Larvae. Juvenile. Adult. Bipartite life cycle of benthic marine fishes with pelagic larvae. Pelagic Environment. settlement.

Transcription

1 13 - Marine Ecology

2 Bipartite life cycle of benthic marine fishes with pelagic larvae Larvae survive, grow, develop, disperse reproduce Pelagic Environment Benthic Environment settlement Adult Juvenile survive, grow, mature

3 Bipartite life cycle of benthic marine fishes with pelagic larvae

4 Closed Populations Open Populations Production Supply Production Supply Little or no exchange among populations Significant exchange among populations Production Supply Supply Production Decouples local production and supply

5 Pelagic duration - a proxy for dispersal potential Dispersal Distance (km) invertebrates fish Predicted by passive dispersal Propagule Duration (hr) Shanks et al Ecological Applications

6 Larval duration of 24 coastal fish species from western North America SPECIES Larval duration midpoint (range) Shanks et al Ecological Applications MEAN = 94 days

7 Indirect Estimates of Larval Fish Dispersal Distances Pelagic-duration Isolation by distance Dispersal Distance (km) = 30 days Fish m 10 m 100 m 1 km 10 km 100 km 1000 km Estimated dispersal scale Kinlan & Gaines 2003 Ecology Palumbi 2003 Ecological Applications Propagule Duration (hr) Shanks et al Ecological Applications 10 s to 100 s of km

8 The paradigm shift Generally assumed that larvae disperse away from natal population

9 Anemonefish recruitment study - Moorea, French Polynesia

10 1. Surveys Manta Tows Scuba Diving

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12 2. Characteriza;on

13 3. DNA material

14 A material

15 3. DNA material

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17 4. Return the fish

18 4. Return the fish

19 5. Sampling locality database

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21 Location of all Amphiprion chrysopterus collected around Moorea (French Polynesia) >21 individuals

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23 Moorea, PGEM

24 Recruitment studies demonstrate spillover effect Harrison et al. 2012

25 Potential consequences of larval dispersal: local recruitment (replenishment) not necessarily tied to local production recruitment critical to replenishment of local populations local replenishment reliant on recruitment of larvae produced elsewhere open spatial structure of local and regional populations openness decreases as likelihood that larvae return to adult population increases

26 Recruitment is important and fascinating Temporal scale 100 yrs 1 decade 1 year 1 month 1 week 1 day 1 hour 1 min Langmuir cells Seagrass beds Turbulent eddies Surface waves Plankton migration Kelp forests Internal waves Seasonal current shifts Small-scale fronts, plumes, runoff Seasonal upwelling Mesoscale eddies Surface tides Internal tides Coastally trapped waves PDO ENSO Coastal filaments, Upwelling / relaxation 1 cm 1 dm 1 m 10 m 100 m 1 km 10 km 100 km 1000 km km After T. Dickey, unpublished Linear spatial scales but its very complex!

27 Recruitment is important and fascinating Temporal scale 100 yrs 1 decade 1 year 1 month 1 week 1 day 1 hour 1 min Larval production Langmuir cells Seagrass beds Turbulent eddies Surface waves Plankton migration Kelp forests Internal waves Seasonal current shifts Small-scale fronts, plumes, runoff Seasonal upwelling Mesoscale eddies Surface tides Internal tides Coastally trapped waves PDO ENSO Coastal filaments, Upwelling / relaxation 1 cm 1 dm 1 m 10 m 100 m 1 km 10 km 100 km 1000 km km After T. Dickey, unpublished Linear spatial scales but its very complex!

28 Recruitment is important and fascinating Temporal scale 100 yrs 1 decade 1 year 1 month 1 week 1 day 1 hour 1 min Larval dispersal, mortality Langmuir cells Seagrass beds Turbulent eddies Surface waves Plankton migration Kelp forests Internal waves Seasonal current shifts Small-scale fronts, plumes, runoff Seasonal upwelling Mesoscale eddies Surface tides Internal tides Coastally trapped waves PDO ENSO Coastal filaments, Upwelling / relaxation 1 cm 1 dm 1 m 10 m 100 m 1 km 10 km 100 km 1000 km km After T. Dickey, unpublished Linear spatial scales but its very complex!

29 Recruitment is important and fascinating Temporal scale 100 yrs 1 decade 1 year 1 month 1 week 1 day 1 hour 1 min Larval settlement Langmuir cells Seagrass beds Turbulent eddies Surface waves Plankton migration Kelp forests Internal waves Seasonal current shifts Small-scale fronts, plumes, runoff Seasonal upwelling Mesoscale eddies Surface tides Internal tides Coastally trapped waves PDO ENSO Coastal filaments, Upwelling / relaxation 1 cm 1 dm 1 m 10 m 100 m 1 km 10 km 100 km 1000 km km After T. Dickey, unpublished Linear spatial scales but its very complex!

