pounds of lionfish- and has over 200 lbs to do! Over the past couple of weeks, a few local fishermen have delivered hundreds of pounds of lionfish for CEI’s “You Slay, We Pay Campaign.” These lionfish are also dissected to examine gonad development and stomach content, which can offer important insight on the invasion impacts.
Additionally, the team prepared for parrotfish behavioral research this summer. This prep has involved dive teams using a herding technique to catch the juvenile parrotfish, as well as setting up raceways in the lab to conduct a feeding behavior experiment.
A few other exciting events include three of the reef interns completing their Advanced Diving Certification and starting on their Rescue, as well visit of a teenager Earthwatch group who assisted with research for a week. Additionally, working with The Island School students to sample inland ponds and dissection lionfish was great fun. The whole team is pumped for the rest of the summer and getting much more achieved.