 Euryhaline elasmobranchs are sharks and rays that utilise
estuarine environments.
Ecological Niche
Describe abiotic and biotic variables that affect an organism and how
that organism then affects those sa...
Fundamental and Realized Niches
2 ways the niche is described

Fundamental

Why are penguins
absent?
Niche Width

Realized
Significance of Elasmobranchs
Ecologically
 Apex & meso predators - extensive role in
ecosystems
(McDavitt, 1996)
Based o...
Importance of Predators
 ‘Top down’ effect in food webs
 Reductions - serious ramifications for ecosystems (Estes et
al....
Elasmobranchs (sharks and rays) –
Predators at risk.
Indo- Australian at Risk

North Central American
Species at Risk
Conc...
Trophic Niche - Diet
•

Assists in determining
effect of species loss

•

Bearhop et al. (2004) conceptual framework
• 3 b...
Spatial Niche – Space Usage
• Is influenced by:
• species dispersal
• conducive environmental
conditions & resources for
s...
Indigenous Communities & Euryhaline
Elasmobranchs
 85% of coastal and estuarine environments
Norma Joshua in Normand 2004...
http://cheekydancers
.wordpress.
Com/original-dance-history/

Indigenous Ecological
Knowledge (IEK)

http://jobs.nsw.gov.a...
Examples of IEK
Cyclic patterns
Caribou,
Canada
(Ferguson, Williamson &
Messier 1998),

Medicinal
plants in Mexico
(Yucatá...
“Two way” learning
• Indigenous & non-Indigenous
people share knowledge
• Contribute historical &
observational data (Ens,...
‘Two Way Tool Box’
How important is the
freshwater
environment in the
ecology of euryhaline
elasmobranchs ?

IEK
Interview...
Euryhaline Elasmobranchs
 Tolerate a range of salinities

 Highly specialised life histories

 Global decline due to:
...
Why study spatial & trophic ecology in
NT?
 Legal fisheries 10 cause of sawfish decline
 NT riverine environment “near p...
NT Rivers
 Massive tidal ranges, increasing salinity (dry season) &
extensive mangrove forests
 Remote & difficult to ac...
Trophic niche of euryhaline
elasmobranchs
 Diet from X- rays & gut content analysis
Detrital
matter
G. garricki

Other

P...
Spatial niche of euryhaline
elasmobranchs.
 Movement & Distribution Studies
 Distribution: - rivers, estuaries & coastal...
IEK knowledge of Elasmobranchs in
NT
 Limited IEK on shark & ray species – particularly
in NT
 Sea country people have d...
Aims
1. To determine the inter- and intra-specific trophic
niches of euryhaline elasmobranchs in NT tropical
aquatic ecosy...
To determine the inter- and intra-specific trophic niches of
euryhaline elasmobranchs in NT tropical aquatic ecosystems.
N...
Trophic Methods
Fatty acid (FA) & stable isotope (SIA) analysis
 Fish caught using: Hook and line (barbs
removed), gill n...
Stable Isotope Analyses

https://www.niwa.co.nz/publications/wa/vol12-no1-march-2004/shortfin-eels-in-tewaihora

Nitrogen ...
Lipid Analysis
Marine algae
synthesize lipids
Vertebrates ingest lipids
from food chain

Cell membranes & adipose tissue
s...
Trophic Analysis – Mixing Models
 Determine proportions of food to reconstruct diet
 Inclusion of fatty acids refines mo...
To determine the spatial niche (i.e. movement and habitat
use) of a model euryhaline elasmobranch species (the bull
shark,...
Defining spatial niche using
acoustic tagging
• 30 C. leucas –tagged with
acoustic transmitter in
abdominal cavity
• “ping...
South Alligator
River
Location of acoustic
receivers
= Acoustic Receiver

Arnhem Highway

Yellow Waters

Map from Richard ...
Analysis of Spatial Data
 Range testing acoustic receivers

 Extent & timing of movement
 Analyse correlations between ...
To record indigenous knowledge & the ecological & cultural role
of euryhaline elasmobranch species.
On preliminary visit people were willing to share
knowledge of sightings of Sawfish and potential
habitat.
Study
Background
of
community

Implement
tools in
communal
areas

Reflect & adjust
tools on
recommendations

IEK Methods –...
Semi-Structured
Interviews

 Open questions - encourage discussion &
range of topics

 Interviews ‘on country’ (if possi...
Yugul Mangi Land & Sea Rangers as
research assistants
• Potentially collect samples from
community
• Safety on country (e....
Timeline

