# Object-Based Mapping of Coral Reef Habitats Using Planet Dove Satellites
## 2 Materials and Methods
### Field Data Collection  
From 30 April to 4 May 2018, a total of six field transects were generated to measure and assess a diverse array of benthic compositions within the three study sites (Catalina Island, Saona Island, and Eastern Dominican Republic, Figure 1). Bathymetric field measurements were collected using a Lowrance Elite7T1 (Tulsa, OK, USA) system with a \(\propto\)Sonic P319 (50/200 kHz) transducer and 10 Hz GPS receiver that collected continuous depth readings at 3 pts/sec along each transect. In parallel, a GPS-referenced SeaViewer Sea-Drop 6000 HD (Tampa, FL, USA) underwater video camera with 30 m vertical cable was used to record benthic habitat types along each transect (Table 1). A total of 152.4 km of bathymetric measurements and 122 benthic video samples were recorded along all transects. From these data, we generated 5300 bathymetric measurement points at a 15 m interval. Benthic habitat types (coral reef crest, coral patch deep, coral back-reef/flat, coral fore-reef, goropian/soft coral, hardbottom with algae, seagrass dense, seagrass sparse, sand shallow, and sand deep with sparse macroalgae) were classified for each video sample (Table 1). A total of 3000 points were applied as the training samples for the object-based classification. The remaining 2300 points were used for model verification. We selected the training and verification points based on depths and habitat types.  
Figure 1: Planet Dove mosaic imagery (shown in RGB true color) covering three study sites within the Arrecifes del Sureste marine sanctuary in southeastern Dominican Republic (DR): Catalina Island (**a**), eastern Dominican Republic (**b**), and Saona Island (**c**). Field data transects are shown as red lines. The general location of the study region is provided in the lower right panel.  
\begin{table}
\begin{tabular}{c c c} \hline
**Benthic Habitat Type** & **Description [16]** & **Field Video Example** \\ \hline Coral Reef Crest & Coral Reef Crest is found in shallow water break zones. The benthic cover consists of coral build up and turf/calacreous algae. Large fleshy macroalgae are largely absent and only small coral colonies were observed. & \\ Coral Patch Deep is typically covered with a veneer of turf algae and a sparse (\(<\)5\%) cover of scleratinian coral, hydrocoral, gorgonians, sponges, and macroalgae. Typically found on the exposed margins seaward beyond the reef crest, above \(\sim\)10 m depth where large waves may scour the seafloor. & \\ \end{tabular} \
\begin{tabular}{c c} Skeletal rubble originating from reef structures and bonded by coralline algae to form a semiconsolidated framework with patchy macroalgae. Typically found on the sheltered margins landward of the reef crest. This habitat may also be found surrounding or atop carbonate frameworks. & \\ Coral Fore- reef & Moderately rugose frameworks with sparse coral cover (typically \(<\)10\%). Colonies are predominantly small (submeter) in size. Typically found on the exposed seaward slope of the reef crest. The coral community is composed primarily of _Siderastrea_, _Montastra_, _Dipolara_, and _Colophyllia spp_. _Crustose_ coralline algae and fleshy algae (_Sargasum_, _Dicytota_) along with gorgonians dominate the remainder of substrate. & \\ Coral Fore- reef & Areas of a framework formed of massive coral species such as _Montastrea_ or _Dendrogyna_. The coral structure may or may not have a living coral veneer. The reef maintains the coral form. Live coral cover is patchy (\(<\)15\% overall). Gorgonians dominate the substrate between corals. & \\ \end{tabular}
\begin{tabular}{c c} Hardbottom with Algae & Reef framework heavily dominated by macroalgae and occasional gorgonians. Coral cover is typically low (\(<\)5\%). \\ \end{tabular}
\end{table}
Table 1: Benthic composition classification scheme.