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1.
The sea urchin Lytechinus variegatus is capable of surviving chronic exposure to sodium phosphate (inorganic phosphate) concentrations as high as 3.2 mg l−1, and triethyl phosphate (organic phosphate) concentrations of 1,000 mg l−1. However, chronic exposure to low (0.8 mg l−1 inorganic and 10 mg l−1 organic phosphate), medium (1.6 mg l−1 inorganic and 100 mg l−1 organic phosphate) or high (3.2 mg l−1 inorganic and 1,000 mg l−1 organic phosphate) sublethal concentrations of these phosphates inhibits feeding, fecal production, nutrient absorption and
allocation, growth and righting behavior. Food consumption and fecal production declined significantly in individuals exposed
to medium and high concentrations of inorganic phosphates and all levels of organic phosphates. Feeding absorption efficiencies
for total organics and carbohydrates decreased significantly in individuals held in the highest concentration of organic phosphate.
Feeding absorption efficiencies for lipids were significantly reduced in the highest inorganic phosphate concentration only,
while they decreased significantly for protein with increasing phosphate exposure. Carbohydrate and lipid levels in gonad
and gut tissues decreased significantly with exposure to increasing phosphate concentrations, potentially impairing both gametogenesis
and nutrient storage in the gut. Moreover, gonad indices significantly decreased in individuals exposed to the highest concentrations
of either phosphate. Growth rates decreased significantly under the influence of all phosphate concentrations, while increasing
in seawater alone. Individuals exposed to increasing phosphate concentrations showed reduced righting responses (a measure
of stress) and no acclimation in righting times during chronic exposure to phosphates over a 4 week period. These findings
indicate that shallow-water populations of L. variegatus subjected to inorganic and organic phosphate pollutants will exhibit stress and be inhibited in their growth and performance
due to reductions in feeding, nutrient absorption and allocation of nutrients to key somatic and reproductive tissues.
Received: 10 April 2000 / Accepted: 2 October 2000 相似文献
2.
Andrew McMinn Andrew Pankowskii Chris Ashworth Ranjeet Bhagooli Peter Ralph Ken Ryan 《Marine Biology》2010,157(6):1345-1356
Primary production at Antarctic coastal sites is contributed from sea ice algae, phytoplankton and benthic algae. Oxygen microelectrodes
were used to estimate sea ice and benthic primary production at several sites around Casey, a coastal area in eastern Antarctica.
Maximum oxygen export from sea ice was 0.95 mmol O2 m−2 h−1 (~11.7 mg C m−2 h−1) while from the sediment it was 6.08 mmol O2 m−2 h−1 (~70.8 mg C m−2 h−1). When the ice was present O2 export from the benthos was either low or negative. Sea ice algae assimilation rates were up to 3.77 mg C (mg Chl-a)−1 h−1 while those from the benthos were up to 1.53 mg C (mg Chl-a)−1 h−1. The contribution of the major components of primary productivity was assessed using fluorometric techniques. When the ice
was present approximately 55–65% of total daily primary production occurred in the sea ice with the remainder unequally partitioned
between the sediment and the water column. When the ice was absent, the benthos contributed nearly 90% of the primary production. 相似文献
3.
S. Rajagopal V. P. Venugopalan G. Van der Velde H. A. Jenner 《Chemistry and Ecology》2013,29(2):119-132
Brachidontes variabilis is a common fouling mussel species in cooling water systems of tropical coastal power stations. However, there are hardly any data available on the response of B. variabilis to chlorine, a commonly used antifouling biocide. Therefore, lethal and sublethal responses of this mussel to chlorine are of considerable interest to the industry. The response of mussels in terms of mortality pattern (LT50 and LT100) and physiological activities (oxygen consumption, filtration rate, foot activity and byssus thread production) in different size groups (with shell lengths of 7–24 mm) of B. variabilis was studied in the laboratory under different chlorine concentrations (0.25, 0.50, 0.75 and 1.00 mg l?1 for sublethal responses and 1, 2, 3 and 5 mg l?1 for mortality). The results showed that the exposure time for 100% mortality of mussels decreased significantly with increasing chlorine concentration. However, mussel size was not a determinant of its chlorine tolerance: all size groups tested (with shell lengths of 7–24 mm) took comparable exposure times to reach 100% mortality at a given chlorine concentration (1–5 mg l?1). All size groups of B. variabilis showed a progressive reduction in physiological activities such as oxygen consumption, filtration rate, foot activity and byssus thread production, when chlorine residuals were increased from 0 to 1 mg l?1. The data generated in the present work are compared with similar data available for other tropical fouling mussel species to see how far relative chlorine toxicity could have influenced the relative distribution of the mussels inside the seawater intake tunnel of a power station at Kalpakkam in India. It is shown that in this insufficiently chlorinated system, the relative distribution of Brachidontes striatulus, B. variabilis and Modiolus philippinarum reflects the relative tolerance of the species to chlorine. 相似文献
4.
