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  • 1. The  movement  of  white  grunts   (Haemulon  plumierii)  rela5ve  to  habitat  and  boundaries  at  various   spa5al  and  temporal  scales   Stephanie  J.  Williams   Department  of  Marine  Sciences   University  of  Puerto  Rico,  Mayagüez  Campus  
  • 2. Outline:   Introduc5on:  Fish  Movement  vs.  Habitat  Boundaries   Objec5ves     Acous5c  Monitoring               Methods,  Results,  Discussion     Visual  surveys  /  Video  recordings               Methods,  Results,  Discussion   Applica5on  of  Acous5c  telemetry  with  Viewshed®           Methods,  Results,  Discussion   Overall  Conclusions   Acknowledgements  
  • 3. Introduc5on:     Why  study  fish  and  habitat?  FISH  DISTRUBTION,     HABITAT  DISTRUBTION,     ABUNDANCE,   ABUNDANCE,   MOVEMENT   ARRANGEMENT   ECOSYSTEM-­‐BASED     MANAGEMENT   DEFINE  NURSERY  AREAS,  EFH  &  TROPHIC  FLOWS   DESIGN  PRINCIPLES  FOR  MPAS  &     MARINE  SPATIAL  PLANNING   (Botsford et al. 2003, Barnes and Thomas 2005, Dahlgren et al. 2006)
  • 4. Theore5cal  Framework:     Habitat  Arrangement  &  Boundaries Open Sand Seagrass Gorgonians Coral Reef Affect  Probability,  Direc5on  &  Timing  of  Movement   (Appeldoorn et al. 2009) _____________________________________________________ Weins  (1992):  Percep5on  of  Boundary  Permeability:   1.  Contrast:  Differences  in  Benthic  Topography  Forma5ons      -­‐  deter  movement  (high);  allow  movement  (low)      -­‐  presence  of  predators  enhances  contrast  (ontogene5c  mig.  at                              larger  body  size;  reduce  probability  of  preda5on)  (Werner & Gilliam 1984)  2.  Thickness:    Distance  to  Cross  for  Next  Suitable  Habitat        -­‐  ability  to  detect  suitable  habitat  at  a  distance;  prior                                  experience  and  naviga5onal  skills  (Bardach 1958)
  • 5. Why  grunts?     Well-documented   Commercially & Ecologically Important (transfer nutrients) ( Appeldoorn & Lindeman 1985, Meyer & Schultz 1985, Clark et al. 2005) -­‐  Rest  During  Day  on  Coral  Reefs   -­‐  Forage  in  Seagrass  Beds  &  Sand  Flats   -­‐  Res5ng  Schools   -­‐  Solitary   -­‐  Dawn  re-­‐aggrega5on   -­‐  Dusk  Migra5on   _________________________________________________ Predictable Time, Predictable Route -  Navigation: Vision, Map-Sense, Compass Headings -  Degree & Timing: Size-Dependent -  Partition Feeding Area Efficiently/Reduce Predation Risk?(McFarland et al. 1979, Ogden & Quinn 1989, Bouwmeester 2005, Pittman et al. 2007)
  • 6. Grunts:  Movement  vs.  Habitat  WHAT  WE  CAN  EXPECT:  -­‐  Good  naviga5onal  skills  &  broad  knowledge  of  seascape  -­‐   Reef-­‐seagrass  (low)  vs.  Reef-­‐open  sand  (high  &  thick)       (Tulevech & Recksiek 1994, Appeldoorn et al. 2009)-­‐  Reef-­‐sand  interface  high  un5l  night  (low)     (Helfman et al. 1982, Rooker & Dennis 1991)  -­‐   Boundary  Permeability  Dependent  on:    -­‐  Lifestage    -­‐  Time-­‐of-­‐Day     -­‐  Loca5on    -­‐  Visibility      -­‐  Preda5on    -­‐  Presence  of  Con-­‐Specific/  Similar-­‐Sized  Inter-­‐Specific  Fish  WHAT  IS  MISSING:  -­‐  Extensive  long-­‐term  research  linking  transi5onal  lifestages  -­‐   Understanding  behaviors  at  boundaries,  movements  across            boundaries  and  limits  at  various  spa5al  and  temporal  scales  -­‐   Understanding  limita5ons  of  techniques  for  accurate              assessment  and  mapping  
  • 7. N Puerto Rico Objec5ves   Majimo Ridge Caracoles Corral Romero Turrumote-­‐  Inves5gate  movements  of  subadult  and  adult  white  grunts  at  various  scales   (Habitat,  Boundaries)   Image source: PR (bergoiata.org); La Parguera (IKONOS 2006)
  • 8. Objec5ves  Acous5c  Telemetry:      Test  boundary  responses  through  displacement    Iden5fy  short-­‐  and  long-­‐term  movement  paeerns  Visual  Surveys/Video  Recording:    Examine  distribu5on,  distances  moved,  an5-­‐predator   behaviors  and  rela5on  to  habitat  boundaries  at  Dawn,   Midday  and  Dusk  Acous5c  Telemetry  vs.  Viewshed®:    Examine  spa5al  paeerns  of  recep5on  range  rela5ve  to   geomorphology    vs.  line-­‐of-­‐sight  theory    
