Today my lab’s first data-driven paper has been published online! It’s called Seasonal Dynamics of Faunal Diversity and Population Ecology in an Estuarine Seagrass Bed and is published in the journal Estuaries and Coasts. The research was led by my first masters student, Micaela Pullen, who graduated with her MSc last year in 2021. In this work, Micaela (with the help of our co-author Derek Gerber and a number of other volunteers!) caught and released all of the small mobile animals she could find using our small push net once a month for one year. We have analyzed the diversity of the animals she caught and how that biodiversity responds to factors such as season, seagrass cover, and fine-scale spatial variables.
Originally, we designed this research project to study the population of wide-bodied pipefish closest to the University of Canterbury. However, we quickly realized that pipefish were not as abundant as we had originally expected! We only caught adult pipefish in summer months, and caught juveniles in the winter. This was really surprising because in other seagrass beds (especially in Australia), this species is hugely abundant (see below for a photo of a pretty female!). Instead, we found lots and lots of juvenile flounder!
Finding flounder in the seagrass habitats wasn’t incredibly surprising, but was very exciting because flounder are an important mahinga kai (traditional food source) for the hapū (local sub-tribe) in this area. The adult flounder are fished from an area closer to the open ocean (our work was conducted in a fairly protected bay), and our results suggest that the seagrass habitat is serving as a really critical nursery ground for this important fish species.
The most common animals we found were shrimp (seen below). The seasonal overall dynamics of all of the species found in the bay tended to be driven by shifts in these two species. Altogether, the patterns of abundance of all animals in the bay (comprising a total of 29 different taxa) was described by the combined effects of seagrass cover, season, and small-scale spatial location. The importance of spatial locations implies that nearby seascape features, such as a rocky reef or freshwater inflow, might be critical in determining which species are found where within the bay.
So although this study started off as an investigation into the population dynamics of pipefish, we were able to learn a lot of important information about the overall community of animals occupying the seagrass bed along the way.
Sarah Flanagan 