NORTH MYRTLE BEACH, S.C. — Experts at Coastal Carolina University said they think they know why a lot of dead fish washed up along the coastline of North Myrtle Beach on Sept. 11, WPDE reported.
The dead menhaden fish were associated with a period of low dissolved oxygen and salinity, according to Susan Libes and Danielle Viso of the Burroughs & Chapin Center for Marine & Wetland Studies at CCU.
The city of North Myrtle Beach posted data collected on Facebook of possible factors leading to the fish dying:
- A typical summertime episode of low dissolved oxygen (< 4 mg/L) occurred from Sept. 10 to Sept. 11, with very brief periods of hypoxia, a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. This coincided with very brief periods of upwelling and favorable southwesterly winds. Wind speeds were consistently low (< 10 mph) on both days.
- The unusual occurrence of low salinity water at Cherry Grove also played a part. This started Sept. 9 and persisted, despite the lack of local rainfall. From Sept. 5 onward, winds have been mostly out of the north. This has likely set up a southbound longshore current, bringing fresher waters from Hog Inlet, Lockwood Folly,and/or the Cape Fear River to the Grand Strand. Also, significant rain fell inland from Sept. 8 to Sept. 11, totaling close to 2 inches. The low-salinity water reached Apache Pier on Sept. 12. The USGS sensor in the waterway suggests significant freshwater was discharging from Aug. 22 to Sept. 6.
- An algal bloom was detected in the bottom waters at both piers from Sept. 8 to Sept. 11.
Experts said that fish kills can happen due to a sustained period of very low oxygen that fish cannot survive. They said the algae bloom could have also played a part in the low dissolved oxygen.
The southbound current could have also brought in freshwater that gave nutrients, encouraging the algae bloom, according to experts.
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