Predicting the relative oral bioavailability of naturally occurring As,Cd and Pb from in vitro bioaccessibility measurement: implications for human soil ingestion exposure assessment

Environmental Geochemistry and Health - Chestnut soils developed over mineralized areas of southwestern Spain are characterized by high baseline concentrations of geogenic trace elements, notably...     

Benefits of protected areas for nonbreeding waterbirds adjusting their distributions under climate warming

Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993–2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTI_SD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTI_SD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTI_SD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming.     

Movements of blue sharks (Prionace glauca) in depth and course

Acoustic telemetry was used to follow 22 blue sharks,Prionace glauca (Linnaeus), over the continental shelf and slope in the region between George's Bank and Cape Hatteras between 1979 and 1986. The sharks frequently made vertical excursions between the surface and depths of several hundred meters. The oscillations, which were repeated every few hours, were largest in the daytime and were smaller in amplitude and confined to depths near the thermocline at night. This behavior was prominent in trials from August through March, but was not seen from June through July. Diving is discussed in terms of a hunting tactic and behavioral thermoregulation. Most of the sharks moved in a southeasterly direction from the release point and many maintained a constant course day and night for several days. The sharks may orient to the earth's magnetic field, or to the ocean's electric fields, allowing them to swim on a constant heading in the absence of celestial cues. These possibilities are discussed in the appendix.     

Accumulation of mesozooplankton in a wake area as a causative mechanism of the “island-mass effect”

Mesozooplankton biomass (as displacement volume and protein content) and electron-transport system (ETS) activity have been studied in the coastal waters around the Canary Islands. Increases in biomass and ETS activity, on a unit volume basis, were observed in the wakes of the islands. The biomass values obtained in the leeward area for Gran Canaria Island were up to ten times higher than those observed for typical oceanic waters around this archipelago. Sampling was performed in May 1986 at the end of the characteristic vertical mixing period in these waters. Relatively strong winds were recorded prior to sampling. Specific ETS activity was higher at the windward stations on the island shelf. This correlates with the observation in a recent study of increased primary production on the shelf area, where turbulence produced by the northerly trade winds has a marked effect. The persistence of this turbulence during a prolonged wind-pulse results in an accumulation of organisms in the wake of the islands due to current dynamics. This process is proposed as being an important causative mechanism of the island-mass effect. Different biomass values were recorded between circular and oblong islands. The latter are oriented towards the current and the northerly trade winds, and display significantly lower biomass values than the former.     

Relation of RNA/DNA ratios to growth for the scallop Euvola (Pecten) ziczac in suspended culture

We examined the relation of RNA/DNA ratios to growth for three size groups of the tropical scallop Euvola ziczac maintained in suspended culture at 8, 21 and 34 m in depth in the Golfo de Cariaco, Venezuel. Various growth parameters indicated that production decreased with depth. This was more likely due to a decrease in seston quality with depth than to temperatures or seston abundance (which were similar at the various depths studied). The RNA/DNA ratio was correlated with the G-index of muscle growth for juveniles (r ²=0.55). A much weaker correlation was observed for the maturing scallops (r ²=0.18), probably because of the interaction between reproductive and somatic growth. In fully mature scallops, somatic growth was negligible and the RNA/DNA ratios appeared to be inversely related to the level of physiological stress of the scallops. Whereas RNA/DNA ratios are difficult to interpret for maturing E. ziczac, because an increased ratio can be due to either increased gonadal or somatic growth, they are useful in predicting growth in juveniles and physiological stress in fully mature scallops.     

Nucella lapillus L. imposex levels after legislation prohibiting TBT antifoulants: temporal trends from 2003 to 2008 along the Portuguese coast

Nucella lapillus (dog whelk) imposex levels were assessed along the mainland Portuguese coast in 2006 and 2008 and were compared with available data from 2003 for the same area. Given that specimen size has been described as a factor inducing variation in some of the imposex assessment indices, and thus resulting in less reliable results, new monitoring and data analysis procedures are described and applied to study change of imposex levels from 2003 to 2008. A significant decline in imposex intensity was observed in the study area during the study period, and the Portuguese coast ecological status (under the terms defined by the OSPAR Commission) notably improved after 2003, confirming the effectiveness of the Regulation (EC) No. 782/2003 in reducing TBT pollution. Nevertheless, N. lapillus populations are still extensively affected by imposex, and fresh TBT inputs were detected in seawater throughout the coast in 2006. These recent inputs are attributed to vessels still carrying TBT antifoulants applied before 2003, as their presence in vessels was only forbidden in 2008. Considering that Regulation (EC) No. 782/2003 is an anticipation of the IMO global ban entered into force in September 2008, a worldwide-scale decrease in TBT pollution can be expected in the near future.     