  • 9. Acous5c  Monitoring:  Study  Sites   EXPERIMENTAL DESIGN Displacement studies  -­‐  Use  Homing  to  test            Boundary  Response   Short-term movements                -­‐  Determine  Home  Range    Long-term movements  -­‐  ID  shi9s  in  home  range                      w/  longer  con=nuous  gaps   -­‐   19  Passive  acous5c  receivers   -­‐   76  Receiver  Loca5ons:    -­‐  Reef  crest    -­‐  Mid-­‐slope    -­‐  Reef-­‐sand  Interface        -­‐  Open  Sand   -­‐  21  Trap  Loca5ons  Source: CCMA/ Biogeography Team(http://ccma.nos.noaa.gov/products/biogeography/lidar_pr)
  • 10. Acous5c  Monitoring:  Equipment   -­‐   Transmieer:  V7  (7x20mm,  0.75g  in  SW;  69kHz)        Configura5ons  of  36  tagged  fish:            1.  7  fish  -­‐    Base  life:  52  days              2.  10  fish  -­‐  Base  life:  100  days          3.  19  fish  -­‐  Base  life:  220  days  -­‐   VR2  &  VR2W  Receivers:      -­‐  Records  Transmieer  ID  Code,  Time  &  Date    -­‐  Nominal  range:  ~250m  radius  -­‐   Boat-­‐based  VH-­‐110  Direc5onal  Hydrophone      -­‐  Records  ID  code  on  VR60  PC  Solware  -­‐  VUE  Solware:  12  Uploads  (08/16/08  –  11/20/09)  
  • 11. Tagging  Methodology  
  • 12. Data  Analysis  -­‐  Time-­‐series  results  organized  into:    1.    Maps  to  show  spa5al  scale  of  movement    2.  Graphs  to  summarize  temporal  paeerns     _____________________________________________________-­‐  Correla5ons  within  &  among  days  to  ID  trends    at  various  scales  &  presence/absence  paeerns    (Autocorrela5on  Func5on/Periodograms(Enright  1965,  Box  &  Jenkins  1970))   _____________________________________________________-­‐  Habitat  zone  u5liza5on  assessed  to  ID  spa5al  trends    (Forereef,  Backreef,  Forereef-­‐Backreef  Transi5on,  Channel)    
  • 13. Results:  Fish  Displacements  -­‐   5  adults  -   distance  between  reefs    w/  open  sand  &  w/  reef/gorg.  (200m-­‐730m)      -­‐   No  white  grunts  at  release  sites  -­‐   Boat-­‐Based  Hydrophone:  homeward-­‐  bound  direc5on  -­‐   Mo5va5on  to  return  by  day  -­‐  Fish  50350  only  successful  return:  to  WBT  by  night  (109  days)  
  • 14. -  7: 4 adults, 3 subadults Results:  Fish  Displacements  -  Greater Challenges:1. Increasing Distance 870m-2.8km2. More areas w/ other white grunts3. Only from WBT4. Replicates-  Records: 7- 54 days- All adults returned/ after days by night-  Subadults: no return- left release site after ~1wk
  • 15. Results:  Short-­‐term  Movements   Max. Dist.: ~360m Max. Dist.: ~225m-  14 adults(50350, 60609,14)-  W. ends of Turrumote (n=6) & Corral (n=5) & E. Forereef Corral (n=3) E. Forereef Corral-  Records: 12/200-215/218 days Max. Dist.: (Short time intervals ~100m of presence/absence)
  • 16. Short-­‐term  Results:  Turrumote  5034550350 -  Predominant use of backreef at night & forereef during day -  Changing patterns of several weeks for use of backreef diurnally - Individual variability - Faster to Forereef: ~30min - Slower Return: ~1hr
  • 17. Short-­‐term  Results:  W.  Corral   -  All-day use of transition on slope/ weekly p/a - Shift: decreasing to increasing at backreef all day50364 -  Nocturnal use on slope - Shift: decreasing to increasing at backreef all day; 50368 shallow backreef at night only
  • 18. Short-­‐term  Results:  E.  Corral  -  All-day use of reef- sand interface w/ minimal to no detections between dusk & dawn ________________________________________________ Turrumote  &  Corral:     -  Shifting movements and activity at multiple receivers (relocation of receivers) -  All movements occurred on small portion of available reef (up to ~300m in range) -  Twilight Movement: Facilitate Presence/Absence Patterns & Frequency of Detections
  • 19. Results:  Long-­‐term  Movements  -  3 adults-  Caracoles Forereef (n=2) and Májimo Ridge (n=1)-  No large-scale, offshore, reef-boundary-crossingto other emergent reefs occurred-  Records: 16/230 – 117/231 days-  Longer temporal shift in specific locations on reefcrest and forereef-sand interface-  Geomorphology similar at both locations(Reef crest: 3-5m; Reef-sand: 8-12m)- Connectivity - large patch reefs off emergent reefstructure- potentially more permeable than Turr/Corr-  Scattered presence of white grunts at both just as E. Forereef Corral Max. Dist.: ~150m
