Charged with developing a long-term HAB monitoring program for the SC’s estuaries, the SCHABP plans initially targeted tidal creeks and open estuaries.  We found one widespread HAB type in these systems, mostly in the upper tidal creeks.  It has been tabbed the “SC red tide” based on the dark reddish orange color produced by dense blooms of the organism.  Molecular and morphological research has indicated that these blooms are formed by at least two dinoflagellate species, Kryptoperidinium foliaceum and Scrippsiella sp. (which may be a new species), which on occasion co-occur.  Given its widespread distribution, the possibility that these blooms were not prevalent in the past, and the demonstrations that K. foliaceum blooms cause shellfish stress effects, SCHABP research efforts on this phenomenon are significant.  Besides this species, only one other HAB type has been detected in these estuarine systems.  Recently (29 April 2003), an extensive bloom of Heterosigma akashiwo (105 cell ml-1) occurred in Bulls Bay that extended 4-5 miles offshore (see below).  This 80 square mile bloom, which apparently originated from inside the Bay, was the first of such magnitude in SC, to our knowledge.  The cyst bed required to fuel that bloom must have been dense and/or extensive.  

Brackish lagoonal ponds were not originally included in the SCHABP sampling design, but since spring of 2001, these systems (largely stormwater detention or retention ponds) have required much of the Program’s research attention.  Whereas nuisance blooms, one category of HAB that causes water discoloration and odors, are a well-known byproduct of detention ponds, blooms that can produce toxins are rarely reported from these waters.  The SCHABP sampling plan extended to detention ponds when a Pfiesteria-related fish kill in a Hilton Head subdivision pond was followed by dense blooms of several other potentially toxic species in this and Kiawah ponds throughout the spring of 2001.  Over the last 3 years, we have found an unprecedented density and prevalence of HABs in SC detention ponds.
 
For the purposes of organizing personnel tasks and sampling logistics, we tend to distinguish tidal creek/open estuary events from those that occur in lagoonal ponds.  However, we are finding a strong interconnectivity in HAB dynamics between all SC brackish systems.  For example, in a Charleston brackish subdivision pond, Richardson et al. (2002) found high Scrippsiella sp.abundances associated with the flooding tide that led to nighttime oxygen depletion and a fish kill.  They concluded that although this species is known to form “red tides” in tidal creeks, it can also be brought into lagoonal ponds in high numbers.  Also, tidal creek blooms of Kryptoperidinium foliaceum have been associated with organic-rich runoff events (Lewitus et al. 2001) and this species also is prevalent in tidal creeks bordering ponds (Lewitus and Holland 2003, Lewitus et al. 2003).  A reasonable question is whether processing of DOM by HABs within the ponds increases the lability of the DOM pool for use by Kryptoperidinium (on ebbing tide).  Also importantly, on many occasions, we found an association between HABs within the ponds with lower but significant abundances of the same species in adjacent tidal creeks (Lewitus et al. 2003, subm.).  This information begs an important question – how far and to what extent do repetitive, dense blooms in brackish ponds influence fishes, shellfishes, and ecosystems in tidal creeks and open estuaries?  Because HABs in SC brackish ponds have been linked to eutrophication (Kempton et al. 2002, Lewitus and Holland 2003, Lewitus 2003, Lewitus et al. 2003, subm.), this question has implications to the potential effect of SC coastal zone development on promoting tidal creek HABs.  

The SCHABP has documented many different types of HABs, has advanced understanding of the causes and impacts of the individual types, and is now evolving toward a more holistic understanding of the interrelationship of these blooms across all SC estuarine systems.