Brown Bay Research Articles

Características ambientales y algas nocivas en un área de producción de moluscos bivalvos del Canal Beagle, Argentina

En diciembre de 2013 se realizó un estudio para conocer las especies de microalgas tóxicas presentes en el área, las distintas toxinas que producen y los factores ambientales que condicionan la distribución de las comunidades de fitoplancton y su estructura. Se observó una alteración en la estructura de la comunidad fitoplantónica respecto al mismo período de años anteriores que indicó un retraso en las primeras etapas de la sucesión clásica. Dicho retraso influyó en el patrón anual de formación de floraciones de especies tóxicas en el canal y, en consecuencia, en los niveles de toxicidad de los bivalvos que normalmente se registran en esa época. El análisis de HPLC mostró escaso número de toxinas paralizantes de moluscos que coincidió con una muy baja concentración de células tóxicas. En las muestras analizadas se detectaron principalmente gonyautoxinas, sin presencia de toxina amnésica de moluscos. Los resultados aportan un conocimiento más detallado del perfil tóxico de los bivalvos de interés comercial en el área, que complementa el programa de monitoreo en curso. El análisis de los parámetros ambientales mostró que el sector interior de Bahía A. Brown es un área con circulación restringida que puede funcionar como reservorio potencial de los estadios bentónicos de resistencia de algunos dinoflagelados, proveyendo un inóculo inicial para la formación de floraciones o de eventos de toxicidad locales. La ausencia de floraciones de especies tóxicas y el bajo nivel de toxicidad de los moluscos del área en ese período se asociaron con las inusuales condiciones climáticas que se registraron en la región durante los meses previos, lo cual advierte sobre la necesidad de contar con un registro continuo de las variables meteorológicas para tratar de predecir la ocurrencia de floraciones de algas nocivas en el canal.

A sediment mesocosm experiment to determine if the remediation of a shoreline waste disposal site in Antarctica caused further environmental impacts

A shoreline waste disposal site at Casey Station, Antarctica was removed because it was causing impacts in the adjacent marine environment (Brown Bay). We conducted a field experiment to determine whether the excavation created further impacts. Trays of clean, defaunated sediment were deployed at two locations within Brown Bay and two control locations, two years prior to remediation. Trays were sampled one year before, 1month before, 1month after and two years after the excavation. An increase in metals was found at Brown Bay two years after the remediation. However there was little evidence of impacts on sediment assemblages. Communities at each location were different, but differences from before to after the remediation were comparable, indicating there were unlikely to have been further impacts. We demonstrate that abandoned waste disposal sites in hydrologically active places in Antarctica can be removed without creating greater adverse impacts to ecosystems downstream.

Photosynthetic response and recovery of Antarctic marine benthic microalgae exposed to elevated irradiances and temperatures

Exposure to high temperatures affects the photosynthetic processes in marine benthic microalgae by limiting the transport of electrons, thus reducing the ability of the cell to use light. This causes damage to the Photosystem II (PSII) and may lead to photoinhibition. However, the PSII of benthic microalgal communities from Brown Bay, eastern Antarctica, were relatively unaffected by significant changes in temperature. Benthic microalgae exposed to temperatures up to 8°C and an irradiance of 450 μmol photons m−2 s−1 did not experience any photosynthetic damage or irreversible photoinhibition. The effective quantum yield (∆F/Fm′) at 8°C (0.433 ± 0.042) was higher by comparison to cell incubated at −0.1°C (0.373 ± 0.015) with similar irradiances. Temperatures down to −5°C at a similar irradiance showed a decrease in photosynthesis with decreasing temperature, but no severe photoinhibition as the cells were able to dissipate excess energy via non-photochemical quenching and recover from damage. These responses are consistent with those recorded in past studies on Antarctic benthic microalgae and suggest that short-term temperature change (from −5 to 8°C) will not do irreversible damage to the PSII and will not affect the photosynthesis of the benthic microalgae.

