A survey of meiofaunal communities in beaches of Victoria, B.C.
Date
2021
Authors
Dundas, Amanda
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Abstract
Meiofauna are an understudied category of beach biodiversity worldwide, even though they are highly abundant. Factors that control the distribution of meiofauna, such as those related to sediment characteristics, are unclear. This study aimed to categorize the abundance and taxonomical diversity of meiofauna, the median grain size (Q50), the sediment sorting coefficient (Q25/Q75), and the organic matter content at 18 beaches in Victoria, B.C. It also investigated if those characteristics differed between two beach types, muddy and sandy, and whether meiofauna abundance was correlated with sediment characteristics. To test the hypothesis that meiofauna would be more highly abundant in fine sediment beaches (mudflats) than in coarse sediment beaches (sandy beaches), nine mudflats and nine sandy beaches were chosen based on visual inspection of the sediment. Then, sediment cores and meiofauna samples were taken at each of the 18 different beaches. Sediment size was determined using sieving, and organic matter of the sediment was quantified using loss on ignition. Meiofauna were enumerated and quantified using microscopy. The data were analyzed using two-sided t-tests and regression analyses. Meiofauna were found to be extremely abundant (on average 835 animals per 15cc of sediment) across all sample beaches. Median sediment size and sediment sorting (heterogeneity) did not vary significantly between muddy and sandy beaches, although the overall trends were in line with the prediction that muddier beaches had lower median particle size and higher sediment heterogeneity than sandy beaches. Organic matter was significantly higher in mudflats compared to sandy beaches. Meiofaunal abundance and total number of taxa were not significantly different among the beach types, and were not correlated with sediment characteristics. Based on my study I make several recommendations for future sampling programs. More research, especially time-series data collection, is needed to understand variation in these communities, as it is difficult to observe patterns from a single time point. My results illustrate how vast meiofaunal communities are (millions per square meter), yet how little we understand them. As the world changes, it is important to understand all aspects of beach biodiversity, and these tiny animals account for most of the non-microbiotic portion of it.