Research Questions:

  1. What sounds do southern stingrays respond to, and at what sound level?

  2. Do elasmobranchs exhibit a behavioural avoidance response to noise (boat, cruise or plane)?

  3. Is there a difference in behavioural response or threshold between wild and domestic stingrays?

  4. Is there a difference in ear morphology between male and female stingrays?

Bonfil, R. (1994). Overview of world elasmobranch fisheries (No. 341). Food & Agriculture Org.

Jacoby, D. M., Croft, D. P., & Sims, D. W. (2012). Social behaviour in sharks and rays: analysis, patterns and implications for conservation. Fish and Fisheries, 13(4), 399-417.

Megan Mickle - University of Windsor, ON, Canada

Project supervisor Dr. Dennis Higgs. Funding provided by NSERC.

Project Overview:

Stingrays possess multiple sensory and behavioural adaptations used for communication; however, little is known about their hearing when compared with teleosts (bony fish). It is hypothesized that stingrays use their ears and lateral line to orient themselves to biotic sounds, such as prey items, therefore noise present within their environment can interrupt or mask ecologically relevant sounds. While there is available data of noise influences on teleosts, there is a gap in our knowledge regarding noise impacts on sharks and stingrays. There are two major aims in the current study: first I aim to determine behavioural response of southern stingrays (Hypanus americanus) to both low frequency sound and boat noise and second, I aim to differentiate a response between domestic, tourist-fed stingrays and wild stingrays. I plan to use this marine species as a biomarker for other marine fish with similar hearing capabilities to assess the effects of boat noise in important nursery habitats.

Conservation Importance:

Stingrays are important predators that often face anthropogenic threats through habitat degradation and overfishing; furthermore, approximately 1.5 million tons of elasmobranchs (sharks, skates and rays) are killed annually as bycatch (Bonfil ,1994; Jacoby et al., 2012). There is little data regarding potential anthropogenic noise influences on elasmobranchs; here we aim to bridge the gap in our knowledge and determine the impacts of low-frequency and boat noise on the southern stingray. The first step to conserving a species is to determine baseline behavioural practices and identifying the different stressors present within their environment.


Evan Byrnes - Murdoch University (Perth, WA, Australia)

Project Overview:

Every animal requires a minimum amount of space to survive and thrive. The amount of space an animal regularly uses is called its home range. Body size is considered the principal determinant of animals’ home range size, due to its correlation with daily energetic needs; as animals get bigger they require more food and thus require more space to provide that food. While this idea is relatively straight forward, it has been difficult to confirm in the wild due to difficulties of measuring the metabolic rate of free-ranging animals. This is particularly pertinent for marine animals, like sharks, where we cannot continually monitor their behaviour and internal state. However, recent advancements in biologging technology, namely accelerometers provide a tool for estimating the metabolic rates of free-ranging sharks. Accelerometers are motion sensitive tags, and when attached to a shark, they record physical activity, which can be used to estimate energy expenditure, just like a FitBit.

This study set out to determine how body size dependent metabolic rate of lemon sharks (Negaprion brevirostris) govern their home range size and habitat use. Using acceleroameters, we will calculate how metabolic rate increases with body size, and by combining this knowledge with observations of individual movement, diet, and behaviours in the wild, aim to predict how size related energetics predict habitat use.

Research Questions:

  1. How does the metabolic rate of lemon sharks change as body mass and activity levels increase?

  2. Does home range size scale with metabolic rate, and how does the scaling relationship change across seasons and through ontogeny?

  3. How does lemon shark activity patterns and within home range behavioural habitat use change with body size, and what are the associated energetic trade-offs?

  4. How does competition and limited supply of energy resources (i.e. prey) constrain the relationship between home range size and metabolic rate?

Conservation Importance:

In a world where human activity and development continues to further encroach on wild areas, it is important to understand the minimum spatial and resource requirements of animals so that effective management practices can be established. For example, marine protected areas (MPAs) are often designed to protect animal species, amongst other things, from anthropogenic threats. However, the success of MPAs is largely reliant on animals remaining within the boundaries and having sufficient resources to grow and reproduce. As such, the mechanistic understanding of shark home range and energy requirements developed by this project will provide important information for ensuring effective MPA design.

