A compilation of existing literature on the characteristics of Southern Ocean diatom species.

Collection of processed BGC-Argo float profiles, used to calculate phytoplankton phenology from chlorophyll, phytoplankton carbon and nitrate.

The effect of ocean alkalinity enhancement on a coastal phytoplankton community was assessed via a microcosm experiment. The effect of alkalinity enhancement in two scenarios (i) when enclosed seawater was in equilibrium with atmospheric CO2 and (ii) when enclosed seawater was not in equilibrium with atmospheric CO2 were explored. Alkalinity was increased by ~497 umol/kg in these two treatments and plankton communities, carbonate chemistry, dissolved inorganic nutrients, particulate matter and chlorophyll a dynamics monitored over a 22 day period where a spring bloom occurred.

These files contain the data recorded from a mesocosm experiment conducted in Bergen, Norway 2022 which assessed the effect of simualted mineral-based (silicate or calcium) ocean alkalinity enhancement (OAE) on diatom silicification. Ten mesocosms were used in total, divided into two groups either the silicate- or calcium based group and alkalinity was increased by either 0, 150, 300, 450 or 600 µmol L-1 above natrually occuring levels. The PDMPO-fluorescence (an appropriate proxy for silicification) of diatoms was recorded on eight seperate days during the experiment. Accompanying data includes measured; macronutrients (nitrate, nitrite, phophate, silicate), total alkalinity, biogenic silica in the water column and sediment trap.

Phytoplankton productivity in the polar Southern Ocean (SO) plays an important role in the transfer of carbon from the atmosphere to the ocean’s interior, a process called the biological carbon pump, which helps regulate global climate. SO productivity in turn is limited by low iron, light, and temperature, which restrict the ef- ficiency of the carbon pump. Iron and light can colimit productivity due to the high iron content of the photosynthetic photosystems and the need for increased photosystems for low-light acclimation in many phytoplankton. Here we show that SO phytoplankton have evolved critical adaptations to enhance photosynthetic rates under the joint constraints of low iron, light, and temperature. Under growth-limiting iron and light levels, three SO species had up to sixfold higher photosynthetic rates per photosystem II and similar or higher rates per mol of photosynthetic iron than tem- perate species, despite their lower growth temperature (3 vs. 18 °C) and light intensity (30 vs. 40 μmol quanta·m2·s−1), which should have decreased photosynthetic rates. These unexpectedly high rates in the SO species are partly explained by their unusually large photosynthetic antennae, which are among the largest ever recorded in marine phytoplankton. Large antennae are disadvan- tageous at low light intensities because they increase excitation energy loss as heat, but this loss may be mitigated by the low SO temperatures. Such adaptations point to higher SO production rates than environmental conditions should otherwise permit, with implications for regional ecology and biogeochemistry.

Comprehensive baseline environmental data for Storm Bay in south eastern Tasmania were required to inform the salmonid industry regarding site selection, to provide background environmental data before large-scale farming commences, and to support the development of a scientifically relevant and cost-effective environmental monitoring program. Storm Bay is a large deep bay that receives freshwater inflow from the River Derwent on its north-western boundary and exchanges water with Frederick Henry Bay on its north-eastern boundary. The eastern and western boundaries are defined by the Tasman Peninsula and Bruny Island, respectively, and the southern boundary connects with the Tasman Sea. This area is a mixing zone between the River Derwent outflow and oceanic waters. The oceanography in Storm Bay is complex and is characterized by considerable fluctuations in temperature, salinity and nutrients on variable temporal and spatial scales. This is due to the southerly extension of warm nutrient-depleted sub-tropical waters transported via the East Australian Current (EAC) down the east coast of Tasmania over summer, whilst the south and south-west coasts are influenced by cooler, nutrient-rich sub-Antarctic waters from the south and the Leeuwin Current from the north-west (Buchanan et al. 2014). The current project arose in response to the salmon aquaculture industry recognising the need for increased scientific knowledge to support ecologically sustainable development of Atlantic salmon (Salmo salar) farming operations in south-eastern Tasmania, particularly expansion into Storm Bay. The information provided will assist salmon companies to manage their operations in Storm Bay under varying environmental conditions. Our research has also provided the opportunity to investigate changes in water quality over a quarter of a century, as CSIRO investigated seasonal and inter-annual variability in chemical and biological parameters in Storm Bay during 1985-89. We sampled at the same “master station” in Storm Bay as CSIRO and used similar procedures where possible. Five sites were sampled monthly in Storm Bay for over five years from November 2009 to April 2015, except on rare occasions when weather conditions were unsuitable, and bimonthly at times in 2013 when external funding was not available. Site 1 was located at the mouth of the Derwent estuary and the entrance to Storm Bay, site 2 was in the same location as the ‘master site’ of a CSIRO study in 1985-88, site 3 was furthest offshore and provided the most information on oceanic currents influencing the bay, while sites 5 and 6 were requested by the salmon aquaculture industry as potential sites for expansion of salmon farming. Site 4 was further offshore and monitoring at this site was discontinued after three months because of insufficient time to collect samples from all sites in one day. An additional site, 9, at the entrance to Frederick Henry Bay was included from 18 July 2011 at the request of the Marine Farming Branch, Department of Primary Industries, Parks, Water and Environment (DPIPWE), to provide information on water quality coming from Frederick Henry Bay. Adjacent to, and largely unaffected by the River Derwent, Frederick Henry Bay is a large marine embayment with limited freshwater input from the Coal River at its northern boundary. ---------------------------------------------- See child records linked to this parent record for specific context and methodologies for each of the monitoring variables (phytoplankton, zooplankton, chlorophyll, pigment, nutrients, oceanography).