Transgenerational plasticity in the sea: context-dependent maternal effects across the life history

Maternal effects can have dramatic influences on the phenotype of offspring. Maternal effects can act as a conduit by which the maternal environment negatively affects offspring fitness, but they can also buffer offspring from environmental change by altering the phenotype of offspring according to local environmental conditions and as such, are a form of transgenerational plasticity. The benefits of maternal effects can be highly context dependent, increasing performance in one life-history stage but reducing it in another. While maternal effects are increasingly well understood in terrestrial systems, studies in the marine environment are typically restricted to a single, early life-history stage. Here, I examine the role of maternal effects across the life history of the bryozoan Bugula neritina. I exposed maternal colonies to a common pollution stress (copper) in the laboratory and then placed them in the field for one week to brood offspring. I then examined the resistance of offspring to copper from toxicant-exposed and toxicant-na?ve mothers and found that offspring from toxicant-exposed mothers were larger, more dispersive, and more resistant to copper stress than offspring from na?ve mothers. However, maternal exposure history had pervasive, negative effects on the post-metamorphic performance (particularly survival) of offspring: offspring from toxicant-exposed mothers had poorer performance after six weeks in the field, especially when facing high levels of intraspecific competition. Maternal experience can have complex effects on offspring phenotype, enhancing performance in one life-history stage while decreasing performance in another. The context-dependent costs and benefits associated with maternally derived pollution resistance may account for why such resistance is induced rather than continually expressed: mothers must balance the benefits of producing pollution-resistant larvae with the costs of producing poorer performing adults (in the absence of pollution).     

Differential tolerance to metals among populations of the introduced bryozoan Bugula neritina

Resistance to heavy metals is a potentially important trait for introduced marine organisms, facilitating their successful invasion into disturbed natural communities. We conducted laboratory and field experiments to examine differential resistance to copper (Cu) between two source populations of the introduced bryozoan Bugula neritina, originating from a polluted (Port Kembla Harbour, NSW, Australia) and an unpolluted (Botany Bay, NSW, Australia) environment. A laboratory toxicity test was conducted to test the relative resistance of B. neritina recruits from the two sources, by measuring the attachment success, survival and growth of individuals exposed to a range of Cu concentrations (0, 25, 50 and 100 μg l⁻¹ Cu). Upon completion, reciprocal transplantation of the colonies to the original polluted and unpolluted locations was carried out to assess ongoing survival and growth of colonies in the field. B. neritina colonies originating from the polluted Port Kembla Harbour had increased resistance to Cu relative to populations from an unpolluted part of Botany Bay. There appeared to be a cost associated with increased metal tolerance. In the laboratory, Botany Bay recruits displayed significantly higher growth in control treatments and significantly poorer growth at 100 μg l⁻¹ Cu with respect to Port Kembla Harbour individuals, which showed unusually uniform and low growth irrespective of Cu concentration. No difference in attachment success or post-metamorphic survival was observed between populations. Field transplantation showed copper resistance in Port Kembla Harbour colonies constituted an advantage in polluted but not benign environments. The findings of this study provide evidence of the benefits to invasive species of pollution tolerance and suggest that human disturbance can facilitate the establishment and spread of invasive species in marine systems.     

The common mussel Mytilus edulis as an indicator of pollution by zinc,cadmium, lead and copper. I. Effects of environmental variables on uptake of metals

The net uptake of zinc, cadmium, lead and copper by the common mussel Mytilus edulis (L.) exposed to different conditions was investigated with a view to using this species as an indicator of contamination of the marine environment by these metals. The variables studied were season, position of the mussel in the water column, water salinity, water temperature, and the simultaneous presence of all four metals. Each of these 5 variables affected the net uptake of some or all of the metals studied under some conditions. Seasonal variation in concentrations of zinc, cadmium and copper was found in samples collected at three separate locations. The relationship of seasonal variation to tissue weight and absorption route of the metals is discussed. Near to freshwater inputs of trace metals, the concentrations of zinc, cadmium and lead in mussels were found to vary according to the depth at which the mussels were collected; in summer when freshwater run-off is less, this effect was absent. Low salinities did not affect the net uptake of zinc by mussels, but increased the net uptake of cadmium and decreased that of lead. Low temperatures had no effect on the net uptake of zinc or lead; the net uptake of cadmium was unaffected by low temperatures at high salinities but was decreased by low temperatures at low salinities. The presence of the other metals had no effect on the individual net uptake of either zinc, cadmium or lead. A sampling programme was devised to eliminate the effects of these environmental variables and to allow the use of M. edulis as an indicator of zinc, cadmium and lead in marine and estuarine environments. In contrast to the other metals, the net uptake of copper by the mussel was extremely erratic, and was affected by salinity and temperature changes and by the presence of the other metals and changes in their relative concentrations. The effects of other metals on the net uptake of copper cannot be easily eliminated or allowed for; it is, therefore, suggested that the mussel should not be used as an indicator of copper in the marine environment.     

