Morphological, physiological and reproductive conditions of rafting bull kelp (Durvillaea antarctica) in northern-central Chile (30°S)

The bull kelp Durvillaea antarctica is a common floating alga in the southern hemisphere, but despite the ecological and biogeographic importance of kelp rafts, little is known about the responses of detached kelps to the conditions at the sea surface. The morphological, physiological and reproductive performances of D. antarctica rafts in the Coastal System of Coquimbo, Chile (CSC, ~30°S), were examined during winter and summer of two successive years (2010/11 and 2011/12). Epibionts (Lepas spp.) that only attach to floating objects were used as indicator for the floating time of kelp rafts. Photosynthetic efficiency and reproductive maturity of both benthic and floating algae varied seasonally, with a stronger decrease in summer than in winter. Blade size (measured as weight proportion of kelp individuals), phlorotannin concentrations and antioxidant activities were lower in floating than in benthic algae. Environmental conditions and floating time affected the blade tissues, with stronger negative effects during summer. These results confirm that floating persistence of D. antarctica in the CSC is suppressed during the summer months, which indicates that the dispersal potential of this (and other) floating algae varies seasonally.     

Annual life cycle of the copepod<Emphasis Type="Italic"> Eucalanus inermis</Emphasis> at a coastal upwelling site off Mejillones (23°S), northern Chile

Eucalanus inermis is an abundant species in the eastern tropical and subtropical South Pacific, including the oceanic and coastal waters off Chile and Peru. Its annual life cycle was studied through a time-series sampling (weekly intervals) during 2002, at a fixed coastal station at an upwelling site (Mejillones Bay, 23°S) off northern Chile. The more-or-less continuous occurrence and abundance of naupliar and copepodid stages indicated that the species reproduces during most of the year, with two peaks: one during the austral spring and the other during the summer. Thereafter, an abrupt decline in the population was observed during winter. The abundances of E. inermis copepodids and nauplii were positively correlated with sea surface temperature, suggesting temperature-dependent development and growth during the spring–summer period. Three cohorts could be distinguished during one annual cycle, with generation times >30 days. The estimate of mean weight-specific daily growth (0.12 day^–1) is lower than that of other species in the area, but it is consistent with a slower development rate. The distribution of this copepod is associated with the equatorial subsurface waters characterized by low-oxygen content (<0.5 ml l^–1). The ascent of this water mass to the near-surface during coastal upwelling in the spring–summer period and the presence of E. inermis adults favor their reproduction and the development of cohorts in the food-rich upwelling environment. The wintertime disappearance of E. inermis from shallow waters is, thus, interpreted as a movement to deep waters (>200 m depth), probably in a lethargic mode, within the oxygen minimum zone in the adjacent oceanic area.Communicated by P.W. Sammarco, Chauvin     

The life cycles of two coexisting copepods, <Emphasis Type="Italic">Calanus chilensis</Emphasis> and <Emphasis Type="Italic">Centropages brachiatu</Emphasis>s,in the upwelling zone off northern Chile (23°S)

A time series study of the copepods Calanus chilensis and Centropages brachiatus was carried out at the coastal upwelling zone of Mejillones (23°S, northern Chile), to analyze their annual life cycles in association with upwelling variation. These species co-exist in the upwelling zone. Weekly sampling of zooplankton and oceanographic variables including Chlorophyll-a and phytoplankton composition were obtained during January–December 2002 at a fixed station (ca. 90 m depth). Stages of abundances, their proportions, changes in body length of adult females, sex ratio and egg production rate (EPR), were used as proxies to examine copepods’ demography. Upwelling, assessed by weekly Ekman transport and oceanographic conditions, was intermittent throughout the year with lack of periodicity components. Populations of both copepod species did not correlate with these non-predictable upwelling events. C. chilensis reproduced year-round and the population showed ca. 15 peaks of adults with an average time interval between peaks of 20 days. C. brachiatus showed a similar life cycle, also having 15 peaks of adults at about 22 days of time intervals. Cross-correlation functions and spectral analysis showed that both populations correlated positively through time, but not in phase, evidencing a time lag for their reproductive cycles. The lag was also evident in their population abundances. Both species differ in their development rates and this may result in non-in phase life cycles. Our findings suggest that species-dependent attributes, such as development rates, modulated by adaptations to temperature, might impose constraints in the species life cycles determining the population cycles. Such attributes must be considered when modeling and understanding population dynamics and secondary production of copepods.     

