Chlorophyll-a and Sea Surface Temperature Changes in Relation to Paralytic Shellfish Toxin Production off the East Coast of Tasmania, Australia

Abstract

Toxic phytoplankton have been detrimental to the fishing and aquaculture industry on the east coast of Tasmania, causing millions of dollars in loss due to contaminated seafood. In 2012–2017, shellfish stocks were poisoned by Alexandrium catenella, a dinoflagellate species that produces paralytic shellfish toxins (PST). Remote sensing data may provide an environmental context for the drivers of PST events in Tasmania. We conducted spatial and temporal trend analyses of the Multi-Scale Ultra-High-Resolution Sea Surface Temperature (MUR SST) and Ocean Color Climate Change Initiative chlorophyll-a (OC-CCI chl-a) to determine if SST and chl-a correlated with the major toxin increases from 2012 to 2017. Along with the trends, we compare the remotely sensed oceanographic parameters of SST and chl-a to toxin events off the east coast of Tasmania to provide environmental context for the high-toxin period. Spatial and temporal changes for chl-a differ based on the north, central, and southeast coast of Tasmania. For sites in the north, chl-a was 5.3% higher from the pre-PST period relative to the PST period, 5.1% along the central part of the coast, and by 6.0% in the south based on deviations from the coastal study area time series. Overall, SST has slightly decreased from 2007 to 2020 (tau = −0.011, p = 0.827) and chl-a has significantly decreased for the east coast (tau = −0.164, p = 1.58 × 10−3). A negative relationship of SST and PST values occurred in the north (r = −0.530, p = 5.32 × 10−5) and central sites (r = −0.225, p = 0.157). The correlation between satellite chl-a (from OC-CCI, Visible Infrared Imaging Radiometer Suite (VIIRS), and Moderate-Resolution Imaging Spectrometer (MODIS) Aqua) and in situ data is weak, which makes it difficult to assess relationships present between chl-a and toxin concentrations. Moving forward, the development of a regional chl-a algorithm and increased in situ chl-a collection and plankton sampling at a species level will help to improve chl-a measurements and toxic phytoplankton production monitoring around Tasmania.

Incidence of harmful algal blooms in pristine subtropical ocean: a satellite remote sensing approach (Jeju Island)

“…Especially later three year (2015-2017) showed higher annual mean NRTI than prior three years (2012)(2013)(2014). This tendency might be consistent with the case of Tasmania, Australia, which had weak dinoflagellates bloom (Alexandrium catenella) in 2013-2014 and strong ones in 2015-2017 (Trainer et al, 2020;Xie et al, 2021;Wakamatsu et al, 2022). In addition, red tide caused by extreme weather occurred in Chile in 2016 (Armijo et al, 2020;Mardones et al, 2021), and an unusual case (2016 late summer, Figure 7B) occurred on Jeju Island in the same year.…”

Accurate Estimation of Chlorophyll-a Concentration in the Coastal Areas of the Ebro Delta (NW Mediterranean) Using Sentinel-2 and Its Application in the Selection of Areas for Mussel Aquaculture

“…Remote sensing enables the evaluation of the spatial and temporal variability of water quality worldwide, overcoming the lack of data from new, remote, or large marine areas. This has led to several applications of remote sensing in bivalve mollusk aquaculture, including spatial planning [1][2][3][4][5], early detection of harmful algal blooms [6][7][8][9][10][11], and detection of microbial contamination [12,13]. Among the different water quality parameters of interest that can be measured by sensors from satellites, chlorophyll-a concentration is commonly used in bivalve mollusk aquaculture because it is considered the best proxy of phytoplankton biomass [14], which is one of the ecosystem component Essential Ocean Variables (EOVs) [15,16].…”