Allozyme genotypes and tolerance to copper stress in Hediste diversicolor (Polychaeta: Nereididae)

This study analysed the occurrence of genotypic shifts in laboratory populations of Hediste diversicolor (Polychaeta: Nereididae) exposed to copper stress. Specimens of H. diversicolor were collected at three sites, up to 10 km apart, in the estuarine area of the Pialassa lagoons (North Adriatic Sea, Italy) and were used in acute toxicity tests. Specimens were assigned to copper exposure (0.34 mg/l Cu2+) or control conditions. Each combination of Treatment and Site was replicated in two tanks containing 35 specimens of H. diversicolor. The genotypic structure of both dead and survived specimens was analysed by allozyme electrophoresis at six loci (ALD, FH, HBDH LDH, PGI, SDH). Under copper exposure, specimens with the genotypes ALD100/100 and PGI102/102 had significantly lower mortalities than other genotypes Results were consistent across the three sites, suggesting that, under laboratory conditions, effects of copper stress on H. diversicolor is related to individual genotypes at ALD and PGI loci.     

Influence of bioturbation by Hediste diversicolor on mercury fluxes from estuarine sediments: a mesocosms laboratory experiment

Mercury, with its reactive forms being the most deleterious for the trophic chains, has been identified as a major pollutant in a few confined bodies of the coastal zone. Due to feeding, burrowing, and bioirrigation activities, infauna are known to play a crucial role in the biogeochemical processes of contaminants. The main goal of the present study is to evaluate the effects of Hediste diversicolor bioturbation on mercury fluxes from estuarine sediments in a mesocosms laboratory experiment. Additionally, an attempt was made to establish a relationship between the amount of remobilised mercury to the water column and the degree of contamination of the sediments using a mercury contamination gradient. The present experiment demonstrated that the bioturbation activity caused by the gallery-diffuser H. diversicolor did not influence the remobilisation of mercury (in dissolved reactive forms) from the sediment to the water column. The concentration of dissolved reactive mercury in the water column also did not reflect the degree of contamination in the sediments. The results obtained were in accordance with the sediment characteristics of the Mondego Estuary and Ria de Aveiro (Portugal), since they are very rich in organic matter content, iron/manganese total and hydrous oxides. These physicochemical characteristics of the sediments may partially justify the retention of mercury by these systems, even when they are subjected to bioturbation. In conclusion, sediments with high organic matter content and a high concentration of iron/manganese hydrous oxides allowed for efficient retention of mercury, and the bioturbation process did not seem to affect the system. Another conclusion from this study is that the remobilisation of mercury by bioturbation to the water column is not a fast process, requiring more than 24h. This study constitutes an important work in the area of the effects of bioturbation on mercury remobilisation. Considering the toxicity of mercury for the biota, it is essential to evaluate the real magnitude of mercury processes occurring in estuarine systems in order to obtain essential information on metal behaviour.     

Effects of copper and the sea lice treatment Slice on nutrient release from marine sediments

Copper-based antifoulant paints and the sea lice treatment Slice^® are widely used, and often detectable in the sediments beneath farms where they are administered. Ten-day, whole sediment mesocosm experiments were conducted to examine how increasing sediment concentrations of copper or Slice^® influenced final water column concentrations of ammonium-nitrogen (NH₄-N), nitrate + nitrite-nitrogen (NO_X-N) and phosphate-phosphorus (PO₄-P) in the presence of the non-target, benthic organisms Corophium volutator and Hediste diversicolor. Nominal sediment concentrations of copper and Slice^® had significant effects on the resulting concentrations of almost all nutrients examined. The overall trends in nutrient concentrations at the end of the 10-day incubations were highly similar between the trials with either copper or Slice^®, irrespective of the invertebrate species present. This suggests that nutrient exchange from the experimental sediments was primarily influenced by the direct effect of copper/Slice^® dose on the sediment microbial community, rather than the indirect effect of reduced bioturbation/irrigation due to increased macrofaunal mortality.     

