The Tenth State of the River Report is a summary and analysis of the health of the Lower St. Johns River Basin (LSJRB) available at http://www.sjrreport.com. The Report addresses four main areas of river health: water quality; fisheries; aquatic life; and contaminants. This year’s Report includes a special section on ten-year summaries of all indicators. As noted below, over the last ten years, some indicators have improved, others have worsened, and still others have remained unchanged.
The trends of some indicators have improved:
- Total nitrogen levels in the mainstem and tributaries have declined.
- Total phosphorus levels in the mainstem and tributaries have declined.
- Dissolved oxygen levels in the mainstem are improving.
- Conditions for three critical wildlife species have shown improvement: the bald eagle, the wood stork, and the Florida manatee.
The trends of some indicators have worsened:
- Salinity has gradually risen over the last two decades and is expected to continue its increase, with increasing potential negative impacts on submerged aquatic vegetation and the aquatic life that depends upon it.
- Nonnative species increased from 56 total species in 2008 to 80 in 2017, and the spread of lionfish and Cuban treefrogs is of particular concern due to their impacts on the native ecosystem.
- Wetlands continue to be lost to development pressures.
The trends of many indicators are unchanged:
- Dissolved oxygen levels in the tributaries have remained unsatisfactory and have not shown improvement.
- Chlorophyll a, an indicator of harmful algal blooms, has not decreased in the ten-year timeframe and shows no indication of decreasing soon.
- Fecal coliform levels remain significantly above water quality criteria in many tributaries.
- Submerged aquatic vegetation has experienced some very recent regrowth due to rainfall, but the long-term trend is uncertain.
- Most finfish and invertebrate species are not in danger of overfishing, with the exception of channel and white catfish, which both have the potential to be overfished in the near future.
This year’s Report contains a Highlight section on bottlenose dolphin inhabitance of the St. Johns River. Dolphins in the river have been the subject of greater research efforts since a spike in dolphin deaths during the summer of 2010 resulted in federal declaration of an Unusual Mortality Event. The event was co-associated with an upriver algal bloom, fish kill, and an intensive dredging project near downtown Jacksonville. Dolphins in the SJR were also affected by a viral illness that spread along the U.S. Atlantic seaboard in 2013-2015. Abundance estimates of dolphins in the SJR ranged from some 74 individuals in the winter of 2014 to some 203 dolphins in the summers of 2011 and 2013. Approximately 50% of these individuals use the SJR year-round. Dolphins regularly use areas further upriver than past recognized, as much as 35 miles from the SJR mouth. Threats to SJR dolphins include fishery gear/crab trap line entanglement, boat collisions, disturbance of habitant important for dolphin breeding and feeding activities.
The full Report provides an in-depth look at many aspects of the LSJRB. Section 1 provides an overview of the Report and the basin and describes the basin’s landscape, human occupancy, and environmental management spanning the 1800s to early 2016. Section 2 describes water quality in terms of dissolved oxygen, nutrients, algal blooms, turbidity, fecal coliform, tributaries, and salinity. Section 3 addresses the state of the river’s finfish and invertebrate fisheries. Section 4 examines the condition of aquatic life, encompassing plants, animals, and wetlands. Section 5 discusses conditions and importance of contaminants in the LSJRB. These contaminants include air and water emissions of chemicals in the LSJRB, as reported to EPA Toxics Release Inventory; mercury, the subject of a statewide reduction effort; metals, in both sediments and the water column; polycyclic aromatic hydrocarbons; polychlorinated biphenyls; and pesticides.