Fig 1.
Key administrative boundaries in Saipan Lagoon.
These boundaries include existing jet ski exclusion zones and potential jet ski operation zones, potential new technology (seabreachers, hydroflight devices) use zones, and transit corridors. These boundaries are overlaid on locations where staghorn Acropora (pictured above) has been documented, and where it is more likely to be found elsewhere in the Lagoon. The existing jet ski exclusion zones extend up to the reef crest, and appear offset because of the coarse scale at which they were digitized.
Fig 2.
Diagram depicting steps in modeling process to predict staghorn Acropora distributions and quantify the uncertainty associated with these predictions.
Table 1.
Model parameters and values tested during the BRT tuning process.
The combination of parameter values (i.e., lc = 0.005, tc = 3 and bf = 0.75) with the highest percent deviance explained were identified using 10-fold cross validation, and then used to create the spatial prediction for staghorn Acropora in Saipan Lagoon.
Table 2.
Performance of methods used to optimize the probability of occurrence threshold.
Performance metrics included accuracy, sensitivity, specificity and Kappa. Note that the SES and MSS approaches resulted in the same threshold value (0.04).
Fig 3.
Optimizing probability of occurrence thresholds.
Four methods were evaluated for choosing a threshold using a ROC curve, including SES, MSS, Kappa and PPOP. Plot created using ‘PresenceAbsence’ package in R software.
Table 3.
Combinations of probability and precision thresholds.
Nine staghorn Acropora presence/absence maps were created using these nine combinations of probability and precision.
Fig 4.
Locations where staghorn Acropora have a higher probability (0.29) of occurring.
These high probability locations are divided based on high, moderate and low precisions. The bar graph depicts the amount of area (km2) inside and outside the existing jet ski exclusion zones predicted to have staghorn Acropora. The number above each bar denote the predicted area in km2. The colors and groups in the bar graph match the colors and groups in the map.
Fig 5.
Locations where staghorn Acropora have a moderate probability (0.17) of occurring.
These moderate probability locations are divided based on high, moderate and low precisions. The bar graph depicts the amount of area (km2) inside and outside the existing jet ski exclusion zone predicted to have staghorn Acropora. The number above each bar denote the predicted area in km2. The colors and groups in the bar graph match the colors and groups in the map.
Fig 6.
Locations where staghorn Acropora have a low probability (0.04) of occurring.
These low probability locations are divided based on high, moderate and low precisions. The bar graph depicts the amount of area (km2) inside and outside the existing jet ski exclusion zone predicted to have staghorn Acropora. The number above each bar denote the predicted area in km2. The colors and groups in the bar graph match the colors and groups in the map.
Table 4.
Predicted staghorn acropora inside proposed jet ski zones.
Amount (m2) of predicted staghorn Acropora inside the proposed jet ski operation zones. Proposed jet ski operation zones are sequentially numbered from north (#1) to south (#6).
Fig 7.
Jet ski activity offshore of four hotels in Saipan.
The hotels include (clockwise) the Hyatt Regency, Fiesta Resort (satellite image taken 2/5/2016), Grandvrio Resort (11/7/2013), and Kanoa Resort (3/5/2013). The yellow arrows point out people using jet skis. The black boxes denote the existing jet ski exclusion areas, and the red boxes show the potential jet ski operation areas. The light to dark blue pixels denote locations where staghorn Acropora is predicted to be present (based on low probability and low, medium and high precisions, respectively).