Rainbow Springs was my first trip on this odyssey. It was a good first choice because it was absolutely gorgeous. The water clarity was amazing and the beds of macrophytes (plants) were lush. Although I did not map the vegetation, a significant portion of the Rainbow run substrate was covered with vegetation (many of the dark areas in the Google Earth image below). Much of the watershed of Rainbow Springs is agricultural, although the town of Dunnellon is in the watershed (to the west of the spring) and there is even a neighborhood adjacent to the park at the springhead, which is at the end of the run nearest to the top of the photo.
Land use in the Rainbow Springs watershed (https://www.swfwmd.state.fl.us/springs/rainbow/dashboard/)
Rainbow Springs is actually a group of springs that together produce a first magnitude discharge (>100 millions of gallons per day or mgd). Several larger springs (Rainbow 1, Rainbow 4, Rainbow 6, Bubbling Spring) contribute much of the flow, but the run is dotted with smaller vents, some even within the larger springs, visible by their bubbling sand boils (the white area in the photo below). The combined discharge of these vents makes the discharge of my home spring, Volusia Blue Spring, look modest. According to Southwest Florida Water Management District, the discharge was 372 mgd when I was there in January, which is more than 4 times the discharge of Volusia Blue.
One of the many little sand boils along the spring run.
SWFWMD also reported that water clarity was a phenomenal 260 feet when I was there, although apparently it was much lower further downstream where Rainbow Springs becomes the Rainbow River. Given the high nitrate concentrations in the spring (2.6 mg L-1), I am not surprised that water clarity is lower downstream and I am a little surprised that I did not see more algae blanketing the macrophytes. The nitrate concentrations are much lower in Volusia Blue (0.6-1.0 mg L-1) and our efforts to reintroduce eelgrass into the spring have been met with large accumulations of algae–covering the plants, the sediment, floating above the plants, etc. I am a bit puzzled, and pleasantly surprised, to see “clean” macrophytes in Rainbow Springs. I am also slightly puzzled by the fabulous dissolved oxygen concentrations in Rainbow Springs. In Volusia Blue, oxygen concentrations at the boil are 0.1 mg L-1 and barely top 1 mg L-1 when the water reaches the St. Johns River. By contrast, I measured dissolved oxygen concentrations in the 6-7 mg L-1 range, starting at the springhead and continuing on down the center of the channel. The higher concentrations further down are not surprising, given the huge macrophyte beds, but the high concentrations at the headspring, particularly given the high flow rate, were surprising to me. No doubt these are the first of many surprises to be uncovered during my odyssey. It always pays to get out of your box, whatever it may be.
Due to the high water clarity, the videos were very clear, although in many of the videos there is a lot of suspended material even after it seems like it should have settled, more than I expected. In the moving videos, many of the fish are hard to identify beyond “sunfish” because the spring run is deep, much deeper than many of the other springs that I will visit. However, the stationary videos produced very clear images and I was able to identify many species. My first impressions of the fish assemblage of Rainbow Springs were that 1) sunfish really like cameras and 2) there are about 8 million sunfish and 1 million bass in that group of springs (yes, that is hyperbole). Although I cannot really quantify densities of fish from videos, I saw tons of largemouth bass (Micropterus salmoides), both as I was paddling over them and in the stationary videos (half of the stationary videos had at least one, if not several, bass swim through them). I even got some good photos of two bass mating. Interestingly, a lot of the sunfish were spotted sunfish (Lepomis punctatus); this species is a much smaller proportion of the sunfish assemblages in Volusia Blue. I am still working on the videos, so I may pick up a few more species, but I am at 12 now. Not too bad for video only.
A short clip from video taken at the headspring of Rainbow Springs.
A short clip from video taken near the bank of Rainbow Springs run. The orange flagging is on my tripod so that I don’t lose my camera.
Mating largemouth bass (Micropterus salmoides)–it was quite a dance.
Lake chubsucker (Erimyzon sucetta) in the background.
And if you’re ever in Dunnellon, Penn Station has great Cuban food!