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1.
Previous studies on kleptoplasty in sacoglossans have used different methodology to investigate how long the sacoglossans
are able to keep photosynthetically active (functional) chloroplasts. In this study we have used Pulse Amplitude Modulated
Fluorometry to measure the quantum yield of charge separation in photosystem II in dark acclimated cells (ΦIIe) to detect the status of photosynthetic activity. Seven species of sacoglossa, Plakobranchus ocellatus, Elysia timida, Elysia sp, Elysia tomentosa, Thuridilla carlsoni, T. lineolata and Elysiella pusilla, were investigated regarding their ability to retain functional chloroplasts (RFC). The results show three different levels
of RFC’s where P. ocellatus has the longest RFC for more than 11 months, E. timida with a RFC 1/4 than P. ocellatus (almost 3 months) and the rest with RFC’s down to 1/22 of P. ocellatus (up to 15 days). Based on these results, and compared to previous studies, eight different levels of retention abilities
of non-functional and functional chloroplasts in sacoglossans are proposed. As far as we know, this is a novel method studying
chloroplast functionality in sacoglossans. 相似文献
2.
Borgå K Wolkers H Skaare JU Hop H Muir DC Gabrielsen GW 《Environmental pollution (Barking, Essex : 1987)》2005,134(3):397-409
Four seabird species and their prey (zooplankton or fish) were collected in the Barents Sea to determine how dietary exposure, cytochrome P450 (CYP) enzyme activities and sex influenced their hepatic PCB concentrations and accumulation patterns. Five males and five females from each seabird species (little auk (Alle alle), Brunnich's guillemot (Uria lomvia), black guillemot (Cepphus grylle) and black-legged kittiwake (Rissa tridactyla)) were analysed. PCB concentrations could not be explained directly by carbon source (delta13C) or trophic position (delta15N), but by a combination of dietary parameters (delta13C, delta15N, migratory pattern, age) and contaminant metabolism. Contrary to previous studies, the PCB pattern differed among seabirds, with a higher proportion of persistent congeners (% of PCB-153, RPCB-153) in black-legged kittiwake than in auks. The PCB pattern also differed among auks, with little auk as the most efficient biotransformer (highest RPCB-153 values of persistent congeners). Based on high RPCB-153 values, Brunnich's guillemot poorly metabolised ortho-meta-unsubstituted congeners, whereas black guillemot poorly metabolised meta-para unsubstituted congeners. Species-specific differences in PCB biotransformation were confirmed by metabolic indices, where PCB patterns in seabirds were adjusted for PCB pattern in prey. The relative contribution of ortho-meta-unsubstituted congeners to SigmaPCBs decreased with increasing EROD activity. There were no differences in PCB concentrations, PCB patterns or cytochrome P450 enzyme activities between males and females. CYP P450 activities (CYP1A- and CYP2B/3A-like: EROD and testosterone 6beta-hydroxylation, respectively) were low and did not correlate with concentrations of non- or mono-ortho Cl-substituted PCBs (NO- and MO-PCBs), or with total toxic equivalent concentrations (TEQs) for dioxin-like effects of NO- and MO-PCBs. 相似文献
3.
To investigate the use of predators' stomach contents to measure the organochlorine load in free-ranging prey, the two zooplankton species Thysanoessa inermis (euphausiids) and Themisto libellula (amphipods) were collected simultaneously from the water column and from the seabird Brünnich's guillemot (Uria lomvia)'s stomach (from crop to proventriculus). The organochlorine compounds' concentrations and relative proportion of PCB-153 generally did not differ between the two sampling methods (least square mean of Sigma organochlorines=5.9 and 6.8 ng g(-1) wet weight for water column and stomach-sampled prey, respectively), indicating that the organochlorines in stomach-sampled prey were not yet affected by mechanical, chemical and bacterial degradation. Although the sample size is restricted, similar organochlorine concentrations and pattern in free-ranging and stomach-sampled prey may suggest that Brünnich's guillemots feed randomly on the zooplankton population rather than at more (or less) contaminated individuals. Alternatively or in addition, the similar concentrations and pattern suggest that the contaminant levels in Barents Sea zooplankton do not influence their behaviour to change the vulnerability to predation. In conclusion, the organochlorine concentrations and pattern in zooplankton collected from seabirds' stomach correspond with levels in free-ranging prey. 相似文献
4.
