Dariusz Nowak
School of Natural Sciences
National University of Ireland Galway
Aims

Development of new, efficient and cost effective baited
trap protocols.

Specific (target) benthic invertebrate sampling.

Focus on invertebrate taxa which may not be
numerically abundant but are identified as being
important for monitoring subtle anthropogenic change
in lake ecosystems.
Study Area







Lough Mask is the 6th largest
lake in Ireland located in the
west.
It is part of the Corrib
Catchment which has a total
area of ~3,000km2.
Total area of 82.75km2.
Max. depth ~58m
Axial length ~16km.
Oligotrophic/Mesotrophic.
1
3 littoral areas were selected
for field experiments.
GIS Licence No. NUIG200803
GIS Data: OSI
2
3
Turbellaria: Tricladida.

Selected species: Polycelis nigra, Dugesia polychroa
and Dendrocoelum lacteum.
Dendrocoelum spp.

Free-living, freshwater flatworms that live on bottom
substrates such as mud, stones, macrophytes
and submerged objects.

These 3 taxa were selected because of their relative
abundance in the study area and their slow,
easily observed movement.
25
Dugesia spp.
Species Abundance
N / m2
20
15
10
5
0
D. lacteum
D. polychroa
P. nigra
Polycelis spp.
Laboratory Experiments





Choice-chambers were used to assess individual species responses to
alternative bait types (2 bait types, 30 flatworms per experiment).
6 bait types or a control (water only) as potential attractants
(or repellents) were evaluated.
Baits were homogenised, organic material (A – F) stored at -20 °C
prior to the experiment to ensure standardised test protocols.
Responses of each species were tested (3 repeats per bait type),
noted and observed using an infra-red video camera.
Experiments were conducted at night, in darkness in an isolated
laboratory environment.
Bait types:
A. - Lumbricus tissue,
E.
B. - fresh Rutilus tissue,
F.
C. - decomposing Rutilus tissue,
G.
D. - chironomid/oligochaete tissue,
- fish viscera,
- Potomogeton crispus,
- control (empty).
Apparatus
An apparatus was designed and constructed in order to determine
preferred bait types for each group of triclad.
 The apparatus was made up of 10 channels with fresh water collected
from L. Mask flowing through the channels.
 Each channel had a choice-chamber (N=10) in the middle and a bait
chamber (N=20) at each end.
 The apparatus was calibrated, so that the speed of water flowing from
a tap in each bait chamber and along each channel was the same.

Bait
chamber
Choice
chamber
Flow
Tap
Outlet
Laboratory Experiments
Results



Most attractive bait was identified for each
group.
D. lacteum: decomposing Rutilus tissue,
Dugesia spp. : chironomid/oligochaete
tissue,
D. lacteum
10
5
0
A
B
C
D
E
F
G
F
G
F
G
-5
-10
Dugesia spp.
10
5
0

Polycelis spp. : Lumbricus tissue.
A
B
C
D
E
-5
-10
Bait types:
A. - Lumbricus tissue,
B. - fresh Rutilus tissue,
C. - decomposing Rutilus tissue,
D. - chironomid/oligochaete tissue,
E. - fish viscera,
F.
- Potomogeton crispus,
G. - control (empty).
Polycelis spp.
10
5
0
A
-5
-10
B
C
D
E
Field Experiments
Feb. / Mar. / Apr.
species
Night #1
BT BT
2
1m
BT
G
BT BT
BT BT
BT
BT
Night #2
BT BT
2
1m
methods
baits
3
nights
months
BT
G
BT BT
BT BT
BT
BT
zones
Night #3
BT BT
2
1m
BT
G
BT BT
BT BT
BT
BT
Each method was compared to each other with
regard to quality and quantity of collected samples.
Bait Trap
Cheap and less labour intensive trapping method.
 Can be targeted to a particular group of animals.
 Easy to deploy in any aquatic habitat.
 Large area sampled (semi-quantitatively).

