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stingrays

Dr Owen O’Shea visits the Florida Fish and Wildlife Conservation Commission

The ongoing collaboration between the Cape Eleuthera Institute and the Florida Fish and Wildlife Conservation Commission (FWWCC) was recently further endorsed with a visit by Research Associate Dr Owen O’Shea to the FWWCC headquarters in St. Petersburg, Florida. Much of Dr O’Shea’s work on stingray genetics is in collaboration with Dr Liz Wallace, postdoctoral research fellow at the commission and so this trip served as an analytical opportunity for Owen to conduct lab work with Dr Wallace in order to process DNA samples collected over the past 12 months. IMG_4408

This research project is in the final stages of completion, after Owen collected 70 samples from the rare, elusive and recently re-described Caribbean whiptail stingray Styracura schmardae across multiple spatial scales in the central Bahamas. This work is the first of its kind in this species, and will attempt to discern dispersal potential and gene flow across restricted temporal periods, for example, in assessing sibling and parentage relationships, rather than an historical radiation.

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This work is important, because in fragmented habitats, such as The Bahamas, barriers to gene flow and dispersal are realized, particularly among island chains, separated by deep ocean basins. This provides challenges for live bearing fish species, further exacerbated by conservative life histories; so understanding these dynamics and potential migratory corridors will enable us to further discern the importance of these coastal environments.

Prey discrimination in yellow rays: project update

In the last month, Research Technician Maggie Winchester began behavioral trials of yellow rays (Urobatis jamaicensis) as part of her independent project, under the supervision of Dr. Barbara Wueringer of James Cook University, Australia, and Dr. Owen O'Shea of the Cape Eleuthera Institute (CEI). This project aims to address the capacity of the electric sense utilized by all elasmobranchs, as it pertains to their foraging strategy. Specifically, Maggie and the team using experimental manipulations to assess to what extent prey type can be ‘discriminated’ by isolating electric sensory mechanisms alone.

Yellow ray close up

The yellow ray is one of the most ubiquitous and commonly encountered elasmobranchs throughout the Caribbean region and is a regular visitor to the shelf and patch reefs adjacent to CEI. It is a small-bodied benthic ray that lives in seemingly mixed sex aggregations and is very easy to catch in shallow water with two dip nets by snorkeler. So far, the team has successfully captured and transported 19 rays to the wet lab at CEI, where they have all undergone behavioral trials, and been successfully returned to their capture sites after 24-hours observation.

A yellow ray in one of our wet lab holding tanks awaiting trails

During the experimental trials, individual rays are presented with two concealed prey types that are known to be part of their diet based on a study by CEI currently in review for publication. These two prey choices are concealed in agar, masking visual, chemical and gustation cues and allowing for detection solely through electro-sensory means.

This work will allow a clearer and more concise evaluation on the specific role the ampullae-lorenzini have in discriminating a specific type of prey, and raises questions on whether these rays actively choose one prey type over another.

European Elasmobranch Association meets in Bristol

Over the weekend of the 28-30th October the European Elasmobranch Association met for its annual conference hosted by The Shark Trust in Bristol, England. Daniel Montgomery, a graduate student with Newcastle University, attended the conference to present his research focussing on the influence of temperature on habitat use of southern stingrays. This research was conducted at the Cape Eleuthera Institute between February and June 2016 in collaboration with Dr. Owen O’Shea and formed a research class for the spring 2016 Island School semester. 15058617_1208845099181448_455708229_n (1)

The conference was attended by 160 delegates from 22 countries. Over the three days 67 oral presentations were delivered on a variety of themes with talks giving an overview of current research being conducted around the world. The conference is known for its broad focus with notable presentations ranging from taxonomy and isotopic analysis of deep sea sharks to the classification of nursery habitats in tropical mangroves.  In addition keynote addresses were delivered on subjects focusing on improving management and conservation of elasmobranchs globally. The conference gave a fantastic opportunity to meet other shark and ray researchers and promote the important work conducted at the Cape Eleuthera Institute alongside other research institutes.

Dan has just been awarded a pass with distinction from Newcastle University for his thesis titled Temperature preference and thermal niche of the southern stingray (Dasyatis americana) in South Eleuthera, The Bahamas. Dan is currently working towards his PhD at Exeter University and we wish him every success!

Graduate student update from the Stingray Research Group

Molly Meadows and Ethan Wrigglesworth have joined the team as part of the Masters of Research data collection from Exeter University in the UK, under the supervision of Dr. Owen O’Shea and Dr. Lucy Hawkes. The university has been visiting CEI every January for three years as part of their field course module, creating a fantastic bond between the two institutions. So it is very exciting to have students from Exeter studying their Masters with CEI for the very first time, further expanding our relationship and connection. Ethan, Molly and the stingray team work up a large female southern stingray.

Both Molly and Ethan are researching stable isotope analysis on the two species of stingrays here in Eleuthera, the Caribbean whiptail and southern stingrays. Stable isotopes can be used to peek into the diet and ‘trophic status’ of an organism over different timescales. It basically follows the general rule of “you are what you eat”; all organic tissue has an isotopic value and, once ingested, that value can then be identified within the consumer's body tissues. They will be collecting body tissue samples from both species of stingray, as well as diet and habitat samples, all of which will be analysed back at Exeter’s facilities in the UK. They will also be studying captive rays in the wet labs here at CEI, discerning how quickly isotopic values from manipulated prey sources are assimilated into different body tissues.

Molly and Ethan brief an educational program before going out into the field (Photo by Catherine Argyrople)

This research forms part of The Island School Applied Scientific Research Class and students will be directly assisting with data collection whilst producing a side project on dietary partitioning between the two ray species.Stingrays are remarkable, ancient creatures, which play key roles as mesopredators and bioturbators within their environment, keeping ecosystems stable and healthy. Despite this, not much is actually known about this group of around 90 species, particularly the species focused on in this study. Therefore, any research on these creatures is vital, not only for the conservation of the individual species, but for the systems they inhabit as a whole. Understanding these stingrays place in the food chain will help quantify their impacts on local fisheries and ecosystems allowing more effective conservation methods to be employed.

A female southern stingray is released after being sampled for stable isotopes

 

American Elasmobranch Society meets in New Orleans

The American Elasmobranch Society recently met in New Orleans for their annual meeting, attended by an international collective of shark and ray scientists to discuss current and ongoing work in this very eclectic field. The Cape Eleuthera Institute was represented by Oliver Shipley and Dr. Owen O’Shea of the Shark Research and Conservation Program, both giving oral presentations to a wide range of scientists from all over the world. Oliver’s presentation focused on novel methods for post-capture release of a small bodied deep-sea shark – the Cuban dogfish - and how novel approaches may increase survivorship during by-catch events. Owen spoke of the recently ‘re-discovered’ Caribbean whiptail stingray and discussed its contemporary distribution in The Bahamas and implications for management. Dr, Owen O'Shea during his presentation on Caribbean whiptail stingrays

The week spent in New Orleans was a huge success, with the convening of several meetings and discussions pertaining to the global fin print project and a whole day dedicated to a global sawfish research symposium. Among some of the other stand out talks were the very first satellite tracking of manta rays conducted in Sudan, juvenile white shark movement in California and challenges for management of large ranging sharks, such as the great hammerhead and oceanic whitetip. It was a fantastic week with many old relationships rejuvenated, and the fostering of new ones cemented, with collaborative studies already having been discussed.