NewSampling TechniquesforSpecies CatalogingUtilizing eDNA

ByAlexandriaRobinson,UHMMOPStudent

The rangeof fields of study in the biological sciences spans from the tallest mountain to the deepest part of thesea and is ever-evolving. New technologies areconstantly making collecting information about our natural world more accessible and quantifiable. Currently one of the biggest issues facing modern biological scientists is the ability to quantify thenumber of species in large ocean areas. Many topics including biodiversity indexing,species migration,and species invasion have been incredibly intensive in terms of the labor,time,and funding they require. As a result,these challenges have limited the scope of potential discoveries in the field of biology.

However,as technology evolves,so too do the sampling techniques.Some of thebest large-scalesampling tools previously utilized were expensive satellites. Satellites do not always offer great resolution and accuracy, and face limitations in their wider application to deep-sea environments. Now,environmental DNA,also called eDNA,is taken from anywhere including air,soil, and even water to sample for possible identification from the residual shedding of DNA that organisms naturally do. In thecase of the USMarine Biodiversity Observation Network (MBON), eDNAis being used in theoceans to catalog species at a lower cost and much more efficiently than having large research crews try to sail between locations hoping to catch proof of a species living there.

USMBON has set up monitoring stations within the national marine sanctuaries for fish monitoring that could better inform scientists about abundance, breeding habits,location,and efficacy of these marine sanctuaries to better inform fisheries practices. These samples can include secretions such as mucus,waste,reproductive gametes,and dead tissue. All samples can have a rangeof viability with the genetic information preserved with the tests,either being performed on 12SrDNAfor vertebrates,16S rDNA for microscopic organisms, 18SrDNAfor planktonic species,or COI for invertebrate species.

Samples are often collected using remotely operated vehicles (ROVs),filtered,and brought to a wet lab to conduct PCR amplification of theDNA that is later sequenced to be uploaded to a shared database. There are some ?dark taxa?that have yet to be described so they cannot be matched in these databases but are still important for future research. Traditional mass sequencing is also more cost effective than smaller scale PCR amplification of DNA.

Water does tend to degrade eDNA segments as well as high wave action in oceanic mixing from air movement and tidal shifts,but not all hopeis lost for this eDNA. Research has shown lower temperatures are much better for preserving the integrity of the eDNA,which is why many samples areplaced on ice in the lab while processing. This could mean that lower oceanic temperatures, especially in coastal upwelling marine sanctuaries keeps the eDNAfrom being completely unusable as soon as it is shed.

One research team was able to match 42 different species of fish to their eDNAthat was shed, with 80%of those identified being common local species. This is promising for indexing species as a whole instead of individually. Currently,the most important aspect of refining the use of eDNA as a viable sampling technique is unifying the methodology of sampling. Continued use of eDNA to lower thenumber of ?dark taxa? along with this conformity of sampling methods will continue to build repeatable and useful long term mass monitoring in our marine sanctuaries whilebeing more labor and cost effective.