Fig 1.
DEACs deployed on four-legged rebar stands in the field.
Plastic cable ties attached to the camera housing and to the legs were used to secure buoyant cameras in housings below the crossed rebar at the top of each stand. Bottom left inset: A detailed front view of a camera in Housing 1 underwater. Reprinted from [39] under a CC BY license with permission.
Fig 2.
Camera arrangement at a patch reef site.
One camera was placed on the edge of the halo facing in toward the reef (“Halo Cam”), while the second (“Control Cam”) was placed twice the halo’s width away in the surrounding seagrass or algal cover, in line with the first camera. Modified from [39] with permission.
Fig 3.
Empty (left) and fish-filled (right) images captured at the same camera site within 24 hours. The empty or “NoFish” photo was assigned only a 0.09 probability of containing a fish by our ResNet-50 model, whereas the model predicted a 0.88 probability of the second photo containing at least one fish, hence its “Fish” designation. Probabilities like these were used to sort images into “Fish” and “NoFish” categories to streamline further analysis. Reprinted from [39] under a CC BY license with permission.
Fig 4.
Comparison of biofouling and algal overgrowth after a month based on location.
Structures were located at the edge of the halo, adjacent to seagrass (left), and in the middle of the surrounding seagrass (right). Similar results seen across all camera sites suggest that reef-based herbivores help to control algal growth both within and at the edges of the halo but do not graze heavily, if at all, on algae and related marine organisms in the surrounding algal or seagrass beds. Reprinted from [39] under a CC BY license with permission.
Table 1.
Accuracy of model predictions.
Fig 5.
Non-metric multidimensional scaling (NMDS) based on presence/absence data.
Points represent 20 individual site observations by divers or 3 pooled images from 18 given sites and are colored purple for halo/reef cameras and dark green for seagrass or algae cameras. ANOSIM of this NMDS output found a significant difference between halo/reef (purple) and seagrass/algae (green) communities (R = 0.68, p<0.001). Dots represent diver observations, while triangles represent camera images. Both diver and camera observations reflect the same clear difference between fish communities on the reef and those in the seagrass. See S5 Fig for a stressplot of this NMDS.
Fig 6.
Proportion of images containing fishes at halo and grass/algae sites inside and outside of the Half Moon Caye MPA.
Halo sites are represented in shades of purple, seagrass/algae sites in shades of green. Each bar is a proportion based on the n for that treatment. Error bars represent ± 1 standard deviation from the binomial distribution, scaled by the respective n for each treatment.
Fig 7.
Time series showing smoothed data from 40 different cameras deployed asynchronously between March 2018 and March 2019.
(A) Fish probabilities for individual images in halo/reef and seagrass/algae habitats by time of day. Probabilities ranged from 0 to 1 for this dataset, but smoothing visually compresses the highest and lowest probability values on the graph. (B) Fish probabilities for images by date, showing variation over the course of one year at Lighthouse Reef Atoll. Trend lines for all groups were generated using the geom_smooth function with method “loess” in ggplot2 [53]. Light gray shading represents 95% confidence intervals.