The use of transplanted cultured mussels (Mytilus edulis) to monitor pollutants along the Ninety Mile Beach, Victoria, Australia— II. Polychlorinated dibenzo-p-dioxins and dibenzofurans

Commercially cultured strings of mussels were transplanted to five sites along the Ninety Mile Beach, Victoria, Australia, to assess the operational impact of an ocean outfall on bioaccumulation of dioxins and furans. The monitored outfall discharges a complex effluent containing secondary treated domestic, industrial and pulp and paper mill effluent as well as oil and gas production waste waters. Mussels were deployed twice yearly for a period of 3 years, with both pre-discharge and post-discharge data collected. Mussel tissue furan concentrations were generally below detection limits, whereas dioxins were detected in all tissue samples. Tissue dioxin congener profiles were similar to unpolluted seawater, with penta-, hepta- and octa-substituted dioxin congeners being detected in the highest concentrations. Tissue concentrations of dioxins and furans in deployed mussels provided no evidence to suggest that bioaccumulation of dioxins discharged from the ocean outfall was occurring.     

Assessment of the effects of a marine urban outfall discharge on caged mussels using chemical and biomarker analysis

To assess the presence of endocrine disruptors in treated marine outfall discharges and their possible effects, mussels (Mytilus galloprovincialis) were caged in the environmental mixing zone of the outfall of the Santander sanitation system and in one control area. After 30, 60 and 90 days, samples were collected to perform chemical analyses (metals, anionic surfactants, alkylphenols, bisphenol A, phthalates and estrogenic hormones), biomarkers of general stress (lysosomal membrane stability-LMS, histopathology) and biomarkers of endocrine disruption (vitellogenin-like proteins and gonad index). There were no significant differences between outfall and control sites on contaminant levels, except for 4-tert-octylphenol which was higher in the outfall site. Bacteriological counts were higher in the outfall area. No relevant differences in biomarkers were detected between treated and control mussels. A significant reduction in LMS occurred in both groups after 90 days caging, indicating a stress situation possibly related to caging or to post-spawning reproductive state.     

Stable carbon and nitrogen isotope signatures indicate recovery of marine biota from sewage pollution at Moa Point,New Zealand

Stable carbon and nitrogen isotopes have been used to assess sewage contamination of a sewage outfall, discharging milli-screened effluent into Moa Point Bay, New Zealand, and monitor the recovery of flora and fauna after the outfall's closure. An initial study characterising the extent of the discharge and the effects on seaweed (Ulva lactuca L.), blue mussels (Mytilus galloprovincialis) and limpets (Cellana denticulata) from the area, showed effects of the sewage discharge on flora and fauna were localised within in the bay. The immediate area surrounding the discharge area was found to contain limited biodiversity, with an abundance of Ulva lactuca, a bright green lettuce-like seaweed, typically found in areas with high nutrient input, limpets and small blue mussels. The nitrogen isotopic signature (delta15N) is shown to be a good tracer of sewage pollution in seaweed and associated grazers (i.e. limpets) as a result of the increased contribution of urea and ammonia to seawater nitrogen derived from the effluent. The carbon isotopic signature (delta13C) is suggested as a more appropriate sewage tracer for mussels, which filter feed the effluent's particulate organic matter from the water. Lower carbon:nitrogen ratios were found in Ulva lactuca sampled from around the outfall region compared to uncontaminated control sites. However carbon:nitrogen ratios do not vary significantly amongst shellfish species.After closure, monitoring continued for 9 months and showed that the carbon and nitrogen isotopic signatures of algae (Ulva lactuca L.) returned to similar control site levels within 3 months. Limpet and blue mussels (Cellana denticulata and Mytilus galloprovincialis) showed slower recovery times than the Ulva lactuca, with detectable levels of the sewage-derived carbon and nitrogen remaining in the animal's tissue for up to 9 months.     

Sublethal effects of a chlorinated and heated effluent on the physiology of the mussel,Mytilus edulis L.: A reduction in fitness for survival?

