A power point presentation conveying the main points of my final year dissertation.

1. The story of my dissertation......
‘The role of mobility in community response to abiotic disturbance’
With a growing interest in ecology I decided to base my dissertation on
a recurring theme presented in my lectures and the literature; the
modification of ecosystems and communities resulting from
anthropogenic impacts such as urbanisation and climate change. With
this in mind and considering the resources and opportunities available to
me, I decided to test how these pressures could affect benthic
invertebrates in an urban river in the nearby River Cole, Birmingham.

2. Aims and objectives
Climate change and urbanisation is generally expected to create an
increase in flooding events thus, the main aim of my dissertation was to
determine the potential impacts of increased flooding on the benthic
community.
In my investigation I also attempted to explain the community reaction to the
disturbance. I carried out a study into the drift ability of the organisms. This led
me to outline two main objectives;
1. To determine the community response to pulse and press disturbances
2. To measure the importance of mobility in an organisms resistance and
resilience

3. The River Cole, Birmingham
Figure 1. A bird’s eye view of the study area. The blue line shows the course of the River Cole.
Source Google Earth (‘Eye altitude’ 1.70km)
I carried out my investigation on a 2.2km stretch of the Cole between
Moseley and Hall Green as it passes Sarehole Mill - SP099818 (see figure 1). It
was ideal to test potential impacts of urbanisation as it was not significantly
affected by its residential surroundings (compared to nearby rivers).

4. My methods ....
Objective One
Over the course of four weeks, my investigation
concentrated on two types of disturbance:
1. A pulse disturbance. To investigate the effects of
a pulse disturbance, the results from the first week of
sampling were compared to a control sample to
gauge the resistance of the benthos.
2. A press disturbance. To test the resilience of the
benthos, the control samples were compared to the
data from three subsequent weeks of regular
Plate 1. A surber sampler was used in
the systematic sampling of disturbances.
macroinvertebrates.
Source Author. Samples were taken (see plate 1) before a
disturbance was mimicked by intensive kicking up
of gravel and stones on the river bed for
approximately 5 minutes.

5. Objective two
A drift study was carried
out to independently
gauge the drift ability of
each organism to see if it
correlated with their
resistance/resilience at a
statistically significant level.
Plate 2. Collecting samples from a drift net. Source Author.
Three drift nets were placed side by side, downstream of an eight metre stretch of riffle.
The bed was then disturbed at different distances from the nets; 0.5, 1, 2, 4 and 8
metres. Between each disturbance the nets were removed and the samples were
collected. This was carried out late in the evening as it is thought that organisms drift
more during the night (see plate 2).
The theory behind this method was that those organisms found in the 8 metre samples
would have a higher propensity to drift than those in the smaller distances.

6. IN THE LAB ....
The samples I collected contained
a large amount of organic matter
(can be seen in plates 3&4) thus
sorting through them was an
important process to ensure that
all macroinvertebrates were
collected.
Plate 3. My station in the lab as I sieved my samples and
extracted the macroinvertebrates. Source Author.
Plate 4. The view through the magnifying glass as I sorted
through the organic matter in my samples. Source Author.

7. The initial sorting process was a long one and I couldn’t complete it on time within
lab hours so I set up a station to work from at home (see plate 5). Once all the
samples had been sorted and I had all the macroinvertebrates in test tubes with
IMS I began the process of identification.
Plate 5. My makeshift laboratory. Source Author.

8. Statistical analysis
All statistical analysis of my data looked exclusively at core taxa (those who
make up more than 1% of the total abundance of the control samples) who
appeared in all treatments; resistance, resilience and the drift study.
To measure ... I used a ...
Resistance Students t test
Resilience Wilcoxon rank sum test
Drift A two tailed Pearson correlation coefficient
I used the slope number from a regression line as a quantitative indicator of
an invertebrates’ ability to drift. A Spearman’s rank correlation coefficient
then gave the statistical significance of the relationship between drift and
resistance/resilience.

9. My findings...
I found that the benthic community in the River Cole is both resistant and resilient
to pulse disturbances thus the community composition is unlikely to change in light
of predictions of future climate change or the growing demands of urbanisation.
I was however, unable to provide sound evidence to explain this response. My
data did not indicate a correlation between mobility and an organisms resistance
and resilience. In fact, an organisms traits did not seem to explain most of my
findings. Instead my data suggested some interesting ideas:
- The removal of a food supply during a disturbance was a common factor that
affected abundance.
- The use of a hyporheic zone was evident however its presence was not
considered in my methodology.
- The resilience of Chironomidae was not only attributed to its traits but also to
the decreasing abundances of its crustacean predators.

10. This picture was taken on the hand in day just before I submitted it to the school office -
tired and relieved. I’ve been proud of my work ever since... even before I knew that I had
been awarded a first for it!
I learnt a lot in a relatively short amount of time and looking back, I enjoyed it ... I’d do it
all again!