Wide-spread genetic variability and the paradox of effective population size in the gag,Mycteroperca microlepis,along the West Florida Shelf

Wide-ranging marine species are often described as having a low effective population size (N _e) to census size (N) ratio. This genetic phenomenon is typically attributed to large variation among individuals in reproductive success because of the high mortality rates and unpredictable environments associated with larval dispersal. In this study, we examined patterns of genetic variation in gag (Mycteroperca microlepis) on the West Florida Shelf across year classes of post-settlement juveniles and spawning adults. With no significant genetic differentiation among year classes despite varying recruitment dynamics, little evidence for chaotic genetic patchiness, and no truncation of adult genetic diversity in subsequent juvenile cohorts, there was little support for large variation among individual in reproductive success contributing to a low N _e/N ratio. In fact, the consistent lack of significant differences in annual recruitment classes indicated that reproductive success among individuals was resistant to skewing. Among the various evolutionary forces that may be affecting N _e, changes to demography due to fishing pressure are posited as a likely mechanism affecting current levels of genetic variation.     

铜、锌对3种常见乔木抗氧化指标的复合影响

为了解不同浓度铜（Cu）、锌（Zn）重金属污染土壤对乔木抗氧化指标的影响以及为植物修复蠡河重金属污染岸带提供理论依据,选取广玉兰（Magnoliagrandiflora）、香樟（Cinnamomumcamphora）、榉树（Zelkovaschneideriana）幼苗,采用土培法浇灌重金属溶液模拟土壤污染环境,研究不同浓度重金属Cu／Zn对乔木脯氨酸含量、过氧化物酶活性、过氧化氢酶活性及丙二醛含量的单一及复合影响。实验表明,单一Cu胁迫对广玉兰、香樟和榉树的毒害作用较单一,Zn胁迫严重;Cu／Zn复合作用下,3种乔木抗氧化指标均在Cu15和Zn110时达到最大值,表现出较强的抗性,而后随着复合作用强度增加,重金属对其毒害作用增大;75μg／gCu和210μg／gZn单一及复合胁迫时,广玉兰丙二醛含量相对香樟和榉树较接近对照值,过氧化物酶和过氧化氢酶活性较大,脯氨酸含量差别不大。综合分析,不同乔木在不同浓度重金属胁迫下抗氧化指标作出不同响应,广玉兰对高浓度Cu／Zn胁迫不敏感,承受能力和抗性较强,适合于修复Cu／Zn污染较严重土壤。     

Determining the drivers of population structure in a highly urbanized landscape to inform conservation planning

Understanding the environmental contributors to population structure is of paramount importance for conservation in urbanized environments. We used spatially explicit models to determine genetic population structure under current and future environmental conditions across a highly fragmented, human‐dominated environment in Southern California to assess the effects of natural ecological variation and urbanization. We focused on 7 common species with diverse habitat requirements, home‐range sizes, and dispersal abilities. We quantified the relative roles of potential barriers, including natural environmental characteristics and an anthropogenic barrier created by a major highway, in shaping genetic variation. The ability to predict genetic variation in our models differed among species: 11–81% of intraspecific genetic variation was explained by environmental variables. Although an anthropogenically induced barrier (a major highway) severely restricted gene flow and movement at broad scales for some species, genetic variation seemed to be primarily driven by natural environmental heterogeneity at a local level. Our results show how assessing environmentally associated variation for multiple species under current and future climate conditions can help identify priority regions for maximizing population persistence under environmental change in urbanized regions.     

