M
Mike
Well-known member
- Joined
- Nov 10, 2006
- Messages
- 5,562
Received from DRBC's Eric Silldorf:
Today we got confirmation from the Academy of Natural Science that Didymo is present in the Delaware River all the way down to Trenton. There is a big difference in growth form, however, at all stations that I’ve examined below the Lehigh River. Above the Lehigh confluence (including one site just 0.5 miles above the confluence), you can see the classic cotton-like growth on large areas of the riverbed in suitable habitats (moderate to higher flows, hard substrates, sufficient depth to have remained wet over the past few weeks).
Below the Lehigh, there is no apparent coverage of Didymo when examining in the field.... the river looks to have a normal, thin coverage of diatoms and other algae as a biofilm on the rocks. But at three sites now, spanning Scudders Falls access near Trenton (river mile 139) to the Wy-Hit-Tuk access just below the Lehigh (river mile 181), every rock that I’ve returned to the lab has sizable growths of Didymo that can be seen under either a dissecting or a compound microscope. The big difference appears to the be stalk formation being very short and limited in extent at all sites below the Lehigh, and thus the lack of a macroscopic “rock snot” type look to any of these areas. But the Didymo is still growing and is plenty abundant below the Lehigh, so the risk of spread would appear to be very high, I believe.
Today we got confirmation from the Academy of Natural Science that Didymo is present in the Delaware River all the way down to Trenton. There is a big difference in growth form, however, at all stations that I’ve examined below the Lehigh River. Above the Lehigh confluence (including one site just 0.5 miles above the confluence), you can see the classic cotton-like growth on large areas of the riverbed in suitable habitats (moderate to higher flows, hard substrates, sufficient depth to have remained wet over the past few weeks).
Below the Lehigh, there is no apparent coverage of Didymo when examining in the field.... the river looks to have a normal, thin coverage of diatoms and other algae as a biofilm on the rocks. But at three sites now, spanning Scudders Falls access near Trenton (river mile 139) to the Wy-Hit-Tuk access just below the Lehigh (river mile 181), every rock that I’ve returned to the lab has sizable growths of Didymo that can be seen under either a dissecting or a compound microscope. The big difference appears to the be stalk formation being very short and limited in extent at all sites below the Lehigh, and thus the lack of a macroscopic “rock snot” type look to any of these areas. But the Didymo is still growing and is plenty abundant below the Lehigh, so the risk of spread would appear to be very high, I believe.