Coastal power stations entrain large volumes of cooling water, requiring biocidal treatment to prevent biological fouling. Discharged effluent is both heated and contaminated with residual traces of biocide and so it is necessary to quantify the impacts of this discharge. Cooling water from Heysham 2 nuclear power station, NW England, UK, is discharged to the intertidal area, via a culvert (to minimise erosion and maximise dilution and dispersion by directing the effluent into the receiving water at all states of the tide) within which the effluent is contained at low water. The culvert and surrounding coastal area support a population of blue mussels (Mytilus edulis). Mussel health was determined along a gradient of exposure, using three physiological indices: Scope for Growth, Gonad Mantle Index and Somatic Condition Index (K Factor). The Mussels within the culvert exhibited reduced physiological index values compared to an external site. A trend was identified down the length of the culvert, representing a gradient of exposure and indicating a potential negative effect on growth and reproductive output.     

Mortality,growth and fecundity of transplanted mussel and barnacle populations near a pulp mill outfall

The mortality, growth and fecundity of transplanted adult mussel (Mytilus edulis) and barnacle (Balanus glandula) populations near a kraft pulp mill outfall at Port Mellon, British Columbia, were determined. The results indicated that adults of both species were tolerant of bleached kraft pulp mill effluent and survived near the pulp mill outfall. However, the growth rates of both species were retarded when compared with those at the control station. The reproductive activities of the transplanted barnacles were also impaired.     

Improvement of the sediment ecosystem following diversion of an intertidal sewage outfall at the Fraser river estuary,Canada, with emphasis on Corophium salmonis (Amphipoda)

Primary treated sewage effluent from the city of Vancouver, Canada was deposited directly onto the intertidal ecosystem of Sturgeon bank, Fraser river estuary between 1962 and 1988. In response to the degraded sediment conditions an azoic zone developed near the discharge outfall. Effluent discharges into the intertidal zone were almost completely stopped in 1988 with the construction of a submerged outfall. Our studies, conducted between 1994 and 1996, showed considerable improvement in the environment of the mudflat ecosystem, including increased dissolved oxygen, decreased sediment chlorophyll, decreased organic material in the sediment, reduced heavy metals in surficial sediment and increased grain size. The amphipod Corophium salmonis, important in the food web for juvenile salmon and other fish species, recolonized the previously azoic location. At reference stations, C. salmonis density was similar to that observed in previous surveys two decades earlier. Our data strongly suggest that improvement or sediment conditions near the former sewage outfall was a major factor enabling colonization by C. salmonis.     

An offshore biomonitoring system for chlorinated hydrocarbons

Uncontaminated intertidal mussels transferred to a tautline buoy system near a major submarine outfall off southern California proved to be useful bio-indicators of water column contamination. Mussel survival exceeded 90%, and specimens maintained for 13 weeks near the polluted bottom (35 m) and the sea surface accumulated DDT above control concentrations by factors of 200 and 20, respectively. Corresponding factors for PCB were 60 and 6.     

Use of physiological responses in Mytilus trossulus as integrative bioindicators of sewage pollution

Mussels, Mytilus trossulus (average shell length 43+/-0.8 mm), were sampled from a beach in Alaska that received untreated sewage for several years, a second beach adjacent to a secondary wastewater outfall, and two nearby reference beaches. Survival time in air, byssal thread production rate, and prevalence of trematode parasites were determined for each group. Tolerances to aerial exposure was significantly lower (P<0.05) at both sewage outfall sites than at the reference sites. Mussels exposed to untreated sewage produced fewer byssal threads and had a significantly higher prevalence of encysted trematodes than mussels from the other beaches, including the secondary wastewater site. Survival in air, byssal thread production, and trematode prevalence in mussels may be useful indicators in evaluating the longterm health of beaches exposed to sewage.     

The effect of the new Massachusetts Bay sewage outfall on the concentrations of metals and bacterial spores in nearby bottom and suspended sediments

Since the new outfall for Boston's treated sewage effluent began operation on September 6, 2000, no change has been observed in concentrations of silver or Clostridium perfringens spores (an ecologically benign tracer of sewage), in bottom sediments at a site 2.5 km west of the outfall. In suspended sediment samples collected with a time-series sediment trap located 1.3 km south of the outfall, silver and C. perfringens spores increased by 38% and 103%, respectively, in post-outfall samples while chromium, copper, and zinc showed no change. All metal concentrations in sediments are <50% of warning levels established by the Massachusetts Water Resources Authority. An 11-year data set of bottom sediment characteristics collected three times per year prior to outfall startup provides perspective for the interpretation of post-outfall data. A greater than twofold increase in concentrations of sewage tracers (silver and C. perfringens) was observed in muddy sediments following the exceptional storm of December 11-16, 1992 that presumably moved contaminated inshore sediment offshore.     

