Dr. Ryan Paerl (NCSU) utilized environmental ModMon data to show that extreme weather events, such as hurricanes and increased precipitation, affect both the amount and the composition of picophytoplankton in the Neuse River Estuary. The Science Daily article can be found here
Need a riveting read this weekend? Please check out the newest publication from the Paerl lab! (link below)
Plaas and Paerl ES&T cyanotoxin review
Dr. Paerl & Haley Plaas (PhD candidate) worked with collaborators in UNC’s visual communications master’s program to create this video explaining the importance of CyanoHAB research. Haley’s work in the Paerl lab at UNC-IMS will work towards preventing the expansion of harmful algal blooms to protect people, pets, wildlife, and our environment.
Dr. Paerl presented the keynote address, “Mitigating harmful cyanobacterial blooms in a hotter, hydrologically more-extreme world,” for the 2019 Winona B. Vernberg Distinguished Lecture Series on Wednesday, November 13, 2019. Dr. Paerl discussed the importance of continued research of harmful algal bloom management on the Neuse River with environmental health and fisheries management staff as well as academics from North and South Carolina at an invited seminar at the University of South Carolina.
Check out the YouTube video linked above to watch the full presentation
The fish kill that started in late September was still occurring on 27 October. Dying and dead peanut sized (~3″) menhaden were observed from station 70 to station 100. This area seems to be where most of the fish kill activity has been observed. Many of the fish had sores consistent with infection by the water mold, Aphanomyces invadans. In the fish kill zone, water temperatures near 20C and salinities of 5 or less are optimal for growth of A. invadans.
The estuary was highly stratified from New Bern to station 160 and hypoxic bottom waters extended downstream to station 160. Anoxic conditions, indicated by the smell of sulfide, occurred at station 50 through 100. Anoxia is unusual but occasionally occurs during the hottest, calmest periods of the summer when there is moderately high river flow. I don’t recall ever seeing anoxic conditions this late in the season. High chlorophyll a levels were observed near the surface from stations 60 to 160.
Surface waters from station 70 were observed microscopically. The bloom was primarily dominated by the dinoflagellate Gyrodinium instriatum which is not known to be toxic or cause fish kills. Lesser cell densities of the potentially harmful raphidophyte, Heterosigma akashiwo, were also observed. While Heterosigma akashiwo has been repeatedly associated with fish kills in other estuaries, this fall is the first time I am aware of that it has been associated with a fish kill in NC waters. I strongly caution that this association does not imply that H. akashiwo was responsible for the fish kills.
State funding for ModMon has expired. ModMon monitoring activities and these associated reports will be suspended while we pursue other funding options.
Last Friday, the Paerl Lab gathered together to carve some pumpkins and taste some yummy fall foods such as smoked pecans, apple cake, apple cider donuts, and candy corn!
Our crew was out Tuesday, 13 October 2020. The estuary was stratified with pockets of hypoxic water observed near New Bern at station 30 and near the bend at stations 100 and 120. The fluorescence probe that measures chl-a failed mid-cast at station 140 and all chl-a data upstream of 140 was removed due to meaningless, negative values. A bloom at station 70, however, was indicated by the high near surface DO, observation of brown water color, and clogging of filters back in the lab. The crew observed fish actively dying south of Fairfield Harbor (our station 70) and fish dead on the surface from there to mid-channel north of Slocum Cr. (our station 100). The dominant species in the bloom, the dinoflagellate Gyrodinium instriatum aka Levanderina fissa) is not known to be toxic. G. instriatum is the most common bloom former in the Neuse during the summer and early fall and hasn’t previously been associated with a fish kill. This fish kill appears to have been ongoing since 30 September.
I’m playing catch up again.
Conditions on 18 August were about as stratified as they get in the Neuse. From New Bern to the mouth bottom water salinities were more than 10 ppt greater than at the surface. The pycnocline increased in depth from about 2 meters at New Bern to 5 m at the mouth, and waters below the pycnocline were hypoxic/anoxic along that whole stretch. Overall, chl-a levels were low but there was a broad zone of moderate 10-20 ug/L at the surface that extended from station 60 to station 140. A subsurface, thin layer of chl-a > 40 ug/L was observed at station 70. (image below)
After ~20 kt winds from 14-15 Sep. and continued ~15 kt winds on 16 Sep, the estuary was much more mixed on 16 Sep. There were pockets of stratification and hypoxia near New Bern and near the bend at stations 100 and 120. These pockets of hypoxia were associated with waters that were warmer than surface waters and saltier than downstream bottom waters. It’s not unusual for bottom waters to be warmer than surface waters during the fall as the surface loses heat to a cooling atmosphere. It is weird to see higher salinity upstream, and may reflect cross channel variability that isn’t being captured by our down-channel transect. Chl-a was moderate (10-20 ug/L) from New Bern to the mouth. (image below)
On Monday 28 Sep, the estuary was highly stratified again. Bottom waters were 2 mg/L or less from New Bern to about station 70 and were ~4 or less from station 70 to the mouth. A broad zone of elevated surface chl-a was observed from station 60 to station 140, with a surface maximum of ~40 ug/L at station 100. Downstream of station 100, maximum biomass occurred as a subsurface maximum at 1 to 2 m depth. Two days later on 30 Sep., a fish kill was reported on Flanners Beach. Water from the location of the kill contained high concentrations of the potentially harmful raphidophyte species, Heterosigma akashiwo. Microscopic observation of surface water from station 100 contained very few Heterosigma akashiwo cells. The community was primarily cryptophytes, dinoflagellates, and small diatoms that are typical for this time of year and not known to harm fish. During an unrelated sampling trip on 2 Oct., I observed an ongoing fish kill near the mouth of Slocum Cr. There was a mix of actively dying and menhaden that had been dead for a day or two. I microscopically examined water samples collected from the fish kill area and from the Neuse outside the fish kill area. Low concentrations of Heterosigma akashiwo were present but the low observed concentrations have not been previously related to fish kills. (image below)
Dr. Paerl was invited to publish in J. Phycol. and provide his perspective on US-China collaborative work on CyanoHABs
Click Here for the full article