Effects of recreational diving on early colonization stages of an artificial reef in North-East Atlantic

Increasing interest for recreational SCUBA diving worldwide is raising the concern about its potential effects on marine ecosystems. Available literature is still much focused either on impacts on coral reefs of tropical regions or on diver’s behaviour underwater. In this study we analysed, through photo-quadrats, the benthic community composition in a section of a decommissioned Portuguese navy ship that was sunk for touristic purposes. The ship broke down and became separated in two sections enabling a Control versus Impact sampling design, as one section is less attractive for diving. Gorgonians (mainly belonging to the species Leptogorgia sarmentosa and Eunicella verrucosa) were the taxa more negatively affected in the dived ship section, with smaller coverage and size. More resilient species such as the acorn barnacle Amphibalanus amphitrite were positively correlated with the Impact samples. In the case of the study area, according to the available data, 70% or more of the total amount of dives are now on the sunken ships. From these results, lessons can be taken to apply on natural reefs and related management plans.     

Influence of overstory removal on growth of epiphytic mosses and lichens in western Oregon.

Will old-growth-associated epiphytes survive if the forest canopy is opened around them by thinning or partial harvest? If old-growth association is due to a species' environmental tolerances, it may not survive in the relatively open stands that result from such treatments. If, however, old-growth association is due to dispersal limitations rather than environmental tolerances, retention of host trees as refugia and sources of inoculum might carry populations of old-growth-associated epiphytes into young stands. We studied growth rates of lichen and moss transplants in a Douglas-fir (Pseudotsuga menziesii) forest (tree ages approximately 55 yr) in western Oregon for nine months before and 27 months after moderate thinning, creation of 0.4-ha patch cuts, and in control areas. We also assessed moss sporophyte production. We contrasted responses of one moss species, Isothecium myosuroides sensu lato, which is ubiquitous in forests of varying ages, with those of another moss, Antitrichia curtipendula, and a lichen, Lobaria oregana, which are both associated with old-growth forests. Both old-growth associates grew faster in thinned areas and patch cuts than in controls, while Isothecuim grew most slowly and produced fewest sporophytes in patch cuts. These species are likely to survive in remnants, assuming they can remain attached, and may be successful in young stands if they can disperse and establish there. Our results suggest that logging with green-tree retention and other silvicultural practices that preserve trees or shrubs hosting the species studied here are likely to encourage these species' development in managed forests.     

The effect of ocean acidification on early algal colonization stages at natural CO2 vents

Marine algae exhibit different responses to ocean acidification, suggesting that a decrease in pH does not always favour marine photosynthetic organisms. In order to understand the effect of acidification on algal community development, early colonization stages were investigated using carbon dioxide vents around the Castello Aragonese (Ischia, Italy) as a natural laboratory. Settlement tiles were placed in zones with different pH (normal, medium and low), and species composition and coverage measured after 2, 3 and 4 months of deployment. The number of species decreased by 4 and 18 % at medium and low pH zones, respectively (P < 0.05). The structure of the algal assemblage differed between pH zones during the 4 months of the experiment, due to the addition and/or replacement of new species. This leads to a change in the succession of morphological forms as soft crustose algae replaced calcareous species, and turf species were dominant in cover; more complex thalli started to occur only at medium pH. These results support previous findings that ocean acidification will induce changes in benthic algal communities.     

Community assembly in the presence of disturbance: a microcosm experiment

Ecologists know relatively little about the manner in which disturbance affects the likelihood of alternative community stable states and how the history of community assembly affects the relationship between disturbance and species diversity. Using microbial communities comprising bacterivorous ciliated protists assembled in laboratory microcosms, we experimentally investigated these questions by independently manipulating the intensity of disturbance (in the form of density-independent mortality) and community assembly history (including a control treatment with simultaneous species introduction and five sequential assembly treatments). Species diversity patterns consistent with the intermediate disturbance hypothesis emerged in the controls, as several species showed responses indicative of a tradeoff between competitive ability and ability to recover from disturbance. Species diversity in communities with sequential assembly, however, generally declined with disturbance, owing to the increased extinction risk of later colonizers at the intermediate level of disturbance. Similarities among communities subjected to different assembly histories increased with disturbance, a result due possibly to increasing disturbance reducing the importance of competition and hence priority effects. This finding is most consistent with the idea that increasing disturbance tends to reduce the likelihood of alternative stable states. Collectively, these results indicate the strong interactive effects of disturbance and assembly history on the structure of ecological communities.     

