Development of benthic monitoring methods using photoquadrats and scuba on heterogeneous hard‐substrata: a boulder‐slope community case study

Abstract

ABSTRACT1. Photoquadrats enable efficient and cost-effective quantitative estimation of epibenthic communities. Despite their utility, however, there has been limited use of photoquadrats for such purposes in temperate north-west Europe, where there is also a growing need for standardized approaches to marine monitoring.2. A rapid photoquadrat-based methodology was trialled by scuba divers on a heterogeneous boulder-slope habitat in a Special Area of Conservation (SAC) in Northern Irish waters. To investigate the monitoring potential of the method, the benthic community was randomly sampled in the summers of 2009 and 2010. The community was represented at species level (community composition) and by functional group (community structure), and the data-extraction resolution was varied using different numbers of point intercepts per image (25, 50, and 100) to assess the balance of precision and efficiency with regard to detection of community change.3. The method was efficient in situ and yielded sufficient sample images for estimation of local benthic community diversity (number of species). The community varied significantly, with six distinct sub-communities identified within the survey area. High spatial variability obscured detection of temporal changes in the overall community composition and structure. However, spatial variability was substantially reduced by testing only the dominant sub-community, in which significant changes were detected between 2009 and 2010.4. The ability of the photoquadrat to detect individual taxa was related to data resolution: the more point-intercepts sampled, the more taxa were discovered, but the data-extraction effort was greater. After considering the ability of the photoquadrat method to quantify number of species and to detect change in community structure, as well as its precision and efficiency, the inspection of 50 point intercepts per sample image was found to be optimal. These findings demonstrate the benefits of photoquadrat-based methods and highlight their potential as a standard approach to marine monitoring.

Cost-benefit of three different methods for studying Mediterranean rocky benthic assemblages

“…Diving time is short but the subsequent frame treatment is long. Cover data is finally estimated using sub-quadrats (Bussotti et al 2006, Deter et al 2012, contact points (Foster et al 1991, Meese and Tomich 1992, Van Rein et al 2011 or species patches , Piazzi et al 2014. These methods have increased in popularity and specific image processing software for them has been released (e.g.…”

Study of the influence of physical, chemical and biological conditions that influence the deterioration and protection of Underwater Cultural Heritage

“…The photoquadrat apparatus was constructed from PVC and attached to the underwater housing camera following other studies (Preskitt et al, 2004;Van Rein et al, 2011). Abundance estimations were made calculating the percentage cover by 100 fixed point-interception (Van Rein et al, 2011;Masi et al, 2009;Van Rein et al, 2012) using image analysis software NIS-Elements Advanced Research V.4.0 (Nikon NIS-Elements Advanced Research, 2014). In the two studied substrates, specimens were identified to the lowest taxonomic level of resolution possible, in most cases to species level.…”

Field manuals for marine sampling to monitor Australian waters

“…Van Rein et al (2011) and Perkins et al (2016) suggest that, while a higher number of points per image can increase the detection rate of more organisms within an image, increasing the number of scored images using fewer points is likely have a similar (or greater) effect. Ideally, increasing both the number of images scored and the number of points scored within an image would result in greater power (Roelfsema et al 2006), but preference is usually for increasing the number of images (Perkins et al 2016).…”