Do Geomorphic Units Influence Brown Trout Size? Introduction




Дата канвертавання26.04.2016
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Total Grade: 8/10Andrew Badje

Ecology of Fishes: 511

Research Paper Outline

4/10/07
Do Geomorphic Units Influence Brown Trout Size?


Introduction:

Brown Trout Overview Good: Get citations for this stuff and you’re gold.



  • Freshwater fish of streams and rivers

  • Migrate from lakes into rivers and streams to spawn

  • Native to Europe and Asia, but found all over world

  • Prefer cold, well oxygenated waters and rock cover, overhanging vegetation, and undercut banks

  • Feed upon invertebrates, small fish, frogs, and insects

  • Can grow up to 20 kg (40 lbs), but in smaller streams usually weigh around 1 kg (2 lbs), and get up to 18.0-54.5 cm in fork length

  • Targeted for recreational fly fishing and are a preferred food fish

Ecological Mechanism Influencing Brown Trout in Black Earth Creek

  • Geomorphic Units are presumed to influence the trout’s location

  • Runs, Riffles, and Pools each have different qualities among each of them and could be preferred from one over another

  • Different qualities include water flow velocity and water depth, as well as trout size in each geomorphic unit may lead to intraspecific competition Trout size thought not clear.

Goal/ Goals of the Research Paper

  • Null Hypothesis = Geomorphic Units aren’t different enough to allow for Brown Trout selection

  • Alternative Hypothesis = Geomorphic Units are different and Brown Trout allocate to different geomorphic units

  • Glad to see you understand how to think about this statistically. For your paper, however, it suffices to say that you believe that brown trout size and population densities will vary between geomorphic units.

  • Are larger Brown Trout found in Pools as opposed to Riffles or Runs? Reason to think this? Citation?

  • Where are Brown Trout densities the highest in the three geomorphic units?

  • Does water flow velocity influence what Brown Trout sizes prefer certain geomorphic units?

  • Does water depth influence why certain Brown Trout sizes allocate to certain geomorphic units?

  • Do smaller Brown Trout prefer Riffles and Runs as opposed to Pools?

  • I’d say pick a theme and go with it. If you are more interested in geomorphic unit (and it looks like you are) don’t worry so much about depth and flow velocity. You could analyze the data in terms of geomorphic unit and then analyze geomorphic unit in terms of depth and velocity so that you can interpret your results (i.e. we found more trout in pools, pools tended to be deeper and slower, thus we interpret our result to mean that trout like deeper slower water)


Methods: (-0.5 points. Incomplete description of sample method)

Field data collection



  • What about setting up 5m transects? Timing the run of the electrofishing unit?

  • Electro-fishing used in 14 different sections of Black Earth Creek and Salmo Pond (Riffles, Runs, and Pools)

  • Electric impulses paralyze fish for a few seconds to be vulnerable to be netted

  • Students netted all fish in each section that could be caught and were bucketed and later classified by species, weighed, and measured for length

  • One student went into the middle a geomorphic unit and took one measurement per geomorphic unit (14 total) (can’t think of tool name?) Refering to flow velocity? Took between 1 and 3 measurements of flow velocity / geomorphic unit. Equipment: Swoffer Flow Meter. Unless you’re talking about conductivity and temperature. This was a conductivity meter.

  • Depth taken at left, middle, and right sections of every five meters of creek

Data analysis Word it as “used analysis of variance to analyse whatever” not “One graph of whatever”

  • Six total graphs made Don’t need to count figures

  • One of total Brown Trout caught per geomorphic unit use BT/m2 or something similar to eliminate size of reach as a variable.

