Biomass and Productivity of Thalassia testudinum in Estuaries of the Florida Panhandle

Thalassia testudinum often dominates seagrass meadows of the Florida panhandle but few measurements of productivity, biomass, density, turnover or leaf area index in this region have been made. We targeted 5 estuaries located at similar latitudes, 30⁰ ± 0.3⁰N: Big Lagoon, Santa Rosa Sound, St. Andrew Bay, St. Joseph Bay, and St. George Sound. This study was one component of a collaborative partnership of state and local researchers examining factors preventing recovery in panhandle estuarine areas that had historically contained seagrass in the 1940s and 1950s. Measurements were made twice in 2016, once in June and then again in summer or fall, except in Santa Rosa Sound where measurements were made 3 times. In the estuaries sampled for the second time in July or August, aboveground productivity was greater than in June. St. Joseph Bay had the highest aboveground productivity (4.3 g/m2/d) and 1—sided leaf area index (4.2) while St. George Sound had the lowest values (0.41 g/m2/d and 1.0). Principal component analysis suggested that St. Andrew Bay, Big Lagoon and Santa Rosa Sound were the most similar, with higher values for shoot densities and leaf turnover and lower salinities and watershed:water ratios. St. Joseph Bay had high aboveground productivity and salinity, and low turbidity. St. George Sound had low aboveground productivity, high total suspended solids and the highest watershed:water ratio. These baseline productivity estimates will be useful to assess the success of restoration efforts targeting seagrasses in the Florida panhandle and evaluate impacts of climate change on seagrasses

Reproductive Ecology and Phenology of Thalassia testudinum (Hydrocharitaceae) in Tampa Bay, Florida

Successful sexual reproduction and recolonization are critical in maintaining genetic diversity within seagrass meadows. Thalassia testudinum flower, fruit and seedling production were assessed visually at 10 sites within Tampa Bay, Florida approximately every 4 weeks from May to July 2017 to determine if there is spatial and temporal variation in sexual reproductive effort and if location within a meadow effects sexual reproductive effort. Results from this study reveal strong temporal variability throughout the reproductive season. The month of May was observed as peak Thalassia testudinum anthesis and June was peak fruiting in Tampa Bay during 2017. Flower and fruit density ranged from 0.19 ±0.75 to 0.54 ± 1.38 per 0.25m2 and 0 to 0.59±1.550 per 0.25m2, respectively. Highest and lowest flower densities were observed at CK03 and CB02, respectively and highest and lowest fruit densities were observed at CK01 and both CB02 and WD07, respectively. Mean reproductive effort ranged from 0.51±1.82 0.25m2 to 1.92±4.86 0.25m2 with the lowest at JB04 and the highest at EK01. Additionally, results suggest site location, water quality, seagrass density, and localized reproductive variability affect sexual reproductive effort and success. Only 7 seedlings were observed during the survey suggesting that asexual reproduction is the dominant form of meadow growth and expansion in Tampa Bay. These results also suggest that while acreage has reached target goals set forth by the Tampa Bay Estuary Program in the early 1990’s, these meadows have not fully recovered and may be susceptible to natural and anthropogenic stressors

Reproductive Ecology and Phenology of Thalassia testudinum (Hydrocharitaceae) in Tampa Bay, Florida

Successful sexual reproduction and recolonization are critical in maintaining genetic diversity within seagrass meadows. Thalassia testudinum flower, fruit and seedling production were assessed visually at 10 sites within Tampa Bay, Florida approximately every 4 weeks from May to July 2017 to determine if there is spatial and temporal variation in sexual reproductive effort and if location within a meadow effects sexual reproductive effort. Results from this study reveal strong temporal variability throughout the reproductive season. The month of May was observed as peak Thalassia testudinum anthesis and June was peak fruiting in Tampa Bay during 2017. Flower and fruit density ranged from 0.19 ±0.75 to 0.54 ± 1.38 per 0.25m2 and 0 to 0.59±1.550 per 0.25m2, respectively. Highest and lowest flower densities were observed at CK03 and CB02, respectively and highest and lowest fruit densities were observed at CK01 and both CB02 and WD07, respectively. Mean reproductive effort ranged from 0.51±1.82 0.25m2 to 1.92±4.86 0.25m2 with the lowest at JB04 and the highest at EK01. Additionally, results suggest site location, water quality, seagrass density, and localized reproductive variability affect sexual reproductive effort and success. Only 7 seedlings were observed during the survey suggesting that asexual reproduction is the dominant form of meadow growth and expansion in Tampa Bay. These results also suggest that while acreage has reached target goals set forth by the Tampa Bay Estuary Program in the early 1990’s, these meadows have not fully recovered and may be susceptible to natural and anthropogenic stressors

Initial estuarine response to inorganic nutrient inputs from a legacy mining facility adjacent to Tampa Bay, Florida

Legacy mining facilities pose significant risks to aquatic resources. From March 30th to April 9th, 2021, 814 million liters of phosphate mining wastewater and marine dredge water from the Piney Point facility were released into lower Tampa Bay (Florida, USA). This resulted in an estimated addition of 186 metric tons of total nitrogen, exceeding typical annual external nitrogen load estimates to lower Tampa Bay in a matter of days. An initial phytoplankton bloom (non-harmful diatoms) was first observed in April. Filamentous cyanobacteria blooms (Dapis spp.) peaked in June, followed by a bloom of the red tide organism Karenia brevis. Reported fish kills tracked K. brevis concentrations, prompting cleanup of over 1600 metric tons of dead fish. Seagrasses had minimal changes over the study period. By comparing these results to baseline environmental monitoring data, we demonstrate adverse water quality changes in response to abnormally high and rapidly delivered nitrogen loads

Initial estuarine response to inorganic nutrient inputs from a legacy mining facility adjacent to Tampa Bay, Florida

Legacy mining facilities pose significant risks to aquatic resources. From March 30th to April 9th, 2021, 814 million liters of phosphate mining wastewater and marine dredge water from the Piney Point facility were released into lower Tampa Bay (Florida, USA). This resulted in an estimated addition of 186 metric tons of total nitrogen, exceeding typical annual external nitrogen load estimates to lower Tampa Bay in a matter of days. An initial phytoplankton bloom (non-harmful diatoms) was first observed in April. Filamentous cyanobacteria blooms (Dapis spp.) peaked in June, followed by a bloom of the red tide organism Karenia brevis. Reported fish kills tracked K. brevis concentrations, prompting cleanup of over 1600 metric tons of dead fish. Seagrasses had minimal changes over the study period. By comparing these results to baseline environmental monitoring data, we demonstrate adverse water quality changes in response to abnormally high and rapidly delivered nitrogen loads