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Comparison of phytoplankton communities in catfish split-pond aquaculture systems with conventional ponds

Schrader, Kevin K., Tucker, Craig S., Brown, Travis W., Torrans, Eugene L., Whitis, Gregory N.
North American Journal of Aquaculture 2016 v.78 no.4 pp. 384-395
Bacillariophyceae, Chlorophyta, Chrysophyceae, Cryptophyceae, Euglenozoa, Microcystis aeruginosa, Miozoa, Phaeophyceae, Planktothrix agardhii, Planktothrix perornata, ammonia, aquaculture systems, biomass, catfish, chlorophyll, commercial farms, community structure, dissolved oxygen, farmed fish, farmers, fish culture, fish industry, fish waste, phytoplankton, ponds, water flow, water quality, Alabama, Mississippi
There has been a growing interest and use of variations of partitioned aquaculture systems (PAS) in recent years by the southeastern United States of America farmed catfish industry. Split-pond systems, one type of PAS, are designed to better manage fish waste byproducts (e.g., ammonia) and dissolved oxygen levels than the conventional earthen ponds that have been utilized by farmers for many decades. Recent studies have focused on design, water flow rates, and other management areas of catfish split-ponds, but there has so far not been a focused examination of phytoplankton community composition and biomass in these split-ponds. In the current study, pond water samples were collected from split-ponds at a research facility in west Mississippi and at a commercial farm in west Alabama approximately every three weeks during the fish grow-out period (May to November). Water samples were analyzed for chlorophyll a concentration (phytoplankton biomass) of several major phytoplankton divisions and for types of phytoplankton and their abundance. Overall, chlorophyll a concentrations in the split-ponds were maintained within the typical range (0-800 µg/L) found in non-PAS (conventional) catfish ponds. The phytoplankton communities in split-ponds were dominated by cyanobacteria or blue-green algae (Cyanophyta) and by the same common species of cyanobacteria (e.g., Planktothrix agardhii, Planktothrix perornata, Microcystis aeruginosa, Raphidiopsis brookii) reported in previous studies for conventional catfish ponds. In addition, many types of phytoplankton in the other major divisions [Chlorophyta (green algae), Bacillariophyta (diatoms), Chrysophyta (golden brown algae), Cryptophyta (cryptomonads), Euglenophyta (euglenophytes), and Pyrrhophyta (dinoflagellates)] present in the split-ponds were the same as those reported previously in conventional catfish ponds. Therefore, issues related to management practices for pond water quality (e.g., dissolved oxygen) and undesirable cyanobacteria are expected to be similar as those used for conventional ponds.