Larger foraminifera: Reproduction and early stages of development in Heterostegina depressa

The process of reproduction (multiple fission) of the megalospheric gamont of Heterostegina depressa d'Orbigny, 1826 (Nummulitidae) is described. During this process, the protoplasm separates outside the parent test into the juveniles. The initial chambers receive some of the symbiotic algae from the parent protoplasm. The second chamber develops from the initial chamber by division, not by growth. The newly formed 2-chamber-stage receives a second set of symbiotic algae from the parent residual protoplasm. Thereafter, calcification takes place, and the first ectoplasm sheath is formed. The problem of alternation of generations is discussed. From the very small proportion of microspheric individuals found in Heterostegina species (fossil and recent) it is concluded that gamogony has been greatly reduced.     

Spore germination and early stages of development in Hypnea musciformis (Rhodophyta,Gigartinales)

The early stages of development of the carpospores and tetraspores of Hypnea muscilormis (Wulfen) Lamouroux have been investigated. Both types of spores germinated immediately after liberation. The spores segmented repeatedly into, 2, 3, 4 cells, etc. until a multicellular ball of cells was produced. The germination pattern was thus of the discal type, i.e., Typus discalis mediatus (Inoh, 1947) or the Dumontia-type in the terminology of Chemin (1937). Subsequently, a relatively expansive attachment holdfast was produced from each sporeling. This was followed by the development of up to 4 or more shoot axes arising from the basal disc. These findings are discussed with reference to an earlier study by the senior author on the developmental biology of other species of Hypnea Lamouroux.     

Acute toxicities of eleven metals to early life-history stages of the yellow crab Cancer anthonyi

We report findings from the first laboratory experiments to assess toxicities of metals found in drilling muds to embryos and prezoeae of a brachyuran crab. Embryos of Cancer anthonyi are brooded externally on the abdomen of female crabs; thus, embryos may be continuously exposed to pollutants contained in sediments of contaminated benthic habitats. Lethal concentrations of metals to embryos after 7 d exposures were: iron and barium (sulfate), 1 000 mg l^–1; barium (chloride), 100 mg l^–1; aluminum and nickel, 10 mg l^–1; copper and lead, l mg l^–1; cadmium, chromium VI and manganese, 0.01 mg l^–1; mercury, 0.001 mg l^–1. All metals effectively retarded embryos from hatching at concentrations equal or lower to those causing mortality, except for cadmium. Particularly impressive was iron, which suppressed hatching at l to 10 mg l^–1, concentrations previously found non-deleterious to marine organisms and 100 times more dilute than concentrations causing significant embryo mortality. The effects of metals on embryos increased as a function of exposure duration. Embryo mortality was delayed for at least 120 h at concentrations 1.0 mg l^–1, with the exception of mercury. Lethal concentrations established at 96 h were meaningless for crab embryos, because acute toxic thresholds were not attained by that time. Larval survivorship to chromium VI, copper, and zinc increased following exposure of embryos to these metals at low concentrations (1.0 mg l^–1), suggesting induction of biochemical pathways for products which bind or metabolize metals. Identical exposures of embryos to lead failed to enhance subsequent larval survivorship, showing that inductions may be metal-specific. We suggest that exposures of brachyuran embryos at field sites and the success of their subsequent hatching in the laboratory may be a means of assessing environmental contamination otherwise difficult to monitor.     