  • 20. Results:  Long-­‐term  Movements   -  Greater variations in absence at a single receiver -  Detecting fish in new/nearby locationsCaracoles -  Shifts in habitat use at varying degrees over time 50354 -  3-month intervals -  Relocation 50361 once receiver moved______________________________________________________________________Májimo Ridge 50359 -  Monthly intervals -  Relocation once receiver moved
  • 21. Data  Analysis:  Periodicity  Among  Days   - Total of 17 Individuals w/ Robust Time Series (>1wk) -  Autocorrelation Technique (99% C.I.; p<0.0001): - Significant Lags (Presence/Absence): - ~90% of 17 individuals had a lag of 1 day- Short-term Patterns: 1-7 days - Long-term Patterns: up to 29 days-  Up to Lag 7 (weekly pattern); -  Up to Lag 29 (monthly pattern) Fish 50364 @ W. Corral Fish 50354 @ Caracoles
  • 22. Data  Analysis:  Periodicity  Within  24  hours   -  Total of 34 Time Series Correlated (1,122 possible comb.) -  In Natural Home Range / Upon Settlement after Displacement -  22 Significant Correlations (17 +; 5 -; (r > +/- 0.926; p<0.0001) - Of 17 positive correlations, 13: significant nocturnal presence -  Diel trends for reef zone utilization: # Time Category Series Key FA 5 FD 5 A= All day and night FN 4 D= Diurnal - Backreefs: All day or nocturnal BA 7 N= Nocturnal BD 0 F= Forereef (no diurnal presence alone) B= Backreef BN 6 TA 1 T= Transition TD 2 C= Channel TN 3 CD 1
  • 23. Acous5c  Monitoring:  Discussion  •  Boundary  Permeability:  nocturnal  use/returns                                                                                               -­‐  Dependent  on  assessing  preda5on  risk?  (Werner & Gilliam 1984)          -­‐  Primary  concern  for  juveniles  (schooling  in  day,  twilight  migra5ons  in  train  of          ind.,  solitary  feeding)?  (McFarland et al. 1979)          -­‐  Adults  recorded  at  same  5me  at  W.  Corral  and  Turrumote:  pairs,  groups?  •  Returns  aler  Displacement                                                                                                     -­‐  Dependent  on  shortest  route  /  magnitude  of  obstacles?        -­‐  Length  of  5me  to  find  shortest  path  shows  learning            (speed  to  return  second  5me  (60609))   Enrique      -­‐  Previous  observa5ons:  adult  displaced  from  Enrique  to            Media  Luna  and  did  not  return  (short  baeery  life  to     1km          confirm  whether  stayed  or  not)  (Tulevech & Recksiek 1994)     Media Luna
  • 24. Acous5c  Monitoring:  Discussion  •  Mul5ple  Receivers:  How  fish  use  area  inhabited        -­‐  Small  por5on  (<300m)  of  poten5al  available  habitat                                                  -­‐  Autocorrela5on  results:  shiling  ac5vity  last  ~1wk      -­‐  Detec5ons  at  nearby  receivers  (using  subparts  of  total  area)                                  •  Shils  in  habitat  use  at  varying  degrees  &  5me  frames            -­‐  Varia5ons  in  frequency  of  detec5ons  at  single  receivers  &  new  loc.  upon      moving  receivers    -­‐  Autocorrela5on  results:  shiling  ac5vity  last  ~1month;  periodic  returns  –    previous  subareas            
  • 25. Acous5c  Monitoring:  Discussion  •  Home  Range:  “area  typically  used  over  some  specified   period  of  5me,  ontogene5c  phase  or  ac5vity”      (Pieman  &  McAlpine  2001)    -­‐  If  cycling  behavior  through  subareas,  only  long-­‐term  records:  full  range  of    movement  •  Technology  Limita5ons:    -­‐  Range/Posi5on  vs.  Movement    -­‐  Detec5on  Capabili5es    (Twilight)  or    (Midday)      
  • 26. Visual  Surveys/Video  Recordings      Examine  distribu5on,  distances  moved,  an5-­‐predator  behaviors  and   rela5on  to  habitat  boundaries  at  Dawn,  Midday  and  Dusk  