Diversity and community composition of phosphorus accumulating organisms (PAOs) in the sediments of the Sanshiliujiao Lake reservoir北大核心CSCD

The diversity and community composition of phosphorus accumulating organisms (PAOs) in the sediments of the Sanshiliujiao Lake reservoir in Pingtan island, Fujian Province, were investigated by terminal restriction fragment length polymorphism (T-RFLP) methods combined with the construction of clone libraries. The diversity of PAOs in summer samples was significantly higher than that in winter. The dominant terminal restriction fragments (T-RFs) of PAOs were in the range of 200 to 300 bp in summer, while they were in the range of 150 to 200 bp in winter. Cloning sequencing and phylogenetic analysis showed that the main phyla of PAOs in the sediment of the Sanshiliujiao Lake reservoir were Proteobacteria, Actinobacteria, and Acidobacteria. Anaeromyxobacter, Azospirillum, Microlunatus phosphovorus, and Burkholderia were the dominant genera in the summer samples. Anaeromyxobacter, Methylobacterium, Solibacter, Azospirillum, and Microlunatus phosphovorus were the dominant genera in sediment samples in winter. The results of this study demonstrated that the diversity and community composition of PAOs in the sediments of the Sanshiliujiao Lake reservoir had specific seasonal characteristics. Various forms of phosphorus also showed their influence on the diversity of PAOs, especially Fe/Al-P. Our findings lays a scientific foundation for the future disclosure of microbial mechanisms involved in the phosphorus metabolic cycle in the sediments of reservoirs. © 2018 Science Press. All rights reserved.     

Characterization of the lignin signature in Lake Mead,NV, sediment: comparison of on-line flash chemopyrolysis (600°C) and off-line chemolysis (250°C)

The distribution of lignin in sediment is a useful tool for tracing the transport of land-derived organic matter in an aquatic environment. Tetramethylammonium hydroxide (TMAH) flash chemopyrolysis, or chemolysis followed by GC–MS analysis can be used for evaluating the origin of organic carbon in sediments. TMAH chemopyrolysis or chemolysis of organic matter produces a myriad of semi-volatile products. Among these products are methylated phenols which are an indirect measure of lignin in sediment. In this study, total organic carbon, elemental carbon, and lignin were measured in Lake Mead sediments. This study indicates that terrestrial runoff makes a contribution to Lake Mead sediments, and that this contribution is most apparent in sediment that is close to the Las Vegas Wash. Two chemolysis methods (on-line and off-line) were examined and compared for detection of lignin phenols. The results from these sediment cores indicate that comparable results can be obtained from the two approaches, although detection levels are significantly lower for the off-line approach.     

Accumulation and transfer of Hg, As, Se, and other metals in the sediment-vegetation-crab-human food chain in the coastal zone of the northern Brazilian state of Pará (Amazonia)

The high consumption of crabs (Ucides cordatus) stimulated interest in the present study on the northern coast of Brazil, which encompasses a preserved area of mangrove forest. The objective was to describe and quantify the transfer of metals from the muddy sediments to the leaves of the Rhizophora mangle, and thence the crabs and humans. The samples were collected along two transects, while samples of hair were obtained from local habitants. The pH, interstitial salinity, Eh (mV) were measured, the granulometry and mineralogical and multi-element chemical analyses were run, and the organic material determined. The sediments are silty-clayey, composed of quartz, kaolinite, iron oxides, and illite, as well as smaller portions of smectite, pyrite, halite, and high levels of SiO₂ (56.5 %), Al₂O₃ (18.5 %), and Fe₂O₃ (7 %). The elements Zn, Sr, As, and Zr are concentrated in the leaves, while the bioaccumulation of Zn, Se, Sr, and As was recorded in the crabs, of which, Se is the most concentrated in the tissue of the muscles and the hepatopancreas. The concentrations of nutrient and toxic elements were similar in all age groups (hair samples), with only Hg presenting an increasing concentration between infants and adults. The highest rates of transfer were recorded for the elements Zn and Se in the crabs and Hg in leaves and hair. The accumulation of metals in the leaves and crabs reflects the chemical composition of the sediments and low rates of sediment-vegetation-crab transfer, with the exception of Hg, which accumulated in the hair.     