30 Sources of spatial and temporal variation in recruitment Larval dispersal Settlement Larval production Post-settlement

31 Sources of spatial and temporal variation in recruitment Larval production: - adult fecundity (eggs per female) size structure / sex ratio adult condition - adult abundance

32 Offspring production: climatic variability Holbrook et al Ecological Applications Ocean climate change Surfperch production Population responses (4 species) Benthic productivity Perch recruitment (Love et al Fishery Bulletin) Power plant studies: (Brooks et al Mar. Freshwater Res.) - Bight-wide patterns of juvenile impingement - declines in recruitment for many spp. ( ) - attributed to reduced production (but maybe larval survival) - reflecting large-scale decline in productivity

33 Sources of spatial and temporal variation in recruitment Larval dispersal (direction, distance, delivery): - larval duration - larval behavior - oceanographic features - interaction among these Larval production: - timing of reproduction - location of reproduction

34 Physical processes and larval behavior (1) Larval cues: (light, pressure, temperature, structure) e.g., Norris 1963, Ecological Monographs - Opaleye (Girella nigricans) - recruitment related to tide pool temp. - lab experiments: thermal preference - coast-wide patterns of recruitment - hypothesized mechanisms of larval delivery: - internal waves - thermal / structural cues - upwelling ONSHORE TRANSPORT Shanks 1983 Mar. Ecol. Prg. Ser.

35 Olive rockfish Structure - schooling Long larval duration (3-4 months) Yellowtail rockfish Black rockfish Kelp rockfish Benthic - solitary Short larval duration (1-2 months) Gopher rockfish Black-&-yellow rockfish

36 Physical processes and larval distribution (2) shifts in vertical distribution with ontogeny -- upwelling e.g., Larson et al. 1994, Lenarz et al. 1995, CalCOFI Rpt.s - vertical distribution of early and late larval rockfishes proportion structure - schooling spp. benthic - solitary spp. depth (m) depth late larvae pelagic juveniles early larvae kelp bed onshore offshore

37 1.0 Lenarz et al CalCOFI Mid-water complex Long larval duration (3-4 months) Olive, Yellowtail and Black rockfish Proportion Kelp, Black-&-yellow, and Gopher rockfish Benthic complex Short larval duration (1-2 months) Relative Abundance El Nino La Nina La Nada (1998) (1999) (2000)

38 (1998) (1999) (2000) Kelp rockfish Gopher rockfish Relaxation Black-&-yellow rockfish Benthic complex Short larval duration (1-2 months) Fish per 240 m 3 20 Kelp, Black-&-yellow, and Gopher rockfish El Niño La Niña Normal

39 (1998) (1999) (2000) Mid-water complex Long larval duration (3-4 months) Upwelling Olive rockfish Yellowtail rockfish Fish per 240 m Olive, Yellowtail and Black rockfish Black rockfish El Niño La Niña Normal

40 Sources of spatial and temporal variation in recruitment Settlement: - larval cues - habitat structure - priority effects conspecific cues predation competition

41 Settlement (post-settlement): habitat structure Kelp Bass Recruit Density 3 (Number / 60 m ) 2 (Number / 10 m ) B B A Blade Biomass Per Reef Area 2 (grams / 10 m ) Carr Ecology ,200 B B 800 A Macrocystis Density (stipes / 30 m )

42 Sources of spatial and temporal variation in recruitment Settlement: - larval cues - habitat structure - priority effects conspecific cues predation competition Not a lot of information!

43 Sources of spatial and temporal variation in recruitment Early post-settlement: - survival - growth - movement predation competition

44 Early post-settlement: predation 1.0 per-capita mortality kelp perch Anderson 2002 Ecology black eyed goby Initial density predators present predators absent 1.0 Steele 1997 Oecologia kelp rockfish Johnson unpublished

45 Early post-settlement: competition Conspecific and interspecific resident effects e.g., Steele 1997a, Ecology - black-eyed and blue-banded gobies in So. California - manipulated presence of adults of both - settlement of black-eyed (-) influenced in presence of adult conspecifics - settlement of black-eyed not influenced by presence of adult blue-banned - settlement of blue-banded (+) influenced in presence of adult conspecifics - settlement of blue-banded not influenced in presence of adult black-eyed

46 Sources of spatial and temporal variation in recruitment - survival - growth - movement competition predation Late post-settlement: adult and juvenile interactions

47 Role of fishes in kelp forest communities (1) Keystone predator -- trophic cascades e.g., Cowen 1983, Oecologia - sheephead (Semicossyphus pulcher) in So. Calif. - manipulated local presence of sheephead and observed red sea urchin behavior - urchins more exposed and mobile in absence of sheephead

48 Cascading Effects of Predator Removal Southern California Central California lobster sheephead sea otters sea urchins rockfishes barrens kelp forest

49 Another example from down under: New Zealand snapper Sea urchin banded wrasse barrens Ecklonia

50 Role of fishes in kelp forest communities (2) Enhanced nutrient availability and productivity e.g., Bray et al. 1981, Science - planktivorous blacksmith (Chromis punctipinnis) hole up in crevices at night - monitored nutrient availability and macroalgal production in crevices with and without blacksmith - greater nutrient availability and macroalgal production in crevices with blacksmith - example of planktivorous fishes directing planktonic production to benthos

51 Role of fishes in kelp forest communities (3) Planktivorous fishes reducing larval supply e.g., Gaines and Roughgarden 1987, Science - reduced recruitment of intertidal barnacles in years with thick Macrocystis forest at Hopkins - high recruitment of planktivorous juvenile rockfishes in years with thick Macrocystis forest - could be hydrodynamic influence of kelp or predation by planktivorous juvenile rockfishes - used barnacle molts to decouple potential causes - barnacle molts not reduced as they passed through forest, concluded reduction due to planktivory

52 Percentages Average = ~ 76 High Score = 94 Low Score = 53 Midterm Results Points Total possible points pts for scantron + 48 points for written