Summer 2010 collapse of the Lake
Nipissing zooplankton community
subsequent to the introduction of
the invasive zooplankter
Bythotrephes longimanus
Jean-Marc Filion
A Lake Nipissing Partners in Conservation case study
Correspondence address:
135 West Peninsula Rd, North Bay, ON P1B 8G4
lnpc.northbay@gmail.com
April 4, 2012
2010 – Sampling Stations – Lake Nipissing
Sturgeon Falls
North
Bay
S6
Goose
Is
S3
Manitou
Is
S8
S2
S4
S1
S5
French River
5 km
Callander
Bay
South Bay
Surface area 873 km 2
Average depth 4.5m
5% of all Ontario angling
Direction of travel
Horizontal strata sampling method
Float
Net
Weight
Net being hauled horizontally
150 m at a depth of 1 m
in this instance.
Depth data logger
inserted in net to
monitor depth of haul
Taking the animals
out of the net, and washing
them into a large, white,
plastic tub
Samples, once concentrated
with 80 micron filter
The Players
Bythotrephes longimanus
Adult
barb
barb
Time
barb
Juvenile
barb
barb
With each molt, an additional barb is added
Young
barb
Large transparent
predator – is
out-competed by
Bythotrephes longimanus
Geotrichia
Conochilus unicornis
Blue green algae Colonial rotifer
Lake herring (Cisco) (Coregonus artedi) - to 18 inches approximately
Yellow perch (Perca flavescens ) – to 12 inches approximately
Rainbow smelt (Osmerus mordax) – to 8 inches approximately
Yellow walleye
Stizostedion vitreum
This fish was
live-released
Results
2010 – Sampling Stations – Lake Nipissing
Sturgeon Falls
North
Bay
S6
Goose
Is
S3
Manitou
Is
S8
S2
S4
S1
S5
French River
5 km
South Bay
Callander
Bay
S8 - Bythotrephes longimanus average abundances
an./m3
120
113
103
100
83
80
60
42
39
40
20
14
10
9
3
11
14
3
0
30 May
7 Jun
13 Jun 20 Jun
27 Jun
6 Jul
2010
11 Jul
19 Jul
31 Jul
10 Aug 20 Aug 20 Sep
Bythotrephes longimanus abundances per stratum per date
an./m3
291
300
250
230
Station 8 - Lake Nipissing, 2010
200
140
150
110
100
73
75
55
53
50
23
17
7
4 2
15 14
3
3
13
30
22
19
6
5
4
11 11
1
11
36
11
5 2 6 3 7
16
0
1m
30 May
7 Jun
5m
13 Jun
20 Jun
27 Jun
6 July
11 July
10m
19 July
31 July
10 Aug
20 Aug
20 Sept
Bythotrephes eats zooplankton
So what is the zooplankton population
doing during this time?
Relative
scale
6
S8 - Zooplankton abundance per date per stratum
Zooplankton
mostly at d > 5m
(mainly Daphnia galeata mendotae)
2010
5
4
Zooplankton recovery
mostly at d > 5m
(mainly Copepods)
3
2
1
0
30 May
7 Jun
13 Jun
20 Jun
27 Jun
6 Jul
1m
11 Jul
5m
19 Jul
10m
31 Jul
10 Aug
20 Aug
20 Sep
Relative
scale
S8 - Zooplankton abundance (averaged over the strata )
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
30 May 7 Jun
13 Jun 20 Jun 27 Jun
6 Jul
2010
11 Jul
19 Jul
31 Jul 10 Aug 20 Aug 20 Sep
Large Daphnia galeata mendotae population
S8, May 30th, 2010 in the 5m stratum
Mostly
300 Bythotrephes
40 Bythotrephes
daphnia
10 Bythotrephes
Mostly
daphnia
100 Bythotrephes
3900 Bythotrephes
150 Bythotrephes
June 13
400 Bythotrephes
1000 Bythotrephes
170 Bythotrephes
Fewer
daphnia
June 20
720 Bythotrephes
1900 Bythotrephes
750 Bythotrephes
Zooplankton depleted in all strata
By the end of June, the spiny water flea had pretty well eliminated
most of the zooplankton in the water column
3100 Bythotrephes
990 Bythotrephes
480 Bythotrephes
1500
60
60
300
150 Bythos
70 Bythos
By July 11, 2010, Bythotrephes itself had crashed to much lower abundances.
Only small remnant zooplankton populations remain over much of the lake.
