Cyanobacteria Around Bear Island

[ApS]

While rebuilding our piling dock yesterday from formerly-unseen ice damage, I had ample time to check for gloeotrichia. On one occasion, a large and extremely dense concentration drifted by, illuminated by bright sun. (Which brought out their yellow coloration). This colony's movement was driven by our usual eastward "current", the weak breeze, and constant--but moderate in intensity--boat wakes. (These wakes generally favor eastward motion of "our" gloeotrichia).

About twenty minutes later, when I looked again, none could be seen. (Then with the sun blocked by deep shade from shoreline trees).

Originally Posted by Lake Winnipesaukee Assoc

Hi APS,
Great information! The cyanobacteria Gloeotrichia tend to not form blooms, but they do congregate in coves and on shorelines through wind/wave action. Other cyanobacteria types found on Winni, such as Dolichispermum, can form those surface scums that you are referring to. Nutrients most definitely have a part to play in "feeding" these blooms! LWA was recently featured in a Laconia Daily Sun article where we state "Too much phosphorus entering our lake promotes the growth of algae and aquatic vegetation, just like it helps the growth of grass and gardens."

For the record, I haven't referred to natural scum of any kind.

Winter Harbor has its deepest spot just east of Johnson's Cove: Benthic algae is measured there. A small brook feeds into Johnson's Cove, which is fed by 100 acres of open grasslands growing on poor soil, which is mostly clay. Those 100 acres are irrigated daily by lake water sourced from (our now) Phosphorus-rich lakewater.