Density dependence and density independence during the early life stages of four marine fish stocks

Recruitment variability caused by density-dependent and density-independent processes is an important area within the study of fish dynamics. These processes can exhibit nonlinearities and nonadditive properties that may have profound dynamic effects. We investigate the importance of population density (i.e., density dependence) and environmental forcing (i.e., density independence) on the age-0 and age-1 abundance of capelin (Mallotus villosus), northeast Arctic cod (Gadus morhua), northeast Arctic haddock (Melanogrammus aeglefinus), and Norwegian spring spawning herring (Clupea harengus) in the Barents Sea. We use statistical methods that explicitly account for nonlinearities and nonadditive interactions between internal and external variables in the abundance of these two pre-recruitment stages. Our results indicate that, during their first five months of life, cod, haddock, and herring experience higher density-dependent survival than capelin. The abundance of age-0 cod depends on the mean age and biomass of the spawning stock, a result which has implications for the management of the entire cod stock. Temperature is another important factor influencing the abundance at age-0 and age-1 of all four species, except herring at age-1. Between age-0 and age-1, there is an attenuation of density-dependent survival for cod and herring, while haddock and capelin experience density dependence at high and low temperatures, respectively. Predation by subadult cod is important for both capelin and cod at age-1. We found strong indications for interactions among the studied species, pointing to the importance of viewing the problem of species recruitment variability as a community, rather than as a population phenomenon.     

Modelling effects of time-variable exposure to the pyrethroid beta-cyfluthrin on rainbow trout early life stages

Background

Available literature and regulatory studies show that the severity of effects of beta-cyfluthrin (a synthetic pyrethroid) on fish is influenced by the magnitude and duration of exposure. To investigate how the exposure pattern to beta-cyfluthrin (constant vs peak) may influence the response of the fish, we used a mechanistic effect model to predict the survival and growth of the rainbow trout over its early life stages (i.e. egg, alevin and swim-up fry). We parameterized a toxicokinetic–toxicodynamic (TKTD) module in combination with a dynamic energy budget model enabling us to describe uptake and elimination, as well as to predict the threshold concentration for survival and sublethal effects (feeding behaviour and growth). This effect model was calibrated using data from an early life stage experiment where trout was exposed to a constant concentration of cyfluthrin. The model was validated by comparing model predictions to independent data from a pulsed-exposure study with early life stages of rainbow trout.

Results

The co-occurrence of effects on behaviour and growth raised the possibility that these were interrelated, i.e. impairment of feeding behaviour may have led to reduced food intake and slower growth. We, therefore, included ‘effect on feeding’ as mode of action in the TKTD module. At higher concentrations, the constant exposure led to death. The model was able to adequately capture this effect pattern in the calibration. The model was able to adequately predict the response of fish eggs, alevins and swim-up fry, from both the qualitative (response pattern) and quantitative points of view.

Conclusions

Since the model was successfully validated, it can be used to predict survival and growth of early life stages under various realistic time-variable exposure profiles (e.g. profiles from FOCUS surface water modelling) of beta-cyfluthrin.

     

Quantifying dispersal and establishment limitation in a population of an epiphytic lichen

Dispersal is a process critical for the dynamics and persistence of metapopulations, but it is difficult to quantify. It has been suggested that the old-forest lichen Lobaria pulmonaria is limited by insufficient dispersal ability. We analyzed 240 DNA extracts derived from snow samples by a L. pulmonaria-specific real-time PCR (polymerase chain reaction) assay of the ITS (internal transcribed spacer) region allowing for the discrimination among propagules originating from a single, isolated source tree or propagules originating from other locations. Samples that were detected as positives by real-time PCR were additionally genotyped for five L. pulmonaria microsatellite loci. Both molecular approaches demonstrated substantial dispersal from other than local sources. In a landscape approach, we additionally analyzed 240 snow samples with real-time PCR of ITS and detected propagules not only in forests where L. pulmonaria was present, but also in large unforested pasture areas and in forest patches where L. pulmonaria was not found. Monitoring of soredia of L. pulmonaria transplanted to maple bark after two vegetation periods showed high variance in growth among forest stands, but no significant differences among different transplantation treatments. Hence, it is probably not dispersal limitation that hinders colonization in the old-forest lichen L. pulmonaria, but ecological constraints at the stand level that can result in establishment limitation. Our study exemplifies that care has to be taken to adequately separate the effects of dispersal limitation from a limitation of establishment.     