Photo: Georgia Aquarium / Addison Hill

Research Questions

The overarching goal of the proposed work is to evaluate the role of diet in the microplastics load of tiger sharks. Focused sampling of tiger sharks will occur in both coastal and offshore locations and include all life history stages. Currently, we are sampling tiger sharks with colleagues in the US, Bahamas, Costa Rica, and Australia in order to take a global view of the impacts of microplastics. Our work in the Bahamas with the Bimini Biological Field Station is important as it provides us with access to all life history stages of tiger sharks, ranging from young pups to adults, to track the prevalence of microplastics with ontogenic shifts in feeding ecology. This project aims to:

  1. Understand diet and feeding ecology in tiger sharks using stable isotope, fatty acid, and DNA barcoding techniques

  2. Quantify circulating microplastics load and polymer type in the blood of tiger sharks

  3. Compare diet and microplastics load between life history stages and geographic locations, globally

Video: Georgia Aquarium 

Dr. Lisa Hoopes & Dr. Kady Lyons - Georgia Aquarium (Georgia, USA)

Project Overview:

Microplastics (<5mm in size) are ubiquitous within marine habitats1 and these synthetic particles originate from a variety of sources, including fragments of larger plastics by UV degradation or wave action and physical abrasion; waste water containing microbeads from cosmetics or microfibers from the washing of textiles; and spills or run-off of pre-production pellets (nurdles) or polystyrene beads*2-6.  By virtue of their small size, microplastics are consumed by a variety of taxa (zooplankton, marine invertebrates, fish, seabirds, marine mammals*7-10), either directly through accidental consumption*11, 8 or through active selection due to misidentification of microplastics for food*12-13. Microplastics may also be ingested indirectly through tropic transfer14. 

As a group, sharks are secondary and tertiary consumers and many species occupy upper trophic levels of marine food webs*19. Sharks can be important species in regulating the structure and function of marine ecosystems through predation, making it essential to understand both their feeding ecology and anthropogenic threats to survival. Ingestion of plastics, either directly or indirectly through trophic transfer, poses a significant risk to population levels of apex shark species. 

These negative impacts of plastics ingestion will likely differ within and between species based on foraging strategy, diet, and/or geographic range. For example, tiger sharks are considered generalist foragers and large prey become more important with ontogeny in this species20. Stomach contents of adult tiger sharks have revealed a variety of diet items including fish, crustaceans, sea snakes, sharks, rays, marine mammals, sea turtles, sea birds and even terrestrial prey. A number of inedible objects (license plates, tires, baseballs) have also been detected in their stomach contents, often attributed to their indiscriminate feeding style. Of the prey ingested by tiger sharks, seabird and sea turtles are species known to be heavily impacted by plastics ingestion21,22. The foraging strategy of tiger sharks combined with the high likelihood for trophic transfer of microplastics from their prey make this a compelling species to evaluate the impact of diet on microplastics load.

Conservation Importance

Microplastics ingestion can alter animal health through a reduction in feeding capacity, energy reserves, and reproductive output; decreased power and capacity for predation, endocrine disruption, alteration to intestinal function, and through increased oxidative stress and immune disfunction15-18. The negative effects of plastics ingestion underline the urgency to evaluate the impacts of plastics in marine food webs to end consumers.

1GESAMP, 2015. Sources, Fate and Effects of Microplastics in the Marine Environment: a Global Assessment, Reports and Studies. IMO/FAO/UNESCO-IOC/ UNIDO/WMO/IAEA/UN/UNEP/UNDP Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection. RG.2.1.3803.7925.

2Andrady, A.L., 2011. Microplastics in the marine environment. Mar. Pollut. Bull. 62, 1596e1605.

3Barnes, D.K.A., Galgani, F., Thompson, R.C., Barlaz, M., 2009. Accumulation and fragmentation of plastic debris in global environments. Philos. Trans. R. Soc. B 364, 1985e1998.

