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Improved access to multibeam sonar and underwater video technology is enabling scientists to use spatially-explicit, predictive modelling to improve our understanding of marine ecosystems. With the growing number of modelling approaches available, knowledge of the relative performance of different models in the marine environment is required. Habitat suitability of 5 demersal fish taxa in Discovery Bay, south-east Australia, were modelled using 10 presence-only algorithms: BIOCLIM, DOMAIN, ENFA (distance geometric mean [GM], distance harmonic mean [HM], median [M], area-adjusted median [Ma], median + extremum [Me], area-adjusted median + extremum [Mae] and minimum distance [Min]), and MAXENT. Model performance was assessed using kappa and area under curve (AUC) of the receiver operator characteristic. The influence of spatial range (area of occupancy) and environmental niches (marginality and tolerance) on modelling performance were also tested. MAXENT generally performed best, followed by ENFA-GM and -HM, DOMAIN, BIO-CLIM, ENFA-M, -Min, -Ma, -Mae and -Me algorithms. Fish with clearly definable niches (i.e. high marginality) were most accurately modelled. Generally, Euclidean distance to nearest reef, HSI-b (backscatter), rugosity and maximum curvature were the most important variables in determining suitable habitat for the 5 demersal fish taxa investigated. This comparative study encourages ongoing use of presence-only approaches, particularly MAXENT, in modelling suitable habitat for demersal marine fishes. KEY WORDS: Species distribution modelling · Multibeam sonar · Towed-video · MAXENT · ENFA · BIOCLIM · DOMAIN Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 420: [157][158][159][160][161][162][163][164][165][166][167][168][169][170][171][172][173][174] 2010 Parallel to the development and application of species distribution modelling in the marine environment, is the increasing access to multibeam sonar (MBES) technology and underwater video systems. These technological developments, coupled with advances in geographic information systems and computational power, make it possible to survey large regions of seafloor with unprecedented accuracy and resolution (Nasby-Lucas et al. 2002, Iampietro et al. 2005, Wilson et al. 2007. MBES datasets are ideal for the application of a variety of terrainanalysis techniques, which form predictor variable datasets for input into models (see Wilson et al. 2007).While traditionally used for assessing sessile species, 'passive' underwater video systems such as drop video, towed/drift video and remotely operated vehicles (ROV) are increasingly being used as cost-effective, non-destructive methods for assessing marine fish species distributions (Morrison & Carbines 2006, Anderson & Yoklavich 2007. These video-based survey methods have significant advantages over traditional methods (e.g. SCUBA divers) in collecting fish occurrence data. They are capable of being deployed at depths and times that are dangerous for ...

Monitoring of intertidal reefs is traditionally undertaken by on-ground survey methods which have assisted in understanding these complex habitats; however, often only a small spatial footprint of the reef is observed. Recent developments in unmanned aerial vehicles (UAVs) provide new opportunities for monitoring broad scale coastal ecosystems through the ability to capture centimetre resolution imagery and topographic data not possible with conventional approaches. This study compares UAV remote sensing of intertidal reefs to traditional on-ground monitoring surveys, and investigates the role of UAV derived geomorphological variables in explaining observed intertidal algal and invertebrate assemblages. A multirotor UAV was used to capture <1 cm resolution data from intertidal reefs, with on-ground quadrat surveys of intertidal biotic data for comparison. UAV surveys provided reliable estimates of dominant canopy-forming algae, however, understorey species were obscured and often underestimated. UAV derived geomorphic variables showed elevation and distance to seaward reef edge explained 19.7% and 15.9% of the variation in algal and invertebrate assemblage structure respectively. The findings of this study demonstrate benefits of low-cost UAVs for intertidal monitoring through rapid data collection, full coverage census, identification of dominant canopy habitat and generation of geomorphic derivatives for explaining biological variation.

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