Extent and magnitude of copper contamination in marinas of the San Diego region, California, USA

Marinas are areas of special water quality concern because of the potential for pollutant accumulation within their protected waters. Perhaps the largest contaminant source to marinas is antifouling paints that leach copper to prevent the growth of encrusting organisms on vessel bottoms. Very little monitoring of marinas is typically conducted despite the potential environmental risk, particularly in the San Diego region of California, USA where as many as 17,000 recreational vessels are berthed. The objective of this study was twofold: (1) determine the extent and magnitude of dissolved copper concentrations in marinas throughout the San Diego region, and (2) determine if elevated copper concentrations in marinas of the San Diego region are resulting in adverse biological impacts. A probabilistic study design was used to sample water column copper concentrations and toxicity (using Mytilus galloprovincialis) at 30 stations. Results indicated that exceedence of state water quality objectives was widespread (86% of marina area), but that toxicity was much less prevalent (21% of marina area). Toxicity identification evaluations (TIEs) conducted at the most toxic sites indicated that toxicity was largely due to trace metals, most likely copper. Toxicity was reduced using TIE treatments that chelated trace metals such as cation exchange column, ethylenediaminetetraacetic acid (EDTA), and sodium thiosulfate (STS). Moreover, increasing dissolved copper concentrations correlated with increasing toxicity and these copper concentrations were high enough to account for virtually all of the observed toxicity.     

Cytochrome P4501A biomarker indication of the timeline of chronic exposure of Barrow's goldeneyes to residual Exxon Valdez oil

We examined hepatic EROD activity, as an indicator of CYP1A induction, in Barrow’s goldeneyes captured in areas oiled during the 1989 Exxon Valdez spill and those from nearby unoiled areas. We found that average EROD activity differed between areas during 2005, although the magnitude of the difference was reduced relative to a previous study from 1996/1997, and we found that areas did not differ by 2009. Similarly, we found that the proportion of individuals captured from oiled areas with elevated EROD activity (?2 times unoiled average) declined from 41% in winter 1996/1997 to 10% in 2005 and 15% in 2009. This work adds to a body of literature describing the timelines over which vertebrates were exposed to residual Exxon Valdez oil and indicates that, for Barrow’s goldeneyes in Prince William Sound, exposure persisted for many years with evidence of substantially reduced exposure by 2 decades after the spill.     

Spatial and temporal variability of phytoplankton and environmental factors in a temperate estuary of South America (Atlantic coast,Argentina)

A spatial and temporal study on data collected along the longitudinal gradient of the Principal Channel of Bahía Blanca estuary, Argentina, was carried out during 1992–1993. At nine stations, phytoplankton abundance, chlorophyll a (Chl-a) concentration, inorganic nutrient levels, Secchi disk depth, euphotic depth:mixing depth ratio (Z_eu:Z_m), salinity and temperature were recorded. Phytoplankton abundance, Chl-a concentration and nutrient levels decreased towards the outer zone of the estuary. The inner zone (stations 1 and 2), which was characterized by high turbidity, high nutrient concentrations and high Z_eu:Z_m (>0.16, [critical mixing ratio]), registered the highest phytoplankton abundance and Chl-a concentrations. Temporal variability of data was also noteworthy in this zone. The highest biomass values thus corresponded to June, July, August and the beginning of spring (18 μg Chl-a L⁻¹ and 9×10⁶ cells L⁻¹) concomitantly with a diatom bloom. In the middle zone (stations 3–6), a strong phytoplankton biomass decrease was observed and it coincided with both deep-mixed depths and low Z_eu:Z_m (<0.16). The outer zone (stations 7–9), which was characterized by low phytoplankton biomass values and low nutrient levels all along the year, was the area mostly influenced by waters from the adjacent continental shelf. In view of the above, it can be concluded that the most important primary production in the Bahía Blanca would be produced in the shallow inner zone during winter, being the spatial reach of the phytoplankton biomass principally limited to estuarine waters. Presumably, less than 5% of such biomass may reach the coastal area of the estuary.     

Integrative assessment of organotin contamination in a southern European estuarine system (Ria de Aveiro, NW Portugal): tracking temporal trends in order to evaluate the effectiveness of the EU ban

Organotin (OT) compounds have been used as biocide agents in antifouling paints since the mid 1960s and are now ubiquitous in the marine environment. Due to their high toxicity to non-target species they were banned from antifouling paints in the European Union in 2003 (2002/62/EC directive). The aim of the present work is to assess any obvious decline of the OT environmental levels at Ria de Aveiro (NW Portugal) after the ban. The organotins - monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPT), diphenyltin (DPT), triphenyltin (TPT), monoctyltin (MOT), dioctyltin (DOT) and trioctyltin (TOT) - were quantified in the gastropod Nassarius reticulatus, in the mussel Mytilus galloprovincialis and in sediments. Imposex (imposition of male characters on females of gonochorist gastropods) in N. reticulatus was additionally used as a biomarker of TBT pollution. Time comparisons show a slight decrease of imposex between 2003 and 2005 probably as a consequence of the EU ban, though in some cases this trend seems to have started earlier since 2000. The fraction of TBT relatively to its metabolites has been decreasing over the last years but still remains high suggesting that there are still recent inputs of this compound into the study area.     

