The Smithsonian Institution
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MarineGEO Visual Census Protocol

online resource
posted on 2021-07-09, 18:46 authored by Tennenbaum Marine Observatories Network, MarineGEO
Visual census provides a rapid, non-destructive way to quantify abundance of macroscopic organisms across a range of ecosystems where visibility is sufficient (coral reefs, subtidal rocky reefs, seagrass meadows). This protocol describes the Diver Visual Survey method for estimating densities of fishes, other swimming animals (e.g., turtles, cetaceans), and large macroinvertebrates > 2.5 cm at maturity (e.g., gastropods, echinoderms, crustaceans).

These methods are identical to, and adopted from, those employed by the Reef Life Survey (RLS) network, and diver visual survey data collected as part of MarineGEO activities will be integrated into both MarineGEO and RLS global databases. We provide an abbreviated summary of their detailed protocol, but those working in high diversity systems, with schooling fishes, in kelp forests, or facing other challenges may wish to consult the RLS Manual directly for further details:

This assay records species composition, density, diversity, and body sizes of fishes and other swimming animals in a 50 x 10 x 5 m transect (Method 1), measured as:
• Number and identity of all mobile organisms
• Total length (snout to tip of tail) of swimming animals

It also records species composition and density of mobile invertebrates and cryptic fishes in a 50 x 2 x 1 m block along the same transect (Method 2), measured as:
• Number and identity of macroinvertebrates and cryptic fishes
• Total length (snout to tip of tail) of cryptic fishes