Heavy metals monitoring in the southernmost mussel farm of the world (Beagle Channel, Argentina)

Water quality surrounding the mussel farm of Mytilus edulis chilensis at Brown Bay (Beagle Channel) was evaluated. The levels of five heavy metals in sediment and in gill and digestive gland of mussels were examined to consider potential risks to human health. Cd showed the highest enrichment factor in relation to its level in Earth crust (3.85–21.58), which could be related to an upwelling phenomenon. A seasonal trend was found regarding metal bioaccumulation, being higher in winter than in summer. The bioaccumulation pattern in gill was Zn>Fe>Cu>Cd, meanwhile in digestive gland was Fe>Zn>Cu>Cd. Despite Pb was measured in sediment (15.59–23.91μg/gdw), it was not available for being incorporated by mussels. In all cases it was below the detection limit (2.37μg/gdw). With regard to human consumption of mussels from Brown Bay, none of the elements analyzed should cause concern for consumers. Values measured in tissue mussels were below the limit of 10μg/gdw for Cd and Pb established by SENASA for molluscs.Considering that studied mussels are for human consumption and the relatively high levels of metals in sediment may vary their availability if physical parameters changes, periodical monitoring must be carried out to avoid human risks and to produce food in a responsible manner that complies with the food safety standards.

Sediment profile characterisation at contaminated and reference locations in the Windmill Islands, East Antarctica

Sediment profiles for pH, Eh, 28 elements, water and organic content are presented here for human impacted and reference locations in the Windmill Islands, East Antarctica. Variations in element concentrations are observed with increasing depth, especially at Brown Bay where the impact of past human activities is most pronounced in the top 10cm. Spatial differences were observed between sediment profiles at reference and impacted locations and were largely explained by Pb variability in the top 5cm. Median element concentrations from surface, middle and bottom regions of the sediment profile were compared to composite sample medians (no depth stratigraphy) for 11 elements at O’Brien Bay (reference) and Brown Bay (impacted). Pronounced differences were observed for Brown Bay, particularly surface and middle sections, implying that composite samples dilute the near surface anthropogenic signal by mixing with deeper uncontaminated sediment.

Biomarkers and heavy metal bioaccumulation in mussels transplanted to coastal waters of the Beagle Channel

Mussels coming from a mussel farm at Brown Bay (Beagle Channel) were transplanted to four sites inside Ushuaia Bay for 2 and 4 weeks. The objective of this study was to assess the quality of coastal waters of Ushuaia Bay by measuring catalase activity, lipid peroxidation, total lipid content, bioaccumulation of heavy metals and condition index in transplanted mussel Mytilus edulis chilensis. Biomarkers except condition index showed significant differences among exposure times as well as among tissues. Digestive gland presented the highest catalase activity, malondialdehyde level and total lipid content. Digestive gland also was the main target tissue of accumulation of iron and copper, while gill accumulated the highest levels of zinc. A principal component analyzes with the whole set of data allowed to separate stations based on physicochemical conditions and biochemical responses of each studied area.

Lead isotopic signatures in Antarctic marine sediment cores: A comparison between 1 M HCl partial extraction and HF total digestion pre-treatments for discerning anthropogenic inputs

Sensitive analytical techniques are typically required when dealing with samples from Antarctica as even low concentrations of contaminants can have detrimental environmental effects. Magnetic Sector ICP-MS is an ideal technique for environmental assessment as it offers high sensitivity, multi-element capability and the opportunity to determine isotope ratios. Here we consider the Pb isotope record of five marine sediment cores collected from three sites in the Windmill Islands area of East Antarctica: Brown Bay adjacent to the current Australian station Casey, Wilkes near the abandoned US/Australian Station and McGrady Cove lying midway between the two. Two sediment pre-treatment approaches were considered, namely partial extraction with 1 M HCl and total dissolution involving HF. Lead isotope ratio measurements made following sediment partial extraction provided a more sensitive indication of Pb contamination than either Pb concentrations alone (irrespective of sample pre-treatment method) or isotope ratios made after HF digestion, offering greater opportunity for discrimination between impacted and natural/geogenic samples and sites. Over 90% of the easily extractable Pb from sediments near Casey was anthropogenic in origin, consisting of Pb from major Australian deposits. At Wilkes impact from discarded batteries with a unique isotopic signature was found to be a key source of Pb contamination to the marine environment with ~ 70–80% of Pb being anthropogenic in origin. The country and source of origin of these batteries remain unknown. Little evidence was found suggesting contamination at Wilkes by Pb originating from the major US source, Missouri. No definitive assessment could be made regarding Pb impact at McGrady Cove as the collected sediment core was of insufficient depth. Although Pb isotope ratio signatures may indicate anthropogenic input, spatial concentration gradients at nearby Brown Bay suggest contamination at McGrady Cove is unlikely. We recommend Pb isotopic analysis following 1 M HCl partial extraction pre-treatment as a powerful and sensitive method for tracing Pb contamination in marine sediments.