  • 27. Visual  Surveys/Video  Recordings:     Study  Sites  -­‐  9  sites  selected  due  to  presence  of  white  grunts  -­‐  18  Visual  Surveys:        3  Dawn  (~06:00),  9  Midday  (~12:00),  6  Dusk  (~18:00)  -­‐  Midday  sites  first-­‐  ID  general  abundances  -­‐  Dawn/Dusk  only  at  sites  w/  suitable  #s  found  Transects:  (<250m)    -­‐  GPS  device/diver;  tracked  waypt.  every  10  sec  -­‐  Visual  surveys  supplemented  with:                                Low-­‐light  Underwater  Video  Recorder          (M. Schärer/D. Mann)  -­‐  4  sites  (Corral  and  Turrumote)    -­‐  Reveal  off-­‐reef  movement/direc5on  in  most                                    natural  setng  (4-­‐10m  off  reef)     M. Schärer
  • 28. Visual  Surveys:  Methodology  I.  Assess  ver5cal  posi5on  on  reef:                                                                                                                                                                                   -­‐  Record  frequency  of  observa5ons  on:    1.  Reef  Crest  (4-­‐8m)    2.  Top  Slope  (8-­‐9m)    3.    Mid  Slope  (9-­‐11m)    4.    Reef-­‐Sand  Interface  (11-­‐16m)        -­‐  Habitat  boundaries  classified  in  terms  of  low  to  high  contrast  II.  Record  distances  moved:    1.  Horizontally  across  seascape  (sand/structure)    2.  Ver5cally  off  sand/structure  
  • 29. Visual  Surveys:  Methodology  III.  Social  grouping:    1.  Forma5on  of  groups  as  an5-­‐preda5on  strategy    2.  Learning                          (Helfman et al. 1982, Bouwmeester 2005)  -­‐  Solitary,  Pairs,  Agg.  3+,  congenerics,  acanthurids,  goavishes,                                                parrovishes,  mix  species    IV.  Boundary  Response  Behaviors:    -­‐  Behaviors  when  solitary  or  in  groups  as  an5-­‐preda5on  strategy                        (Helfman et al. 1982, Rooker & Dennis 2001) -­‐  Hiding,  pale/countershading  colora5on,  convene  &  disperse,  move                                  one  agg  to  another   _____________________________________________________________-­‐  Resemblance/Bray-­‐Cur5s;  SIMPER  Tests:    -­‐  Lifestage  Similari5es  -­‐  Non-­‐parametric  K-­‐W  ANOVA  on  Ranks  Tests:    -­‐  Differences  in  occupancy  of  reef  zone;  lifestage-­‐,  5me-­‐of-­‐day-­‐,  site-­‐            dependent  -­‐  Post-­‐test  Pairwise  Mul5ple  Comparison:    ID  poten5al  drivers    
  • 30. Results:  Distribu5on  on  Reef  -­‐   Observed  more  at  Midday;  scaeered  &       SITE STAGE DAWN MIDDAY DUSK    solitary   W Backreef SA 4 5 3-­‐   Adults  more  abundant  at  Corral/Turrumote   Turrumote A 7 20 5-­‐   WchanR/WRom:  no  adults;  1  SA  at  each   W Backreef SA 3 2 3-­‐   Twilight:  discrete  loca5ons  on  reef  margins   Corral A 6 20 17    adj.  patch  reefs,  f-­‐b  transi5on  zones  
  • 31. Results:                               SUBADULTS ADULTS DAWNLoca5on  on  Reef  -­‐   Subadults/Adults:  Mid  Slope  to              Reef-­‐Sand  Int.  -­‐   Significant  Differences  in            Loca5on   MIDDAY    (K-­‐W  ANOVA  on  Ranks;  p<0.001)  -­‐   Reef-­‐Sand  =  Midslope>Top        Slope>Reef  Crest      (Tukey  Test;  p<0.05)  -­‐   Subadults  con5nually  more     DUSK    present  on  Top  Slope  &  Reef        Crest;  No  adults  observed  on        Reef  Crest  at  Dawn/Midday,  1  at        Dusk  
  • 32. Results:  Loca5on  on  Reef  -­‐   SIMPER  Results  between  lifestages:                                                                                                                                                                -­‐  Dawn:  Highest  (64.5%)   -­‐   Midday:  Lowest  (27.4%)                                                                                                                                                                            (Subadults  encompass  whole  reef,  Adults  mainly  Mid  Slope  to  Reef-­‐Sand  Int.)  -­‐  Kruskal-­‐Wallis  One-­‐Way  ANOVA  on  Ranks:     -­‐   Lifestage-­‐Dependent:    Reef  Crest  (Driven  by  Subadults)   -­‐  Site-­‐Dependent:  Mid  Slope  ,  Reef-­‐Sand  Int.(Higher  rugosity/Ledge  Sys:  WBC/WBT)  