S8 Results
Come August some harvestable
walleye started consuming
Bythotrephes
Aug. 7, 2010 Kevin O'Grady captures a 35 cm walleye
with only Bythotrephes in its stomach.
Aug. 13, 2010 Stéfane Filion captures a 30 cm walleye
with only Bythotrephes in its stomach.
Food web implications
Energy flow
Before introduction of
Bythotrephes
walleye
perch
snails
herring
smelt
insect
larvae
copepods
minnows
cladocera
Food web implications
After introduction of
Bythotrephes
perch
Energy flow
walleye
smelt
herring
Bythotrephes
snails
insect
larvae
copepods
Cladocera
minnows
Lost
to
sediments
Nutrients
may recycle
in early fall
- wind /
shallow
depths
Food web implications
(before Bytho)
walleye
perch
zooplankton
phytoplankton
1 kg
10 kg
100 kg
1000 kg
Food web implications
(after Bytho – no collapse)
walleye
perch
Bytho
zooplankton
phytoplankton
0.1 kg
1 kg
10 kg
100 kg
1000 kg
Food web implications
(after Bytho – after collapse)
Energy flow constricted
walleye
0.001 kg = 1 g
perch
0.01 kg
Bytho 10 kg * 1/100
0.1 kg
zooplankton
100 kg
phytoplankton
1000 kg
Fisheries management implications
(present system)
Healthy walleye pop + Healthy ecosystem
Max. sustainable yield = 100,000 kg
Fisheries management implications
(present system)
Healthy walleye pop + Healthy ecosystem
Max. sustainable yield = 100,000 kg
Stressed walleye pop
(harvest set at 2/3 of m.s.y.) = 66,000 kg
Fisheries management implications
(present system)
Healthy walleye pop + Healthy ecosystem
Max. sustainable yield = 100,000 kg
Stressed walleye pop
(harvest set at 2/3 of m.s.y.) = 66,000 kg
NFN gets 2 fish for every 1 fish sport fishery
NFN harvest quota set at 44,000 kg
Sport fishery quota set at 22,000 kg
Fisheries management implications
(Energy flow restricted)
Healthy walleye pop + Unhealthy ecosystem
Max. sustainable yield = 50,000 kg (too high?)
Fisheries management implications
(Energy flow restricted)
Healthy walleye pop + Unhealthy ecosystem
Max. sustainable yield = 50,000 kg
Stressed walleye population
(harvest set at 2/3 of m.s.y.) = 33,000 kg
Fisheries management implications
(Energy flow restricted)
Healthy walleye pop + Unhealthy ecosystem
Max. sustainable yield = 50,000 kg
Stressed walleye population
(harvest set at 2/3 of m.s.y.) = 33,000 kg
NFN gets 2 fish for every 1 fish sport fishery
NFN harvest quota set at 22,000 kg
Sport fishery quota set at 11,000 kg
Fisheries management implications
(Energy flow restricted)
NFN gets 2 fish for every 1 fish sport fishery
NFN harvest quota 22,000 kg
Sport fishery quota 11,000 kg
2011 harvest results
NFN quota set at 40,000 kg or so
Caught 21,000 kg
Fisheries management implications
(Energy flow restricted)
Healthy walleye pop + Unhealthy ecosystem
Max. sustainable yield = 50,000 kg
Very stressed walleye population (large walleye?)
(harvest set at 1/3 of m.s.y.) = 17,000 kg ???
NFN gets 2 fish for every 1 fish sport fishery
NFN harvest quota set at 11,000 kg
Sport fishery quota set at 6,000 kg
(Just one of many management options)
Fisheries management going forward
•
•
•
•
•
We are at a critical point
Doing nothing is the worst option
We are out of time
Nobody wants the take the medicine
Need a plan and a way to sell it /implement it
Food web implications
A number of problems may arise from the introduction of Bythotrephes.
Bythotrephes invasion elevates trophic position of zooplankton
and fish: implications for contaminant biomagnification
Michael D. Rennie • Angela L. Strecker • Michelle E. Palmer
Biol Invasions (2011) 13:2621–2634
DOI 10.1007/s10530-011-0081-0
“We demonstrated that increases in trophic position of
the magnitude reported here can lead to substantial
increases in fish contaminant concentrations.”
Nineteen lakes studied, focused primarily on lake herring (Coregonus artedi)
Food web implications of the addition
of smelt to the ecosystem
Ecosystem effects of Rainbow Smelt (Osmerus mordax)
invasions in inland lakes: A literature review
Rebekah C. Rooney and Michael Paterson
Canadian Technical Report of Fisheries
and Aquatic Sciences 2845 (2009)
“Rainbow smelt invasion may affect the accumulation of
persistent lipophilic contaminants and heavy metals such as
mercury in top predators.”