The application of lead isotope ratios in the Antarctic macroalga Iridaea cordata as a contaminant monitoring tool

Lead (Pb) isotope ratios were measured in the marine macroalga Iridaea cordata collected from four locations in the Windmill Islands, East Antarctica. Based on the masses of thalli collected, samples analysed in this study were likely to be a mixture of one and two year old thalli. For a sample of thalli of various ages (<12 months to 2 years old) from the same site there was no apparent variation in Pb concentration or Pb isotope ratio with thallus mass/age, indicating that contaminant sources had been constant over the lifetime of the thalli sampled. I. cordata samples close to the Thala Valley waste disposal site (Brown Bay Inner) near the Australian Station, Casey, displayed isotopic signatures ( 208Pb/ 204Pb 35.99; 206Pb/ 207Pb 1.066; n = 3; average values shown) trending towards that possessed by major Australian Pb sources (Broken Hill and Mt Isa, 208Pb/ 204Pb 35.60; 206Pb/ 207Pb 1.041) suggesting that these samples had been exposed to anthropogenic Pb originating from the Thala Valley waste disposal site. Material collected hundreds of metres from the tip location at Brown Bay Outer had isotopic values ( 208Pb/ 204Pb 36.32; 206Pb/ 207Pb 1.088; n = 10) intermediate between Brown Bay Inner and sites further from the contaminant source at Sparkes Bay and Wilkes ( 208Pb/ 204Pb 36.46; 206Pb/ 207Pb 1.094; n = 4) showing that contaminant transport was predominantly restricted to Brown Bay Inner. This study demonstrates that the isotope ratios of Pb in marine macroalgae can provide valuable information as to the origin and extent of heavy metal flux in a marine environment.

Multiple Pb sources in marine sediments near the Australian Antarctic Station, Casey

An extensive Pb isotope ratio survey of ∼ 100 marine sediment samples from near Casey Station, East Antarctica has been undertaken. Sediment surface grabs and cores were collected over nine years between 1997–2006 and, following HF total digestion, were analysed by magnetic sector ICP-MS. Fifty-two reference samples ([Pb] range 5–26 mg kg − 1 ) from 6 non-impacted locations displayed a broad range of Pb isotope ratios representative of the natural background geology of the region ( 208Pb/ 204Pb ratios of 37.5–40; 206Pb/ 204Pb ratios of 17–19). Potentially impacted sediments from Brown Bay ( n = 27, [Pb] range 18–215 mg kg − 1 ), adjacent to the current and former Australian Stations at Casey (and the associated Thala Valley tip site) showed contamination by Pb characteristic of Broken Hill and Mt Isa Australian deposits ( 208Pb/ 204Pb and 206Pb/ 204Pb values of 35.5–36 and 16.0–16.1, respectively). The nearby abandoned Wilkes Station was previously manned by both US (1957–59) and Australian (1959–69) expeditioners. Adjacent marine sediment samples ( n = 24, [Pb] range 13–40 mg kg − 1 ) displayed Pb isotopic signatures suggesting anthropogenic input from multiple sources. On a three-isotope diagram Wilkes sediments were found to display Pb ratios lying intermediate between Missouri (US), Broken Hill/Mt Isa (Australia)/Idaho (US), and natural geogenic Pb end members. Discarded Pb batteries, paint samples and fuel spills were all considered in this work as possible point sources of Pb contamination to the local environment. Batteries are thought to be the dominant source.

