Pointers at Glance
- According to a new study of the Los Angeles and Long Beach area published in the journal PeerJ, measuring marine biodiversity with “environmental DNA,” an application of gene sequencing to environmental biology, must allow rapid assessment of marine life changes.
- That makes environmental DNA (eDNA) an important tool for managing the response to climate change. But eDNA functions well only if key implementation steps are followed.
Several academic institutions, environmental consultants, and government agencies worked on highlighting the challenges involved in using eDNA.
Zack Gold, the lead author of the study, said that eDNA uses genetic sequencing of samples from the environment to inventory biodiversity. Some genes differ enough between species to be used as identification markers. Every organism sheds DNA by dropping skin cells or other materials so one can take a cup of seawater, sequence the DNA in it, and use that to inventory organisms in the area.
The Port of Long Beach and the neighboring Port of Los Angeles form one of the largest port complexes in the world and are a site of intense environmental interest. That made it an interesting site to test the ability of eDNA to act as an effective tool for biodiversity assessment.
Researchers collected multiple eDNA samples at each site of the seven sites in the port complex, each about one liter of seawater, just before the trawl net was towed through the same area.
That permitted a comparison between eDNA and traditional biodiversity assessment techniques: eDNA detected approximately all 17 species of fish found in the trawls but also detected an additional 55 native species. Detecting those additional species through conventional sampling needs much more sampling trips and a very high expense.
The eDNA samples from various locations in the ports resulted in different species inventories at a statistically significant level. The authors gathered a set of recommendations for managers considering eDNA as a tool for biodiversity assessments. The recommendations include carefully selecting the identifying genes and specific advice on cleaning up the sequence data from eDNA samples before searching for sequence matches.
Because of the successful species resolution that resulted from building a full sequence reference library, the main recommendation is to create regional reference databases. The Port of Los Angeles and the Port of Long Beach funded the project.