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Congrats Haley!

Join us in congratulating the Paerl Lab’s Ph.D. student, Haley Plaas on winning the UNC Graduate School’s 2023 Impact Award!

2023 Impact Awards, 11 headshots

“This year’s Impact Award recipients are creating new knowledge in order to respond to our society’s greatest challenges,” said The Graduate School’s Dean Beth Mayer-Davis. “In a state where the workforce and intellectual ecosystem continues to advance, we need graduate student research to help us continue to prosper. It’s all part of how we serve our state.”

Haley’s research explores the potential threat harmful cyanobacterial blooms pose to human respiratory health and air quality and has accomplished just that. Check out more information on her website! Congratulations Haley!

Neuse River Estuary Conditions – 14 December, 2022

Hi all,

Happy New Year!

Through mid-December river flow continued to be very low. The high salinity record (11.9) that was set at station 0 (Streets Ferry Bridge) in late November was smashed by a 13.4 reading at the bottom on 14 December. The rest of the estuary was really salty too with bottom waters at the mouth near 25. The upper estuary was strongly stratified based on salinity. In the upper estuary (stations 0-30) bottom waters were 3-4 degrees C warmer than surface waters and dissolved oxygen was lowest (~ 4 mg/L) in these warmer, isolated bottom waters. For the rest of the estuary, dissolved oxygen was 8 mg/L or more. Chlorophyll was 10 ug/L or less except near the surface at station 50 where chlorophyll was ~25 ug/L. Microscopic examination revealed the peak in phytoplankton biomass at this station was due to a combination of small cryptophytes and the cool-weather dinoflagellate, Heterocapsa rotundata. These phytoplankton haven’t been associated with fish kills or toxin production. We finally got some rain associated with the strong cold front before Christmas. I imagine that the high salinity upstream of New Bern has probably been pushed downstream. I think we’ll find out next week if the weather cooperates.

Best,

Nathan

Neuse River Estuary Conditions – 29 November, 2022

Hi all,

Overall, river flow during the fall has been very low and high salinity is still firmly in place. On 29 November, salinity still exceeded 20 in the lower parts of the estuary. The estuary was weakly stratified except in the upper estuary where the difference between surface and bottom salinity was approximately 10. At the head of the estuary at Streets Ferry Bridge (station 0), bottom water salinity set an all time ModMon record of 11.95 beating the previous record of 11.27 set in Dec. 2007. Dissolved oxygen was > 8 mg/L except in the highly stratified wates at Streets Ferry Bridge where bottom water dissolved oxygen was ~ 3 mg/L. Chlorophyll was generally less than 10 ug/L throughout the estuary with the exceptoin of a near surface maximum at station 30. Microscopic examination of station 30 surface water revealed a phytoplankton community dominated by the dinoflagellate, Prorocentrum minimum. P. minimum is the most common cool-weather, bloom-forming dinoflagellate in the Neuse. It’s not toxic and hasn’t been associated with fish kills. Turbidity was less than 5 NTU throughout the estuary. The monitoring crew is on the Neuse again today, so we’ll provide one more summary of conditions before the holiday break.

Best,

Nathan

Neuse River Estuary Conditions – 6 Sept, 19 Sept, 6 Oct & 20 Oct, 2022

Hi all,

So far, the second half of hurricane season had done little to end the low flow, high salinity conditions in the Neuse River Estuary.

On Sep 6, surface water salinity at the mouth of the Neuse was 25 and bottom water salinity was about 29. Surface to bottom salinity differences were approximately 5 along the length of the estuary. The upper most stations were not accessible due to the railroad bridge being closed just above New Bern. Water temperatures were very warm, 26-30C. The bottom 2 meters of the water column were hypoxic from the mouth to station 100. The membrane on the dissolved oxygen probe failed after data from station 100 were collected. Phytoplankton biomass was generally less than 10 ug/L chlorophyll a except for a small zone of elevated (20-30 ug/L) chlorophyll a in surface waters and even higher chlorophyll a levels along the bottom from station 30 to station 70. Surface and bottom water samples from station 50 were microscopically examined and revealed that in both the surface and bottom there was a mixed assemblage of cryptophytes, dinoflagellates, diatoms, and a euglena. The euglena was likely the dominant species biomass-wise, followed by the dinoflagellates Levandarina fissa, and Scrippsiella trochoidea. The toxic dinoflagellate, Karlodinium veneficum, was also present, but at concentrations that are unlikely to cause fish kill problems (< 1000/mL). The main diatom was Leptocylindrus minimum.

