Spring 2022 Assessment
Lake Runnemede is slowly coming back to life after a very long winter. The Lake did not completely freeze over again this winter, which has been true, I think, for four of the past five winters (since I've been looking). The western shore of the lake remains open except for extreme cold snaps (sustained below zero temps), almost certainly because there are 30+ springs along that shore line that pump very calcareous, 45-degree water into the lakes (1.8 million gallons per day). Although vegetation in that area is sparse (due to lack of nutrients in the ground water, the primary "macrophyte" in that area are really charophytes), there is probably enough light coming into the lake to keep nearby floating strands of Coontail (Ceratophyllum demersum) vital through the winter. Ice fisherman reported a few strands of green Coontail fouling their hooks this winter and there were both small fronds and winter buds (balls of green meristems) in the water on March 15, while most of the Lake was still frozen over. At any rate, the first producers that appear in the Lake in noticeable amounts are the filamentous green algae (FGA) that was also present on March 15 and which have formed noticeable blooms along the bottom of the Lake since that time. Over the past week, we've noticed that the FGA has become aerated and is forming floating mats here and there. The spring air (and presumably water) temperature rise had been very gradual through April and early May, but has spiked up into the 80's over the past few days. Macrophytes are starting to appear now as well. In addition to the annual rising of the water lilies (Nymphaea odorata ssp., tuberosa), small rooted pondweeds (Potamogeton ssp.), water starworts (Zosterella dubia) and eelgrass (Vallisneria americana) are also popping up out of the substrate. The rooted macrophytes, particularly the Pondweeds (four species/hybrids of pusilloid or narrow-leaved pondweeds) are extremely challenged in this Lake by a number of environmental (mainly anthropogenic) factors. By late July, the rooted macrophytes will become weighted down by marl (calcium carbonate deposits) and will be outcompeted for by light from the ever-increasing Coontail populations and will therefore have a truncated growing season. Aquatics seem adaptable enough to pull this off - in general the two primary species of Pondweeds (P. foliosus and P. hillii) typically flower and fruit by mid-June, which is 2-3 weeks earlier than in other lakes and ponds in this area. While several rooted macrophytes form dense enough stands to be able to fend off the Coontail incursion (Stuckenia pectinata, V. americana, Z. dubia and P. foliosus) - presumably by producing rhizomes, the primary means of propagation for most of them appear to be either by seed (V. americana) or winter bud (Potamogeton spp.). The hybrid Potamogetons occasionally produce flowers and fruit, but are sterile and spread only by winter bud. Surprisingly, this plant has successfully remained in this lake for at least 135 years and perhaps for millenia.
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