  • 33. Results:    Distances  Moved    -­‐  Maximum  Horizontal/Structure:  Midday  (~45m)    -­‐  Maximum  Ver5cal/Structure:  Dusk  (~1m)   -­‐   Differences  between  lifestages  Midday:   -­‐   Greater  difference  in  max.  off  reef  movement:  2  inshore  sites      (Majimo:  SA:  ~14m  A:  1m;  Caracoles:  SA:  ~6m  A:  1m)                               -­‐   Greater  difference  in  horizontal  movement  on  structure        (WB  Corral:  SA:  44m,  A:  ~8m)     *  Subadult  movement  further   -­‐   Differences  at  Twilight:   -­‐   Twilight  movements  off  reef:  more        site-­‐dependent  than  midday          (Turrumote  at  dawn  (9m),  Majimo  at  Dusk  (12m))     -­‐   Dusk:  Adults  moved  greater  distances  on  structure      at  Corral  (25m)  vs.  Subadults  at  Caracoles  (25m)                                          
  • 34. Results:  Distances  Moved  -­‐   SIMPER  Results  between  lifestages:                                                                                                                                                                -­‐  Dawn:  highest  (for  both  horizontal  and  ver5cal  distances)                                               -­‐  Midday:  lowest  (Subadults  driving  variability,  generally  moved  more)   HORIZONTAL DISTANCES VERTICAL DISTANCES -­‐  No  significant  differences  (K-­‐W  Anova  on  Ranks):  low  sample  size?     -­‐  Video  footage:  Movement  direc5on  inconsistent  among  sites    -­‐  E.  Forereef  Corral:  Both  Direc5ons    -­‐  W.  Corral:  To  Forereef  at  Dawn/  To  Backreef  at  Dusk    -­‐  W.  Turrumote:  To  Backreef  at  Dawn/  Both  at  Dusk  
  • 35. Results:  SOCIAL  GROUPING:  -­‐   Dawn/Midday:  Similar  counts  when  solitary,  in  pairs,  in  agg  3+  -­‐   No  great  difference  between  midday  &  twilight  (except  for  increases  in        numbers  midday)  -­‐   Twilight:  Similar  for  both  lifestages  -­‐   Although  low  counts,  adults  observed:  groups  w/  goavish,  parrovish  &        other  Haemulids    
  • 36. Results:  BOUNDARY  RESPONSE  BEHAVIORS:  -­‐   Both  lifestages  generally  similar  -­‐   Differences  between  5me  periods:      -­‐  Midday  &  Dusk:  Change  to  Countershading    -­‐  Midday:  Convene/Disperse  more  than  twilight  -­‐   Midday:  Only  subadults  moved  from  one  agg  to  another  agg  
  • 37. Results:  Social  Grouping/                                                                                                 Boundary  Response  Behaviors  -­‐   SIMPER  Results  between  lifestages:                                                                                                                                                                -­‐  SOCIAL  GROUPING:  LOW  Similari5es  throughout  day    -­‐  BOUNDARY  RESPONSE  BEHAVIORS:  LOW  Similari5es    (Dawn:  slightly  higher)                                               -­‐  Infer  Lifestage  Differences   GROUPING BOUNDARY BEHAVIORS RESPONE SOCIAL -­‐  Kruskal-­‐Wallis  One-­‐Way  ANOVA  on  Ranks:     -­‐   Lifestage-­‐Dependent:    With  Parrovishes  (Driven  by  Adults)   -­‐  Time-­‐of-­‐Day-­‐Dependent:  Hiding  in  Structure  (Midday)  /Pale  Colora5on  (Dawn)   -­‐  Site-­‐Dependent:  Aggrega5ons  3+  (WBC),  With  Acanthurids  (WBT),  Pale  Colora5on  
  • 38. Visual  Surveys/Video  Recordings:   Discussion   Significant  differences  in  observed  behaviors  (interpreted  as  reducing  preda5on                    threat)  can  occur  as  func5on  of  lifestage,  loca5on  and  5me  of  day            Adults  less  likely  to  move  off  reef  at  night;  reducing  vulnerability  to  stay  on  or  near  reef   (greater  food  resources)  vs.  subadults  -­‐  s5ll  may  reflect  juvenile  behaviors  to  avoid   preda5on  and  leave  reef  at  night    (Appeldoorn et al. 1997, 2009, Tulevech & Recksiek 1994)         -­‐  Subadults  &  Adults:  Mid-­‐Slope  to  Reef-­‐Sand  Interface  (high  contrast)                -­‐  Subadults:  remain  in  denser  gorg.  mid-­‐  to  top-­‐slope  (low  contrast) Highest  Similari5es  between  Lifestages:  Twilight  (Dawn)  -­‐preda5on  risk  greater?    Similari5es:  Visual  Surveys  vs.  Video  Footage    -­‐  Poten5al  pre-­‐migratory  behaviors    -­‐  Use  of  sand  channels  on  slope,  within  reef  structure  &  Reef-­‐Sand  Interface  as  corridors    -­‐  Communica5on  through  grun5ng  sounds  at  Twilight      Footage  supports  idea:  in  absence  of  predators/divers,  fishes  increase  range  of  movement      Both  techniques  will  aid  in  beeer  understanding  of  behavioral  movement  paeerns/   lifestage  differences  