4Boucher, J., Friot, D., 2017. Primary Microplastics in the Oceans: A Global Evaluation of Sources. IUCN, Gland, Switzerland. IUCN.CH.2017.01.en.

5Browne, M.A., Crump, P., Niven, S.J., Teuten, E., Tonkin, A., Galloway, T., Thompson, R., 2011. Accumulation of microplastic on shorelines worldwide: sources and sinks. Environ. Sci. Technol. 45, 9175e9179. es201811s.

6Napper, I.E., Thompson, R.C., 2016. Release of synthetic microplastic plastic fibers from domestic washing machines: effects of fabric type and washing conditions. Mar. Pollut. Bull. 112, 39e45. j.marpolbul.2016.09.025

7Amelineau, F., Bonnet, D., Heitz, O., Mortreux, V., Harding, A.M.A., Karnovsky, N.,  Walkusz, W., Fort, J., Gremillet, D., 2016. Microplastic pollution in the Greenland  Sea: background levels and selective contamination of planktivorous diving seabirds. Environ. Pollut.

8Cole, M., Lindeque, P., Fileman, E., Halsband, C., Goodhead, R., Moger, J., Galloway, T.S., 2013. Microplastic ingestion by zooplankton. Environ. Sci. Technol. 47, 6646e6655.

9Lusher, A.L., McHugh, M., Thompson, R.C., 2013. Occurrence of microplastics in the gastrointestinal tract of pelagic and demersal fish from the English Channel. Mar. Pollut. Bull. 67, 94e99.

10Lusher, A.L., Hernandez-Milian, G., O'Brien, J., Berrow, S., O'Connor, I., Officer, R., 2015. Microplastic and macroplastic ingestion by a deep diving, oceanic cetacean: the True's beaked whale Mesoplodon mirus. Environ. Pollut. 199, 185e191. 

11Besseling, E., Foekema, E.M., Van Franeker, J.A., Leopold, M.F., Kühn, S., Bravo Rebolledo, E.L., Heße, E., Mielke, L., IJzer, J., Kamminga, P., Koelmans, A.A., 2015. Microplastic in a macro filter feeder: humpback whale Megaptera novaeangliae. Mar. Pollut. Bull. 95, 248e252.

12de Sa, L.C., Luís, L.G., Guilhermino, L., 2015. Effects of microplastics on juveniles of  the common goby (Pomatoschistus microps): confusion with prey, reduction of the predatory performance and efficiency, and possible influence of developmental conditions. Environ. Pollut. 196, 359e362. j.envpol.2014.10.026.

13Hall, N.M., Berry, K.L.E., Rintoul, L., Hoogenboom, M.O., 2015. Microplastic ingestion by scleractinian corals. Mar. Biol. 162, 725e732. 015-2619-7

14Nelms SE, Galloway TS, Godley BJ et al. 2018. Investigating microplastic trophic transfer in marine top predators. Environ Pollut 238:999-1007.

15Cole, M., Lindeque, P., Fileman, E., Halsband, C., Galloway, T.S., 2015. The impact of polystyrene microplastics on feeding, function and fecundity in the marine copepod Calanus helgolandicus. Environ. Sci. Technol. 49, 1130e1137. https://

16Peda, C., Caccamo, L., Fossi, M.C., Gai, F., Andaloro, F., Genovese, L., Perdichizzi, A., Romeo, T., Maricchiolo, G., 2016. Intestinal alterations in European sea bass Dicentrarchus labrax (Linnaeus, 1758) exposed to microplastics: preliminary results. Environ. Pollut. 212, 251e256. j.envpol.2016.01.083.

17Sussarellu, R., Suquet, M., Thomas, Y., Lambert, C., Fabioux, C., Pernet, M.E.J., Le Goïc, N., Quillien, V., Mingant, C., Epelboin, Y., Corporeau, C., Guyomarch, J., Robbens, J., Paul-Pont, I., Soudant, P., Huvet, A., 2016. Oyster reproduction is affected by exposure to polystyrene microplastics. Proc. Natl. Acad. Sci. https://, 201519019

18Wright, S.L., Rowe, D., Thompson, R.C., Galloway, T.S., 2013a. Microplastic ingestion decreases energy reserves in marine worms. Curr. Biol. 23, R1031eR1033.

