Abstract:
Relatively few studies have been undertaken on the abundance and diversity of benthic macro-faunal species, and the environmental factors influencing the distribution of macrofaunal assemblages in the temperate mangrove forests in New Zealand (Alfaro, 2006; Alfaro, 2010; Ellis et al., 2004; Morrisey et al., 2003, Morrisey et al., 2007; Stokes et al., 2009; Townsend et al., 2010). Existing studies indicate that the abundance and diversity of species within mangrove forests are relatively low compared to adjacent estuarine habitats, and that there are no distinct macro-faunal assemblages, specifically restricted to mangrove forests (Alfaro, 2006; Alfaro, 2010; Ellis et al., 2004; Morrisey et al., 2003; Morrisey et al., 2007; Stokes et al., 2009). The aim of this thesis was to investigate the benthic macro-faunal diversity of a mangrove forest, and to identify what environmental variables were influencing the abundance and distribution of the macro-benthic community along the gradient of increasing elevation within the mangrove forest in Whangateau Harbour, northern New Zealand. Three transects ran from the sea towards the land so as to capture different environmental characteristics and community composition along the gradient of increasing elevation within the mangrove forest. There were 20 sampling locations per transect. At each sampling location a 0.25 x 0.25 m2 quadrat was randomly placed on the ground and a core sample was taken. A range of environmental variables and the presence of benthic epifauna and infauna in the quadrat and core were recorded. This was repeated three times at each sampling location. This amounted to 180 samples in total. A principal component ordination was constructed to summarise the environmental data. Multi-dimensional scaling ordinations were constructed to show the composition and distribution of the benthic communities and their correlation with the environmental data. The abundance and diversity of taxa decreased with increasing elevation and distance into the mangrove forest. Sediment grain-size was the main environmental factor influencing the abundance and diversity of the benthic macro-faunal communities along the gradient of increasing elevation. These findings provide direction for future studies and contribute to the current understanding of environmental factors influencing New Zealand temperate mangrove forest macro-faunal diversity.