  • 39. Visual  Surveys/Video  Recordings:   Discussion   Interpreta5on  at  larger  scale      VISUAL  SURVEYS                    ACOUSTIC  MONITORING   -  Visual surveys at reefs w/ minimal -  Absence of detections at connectivity (Corral/Turrumote) show receivers may not imply do not move much off main reef boundary-crossing -  Distances moved horiz. on structure: - Not departing but nearby in Midday (Subadults:16.4m; Adults:11.7m) 250-m range Twilight (Subadults:10.5m; Adults:9.3m) -  Distances moved horizontally off -  Movements on/off structure may structure: Twilight (both: ~3m) cause variations at different times of day
  • 40. Visual  Surveys/Video  Recordings:   Discussion   Interpreta5on  at  larger  scale      VISUAL  SURVEYS              ACOUSTIC  MONITORING   - Solitary subadult moved after 5 -  Adults moved after several attempts - patch reef/main reef (Majimo) nights of attempts to cross Corral to Turr - Greater subadult movement at home -  Displaced subadults ~1km reefs w/ greater connectivity; off-reef across sand channel (Corral/ movement Turr) no return - Adults with smaller range of movement -  Displaced adults did return * Range of movement not the only factor controlling ability to return: navigational experience?/ predation threat?
  • 41. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®             Examine  spa5al  paeerns  of  recep5on  range  rela5ve  to             geomorphology    vs.  line-­‐of-­‐sight  theory  
  • 42. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Study  Area   -­‐   11  selected  points  out  of  76  total        receiver  loca5ons   -­‐   Poten5al  range  limits  assumed  to  be   same  for  all  receivers  /  dependent   only  on  site  in  rela5on  to   geomorphology  of  benthos,  habitat   structure  &  composi5on   -­‐   Selected  points  reflected  full   variability:   1.  Open  Sand   2.  Reef-­‐Sand  Interface   3.     On  Slope   4.     Mixed  Habitat/Reef  Crest  
  • 43. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Methods   Detection Range Testing -­‐   4  transects  at  each  point:  within  250-­‐m  radius   -­‐  Receiver  placements  (1.5m  off  boeom);        Excep5ons:  Reef-­‐Sand  (2.1m)  &  Open  Sand          (1.5/3m)  to  test  varia5ons  in  range  limits   -­‐   V7  transmieer:  10-­‐second  interval   -­‐   Waypts.  recorded  every  30  sec.  (up  to  3  detec5ons/waypoint):                                                        imported  to  ArcMap   Boat-based Transects Diving Transects
  • 44. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Methods   Viewshed Application Line-of-sight Theory -­‐   Input  data:  Receiver        Loca5on,  Distance      off  boeom  &          Bathymetry  within  250-­‐m        radius   -­‐   Output  data:  Visible  &        Not-­‐Visible  Areas       Verifying Viewshed Evaluate  sources  of  error:      -­‐  Combine  modified  benthic  map  &  Viewshed’s  final  map  to  quan5fy  habitat          types  &  ranges  of  degrees  of  slope  to  assess  driving  factors  for  detec5on            limita5ons        (  1.  Areas  where  transmieer  was  detected  when  it  shouldn’t  have  been;            2.  Areas  where  transmieer  was  not  detected  when  it  should  have)   -­‐  K-­‐W  ANOVA  on  Ranks  tested  variability  among  loca5on  types  
  • 45. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Results  -­‐   Viewshed  outputs  coupled  w/   Open Sand (1.5m) Open Sand (3m)      Range-­‐tes5ng  at  4  loca5ons    -­‐   Detec5ons  tend  to  occur      closer  to  receiver  -­‐   Waypts.  w/  no  detec5ons  tend      to  occur  closer  to  limits  -­‐   Open  Sand:  placement  at        different  depths  -­‐  variability  -­‐   When  receiver  closer      to  boeom,  detec5ons      recorded  further;  with      higher  placement,      detec5ons  recorded        closer  to  receiver       Reef-Sand Interface On Slope Reef Crest
