Community Scientists Set the Bar(code) for Future Fish Surveys in Monmouth County Waters

The swirling gene pool that is Monmouth County's ocean and estuarine waters was home to at least 68 species of fish this fall. That was one of the findings of an analysis of environmental DNA (eDNA) extracted from water samples taken at local beaches, bays and tidal rivers by community scientists partnering with the Monmouth University Urban Coast Institute (UCI).

Beginning in September, Monmouth researchers provided equipment and instruction to the volunteers to collect and return the samples, which were lab analyzed for eDNA - trace genetic materials floating in the water can indicate the presence of marine life. On Nov. 20, the volunteers gathered on campus for a meeting to learn about the study method and what their jars of water contained.

Endowed Professor of Marine Science Jason Adolf explained that the eDNA shed into the water by marine organisms carries signatures, called metabarcodes, that can indicate what species it's from. Since these materials tend to break down in the water in about a day, a detection indicates that it was likely in the area over the last few hours, if not at that moment.

"It's like barcoding at the supermarket, where instead of the person having to find the price tag for each item, you just scan it and the computer knows what it is," Adolf said. "We have a database for all of the barcode sequences of fish, marine mammals, turtles and humans, and when we detect it in the natural sample, we can tell that a fish was there, and to some extent, how many of the fish were there."

The volunteers collected samples at 22 stations from the Manasquan Inlet to the Raritan Bay. The following are some of the results:

• In the estuaries, the most common fish was mummichog, followed by Atlantic silverside and Atlantic or Gulf menhaden, with a caveat. Since river herring's metabarcode is difficult to distinguish from Atlantic menhaden (commonly called bunker), they were paired together. If the possible river herring detections were actually menhaden, it would be the second most-detected fish.
• In the ocean, the most detected fish was tautog, followed by menhaden, black drum or spot, and river herring or menhaden.
• Elasmobranch species (sharks and rays) were counted separately. In the estuaries, the most common detection was for the sand tiger shark, while in the ocean it was the clearnose skate and smooth dogfish.
• The highest number of fish species detected was at an Asbury Park beach with 27, followed by 24 at a beach near the Shark River Inlet in Belmar. The Raritan Bay locations tended to show lower species richness than the estuaries to the south. A site in Manahassett Creek, a branch of the Shrewsbury River in Long Branch, showed the fewest fish species (3).

The data will be used to help develop a baseline understanding of what species eDNA shows to be living in Monmouth area waters that can be compared to future results.

"Each species plays a very important role in the function of their ecosystem, and as biodiversity decreases, ecosystem function decreases," UCI Resilience and Outreach Project Lead Richard Kane said. "It's important that we monitor biodiversity because ecosystem function - the working of the planet - is reliant on there being biodiversity and allowing these functions to continue."

Kane said a second round of sampling will be conducted in the summer. Those interested in participating can email [email protected].