  • One of Brown Trout sizes caught in the geomorphic units (ANOVA included)

  • Two of Brown Trout sizes caught in the geomorphic units ( one of all Brown Trout 160 mm and under, the other 161 mm and above) (no ANOVA used because each graph is a split of the Brown Trout size vs. Geomorphic unit graph)

  • One of Water Flow Velocities per geomorphic unit (ANOVA included)

  • One of Water Depths per geomorphic unit (ANOVA included)

  • ANOVA analysis used because testing more than 2 categorical variables


ResearchResults: General: Graphs should have no grey background. Gridlines optional. No anova tables, just p-values and means. -0.5 point for including graphs that make no clear point. -0.5 point for including ANOVA tables uncessarily. -0.5 point for not stating p-values and means.

  • More Brown Trout caught in Riffles and Runs

  • Overall, Brown Trout were larger in Pools, some larger fish caught in Riffles

  • Brown Trout Size vs. Geomorphic Unit ANOVA test rejects Null Hypothesis

  • Much more Brown Trout under 160 mm caught in Riffles and Runs

  • Water Velocity ANOVA test and graph accepts that water velocities for each geomorphic unit are all dynamic and near the same (Run velocities are a little higher)

  • The Water Depth graph show that on average Pools are deepest, then Runs, then Riffles, and the ANOVA test shows that they are significantly different


Figure 1: Run and riffle catch numbers were much higher than pool catch numbers again, use BT/m2. Include a p-value.



Figure 2: Brown Trout size numbers even throughout, but pool averages were higher. *Bottom pool number was a 30 mm Brown Trout Fry, the rest were all adults/ juveniles. Could justify removing the 30 mm Brown Trout Fry b/c its from that “pool” that isn’t really part of the creek (in other words, its not like the other pools. Toss it. ) Also, consider a boxplot or somehow indicating the mean size on this graph.





Anova: Single Factor





































SUMMARY



















Groups

Count

Sum

Average

Variance







Pool

24

5320

221.6667

6970.58







Riffle

98

14459

147.5408

4770.828







Run

118

21412

181.4576

6179.823

















































ANOVA



















Source of Variation

SS

df

MS

F

P-value

F crit

Between Groups

128353

2

64176.52

11.29891

2.06E-05

3.03392

Within Groups

1346133

237

5679.886































Total

1474486

239

 

 

 

 






















Table 1: ANOVA test for Brown Trout sizes per Geomorphic unit Don’t include this output table in the report. We need you to give us the important numbers (i.e. means, p-value). You should report the average sizes (221.7, 146.5, and 181.5) etc.

Figure 3: Same points for Brown Trout Size per Geomorphic unit, but for Brown Trout 160 mm and under. Less fish caught in pool geomorphic unit. What is the point of this figure? The only new thing I get from it is that there are few small fish in pools. If that’s all you want to do, present it in text or in table (Morphic unit vs. # BT/m2 under 160mm)


Figure 4: Same points for Brown Trout Size per Geomorphic unit, but for Brown Trout above 160 mm. Riffles had the highest trout sizes, and runs and riffles had a higher number of larger trout. But earlier you said that pools had larger trout (see figure 2 legend box) Which is it? And Why do you break up trout at 160mm? seems arbitrary . Finally, 3 graphs of BT size vs. morphic unit seems a bit overkill, unless there is a specific point. I don’t see this point.



Figure 5: Flow velocity versus Geomorphic unit. Pool velocities are generally lower, while riffle and run velocities were higher. You can’t say this. Report your p-value (the anova table). Is a p-value of 0.689 significant? Not even close. Also, its confusing to have the order of variables change (in your other graphs, they go run, riffle, pool). Make the legend the same for each unit in every graph.




Anova: Single Factor





































SUMMARY



















Groups

Count

Sum

Average

Variance







Run

5

5.261245

1.052249

0.404753







Riffle

5

4.663877

0.932775

0.827316







Pool

3

1.78

0.593333

0.152933

















































ANOVA



















Source of Variation

SS

df

MS

F

P-value

F crit

Between Groups

0.403401

2

0.201701

0.385356

0.689887

4.102821

Within Groups

5.234142

10

0.523414































Total

5.637543

12

 

 

 

 

Table 2: ANOVA test for Water Flow Velocity versus Geomorphic Unit. Shows little to no difference between all three geomorphic units.

