While it is frequently necessary, many researchers in biology and other natural sciences find dissection of specimens to be undesirable. This is primarily due to the fact that dissection involves the death of the animal being studied, which raises ethical concerns, particularly when the species in question is facing a decline in population.
As a result of these ethical considerations, scientists have developed various non-invasive methods, and one such method is video transects. This technique, commonly used in marine biology, involves divers capturing video footage along a predetermined line of fixed length and depth. It allows for the collection of images that can be analysed (with computer assistance), provides permanent data for future reassessment, and enables researchers to survey larger areas in a shorter time frame.
A recent study published in Marine Biology by Pieter Johnson, a distinguished professor at the University of Colorado Boulder in the Department of Ecology and Evolutionary Biology, along with lead author Cheyenna de Wit from the University of Amsterdam, highlights the advantages of utilising video recordings instead of dissection. In their research on black spot syndrome affecting ocean surgeonfish, the authors employed video transects to assess the severity of the disease across thousands of fish and to identify the environmental factors influencing its spread.
Black spot syndrome encompasses a range of symptoms, with the most notable being the dermal lesions or spots that give the condition its name, as explained by Johnson. He notes that while these lesions are typically black in many species, they can appear white in others. These spots develop on the skin, scales, and fins of the fish. The lesions occur when the free-swimming larval stage of trematodes, commonly referred to as flukes, penetrate the fish’s skin and form cysts within. The characteristic coloration arises as the fish encase the cysts with melanin in response to the invasion, akin to how pearls form in oysters.
There is still limited knowledge regarding the trematode genus responsible for black spot syndrome, Scaphanocephalus. “Before we identified it in 2017,” Johnson states, “it was largely unrecognised.”
