Abstract
Habitat loss is a serious issue threatening biodiversity across the planet, including coastal habitats that support important fish populations. Many coastal areas have been extensively modified by the construction of infrastructure such as ports, seawalls, docks, and armored shorelines. In addition, habitat restoration and enhancement projects often include constructed breakwaters or reefs. Such infrastructure may have incidental or intended habitat values for fish, yet their physical complexity makes quantitatively sampling these habitats with traditional gears challenging. We used a fleet of unbaited underwater video cameras to quantify fish communities across a variety of constructed and natural habitats in Perdido and Pensacola Bays in the central northern Gulf of Mexico. Between 2019 and 2021, we collected almost 350 replicate 10 min point census videos from rock jetty, seawall, commercial, public, and private docks, artificial reef, restored oyster reef, seagrass, and shallow sandy habitats. We extracted standard metrics of Frequency of Occurrence and MaxN, as well as more recently developed MeanCount for each taxon observed. Using a simple method to measure the visibility range at each sampling site, we calculated the area of the field of view to convert MeanCount to density estimates. Our data revealed abundant fish assemblages on constructed habitats, dominated by important fisheries species, including grey snapper Lutjanus griseus and sheepshead Archosargus probatocephalus. Our analyses suggest that density estimates may be obtained for larger fisheries species under suitable conditions. Although video is limited in more turbid estuarine areas, where conditions allow, it offers a tool to quantify fish communities in structurally complex habitats inaccessible to other quantitative gears.
Highlights
Habitat loss is a serious issue threatening biodiversity across the planet [1,2], and coastal marine habitats are no exception
Our aim was to compare patterns among metrics, and because the different bays were sampled in different years and seasons, interpretations should be limited to comparisons of metrics, rather than representing robust analyses of spatial patterns in fish community structure
Eight of the videos from which we extracted Frequency of Occurrence (FoO) and MaxN were excluded from the density dataset due to structures obstructing part of the field of view (FoV) or cameras falling over, but still provided a clear FoV to derive FoO and MaxN
Summary
Habitat loss is a serious issue threatening biodiversity across the planet [1,2], and coastal marine habitats are no exception. It is challenging to quantitatively sample fish communities in structurally complex habitats [15] Active sampling gears such as trawls or seine nets are ineffective in complex habitats. Passive gears such as traps or gill nets can be used, but these gears can be quite species- and size-selective, making them less suitable for quantitative assessments of fish community composition [15]. Underwater video is becoming increasingly used in shallow coastal waters [16,17,18] It has several benefits over other gears and methodologies. Video sampling is non-extractive, making it suitable for use on protected or regulated species or in sensitive habitats, and it can be deployed without requiring personnel to enter the water. Underwater video has been used successfully across a wide range of estuarine conditions, e.g., [21]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
