Water temperature, averaged across the water column, in Storm Bay followed a distinct seasonal cycle each year, reaching a low of 9 °C and a high of ~ 19 °C. Warmest temperatures were in February, followed by a gradual cooling throughout autumn to a winter minimum in August, then increasing again during spring. Across the sites, the median temperature varied little, with site 3, the most marine of the sites, showing the least spread in values. Median salinity varied little across Storm Bay, being slightly higher at sites 3 and 6, highlighting the marine nature of site 3 and the patterns of seawater circulation in Storm Bay. The lowest salinities were recorded at site 1, where less saline surface waters flow into the bay from the Derwent Estuary. Seasonally, salinity was highest in autumn, with slightly fresher water present in Storm Bay in spring. Some lower salinity values were recorded in July and August, suggesting the presence of less saline subantarctic water flowing into the bay, or freshwater flow from the Derwent. Glider transects show slight lower salinity in summer, then mild stratification in autumn to spring, especially in the shallow regions near the mouth of the Derwent.

Chlorophyll a concentration is widely used as a proxy to describe trends in phytoplankton biomass over spatial and temporal scales. The concentration of chlorophyll a in Storm Bay showed surprisingly little variation across the seasons. There was a gradient in concentration from site 1 to site 3, where chlorophyll a decreased slightly. It was highest and most variable at the inshore sites 1 and 9, and lowest at site 3, furthest out in the bay. There was no clear annually recurrent seasonal bloom, although data suggests higher values in spring and autumn (see later time series).

Phytoplankton was counted and identified from five sites over the 5-year period. Annual cycles in abundance are available (as cells mL-1), along with detailed species identification. Cell measurements and approximate geometric shape were also recorded for the calculation of biovolume (μL cell-1). Diatoms and dinoflagellates dominated the samples in terms of biomass, however, small cells were also very abundant throughout each year. The data are restricted to an integrated sample from the top 12 m of the water column. Fluorescence profiles elsewhere in this dataset can provide an indication of phytoplankton presence lower in the water column.

This data describes the characterisation and estimated concentration of marine plastics in waters around Australia from surface net tows. The marine plastics recorded were predominantly small fragments (‘‘microplastics’’) resulting from the breakdown of larger objects made of polyethylene and polypropylene (e.g. packaging and fishing items). This data accompanies the following publication: Reisser J, Shaw J, Wilcox C, Hardesty BD, Proietti M, et al. (2013) Marine Plastic Pollution in Waters around Australia: Characteristics, Concentrations, and Pathways. PLoS ONE 8(11): e80466. doi:10.1371/journal.pone.0080466

Biologically relevant macronutrients, nitrate + nitrite, silicate, phosphate and ammonia, were measured at all sites throughout the study. Nitrate + nitrite values (NOx) at the surface showed clear seasonal trends, peaking over winter and drawing down to near zero in summer and autumn. Phosphate concentrations also reached a peak in winter, which was associated with Southern Ocean influence. Median ammonium concentrations at all sites were generally <0.5 μM, with no clear peaks in any season or month. Overall, the lowest values were measured in August and other months showed reasonable spread around the median. Median silicate concentrations were consistently highest at sites 1 and 9, followed by site 5. Water from the River Derwent flows through site 1, then tracks east towards site 9 then site 5. Seasonally, silicate was generally highest in winter when the River Derwent outflow is also greatest.