Presentations
• Poster OCS/ASFB conference - July 2012
• Talk People in Land & Sea conference September - 2012
•...
Significant Partners & Ethics
 NAMRA scholarship $15 000
operation costs / year
 NERP Marine Biodiversity Hub
(CDU, NT F...
Acknowledgements
Thankyou to everyone who has provided advice, assistance &
support!
 NAMRA
 Supervisors
 NERP – Peter ...
PhD confirmation - ecology of estuarine sharks & rays
PhD confirmation - ecology of estuarine sharks & rays
PhD confirmation - ecology of estuarine sharks & rays
PhD confirmation - ecology of estuarine sharks & rays
PhD confirmation - ecology of estuarine sharks & rays
PhD confirmation - ecology of estuarine sharks & rays
PhD confirmation - ecology of estuarine sharks & rays
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PhD confirmation - ecology of estuarine sharks & rays

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This is a ppt that was used in my confirmation for candidature. It describes how I will use stable isotope and fatty acid analysis to determine what estuarine sharks and rays eat and which areas of the South Alligator River, (NT, Aus) they utilise. This will then inform environmental managers of which areas are critical to the survival of these species.

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  • The ocean is included in the fundamental etc just cant see here~Facilitation both species benefiting from the interaction
  • Yongulu - sleeping speared by another clan memember and then chased the person up river creating the land scape – don’t annoy a shark clan member!! Sawfish Considered supernatural beings – creating natural and social order in many countries PNG –spirit controls the fecundity of fish, if killed – destructive storms (McDavitt, 1996)Groote Eyelandt –cut through central hill to Angurrkwurrikba Salt Lake followed by stingrays (all of which, including the waters are totems) (Waddy, 1982) Whaler Sharks Yongulu believe that the ancestral whale shark carved the river and landscape whilst enragedshark-based ecotourism contributed an estimated .30% towards the Maldives GDP (Ndurya & Kihara, 2009). $3,300 per year, and over $35,000 per year at the most popular dive sites. Grey reef sharkUS$800 million to the Bahamian economy (Cline, 2008). Sesasonal cues
  • http://www.pacificvoyagers.com/voyaging-societies/uto-ni-yalo/environmental-concerns-5/
  • Dietary differences in individuals may occur due to ontogenetic or gender differences, or availability of food in their habitat
  • Organisms movement results in change of physical space affecting assemblages, distribution & interspecific competition .Species can share or be aggressive – at an inter or intraspecific Species requirements for space can be specific such as “habitat specialists” that require specific environmental conditions compared to “habitat generalists” that can tolerate a range of conditions . Habitat specialists are generally less abundant and may have a greater extinction risk due to disturbance. This has been evident in fish e.g. , arthropods e.g. and primates e.g. . A mobile species may require several habitat sites that they move between to find; mates, breeding habitats, avoid predators and find prey. In doing so they influence community dynamics
  • usage of both the river and sea particularly significant, Act of fishing allows for the transmission of knowledge to the next generation
  • Increasingly, around the world the use of multiple knowledge systems have been advocated in management planning and the understanding of species and ecosystems Some Indigenous Australians have an accumulated knowledge of species based on oral histories and information transferred through past generations (sometimes referred to as Traditional or Indigenous Ecological Knowledge). Indigenous Ecological Knowledge (IEK) refers to the interconnected science and cultural knowledge systems that Indigenous people have acquired through millennia of observation, experimentation and teaching that has led to an accumulated body of knowledge .
  • Abundance and distribution - medicinal plants in Mexico Cyclic patterns – Caribou in Canada Habitat preferences – fish in Puerto Rico Dietary requirements of a range of species.Fire management techniques Dugongs and turtles , and the co-management of the Great Barrier Reef .
  • Research with theAnangu (Indigenous people of central Australia)
  • E.g. Smalltooth Sawfish, Pristis pectinata USA (Simpfendorfer, Wiley & Yeiser 2010), Freshwater Sawfish Pristis pristis in Guinea (Robillard & Séret 2006), Africa and South East Asia (Compagno 2002; Siriraksophon 2012)
  • illegal foreign fishing, particularly in Gulf of Carpentaria so that trophic levels and feeding specializations can be determined.
  • Comparatively compared to AustraliaAs such the river ecosystems of the NT are ideal to investigate euryhaline elasmobranchs
  • Numbers low , 3 ,5 & 10
  • (excepting McDavitt) Totem a representation or related to a natural object
  • Sampling integratedLive V muscle can give indication of change or variation in dietThe muscle will be collected in the caudal peduncle region
  • Useful as tracers as organmiscans can modify and lengthen but this is limited as it goes up the food chainLipids are generally taken up in their basic formFat storedMarine algae are essesntially the only organism capaple of producing Long Chain Polyunsturated FA
  • where δ15Nbaseline organism and TPbaseline organism are the δ15N value and predicted TP for a low trophic level or baseline organism in the ecosystem, normally a sessile organ- ism such as a clam or mussel and 􏰶15N is the DTDF (Post, 2002 Diet discrimination factors
  • Site attachment or driven by enviromental variables
  • Gate – time, date unique code120 sec nominal delay Bewary of false codes – one detection probably not right
  • noise to avoid interferenceRange test – hang transmitter off boat in approbriate location of where the fish would swim & left in place to test the number of transmissions
  • Consultation process is Iterative based on continuous feedback from community
  • Informed prior consent
  • These relationships are fundamental to any undertaking in Indigenous communities .
  • PhD confirmation - ecology of estuarine sharks & rays