The scent of alarm: ontogenetic and genetic variation in the osmeterial gland chemistry of Papilio glaucus (Papilionidae) caterpillars

Within a species, ontogenetic and genetic variation in defensive chemistry can provide the basis for natural selection from different predator types. The osmeterial chemistry of fifth (last) instar Papilio glaucus caterpillars is known to differ qualitatively from the composition of early instar caterpillars. However, the osmeterial chemistry of early instar caterpillars has not been thoroughly characterized and may change as the caterpillars undergo their first three molts. We have used GC/MS to identify a suite of about 50 different terpene compounds in the osmeterial secretions of P. glaucus caterpillars, and found the relative amounts of these compounds changed significantly with each molt. These quantitative changes preceded the more dramatic qualitative switch to the production of 2-methylbutyric and isobutyric acids after the molt to the fifth instar. We also examined the effects of diet and genetic background on the relative quantities of 15 terpenes present in the secretions of third instar caterpillars. Parentage was found to affect the percentages of many more of the individual components than did diet, although both exerted an effect. The ontogenetic and genetic variations in the composition of the osmeterial secretions appear to have an effect on would-be predators. In the laboratory, terpene secretion was found to discourage attack by ants, whereas the switch from terpene to acid production rendered the caterpillars less palatable to a larger predator, the green anole. In the field, the presence of functional osmeteria did not seem to dramatically increase survival in a field study, and only a small, non-significant advantage was seen. Similarly, field data was suggestive that parentage might affect the likelihood of survival in a natural setting, but the stage of the caterpillar and the field site significantly affected survivorship. Further studies with greater replicates will be needed to determine whether and to what extent chemical differences in osmeterial components as well as behavior contribute to differences in outcomes in the field.     

Spatial and social connectivity of fish-eating “Resident” killer whales (Orcinus orca) in the northern North Pacific

The productive North Pacific waters of the Gulf of Alaska, Aleutian Islands and Bering Sea support a high density of fish-eating “Resident” type killer whales (Orcinus orca), which overlap in distribution with commercial fisheries, producing both direct and indirect interactions. To provide a spatial context for these interactions, we analyzed a 10-year dataset of 3,058 whale photo-identifications from 331 encounters within a large (linear ~4,000 km) coastal study area to investigate the ranging and social patterns of 532 individually identifiable whales photographed in more than one encounter. Although capable of large-scale movements (maximum 1,443 km), we documented ranges generally <200 km, with high site fidelity across summer sampling intervals and also re-sightings during a winter survey. Bayesian analysis of pair-wise associations identified four defined clusters, likely representing groupings of stable matrilines, with distinct ranging patterns, that combined to form a large network of associated whales that ranged across most of the study area. This provides evidence of structure within the Alaska stock of Resident killer whales, important for evaluating ecosystem and fisheries impacts. This network included whales known to depredate groundfish from longline fisheries, and we suggest that such large-scale connectivity has facilitated the spread of depredation.     

The concentration of Cu and Pb in the funnel spider Eratigena atrica (C. L. Koch 1843) (Araneae: Agelenidae) and its web

Studies on the heavy metal concentrations on spider webs in relation to the pathways of pollution penetration (external and internal) have yet to be performed. This work assesses the concentration levels of two heavy metals: essential copper (Cu) and toxic lead (Pb) in spider webs and spiders (females, males and juveniles). Spiders divided into three treatment groups were exposed to the heavy metals in their diet as prey (fruit flies and mealworms larvae) were artificially contaminated with Cu and Pb. In general, we found higher rates of Cu compared to Pb concentrations in spiders and their webs. A positive correlation between levels of Cu and Pb in webs and spiders was found. Males had higher concentrations of both metals Cu and Pb in their bodies and webs compared to females. In an additional experiment, washed webs had significantly less metals than unwashed suggesting the dominance of external pollution in the contamination pathway.     