Metal contamination increases the sensitivity of larvae but not gametes to ocean acidification in the polychaete Pomatoceros lamarckii (Quatrefages)

Ocean acidification is not happening in isolation but against a background of chronic low-level pollution for most coastal marine environments. The reproductive and larval stages of marine invertebrates can be highly sensitive to the impacts of both environmental pollutants and ocean acidification, but very little is currently known regarding the potential impacts of combined contaminant and high CO₂ exposures on the health of marine organisms. Ocean acidification research to date has focused heavily on the responses of calcifying marine invertebrate larvae and algae, and as such the polychaetes as a group, despite their ecological importance, remain understudied. Here, we investigate the effects of elevated seawater CO₂ (pH range 8.1–7.4, plus an extreme pH of 7.2 in the sperm motility experiments), in combination with the environmental pollutant copper (0.002 μM), on the early life history stages of the intertidal polychaete Pomatoceros lamarckii from two populations. P. lamarckii sperm appear to be robust to elevated seawater CO₂. Whilst all three of the sperm motility end points measured showed a response to elevated CO₂, these responses were small and not linear. The percentage of motile sperm and sperm curvilinear velocity were significantly reduced in the lower pH treatments of 7.4 and 7.2, whereas sperm straight-line velocity (VSL) was mostly unaffected except for an increased VSL at pH 8.0. Fertilisation success was investigated using two populations from the South West (UK), one from Torquay and one from Plymouth Sound. Fertilisation success was slightly but significantly reduced at the 7.6 and 7.4 pH treatments for both populations (a 9.0 % reduction in fertilisation success from pH 8.1 to 7.4 for Torquay), but with a greater effect observed in the population from Plymouth Sound (a 13.33 % reduction in fertilisation success). No additional impact of 0.002 μM copper exposure on fertilisation success was found. Larval survival was found to be much more sensitive to elevated CO₂ than sperm function or fertilisation, and a significant interaction with copper exposure was observed. These results demonstrate the potential for polychaete larvae to be affected by predicted ocean acidification conditions and that chronic coastal pollutants, such as copper, have the potential to alter larval susceptibility to ocean acidification conditions.     

Response of benthic foraminifera to heavy metal contamination in marine sediments (Sicilian coasts,Mediterranean Sea)

To examine the suitability of benthic foraminifera and their test deformations as bioindicators of pollution in coastal marine environments, we studied foraminifera and metal concentrations in 72 marine sediment samples, collected from the inner shelf along the Sicilian coast (Gulfs of Palermo and Termini) and on the south-eastern coast of Lampedusa Island. These areas are characterised by different environmental conditions. On the basis of pollution sources and foraminiferal assemblages, we recognised different zones in the Gulf of Palermo. The most polluted zones showed high metal concentrations, and low diversity of benthic foraminifera with species typical of stressed environments. By contrast, the lowest polluted zones showed a high population density and the highest percentages of epiphytes. Epiphytes were abundant where a Posidonia oceanica meadow was present and decreased in the most polluted zones. Sediments of the Gulf of Termini and Lampedusa exhibited high percentages of benthic foraminifera typical of well-oxygenated waters and low concentrations of metals, with the exception of sites located near sewage outfalls and harbour areas. Furthermore, even though deformed tests are commonly known in natural stressed environmental conditions, this study shows that in the most polluted zones, benthic foraminifera were characterised by the highest percentages of deformed individuals.     

Contrasting population structures in two sympatric fishes in the Baltic Sea basin

Detailed multispecies studies on the patterns of genetic variability and differentiation in marine environments are still rare. Using mitochondrial and nuclear genetic markers, we compared genetic variability and population structuring of threespine (Gasterosteus aculeatus) and ninespine (Pungitius pungitius) sticklebacks from the same eleven marine and six freshwater locations within the Baltic Sea basin. Analyses of both marker types revealed a significantly lower degree of genetic structuring in both marine and freshwater populations of threespine than those ninespine sticklebacks. Isolation-by-distance (IBD) was detected across the marine populations in both species, suggesting spatially limited gene flow. However, the levels of genetic diversity and differentiation across the localities were uncorrelated between the two species in both marine and freshwater environments. Accordingly, estimates of effective population sizes were larger and migration rates were higher for three- than for ninespine sticklebacks. Hence, ninespine stickleback populations from the Baltic Sea basin appear to be subject to stronger genetic drift than sympatric threespine sticklebacks, and the proximate reason for this difference is likely to be found from autecological differences between the two species. In accordance with the earlier studies, genetic variability was higher and the degree of genetic differentiation was lower in marine than in freshwater populations in both species.     