The effects of chronic copper exposure on growth and physiological responses of the green mussel Perna viridis were investigated by exposing the mussels to 50 μg l−1 Cu for 3 mo at 17 and 25 °C. These temperatures represent, respectively, the winter and summer seawater temperatures in Hong
Kong. Differences in the level of response between mussels exposed for 3 mo to 50 μg Cu l−1 generally increased with duration of exposure. The tissue concentration of copper had increased by 280 and 450% after 3 mo
exposure at 17 and 25 °C, and growth performances were reduced, with the 25 °C sets suffering from larger negative impact
of copper in most responses. The inhibitory effects of copper on production of the various body components generally followed
the order linear shell growth (greatest) > tissue production > byssus production > shell production. There were also decreases
in the condition index (43 and 35% reductions at 17 and 25 °C), clearance rates (10.3 and 18.5%), faeces production (11 and
16.3%), assimilation efficiency (6.8 and 9.2%) and oxygen consumption rate (12.8 and 24.8%). In contrast, the organic content
of the faeces (9.2 and 13.2% increases at 17 and 25 °C) and rate of ammonia excretion (21 and 28.6%), increased upon chronic
copper exposure. Many of the responses (e.g. changes in tissue copper content, body dry wt, shell organic content, clearance
rate and oxygen consumption rate) exhibited fluctuating levels of impact during prolonged copper exposure, while others (e.g.
faecal production rate, assimilation efficiency, tissue organic content) demonstrated steady decreasing trends with increasing
exposure time.
Received: 17 September 1999 相似文献
5.
Use of the fluorochrome calcein as an in situ growth marker in the brown mussel Perna perna 总被引:2,自引:0,他引:2
This study assesses the potential of the fluorochrome calcein for use as a growth marker in bivalve shell growth studies.
Calcein solutions were administered in situ to the brown mussel Perna perna (Linneaus), both by injection and immersion, and the effect of calcein concentrations on fluorescent mark deposition and mussel
mortality was investigated in the laboratory. Field investigations showed that, 1 month after administration, calcein injection
(125 mg l−l) into the mantle cavity produced superior results to the immersion treatments (150 and 500 mg l−l). Both methods resulted in fluorescent mark incorporation at the growing edge, but during immersion general calcein deposition
associated with endolith activity resulted in fluorescence that made identification of a distinct datum point difficult. In
contrast, the injection method produced clearly defined growth marks, which were easily distinguished from autofluorescence
and persisted without visible degradation for a minimum of 9 months. Shell growth rates estimated using the fluorescent mark
as a datum point were similar to those from earlier studies using different methods. Laboratory investigations revealed that
at␣calcein concentrations of 80 mg l−l and above, 100% of juvenile (20 to 30 mm) and adult mussels (60 to 70 mm) retained a visible growth mark, while at concentrations
>160 mg l−l all marks were bright and clearly defined. No mussel mortality was exhibited at any time, even at calcein concentrations
of 640 mg l−l, eight times higher than those required for mark deposition. These results suggest that, compared to traditional methods
of bivalve growth determination, the use of fluorochromes presents a relatively inexpensive, non-invasive and rapid alternative.
When using calcein as a growth marker, problems associated with some other fluorochromes (e.g. inconsistent mark incorporation,
high post-treatment mortality) were not exhibited.
Received: 14 July 1998 / Accepted: 23 October 1998 相似文献
6.
The annual population dynamics (nauplii, old copepodites CIV–CV and adults) and seasonal variations in reproductive parameters
of the cyclopoid copepod Oithona similis were investigated on the basis of the data 1999–2006 in Kola Bay, a large subarctic fjord in the Barents Sea. Population
density of O. similis ranged from 110 to 9,630 ind m−3 and averaged 1,020 ± 336 ind m−3. The relative abundance of adults was high during winter (~60%). At the end of winter (mid-March), the population included
a large percentage of later-stage copepodites (stage CIV 23% and stage CV 57%). There were two periods of mass spawning, in
late June and September. Autumn and summer generations strongly differed in abundance, average prosome length (PL), clutch
size (CS), egg diameter (D), egg production rates (EPR and SEPR) and female secondary production. Average PL decreased with increasing water temperature,
while D and CS were strongly correlated with PL but unaffected by temperature. Annual average EPR and SEPR were 0.55 ± 0.18 eggs female−1 day−1 and 0.0011 ± 0.003 day−1, respectively. Female secondary production averaged 0.8 ± 0.3 μg C m−3 day−1 (range 0.001–3.58). There were positive relationships between abundance, EPR, SEPR, production and water temperatures. Reproductive
parameters appeared to be controlled by hydrological factors and food conditions. 相似文献
7.
