[1] Reports of hypoxic conditions (oxygen <1.5 ml L −1 ) off the U.S. west coast over the last two decades led us to investigate hypoxia in the Southern California Bight (SCB) and its potential impacts on fisheries. The secular trend in hypoxia in the SCB over the last 57 years is not monotonic, and reversed trend in the mid-1980s, bringing oxygen concentrations back to levels measured in the late 1950s to early 1960s. Thirty-seven percent of the rockfish (Sebastes spp.) habitat in the Cowcod Conservation Area at 240-350 m depths suffers exposure to hypoxia in the summer of normal years. If current trends in shoaling of low oxygen water continue for another 20 years, rather than reversing as happened previously, we predict loss of 18% of the habitat with 55% of the total habitat exposed to hypoxia.

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Shelf waters of southern Australia support the world's only northern boundary current ecosystem. Although there are some indications of intense nitrate enrichment in the eastern Great Australian Bight (GAB) arising from upwelling of the Flinders Current, the biological consequences of these processes are poorly understood. We show that productivity in the eastern GAB is low during winter, but that coastal upwelling at several locations during the austral summer-autumn results in localized increases in surface chlorophyll a concentrations and downstream enhancement of zooplankton biomass. Sardine (Sardinops sagax) and anchovy (Engraulis australis) eggs and larvae are abundant and widely distributed in shelf waters of the eastern and central GAB during summer-autumn, with high densities of sardine eggs and larvae occurring in areas with high zooplankton biomass. Egg densities and distributions support previous evidence suggesting that the spawning biomass of sardine in the waters off South Australia is an order of magnitude higher than elsewhere in southern Australia. Sardine comprised >50% of the identified prey species of juvenile southern bluefin tuna (SBT, Thunnus maccoyii) collected during this study. Other studies have shown that the lipid content of sardine from the GAB is relatively high during summer and autumn. We suggest that juvenile SBT migrate into the eastern and central GAB during each summer-autumn to access the high densities of lipid-rich sardines that are available in the region during the upwelling period. Levels of primary, secondary and fish production in the eastern GAB during summer-autumn are higher than those recorded in other parts of Australia, and within the lower portion of ranges observed during upwelling events in the productive eastern boundary current systems off California, Peru and southern Africa.

California sea lions increased from approximately 50 000 to 340 000 animals in the last 40 years, and their pups are starving and stranding on beaches in southern California, raising questions about the adequacy of their food supply. We investigated whether the declining sea lion pup weight at San Miguel rookery was associated with changes in abundance and quality of sardine, anchovy, rockfish and market squid forage. In the last decade off central California, where breeding female sea lions from San Miguel rookery feed, sardine and anchovy greatly decreased in biomass, whereas market squid and rockfish abundance increased. Pup weights fell as forage food quality declined associated with changes in the relative abundances of forage species. A model explained 67% of the variance in pup weights using forage from central and southern California and 81% of the variance in pup weights using forage from the female sea lion foraging range. A shift from high to poor quality forage for breeding females results in food limitation of the pups, ultimately flooding animal rescue centres with starving sea lion pups. Our study is unusual in using a long-term, fishery-independent dataset to directly address an important consequence of forage decline on the productivity of a large marine predator. Whether forage declines are environmentally driven, are due to a combination of environmental drivers and fishing removals, or are due to density-dependent interactions between forage and sea lions is uncertain. However, declining forage abundance and quality was coherent over a large area (32.5–38° N) for a decade, suggesting that trends in forage are environmentally driven.

A study of climatological and conductivity‐temperature‐depth (CTD) data for 2004 is made to provide a conceptual model of upwelling for the eastern region of the Great Australian Bight. In particular, the data and other studies provide strong evidence that shelf break upwelling is confined to the southwest Kangaroo Island region and does not occur farther to the west off the Eyre Peninsula. Rather, the upwelled water is likely to remain in a Kangaroo Island “pool” until subsequent upwelling events draw the water to the shallower and surface coastal regions of the eastern Bight. In this manner the surface upwelling apparent off the Bonney Coast, Kangaroo Island, and the eastern Great Australian Bight (GAB) can appear to be simultaneous. Moreover, it appears likely that the water within the Kangaroo Island pool remains nutrient rich. Support for this model comes from CTD sections collected in 2004 that show that the upwelled signal (cool, <17°C; fresher, <35.6; dense, σt > 26 kg m−3) diminishes in width and intensity with increasing distance from Kangaroo Island. The pattern of fluorescence is similar to that for temperature in the upwelled plume and indicates that the Kangaroo Island pool remains nutrient rich. Relatively low oxygen concentrations may indicate a previous bloom. The warmest water is found near the shelf break along with very low values of fluorescence and relatively higher levels of oxygen suggesting nutrient‐limited growth of phytoplankton. These data also support the notion that the upwelled nutrient‐rich water is supplied from the Kangaroo Island pool and not by shelf break upwelling in the eastern GAB. Anomalously salty and fresh water is identified as resulting from evaporation in coastal bays and groundwater aquifer discharge.

The OceanGliders program started in 2016 to support active coordination and enhancement of global glider activity. OceanGliders contributes to the international efforts of the Global Ocean Observation System (GOOS) for Climate, Ocean Health, and Operational Services. It brings together marine scientists and engineers operating gliders around the world: (1) to observe the long-term physical, biogeochemical, and biological ocean processes and phenomena that are relevant for societal applications; and, (2) to contribute to the GOOS through real-time and delayed mode data dissemination. The OceanGliders program is distributed across national and regional observing systems and significantly contributes to integrated, multi-scale and multi-platform sampling strategies. OceanGliders shares best practices, requirements, and scientific knowledge needed for glider operations, data collection and analysis. It also monitors global glider activity and supports the dissemination of glider data through regional and global databases, in realtime and delayed modes, facilitating data access to the wider community. OceanGliders currently supports national, regional and global initiatives to maintain and expand the capabilities and application of gliders to meet key global challenges such as improved measurement of ocean boundary currents, water transformation and storm forecast.

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