Are toxic contaminants accumulating in Massachusetts coastal sediments following startup of the Massachusetts Bay outfall: a comprehensive comparison of baseline and post-diversion periods

The Massachusetts Water Resources Authority (MWRA) conducts monitoring to address concerns related to the 2000 diversion of secondarily treated effluent discharge into Massachusetts Bay. Baseline data (1992-2000) showed multiple regions defined by physical and chemical composition. Near the Massachusetts Bay outfall, there is a series of heterogeneous sediments in relatively close proximity to the primary historic source of contaminants (Boston Harbor). Farfield sediments exhibited greater compositional definition from one another, which was attributed to the greater spatial separation of the sampling locations. Factors that influence contaminant variability include local and distributed sources, and are primarily related to gradients in depositional environments. Post-diversion sediment data suggest that 4 years of treated effluent discharge has not increased contaminant concentrations to the bay system. However, abundance of the sewage tracer, Clostridium perfringens, has increased variably in sediments located within 2 km of the outfall, providing a distinct effluent signal near the outfall.     

Mercury pollution in the waters around Harboøre Tange and Limfjord,Denmark

High concentrations of mercury have been measured in mussels (Mytilus edulis) collected in two ‘hot spot’ areas: (1) near a closed-down chemical factory on the west coast of the Limfjord, and (2) on groynes in the immediate vicinity of a chemical deposit in the dunes on the Danish west coast. By collecting comparable samples of mussels from chains of buoys, the mercury pollution in the western Limfjord could be traced 50–100 km into the central and innermost parts of the Limfjord as a gradual decreasing mercury concentration gradient. By collecting mussels from groynes north and south of the chemical deposit, it was possible to monitor the relative extent of the mercury leakage to the North Sea before and after the excavation of the deposit. The investigations have demonstrated the applicability of M. edulis as a monitoring organism for mercury when importance is attached to concentration gradients and distribution patterns in well defined and homogeneous samples of mussels collected from natural populations.     

Measuring bioavailable metals using diffusive gradients in thin films (DGT) and transplanted seaweed (Fucus vesiculosus), blue mussels (Mytilus edulis) and sea snails (Littorina saxatilis) suspended from monitoring buoys near a former lead–zinc mine in West Greenland

Measuring loads of bioavailable metals is important for environmental assessment near mines and other industrial sources. In this study, a setup of monitoring buoys was tested to assess loads of bioavailable metals near a former Pb–Zn mine in West Greenland using transplanted seaweed, mussels and sea snails. In addition, passive DGT samplers were installed. After a 9-day deployment period, concentrations of especially Pb, Zn and Fe in the species were all markedly elevated at the monitoring sites closest to the mine. Lead concentrations in all three species and the DGT-Pb results showed a significant linear correlation. Zinc and Fe concentrations were less correlated indicating that the mechanisms for Zn and Fe accumulation in the three species are more complex. The results show that there is still a significant load of metals from the mine and that such buoys can be an adequate method to assess present loads of bioavailable metals.     

A new sentinel organism for vanadium and titanium

Using X-ray Energy Spectroscopy trace metal concentrations (Ti, V, Mn, Fe, Ni, Cu, Zn, As, Pb) were measured in specimens of Eudistylia vancouveri (feather duster tube worms) collected from floating wharves near and far from a storm water outfall in a metropolitan area. As for the well-studied bio-accumulator Mytilus edulis (mussels), higher metal concentrations were noted in specimens near the pollution source. In particular the worms accumulated certain metals, namely vanadium and titanium, not picked up by the mussels, signaling that a new sentinel organism could be available.     

