Plant seed dispersal by two frugivorous Amazonian fish

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Plant seed dispersal by two frugivorous Amazonian
fish
 

• F. Chu-Koo
• C. Kohler, W.Camargo, F. Alcántara
• L. Rodríguez

CRSP- IIAP-SIUC
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Funding for this research was provided by the
Pond Dynamics/Aquaculture Collaborative
Research Support Program (PD/A CRSP)

• The PD/A CRSP is funded in part by USAID and by
  participating institutions.

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Seed dispersal in tropical forests Wind
(Anemocory) Water (Hydrocory) Animals (Zoocory)

• Animals
• Monkeys
• Bats
• Birds
• Terrestrial mammals

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Recently, turtles and fish were included as
potential plant seed dispersers
However, researchers studies have been based
almost entirely on circumstantial evidence
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According to Goulding (1980), fish swim into the
flooded forest and feed on 200 fruits and seeds
as these reproductive products fall into the
water
These fish may disperse a variety of seeds along
the Amazon Basin and therefore their conservation
is extremely important
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Main goals of the Study
1) Determine seed dispersal potential by 2
migratory frugivorous fish from the Amazon region
2) Determine effect of fish digestive system over
germination rate of ingested seeds
3) Assess effect of fish size over germination
rate of ingested seeds
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MATERIAL AND METHODS
Study Site Instituto de Investigaciones de la
Amazonía Peruana-IIAP. Iquitos (Northeast of
Peru) Duration From June 2002 to February 2003
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Photo by Maria Luiza Delgado Assad
Piaractus brachypomus
Colossoma macropomum
Family CHARACIDAE
Family CHARACIDAE
Common names Gamitana (Peru), Cachama
negra (Colombia), Cachama (Venezuela), Tambaqui
(Brazil) and Black-finned Pacu (USA)
Common names Paco (Peru),
Morocotó (Venezuela) Cachama blanca (Colombia),
Pirapitinga (Brazil) and Red-belly Pacu (USA)
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SEEDS STUDIED

• Pseudobombax munguba punga
• Family Bombacaceae

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2. Hevea brasiliensis shiringa Family
Euphorbiaceae
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3. Bactris gasipaes pijuayo, pejibaye Family
Arecaceae
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4. Psidium guajaba guayaba, guava Family
Myrtaceae
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5. Piranhea trifoliata sardina caspi Family
Euphorbiaceae
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6. Strychnos erichsonii Tocón huayo Family
Loganiaceae
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7. Bactris concinna ñejilla Family Arecaceae
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8. Myrciaria dubia camu-camu Family Myrtaceae
Photo courtesy of Ms. Leslie Taylor of Raintree
Nutrition, Inc.
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Experimental Design
Objective 1 To assess if these fish species can
actually be seed dispersers in nature

• Step 1. Fish were placed randomly into 6 m3
  cages
• Step 2. Fish were starved during 48 h, to allow
  digestive system clean up
• Step 3. Fish were fed until satiation

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Experimental Design - Cont

• Step 4. After verifying fruit or seed
  consumption, fishes were placed into individual
  tanks to collect their feces

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Experimental Design - Cont

• Step 5. Entire seeds collected from fish feces
  were sowed into sterilized humus

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Experimental Design - Cont

• Step 6. Germination of digested and undigested
  seeds were verified

• Step 7. Germination rate for digested and
  undigested seeds were calculated for each
  treatment

