Geology topics

Research about St. Johns River

Source-linked reports with geographic coverage including St. Johns River.

6 recordsLinked to original sources

USGS2023

Continuous stream discharge, salinity, and associated data collected in the lower St. Johns River and its tributaries, Florida, 2021

The U.S. Army Corps of Engineers, Jacksonville District, is deepening the St. Johns River channel in Jacksonville, Florida, by 7 feet along 13 miles of the river channel beginning at the mouth of the river at the Atlantic Ocean, in order to accommodate larger, fully loaded cargo vessels. The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, monitored stage, discharge, and (or) water temperature and salinity at 26 continuous data collection stations in the St. Johns River and its tributaries. This is the sixth annual report by the U.S. Geological Survey on data collection for the Jacksonville Harbor deepening project. Prior reports in this series documented data collected from October 2015 to September 2020. This report contains information pertinent to data collection during the 2021 water year, from October 2020 to September 2021. There were no modifications this year to the previously installed monitoring network. Data at each station were compared for the length of the project and on a yearly basis to show the annual variability of discharge and salinity in the project area. Discharge and salinity varied widely during the 2021 water year data collection period, which included above-average rainfall for four of the five counties in the study area. Total annual rainfall for all counties ranked third among the annual totals computed for the 6 years considered for this study. Annual mean discharge at Durbin Creek was highest among the tributaries, followed by Trout River, Clapboard Creek, Ortega River, Pottsburg Creek at U.S. 90, Julington Creek, Pottsburg Creek near South Jacksonville, Dunn Creek, Cedar River, and Broward River, whose annual mean discharge was lowest. Annual mean discharge at 7 of the 10 tributary monitoring sites was higher for the 2021 water year than for the 2020 water year, and the computed annual mean flow at Clapboard Creek was the highest over the 6 years considered for this study. The annual mean discharge for each of the main-stem sites was higher for the 2021 water year than for the 2020 water year and ranked second among the annual totals computed for the 6 years considered for this study. Among the tributary sites, annual mean salinity was highest at Clapboard Creek, the site closest to the Atlantic Ocean, and was lowest at Durbin Creek, the site farthest from the ocean. Annual mean salinity data from the main-stem sites on the St. Johns River indicate that salinity decreased with distance upstream from the ocean, which was expected. Relative to annual mean salinity calculated for the 2020 water year, annual mean salinity at all monitoring locations was lower for the 2021 water year except at the tributary site of Durbin Creek, which remained the same. The 2021 annual mean salinity at all sites ranked second lowest since the beginning of the study in 2016 except at Julington Creek and Racy Point, which tied for lowest, and Durbin Creek, which had the same value for each year.

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USGS2022

Continuous stream discharge, salinity, and associated data collected in the lower St. Johns River and its tributaries, Florida, 2020

The U.S. Army Corps of Engineers, Jacksonville District, is deepening the St. Johns River channel in Jacksonville, Florida, from 40 to 47 feet along 13 miles of the river channel beginning at the mouth of the river at the Atlantic Ocean, in order to accommodate larger, fully loaded cargo vessels. The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, monitored stage, discharge, and (or) water temperature and salinity at 26 continuous data collection stations in the St. Johns River and its tributaries. This is the fifth annual report by the U.S. Geological Survey on data collection for the Jacksonville Harbor deepening project. The report contains information pertinent to data collection during the 2020 water year, from October 2019 to September 2020. The addition of water-quality data collection at St. Johns River at Buffalo Bluff near Satsuma was the only modification to the previously installed network. Discharge and salinity varied widely during the data collection period, which included above-average rainfall for 3 of the 5 counties in the study area. Total annual rainfall for all counties ranked third among the annual totals computed for the 5 years considered for this study. Annual mean discharge at Clapboard Creek was highest among the tributaries, followed by Ortega River, Durbin Creek, Pottsburg Creek at U.S. 90, Cedar River, Trout River, Julington Creek, Pottsburg Creek near South Jacksonville, Dunn Creek, and Broward River, whose annual mean was lowest. Annual mean discharge at 8 of the 10 tributary monitoring sites was higher for the 2020 water year than for the 2019 water year, and the computed annual mean flow at Clapboard Creek was the highest over the 5 years considered for this study. The annual mean discharge for each of the main-stem sites was higher for the 2020 water year than for the 2019 water year except for Buffalo Bluff, which remained the same. Among the tributary sites, annual mean salinity was highest at Clapboard Creek, the site closest to the Atlantic Ocean, and was lowest at Durbin Creek, the site farthest from the ocean. Annual mean salinity data from the main-stem sites on the St. Johns River indicate that salinity decreased with distance upstream from the ocean, which was expected. Relative to annual mean salinity calculated for the 2019 water year, annual mean salinity at all monitoring locations was higher for the 2020 water year except at the tributary sites of Trout River, Dunn Creek, and Clapboard Creek, which were lower, and Durbin Creek, which remained the same. The 2020 annual mean salinity on the main-stem of the St. Johns River was the highest since the beginning of the study in 2016 at Dancy Point, Racy Point, Shands Bridge, below Shands Bridge, above Buckman Bridge, and Jacksonville (Acosta Bridge). Among the tributary sites, annual mean salinity rankings for 2020 were highest for Julington Creek and Ortega River, which were the second-highest on record for those sites.