Significant variations in the productivity of green macroalgae in a mesotidal estuary: implications to the nutrient loading of the system and the adjacent coastal area

A spatially dynamic model for the productivity of spores and adults of green macroalgae (Enteromorpha sp.) was developed for a mesotidal estuary (Mondego estuary, Portugal). Many of the algal processes and parameters included in the model were experimentally obtained. Model predictions were compared to a real time series (1993-1997) of macroalgal biomass variation and the two sets show a good agreement (ANOVA, P<0.001). Results suggest that algal growth is highly sensitive to small changes in depth and exhibits different patterns of variation in different seasons. On a yearly basis, global calculations for the south channel of the estuary (137 ha) suggest that during bloom years, macroalgal biomass may reach about 21,205 ton DW compared to 240 ton DW in regular years. On a seasonal basis, the difference may be even more significant. The consequences of such variations on the nitrogen and phosphorus loading of the system and the adjacent coastal area are discussed.     

Metallothionein in intestine of red mullet, Mullus barbatus as a biomarker of copper exposure in the coastal marine areas

Dietary metal exposure in fish is studied in native red mullet, Mullus barbatus, involving metallothionein (MT) response in the intestine, a primary site for metal uptake. Intestinal MTs (microg mg(-1) proteins), total proteins (mgml(-1) S50), Cu, Zn, Fe, Mn and Cd (microg ml(-1) S50) are considered as indicators of metal exposure in specimens from near-shore and off-shore locations of the Eastern Adriatic Sea. Metallothionein and Cu are statistically significantly higher in 68 specimens from the Kastela Bay, a near-shore area (30.0+/-6.71microg MT mg(-1) proteins; 0.30+/-0.08microg Cu ml(-1) S50), in comparison to 51 specimens from off-shore area, Solta Island (25.9+/-4.21microg MT mg(-1) proteins; 0.26+/-0.09microg Cu ml(-1) S50). Cytosolic Cu, a MT inducer, is significantly correlated (p<0.05, r=0.44) with MT in specimens from the Kastela Bay, independent on fish biometry. Our study indicates that cytosolic intestinal Cu and MT represent a measurable biochemical response in red mullet specimens, dwelling above sediments contaminated with Cu.     

Changes of P, Ca, Al and Fe contents in fringe marshes along a pedogenic chronosequence in the Pearl River estuary, South China

Soil and plant samples were collected in four fringe marsh zones (i.e., A, B, C and D zones) along a pedogenic chronosequence in the Pearl River estuary in the Spring of 2009. Samples were subjected to a total digestion technique and analyzed for P, Ca, Al and Fe in order to study the changes of nutrient contents, storages in soils and their bioavailabilities to wetland plants (e.g. Cyperus malaccensis) in four zones. Results showed that soil Ca increased with depth along soil profiles, while P, Al and Fe generally kept constant in soil profiles in four zones. Al and Fe contents in the top 10 cm soils showed significant decreases from D to A zone, while a significant increase in Ca contents (P<0.05). Significant increases along pedogenic chronosequence for P, Al and Fe at 30-40 cm soil horizons were also observed. Ca was mainly accumulated in plant aboveground parts; Al and Fe were accumulated in the belowground parts; while P was homogenously distributed among the tissues of C. malaccensis. C. malaccensis in D zone had lower Bio-concentration factors (BCFs) of P in the shoots and Al and Fe in the roots, and higher values of Ca in the shoots than those in older zones (P<0.05). Compared to Al and Fe, both Ca and P had relatively higher translocation capacities for C. malaccensis, while only lower TFs for P and higher values for Al and Fe in D zone were observed than those in A and B zones (P<0.05). Except for Al with no significant changes, the total BCFs for P and Fe showed an increasing trend with soil ages, while a decreasing trend for Ca. The total bio-storage factors (TBSFs) of P and Ca declined with the pedogenic time, whereas an increase for Fe. The results of this study can contribute to the wetland conservation and management in the Pearl River estuarine region.     

