June Programs Update
Published: June 16, 2023
As usual with a complex watershed system, we have a mix of good and some not-so-good news on the Severn River this spring.
First, the good news: 2023 is shaping up to be a goodyear for our oysters. At the time of this writing, conditions are ripe to support an oyster spawn (natural reproduction) right here in our home waters! The key factors are water temperature and salinity. Oysters can spawn when temperatures exceed 20 degrees C and salinity exceeds 10 parts per thousand (ppt). One June 14, temps were 22.5 degrees C and salinity was at 10.6 ppt. Additionally, the 30 million oyster spat-on-shell we just planted and the 32 million planted in 2022 are oysters that can reproduce when salinity is as low as 5 ppt. Our river routinely exceeds the 5 ppt level.
Now the bad news: increased areas with hypoxic conditions (areas with very little oxygen) are being found outside of our oyster restoration reef areas between the Rt. 50 and USNA Bridges. Our teams have recorded these temporary zones at our monitoring stations in Round Bay, the Narrows, Indian Landing, and inside some creeks, particularly, Weems, Luce, and Whitehall Creeks.
These hypoxic zones are a result of the excessive levels of algae activity we spotted in May and early June during our weekly monitoring. Fortunately, we haven’t seen the full-blown effects of a Mahogany Tide this year, but the high levels of algae activity (fed by nitrogen pollution from lawn fertilizers, auto/truck emissions, pet and animal wastes) are what create the hypoxic zones because when algae die, their decomposition is what depletes the oxygen from the water.
Hopeful signs for underwater grasses – the fabled submerged aquatic vegetation (SAV) are also noted with healthy patches of Horned Pondweed floating on the river. This particular SAV thrives from March through early June and spread their seeds this time of year by releasing themselves from the river bottom and floating with the tides. These seeds, which look like little horns, hence the name, typically germinate in the fall, so let these patches of pondweed float on by.
They’re being replaced by summertime SAV which are usually mix of redhead, widgeon and sago pondweed. SAV are important because they:
· add oxygen to the water (this helps oysters thrive!)
· provide food and shelter for birds, fish, crabs, and muskrat
· protect shorelines from erosion
· clean and filter the water
· sequester carbon
Some boaters, swimmers and anglers, may frown at SAV at times, but please put up with the annoyance because SAV are absolutely vital to the health of the Severn River.
Lastly, we have held two Floating Classroom sessions so far, with 7 more to go with new partners Boys and Girls Club of Annapolis and the City of Annapolis Police Department summer program. This SRA program teaches students about water quality, oyster restoration, conservation efforts, climate change, and the impact human choices have on the environment around us.