Island-Ocean Connection Challenge Monitoring Data

We developed a suite of standardized approaches to quantify the impact of island restorations on terrestrial and near-shore communities across geographies. Please note not all methods were used in every project. Please review the individual project's metadata for more detailed descriptions of the methods used. A summary of the methodologies follows:

Benthic surveys - Large-area imaging. We use photographic survey techniques to describe the benthic composition from each site. Further, we employ novel approaches of underwater large-area imaging technology to document the spatial structure and competitive dynamics of benthic taxa. This approach can generate multiple digital products, including images collected in the field, composite 3D models, 2D orthorectified images of the 3D models, and annotations of the 2D orthorectified images. These maps, or large-area images, are of sufficient scale to capture thousands of coral colonies, including details of taxonomy, size, and position of all individual colonies. By re-visiting exact locations and replicating the large-area images, we have the unprecedented opportunity to track the dynamics of individual corals and patches of algae. With advanced image analysis we can track how a reef community changes, addressing questions of coral growth, death, and competition.

Benthic surveys - Photoquadrats. Digital photographs are collected to provide raw data on the species composition, relative abundance of sessile benthic taxa, and physiological health of corals, algae, and other benthic taxa. Images are collected with a digital underwater camera using a frame to produce a consistent image area of 0.6m x 0.9m (0.54 m^2).

Benthic surveys - In-situ surveys. We use underwater visual census approaches to enumerate the density, species composition, and relative abundance of sessile benthic taxa.

Fish surveys. We use underwater visual census approaches to enumerate the density, size structure, and species composition of the fish assemblage at each site. The surveys enable us to quantify critical elements of the size structure, trophic structure, and species diversity.

Macroinvertebrate surveys. We use underwater visual census approaches to enumerate the density, size structure, and species composition of the macroinvertebrate assemblage at each site.

Vegetation surveys - High resolution, large-area imagery. We use aerial photographic survey techniques to describe the vegetation composition for each site. Further, we employ structure-from-motion photogrammetry approaches to document vegetation spatial structure. This approach can generate multiple digital products, including images collected in the field, composite 2D orthomosaics, composite 2D and 3D digital surface models, composite 2D and 3D digital terrain models, and composite 2D and 3D canopy height models. These maps, or large-area images, are of sufficient scale to document changes in vegetation percent cover and canopy height, which can be used as ground-truthed data to complement satellite earth observation data and other products to infer biomass and vegetation condition. Images are collected using a drone or other aircraft over the entire island when feasible, otherwise over subsections of the island focusing on terrestrial survey sites. Flights target a ground sampling distance of <10cm and side and forward and overlap of >60%.

Vegetation surveys—plots. We use vegetation plots to document seedling recruitment, percent cover, biomass, and vegetation condition at sites across the island. In addition, this dataset provides ground-truthed data to complement satellite earth observation data.

Vegetation surveys – photomonitoring. We create a visual catalogue of the island at permanent survey points by taking four photos in the four cardinal directions.

Connector species surveys – seabird point counts. We use 5-minute-long surveys of all seabirds on and over land or over water that coincide with marine survey sites to evaluate the diversity and relative abundance of species at each site. Point counts are conducted from a boat at survey locations 50-150m from shore or, in some cases, conducted from the coastline, due to ocean conditions or preferred visibility. We record location of birds (“on or over” the island or over water), behavior (sitting/standing on island or flying) and number of nests observed.

Connector species surveys – acoustic surveys. To document and measure ambient acoustic activity of the nocturnal and diurnal seabird community and quantify diversity and relative abundance, we deploy acoustic recording units at coastal terrestrial sites.

Connector species surveys – land crab transects. We use night-time land crab transects to enumerate the diversity and relative abundance of islands’ land crab community.

Connector species surveys – land crab camera traps. Images are collected using weatherproof “camera traps” set to an hourly, night-time timelapse setting. Images are reviewed to determine abundance and diversity of land crabs within photos.

Connector species surveys – marine iguana large-area imagery. To calculate a population estimate for a subset of marine iguana leks in the Galápagos islands, we utilized a drone equipped with a camera flown from the coastline to approximately 20m inland. An orthomosaic of each lek is constructed, and a count of iguanas observed is completed.

Nutrient availability sampling. Terrestrial vegetation, soil, and near-shore marine macroalgae samples are collected and processed for stable isotope analysis. The results from the stable isotope analysis tell us about the source of nutrients and their availability in the environment.

Environmental context - Remotely sensed data. A suite of remotely sensed meteorological, oceanographic, and topographic data (annual precipitation, elevation, slope, aspect, annual land surface temperature, vegetation type, soil hydrology, chlorophyll-a, wave energy, and sea surface temperature) are collected for each island to provide environmental context.

Environmental context - In-situ data. In-situ water temperature loggers are deployed at four sites (at 10m depth) around each island to provide higher resolution spatiotemporal oceanographic context data.

Environmental DNA - marine data. In unique or sensitive marine environments, like marine lakes, novel approaches have been employed. Aquatic eDNA sampling methods can be used to determine presence/absence of vertebrate species, such as fish. For aquatic sampling, water is pushed through a filter until it clogs, a preservative is then applied to the filter, and the filter is mailed to the lab for sequencing.

Environmental DNA - terrestrial data. Methods were piloted in the terrestrial environment at case study sites Ulong, Late, and Floreana. Our terrestrial eDNA results have the potential to indicate presence/absence of species. Samples were collected from standing fresh water (e.g., lagoon, pond), ephemeral streams following rain events, standing marine water in high tide pools, and soil or sand soaked in bottled drinking or distilled water. Collected or soaked water is pushed through a filter until it clogs, a preservative is then applied to the filter, and the filter is mailed to the lab for sequencing.