M. Peharda C. A. Richardson I. Mladineo S. Šestanović Z. Popović J. Bolotin N. Vrgoč 《Marine Biology》2007,151(2):629-638
Age, growth and population structure of Modiolus barbatus from Mali Ston Bay, Croatia were determined using modal size (age) classes in length frequency distributions, annual pallial
line scars on the inner shell surface, internal annual growth lines in shell sections of the middle nacreous layer and Calcein
marked and transplanted mussels. The length frequency distributions indicated that M. barbatus attain a length of ∼40 mm in 5–6 years indicating that a large proportion of the population in Mali Ston Bay is <5 years
old. Some mussels of ∼60 mm were predicted to be 14 years old using the Von Bertalanffy growth (VBG) equation. Up to the first
6 pallial line scars were visible in young (<6 years) mussels but in older shells the first scars became obscured by nacre
deposition as the mussel increased in length and age. The age of the older shells (>6 years) was determined from the middle
nacreous lines in shell section, which formed annually in winter between February and March; the wider dark increments forming
during summer (June to September). The oldest mussel, determined from the middle nacreous lines, was >12 years, with the majority
of mussels aged between 3 and 6 years of age. The ages of mussels ascertained using the growth lines were not dissimilar to
the ages predicted from the length frequency distributions. Age at length curves produced using modal size class data were
not different from the data obtained using the pallial scar rings and internal growth lines. Taken together these data suggest
that M. barbatus attains a length of 40 and 50 mm within 5 and 8 years, respectively. Eighty one percent of individual M. barbatus injected with a Calcein seawater solution (300 mg Calcein l−1), into their mantle cavity successfully deposited a fluorescent line, which was visible in suitably prepared shell sections
under ultra violet light. Incorporation of Calcein into the mussel shells was seasonally variable with the lowest frequency
of incorporation in mussels marked in February and recovered in May. Seasonal shell growth was observed with significantly
higher growth rates in mussels marked in May and removed in August (ANCOVA, F
3,149 = 23.11, P < 0.001). Mussels (∼18 to 22 mm) marked in May and recovered in August displayed maximal growth rates of >2.5 mm month−1 compared with a mean mussel growth rate of 1.2 ± 0.6 mm month−1. At other times of the year mussel shell growth ranged from immeasurable to 1.48 mm month−1. 相似文献
8.
Ravi Naidu Euan Smith S. M. Imamul Huq Gary Owens 《Environmental geochemistry and health》2009,31(Z1):61-68
The bioavailability of arsenic (As) in the soil environment is largely governed by its adsorption–desorption reactions with
soil constituents. We have investigated the sorption–desorption behaviour of As in four typical Bangladeshi soils subjected
to irrigation with As-contaminated groundwater. The total As content of soils (160 samples) from the Laksham district ranged
from <0.03 to approximately 43 mg kg−1. Despite the low total soil As content, the concentration of As in the pore water of soils freshly irrigated with As-contaminated
groundwater ranged from 0.01 to 0.1 mg l−1. However, when these soils were allowed to dry, the concentration of As released in the pore water decreased to undetectable
levels. Remoistening of soils to field moisture over a 10-day period resulted in a significant (up to 0.06 mg l−1) release of As in the pore water of soils containing >10 mg As kg−1 soil, indicating the potential availability of As. In soils containing <5 mg As kg−1, As was not detected in the pore water. A comparison of Bangladeshi soils with strongly weathered long-term As-contaminated
soils from Queensland, Australia showed a much greater release of As in water extracts from the Australian soils. However,
this was attributed to the much higher loading of As in these Australian soils. The correlation of pore water As with other
inorganic ions (P, S) showed a strongly significant (P < 0.001) relationship with P, although there was no significant relationship between As and other inorganic cations, such
as Fe and Mn. Batch sorption studies showed an appreciable capacity for both AsV and AsIII sorption, with AsV being retained in much greater concentrations than AsIII. 相似文献
9.