Table 6: Water Depths versus Geomorphic Units. Pool was generally the deepest followed by runs, then riffles. Good. Pvalue still.




Anova: Single Factor








































SUMMARY



















Groups

Count

Sum

Average

Variance







Pool

45

3345.5

74.34444

380.2934







Riffle

108

3026

28.01852

134.3735







Run

99

4448

44.92929

244.0664

















































ANOVA



















Source of Variation

SS

df

MS

F

P-value

F crit

Between Groups

68818.79

2

34409.4

155.6975

1.38E-44

3.032065

Within Groups

55029.38

249

221.0015































Total

123848.2

251

 

 

 

 

Table 3: ANOVA test for Water Depth versus Geomorphic Units. Shows that each Geomorphic Units Water Depth is significantly different.

Discussion:

  • Higher average of trout sizes were found in pools which may be due to more vegetation, a lower water velocity, or deeper water depths.
    Didn’t match null hypothesis, geomorphic units were too different and did allow for different Brown Trout allocation by size preferential. Reject null hypothesis. Evidence supports your hypothesis that trout allocate habitat based on fish size.

  • Zimmer and Power state that all river habitats are used to some degree, which shows why Brown Trout were highly abundant in all three geomorphic units.

  • Smaller trout (more) were caught in riffles and runs than pools, maybe due to more intraspecific competition, able to expend less energy with less water flow friction, able to hide easier from predation.

  • Heggenes shows that larger trout prefer deeper streams, while smaller ones prefer riffles and runs. This is equivalent to what was found among the data of Black Earth Creek and Salmo Pond.

  • Water Flow Velocity shows little variation among geomorphic units, all highly differential. Possibly due to the Black Earth Creek and Salmo Pond being fairly different creeks and showing different water velocities among the same geomorphic units.

  • Heggenes also states that all trout seek out areas with lower water flow velocities to minimize energy expenditure from friction. (Problem might be that there aren’t enough water velocity values to show if they were different from one another?)

  • Water Depth found to be deeper in pools. The deeper the section of stream shows that there are less small trout there.

  • Myrvold says depth is the most controlling factor for juvenile brown trout density.

  • Reiser- velocity matters more over depth with Brown Trout.

  • (Velocity data less valid in this situation because not enough data to show any differences)

  • Witzel and MacCrimmon- Brown trout utilize faster water velocities and coarser substrates that minimized species interactions during spawning

- May show why some Brown Trout numbers are higher in Riffles and Runs, which showed to have an overall higher water velocity than Pools and that species in riffles and runs go there for less intraspecific and interspecific interactions.


Works Cited

Heggenes, J. 1988. Physical Habitat Selection by Brown Trout (Salmo trutta) in Riverine Systems. Nordic Journal of Freshwater Research. 64: 74-90.

Myrvold, K.M. 2006. Relationships Between Juvenile Brown Trout (Salmo trutta) Densities, Their In-Stream Habitat, and Riparian and Watershed Characteristics in Tributary Streams of the Numedalslagen River, Norway. Norwegian University of Life Sciences, Department of Ecology and Natural Resources. 1-45.

Reiser, D.W. 1976. Determination of Physical and Hydraulic Preferences of Brown and Brook Trout in the Selection of Spawning Locations. Water Resources Research Institute. 29: 1-112.

Witzel, L.D. and H.R. MacCrimmon 1983. Redd-Site Selection by Brook Trout and Brown Trout in Southwestern Ontario Streams. Transactions of the American Fisheries Society. 112: 760-771.

Zimmer, M.P. and M. Power 2006. Brown Trout Spawning Habitat Selection Preferences and Redd Characteristics in the Credit River, Ontario. Journal of Fish Biology. 68: i-xxviii.


You have 2 papers that deal specifically with BT spawning habitat, but not much in the discussion about it.


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