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Experimental Design - Cont
Objective 2 To assess if ichthyocory enhances
seeds germination rate. Treatment 1
(Ichthyocory) Seeds collected from fish feces
were sowed in sterilized humus
Treatment 2 (Anemocory) Seeds collected from
fruits were left exposed for 2 days to local
environmental conditions and then sowed to
simulate dispersion by the wind
Treatment 3 (Hydrocory) Seeds collected from
fruits were placed in the water (hanging in the
cages) for 2 days and then sowed to simulate
dispersion by water
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Experimental Design - Cont
Objective 3 To assess if fish size does enhance
germination rate of ingested seeds
Fishes were divided in 3 different groups Group
1 Three fish lt 1 kg Group 2 Three fish 1 to 3
kg Group 3 Three fish gt 5 kg
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RESULTS AND DISCUSSION
Do these seeds germinate after being ingested by
fish?
Can these fish species be seed dispersers in the
Amazon floodplain areas?
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RESULTS AND DISCUSSION
Table 1. Potential of seeds to be dispersed by C.
macropomum and P. brachypomus
Seeds Colossoma
Piaractus Seed
size
tested
Psidium guajaba Yes
Yes 2.5 mm P. munguba
Yes --- 3.5
mm Piranhea trifoliata ---
No 7.0 mm Myrciaria dubia
Yes Yes 10.0 mm
Strychnos erichsonii ---
Yes 14.0 mm Hevea brasiliensis
No No 15.0
mm Bactris concinna No
--- 15.0 mm Bactris gasipaes
No --- 20.0 mm
Tritured seeds
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RESULTS AND DISCUSSION
Is ichthyocory really important?
Does fish digestive system enhance seed
germination?
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RESULTS AND DISCUSSION
Table 2. Seed germination rates () from 5 fruit
species obtained from paco (P. brachypomus),
gamitana (Colossoma macropomum) and compared with
wet and dried seeds (a 0.05)
Germination rate observed Fruits offered
Seed size Paco Gamitana Hydrocory
Anemocory P-Value Decision Guava
2.5 mm 32.11 42.67 38.01
15.71 0.4245 N.S. Punga
3.5 mm --- 79.65 56.92
40.88 lt0.001 H.S Sardina
caspi 7.0 mm 38.03 ---
71.66 30.00 0.0018 H.S
Camu-camu 10.0 mm 78.66 90.89
74.58 41.99 lt0.001
H.S Tocón-huayo 14.0 mm 39.60
--- 41.47 55.52
0.0869 N.S
Shiringa, Ñejilla and Pijuayo did not germinate
(broken seeds)
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RESULTS AND DISCUSSION
Does fish size enhance the germination rate of
ingested seeds?
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RESULTS AND DISCUSSION
Table 3. Seed germination rates () from 5 fruit
species fed to paco (Piaractus brachypomus) and 6
fruit species fed to gamitana (Colossoma
macropomum) at three different weight groups (a
0.05) Paco (germination
rate) Gamitana (germination rate) Fruits
offered Seed size 1kg 3kg 5kg
P-Value 1kg 3kg 5kg
P-Value Guava 2.5 mm 34.8
32.6 SB 0.6980 49.4 54.2 50.7
0.6503 Punga 3.5 mm --
-- -- --- 81.7
75.3 82.7 0.2672 Sardina caspi 7.0
mm BS 32.0 50.0 0.8220 --
-- -- --- Camu-camu
10.0 mm BS 75.0 75.0 0.9543
90.3 77.3 94.3 0.4369 Tocón-huayo
14.0 mm 36.3 56.2 BS 0.2762
-- -- -- ---
Shiringa (15.0 mm), Ñejilla (15.0 mm) and Pijuayo
(20.0 mm) did not germinate (broken seeds)
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CONCLUSIONS

• In Colossoma macropomum
• Only three out 6 seeds (punga, camu-camu and
  guava) might be likely dispersed by this fish sp.

• Shiringa, ñejilla and pijuayo seeds could not
  germinate probably because of their size (gt15mm)
  and hardness which obligate fish to break down
  before ingesting them

• Punga and camu-camu seeds after passing
  throughout fish digestive system proved to have
  better viability than seeds supposedly dispersed
  by water and wind (Plt0.001)

• Fish weight (size) did not have a significant
  effect on seed germination rate (guava P0.6980,
  sardina caspi P0.822, camu-camu P0.9543 and
  tocón-huayo P0.2762)

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CONCLUSIONS- P. brachypomus

• Four out 5 seeds (coto-huayo, camu-camu, sardina
  caspi, and guava) may be dispersed by this fish

• Like in Colossoma shiringa seeds might not be
  dispersed by P. brachypomus probably because of
  their size and hardness

• Fish size does not have a significant effect on
  germination rate (Guava P0.6980, Sardina caspi
  P0.822, Camu-camu P0.9543 and Tocón huayo
  P0.2762

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FINAL CONCLUSION
Our results demonstrate that both frugivorous are
active seed dispersing agents and they likely
play an important role disseminating seeds in the
flooded Amazon forest
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Thank You, any questions?
Pictures credits Instituto de Investigaciones de
la Amazonía Peruana Sociedade Civil
Mamirahua/CNPq/Rainforest Alliance Carlos
Araujo-Lima and Michael Goulding Dr. Fernando
Alcántara (IIAP) Blgo. Luciano Rodríguez
(IIAP) www.peru.com Others
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Piaractus brachypomus
Paco (Peru), Morocoto (Venezuela) and
Pirapitinga (Brazil)

1. Camu-camu
2. Tamara
3. Guava
4. Punga
5. Shiringa
6. Pijuayo
7. Hipururo

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RESULTS AND DISCUSSION
Fig. 5. One-way analysis for germination rate of
tocón huayo seeds by groups
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RESULTS AND DISCUSSION
Fig. 1. One-way analysis for germination rate of
camu-camu (Myrciaria dubia) seeds by groups
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RESULTS AND DISCUSSION
Fig. 2. One-way analysis for germination rate of
guava (Psidium guajaba) seeds by groups
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RESULTS AND DISCUSSION
Fig. 3. One-way analysis for germination rate of
punga (Pseudobombax munguba) seeds by groups
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RESULTS AND DISCUSSION
Fig. 4. One-way analysis for germination rate of
sardina caspi (Piranhea trifoliata) seeds by
groups