Reproductive cycle of two commercial species of sea cucumber (Echinodermata: Holothuroidea) from Caribbean Panama

The reproductive status of the holothuroid species Isostichopus badionotus (Selenka, 1867) and Holothuria mexicana (Ludwig, 1875) was studied over 16 months in Bocas del Toro (Panama), from November 1999 to February 2001. Sexual reproduction was evaluated by the gonad index method, and by histology of gonad development. In addition, population structure was assessed based on sex ratio, minimum reproductive size, and length and weight distributions of males and females. The sex ratio in both species was 1:1, with a unimodal population distribution composed mainly of mature individuals. The minimum reproductive length and weight were 13-20 cm and 150 g, respectively, for both species, although reproductive individuals 10 cm in length were also found. A consistently higher gonad index was observed in H. mexicana, due to a high proportion of mature females and males and high gonad indices in most monthly samples. Gametogenesis and spawning patterns seemed to occur throughout the year, with periods of enhanced activity. Two periods of maximum reproductive activity were tentatively identified: July-November for I. badionotus and February-July for H. mexicana, but neither species had a single, sharply defined annual spawning event. Further work on these exploited holothuroids should examine the relationships between reproduction and environmental factors and between reproductive status and recruitment.     

Chemical defense: incorporation of diet-derived pyrrolizidine alkaloid into the integumental scales of a moth (<Emphasis Type="Italic">Utetheisa ornatrix</Emphasis>)

Summary. Evidence is presented that pyrrolizidine alkaloid acquired by Utetheisa ornatrix (Lepidoptera, Arctiidae) as a larva from Crotalaria foodplants is incorporated in part into the scales of the adult. A single forewing of a male or female moth may contain in the order of 6 to 13 g monocrotaline in its scale cover or about 1 to 2% of the moths systemic monocrotaline content. Based on estimates of the number of scales per forewing, the monocrotaline content of individual scales is calculated to be in the order of 0.1 and 0.2 ng monocrotaline per male and female scale, respectively. This amounts to concentrations of about 1 and 3%, values roughly at a par with the average systemic concentration (0.5-0.6%) previously determined for monocrotaline in Utetheisa. It is argued that the presence of pyrrolizidine alkaloid in the moths scale coating could account for the promptness with which adult Utetheisa are rejected by spiders. It is suggested further that chemical impregnation of scales with substances deterrent to predators may be more widespread among insects than generally assumed.     

Diel and seasonal changes in the distribution of fish on a southeast Brazil sandy beach

The effect of diel and seasonal changes in the distribution of fishes on a subtropical sandy beach on the southeastern coast of Brazil were studied. Seine netting was carried out on both seasonal and diel scales between July 1998 and June 1999. A total of 46 fish species was recorded, six being numerically dominant: Anchoa tricolor, Gerres aprion, Harengula clupeola, Atherinella brasiliensis, Mugil liza and Diapterus rhombeus. Seasonal changes in abundance of dominant species were detected. Species dominant in winter were Anchoa tricolor, H. clupeola and Atherinella brasiliensis; in spring, Anchoa tricolor and G. aprion; in summer G. aprion and D. rhombeus; and in autumn M. liza and H. clupeola. Overall, diel patterns did not reveal any significant trends; however, if we consider each season separately, an increase in A. tricolor abundance was recorded during the day in winter/spring, being replaced at night by H. clupeola in winter, and by G. aprion in spring. Increases in number of individuals and biomass at sunset, and decreases during the night were recorded. The winter/spring inshore/offshore movements at diel scale performed by the three most abundant species demonstrate that diel fluctuation acts more at a species-specific level than at a structural one; in summer there was no evidence of diel movements due to a heavy influx of G. aprion and D. rhombeus, which use the area throughout day and night, increasing overall abundance. Seasonal movements seems to be related to ontogenetic change in species, while diel movements in the fish assemblage seem to be more related to physiological requirements, such feeding activity of each particular species, than to physico-chemical conditions.Communicated by O. Kinne, Oldendorf/Luhe