Bait holder
Funnelled
entrance
Standard Sampling Methods
1.
2.
1m2 quadrat, hand collection.
Van-Veen Grab (~0.2m2).
1 m2 grid
http://cramp.wcc.hawaii.edu/LT_Montoring_files/lt_Benthi
c_Monitoring.htm
Van-Veen grab
http://www.duncanandassociates.co.uk/equip.htm
Results
Qualitative


Abundant species were detected by all 3 sampling
methods.
Less abundant species e.g. D. lacteum were more difficult
to detect by standard methods.
Percentage D. lacteum detections
100%
80%
60%
40%
20%
0%
Van-Veen
1m2 quadrat
Bait trap
Results
Quantitative
Results of trap tests (N=81) in L. Mask
Bait type
Feb
C
Mar
Apr
Feb
D
Mar
Apr
Feb
A
Mar
Apr
Night
#1
#2
#3
#1
#2
#3
#1
#2
#3
#1
#2
#3
#1
#2
#3
#1
#2
#3
#1
#2
#3
#1
#2
#3
#1
#2
#3
18
22
19
19
15
10
10
9
15
2
0
5
4
1
1
4
3
0
12
0
3
6
9
7
10
12
2
D. lacteum
10
24
20
13
10
9
7
6
9
0
0
5
4
2
3
0
3
1
11
3
8
10
9
1
10
8
2
23
15
18
17
18
16
9
12
10
4
3
3
3
4
0
3
0
2
11
10
0
3
11
15
12
11
6
32
38
36
36
32
36
21
47
39
41
57
48
41
36
32
30
22
25
11
27
9
15
6
34
32
26
34
Dugesia ssp
16
33
19
40
34
37
18
32
33
39
40
32
45
50
21
37
28
20
31
6
8
31
10
15
12
16
25
37
21
28
32
37
21
15
41
34
37
40
45
36
47
39
29
31
33
39
23
38
26
36
33
25
13
13
26
31
40
27
36
38
36
36
35
20
49
34
48
34
21
31
46
46
42
53
39
52
41
35
40
27
46
3 monthly mean trap tests results
Polycelis ssp.
37
32
31
26
36
35
32
25
24
23
45
29
35
34
32
20
49
50
39
43
37
47
45
38
32
39
34
37
32
29
36
39
35
35
30
34
27
49
21
39
44
44
24
50
48
49
50
42
49
41
31
47
32
44
Bait type
D. lacteum
Dugesia ssp
Polycelis ssp.
C
14.19
31.30
32.96
D
2.22
36.33
36.74
A
7.48
22.00
41.26
Results
Quantitative - Lough Mask bait preferences
Lake trapping generally confirmed laboratory experiments results.
 Most effective baits for species were those indicated by laboratory
preferences.
 Highest trap selectivity observed for the least abundant
species (D. lacteum).

Dugesia spp.
D. lacteum
Polycelis spp.
45
45
45
40
40
40
35
35
35
30
30
30
25
25
25
20
20
20
15
15
15
10
10
10
5
5
5
0
0
0
C
D
A
C
D
A
C
D
A
Optimal trapping results
(only preferred baits for each species)
compared with results for standard methods
Polycelis spp.
Dugesia spp.
D. lacteum
60
60
50
50
20
40
40
15
30
30
10
20
20
5
10
10
30
25
0
Mean
Mean±SD
Mean±1.96*SD
0
0
Van Veen
Quadrat
Bait Trap
Van Veen
Quadrat
Bait Trap
Van Veen
Quadrat
Bait Trap
Means +- SD and ranges of numbers per sampling unit for 3 species and 3 methods.
(N.B. Different vertical scales).
Conclusions

Bait trapping is a non-intrusive and non-destructive sampling
method.

Bait traps can be set in a wide range of freshwater habitats.

Bait traps can be more cost effective and less labour intensive
than other methods.

Information on responses of target species to alternative baits
is required for optimal trapping

Bait trapping can be particularly effective for obtaining
samples of rare taxa.
References




Ball, I. R. and T. B. Reynoldson 1981. British Planarians.
Cambridge Univ. Press, London.
Maitland, P.S., 1977. A Coded Checklist of Animals occurring in
Fresh Water in the British Isles. Institute of Terrestrial Ecology.
Reynoldson, T.B. 1967. A key to the British species of
freshwater triclads. Sci. Publ. Freshw. Biol. Ass., 23, 1-28.
Western River Basin District Eel Management Plan, December
2008. The Department of Communications, Energy and Natural
Resources.