19Cortés, E., 1999. Standardized diet compositions and trophic levels of sharks. ICES Journal of Marine Science, 56: 707–717.

20Lowe CG, Wetherbee BM, Crow GL and Tester AL. 1996. Ontogenic dietary shifts and feeding behavior of the tiger shark, Galeocerdo cuvier, in Hawaiian waters. Environ Biol Fish, 47:203-211.

21Wilcoxa C, Van Sebillebc E, Hardesty BD. 2015. Threat of plastic pollution to seabirds is global, pervasive, and increasing. PNAS 22Duncan EM, Broderick AC, Fuller WJ et al. 2018. Microplastic ingestion ubiquitous in marine turtles. Global Climate Change 2018:1-9.

The embryology and reproductive cycles have been published as: Holland, N. D. and Holland, L. Z. 2010. Laboratory spawning and development of the Bahama lancelet, Asymmetron lucayanum (Cephalochordata): fertilization through feeding larvae. Biological Bulletin 219: 132-141. Holland, N. D. 2011. Spawning periodicity of the lancelet, Asymmetron lucayanum (Cephalochordata) in Bimini, Bahamas. Italian Journal of Zoology 78: 487-486.

If interested in some details, some of our papers are: Yue, J. X. et al. 2014. The transcriptome of an amphioxus, Asymmetron lucayanum. from the Bahamas: a widow into chordate evolution. Genome Biology and Evolution 6: 2681-2696; Yue, J. X.  et al. 2016. The evolution of genes encoding for green fluorescent proteins: insights from cephalochordates (amphioxus). Scientific Reports 6: article 28350; Yue, J. X. 2017. Conserved noncoding elements in the most distant genera of cephalochordates: the Goldilocks principle. Genome Biology and Evolution 8: 2387-2405. Most recently, we have been taking advantage of the relatively small body size of Asymmetron to work out the details of its neuroanatomy: Holland N. D. and Somorjai, I. M. L. 2020. The sensory peripheral nervous system in the tail of a cephalochordate studied by serial blockface scanning electron microscopy (SBSEM). Journal of Comparative Neurology DOI 10.1002/cne 24913. This work and more like it is a preliminary to study Asymmetron tail regeneration (a subject that Andrews studied crudely in 1893) with modern techniques.

Dr. Nicholas Holland - Distinguished Professor at University of California at San Diego

Project Overview:

For my work in evolutionary development (EvoDevo), I needed embryos and larvae for studying timing and location of the genes that direct development. Nobody had any idea about reproductive biology of Asymmetron, so I just started making quick trips from California to Bimini every few weeks for a couple of years. By sheer good luck, I finally found out that the animals spawn on the day before the new moon (in the lab, you can fool them into doing that with an artificial moonlight cycle).


We can keep the adults healthy and breeding for about two years in the laboratory on diets of cultured algae, but the animals die of old age. We can start embryo cultures too, but they only survive as far as early larvae (so there is probably some food normally present in the Bimini water that we do not yet know about – solving that problem is another interesting project to pursue). Our specific projects involving Asymmetron have included hybridizing them with another cephalochordate genus (separate since the time of the dinosaurs) that show the offspring have some characters that split the difference between the parents (Holland, N. D. et al. 2015. Hybrids between the Florida amphioxus (Branchiostoma floridae) and the Bahamas lancelet (Asymmetron lucayanum: developmental morphology and chromosome counts. Biological Bulletin 228: 13-24).


We have also been able to make some interesting detailed comparisons between the genomes of Asymmetron versus cephalochordates in the genus Branchiostoma. Gene sequences can change so much in distantly related animals that they cannot be reliably compared in detail. The favorable thing for our comparisons is that homologous genes in the two genera have changed enough to be interesting but not enough to be unrecognizable (in one of the publications cited below, we christened this “the Goldilocks principle”).


In sum, Asymmetron lucayanum is important due to its key position in the tree of life and Bimini is the most convenient place in the world to obtain this species.  

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