Tracing the influence of sewage discharge on coastal bays of Southern Vancouver Island (BC,Canada) using sedimentary records of phytoplankton

The impact of sewage and stormwater effluents on phytoplankton is investigated by comparing organic-walled dinoflagellate cyst abundance and diversity from 38 surface sediment samples, flanking southern Vancouver Island. Site locations include those directly adjacent to wastewater outfall at Clover and Macaulay Points and Saanich Peninsula, as well as from a variety of near-shore environments with differing tidal flow influences. Excellently preserved dinoflagellate cyst assemblages have been recovered and 36 cyst taxa were identified. Local assemblages are characterized by a high relative proportion (average 56%) of cysts produced by heterotrophic dinoflagellates, which is typical for regions of high primary production. Relative proportional increases of cysts from heterotrophic species with particular increases of Polykrikos kofoidii/schwartzii and Dubridinium species, known to reflect areas affected by eutrophication, occur directly adjacent to all three sewage outfalls, as well as in the more stagnant waters of Esquimalt and Victoria Harbours and at the mouth of Cadboro Bay. Further effects of an anthropogenic effluent can be seen in the relatively higher concentrations of organic carbon and the diatom production proxy, biogenic opal. Results from this study clearly indicate a much larger impact zone than predicted by a sewage effluent plume model or trends found in monitored benthic biota and sediment chemistry that evidence primary outfall affects <800 m eastward of Macaulay Point and about 200 m eastward of the Clover Point. Enhanced production of cysts from potentially toxic Alexandrium species is also observed near locations of sewage outfalls.     

Cross-shelf transport into nearshore waters due to shoaling internal tides in San Pedro Bay, CA

In the summer of 2001, a coastal ocean measurement program in the southeastern portion of San Pedro Bay, CA, was designed and carried out. One aim of the program was to determine the strength and effectiveness of local cross-shelf transport processes. A particular objective was to assess the ability of semidiurnal internal tidal currents to move suspended material a net distance across the shelf. Hence, a dense array of moorings was deployed across the shelf to monitor the transport patterns associated with fluctuations in currents, temperature and salinity. An associated hydrographic program periodically monitored synoptic changes in the spatial patterns of temperature, salinity, nutrients and bacteria. This set of measurements show that a series of energetic internal tides can, but do not always, transport subthermocline water, dissolved and suspended material from the middle of the shelf into the surfzone. Effective cross-shelf transport occurs only when (1) internal tides at the shelf break are strong and (2) subtidal currents flow strongly downcoast. The subtidal downcoast flow causes isotherms to tilt upward toward the coast, which allows energetic, nonlinear internal tidal currents to carry subthermocline waters into the surfzone. During these events, which may last for several days, the transported water remains in the surfzone until the internal tidal current pulses and/or the downcoast subtidal currents disappear. This nonlinear internal tide cross-shelf transport process was capable of carrying water and the associated suspended or dissolved material from the mid-shelf into the surfzone, but there were no observation of transport from the shelf break into the surfzone. Dissolved nutrients and suspended particulates (such as phytoplankton) transported from the mid-shelf into the nearshore region by nonlinear internal tides may contribute to nearshore algal blooms, including harmful algal blooms that occur off local beaches.     

Minor improvement for intertidal seaweeds and invertebrates after acid mine drainage diversion at Britannia Beach, Pacific Canada

In December 2001, acid mine drainage (AMD) from an abandoned copper mine at Britannia Beach (British Columbia, Canada) was diverted to flow from Britannia Creek into an outfall at 30 m depth in Howe Sound. Britannia Beach was studied in early 2003 to determine whether AMD diversion resulted in improved conditions for intertidal organisms. Species number and abundance have increased at the intertidal zone since AMD diversion, although they were still lower than at an unpolluted control site nearby (Furry Creek). Survivorship and growth rates of transplanted Mytilus trossulus (mussel) have increased since AMD diversion, although they were still significantly lower than at the control site. Transplanted Fucus gardneri (seaweed) performed better than before the AMD diversion; at Britannia Beach the chlorophyll a concentration in tissues was not significantly different from that at the control site, although the concentration of chlorophyll c in tissues and the chlorophyll c to a ratio was lower than at the control site six weeks after transplantation. Britannia Beach is still subject to leaching of metals from surrounding soils, low levels of AMD coming down the creek, and AMD discharge from the deep outfall. Although there has been an improvement, the intertidal environment at Britannia Beach still seems unable to support normal growth and survival of organisms.     