Concentration of ascorbic acid and innate immune effectors in <Emphasis Type="Italic">Engraulis ringens</Emphasis> and <Emphasis Type="Italic">Strangomera bentincki</Emphasis> during their main spawning period (2007–2008) in the Humboldt current system off Chile

In this study, we determined variations in ascorbic acid (AA) concentrations in the gonads and liver, and of the innate immune response (lysozyme activity and antiprotease) in the plasma of Engraulis ringens (anchoveta) and Strangomera bentincki (common sardine) during their reproductive seasons of 2007 and 2008 in the central area of the Humboldt Current. During the main spawning season in 2007, colder environmental conditions, higher phytoplankton biomasses, low dinoflagellate abundance and the dominance of large copepods in winter-early spring and of small copepods in late spring contributed to explain higher AA concentrations in anchoveta tissues. During the warmer year of 2008, lower phytoplankton biomasses, a notable increase of dinoflagellate abundance and the dominance of small-size copepods in winter and of larger copepods in spring occurred along with a drastic drop in AA concentrations in anchoveta tissues. These results contrasted with those in common sardine, a species in which AA did not vary as much as in anchoveta. An inverse trend between AA concentration in the liver and the gonadosomatic index suggested the AA utilization during gonadic maturation. Innate immune parameters were determined for the first time in small pelagic fish and constitute a new baseline data to evaluate their natural response to environmental changes. Changes in the distribution and abundance of edible taxa containing AA and edible for fish along with variations in AA in fish tissues during their reproductive season could become good indicators of the overall fish physiological condition resulting from variations in the trophic web structure.     

Comparative biochemical composition of ploidy groups of the lion-paw scallop (<Emphasis Type="Italic">Nodipecten subnodosus</Emphasis> Sowerby) supports the physiological hypothesis for the lack of advantage in triploid mollusc’s growth in food-rich environments

Induction of triploidy in aquatic organisms has increased worldwide in the last two decades, mostly because triploids have better growth than diploids. According to a physiological hypothesis, partial or total sterility of triploids allows the accumulation of reserves in muscle and other tissues instead of being transferred to the gonad. The present study analyzes lipid, protein, carbohydrate, and fatty acid levels in muscle and gonads of Nodipecten subnodosus triploids and diploids over 18 months from June 2001 to December 2002. An important increase in gonadosomatic index of diploids scallops was observed from May to June 2002 reaching the highest values in August. Such increase was not observed in triploid scallops. Changes in biochemical composition in female gonad were in general related to the accumulation of reserves during gonad development of diploid scallops. This accumulation was lower for triploid scallops, in accordance to their sterility, especially for carbohydrates and acylglycerides. Adductor muscle index as well as protein and carbohydrate levels in muscle increased in both ploidy groups during the reproductive period indicating no mobilization of reserves to sustain gonad development in both ploidy groups. These results partially support the physiological hypothesis on the advantage of triploids: in a rich food locality no mobilization of reserves is needed to sustain gametogenesis. This, together with a possible lower efficiency of energy assimilation at high food concentration for triploids, may be the reason for an apparent lack of superiority of N. subnodosus triploids in terms of adductor muscle growth. Only the levels of particular highly unsaturated fatty acids levels (namely 20:4n-6 and 20:5n-3) in muscle of diploid and triploid decreased during the reproductive period, indicating a possible transfer of selected fatty acids to gonads, even in triploids. The muscle of triploids has a slightly but significantly higher proportion of 22:6n-3 compared to diploids, which can have implications for the nutritional and commercial value of triploid adductor muscle.     

The As-Contaminated Elqui River Basin: a Long Lasting Perspective (1975–1995) Covering the Initiation and Development of Au–Cu–As Mining in the High Andes of Northern Chile

The Elqui watershed (northern Chile) constitutes a highly contaminated river system, with arsenic exceeding by up to three orders of magnitude the average for river waters. There are three main reasons that explain this contamination: (1) the regional geology and hydrothermal (mineralizing) processes that developed in this realm during Miocene time; (2) the later unroofing–erosion–oxidation–leaching of As–Cu rich sulfide ores, a process that have been taking place for at least 10,000 years; and last but not least (3) mining activities at the high-altitude (>4000 m above sea level) Au–Cu–As El Indio mine, from the late 1970s onwards. The El Indio mineral deposit hosted large veins of massive sulfides, including the important presence of enargite (Cu₃AsS₄). The continuous natural erosion of these veins and their host rocks (also rich in As and Cu) during Holocene time, led to important and widespread metal dispersion along the river system. During the studied pre mining period (1975–1977), the high altitude river Toro waters already showed very large As concentrations (0.36–0.52 mg l⁻¹). The initiation of full scale mining at El Indio (1980 onwards) led to an increase of these values, reaching a concentration of 1.51 mg l⁻¹ As in 1995. During the same year other rivers of the watershed reached peak As concentrations of 0.33 (Turbio) and 0.11 mg l⁻¹ (Elqui). These figures largely exceed the USEPA regulations for drinking water (0.01 mg l⁻¹ As), and about 10% of the total As data from the river Elqui (and 70% from the river Turbio) are above the maximum level allowed by the Chilean law for irrigation water (0.1 mg l⁻¹ As).     