    1. 1.  Euryhaline elasmobranchs are sharks and rays that utilise estuarine environments.
    2. 2. Ecological Niche Describe abiotic and biotic variables that affect an organism and how that organism then affects those same variables (Chase & Leibold 2003; Hirzel & Le Lay 2008; Hutchinson 1957; McInerny & Etienne 2012). O H N C N Habitat
    3. 3. Fundamental and Realized Niches 2 ways the niche is described Fundamental Why are penguins absent? Niche Width Realized
    4. 4. Significance of Elasmobranchs Ecologically  Apex & meso predators - extensive role in ecosystems (McDavitt, 1996) Based on Pen Ts’ao Kang Mu (pharmacopeia) Culturally  Many coastal societies have stories /legends  E.g. PNG, Australia – Yolngu & Angurugu, Africa, China, Borneo, even Europe/UK Economically Artist: Nekingaba Maminyamanja, Date: c. 1980. McDavitt (2005)  Fishing, curios, tourism, herbal medicine, food Li Livres dou Tresor codex, facsimile di M. Moleiro: fol. 45v
    5. 5. Importance of Predators  ‘Top down’ effect in food webs  Reductions - serious ramifications for ecosystems (Estes et al. 2011)  E.g. Chesapeake Bay, USA scallop industry decimated (Myers et al. 2007) Apex predators (Makos, Hammerheads Whalers) eat rays Over fishing + habitat degradation Meso predator – Cownose Ray eats Oysters Population explosion Oyster bed healthy Decimated bivalves
    6. 6. Elasmobranchs (sharks and rays) – Predators at risk. Indo- Australian at Risk North Central American Species at Risk Concern 14% 60% not at risk Concern 40% 86% not at risk Why at Risk?  Anthropogenic influences e.g. fishing & habitat destruction (Cavanagh et al. 2003; Myers et al. 2007) (Baum & Worm 2009; Dulvy et al. 2008; Kyne et al. 2012; Myers et al. 2007; White & Kyne 2010). Why Important? • Key roles in marine ecosystems & communities • Influence species diversity, population sizes & prey (Cortés 1999; Heithaus et al. 2008)
    7. 7. Trophic Niche - Diet • Assists in determining effect of species loss • Bearhop et al. (2004) conceptual framework • 3 broad types of consumers: • “Specialists” - narrow range of prey • “Generalists” • Type A - wide range of prey • Type B generalists – individuals eat specific prey from wide range of items Figure 1: Representation of the differences between feeding types in consumer populations. (Bearhop et al. 2004)
    8. 8. Spatial Niche – Space Usage • Is influenced by: • species dispersal • conducive environmental conditions & resources for survival • reproduction • interspecific interactions (predators, pathogens) • Habitat specialists - more at risk (Arakaki & Tokeshi 2010; Hirzel & Le Lay 2008; Soberón 2007; Pulliam 2002)
    9. 9. Indigenous Communities & Euryhaline Elasmobranchs  85% of coastal and estuarine environments Norma Joshua in Normand 2004  Knowledge of NT ecosystems extensive & historic  Are culturally (totemic) & economically significant  Australia’s indigenous harvest – preliminary estimates only  Extent, impacts & data lacking. (Ens 2012; Altman, Buchanan & Larsen 2007; McDavitt 1996, 2005; Waddy 1988; Heath 1980, 1988)
    10. 10. http://cheekydancers .wordpress. Com/original-dance-history/ Indigenous Ecological Knowledge (IEK) http://jobs.nsw.gov.au/  Accumulated knowledge of species based on oral histories & information transferred through past generations (TEK or IEK)  Interconnected science and cultural knowledge systems  Observations from 1000’s of years of living in an environment can be applied to western niche concept – particularly spatial niche (Berkes 2008; Horstmann & Wightmann 2001) http://glucoensuremd.com/2/aboriginal-men-hunting http://www.janesoceania.com/australian_aboriginal_anthropology/index1.htm
    11. 11. Examples of IEK Cyclic patterns Caribou, Canada (Ferguson, Williamson & Messier 1998), Medicinal plants in Mexico (Yucatán) (Hunn 2001; Nabhan 2001) Fire management techniques (Russell- Habitat preferences, Puerto Rico (García-Quijano 2007) Smith, Whitehead & Cooke 2009 Co-management – Great Barrier Reef (George, Innes & Ross 2004; Nursey-Bray 2009)