  • 46. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Results  -­‐   Strong  posi5ve  correla5on        between  #  detec5ons  in     r=0.949; p<0.0001    visible  area  vs.  total        detec5ons  -­‐   On  Slope  &  Mixed  Habitat:        Most  effec5ve  reef  loca5ons  -­‐   Mixed  Habitat:  Max.  Range        Total  Detec5ons    -­‐  Higher  correla5on  in  Open        Sand  vs.  Reef-­‐Sand  Interface      (curvature  &  slope  of  main      reef  creates  interference      from  line-­‐of-­‐sight)  -­‐   Two  Reef-­‐Sand  Pts.  outside  95%  C.I.  show  highest  variability/  ineffec5veness?  -­‐   Reef-­‐Sand  point  with  highest  correla5on  -­‐  2.1m  off  boeom,  may  be  more  effec5ve        higher  off  boeom    
  • 47. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Results   Max Dist Ave Max Dist/ Location Receiver (m) Location (m) Mixed DIS3 (4799) 0 40 (w/DIS3) Habitat PT 342 70 60 (w/o DIS3)-­‐   Detec5on  distances       VRS3 51    (max=216m)  greatest  for         On Slope VRS2 38 30 VRS4 15    Open  Sand  (s5ll  <250-­‐m  radius)   VRS6 37-­‐   Next  greatest  (114m)-­‐  Reef-­‐Sand   Reef-Sand PT 315 73 96 (@ 1.5m) Interface PT 323 114-­‐   Mixed  Habitat  -­‐  most  varia5on   VRS5-4802 (1.5m) 100 VRS5-10345-­‐   On  Slope  -­‐  least  range  (38m)   8(2.1m) 83-­‐   Total  Average  Max.  Dist.-­‐  72m   Open Sand PT 343 (1.5m) 216 114 (@ 1.5m) PT 343 (1.5m) 147 82 (@ 3m) PT 343 (3m) 81 PT 343 (3m) 60 PT 344 (1.5m) 82 PT 344 (1.5m) 14 PT 344 (3m) 117 PT 344 (3m) 70 Total average maximum distance detected 72
  • 48. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Results   •  Reliability  of  Viewshed  evaluated  rela5ve  to  error:   -­‐  Sta5s5cally  significant  differences  in  %  detec5ons  within  Not-­‐Visible  Area  for  all  habitat   types  (K-­‐W  ANOVA  on  Ranks;  p<0.05)   -­‐  Reef-­‐Sand:  Most  Problema5c  (greatest  %  detec5ons  in  Not-­‐Visible  Area)   -­‐  On  Slope:  Low  errors  for  both   -­‐  Mixed  Habitat:  Accurate  (all  detec5ons  in  visible  area);  lowest  detec5on  rate       -­‐  More  reliability  w/  Open  Sand  (3m);  trade-­‐off  between  detec5on  range  vs.  accuracy    
  • 49. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Results  -­‐   Output  for      all  76  loca5ons  -­‐   Overall  results        (esp.  on  slope):      Off-­‐reef:  Not-­‐Visible  -­‐   Contradicts  prior      ideas  of  detec5on        capabili5es  within      line-­‐of  sight    (from        slope,  sand  -­‐  visible)  
  • 50. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Results:  Habitat  in  Visible/Not-­‐visible  Areas   Open Reef-Sand Sand Interface-­‐   Dominant   (n=2) (n=51)    Habitat  Types:      Not-­‐  Visible:      Unknown/    Sand      Visible:  Linear  Reef   On Mixed Slope Habitat (n=9) (n=14)
  • 51. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Results:  Slope  in  Visible/Not-­‐Visible  Areas   -­‐   Low  slope:  Greatest  propor5on  for  both   Slope    (Contradicts  prior  ideas:  greater  slope,  less  visibility)   Slope (Degrees) Class 0 - 1.103 1 -­‐   Ave.  slope:  Not-­‐Visible  Area       1.103 - 3.309 2    (excep5on:  Mixed  Habitat-­‐  more  heterogeneity)   3.309 - 6.342 3 6.342- 10.203 4 -­‐   Open  Sand:  Least  Range  in  Visible  (14    deg.  limit);       10.203 - 14.615 5    Class  9  included  in  Not-­‐Visible   14.615 - 20.130 6 20.130 - 26.747 7 -­‐  Greatest  variance:  Reef-­‐Sand  (Not-­‐Visible);                                       26.747 - 35.020 8    On  Slope  (Visible);  curvature  of  reef  driver  for     35.020 - 52.392 9    interference   52.392- 70.315 10 -­‐   StDev:  On  Slope  -­‐  Not-­‐visible  areas  more  effec5ve  w/  Viewshed     -­‐   Slightest  slope   Average Slope Range Variance StDev    differences     Not- Not- Not- Not-    enough  for   Location Visible Visible Visible Visible Visible Visible Visible Visible    detec5on   Open Sand 3.26 2.19 1--9 1--5 3.28 1.42 1.81 1.19 Reef-Sand Int. 4.15 3.80 1--10 1--10 4.24 4.35 2.06 2.08    limita5ons   On Slope 4.22 4.07 1--9 1--9 4.19 4.81 0.24 2.19 Mixed Habitat 3.83 3.86 1--9 1--9 3.61 4.01 1.90 2.00