Within a family there are conflicts of interest between parents and offspring, and between male and female parents, over the
supply of parental care. The observed pattern of parental care is the outcome of negotiations within the family, and may be
influenced by environmental factors such as food abundance. We experimentally increased food supply to ten Tengmalm’s owl
(Aegolius funereus) nests from hatching to fledging, mimicking natural cached prey. Ten un-supplemented nests served as controls. Parents and
offspring were fitted with radio-tags. Food provisioning by parents was measured both in the (1) mid- and (2) late nestling
stage and in the (3) early and (4) late post-fledging stage. In response to food supplementation, both males and females reduced
food provisioning, but the effect was more pronounced in females. Females generally contributed much less to food provisioning
than males, and food supplementation increased the difference between the sexes. Mass loss during the brooding stage was substantially
lower for supplemented than for control females. Food supplementation did not improve offspring survival, and had no effect
on body measurements of nestlings. In conclusion, parents of both sexes used the increased food supply to reduce the costs
of caring for their current offspring, but females responded more strongly than males. 相似文献
5.
The photosynthetic functionality in chloroplasts in the two sacoglossan molluscs Placida dendritica and Elysia viridis from the Trondheim fjord in Norway was studied. P. dendritica and E. viridis with no functional chloroplasts in their digestive system were introduced to the green macroalgae Codium fragile. Our results showed that P. dendritica was not able to retain functional (photosynthetic) chloroplasts. Transmission electron microscopy (TEM) showed that chloroplasts
were directly digested when phagocytosed into the digestive cells. Four stages of chloroplast degradation were observed. A
corresponding operational quantum yield of chl a fluorescence (ΦPSII ~ 0) indicated autofluorescence, and the presence of highly degraded chl a supported these observations. In contrast, E. viridis was able to retain functional chloroplasts. For this species it took only 1 week for the chloroplasts inside the digestive
cells to acquire the same ΦPSII and light utilisation coefficient (α) as C. fragile kept under the same light conditions. Data for 8 days showed a 2–6-fold increase in the maximum photosynthetic rate (P
max) and light saturation index (E
k) relative to C. fragile. This increase in available light was probably caused by a reduced package effect in the digestive gland of E. viridis relative to C. fragile, resulting in a partial photoacclimation response by reducing the turnover time of electrons (τ). Isolated pigments from C. fragile compared to E. viridis showed the same levels of photosynthetic pigments (chl a and b, neoxanthin, violaxanthin, siphonaxanthin, siphonein and β,ε-carotene) relative to μg chl a (w:w), indicating that the chloroplasts in E. viridis did not synthesise any new pigments. After 73 days of starvation, it was estimated that chloroplasts in E. viridis were able to stay photosynthetic 5–9 months relative to the size of the slugs, corresponding to an RFC of level 8 (a retention
ability to retain functional chloroplasts (RFC) for more than 3 months). The reduction in ΦPSII, P
max and α as a function of time was caused by a reduction in chloroplast health and number (chloroplast thylakoid membranes and
PSII are degraded). These observations therefore conclude that chloroplasts from C. fragile cannot divide or synthesise new pigments when retained by E. viridis, but are able to partially photoacclimate by decreasing τ as a response to more light. This study also points to the importance
of siphonaxanthin and siphonein as chemotaxonomic markers for the identification of algal sources of functional chloroplasts. 相似文献
6.