Genotypic variation in element concentrations in brown rice from Yunnan landraces in China 总被引:3,自引:0,他引:3
Yawen Zeng Hongliang Zhang Luxiang Wang Xiaoying Pu Juan Du Shuming Yang Jiafu Liu 《Environmental geochemistry and health》2010,32(3):165-177
The mineral elements present in brown rice play an important physiological role in global human health. We investigated genotypic
variation of eight of these elements (P, K, Ca, Mg, Fe, Zn, Cu, and Mn) in 11 different grades of brown rice on the basis
of the number and distance coefficients of 282 alleles for 20 simple sequence repeat (SSR) markers. Six-hundred and twenty-eight
landraces from the same field in Yunnan Province, one of the largest centers of genetic diversity of rice (Oryza sativa L.) in the world, formed our core collection. The mean concentrations (mg kg−1) of the eight elements in brown rice for these landraces were P (3,480) > K (2,540) > Mg (1,480) > Ca (157) > Zn (32.8) > Fe
(32.0) > Cu (13.6) > Mn (13.2). Mean P concentrations in brown rice were 6.56 times total soil P, so the grains are important
in tissue storage of P, but total soil K is 7.82 times mean K concentrations in brown rice. The concentrations of the eight
elements in some grades of brown rice, on the basis of the number and distance coefficients of alleles for 20 SSR markers
for the landraces, were significantly different (P < 0.05), and further understanding of the relationship between mineral elements and gene diversity is needed. There was large
variation in element concentrations in brown rice, ranging from 2,160 to 5,500 mg P kg−1, from 1,130 to 3,830 mg K kg−1, from 61.8 to 488 mg Ca kg−1, from 864 to 2,020 mg Mg kg−1, from 0.40 to 147 mg Fe kg−1, from 15.1 to 124 mg Zn kg−1, from 0.10 to 59.1 mg Cu kg−1, and from 6.7 to 26.6 mg Mn kg−1. Therefore, germplasm evaluations for Ca, Fe, and Zn concentrations in rice grains have detected up to sevenfold genotypic
differences, suggesting that selection for high levels of Ca, Fe, and Zn in breeding for mass production is a feasible approach.
Increasing the concentrations of Ca, Fe, and Zn in rice grains will help alleviate chronic Ca, Zn, and Fe deficiencies in
many areas of the world. 相似文献
10.
I. Buttino A. Ianora S. Buono V. Vitello G. Sansone A. Miralto 《Marine Biology》2009,156(6):1171-1182
Temora stylifera adult copepods were fed with four different monoalgal diets and six combinations of the same cultures for 15 days. Fecundity,
hatching success, number of cannibalized embryos, fecal pellet production, adult mortality and naupliar recruitment were compared,
in order to find the best diet for this species. Phytoplankton species tested were Prorocentrum minimum (PRO); Isochrysis galbana (ISO); Tetraselmis suecica (TETRA) and Rhodomonas baltica (RHO) which were supplied alone or in different combinations and at various concentrations ranging from a minimum of 1 mg C L−1 day−1 to a maximum of 66 mg C L−1 day−1. Of the ten diets tested, ISO was the worst and was unable to sustain egg production and adult survival possibly because
adults were unable to ingest this alga due to its small size. TETRA was also a poor food since it negatively impacted egg
production and adult survival, as well as egg hatching success, possibly due to the lack of essential compounds necessary
for optimal embryogenesis. RHO and PRO were the best foods inducing highest egg production, hatching success and naupliar
recruitment. Even if mean egg production rates were similar to those obtained with some mixed diets, carbon intake concentrations
with mixed diets were from 3 to 33 and from 6.6 to 66 times higher than with RHO and PRO given alone, respectively. Mixed
diets of ISO and PRO, especially when supplied at higher concentrations (66 mg C L−1 day−1), had a negative effect on egg hatching success and adult survival, with a corresponding reduction in naupliar recruitment.
On the other hand, mixed diets of TETRA and PRO promoted high naupliar recruitment but values were similar to PRO offered
alone. Our results indicate that a good monoalgal diet such as RHO and PRO can be as effective as a mixed diet to sustain
the mass cultivation of T. stylifera. 相似文献
11.
J. Gilmour 《Marine Biology》1999,135(3):451-462
Laboratory and field experiments were used to determine whether high (≃100 mg l−1), low (≃50 mg l−1) and control (≃0 mg l−1) levels of suspended sediment affected fertilisation, larval survival, and larval settlement in the scleractinian coral Acropora digitifera (Dana, 1846). Both high- and low-sediment treatments significantly decreased fertilisation, but post-fertilisation embryonic
development was not inhibited by suspended sediments. Larval survival and larval settlement were significantly reduced in
high- and low-sediment treatments. No difference was found between high- and low-sediment treatments in any of the three post-spawning
processes investigated, suggesting that they are susceptible to sediment concentrations which are not exceptionally high even
under natural conditions (>50 mg l−1). The introduction of an additional stress in the form of high levels of suspended sediments coupled with naturally high
variability in recruitment may have a considerable effect on the successful supply and settlement of coral larvae to a reef.
