1. Fish Communities Before and After a Bleaching Event
The goal of this project was to assess how fish communities in Northeast Oahu may have been affected by the mass bleaching event by examining abundance data from immediately before (2013) and after (2016).
I hypothesize that fish abundances will have declined from the to the surveys.
Kelsey Doughten

2. Data Description
Data files: projectMM.wk1 (main) and projectSM.wk1 (second)
28 samples and 47 species
Samples are coral reef surveys, species are fish counts
Environmental variables are:
Time (year: 2013 and 2016)
Depth (zone: shallow, mid, deep)
Hard coral cover (percent)

3. Data Processing Skewness: Outliers (2 SD cutoff):
Species data: Avg. = 2.0 (1.0 < skew < 4.2)
Environmental data: Avg. = 0.2 (0.0 < skew < 0.4)
Outliers (2 SD cutoff):
Samples: s1 (+2.66 SD)
Species: PSCE (+2.49 SD), PARR (+2.22 SD), and PSEV (+2.17 SD)
After log(x+1) transformation and general relativization:
Skewness: Avg. = 1.0 (-0.7 < skew < 3.0)
One sample was discarded: s1 (+2.92 SD)
Two species were discarded: PSEV (+2.55 SD) & PSCE (+2.17 SD)
27 samples and 45 species

4. Data Analysis

5. Results Conclusion: 3-dimensional solution
Criterion 1: decline in stress with added axis at least 5
Criterion 2: p value < 0.05

6. Results

7. Results Coefficient of determination (% variance explained by axes)
Orthogonality (independence of the axes)

8. Results

9. Results 2016 2013 ACNR CAGA CEPO CHHA CIFA PAFO THBA ACOL CAJA SUBU
ACLE
CHSO
CTST
PLIM
OXBI
SUFR

10. Results
Axis 1:
Positive: OXBI (τ = 0.677) and SUFR (τ = 0.536)
 Secondary consumers
Negative: ACLE (τ = ), CHSO (τ = ), CTST (τ = 0.540)
 Primary consumers
Axis 2:
Positive: ACNR (τ = 0.487), CAGA (τ = 0.488), CEPO (τ = 0.574), CHHA (τ = 0.549), CIFA (τ = 0.525), PAFO (τ = 0.567), THBA (τ = 0.541)
 Primary (2), secondary (2), piscivores (2), planktivore (1)
Negative: ACOL (τ = ), CAJA (τ = ), SUBU (τ = )
 Primary (2) and secondary (1)

11. Discussion What do these results mean for the hypothesis?
No apparent relationship between depth and fish community
Slight relationship between coral cover and fish community
Strong relationship between the composition of fish communities before the bleaching event and after
Suggests possibility for underlying relationship with bleaching
Or perhaps something else?
What did this exercise teach you regarding your overreaching analysis, methods, and objectives?
Community data is complex and NMDS provides a great way to assess many different relationships at once but data exploration is very important to ensure you are getting results actually representative of the real data

12. Discussion: Next Steps
For re-analysis of the data, I would like to do a MRPP test to further investigate the relationship between fish assemblages before and after the bleaching event.
To further this study…
Assess more environmental variables
Structural complexity
Actual depths (rather than zones)
Different sides of island
Other benthic coverage (such as macroalgae, CCA, sand, etc.)
Live vs. dead coral cover
Add data from 2015 surveys
Fish consumer groups