    12. 12. “Two way” learning • Indigenous & non-Indigenous people share knowledge • Contribute historical & observational data (Ens, 2012) Australian studies using this method:  The habitat, diet & behaviour of Rock-Wallabies (Telfer & Garde 2006)  Reptile behaviour, movement & distribution (Baker 1992)
    13. 13. ‘Two Way Tool Box’ How important is the freshwater environment in the ecology of euryhaline elasmobranchs ? IEK Interviews Cultural Mapping Understanding: Trophic Niche & Spatial Niche Stable Isotope Analysis Acoustic Tagging Lipid Analysis
    14. 14. Euryhaline Elasmobranchs  Tolerate a range of salinities  Highly specialised life histories  Global decline due to:  Rapid human population growth  Disturbance (Compagno 2002; Compagno & Cook 1995)  Rare, threatened & ‘data-poor’ Smalltooth Sawfish, Pristis pectinata USA
    15. 15. Why study spatial & trophic ecology in NT?  Legal fisheries 10 cause of sawfish decline  NT riverine environment “near pristine”  Critical habitats / key prey species  Accurate management plans Bull Shark Carcharhinus leucas Speartooth Shark  Range of species Glyphis glyphis Freshwater Sawfish Pristis pristis Northern River Shark Glyphis garricki Dwarf Sawfish Pristis clavata Freshwater Whipray Himantura dalyensis
    16. 16. NT Rivers  Massive tidal ranges, increasing salinity (dry season) & extensive mangrove forests  Remote & difficult to access  “ Near Pristine” (more data needed on impacts)  Feral animals, weeds, development, agriculture & mining  International strongholds for aquatic biodiversity
    17. 17. Trophic niche of euryhaline elasmobranchs  Diet from X- rays & gut content analysis Detrital matter G. garricki Other P. pristis P. pristis G. garricki P. pristis P. clavata C. leucas C. leucas C. leucas C. leucas C. leucas • From Stable Isotope Analysis: • Pilot study: dietary & habitat overlap within sawfish P. pristis and P. clavata different from A. cuspidata. • USA C. leucas: Evidence of Type B generalists with individual specialization
    18. 18. Spatial niche of euryhaline elasmobranchs.  Movement & Distribution Studies  Distribution: - rivers, estuaries & coastal areas of northern Australia  P. pristis - WA acoustic tagging, conventional tags, some genetic work  C. leucas - genetic studies , habitat partitioning & directly from acoustic tagging in South QLD & USA  Tillet (2011) dissertation NT  Only C. leucas study in ‘near pristine’ river systems (Peverell 2005; Pillans et al. 2009; Stobutzki et al. 2002; Thorburn et al. 2008; Thorburn et al. 2003; Thorburn & Rowland 2008; Whitty et al. 2009).
    19. 19. IEK knowledge of Elasmobranchs in NT  Limited IEK on shark & ray species – particularly in NT  Sea country people have deep totemic connections (e.g. Ngukurr, Groote) – more knowledge exists?  Intact cultural landscapes of the NT  Potentially inform management of river & estuaries (McDavitt 1996, 2005; Waddy 1988)
    20. 20. Aims 1. To determine the inter- and intra-specific trophic niches of euryhaline elasmobranchs in NT tropical aquatic ecosystems. 2. To determine the spatial niche (i.e. movement and habitat use) of a model euryhaline elasmobranch species (the bull shark, C. leucas). 3. To record indigenous knowledge & the ecological & cultural role of euryhaline elasmobranch species.
    21. 21. To determine the inter- and intra-specific trophic niches of euryhaline elasmobranchs in NT tropical aquatic ecosystems. Null Hypotheses: i. ii. Different species (e.g. P. pristis, C. leucas, G. glyphis and G. garricki) will be dietary specialists and have distinct partitions from each other. There will be no intra-specific dietary specialization within species.
    22. 22. Trophic Methods Fatty acid (FA) & stable isotope (SIA) analysis  Fish caught using: Hook and line (barbs removed), gill nets 4 -7 inch, demersal (bottomset) 20 hooks & Cast nets  Primary producers & invertebrates also sampled  Muscle tissue - longer turn over (more effective for diet) & if any unforseen mortalities - liver tissue  20 -30 individuals  Potential prey collected for SIA & fatty acids – 5 representatives Caudal Peduncle – site of biopsy
    23. 23. Stable Isotope Analyses https://www.niwa.co.nz/publications/wa/vol12-no1-march-2004/shortfin-eels-in-tewaihora Nitrogen fractionates & becomes enriched up the food chain (Post 2002) Trophic niche of species can be determined by comparing prey spp’s (Hussey et al. 2012).
