The effect of a climatically-induced wet phase on the meiofaunal community of the St Lucia Estuary, South Africa

Following a decade long drought with hypersaline conditions, the St Lucia Estuary moved into a two year wet phase. The wet phase began with higher than average rainfall that lowered salinities throughout the system.... [ view full abstract ]

Following a decade long drought with hypersaline conditions, the St Lucia Estuary moved into a two year wet phase. The wet phase began with higher than average rainfall that lowered salinities throughout the system. Environmental data and meiofauna samples were collected from five representative sites along the estuary during quarterly surveys conducted in each season. Diversity indices suggest that 2011 experienced a generally greater meiofaunal density, taxon richness and diversity, when compared to 2012. Community analyses revealed that meiofaunal communities differed between sites and seasons as a result of the estuarine gradient and seasonal variation in environmental parameters. The initial meiofaunal communities showed no distinction based on spatial or temporal differences. However, the increase in similarity of communities in 2012 is indicative of a distinction between sites that was generally absent in 2011. Sites along the estuary tended to increase in similarity over time with a greater level of homogeneity in 2012, suggesting that communities are becoming more established within this phase. The transitional state in which these communities were studied suggests the possibility of a lag time for any change to become evident and may be the result of the drastic change that the system experienced, as the lakes filled and the system was once again connected. The overall meiofaunal dynamics during the two year wet phase were variable, but appear to show potential long term improvement