Mesozooplankton community associations with water mass and season off the Southeast coast of New Zealand (2017–2018)

ABSTRACT Zooplankton community structure varies among distinct water masses and can be highly temporally dynamic, with patterns reflecting seasonal, interannual, and decadal changes in food webs. The seasonal dynamics of zooplankton communities in waters east of the Otago peninsula (New Zealand), and their associations to the region’s water masses, have not been investigated in detail since the 1960s. The current study was conducted along the Munida Time Series Transect, a 65‐km transect that runs perpendicular to the coast. The transect crosses four distinct water masses: Neritic, Subtropical, Subtropical frontal zone, and Sub Antarctic waters, all with distinct temperature, salinity, and nutrient characteristics. Samples were taken from the epipelagic (<200 m) along 8 stations every 2 months between November 2017 to September 2018, which coincided with a strong marine heatwave in January 2018. We found significant differences in community distributions of zooplankton both among water masses and seasons. Biomass dominants were typically copepods, but other groups – such as appendicularians or thecosome pteropods – dominated at certain times or locations. These results provide the first detailed records of zooplankton distribution in this complex oceanographic region in 50 years and highlight the importance of monitoring zooplankton in dynamic locations in the face of climate change.