Glass sponges are enigmatic members of the deep-sea fauna that inhabit shallow waters in only a few locations world-wide. In order to understand what factors influence the distribution of glass sponges, patterns of distribution and abundance of reef and non-reef forming hexactinellids in fjords of British Columbia, Canada, were analyzed from photographs and transcripts recorded on dives undertaken by the 'Pisces IV' manned submersible during the 1980s. Hexactinellids are widely distributed throughout all fjords from 16 to 650 m depths, and in some fjords abundances reach 240 individuals in 10 m 2 . In all fjords hexactinellids were most abundant at depths of 20 to 260 m, even where water depths exceeded 500 m. Glass sponges were rare in regions of inlets where oxygen levels fall below 2 ml l -1 , or in areas of high sediment deposition. Highest abundances coincided with water conditions of high dissolved silicate, low light, temperatures between 9 and 10°C and low suspended sediments. Extensive glass sponge skeletons in the inner basin of Howe Sound reflect past stress in this fjord that may include oxygen deficit, sediment loading from a mine and contamination from industrial sites. The observations from 'Pisces IV' suggest that glass sponges may be sentinel species for current and past seawater conditions in coastal British Columbia.

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Discharge of sewage to the environment in the form of treated or untreated wastewater can have serious impacts on human health and quality of life and on ecosystem condition. Since a previous review in 1997, upgrades to wastewater treatment facilities, along with improved source control, have produced successes in reducing loadings of certain pollutants (e.g., mercury, polychlorinated biphenyls) to Canadian waters. However, nationally, loads of phosphorus discharged from wastewater treatment facilities have not changed in recent years (2003–2008), and releases of nitrogen have increased slightly. In some locations, wastewater discharges are contributors to bacterial contamination, toxicity from heavy metals and ammonia, and eutrophication, all of which continue to threaten public and environmental health. An increasing number of studies are also demonstrating developmental, reproductive, and behavioural changes in fish and other aquatic organisms from exposure to pharmaceuticals, personal-care products, or other pollutants in domestic wastewater, even after treatment. Minimizing wastewater discharge and mitigating its effects on the environment and human health will be a challenge. It is critical that gains achieved by improved wastewater treatment and other control measures not be reversed by relaxation of efforts or by failure to keep pace with population growth.

During the North Atlantic spring bloom, a seasonal phytoplankton community succession takes place from diatoms to non-siliceous phytoplankton. Diatoms rely on silica to form their frustules and are out-competed by other species when silica becomes depleted. Diatoms are also expected to contribute significantly to export production in the North Atlantic. We suggest that a lower boundary to export production can be estimated as the component of total production that occurs between the start of the spring bloom and the time when silica becomes depleted. This method has been tested in the Irminger Basin, located between Greenland and Iceland, in the North Atlantic. A technique to estimate silica concentration from satellite-derived sea surface temperature and chlorophyll a concentration has been developed and used to determine silica concentration at high spatial and temporal resolution. This facilitates an estimation of the timing of silica depletion and thus the timing of the transition from a phytoplankton community dominated by diatoms to dominance by non-siliceous species. The timing of the initiation of the bloom, defined as a pronounced and sustained increase in biomass, is estimated from a Sea-viewing Wide Field-of-View Sensor (SeaWiFS)-derived chlorophyll a concentration. A lower-boundary estimate of export production is made and, additionally, estimates of the contribution to export production by diatoms and non-diatoms are made by considering silica-to-nitrate drawdown ratios. We estimate export production in this region to be ~60 g C m -2 yr -1 , of which diatoms account for ~65%.

The majority of the Southern Ocean is a high-nutrient low-chlorophyll (HNLC) ecosystem. Localized increases in chlorophyll concentration measured in the wake of bathymetric features near South Georgia demonstrate variations in the factors governing the HNLC condition. We explore the possibility that the contrast between these areas of high-chlorophyll and surrounding HNLC areas is associated with variations in phytoplankton photophysiology. Total dissolvable iron concentrations, phytoplankton photophysiology and community structure were investigated in late April 2003 on a transect along the North Scotia Ridge (53–54°S) between the Falkland Islands and South Georgia (58–33°W). Total dissolvable iron concentrations suggested a benthic source of iron near South Georgia. Bulk community measurements of dark-adapted photochemical quantum efficiency (F v/F m) exhibited a sharp increase to the east of 46°W coincident with a decrease in the functional absorption cross-section (sPSII). Phytoplankton populations east of 46°W thus displayed no physiological symptoms of iron or nitrate stress. Contrasting low F v/F m west of 46°W could not be explained by variations in the macronutrients nitrate and silicic acid and may be the result of taxon specific variability in photophysiology or iron stress. We hypothesize that increased F v/F m resulted from local relief from iron-stress near South Georgia, east of Aurora Bank, an area previously speculated to be a “pulse point” source of iron. Our measurements provide one of the first direct physiological confirmations that iron stress is alleviated in phytoplankton populations near South Georgia