A study of metal and metalloid contaminant availability in Antarctic marine sediments

Previous studies of impacted sites near Casey Station, Antarctica, have revealed elevated concentrations of metals and metalloids, particularly Cd, Cu, Fe, Pb, Sn and Zn in marine sediments. However, attempts to understand the availability and mobility of contaminant elements have not provided a true understanding of speciation. The current work shows, for the first time, that sediments in Brown Bay, an embayment adjacent to the Thala Valley waste disposal site, have elevated concentrations of sulfide, well in excess of that required to bind contaminant metals such as Cd, Cu, Pb and Zn. Furthermore, sediment characterisation using the BCR sequential extraction scheme has shown metal partitioning consistent with sulfides being the controlling factor in metal availability, thus explaining the low porewater concentrations of these metals. The speciation of Sn in Brown Bay, however, is still unclear with the BCR sequential extraction scheme partitioning Sn predominantly into the residual fraction despite Sn being readily extracted by dilute HCl.

Biodegradation of petroleum products in experimental plots in Antarctic marine sediments is location dependent

Clean sediment collected from O’Brien Bay, East Antarctica, was artificially contaminated with a mix of Special Antarctic Blend diesel fuel and lubricating oil and deployed in two uncontaminated locations (O’Brien and Sparkes Bays) and a previously contaminated bay (Brown Bay) to evaluate whether a history of prior contamination would influence the biodegradation process. Detailed analysis of the hydrocarbon composition in the sediment after 11 weeks revealed different patterns of degradation in each bay. Biodegradation indices showed that hydrocarbon biodegradation occurred in all three bays but was most extensive in Brown Bay. This study shows that even within a relatively small geographical area, the longevity of hydrocarbons in Antarctic marine sediments can be variable. Our results are consistent with faster natural attenuation of spilt oil at sites with previous exposure to oil but further work is needed to confirm this. Such information would be useful when evaluating the true risk and longevity of oils spills.

Monitoring the remediation of a near shore waste disposal site in Antarctica using the amphipod Paramoera walkeri and diffusive gradients in thin films (DGTs)

The water quality of a marine embayment (Brown Bay) was monitored during the remediation of an abandoned waste disposal site at Casey Station, East Antarctica, using a combination of biomonitoring and chemical methods. The Antarctic amphipod Paramoera walkeri, in field mesocosms suspended in the water column, was deployed adjacent to the site and at two reference sites for periods of 14 days, repeated three times during the remediation period (December to February). Diffusive gradients in thin film (DGT) samplers were deployed for the same periods to provide estimates of dissolved metals. No difference in mortality of amphipods was observed between Brown Bay and reference sites. There were significant differences, however, in accumulated metal concentrations between amphipods from Brown Bay and reference sites, with greater concentrations of antimony, copper, cadmium, lead, iron and tin at Brown Bay. The melt water/runoff treatment strategy employed for the remediation was successful in preventing acute toxic effects, but water quality was reduced at Brown Bay, where increased metal bioavailability may have been high enough to induce chronic effects in some biota. DGT samplers were less sensitive than amphipods in detecting differences in metal concentrations between sites, indicating that metals bound to suspended particulates were a potentially significant source of contamination.

Evaluation of diffusive gradients in thin film (DGT) samplers for measuring contaminants in the Antarctic marine environment

This work has been the first application of DGT samplers for measuring metals in water and sediment porewater in the Antarctic environment, and whilst DGT water sampling was restricted to quantification of Cd, Fe and Ni, preconcentration using Empore chelating disks provided results for an additional nine elements (Sn, Pb, Al, Cr, Mn, Co, Cu, Zn, As). Although higher concentrations were measured for some metals (Cd, Ni, Pb) using the Empore technique, most likely due to particulate-bound or colloidal species becoming entrapped in the Empore chelating disks, heavy metal concentrations in the impacted Brown Bay were found to be comparable with the non-impacted O’Brien Bay. Sediment porewater sampling using DGT also indicated little difference between Brown Bay and O’Brien Bay for many metals (Cd, Al, Cr, Co, Ni, Cu), however, greater amounts of Pb, Mn, Fe and As were accumulated in DGT probes deployed in Brown Bay compared with O’Brien Bay, and a higher accumulation of Sn was observed in Brown Bay inner than any of the other three sites sampled. Comparison of DGT derived porewater concentrations with actual porewater concentrations showed limited resupply of Cd, Pb, Al, Cr, Mn, Co, Ni, Cu, Zn and As from the solid phase to porewater, with these metals appearing to be strongly bound to the sediment, however, resupply of Fe and Sn was apparent. Based upon our observations here, we suggest that Sn, and to a lesser extent Pb, are critical contaminants.