A survey of imposex in muricids from 1996 to 2000 and identification of optimal indicators of tributyltin contamination along the east coast of Phuket Island,Thailand

The present investigation is the most extensive survey of imposex in gastropods from the west coast of Thailand. Imposex in Thais distinguenda increased significantly (p < 0.001; Chi Square test for trend) from 1996 to 2000 at 21 stations in Phangna Bay, Thailand. Females with imposex increased, extending from 3.5 km in 1996 to 10 km from the harbour areas in 1999 and 2000. Increasing intensity of imposex was also observed for Thais bitubercularis from 1996 to 2000. The less sensitive species: Morula musiva, Morula granulata, Morula margariticola and Thais rufotincta only developed imposex at the three main areas of intense shipping activities. T. bitubercularis and T. distinguenda are recommended as indicators of tributyltin (TBT) in Southeast Asia because of their sensitivity and wide distribution in the region. The results suggest that TBT contamination is worsening, against global trends, because regulations prohibiting the use of TBT-based paints, do not exist in Thailand.     

Multixenobiotic resistance, acetyl-choline esterase activity and total oxyradical scavenging capacity of the Arctic spider crab, Hyasaraneus, following exposure to bisphenol A, tetra bromo diphenyl ether and diallyl phthalate

The Arctic has become a sink for persistent organic pollutants (POPs) originating from lower latitudes, and relatively high levels have been found in different biota. Recent studies have identified detrimental effects on wildlife including endocrine disruption, impairment of enzyme activity, and reduced immune function. The Arctic spider crab, Hyas araneus, shown interesting potential for its use as sentinel organism in polar ecosystems. This study investigated the effect of 2,2',4,4'-tetra bromo diphenyl ether (BPDE), bisphenol A (BPA), and diallyl phthalte (DPA) on H. araneus in a three weeks exposure study. Expression of multixenibiotic resistance (MXR) proteins has been studied using the C219 monoclonal antibody which allows identifying an immunoreactive protein of 40 kDa in the digestive gland while no such protein could be observed in the gills. Expression of this protein was increased by exposure to DPA (+75%; p<0.05, n=10). All compounds significantly affected muscle acetylcholine esterase (AChE) activity (p<0.05, n=10) with 50 microg/L DPA having the strongest effect by lowering the value to 37% of control. The total oxyradical scavenging capacity measured in the digestive gland toward peroxyl, hydroxyl and peroxynitrite was also significantly reduced indicating a decreased resistance to oxidative stress generated by DPA (p<0.05, n=5). These results thus suggest the potential detrimental effects of DPA even at concentration as low as 50 microg/L on H. araneus.     

Auklet (Charadriiformes: Alcidae, Aethia spp.) chick meals from the Aleutian Islands, Alaska, have a very low incidence of plastic marine debris

The ingestion of plastic marine debris is a chronic problem for some of the world’s seabird species, contributing to reduced chick survival, population declines, and deposition of contaminants via absorption in birds’ gastrointestinal tract. We analysed the frequency of ingested plastic in chick meals delivered by adults in four species of auklet - Crested (Aethia cristatella), Least (A. pusilla), Parakeet (A. psittacula), and Whiskered (A. pygmaea) - from three breeding colonies in the Aleutian Islands, Alaska, USA over a 14-year period from 1993 to 2006. Among 2541 chick meals, we found plastic in only one - from a Whiskered Auklet on Buldir Island in 1993. While adult Parakeet Auklets have a high frequency of plastic ingestion (over 90%), no chick meals contained plastic. Unlike other seabirds, the planktivorous auklets do not appear to offload plastic to their chicks, and we conclude that auklet chicks are probably at a low risk of contamination from plastic debris.     

Recovery from imposex by a population of the dogwhelk, Nucella lapillus (Gastropoda: Caenogastropoda), on the southeastern coast of England since May 2004: A 52-month study

Over a 52-month period beginning in May 2004 and concluding in August 2008, and coinciding with the period over which TBT was banned as a ship anti-foulant globally, a population of the dogwhelk, Nucella lapillus, was studied for changes in population size and structure, and reproduction. During the study period, the size of the population of N. lapillus on the Mewsbrook Groyne at Littlehampton on the southeastern coast of England grew from ∼25 individuals to >500, i.e., a 20-fold increase. Similarly, population structure normalised to reveal a maximum age of up to ∼3 years. The numbers of egg capsules produced by the N. lapillus population also grew over the study, again by a factor of 20, and the length of the breeding season increased from 7 months in 2004-2005 and 2005-2006 to 11 months in 2006-2007 and 2007-2008. Such changes were reflected in the incidence of imposex from Vas Deferens Index Stages 3 and 4 in 2003 to zero commencing in 2008 and continuing into 2009.Due to a lack of confirmatory chemical data, the changes in population size, structure and reproduction herein reported upon for N. lapillus cannot be correlated positively with changes in ambient TBT levels, but they can and are correlated with freedom from imposex. This is the first time such a dramatic recovery from imposex, following the banning of TBT, has been documented.