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USGS2018

Continuous stream discharge, salinity, and associated data collected in the lower St. Johns River and its tributaries, Florida, 2016

The U.S. Army Corps of Engineers, Jacksonville District, plans to deepen the St. Johns River channel in Jacksonville, Florida, from 40 to 47 feet along 13 miles of the river channel, beginning at the mouth of the river at the Atlantic Ocean, to accommodate larger, fully loaded cargo vessels. The U.S. Geological Survey installed continuous data-collection stations to monitor discharge, salinity, and associated parameters at 22 sites prior to the commencement of dredging. The U.S. Geological Survey monitored stage and discharge at 13 sites, and water temperature, specific conductance, and salinity at 15 sites; some sites included all parameters. This report contains information pertinent to the data collection sites from their installation date to September 2016, with additional information and data from Hurricane Matthew in October 2016. Site installations began in October 2015; all sites were installed and began collecting data by January 2016. All data available for each site after October 2015 are included in this report. Discharge and salinity ranged widely during the data collection period, which included the effects of Hurricane Hermine in September 2016 and Hurricane Matthew in October 2016. Of the tributaries, annual mean discharge was greatest at Ortega River, followed by Cedar River, Julington Creek, Durbin Creek, and Clapboard Creek. Annual mean salinity for the main-stem sites indicates that salinity decreases with distance upstream, which is expected. The closest tributary site to the Atlantic Ocean (Clapboard Creek) produced the highest annual mean salinity of the tributaries, and Durbin Creek salinity was the lowest of all monitoring locations.

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USGS2014

Experimental West Nile virus infection in Eastern Screech Owls (Megascops asio)

This study evaluated the potential effects of different concentrations of bleached/unbleached kraft mill effluent (B/UKME) on several reproductive endpoints in adult largemouth bass ( Micropterus salmoides ). The kraft mill studied produces a 50/50 mix of bleached/unbleached market pulp with an estimated release of 36 million gal of effluent/day. Bleaching sequences were C 90 d 10 EopHDp and CEHD for softwood (pines) and hardwoods (mainly tupelo, gums, magnolia, and water oaks), respectively. Bass were exposed to different effluent concentrations (0 [controls, exposed to well water], 10, 20, 40, or 80%) for either 28 or 56 days. At the end of each exposure period, fish were euthanized, gonads collected for histological evaluation and determination of gonadosomatic index (GSI), and plasma was analyzed for 17β-estradiol, 11-ketotestosterone, and vitellogenin (VTG). Largemouth bass exposed to B/UKME responded with changes at the biochemical level (decline in sex steroids in both sexes and VTG in females) that were usually translated into tissue/organ-level responses (declines in GSI in both sexes and in ovarian development in females). Although most of these responses occurred after exposing fish to 40% B/UKME concentrations or greater, some were observed after exposures to 20% B/UKME. These threshold concentrations fall within the 60% average yearly concentration of effluent that exists in the stream near the point of discharge (Rice Creek), but are above the <10% effluent concentration present in the St. Johns River. The chemical(s) responsible for such changes as well as their mode(s) of action remain unknown at this time.

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USGS2006

Seasonal variation in habitat use by marsh fishes

We used I-m 2 throw traps to examine habitat use by smallsized fishes within a mosaic of wet prairies and sloughs in the headwaters of the St. Johns River, Florida between August 1992 and November 1995. Estimates of total fish density and biomass varied temporally, but did not differ significantly between habitats. Patterns of habitat use, however, differed among the five numerically dominant species. Bluefin killifish, mosquitofish, and golden topminnows were more abundant in sloughs than in wet prairies. In contrast, Everglades pygmy sunfish were more abundant in wet prairies than in sloughs. Finally, the abundance of least killifish did not differ between habitats. Fish densities were positively correlated with plant biomass (i. e., habitat complexity) and negatively correlated with water depth (i. e., hydrology). Species richness and composition were similar among habitats. However, consistent differences in the relative abundance of numerically dominant species between habitats indicated some degree of habitat-specific assemblage structure. Most species were concentrated into deeper sloughs during drying events. This assemblage of small-sized fishes appears to respond relatively rapidly to changes in habitat structure and hydrologic conditions. We therefore recommend that resource managers consider using fishes as indicator taxa to evaluate the efficacy of ongoing restoration and management efforts in wetland systems.

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USGS2000

Contrasting patterns of habitat use by prawns and crayfish in a headwater marsh of the St. Johns River, Florida

We compared seasonal patterns of habitat use by the prawn Palaemonetes paludosus and the crayfish Procambarus alleni in Blue Cypress Marsh Conservation Area, Florida. Prawn densities were similar to those found in other oligotrophic wetlands of southern Florida, whereas crayfish densities were much greater than reported previously for other wetlands in the area. Prawns and crayfish had strikingly different patterns of habitat use. Prawn density and biomass were similar in wet prairies and sloughs, whereas crayfish density and biomass were significantly higher in wet prairies. Within habitats, the abundance of prawns and crayfish generally increased with increasing structural complexity and the abundance of crayfish generally decreased with increasing water depth. Differences in risk of predation, frequency of agonistic encounters, food availability, and other factors likely contributed to observed patterns of habitat use. Because of differences in their ability to burrow and avoid concentration into dry-season refugia, prawns and crayfish responded very differently to seasonal variation in hydrologic conditions. Prawn densities were initially low (following a severe drought) and then increased during much of the study period, whereas crayfish densities were relatively stable throughout the study period. Overall, it appears that prawns are more responsive to antecedent hydrologic conditions and crayfish are more responsive to the availability of suitable habitats such as wet prairies.

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