Constraints on spatial variability in soft-sediment communities affected by contamination from an Antarctic waste disposal site

A small-scale (<500 m length) transect-based survey was conducted in December 1998 to examine the spatial distribution of soft-sediment communities and of concentrations of heavy metals and hydrocarbons in sediments in Brown Bay, adjacent to an abandoned waste dump, at Casey Station, Antarctica. Samples were taken along three transects at increasing distances (nine stations) from the shore-line waste dump. A gradient of contamination was detected, but concentrations of contaminants were very variable with “hotspots” or high levels of contaminants at some stations. Multivariate analysis revealed that the distribution of soft-sediment communities was distinctly different between the inner, middle and outer stations. Abundances of most taxa were very variable with few patterns apparent, but some fauna displayed an abundance gradient from the inner to the outer part of the bay. Many taxa had maximum abundances at outer stations and minimum at inner stations. Multivariate correlations between environmental variables and soft-sediment communities indicated that combinations of some metals (Cd, Cu, Sn, Pb) and grain size (mainly finer fractions, fine sands and coarse silts) were the variables that best “matched” the community patterns within Brown Bay. This study indicated that there were significant correlations between the presence of contaminants and the distribution and composition of soft-sediment communities over very small spatial scales.

EFFECTS OF METAL AND PETROLEUM HYDROCARBON CONTAMINATION ON BENTHIC DIATOM COMMUNITIES NEAR CASEY STATION, ANTARCTICA: AN EXPERIMENTAL APPROACH1

The effects of metals and petroleum hydrocarbons on benthic marine diatom communities were assessed using a manipulative field experiment at Casey Station, Antarctica. Uncontaminated, metal contaminated, and petroleum hydrocarbon contaminated sediments were deployed for 11 weeks during the 1999 austral summer. The treatments were deployed at three different locations: Brown Bay, which has elevated levels of anthropogenic contaminants, and two uncontaminated reference locations, O'Brien Bay and Sparkes Bay, the latter of which has naturally occurring high concentrations of some heavy metals. At each location, significant differences between the composition of diatom communities recruiting to control and petroleum hydrocarbon contaminated treatments were observed. Navicula directa (Smith) Ralfs occurred at lower abundances in the petroleum hydrocarbon contaminated treatments than in the control treatments. In contrast, Navicula cancellata Donkin occurred at higher relative abundances in both contaminated treatments relative to the control treatment. Interactions between treatment and location were also observed for several species, including Navicula glaciei Van Heurck. Significant differences in the overall community composition of diatom communities between control and metal contaminated treatments and metal contaminated and petroleum hydrocarbon contaminated treatments were only observed within Brown Bay. The location of deployment also had a significant influence on the composition of diatom communities. Brown Bay had higher abundances of Achnanthes brevipes Agardh but lower abundances of Navicula aff. cincta (Ehrenberg) Van Heurck than either reference locations. This experiment demonstrated that benthic diatom communities are sensitive to sediment contamination and would be suitable for future monitoring work within this and other areas of Antarctica.

The effects of petroleum hydrocarbon and heavy metal contamination of marine sediments on recruitment of Antarctic soft-sediment assemblages: a field experimental investigation