    24. 24. Lipid Analysis Marine algae synthesize lipids Vertebrates ingest lipids from food chain Cell membranes & adipose tissue significantly influenced by consumption (Sargent, Tocher & Bell 2002).
    25. 25. Trophic Analysis – Mixing Models  Determine proportions of food to reconstruct diet  Inclusion of fatty acids refines model  Important to exclude confounding influences – urea, lipids  Trophic position estimate formula  TP elasmobranch = (δ15N elasmobranch − δ15N baseline organism)(δ15N)−1 + TP baseline organism
    26. 26. To determine the spatial niche (i.e. movement and habitat use) of a model euryhaline elasmobranch species (the bull shark, C. leucas) Null Hypothesis: C. leucas will be a habitat generalist and will not display habitat specialization.
    27. 27. Defining spatial niche using acoustic tagging • 30 C. leucas –tagged with acoustic transmitter in abdominal cavity • “ping” is received by an acoustic receiver • 33 acoustic receivers (NERP) South Alligator River • physical parameters
    28. 28. South Alligator River Location of acoustic receivers = Acoustic Receiver Arnhem Highway Yellow Waters Map from Richard Pillans - CSIRO
    29. 29. Analysis of Spatial Data  Range testing acoustic receivers  Extent & timing of movement  Analyse correlations between movement & habitat type, salinity, seasons, lunar cycles, tides  Find habitat preference & possible influences to that preference
    30. 30. To record indigenous knowledge & the ecological & cultural role of euryhaline elasmobranch species.
    31. 31. On preliminary visit people were willing to share knowledge of sightings of Sawfish and potential habitat.
    32. 32. Study Background of community Implement tools in communal areas Reflect & adjust tools on recommendations IEK Methods – Participatory Action Analyse data Research (PAR) determine whom Determine stakeholders, format plan, request permissions Input from elders, Yugul Mangi Rangers & community to interview further Format semi – structured questions Develop brief survey tool consisting of timelines and maps Write up including report for community Analyse data / draft Carry out interviews (Chevalier & Buckles, 2012; Baum, MacDougall, Smith 2006)
    33. 33. Semi-Structured Interviews  Open questions - encourage discussion & range of topics  Interviews ‘on country’ (if possible), approx. 1 hour, with refreshments  Interviewees dependant on number of knowledge holders  Electronically recorded  Ngukurr Language Centre  Payment offered to interviewees (Grenier 1998; Huntington 2000; Weiss, Hamann & Marsh 2012)
    34. 34. Yugul Mangi Land & Sea Rangers as research assistants • Potentially collect samples from community • Safety on country (e.g. river and road hazards) • Help identify key people with cultural rights to share knowledge • Relationship building within community
    35. 35. Timeline Presentations • Poster OCS/ASFB conference - July 2012 • Talk People in Land & Sea conference September - 2012 • Poster ESA conference- December 2012
    36. 36. Significant Partners & Ethics  NAMRA scholarship $15 000 operation costs / year  NERP Marine Biodiversity Hub (CDU, NT Fisheries) will contribute: field support, transport, tissue collection and the use of acoustic receivers.  Co- authorship offered to significant contributors ie The Yugul Mangi Land and Sea Rangers publication they will be listed as co-authors.  Stable isotope analysis Australian Institute of Marine Science (AIMS) at the Arafura Timor Research Facility (ATRF)  Fatty Acids will be analyzed with assistance from Dr. Peter Nichols of CSIRO Hobart.  NLC research permit: In Progress  S17 NT fisheries approved: S17/3268  Animal ethics approved: A12016  Human ethics approved: H12117
    37. 37. Acknowledgements Thankyou to everyone who has provided advice, assistance & support!  NAMRA  Supervisors  NERP – Peter Kyne Collection of samples & acoustic study  ATRF / AIMS  CSIRO – Peter Nichols  NT Fisheries (Grant Johnson)  Yugul Mangi Rangers  Ngukurr Community  Robertson Family - Ngukurr

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