Geir Rudolfsen Rudolf Müller Davnah Urbach Claus Wedekind 《Behavioral ecology and sociobiology》2008,62(4):561-567
The mating behavior and reproductive strategies of Alpine whitefish like Coregonus zugensis (Nüsslin) are poorly understood, probably because they spawn in deep water where direct observations are difficult. In this
study, we interpret life-history and sperm quality traits of fish that we caught from their spawning place. We found that
males invest heavily into gonadal tissue (up to 5.6% of their body weight), which is, in comparison to other fish, consistent
with external fertilization, distinct pairing and moderate to high communal spawning, or no pairing and low to moderate communal
spawning. Sperm competition theory and recent experimental studies on other salmonids predict that males optimize ejaculate
characteristics in relation to the costs of sperm and the level of competition they have to expect: dominant males are predicted
to invest less into ejaculate quality and to have slower spermatozoa than subdominant males. We found that spermatozoa of
older males are slower than those of younger males. Moreover, older males have larger breeding tubercles, a secondary sexual
trait that has, in some previous studies, been found to be linked to good condition and to good genetic quality. Our results
suggest that C. zugensis has age-linked reproductive strategies, that multimale spawning is common, i.e., that sperm competition plays a significant
role, and that older males are on average dominant over younger males at the spawning place. 相似文献
7.
Spatial anatomy of species survival: effects of predation and climate-driven environmental variability 总被引:1,自引:0,他引:1
Ciannelli L Dingsør GE Bogstad B Ottersen G Chan KS Gjøsaeter H Stiansen JE Stenseth NC 《Ecology》2007,88(3):635-646
The majority of survival analyses focus on temporal scales. Consequently, there is a limited understanding of how species survival varies over space and, ultimately, how spatial variability in the environment affects the temporal dynamics of species abundance. Using data from the Barents Sea, we study the spatiotemporal variability of the juvenile Atlantic cod (Gadus morhua) survival. We develop an index of spatial survival based on changes of juvenile cod distribution through their first winter of life (from age-0 to age-1) and study its variability in relation to biotic and abiotic factors. Over the 25 years analyzed (1980-2004), we found that, once the effect of passive drift due to dominant currents is accounted for, the area where age-0 cod survival was lowest coincided with the area of highest abundance of older cod. Within this critical region, the survival of age-0 cod was negatively affected by its own abundance, by that of older cod, and by bottom depth. Furthermore, during cold years, age-0 cod survival increased in the eastern and coldest portion of the examined area, which was typically avoided by older conspecifics. Based on these results we propose that within the examined area top-down mechanisms and predation-driven density dependence can strongly affect the spatial pattern of age-0 cod survival. Climate-related variables can also influence the spatial survival of age-0 cod by affecting their distribution and that of their predators. Results from these and similar studies, focusing on the spatial variability of survival rates, can be used to characterize species habitat quality of marine renewable resources. 相似文献
8.
Heli Routti Bert van Bavel Robert J. Letcher Augustine Arukwe Shaogang Chu Geir W. Gabrielsen 《Environmental pollution (Barking, Essex : 1987)》2009,157(8-9):2428-2434
The present study investigates the concentrations and patterns of organochlorine pesticides (OCPs) and their metabolites in liver and plasma of two ringed seal populations (Phoca hispida): lower contaminated Svalbard population and more contaminated Baltic Sea population. Among OCPs, p,p′-DDE and sum-chlordanes were the highest in concentration. With increasing hepatic contaminant concentrations and activities of xenobiotic-metabolizing enzymes, the concentrations of 3-methylsulfonyl-p,p′-DDE and the concentration ratios of pentachlorophenol/hexachlorobenzene increased, and the toxaphene pattern shifted more towards persistent Parlar-26 and -50 and less towards more biodegradable Parlar-44. Relative concentrations of the chlordane metabolites, oxychlordane and -heptachlorepoxide, to sum-chlordanes were higher in the seals from Svalbard compared to the seals from the Baltic, while the trend was opposite for cis- and trans-nonachlor. The observed differences in the OCP patterns in the seals from the two populations are probably related to the catalytic activity of xenobiotic-metabolizing enzymes, and also to differences in dietary exposure. 相似文献
9.
