The influence of upwelling, coastal currents and water temperature on the distribution of the red tide dinoflagellate, Noctiluca scintillans, along the east coast of Australia

Abstract

Quasi-synoptic surveys along the east coast of Australia between 28 and 34°S show that the heterotrophic dinoflagellate, Noctiluca scintillans, occurs along this entire stretch of the coast. Areas of relatively high abundance of Noctiluca were observed downstream of regions predisposed to currentinduced upwellings as a consequence of alongshore topographic variations. High-resolution temporal and spatial sampling of upwelling events showed that Noctiluca was abundant (up to 28 cells l -1 ) within mature upwelled waters. A high proportion ([80%) of fed Noctiluca cells (cells with prey in their vacuoles) was observed in the mature upwelled waters indicating that the observed increase in abundance of Noctiluca was associated with increased feeding activity. The absolute abundance of Noctiluca in upwelled waters was, however, found to vary from one upwelling location to another and between seasons. In particular, highest abundances of Noctiluca were recorded south of 31.5°S, where the East Australian Current (EAC) characteristically separates from the coast. The high abundances partly arise from southward advection and retention of the Noctiluca cells, and partly from upwelling inshore of the separated EAC driven by cross-shelf boundary layer fluxes. The temperature of the EAC was also found to influence absolute abundances. Surface water temperatures during our summer cruise were anomalously high due to a strong La Niña phase, and up to 4°C warmer than during our spring cruise. We found that the warmer surface water temperatures were associated with relatively lower average abundances of Noctiluca in the near shore zone.

Zooplankton trophic niches respond to different water types of the western Tasman Sea: A stable isotope analysis

“…Satellite images also indicated persistent upwelling occurring in the area prior to sampling. Correspondingly, we observed high abundances of the dinoflagellate Noctiluca scintillans in the IS water type (Henschke, unpublished data), which has been associated with upwelling events (Dela-Cruz et al, 2008).…”

Zooplankton assemblages as indicators of seasonal changes in water masses in the boundary waters between the East China Sea and the Taiwan Strait

“…The present study shows that appendicularians and N. scintillans are associated mainly with the coastal waters of Taiwan (St1 and St2) in March, a period for which they could act as good indicators (IndVal [25%). N. scintillans is particularly known for its association with coastal waters (Kâ & Hwang, 2011) and upwelling areas (Dela-Cruz et al, 2008).…”

Distinct cross-shelf gradient in mesophotic reef fish assemblages in subtropical eastern Australia

“…Individuals were identified to the finest level of taxonomic classification possible using standard and locally relevant guides, principally Kuiter (1996), Allen et al (2003), Allen (2009), and Davie et al (2011) as well as online sources www. fishbase.org and http://australianmuseum.…”

“…In other meso photic ecosystems throughout the world, reported shifts from herbivory to carnivory (especially plankti vory; Kahng et al 2010) with depth, even where edible macroalgae is abundant (Garcia-Sais 2010), suggest that other factors are at play. In the local context, these could include localised shelf-break up wellings (Baird et al 2006, Dela-Cruz et al 2008, Marin 2013 or fishing pressure (Richmond & Stevens 2014).…”