A novel approach for in situ benthic habitat characterization

Habitat heterogeneity is a key driver of temporal and spatial variability of subtidal marine benthic biodiversity. However, this makes it a challenging environment in which to measure and quantify the factors driving biodiversity in a consistent manner. Current methodologies are either expensive, logistically challenging, require extensive technical knowledge, or are limited to shallow water environments. To overcome some of these limitations, a novel “SeaPen” device was designed as a cost‐effective, safe, easily deployable instrument that can provide repeatable and comparable survey results over the small spatial scales required to describe heterogeneous environments. The device, which comprises a tripod frame holding a steel weighted bar in the center, allows gravity to force a graduated metal spindle into the substratum when it is dropped. A video camera fixed to a tripod leg allows the recording of the nature of the seabed and the depth of penetration of the spindle, from which seabed properties can be described. The device does not need to be recovered to the surface between measurements, which allows it to be repeatedly dropped for multiple replicates in a single deployment. The combination of a penetrating spindle and a camera allows for rapid repeat measures and, most importantly, can be used to measure heterogeneity on finer scales (within a site; m) than other more traditional techniques. The SeaPen was used in a shallow water (<50 m) coastal habitat on the West Antarctic Peninsula. The survey area comprised heterogeneous substrata composed of sediments interspersed between boulders, cobbles, and pebbles, which allowed for proof of concept that the SeaPen could discriminate a wide range of seabed habitat types.