Walleye in this range
must be released
Meals per month
Children (to age 15) and women of child bearing age
March 2011, MOE Guide to eating sport fish in Ontario. Consumption advice in the
tables is based on an average meal size of 227 grams for an average size adult
of 70 kilograms (154 pounds).
Want a copy of the full report?
Jean-Marc Filion
lnpc.northbay@gmail.com
Bow to
the queen !
S4 - Zooplankton community structure
Lake Nipissing Outlet – French River Headwaters
Sturgeon Falls
North
Bay
S6
Goose
Is
S3
Manitou
Is
S8
S2
S4
S1
S5
French River
5 km
South Bay
Callander
Bay
S4 – A biodiversity refuge
S4 is located in an area of crucial importance to Lake Nipissing as it serves as both a fish and
zooplankton refuge, thus helping to preserve biodiversity. It is near the outlet of Lake Nipissing,
which drains in a southwesterly direction via the French River. The bathymetry of this area is
unusual in that a cold water refuge is available due to the deeper waters available in this location.
The maximum depth that we were able to find using our Hummingbird depth sounder was 54m.
In the summer this area
becomes a cold water
refuge for the lake
herring (cisco) and the
smelt. Warmer waters
on top and oxygen
depletion at depth keep
the fish sandwiched
in a definite band, as
indicated by this picture
taken of our Hummingbird
sonar unit.
S4
Depths in metres
0.5 km
S4 - French River - D.O.(mg/L) - 2001
S4 - French River - Temp. (C) - 2001
Depth (m)
July
August
July
Depth(m)
August
0
0
20
9,0
5
5
8,8
10
22
10
8,0
7,0
6,0
15
18
15
7,0
5,0
20
20
20
4,0
25
18
16
16
25
14
30
12
30
6,0
10
3,0
35
14
35
8
12
40
4,0
2,0
3,0
45
1,0
10
8
40
6
45
6
New Players
Mysis relicta
Chaoborus
4 mm
S4 –Bythotrephes and
zooplankton abundances vs depth
Bythotrephes
abundance
(an/m3)
30
Zooplankton
abundance
(Relative scale max is 6)
6
28.7
Fish zone
25
5
July 10, 2010
21.3
Something interesting
may be going on at
these depths
20
Bythotrephes
15
4
3
Zooplankton
10
2
7.0
4.1
5
2.3
2.7
1
1.8
1.6
0.4
0.2
0
0
1
5
10
15
18
23
28
31
34
Depth (m)
Bythotrephes abundances correlate negatively with depth
38
Relative abundance
30.0
S4 - Relative abundances of Copepod taxa vs depth
25.0
Copepod abundances correlate positively with depth
20.0
15.0
Something interesting
may be occurring
at these depths
10.0
Fish zone
5.0
0.0
1
5
Diaptomus
10
15
Cyclops
18
23
28
Depth (m)
Epischura lacustris
31
34
Senecella calanoides
38
S4 - Relative abundances of selected Cladocera taxa vs depth
Mostly D. pulicaria
25.0
Relative scale (max is 30)
20.0
15.0
10.0
Something interesting
may be occurring at
these depths
Diaphanasoma birgei
only collected in trace
amounts and only
in the 1m stratum
2000/2001 sampling indicates
that a 9-spine stickleback
population exists at depth
at S4 – exactly at what depth
is not known at this time.
Fish zone
5.0
0.0
1
5
10
15
18
23
28
31
Depth (m)
Daphnia
Bosmina
Eurycercus
Latona setifera
34
38
Relative scale
(max is 30)
S4 - Relative abundances of Conochilus,
Geotrichia and Ostracoda taxa vs depth
12.0
10.0
8.0
June 10, 2010
6.0
4.0
2.0
0.0
1
5
10
15
Conochilus
18
23
Depth (m)
Geotrichia
28
Ostracoda
31
34
38
S1 - Zooplankton community structure
Callander Bay
Sturgeon Falls
North
Bay
S6
Goose
Is
S3
Manitou
Is
S8
S2
S4
S1
S5
French River
5 km
South Bay
Callander
Bay
Callander Bay
S1
0.5 km
S1 - Callander Bay
Bythotrephes abundance by date & by stratum
an./m3
9.11
10.00
5.48
5.0
3.8
5.00
0.96
0.4
0.00
July 7
Aug 1
1m
5m
8m
140
S1- Leptodora kindtii
an./m3
In 2000/2001 Leptodora was quite
abundant reaching abundances of
over 100 an./m3 in mid-August. In
2010, Leptodora is only present in
trace amounts in early July, and is
not collected Aug. 1st.