Reproductive biology and population structure of the deep-sea hydrothermal vent worm Paralvinella grasslei (Polychaeta: Alvinellidae) at 13°N on the East Pacific Rise

Paralvinella grasslei is a polychaetous annelid living in the harsh, unstable and heterogeneous environmental conditions found at deep-sea hydrothermal vent sites in the eastern Pacific. The aim of this work was to examine the possible influence of the reproductive biology of P. grasslei on the structure of its populations. Maximum observed oocyte size inside the oviduct is 275 m, and fecundity is relatively low. Examination of gametes and young specimens suggested a direct benthic development for this species. The population structure of P. grasslei at 13°N/EPR (EPR=East Pacific Rise) revealed a discontinuous recruitment which seems to be synchronized within vent sites and fields. The data also suggested the occurrence of discrete breeding periods. P. grasslei probably reproduces several times a years, with an apparent periodicity. Tidal signals could be a possible cue for the coordination of the reproductive cycle. The life-history of P. grasslei is discussed in light of the reproductive biology of other terebellomorph polychaetes, and seems to be well adapted for colonizing the unstable environment of hot vents. Two main hypotheses can explain the dissemination processes of this species along axial oceanic ridges. The influence of nearbottom currents occurring along the central graben of the East Pacific Rise can be cosidered to account for part of the transport of larvae and juveniles, but the observations of polychaete erpochaetes on the test of hydrothermal bythograeid crabs and evidence that crab migrations occur between vents also support the possibility of zoochory for the dissemination of alvinellid polychaetes.     

Cryptobenthic fishes of the “Ciclopi Islands” marine reserve (central Mediterranean Sea): assemblage composition,structure and relations with habitat features

The fish assemblage of the Ciclopi Islands marine reserve, which is located along the eastern coast of Sicily (Central Mediterranean), was unknown until our study provided insight into the cryptobenthic fish assemblage inhabiting this integral reserve zone. Visual census surveys were periodically conducted along the littoral rocky shores of Lachea, the largest island of the Ciclopi archipelago. The fish assemblage, which comprised 20 species belonging to Blenniidae, Gobiidae, Tripterygiidae, Scorpaenidae and Gobiesocidae, was dominated by Scorpaena maderensis and Trypterigion delaisi. Species richness (S) did not show significant differences between the northern, eastern, southern and western island coasts, whereas both species diversity (H) and evenness (J) were significantly higher on the western coast than on the northern coast. The effect of the island coast on fish density was not significant with regard to the whole assemblage or to single species, except for S. maderensis and T. delaisi. The pattern of variation of assemblage parameters was mainly positively correlated with microhabitat variables, especially substratum composition and type of cover. The best predictors of fish total density were bottom slope, rugosity and substratum composition. Variations in relative species density were specified by a different combination of macro- and microhabitat variables. The density pattern of S. maderensis showed a positive relationship with depth. In T. delaisi, the influence of slope was interrelated to that of exposure to waves. This species preferentially inhabited flat habitat, sheltered from the open sea and covered by small boulders, but also more-exposed rockwalls. The population densities of Tripterygion melanurus and Lipophrys trigloides were negatively affected by depth, thus reflecting their preference for the upper infralittoral. T. melanurus was associated with a more complex habitat (stones and boulders), whereas L. trigloides was mainly censused on a narrow strip of solid rock between the waterline and 1 m depth.Communicated by R. Cattaneo-Vietti, Genova     

Review of total suspended particles (TSP) and PM<Subscript>2.5</Subscript> concentration variations in Asia during the years of 1998–2015