  • 52. Applica5on  of  Acous5c  Telemetry  vs.  Viewshed®:     Discussion   •  Viewshed:  useful  tool  to  ID  areal  detec5on  limits  by  acous5c  receivers   •  Propor5on  detec5ons  high  in  Visible  areas  (despite  varia5on  by  loca5on)   •  Certain  cases  where  line-­‐of-­‐sight  theory  incorrect:  open  sand  &  low  slope   in  Visible  areas   •  Limita5ons:  proper5es  of  sound  transmission,  behavioral,  ecological  &   social  characteris5cs  of  tagged  species   •  Rugosity,  habitat  type,  boeom  layer  (wave  surge,  suspended  sediment):   create  interference  not  ID’d  by  Viewshed   _____________________________________________________ •  Adjustments  to  bathymetry  layer  to  include  rugosity  (smaller  resolu5on)   may  facilitate  interpreta5on  of  residency/movement  paeerns  off  reef     •  Future  tracking  studies:  closer  arrays  (corridor  of  overlapped  ranges:  Reef                  Crest  (~40m)  to  Slope  (~30m)  to  Interface  (~96m)  to  Open  Sand  (~82m  @  3m)  
  • 53. Overall  Conclusions  Acous5c  Telemetry:      Characterize  movements  &  shiling  paeerns  over  5me  &     responses  to  poten5al  boundaries  at  various  scales      Displacement:  boundary  permeability  depends  on  body  size  &   learning    Boundary-­‐crossing:  larger  body  size,  short  distance,  connec5vity,   twilight/nocturnal  periods    Short-­‐term:  low  light  levels  at  twilight  reduce  contrast,  ini5ate   movement    Long-­‐term:  environmental  stressors  may  ini5ate  larger  shils    Both  lifestages  spend  days,  weeks,  months  near  or  away  from   discrete  loca5ons  limited  to  ~300m  range    Backreef  areas:  used  all  day  or  only  at  night  (not  diurnal  only)    Primary  pathway  at  forereef-­‐backreef  transi5on  areas:  reef-­‐ slope-­‐sand  interface  
  • 54. Overall  Conclusions  Visual  Surveys  /  Video  Recordings:      Significant  rela5onship  among  habitat  structure  &  distribu5on  &  daily   distribu5on,  movement  &  behaviors  of  white  grunts    Subadult  ac5vity/range  of  movement  greater;  occupy  similar  space    Adults  remain  on  reef  despite  higher  risk;  Subadults  s5ll  reflect  need  to  move   off  reef  to  avoid  preda5on    Recommenda5ons:  show  results  to  compare  w/  mid-­‐  to  late-­‐juvs    Cross-­‐boundary  moves  facilitated  by  habitat  connec5vity  w/  minimal   thickness/contrast,  twilight,  grouping  w/  similar-­‐sized  fish    Barriers/Corridors:  slope  changes,  transi5on  zone,  abundance  of  sol  coral   cover,  ledge  systems    Obs.  Behaviors:  lifestage-­‐dependent  (adults  w/  dissimilar  sp.,  subadults  on   reef  crest),  5me-­‐of-­‐day-­‐dependent  (hiding,  pale),  site-­‐dependent  (social   structure  of  agg  on  slope)    Environmental  cues:  light  changes  during  twilight    Voluntary  habitat  changes:  decrease  w/  inc.  body  size,  inc.  w/presence  of   conspecifics/congenerics,  proximity  adj.  structure    
  • 55. Overall  Conclusions  Acous5c  Telemetry  vs.  Viewshed  ®:      Spa5al  Analyst’s  Viewshed:  effec5ve  planning  tool  to  assist  efficient   monitoring;  ID  smaller-­‐scale  habitat  use/home  range  boundaries    Limita5ons  based  on  line-­‐of-­‐sight:  one  factor  affec5ng  ability  to  detect   acous5c  signals  (acous5c  capabili5es  in  water/boeom  layer  interference)  Applica5on  to  Fisheries  Management:      Complex  movement  paeerns  over  5me  -­‐  quan5fica5on  of  home  ranges    Marine  Reserves  to  fulfill  conserva5on  func5on:  accurate  designa5on  of   reserve  boundaries  large  enough  to  encompass  full  range  or  networks  along   pathways:  account  for  daily,  intermediate  &  ontogene5c  movements      Avoid  cutng  through  reef  plavorms  (e.g.,  300m  range)    Only  adults  crossing  large  boundaries:  Marine  Reserve  networks  consider   movement  capabili5es  (inshore,  mid-­‐shelf,  shelf-­‐edge)    Digi5zing,  modifica5on,  enhancement  of  benthic  habitat  maps  &  spa5al   analyst  mapping  techniques  allow  for  accurate  ID  of  habitat  u5liza5on   paeerns,  facilitate  future  planning    for  conserva5on  management  
  • 56. Acknowledgements   -Dr. Appeldoorn -Graduate Committee -Department of Marine Sciences -Fish Lab -Tag Team CRESCSCOR
  • 57. Ques5ons?