A manipulative field experiment was conducted at Casey Station, Antarctica, to determine the effect of contamination of marine sediments on the recruitment and development of soft-sediment assemblages. Uncontaminated marine sediments were defaunated and then contaminated by adding hydrocarbons (diesel fuel and lubrication oil) or heavy metals (extracted from contaminated soil) prior to deployment on the seabed for a period of eleven weeks during an Antarctic summer (December to February) at three locations. Two of the locations were intended as reference locations (O'Brien and Sparkes Bay) and were well away from the influence of station activities, but Sparkes Bay was found to be naturally contaminated by some metals. The other location (Brown Bay) was adjacent to an abandoned waste disposal site and is contaminated by hydrocarbons and metals, and soft-sediment assemblages are different from those in control locations. Recruiting assemblages were significantly different between locations and there was a significant effect of sediment contamination. Assemblages in hydrocarbon contaminated sediment were significantly different to those in control and metal treated sediment at two of the locations (Brown and Sparkes Bay). There were no differences between assemblages in control sediment and metal-contaminated sediment. Univariate analyses (ANOVAs) indicated greater abundances of crustaceans, mainly due to several species of gammarid, in control and metal treatments than hydrocarbon-treated sediment. Further analysis ( t-tests) revealed additional differences between hydrocarbon vs. both control and metal treatments, in the total abundance, and abundance of gammarids, tanaids, ostracods, isopods and copepods, particularly at Brown Bay and Sparkes Bay. There was also a trend of greater abundances of polychaetes and gastropods in hydrocarbon and metal treatments compared to the control. In comparison with the hydrocarbon treatment, the metal treatment had little effect. There was significant spatial variability in recruitment within each location, which may have obscured some effects of sediment contamination. There were also significant differences in variability of recruitment between locations. The rate of fauna recruiting to sediments in this experiment at Casey were greater than previously recorded in Antarctica.

Identification and assessment of contaminated sites at Casey Station, Wilkes Land, Antarctica

AbstractIn December 1993 a study of contaminated sites at Casey Station, Wilkes Land, Antarctica, was undertaken. The preliminary assessment of these contaminated sites is presented here. A register of contaminated sites for Casey Station was developed, based on a survey of past Antarctic expeditioners, relevant literature, and in-house reports relating to site usage and history. On this basis a sampling strategy was devised for the highest priority, potentially contaminated sites at Casey Station. Samples were collected from the refuse disposal site (tip site) at Thala Valley and the mechanical workshop/powerhouse areas of ‘Old’ Casey. The results indicated that copper, lead, and zinc were leaching from the tip site into adjacent Brown Bay, with ‘hot spots’ of high petroleum hydrocarbon levels. The mechanical workshop/powerhouse area was also shown to be contaminated with petroleum hydrocarbons, polycyclic aromatic hydrocarbons, and metals such as copper, lead, and zinc. Several recommendations were made, including the removal of rubbish mixed with soil at the bottom end of Thala Valley in such a manner as to prevent any further release of contaminants, with subsequent site monitoring to verify effective removal of contaminants to acceptable environmental levels. It was also recommended that further investigations be carried out on the ecosystem of Brown Bay, the large fuel spill site, the upper and lower fuel-storage areas, and the area around the incinerator. There is scope for monitoring the natural breakdown and migration of contaminants at the mechanical workshop/powerhouse site. This should include studies on bioremediation of hydrocarbon-contaminated soils. Mechanisms for arresting surface migration should be investigated in those sites identified. In addition to meeting some of the international obligations of the Protocol on Environmental Protection to the Antarctic Treaty, this work also contributes towards the development of an approach to assessment and management of contaminated sites that is uniquely adapted to the Antarctic environment and could be applied at other Antarctic stations. to the assessment and management of contaminated sites that is uniquely adapted to the Antarctic environment. This approach could be utilised for site assessments at other Antarctic stations.

Intake Screens for Sampling Fish Populations: The Size-Selectivity Problem

Abstract We compared the size selectivity of the intake screens at the P. H. Robinson generating station on Galveston Bay, Texas with that of a 3-m otter trawl hauled in the intake waters and evaluated a means of predicting size selectivity of the intake screens. We did this for brown shrimp (Penaeus aztecus), white shrimp (Penaeus setiferus), gulf menhaden (Brevoortia patronus), bay anchovy (Anchoa mitchilli), sand seatrout (Cynoscion arenarius), and Atlantic croaker (Micropogonias undulatus). The trawl generally caught smaller individuals than the intake screens, with the relative frequency of catch by size gradually increasing to a peak at an intermediate length of a species, then decreasing as its length increased. Conversely, the relative frequency of collection at the intake screens increased abruptly at a predictable threshold length. Above this threshold, catches decreased gradually, presumably because larger individuals were both less abundant and less susceptible to capture than smaller ones. Ba...

Brown family of Brown's Bay

Brown family of Brown's Bay