1. Exploration of patterns in Deep sea coral and sponge communities in the Mariana Archipelago
Multivarite Analysis Goals
Use NMDS to explore community structure at different dive stations in the Mariana geological region
Characterize the environmental parameters of dive sites to determine which variables contribute most to the pattern of species assemblage at each site
Hypotheses
Null: There is no difference in species assemblage between dive sites
Alternate: Species composition between dive sites is different and organized by depth, temperature, and oxygen

2. Data Description 36 sample stations (rows) 107 species (columns)
Family/Genus/species level identifications
Measured in animals per meter traveled
12 Variables
Megahabitat (type of feature)
Habitat (location on feature)
Latitude (decimal degrees)
Longitude (decimal degrees)
Depth max/min (meters)
Temperature max/min (°C)
Oxygen max/min ( µl O2 / l seawater)
Salinity max/min ( PSU)

3. Dataset Processing 63 Species columns Discarded
Criteria: taxa present in fewer than 5 sample rows
3 Sample rows Discarded
Criteria: stations containing fewer than 2 taxa
Transformations
Multiplied species by 1000 (animals per km)
Log-transformed (species data + 1)
Relativizations
Species given equal weight by relativization by column totals
Environmental variables given equal weight by relativization by column totals
Final Sample size for analysis:
33 Stations
44 Species
12 Variables

4. Dataset Exploration

5. Dataset analysis

6. Results interpretation
Criteria for axis selection
Criterion 1: Decline in Stress with added axis at least 5
Criterion 2: P value < 0.05
Final Stress:
Clarke’s rule = thumbs up!

7. Results interpretation
Coefficient of Determination (%Variance Explained)
Orthogonality

8. Results interpretation

9. Results Interpretation
Shallower
Warmer
Less Salty
East
Less O2
L3-05
L3-05
More O2
Deeper
Colder
Saltier
West
Final Stress:

10. Results Interpretation
Shallower
Warmer
Less Salty
East
Less O2
More O2
Deeper
Colder
Saltier
Deeper
Colder
Saltier
Shallower
Warmer
Less Salty
West
Final Stress:

11. Discussion – the Method
Species organized in a 3-dimensional ordination
Alternate hypothesis was supported
Depth/Temp/Salinity axis
Oxygen axis
Longitude
Some types of megahabitats appear to be closer in ordinal space while others are spread out
Not all feature types were well represented in analysis
Only one station represented fore-arc habitat
Only two stations represented in arc and trench
Best Learning outcomes:
understand the limitations of my data
PC-ORD software limitations for analysis

12. Discussion – next steps
For Reanalysis:
Cluster analysis of Species
MRPP between habitats
For more detailed gradient analysis
Cut dive sites into equal length segments for finer gradient resolution
Species Indicator Analysis
Investigate substrate types and habitat features