- mouth area
of 0.5 m2 – 300
micron Nitex mesh.
14
1.4
0.14
S1 - 2001
Relative scale
30
25
20
S1 - Leptodora abundance
15
10
5
0.4
0.4
0.6
S1 - 2010
0
Jul 7
Aug 1
1m
5m
8m
S1- Diaptomids
By the end of the 1st week of July
Bythotrephes had driven Diaptomids
at S1 to trace amounts. Historicaly
abundances at this time were in the
15000 an./m3 range. By the 1st of
August the Diaptomids are
recovering somewhat.
Relative scale
30
25
20
S1 - Diaptomus abundance
S1 - 2010
12.5
15
7.5
6
10
5
0.1
0.3
0.6
0
Jul 7
Aug 1
1m
5m
8m
S1- Cyclops
By the end of the 1st week of July
Bythotrephes had driven Cyclops at
S1 to trace amounts. Historically
abundances at this time were in the
20000 to 40000 an./m3 range. By
the 1st of August the Cyclops are
recovering somewhat.
Relative scale
30
24
S1 - Cyclops abundance
25
S1 - 2010
20
12.5
15
7.5
10
0.4
5
0
Jul 7
Aug 1
1m
5m
8m
S1- Daphnia
By the end of the 1st week of July
Bythotrephes had driven Daphnia at S1
to trace amounts. Historically abundances
at this time were variable but typically in
the 5000 an./m3 range. In 2010, by the
1st of August Daphnia were very
abundant at depth. In 2001 only D.
retrocurva was collected at S1. In 2010
only one D. retrocurva individual was
collected, the rest being Daphnia galeata
mendotae.
Relative scale
30
30
S1 - Daphnia abundance
S1 - 2010
25
1m
20
5m
15
8m
5
10
5
0.3
0.3
4.5
0.4
0
Jul 7
Aug 1
S1- Bosmina sp.
By the end of the first week of July 2010,
Bythotrephes had pretty well eliminated
the Bosmina sp. from Callander Bay. They
remain absent from the collections on
Aug. 1st. In 2000/2001 their average
abundances come July were in the 5000
to 20000 an./m3 range. The ‘U’ shaped
curve from 2001 may imply that Bosmina
may serve as a food source for juvenile
and larval fish who move on to other prey
as they reach a larger size.
Relative scale
S1 - Bosmina abundance
30
25
S1 - 2010
20
15
10
0.1
5
0
Jul 7
Aug 1
1m
5m
8m
S1- Diaphanasoma birgei
Historically Diaphanasoma at S1 was a highly
variable species, sometimes attaining
abundances as high as 40000 an./m3, only to
almost disappear from the collections the week
after. Collections in 2000/01 were made using
vertical hauls. This may imply horizontal
patchiness. Populations were usually small at
the beginning of July, but then increased to an
average of 10000 an./m3 come the first of
August. In 2010, Diaphanasoma was not
collected on July 7th, 2010 and showed little
sign of becoming abundant on the 1st of
August. It was absent from the collections at
the 8m stratum. Bythotrephes may be keeping
this species at low abundance levels at S1.
Relative scale
30
S1 - 2010
S1 - Diaphanasoma abundance
1m
20
5m
10
2.5
1.5
0
Jul 7
Aug 1
8m
S1 – Holopedium gibberum
S1 was sampled July 7th and August 1st, 2010. Holopedium gibberum was only
collected in trace amounts from the 5m stratum on July 7th. Historically,
Holopedium had average abundances of around 100 an./m3 in early July and early
August. It would seem that Holopedium disappears quicker and attains lower
maximum abundances since the introduction of Bythotrephes.
S1 - Conochilus unicornis abundance
Relative scale
30
1m
5m
8m
25
20
10
15
10
7.5
0.2
0.1
5
0
Jul 7
Aug 1
S1 - Geotrichia abundance
Relative scale
30
1m
5m
8m
25
20
10
15
4.5
10
5
0.1
0.2
0
Jul 7
Aug 1
Conochilus unicornis and Geotrichia, not collected in any important amount in 2000/01
is now becoming common to moderately abundant as summer progresses at S1.
In the winter perch turn to eating
snails and mayfly naiads. They could
do the same in the summer.