Berge JA Brevik EM Bjørge A Følsvik N Gabrielsen GW Wolkers H 《Journal of environmental monitoring : JEM》2004,6(2):108-112
An increasing number of studies indicate that marine mammals and some seabirds are exposed to organotins. However, results from northern and Arctic areas are few. Here results from analysis of tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPhT), diphenyltin (DPhT) and monophenyltin (MPhT) in harbour porpoise (Phocoena phocoena), common seal (Phoca vitulina), ringed seal (Phoca hispida) and glaucous gull (Larus hyperboreus) from Norwegian territory are presented. Relatively high concentrations of DBT, TBT and MBT were observed in muscle, kidney and liver from harbour porpoises caught in northern Norway in 1988, just before restrictions on the use of tributyltin (TBT)(mainly on small boats) were introduced in several European countries. The concentrations in harbour porpoise muscle tissue were reduced significantly 11 years later, possibly as a result of the introduced restrictions. Considerably lower concentrations of butyltins were observed in the seals compared to porpoises. The lowest levels of organotins were found in ringed seals from Spitsbergen, where only traces of dibutyltin (DBT) and monobutyltin (MBT) were observed. Traces of DBT and MBT were also found in some individual glaucous gulls from Bear Island. The sum of the degradation products MBT and DBT in liver samples from all analysed species were generally higher than TBT itself. Triphenyltin (TPhT) was observed in all porpoise samples and in livers of common seals. Also the sum of the degradation products MPhT and DPhT in liver samples from porpoise and common seals were higher than TPhT. No traces of phenyltins were found in ringed seals from Spitsbergen or in glaucous gulls from Bear Island. The limited data available indicate low to moderate exposure to organotins in northern areas (Spitsbergen and Bear Island). Marine mammals are however more exposed further south along the Norwegian Coast. 相似文献
10.
McKinney MA Letcher RJ Aars J Born EW Branigan M Dietz R Evans TJ Gabrielsen GW Peacock E Sonne C 《Environment international》2011,37(2):365-374
Flame retardants and legacy contaminants were analyzed in adipose tissue from 11 circumpolar polar bear (Ursus maritimus) subpopulations in 2005-2008 spanning Alaska east to Svalbard. Although 37 polybrominated diphenyl ethers (PBDEs), total-(α)-hexabromocyclododecane (HBCD), 2 polybrominated biphenyls (PBBs), pentabromotoluene, pentabromoethylbenzene, hexabromobenzene, 1,2-bis(2,4,6-tribromophenoxy(ethane) and decabromodiphenyl ethane were screened, only 4 PBDEs, total-(α-)HBCD and BB153 were consistently found. Geometric mean ΣPBDE (4.6-78.4 ng/g lipid weight (lw)) and BB153 (2.5-81.1 ng/g lw) levels were highest in East Greenland (43.2 and 39.2 ng/g lipid weight (lw), respectively), Svalbard (44.4 and 20.9 ng/g lw) and western (38.6 and 30.1 ng/g lw) and southern Hudson Bay (78.4 and 81.1 ng/g lw). Total-(α)-HBCD levels (<0.3-41.1 ng/g lw) were lower than ΣPBDE levels in all subpopulations except in Svalbard, consistent with greater European HBCD use versus North American pentaBDE product use. ΣPCB levels were high relative to flame retardants as well as other legacy contaminants and increased from west to east (1797-10,537 ng/g lw). ΣCHL levels were highest among legacy organochlorine pesticides and relatively spatially uniform (765-3477 ng/g lw). ΣDDT levels were relatively low and spatially variable (31.5-206 ng/g lw). However, elevated proportions of p,p'-DDT to ΣDDT in Alaska and Beaufort Sea relative to other subpopulations suggested fresh inputs from vector control use in Asia and/or Africa. Comparing earlier circumpolar polar bear studies, ΣPBDE, total-(α)-HBCD, p,p'-DDE and ΣCHL levels consistently declined, whereas levels of other legacy contaminants did not. International regulations have clearly been effective in reducing levels of several legacy contaminants in polar bears relative to historical levels. However, slow or stalling declines of certain historic pollutants like PCBs and a complex mixture of "new" chemicals continue to be of concern to polar bear health and that of their arctic marine ecosystems. 相似文献