Effects of ocean acidification on the early developmental stages of the horned turban,Turbo cornutus

To estimate the impact of CO₂-driven ocean acidification on the early life stages of gastropods, the effects of increased partial pressure of seawater carbon dioxide (pCO₂) (800–2,000 μatm) on the early developmental stages and larval shell length of the commercially important gastropod, the horned turban snail, Turbo cornutus were investigated. Increase in experimental seawater pCO₂ had an increasingly negative impact on the early developmental rate; the proportion of embryos or larvae displaying retarded development increased at higher pCO₂. The proportion of embryos that developed to the 4-cell stage at 2 h after fertilization decreased linearly with increasing pCO₂. At ~1,000 μatm pCO₂, retarded development was observed in ~50 % of larvae. No embryos developed to the 4-cell stage at 2,000 μatm pCO₂ within 2 h of fertilization. A similar trend continued until 24–26 h after fertilization; the proportion of larvae attaining veliger stage by 24–26 h also decreased with increasing pCO₂. The shell length of T. cornutus veligers decreased gradually as seawater pCO₂ increased, but markedly decreased in seawater under nearly unsaturated and unsaturated conditions (≤1.04) of the aragonite saturation state (Ω _aragonite). The results indicate that increased pCO₂ seawater has a progressive and acute effect on embryonic and larval T. cornutus, and imply that the extended early developmental period and/or the downsized larval shell produced by ocean acidification will have a negative impact on survival, settlement and recruitment well into the future.     

Heavy metal accumulation in lichens growing in north side of Lucknow city, India

Accumulation of Pb, Fe, Cr, Zn, Cd, Ni, Cu and Hg metals in six common lichen species growing on Mangifera indica trees in mango orchard surrounding the north side of the Lucknow city, were analyzed. The study revealed the higher concentration of Pb (3.3 - 15.6 microgg(-1)), Cr (25.6 - 137.5 microgg(-1)), Zn (49.4 - 219.7 microgg(-1)), Cu (10.2 - 66.6 microgg(-1)) and Fe (1748 - 19374 microgg(-1)).     

Fertilization and early developmental stages of eggs of Clupea harengus pallasi n. maris-albi under fresh-water conditions

Eggs of the White Sea herring Clupea harengus pallasi Val. are laid in the intertidal zone, where they are liable to come under the influence of fresh water. The present paper deals with the effect of fresh-water influence on the egg of the White Sea herring, under experimental conditions. In fresh water, egg and sperm are in an unactivated state and, after transfer into sea water, are capable of re-activation, even after 212/ h exposure. The treated eggs develop until the hatching of normal and viable larvae. The number of eggs which are able to complete development depends upon the period of freshwater exposure, although the correlation between the length of that period and survival rates is not very close. Apparently, this is due both to the ability of C. harengus pallasi eggs to develop parthenogenetically and different qualities of eggs (which were obtained from different females). The morphological features of White Sea herring eggs, induced by experimental fresh-water influence, are very similar to those typical for herring eggs of the genus Ilisha, obtained from natural brackish waters. However, such changes are not characteristic of the eggs of forms from natural fresh and brackish-waters.     

Effect of thermal stress and total residual chlorination on early life stages of the mummichog Fundulus heteroclitus

Effects of simultaneous short-term (7.5 to 60 min) thermal stress (24° to 34°C) and total residual chlorination (0.05 to 1.0 mg l^-1) on specific development stages of the mummichog Fundulus heteroclitus (Pisces: Cyprinodontidae), were investigated. For the embryonic stages, the total number of successfully hatched larvae was used as the criterion to measure effect. For the larval stages, survival 24 h after exposure was used. In the embryonic stages, temperature was the most important main variable. Only one embryonic stage (gastrula) was confounded by second-order interactions (temperature x duration of exposure x total residual chlorination). Both 0-day and 7-day-old larval stages showed significant higher-order interactions for all combinations of test parameters, suggesting the presence of synergistic effects of the three main experimental variables.Contribution No. 308 to the Gulf Breeze Environmental Research Laboratory. Contribution No. 183 to the Belle W. Baruch Institute for Marine Biology and Coastal Research.     

