A couple of weeks without rain and the estuary is looking almost normal. The salt wedge is at New Bern and surface water salinity near the mouth was about 10. Most of the estuary was strongly stratified and bottom waters were hypoxic from stations 60 to 160. There was a peak in DO at station 50 that was likely due to high phytoplankton production. Microscopic observation of the station 50 surface sample showed a high concentration of small (3-5 um) centric diatoms. Chlorophyll data are not shown due to a failed probe. During the previous trip on 7 May, the chlorophyll probe of the YSI data sonde started to malfunction but the malfunction was not noticed until this trip on 21 May 2019. The bloom level chlorophyll a concentrations observed at station 50 on 7 were an artifact of this malfunction. The probe has been replaced and in vivo chlorophyll a data from both dates have been flagged in the data set.
A fish kill was observed a few days following this trip on 21 May, but no dead fish were noticed during a boat run from New Bern to station 100 on yesterday, 28 May. Based on the reports that I saw, the dead fish were mostly menhaden and had sores consistent with ulcerative mycosis caused by Aphanomyces invadans. This fungus is most virulent when salinities are low and temperatures are in the low to mid 20’s C; conditions observed during the fish kill. Fish that are already stressed, e.g. due to hypoxia, are more likely to suffer from the infection. I’ve attached a couple good papers for those interested.
Kiryu et al. 2002-induction of menhaden ulcers by exposure
Oidtmann 2011-review of A invandans
New and improved, more compact and portable water quality instruments , built by Tony Whipple of the Leuttich Lab are being installed on the M.V. Neuse, allowing for easier transfer from ferries.
This would not be possible without help from our friends at NCDOT ferry division. David Griffin and John Destefano were instrumental in getting things connected.
The M.V. Neuse, appropriately named, is currently crossing the Neuse River from Cherry Branch to Minnesott Beach.
Stay tuned for updates on the FerryMon Page as to when this system is up and running. https://paerllab.web.unc.edu/projects/ferrymon/
David “Sparky”, John and Tony
The water quality analysis system
I’m an environmental science major heading into my senior year at UNC Chapel Hill. I have minors in Marine Science and Chinese. I have participated in conservation-related field work throughout my undergraduate career, beginning with a summer of ecology research at the Flathead Lake Biological Station in Glacier National Park, followed by 7 months of renewable energy research in Thailand, and most recently, during my semester at UNC IMS carrying out research for my senior honors thesis. I will be continuing this research at IMS with the help of the Mary and Watts Hill Student Internship Fund. Through this work, I hope to determine a relationship between harmful algal bloom formation and changes to salinity in the estuaries of coastal North Carolina, in light of climate change-driven changes to hydrologic event patterns. Thanks to funding and support from the Mary and Watts Hill Fund, I can continue to pursue my passion and develop my understanding of the natural world for a future career in sustainability.
The Neuse is an estuary again, a strongly salinity, stratified estuary with hypoxic bottom waters. The hypoxic zone stretched from just downstream of New Bern to the mouth. A zone of high chlorophyll with a subsurface maximum at ~1 m depth was detected from stations 20 to 70. Microscopic examination of surface waters from station 50 revealed a community dominated by freshwater diatoms, primarily Aulacoseira.
Until the next trip,