In Asian countries such as China, Malaysia, Pakistan, India, Taiwan, Korea, Japan and Hong Kong, ambient air total suspended particulates and PM_2.5 concentration data were collected and discussed during the years of 1998–2015 in this study. The aim of the present study was to (1) investigate and collect ambient air total suspended particulates (TSP) and PM_2.5 concentrations for Asian countries during the past two decades. (2) Discuss, analyze and compare those particulates (TSP and PM_2.5) annual concentration distribution trends among those Asian countries during the past two decades. (3) Test the mean concentration differences in TSP and PM_2.5 among the Asian countries during the past decades. The results indicated that the mean TSP concentration order was shown as China > Malaysia > Pakistan > India > Taiwan > Korea > Japan. In addition, the mean PM_2.5 concentration order was shown as Vietnam > India > China > Hong Kong > Mongolia > Korea > Taiwan > Japan and the average percentages of PM_2.5 concentrations for Taiwan, China, Japan, Korea, Hong Kong, Mongolia and Other (India and Vietnam) were 8, 21, 6, 8, 14, 13 and 30%, respectively, during the past two decades. Moreover, t test results revealed that there were significant mean TSP and PM_2.5 concentration differences for either China or India to any of the countries such as Taiwan, Korea and Japan in Asia during the past two decades for this study. Noteworthy, China and India are both occupied more than 60% of the TSP and PM_2.5 particulates concentrations out of all the Asia countries. As for Taiwan, the average PM_2.5 concentration displayed increasing trend in the years of 1998–1999. However, it showed decreasing trend in the years of 2000–2010. As for Korea, the average PM_2.5 concentrations showed decreasing trend during the years of 2001–2013. Finally, the average PM_2.5 concentrations for Mongolia displayed increasing trend in the years of 2004–2013.     

Differences in diet composition and foraging patterns between sexes of the Magellanic penguin (Spheniscus magellanicus) during the non-breeding period as revealed by δ13C and δ15N values in feathers and bone

In diving seabirds, sexual dimorphism in size often results in sex-related differences of foraging patterns. Previous research on Magellanic penguins, conducted during the breeding season, failed to reveal consistent differences between the sexes on foraging behavior, despite sexual dimorphism. In this paper, we tested the hypothesis that male and female Magellanic penguins differ in diet and foraging patterns during the non-breeding period when the constraints imposed by chick rearing activities vanish. We used stable isotope ratios of carbon and nitrogen in feather and bone to characterize the diet and foraging patterns of male and female penguins in the South Atlantic at the beginning of the 2009–2010 and 2010–2011 post-breeding seasons (feathers) and over several consecutive breeding and migratory seasons (bone). The mean δ¹³C and δ¹⁵N values of feathers showed no differences between the sexes in any of the three regions considered or in the diet composition between the sexes from identical breeding regions; however, Bayesian ellipses showed a higher isotopic niche width in males at the beginning of the post-breeding season. Stable isotope ratios in bone revealed the enrichment of males with δ¹³C compared with females across the three regions considered. Furthermore, the Bayesian ellipses were larger for males and encompassed those of females in two of the three regions analyzed. These results suggest a differential use of winter resources between the sexes, with males typically showing a larger diversity of foraging/migratory strategies. The results also show that dietary differences between male and female Magellanic penguins may occur once the constraints imposed by chick rearing activities cease at the beginning of the post-breeding season.     

Natural feeding activity of the crab Callinectes ornatus (Portunidae) in Ubatuba Bay (São Paulo, Brazil): influence of season, sex, size and molt stage

The natural diet of Callinectes ornatus in Ubatuba Bay, Ubatuba (SP), Brazil, was studied. Influence of season, sex, size and molt stage variation in the diet were also described. Specimens were collected monthly over a period of 1 year, in Ubatuba Bay, using a fishing boat equipped with a double rigged net. The relative degree of stomach fullness, frequency of occurrence, and quantitative scoring (percentage) were determined. Digested material, crustaceans, sediment and mollusks were the principal items of the diet. Echinoderms, annelids, plants, and fishes were also notable prey items, and other food categories (foraminiferans, cnidarians, worms and bryozoans) occurred in low percentages. A non-significant difference was found in many items during seasonal analysis, i.e. plants, foraminiferans, cnidarians, bryozoans and digested material were present at highest percentages during summer and autumn, while crustaceans and echinoderms were consumed in larger amounts during the spring and winter. Males and females consumed a similar diet, although ovigerous females showed a greater tendency to feed on items with soft tissues (fish, squid, shrimp). Juveniles fed more on sedentary and calcareous items than did adults, showing a significant tendency to reduce consumption of foraminiferans, annelids, bryozoans, echinoderms and sediment as the animal increased in size, accompanied by an elevation in the consumption of plants, crustaceans and fish. These crabs are opportunistic predators with a preference for crustaceans and mollusks that is correlated with the availability of prey and the ontogenetic phase of the predator. Received: 21 January 2000 / Accepted: 2 October 2000     