环丙沙星(CIP)对鲤鱼早期生长阶段的影响

我们依据经济合作与发展组织的210指导性文件,利用鲤鱼受精卵,进行环丙沙星(CIP)的毒性试验。测试浓度设置为1、100、500、1 000和3 000 μg?L^L-1。我们发现在所有测试组中,暴露于CIP会加速孵化,但在暴露于最高浓度CIP(3000 μg?L^L-1)的测试组,出现了显著的生长下降的现象。在实验的第6天(孵化之后),可以观察到大量增加的肉眼可见的形态异常现象。最高数量肉眼可见的形态异常现象是在自由胚胎和幼虫CIP暴露浓度为100、500、1 000和3 000 μg?L^L-1的测试组中产生的(测试样本的20%~23%)。在所有CIP暴露试验组中,均检测出GST活性的呈逐步降低趋势,但是在CIP浓度为500和3 000 μg?L^L-1的测试组中出现了显著差异(p < 0.01)。其中在大多数测试浓度下,谷胱甘肽过氧化物酶和过氧化氢酶的活性增加(p < 0.01,p < 0.05),而在CIP暴露浓度为500和3 000 μg?L^L-1的测试组,谷胱甘肽还原酶出现活性降低的现象(p < 0.05)。在所有的CIP暴露组中,硫代巴比妥酸活性物质的浓度明显降低(p < 0.01)。可测的CIP最低有效浓度(LOEC)是1 μg?L^L-1。\这些结果表明,孵化过程,早期的个体发育,形态异常的产生,以及鱼类体内的抗氧化和生物转化酶活性和脂质过氧化反应,都会受到CIP影响。
精选自Dana Zivna, Lucie Plhalova, Lucie Chromcova, Jana Blahova, Miroslav Prokes, Misa Skoric, Petr Marsalek, Eva Praskova, Stanislava Stepanova, Zdenka Svobodova. The effects of ciprofloxacin on early life stages of common carp (Cyprinus carpio). Environmental Toxicology and Chemistry: Volume 35, Issue 7, pages 1733–1740, July 2016. DOI: 10.1002/etc.3317
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3317/full
     

How does cod (Gadus morhua) cope with variability in feeding conditions during early larval stages?

Response of mesocosm-reared cod (Gadus morhua L.) larvae to different feeding conditions was investigated in 1988 in two mesocosms: a large basin and a smaller bag enclosure within the basin. The basin was filled with seawater, and a community of naturally occurring plankton developed. Plankton concentrations were monitored, and cod larvae stocked in the enclosures were sampled for determination of growth, survival, and gut content. In the bag, insufficient amounts of energetically favourable prey, as copepod nauplii, led to non-selective ingestion of plankton from a broad range of sizes, including considerable amounts of protozoans (tintinnid and oligotrich ciliates). Growth of larvae from the bag was low, with daily specific growth rates (SGR) less than 2.8% the first 3 wk post-hatch. This was followd by rapid increase of SGR to 21.7%, which coincided with a large increase in availability of copepod nauplii. In the basin, high nauplii concentrations led to SGR of 13.7 to 21.7% from onset of feeding to 16 d post-hatch, respectively. Under such conditions, the larvae were highly selective feeders. At 3 wk post-hatch, survival was 36.7 and 38.3% in the basin and bag enclosure, respectively. To cope with variations in the feeding conditions, the cod larvae were shown to be opportunists when nauplii were scarce, and included plankton from several trophic levels in their diet. When nauplii were abundant, cod larvae realized their high potential for growth. Both opportunism and realization of a high growth potential may enhance survival of the larvae.