Observations on the dispersal patterns of Catostomus
commersoni in Black Earth Creek, WI
OK, so I know that back in the day you might be able to pull
off a title like that but, I think you should shoot for something
more specific, perhaps: Determining stream habitat
preferences for white sucker, Catostomus commersoni, in
Black Earth Creek
Or…. in a central Wisconsin stream.
Abstract
[Need a sentence that says physical attributes of a stream influence the presnence
absence of
Data regarding the distribution of the white sucker were analyzed to look for patterns in
habitat type selected; to determine what factors are important in the fishes stream reach
use. Primary habitat was predicted to consist of deep, slow moving pools that contain fine
particled bottom substrate. Results show that white suckers density is positively related
do indeed select deep, slow moving water for habitation but favored substrate was found
to be gravel instead of silt. The analysis suggests the types of habitat white suckers in
other streams are likely to use and what morphological and behavioral traits cause
habitation of said reaches.[good this is a conclusion sentence, but it could be worded
better. "Our results can be used to categorize what stream habitat types favor high sucker
abundance…..and so on".]
Introduction
The white sucker, Catostomus commersoni common to streams, rivers and lakes
over most of North America. It is a benthivore that feeds on mollusks, insect larvae and
other invertebrates on the stream bottom (Saint-Jacques, 2000). Because of its dietary
preferences, it is morphologically adapted to be an efficient benthic feeder exhibiting a
subterminal mouth and papillate lips. Because of these adaptations, the white sucker is an
effective stream competitor and able to exist and reproduce in a wide range of habitats
(Saint-Jacques, 2000). Though a habitat generalist, the White sucker must have some
patterns to its distribution in the stream.
I know there is more on suckers, make the first paragraph general about their
biology and their role in streams, then the second paragraph should be more specific,
what other studies have shown for depth and substrate and velocity.
Because of its morphological adaptations and prey preferences; I expect white
sucker abundance will be positively related to depth and negatively related to water
velocity.. The reason for this is that the finer substrates are easier foraged over than an
area of cobble or boulders and benthic communities have greater abundance in slower
flow areas (Jowett, 1991) [ This is discussion, don't put this here! Wait and use it later]
Methods
The sampling area was a stretch of Black Earth Creek approximately 200 meters
long located just behind Salmo pond, between Cross Plains and Black Earth. The stream
is spring fed and thus considered a coldwater stream (mean temp. 3.5°C) and contains a
heterogeneous habitat with fast moving, rocky riffles and deep slow moving pools. The
study reach was divided into seven sampling sections based on hydrogeomorphic class. ..
Electrofishing
Block nets were set at the ends of sections to keep fish from moving out of…….
[See general comments] All fish were identified to species and had total length measured
(mm).. Fish were released back into the section their respective stream section.
Habitat data
Stream habitat data was collected following the electrofishing sampling. Each transect
was flagged in 5 meter intervals and the stream width and depth of each side were
recorded at each interval. Due to instrument error the water velocity was measured by
timing a floating object as it traveled a measured distance within the stream thalweg.
Dominant substrate was categorized as silt, gravel, cobble or boulders For each transect.
The other variables recorded were, dominant riparian vegetation, Mean buffer width,
undercut bank length and temperature.
Results So I see no analysis for lengths, I think you should explore this. Add a study
question about how you think a stream physical habitat characteristic will influence
sucker lengths.
White suckers were collected in five of the seven reaches sampled, a total catch of
113. The distribution of the suckers was not equal among the five reaches producing
positive catches[what is a positive catch?]. The max number of white suckers caught was
54 in reach three and the minimum was three in reach seven. The two reaches that did not
produce any fish were two and six {so what}. The average length of sucker caught was
156.4mm and the longest individual was 451mm. The habitat and fish data show some
trends about the preferences in microhabitat selection favored by white suckers in the
sample stream.[ some trends huh?, delete this, the results need to be crisp, no extra words,
don't worry if it is short]
Depth
The mean depth of the entire study area was 56.9 cm, with a maximum in reach 1
of 100cm and a minimum in reach 6 of 10cm. The mean depth of the pool reaches 1 and
3 was 78.4cm. The run and riffle reaches had mean depths of 57.3cm and 34.5cm
respectively. The number of white suckers caught related to reach mean depth is positive
and roughly linear (fig.1). The reach that produced the most suckers had a mean depth of
76.4 cm and the reach
Fig.1 The number of suckers caught in
each reach by depth (cm)
that produced the
White sucker frequency vs. Mean depth
Number of suckers caught
60
lowest number of
R2 = 0.4968
50
suckers had a mean
40
30
depth of 31cm. It is
20
clear that as the
10
reaches increase in
0
20
30
40
50
60
Depth (cm)
70
80
90
depth, the number of
fish caught also increases. There were however two reaches that produced catches that
differed from this trend. In reach 2 (mean depth 64.8cm) there were no white suckers
caught and also in reach 7 (mean depth 49cm) there were only three suckers caught.
Because those two reaches did not follow the trend of the rest of the data, it is likely that
depth is not the only deciding factor in white sucker stream distribution.
Substrate
The substrate in the stream was judged at each transect by the size of the majority
of bottom material. The one that held the most number of transects was then considered
the dominant substrate for the reach. Cobble was the dominant substrate in reaches 1, 5
and 7. Gravel was dominant in 2, 3 and 5 while silt was dominant in 4. Boulders were the
dominant substrate in reach 6. The distribution of suckers caught (fig.2) shows a clear
Catch Frequency by Dominant Substrate
Gravel, 73
Cobble, 40
Fig.2 The number of white suckers
caught in each type of dominant
substrate
Silt, 19
Boulder, 0
preference for gravel (73 caught) followed by cobble (40 caught). Suckers were caught
less frequently over silt (19) and none at all were caught in reaches dominated by
boulders. The role of substrate is certainly important in the distribution of white suckers
though it does not follow the prediction that they prefer the finest substrate available. The
role of gravel as a bottom component is clearly a deciding factor in the habitat selection
process.