Hydrology influences population genetic structure and connectivity of the intertidal amphipod Corophium volutator in the northwest Atlantic

The mechanisms driving genetic structure in marine systems are elusive due to the difficulty of identifying temporal and spatial barriers to dispersal. By studying marine invertebrate species with limited dispersal potential, genetic structure can be directly related to physical and biological factors restricting connectivity. In the northwest Atlantic, the benthic brood-rearing amphipod Corophium volutator is distributed across basins with distinct circulation patterns and has the potential to disperse passively during its adult stage. We analyzed spatial genetic variation and migration rates across C. volutator’s North American range with sequence data for mitochondrial DNA and three novel nuclear markers using frequency and coalescent-based methods. We found low genetic differentiation within basins, but strong subdivision within the Bay of Fundy and a striking biogeographic break between the Bay of Fundy and Gulf of Maine, suggesting that genetic drift may act on populations in which connectivity is restricted due to the limitation of passive dispersal by hydrological patterns.     

Differences in kelp morphology between wave sheltered and exposed localities: morphologically plastic or fixed traits?

The ability of algae to change the shape of their thallus in response to the environment may be of functional and ecological importance to the alga, with many species of macroalgae exhibiting a great range of morphological variation across wave exposure gradients. However, differences in morphology detected between sheltered and exposed environments cannot determine whether such differences represent plastic responses to the local environment or whether morphology is genetically fixed. This study tested for differences in the morphology of the common kelp, Ecklonia radiata, between wave sheltered and exposed environments, and reciprocally transplanted juveniles to distinguish the nature of such differences (i.e. plastic vs fixed traits). Differences between exposure environments were consistent with known effects of exposure (i.e. a wide, thin thallus at sheltered sites and a narrow, thick thallus with a thick stipe at exposed sites). The reciprocal transplant experiment confirmed that morphological plasticity was the mechanism enabling this alga to display different patterns in morphology between exposure environments. Individuals transplanted to the exposed environment underwent a rapid and extreme response in morphology, which was not apparent in individuals transplanted to the sheltered environment that responded more slowly. These results suggest that stressors typical of sheltered environments (i.e. diffusion stress) may not be as influential (if at all) compared to stressors typical of exposed environments (i.e. breakage, dislodgement) in differentiating morphological characters between exposure environments.     

海洋溢油污染的生态与健康危害

随着溢油事故的频繁发生,海洋溢油污染备受关注.本文在阐述国内外海洋溢油污染现状的基础上,针对溢油污染对人类健康的影响进行了初步分析,并针对海洋环境中溢油的环境行为以及对海洋生态系统、沿岸滩涂生态系统的毒性效应进行了概述.最后,对海洋溢油污染研究的发展趋势进行了展望.     

环境中抗药基因水平转移研究进展

抗药基因是一种新型环境污染物,一旦被致病菌获得,将导致抗生素的临床使用失效,从而危害公共健康。抗药基因可通过转移因子在细菌间传播,加剧抗药基因的扩散效应,提升了环境健康风险性,因此抗药基因水平转移受到了越来越多的关注。本文介绍了抗药基因水平转移的分子机制,总结了不同环境中各种抗药基因水平转移途径的研究现状,并对该领域将来的研究方向提出了展望,以期为环境中抗药基因的调查评估、污染控制及合理管理提供理论参考。     

Facilitation across stress gradients: the importance of local adaptation

While there is some information on genetic variation in response to competition in plants, we know nothing about intraspecific variation in facilitation. Previous studies suggest that facilitation should increase fitness in stressful environments. However, whether a plant experiences an environment as stressful may depend on prior adaptive responses to stressors at a site. Local adaptation to stress at a site may reduce the likelihood of facilitation. Seeds of Plantago erecta from stressful (serpentine soil) and non-stressful (non-serpentine soil) edaphic environments were reciprocally planted into these two soil types. Although competition did not differ significantly among seed sources, there was evidence for a local adaptation effect on facilitation. Non-serpentine seeds planted into serpentine soil exhibited greater individual plant biomass at higher densities. The interaction between population source and growth environment indicates a role for evolutionary processes such as local adaptation in the expression of facilitation in plants.     

