Fig 1.
(a) Location of South-East Tasmania, (b) the study region in the Derwent Estuary, and (c) the nine Derwent estuary study sites highlighted in red. Abbreviations for each site: Battery Point (BP), Bellerive Beach (BR), Howrah Beach (HB), Half Moon Bay (HMB), Mary-Ann Bay (MAB), Opossum Bay (OP), Ralphs Bay (RB), Tranmere (TR) and Sandy Bay (SB).
Fig 2.
Example of points of interests (POI) captured during each dive.
Screen capture of a standard GUVC dive using HOLUX ezTour for Logger. The purple track represented each transect with the camera icon represented geotagged photographs. POI including diver’s signal (b,d) were captured to identified the searched area. In addition, sighting of fish was also recorded using the camera system to identify the location of each sighting (c).
Fig 3.
Example of each defined microhabitat features.
Letter denote the corresponding microhabitat class in Table 1.
Table 1.
Operational definition of microhabitat features found across all surveyed B. hirsutus sites.
Fig 4.
B. hirsutus density (mean ± CI fishes Ha-1) estimated at each site. Letters above each bar represented significant grouping of data based on post-hoc pairwise analysis (Tukey HSD test) of transformed data. Standard error for Bellerive (BR) was not presented as only a single fish was found. Site abbreviations as in Fig 1.
Fig 5.
Frequency of microhabitat features by site.
Total count of each microhabitat feature classes at each site. Microhabitat feature classes and site abbreviations as in Table 1 and Fig 1.
Fig 6.
Habitat preference of spotted handfish.
(a) Frequency of microhabitat features where B. hirsutus were absent (light grey) and present (dark grey). (b) Habitat preference score (observed proportion—expected proportion) of B. hirsutus for each microhabitat feature class. Microhabitat class abbreviations as in Table 1.
Fig 7.
Spotted handfish, habitat relationship observations.
Photos of B. hirsutus observed near each defined microhabitat. The letter denoted the abbreviation for each feature: SF-sand flat; SS-sand flat with structures; SD-sand flat with depression; SDF-sand flat with filled depression; SR-sand ripple; SRF-filled sand ripple; R-rocky reef; V-vegetation mat; BG-Biogenic mat; GF-gravel flat; GS-gravel flat with structures; GDF-gravel flat with depression.
Fig 8.
Spotted handfish survey power analysis.
Average (±SD) power of detecting B. hirsutus density changes over time with different sample size (number of GUVC transects) simulated from the 2015 dataset. Analysis were conducted at three different level of changes (light grey– 75%; dark grey– 50%; black– 25%).