Hydrogeomorphic class
The relationship between hydrogeomorphic class and white sucker distribution is
definitely not something the fish takes into account when selecting its habitat; fish do not
know the difference between a run and a riffle section and would not use that as a reason
for or against habitation. However, it is useful to examine which reaches fish were caught
in (fig.3) because the hydrogeomorphic class gives a good overall picture as to the
general conditions of the reach. Pools held the most fish (82), runs the second most (22)
and riffle reaches were the least likely to hold suckers (9). The pool reaches also had the
most depth and were
Catch Frequency by Hydrogeomorphic
Class
Riffle, 9
less likely to contain
boulders and cobble
Run, 22
as the dominant
substrate. Riffles were
the shallowest and
Fig. 3 Sucker catch was higher
in pools than in riffles.
Pool, 82
had the largest
dominant substrate. The association of white suckers to hydrogeomorphic classification
of the reach, though not a factor in selection by the fish serves to support the prediction
that the fish distribute more to deeper reaches of the stream.
Flow velocity
The flow velocity was measured for each reach in the stream and the resultant
data show a clear affinity for slower moving water (fig.4). The flow velocity ranged from
Catch frequency by flow velocity
LOW (0-.25)
63
Fig.4 Sucker catch numbers
were highest in reaches with
low flow velocities.
INT (.25-.60)
47
HIGH (>.60)
3
0.21m/s in reach 5 to 1.1m/s in reach 6. The reaches were lumped into categories based
on flow, Low flow (0-.25m/s), intermediate flow (.25-.60m/s) and high flow (>.60m/s).
The most fish were caught in reaches in the low category (63). The next highest catch
rate was in the intermediate category (47) and only 3 were caught in the fast flow
category.The fact that the majority of fish caught came from reaches that experience low
flow rates supports the prediction that flow velocity is a factor in the dispersal patterns of
the white sucker in Black Earth Creek.
Discussion
There are certainly many complex and little understood factors that cause a stream
fish to choose which microhabitat it uses in a stream, many of which are impossible to
measure. However the data collected on white suckers in Black Earth Creek demonstrates
that depth, bottom substrate and flow velocity are heavily relied upon by the fish to
determine what part of the habitat it uses. These data can be used to illuminate what a
stream needs to have to support large populations of white suckers. It needs to have
relatively deep pools with a predominantly gravel substrate and must also contain areas
where the flow velocity is less than .60m/s.
There are several reasons for the white sucker’s affinity for deep, slower moving
reaches. Small benthic organisms constitute the majority of its diet; the majority of the
benthic invertebrates in a stream reside in areas of slow to intermediate flow (Jowett,
1991). Substrate also determines where the highest concentrations of prey species are
found. Though I predicted the sucker would prefer silty areas due to their high prey
content, the highest concentrations of benthic organisms are in areas containing mostly
gravel bottoms (Jowett, 1991). The results are supportive of prey density being an
important factor in habitat selection.
Because of its prey preferences and morphology, the white sucker can generally
be grouped into a guild of pool-selected species (Vadas, 2000). These are fishes that
spend the majority of their time in pool reaches of streams. The energy costs that go
along with maintaining position in faster moving water is one of the main reasons suckers
distribute more frequently in pools than other reaches. In fact, many stream fishes use
deep pool/run complexes at least some part of the day to avoid the energetic costs of
swimming (Webb, 2006). The reduced energy cost and pool-selected morphology are
also certainly factors that cause the sucker to choose a predominantly pool based habitat.
Predation is certainly a factor in any fishes habitat use, there are different results
in the presence or absence of predators. In a study done on a creek in Illinois, the
presence of large piscivores caused adult white suckers to shift their dispersal to
shallower runs and riffle reaches which the control group in the absence of predators did
not use (Schlosser, 1987). This suggests that predation is a large enough factor to cause
an entire habitat use shift even as the only experimental treatment. It also suggests that
the test area on Black Earth Creek does not contain significant predators of adult white
suckers.
[ your original title was too broad, you don't have any data to talk about spawning,
photoperiod, etc. Sure you know something about biology of suckers, but you don't have
the data therefore you must limit a paper to what you have. Now if you talk about these
factors in how you might design a more comprehensive study…then that is ok and worth
while!
Conclusion
The prediction that depth, dominant substrate and flow velocity are significant
factors in the dispersal of white suckers in Black Earth Creek was supported by the data
collected. It should be said however, that they are not the only parameters involved;
predation, reproductive cycle and weather are also some of the many factors in the
process of habitat selection by white suckers in stream habitats.
Sources
1. Jowett I, Richardson J, Biggs B, Hickey C, Quinn J, 1991. Microhabitat
Preferences of Benthic Invertebrates and the Development of a Generalised
Deleatidium spp. Habitat Suitability Curves, Applied to Four New Zealand Rivers.
New Zealand J. Marine and Fisheries Res. 25 187-199
2. Saint-Jacques N, Harvey H, Jackson D, 2000. Selective Foraging in the White
Sucker. Can. J. Zool. 78 1320-1331
3. Schlosser I, 1987. The Role of Predation in Age- and Size-Related Habitat Use by
Stream Fishes. Ecology 68 651-659
4. Vadas R, Orth D, 2000. Habitat Use of Fish Communities in a Virginia Stream.
Environmental Biology of Fishes 59 263-269