Copper tolerance in a population of Silene vulgaris ssp. maritima (A. & D. Love) at Dolfrwynog Bog near Dolgellau,North Wales

Clones of Silene vulgaris ssp. maritima individuals from Dolfrwynog Bog, North Wales and from a coastal control site were propagated under standardised environmental conditions. After five months, cuttings were taken and tested for copper tolerance by means of root extension analysis in solutions of various different copper concentrations. Indices of tolerance suggested that individuals from the Dolfrwynog population were more resistant to elevated copper concentrations than were the control population individuals. Due to the initial five months under standardised conditions, it was assumed that the cloned plant material would have lost all plastic adaptive responses to its native environment. If this assumption was valid then the differences in copper tolerance observed between the two populations had a genetic basis and the Dolfrwynog Bog population is a copper tolerant ecotype.     

Biological benthic tools as indicators of coastal marine ecosystems health

Coastal marine ecosystems are increasingly subjected to environmental stress and degradation due to pollution. Several research programmes have addressed this problem and produced relevant data sets for specific areas, often including consistent sets of environmental and biological variables. The value of existing information gathered from these types of data can be largely increased by combining them into a common data set to determine globally applicable relationships. To perform this exercise, the Intergovernmental Oceanographic Commission (IOC) of UNESCO has recently formed the Ad hoc Study Group on Benthic Indicators (http://www.ioc.unesco.org/benthicindicators) with the aim of developing robust indicators of benthic health. In this paper, initial products and ongoing activities of this international initiative are described and discussed. An expansion of initial IOC/UNESCO research on benthic fauna-organic carbon relationships is also presented. As part of this follow-up research, the relationship between total organic carbon concentrations of sediment and abundance, biomass and species diversity of benthic macrofauna was evaluated using data sets from 2 different regions of the world comprising 3 different coastal marine environments. The ability of identifying threshold levels in selected variables that could serve as indicators of related adverse environmental conditions leading to stress in the benthos is envisaged within the frame of a larger joint analysis, carried out by the IOC/UNESCO Study Group on Benthic Indicators, of merged data sets from several coastal regions worldwide.     

SO_2和NO_2胁迫对红花荷等植物光合生理影响及抗性评价

为探讨红花荷（Rhodoleia championii）等12种园林植物抗SO2和NO2污染能力,以1～2年生实生苗为材料,通过人工气候室的盆栽实验,研究不同SO2和NO2混合气体胁迫对园林植物苗木光合参数和相对叶绿素含量的影响,并利用隶属函数法及系统聚类分析法对其抗SO2和NO2污染能力进行了综合评价。结果表明,植物叶片净光合速率、气孔导度、蒸腾速率和相对叶绿素含量基本上随着SO2和NO2胁迫的加剧而逐渐降低,但水分利用效率受净光合速率和蒸腾速率变化的影响规律不明显。综合隶属函数和聚类分析可知,红花荷和红千层（Callistemon rigidus）抗污染能力强,杜鹃红山茶（Camellia azalea）和粉红羊蹄甲（Bauhinia blakeana）抗污染能力较强,红花银桦（Grevillea robusta）和无忧树（Saraca divespierre）抗污染能力中等,大叶紫薇（Lagerstroemia speciosa）、金花风铃木（Tabebuia chrysantha）和腊肠树（Cassia fistula）抗污染能力较弱,而本地火焰木（Spathodea nilotica）、复羽叶栾树（Koelreuteria bipinnata）和樱花（Prunus serrulata）抗污染能力弱。研究结果为火电厂、陶瓷厂、钢铁厂、石化厂等重度酸污染地区植物选择提供参考。     

A critical review of the emerging research on the detection and assessment of microplastics pollution in the coastal,marine, and urban Bangladesh

