Owen Silvera (pictured bottom-center) together with his analysis group at Lake Okeechobee. Picture by Owen Silvera.
Within the early mornings and late nights, from dawn to sunset, graduate pupil Owen Silvera and his colleagues launched into numerous expeditions in Lake Okeechobee.
“I recall spending whole days there, targeted on gathering sediment in hopes to disclose deeper truths in regards to the chemistry that drives algal blooms, the predominant concern of Lake Okeechobee. We labored tirelessly on these days, in our boat; generally in areas of nationwide intrigue reminiscent of Pahokee marina, simply ten toes from shore, which has so typically been the middle of protection on algal blooms by the media” says Silvera.
Nonetheless, Lake Okeechobee is an enormous water physique which Silvera provides scale to by it being bigger than Nassau, Bahamas, the island of his beginning. Alongside the Geochemistry and Geochemical Sensing Laboratory at FAU, he has collected sediment from each attain of the Lake. Researching the sediments tells a narrative that extends past the mere process at hand, providing a glimpse into a bigger narrative that unfolds throughout Florida’s largest lake, Lake Okeechobee, regarding dangerous algal blooms.
Whereas dangerous algal blooms and nutrient dynamics are sometimes related to direct runoff from stormwater, sediments additionally play a big function. Owen Silvera’s analysis journey, supported by the Aylesworth Scholarship, has offered him with the assist to check the interaction between sediments, dangerous algal blooms (HABs), and water high quality in huge shallow lakes like Lake Okeechobee.
“I’m obsessed with conducting analysis that immediately impacts the financial system, reminiscent of dangerous algal blooms which might set off states of emergency. This facet of my work resonates deeply with me as a result of I attempt for tangible outcomes that positively have an effect on individuals’s lives,” says Silvera.
Blue-green algae at marina situated on Lake Okeechobee. Picture by Owen Silvera.
“Sediments play a pivotal function in ecosystem dynamics. In Lake Okeechobee, characterised by its shallow depth and susceptibility to robust winds, sediment resuspension emerges as a big phenomenon that swiftly introduces vitamins into the water column that may affect algal blooms.”
Sediment resuspension is the method by which small particles of rock from the bottom or settled on the backside of a physique of water are stirred up and introduced again into the water column by wave motion, currents, or turbulence, in addition to human actions like dredging or boating may end up in suspension. Despite the fact that Lake Okeechobee stands as a case research, this analysis is relevant all through Florida.
“In Florida, we’ve got a variety of shallow lakes. When massive winds decide up, there could also be no wind blockage over the entire course of those lakes, driving waves and sooner currents. Since these lakes are shallow, sediments are very near the floor and there’s not a lot area for that vitality to dissipate, and so the sediments are simply resuspended,” says Silvera.
Specific considerations are the vitamins inside sediments, notably nitrogen and phosphorus. Whereas algae predominantly depend on these parts, sediments harbor extra substances like metals, with iron additionally being a focus of Owen’s analysis. The resuspension course of exacerbates nutrient masses and imbalances, which might probably immediately affect the bloom of species reminiscent of microcystin-producing blue-green algae.
“From this analysis, we see that the sediments which are in suspension from Lake Okeechobee particularly have an effect on the a great deal of nitrogen and phosphorus which are going to the coasts. Certainly, new analysis exhibits that nitrogen from Lake Okeechobee launched into the Caloosahatchee, is linked to even the purple tide algal blooms within the Gulf of Mexico.”
Silvera assessing collected sediments within the lab. Picture by Owen Silvera.
Fieldwork Brings Native Views and Observations to Dangerous Algal Blooms
“In 2021, the Pahokee Marina made a number of nationwide headlines resulting from extreme blue-green algal blooms. Quick ahead to now, and we discover ourselves conducting our work amidst the robust odor emitted by the blue-green algae, which is notoriously foul-smelling. And these are the identical waters that individuals are fishing in. We’re seeing these impacts firsthand on the setting and group,” says Silvera.
Silvera and his analysis group employs a mixture of monitoring and experimental approaches to look at sediment and nutrient dynamics. Area expeditions sometimes contain water sampling and sediment assortment, whereas laboratory simulations of resuspension occasions assist us management and higher perceive nutrient dynamics throughout such occasions.
“Through the wintertime and spring, you get actually excessive winds over Lake Okeechobee, which restrict algal blooms. Despite the fact that there’s a lot sediment within the water column loaded with vitamins, the algae can’t make use of those vitamins when they’re restricted by gentle. Nonetheless, within the summertime, when issues begin to settle out of the water column, the vitamins that stay are then slowly taken up by algae, they usually bloom just about each summer season. Specifically, we research sediment-water interactions to watch the circumstances which promote intense algal blooms of probably poisonous species as a result of there are nonetheless many unknowns which we will probably mitigate towards with higher data.”
Hurricanes are only one instance of a climate occasion once we would possibly count on sediments to be resuspended. The main focus round such excessive climate occasions has primarily been on total modifications in total water high quality. Nonetheless, land drainage and sediment resuspension act collectively to extend the whole nutrient load, i.e., suspended within the water column. Owen’s analysis separates the complexity of combined inputs related to pure storm occasions and highlights the precise detriment of sediment inputs. Furthermore, all of those vitamins are then funneled in the direction of the Atlantic Ocean and Gulf of Mexico throughout launch intervals. This water passes by the St. Lucie and Caloosahatchee estuaries, carrying with it at sure occasions poisonous algae, however at all times natural sediment to repeat cycles of eutrophication far past the central state lakes and agricultural watersheds.