On 19 September 2022, the salinity regime was similar to that on 6 September but the lower estuary was less stratified. Water temperatures were ~25 C, cooler by 4-5 degrees compared to 6 September. At station 50, high surface water temperatures (~28 C) also coincided with high dissolved oxygen, chlorophyll a, and pH, all conditions indicative of a bloom. I think what we’re seeing here is that high light attenuation caused by a bloom increased the solar warming of the surface layer. Bottom water dissolved oxygen conditions downstream of station 140 were normoxic but hypoxic bottom water conditions extended from station 120 upstream to the tip of the salt wedge above station 20. Bottom waters at stations 20 and 30 were truly anoxic and smelled strongly of hydrogen sulfided. The high turbidity along the halocline at these stations is likely due to the formation of mineral precipitates as dissolved iron forms iron hydroxides when it meets oxygenated waters along the halocline. Microscopic examination of station 50 surface water showed that the bloom was dominated by the same euglena observed on 6 September, the dinoflagellate Levandarina fissa, and the autotrophic ciliate, Myrionecta rubra. None of these are know to produce toxins or cause fish kills.

The Neuse River basin got several inches of rain in late September from Hurricane Ian. The resultant increased river flow decreased salinity a little. Surface salinity near the mouth was still > 20 and the salt wedge still extended upstream of New Bern. An early October cold front significantly cooled the water to less than 20C. Dissolved oxygen conditions were normoxic along the length of the estuary. There were no areas of high (>20 ug/L chlorophyll a) phytoplankton biomass observed. High turbidity (> 20 NTU) was observed at the most upstream station and probably reflects continued moderate river flows after Hurricane Ian.

On 20 October, the tip of the salt wedge extended beyond our sampling stations. Bottom water salinity at station 0 (Streets Ferry Bridge) was 4.6. That’s in the 99th percentile of bottom water salinity at station 0. Despite cool water temperatures (<20 C), hypoxic conditions (< 2mg/L) occurred at stations 20 and 30. A subsurface zone of elevated biomass occurred at ~1 m depth from stations 20 to 50. Examination of surface water from station 20 showed that the community was dominated by Cryptomonas sp. All cryptomonads are generally considered nutritious phytoplankton that rarely cause any kind of habitat/water quality issues.

Take care,

Nathan

Congratulations Dr. Paerl!

Dr. Hans Paerl has recently been selected to receive the National Harmful Algal Bloom Committee Lifetime Research and Service Award! This award will be presented at the upcoming HAB Symposium to formally recognize and honor his research achievements, leadership, and extensive service to the HAB community. We are grateful for his many contributions that have advanced the science of HABs, the outstanding mentorship he has provided to many students and early career scientists, and the many other positive impacts that he has had on the field.

Join us in congratulating Dr. Paerl on this amazing achievement!

California Research – Sept. 2022

The Paerl Lab was back in the Bay Delta, CA last week! Hans Paerl, Leah Nelson, Alex Sabo, and Haley Plaas were working to continue Haley’s dissertation research which focuses on assessing the linkage between nutrient enrichment, phytoplankton community composition, cyanobacterial harmful algal bloom toxin production, and aerosol formation in the Sacramento-San Joaquin River/Bay Delta estuarine ecosystem. This research was accomplished by completing a combination of aerosol measurements and a nutrient addition bioassay experiment.  For this trip, an additional nutrient was added to the bioassay: NH4 and NH4 + P! We will be sure to keep you updated as we analyze the data from these experiments.

Special thanks to all of our collaborators at CA-DWR, USGS, and Restore the Delta (and more)!

   

IE Student Projects Kickoff!

Today the Paerl lab kicked off a third bioassay in collaboration with the Zhao Research Group at NC A&T, which is focused on determining the water quality impacts of landfill leachates (to learn more about this project click here). IE student Meg will be building off of this bioassay for her Independent Research Project and will be determining the effects that these leachates have on algal communities and their composition over an extended period of time. We are looking forward to seeing the results of her project!

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