Opportunistic Species and Seasonal Variation in Epiphytic Foraminiferal Assemblages in Abalone Farm Nets

Abstract

Monitoring of dissolved oxygen (DO), temperature, and epiphytic foraminifera on seagrass in the nets of abalone farms in three areas (Haenam, Pyeongildo, Soando) with different seawater movement was conducted between April 2016 and January 2017. The aim was to identify the opportunistic species, seasonal variation, relationships with DO, and temperature of epiphytic foraminiferal assemblages under environmental conditions affected by the biodeposits discharged from abalone farming. The results showed that the highest relative abundance of epiphytic foraminifera occurred in September (22.96 degrees C), although the temperature was highest in August (24.37 degrees C); this may be related to the consistently stable high temperatures during this time (22-23 degrees C). There was no direct relationship between DO and epiphytic foraminiferal assemblages. Rosalina bradyi (frequency: 78.6%; species diversity: 0.96; distributed across three areas in July) was found to be an opportunistic species for nutrient enrichment discharged from abalone farming. Epiphytic foraminiferal assemblages of the three areas were varied, from the R. bradyi assemblage in July, to the R. bradyi-Cornuspira involvens or R. bradyi-Murrayinella minuta assemblages in August and September, and to the Glabratella sp.-R. bradyi or Epistominella naraensis-R. bradyi assemblages of January. Species diversity was also increased. It is thought that this seasonal variation in epiphytic foraminiferal assemblages may be a process needed to maintain a stable epibiosis in epiphytic foraminifera.