The effects of wastewater effluent and river discharge on benthic heterotrophic production,organic biomass and respiration in marine coastal sediments

We examine effects of high river particulate flux and municipal wastewater effluent on heterotrophic organic carbon cycling in coastal subtidal sediments. Heterotrophic production was a predictable (r² = 0.95) proportion (56%) of oxidized OC flux and strongly correlated with organic/inorganic flux. Consistent growth efficiencies (36%) occurred at all stations. Organic biomass was correlated with total, OC and buried OC fluxes, but not oxidized OC flux. Near the river, production was modest and biomass high, resulting in low P/B. Outfall deposition resulted in depleted biomass and high bacterial production, resulting in the highest P/B. These patterns explain why this region is production “saturated”. The δ¹⁵N in outfall effluent, sediments and dominant taxa provided insight into where, and which types of organisms feed directly on fresh outfall particulates, on older, refractory material buried in sediments, or utilize chemosynthetic symbiotic bacteria. Results are discussed in the context of declining bottom oxygen conditions along the coast.     

Comparative petroleum hydrocarbons levels and biochemical responses in mussels from hydrothermal vents (Bathymodiolus azoricus) and coastal environments (Mytilus galloprovincialis)

Aliphatic hydrocarbons and PAHs in the whole soft tissues of Bathymodiolus azoricus from three Mid-Atlantic Ridge hydrothermal vents (Menez-Gwen, Lucky Strike and Rainbow), and Mytilus galloprovincialis from three contaminated coastal sites in South Portugal were analysed, and its effects on the digestive gland microsomes mixed-function oxygenase system (MFO) were assessed. Aliphatic hydrocarbons levels were present in the same magnitude in both coastal and hydrothermal environments, while the UCM (unresolved complex mixture) for coastal mussels were higher than in vent mussels. In general, significantly higher PAHs concentrations were found in coastal mussels, compared to B. azoricus where low molecular weight PAHs (2-3 rings) represented the majority of PAHs contrarily to what was observed in M. galloprovincialis. The MFO components were present in both mussel species, and were detected in vent mussels for the first time. However this system seems to have different roles in species from these contrasting environments. In coastal mussels MFO responded to hydrocarbon contamination while response in hydrothermal organisms appeared to be related mainly to endogenous factors.     

Effects of the North Head deep-water sewage outfall on nearshore coastal reef macrobenthic assemblages

The macrobenthos on the coastal reefs near the North Head deep-water outfall were sampled nine times over a 3 year period to determine whether patterns in diversity and abundance were affected by the outfall. The assemblages were sampled using an asymmetrical after control/impact design (ACI). Ten replicate quadrats at each of three sites nested within each of three locations were photographed using a jump camera. These photographs were sampled to provide estimates of the number and abundance of major taxa and abundances of individual species. Significant interactions between outfall vs control through time were detected for the total number of species, bryozoans, cnidarians and the abundances of a silt matrix and two species of bryozoans. Smaller scale interactions among sites through time occurred for the abundances of total fauna, sponges and an ascidian species representing some evidence for the effect of the outfall at these smaller spatial scales. This paper summarizes the correlative evidence of effects from the outfall.     

Numerical responses of larval fishes to deepwater sewage disposal: a field assessment

This paper summarizes the results of a large-scale ‘beyond BACI’ designed assessment of the influences of effluent discharges from Sydney's deepwater sewage outfalls on assemblages of larval fishes. Larval fishes were sampled at three outfalls and at multiple control locations three times before and three times after the deepwater outfalls were commissioned. Sampling was stratified to account for time of year, oceanography and plume behaviour. Large numbers of fish larvae were caught near the outfalls and were thus exposed to sewage plumes. Results indicated that some larvae that normally occur at depth were displaced upwards by rising plumes, particularly when plumes surfaced. No predictable positive or negative numerical responses of larvae to outfalls were evident. Rather responses varied depending on the taxa, outfall and season. The large inherent level of natural spatial and temporal variability in abundances of larvae swamped the detection of possible impacts for many taxa. Future field based studies need to track larvae through plumes to assess changes in numbers, but also to test effects on the health and condition of larvae.