● Coastal and marine regions are the most studied for microplastic pollution. ● Tourism is a major cause of microplastic pollution in coastal regions. ● Sediments contain larger microplastics while fish ingest smaller microplastics. ● Inland lakes, rivers, and freshwater fish are impacted by microplastic pollution. ● Microplastics are found in edible salts, however, presence is less in refined salt. The research on the extent and effects of microplastics pollution in the Global South is only getting started. Bangladesh is a South Asian country with one of the fastest growing economies in the world, however, such exponential economic growth has also increased the pollution threats to its natural and urban environment. In this paper, we reviewed the recent primary research on the assessment of the extent of microplastics pollution in Bangladesh. From the online databases, we developed a compilation of emerging research articles that detected and quantified microplastics in different coastal, marine, and urban environments in Bangladesh. Most of the studies focused on the coastal environment (e.g., beach sediment) and marine fish, while limited data were available for the urban environment. We also discussed the relationship of the type of anthropogenic activities with the observed microplastic pollution. The Cox’s Bazar sea beach in south-east Bangladesh experienced microplastics pollution due to tourism activities, while fishing and other anthropogenic activities led to microplastics pollution in the Bay of Bengal. While microplastics larger than 1 mm were prevalent in the beach sediments, smaller microplastics with size below 0.5 mm were prevalent in marine fish samples. Moreover, the differences in microplastic abundance, size, shape, color, and polymer type found were depended on the sampling sites and relevant anthropogenic activities. It is imperative to identify major sources of microplastics pollution in both natural and urban environment, determine potential environmental and human health effects, and develop mitigating and prevention strategies for reducing microplastics pollution.     

SO2和NO2胁迫对红花荷等植物光合生理影响及抗性评价

为探讨红花荷(Rhodoleia championii)等12种园林植物抗SO2和NO2污染能力,以1～2年生实生苗为材料,通过人工气候室的盆栽实验,研究不同SO2和NO2混合气体胁迫对园林植物苗木光合参数和相对叶绿素含量的影响,并利用隶属函数法及系统聚类分析法对其抗SO2和NO2污染能力进行了综合评价。结果表明,植物叶片净光合速率、气孔导度、蒸腾速率和相对叶绿素含量基本上随着SO2和NO2胁迫的加剧而逐渐降低,但水分利用效率受净光合速率和蒸腾速率变化的影响规律不明显。综合隶属函数和聚类分析可知,红花荷和红千层(Callistemon rigidus)抗污染能力强,杜鹃红山茶(Camellia azalea)和粉红羊蹄甲(Bauhinia blakeana)抗污染能力较强,红花银桦(Grevillea robusta)和无忧树(Saraca divespierre)抗污染能力中等,大叶紫薇(Lagerstroemia speciosa)、金花风铃木(Tabebuia chrysantha)和腊肠树(Cassia fistula)抗污染能力较弱,而本地火焰木(Spathodea nilotica)、复羽叶栾树(Koelreuteria bipinnata)和樱花(Prunus serrulata)抗污染能力弱。研究结果为火电厂、陶瓷厂、钢铁厂、石化厂等重度酸污染地区植物选择提供参考。     

Biological benthic tools as indicators of coastal marine ecosystems health

Coastal marine ecosystems are increasingly subjected to environmental stress and degradation due to pollution. Several research programmes have addressed this problem and produced relevant data sets for specific areas, often including consistent sets of environmental and biological variables. The value of existing information gathered from these types of data can be largely increased by combining them into a common data set to determine globally applicable relationships. To perform this exercise, the Intergovernmental Oceanographic Commission (IOC) of UNESCO has recently formed the Ad hoc Study Group on Benthic Indicators (http://www.ioc.unesco.org/benthicindicators) with the aim of developing robust indicators of benthic health. In this paper, initial products and ongoing activities of this international initiative are described and discussed. An expansion of initial IOC/UNESCO research on benthic fauna-organic carbon relationships is also presented. As part of this follow-up research, the relationship between total organic carbon concentrations of sediment and abundance, biomass and species diversity of benthic macrofauna was evaluated using data sets from 2 different regions of the world comprising 3 different coastal marine environments. The ability of identifying threshold levels in selected variables that could serve as indicators of related adverse environmental conditions leading to stress in the benthos is envisaged within the frame of a larger joint analysis, carried out by the IOC/UNESCO Study Group on Benthic Indicators, of merged data sets from several coastal regions worldwide.