Impacts of temperature and acidification on larval calcium incorporation of the spider crab <Emphasis Type="Italic">Hyas araneus</Emphasis> from different latitudes (54° vs. 79°N)

The combined effects of ocean warming and acidification were compared in larvae from two populations of the cold-eurythermal spider crab Hyas araneus, from one of its southernmost populations (around Helgoland, southern North Sea, 54°N, habitat temperature 3–18°C; collection: January 2008, hatch: January–February 2008) and from one of its northernmost populations (Svalbard, North Atlantic, 79°N, habitat temperature 0–6°C; collection: July 2008, hatch: February–April 2009). Larvae were exposed to temperatures of 3, 9 and 15°C combined with present-day normocapnic (380 ppm CO₂) and projected future CO₂ concentrations (710 and 3,000 ppm CO₂). Calcium content of whole larvae was measured in freshly hatched Zoea I and after 3, 7 and 14 days during the Megalopa stage. Significant differences between Helgoland and Svalbard Megalopae were observed at all investigated temperatures and CO₂ conditions. Under 380 ppm CO₂, the calcium content increased with rising temperature and age of the larvae. At 3 and 9°C, Helgoland Megalopae accumulated more calcium than Svalbard Megalopae. Elevated CO₂ levels, especially 3,000 ppm, caused a reduction in larval calcium contents at 3 and 9°C in both populations. This effect set in early, at 710 ppm CO₂ only in Svalbard Megalopae at 9°C. Furthermore, at 3 and 9°C Megalopae from Helgoland replenished their calcium content to normocapnic levels and more rapidly than Svalbard Megalopae. However, Svalbard Megalopae displayed higher calcium contents under 3,000 ppm CO₂ at 15°C. The findings of a lower capacity for calcium incorporation in crab larvae living at the cold end of their distribution range suggests that they might be more sensitive to ocean acidification than those in temperate regions.     

毒死蜱低剂量重复染毒致学习记忆功能障碍及CREB信号途径的抑制(Repeated Exposures to Low-Level Chlorpyrifos Result in Learning Memory Impairment and Inhibition of the CREB Signal System)

毒死蜱(CPF)是我国推荐使用的低毒有机磷农药之一,目前在全世界广泛应用.选择不引起动物出现全身系统毒性的CPF剂量(1、5、10mg·kg-1)对大鼠连续染毒4周,评价CPF对动物的学习记忆功能和CREB信号通路的影响.结果显示:CPF连续染毒后动物出现记忆能力的损伤,随着染毒剂量的增加,海马、皮质和纹状体CREB及ERKI/Ⅱ磷酸化蛋白表达逐渐减少,这表明ERK/CREB信号通路可能是参与毒死蜱低剂量重复暴露致学习记忆功能改变的重要途径.     

Temporal and vertical distribution of two ecologically different calanoid copepods (<Emphasis Type="Italic">Calanoides carinatu</Emphasis>s Krøyer 1849 and <Emphasis Type="Italic">Lucicutia grandis</Emphasis> Giesbrecht 1895) in the deep waters of the central Arabian Sea

The full-depth vertical distributions of males, females and juveniles of Lucicutia grandis and Calanoides carinatus are presented from the surface down to depths of 3,900 m in the central Arabian Sea at the end of the NE monsoon and the February and October inter-monsoonal periods. L. grandis is a steady component and C. carinatus is a temporal resident of the central Arabian Sea oxygen minimum zone. Maximum abundances of C. carinatus and L. grandis juveniles were found at depths around 600 m, whereas the center of the distribution of L. grandis adults was somewhat deeper at 950 m. Both copepods are indicator species which can help to understand the functioning of the mesopelagic Arabian Sea ecosystem.