Given that many coral communities are open reproductive systems, the consequences of disturbance events are not likely to
be restricted to the impact area. Recruitment to a population may be reduced significantly in the presence of high levels
of suspended sediments because of effects on larval survival and settlement. Recruitment of larvae to adjacent populations
may also be affected due to a decreased fertilisation success and potential increases in mortality of larvae passing through
the affected site.
Received: 13 August 1998 / Accepted: 22 July 1999 相似文献
12.
Artemia franciscana was grown on Isochrysis galbana Green (clone T. Iso) at saturated food concentrations (13 to 20 mg C l−1) for 11 d at 26 to 28 °C, and 34 ppt salinity. Three groups of brine shrimp were used in the feeding experiments: metanauplius
III and IV (Group 1), post-metanauplius II and III (Group 2) and post-metanauplius VIII (Group 3), corresponding to 4-, 7-
and 11-d-old animals, respectively. The ingestion rate, clearance rate and carbon balance were estimated for these stages
at different concentrations of 14C-labeled I. galbana ranging from 0.05 to 30 mg C l−1. The handling time of algae was determined for all three groups. The ingestion rate (I, ng C ind−1 h−1) increased as a function of animal size and food concentration. In all three groups, the ingestion rate increased to a maximum
level (I
max) and remained constant at food concentrations ≥10 mg C l−1 (saturated food concentrations). The clearance rate (CR, μl ind−1 h−1) increased with increasing food concentration up to a maximum rate (CR
max), after which it decreased for even higher food concentrations. The functional response of A. franciscana was most consistent with Holling's Type 3 functional response curve (sigmoidal model), which for the two oldest groups (Group 2
and 3) differed significantly from a Type 2 response (p < 0.05). The gut passage time for the three groups of A. franciscana, feeding on saturated food concentration (20 mg C l−1), varied between 24 and 29 min. As the nauplii developed to pre-adult stage the handling time of the algae increased as a
function of animal size. The assimilation rate (ng C ind−1 h−1) in the youngest stages (Group 1 and 2) increased with increasing food concentrations, reaching a maximum level close to
10 mg C l−1. At higher food concentrations the assimilation rate decreased, and the proportions of defecated carbon increased, reaching
60 to 68% in the post-metanauplius stages (Group 3). The assimilation efficiency (%) was high at the lowest food concentrations
in all three groups (89 to 64%). At higher concentrations, the assimilation efficiency decreased, reaching 56 to 38% at the
highest concentrations.
Received: 2 February 2000 / Accepted: 25 March 2000 相似文献
13.
Effects of low dissolved oxygen on early development and swimming behaviour of veliger larvae of the scavenging gastropod
Nassarius festivus were studied. Embryonic development was significantly delayed when dissolved oxygen level was reduced to 3.0 mg O2 l−1 and no embryo hatched successfully at 0.5 mg O2 l−1. Veliger larvae hatched at 4.5 mg O2 l−1 had significantly smaller velar lobe, shell length and shell width. Median 48-h LC50 value of the veliger larvae was estimated at 1.25 mg O2 l−1 with lower swimming speed (swimming velocity and dispersal velocity) being recorded for the survivors exposed to reduced
oxygen levels. The percentage of veliger larvae that developed into crawling juveniles was significantly reduced and metamorphosis
was delayed at 4.5 mg O2 l−1 whereas all larvae at 3.5 mg O2 l−1 died before they underwent metamorphosis. Juveniles developed at 4.5 mg O2 l−1 were also smaller than those at 6.0 mg O2 l−1. Results indicated that dissolved oxygen levels well above hypoxia levels (2.8 mg O2 l−1) have already had significant impact on the hatching success and larval development in gastropods, which may lead to long-term
decreases in population growth. 相似文献
14.
Tarek G. Ammari Yasin Al-Zu’bi Samih Abu-Baker Basem Dababneh Wafa’ Gnemat Alaeddin Tahboub 《Environmental geochemistry and health》2011,33(5):427-437
Lithium is found in trace amounts in all soils. It is also found in plants and in nearly all the organs of the human body.
Low Li intake can cause behavioral defects. Thus, this study was conducted to investigate the concentration and distribution
of water-soluble Li in soils of the Jordan Valley and its concentration in citrus trees and some important food crops in view
of the significant implications of Li for human health. The concentration of soluble Li was measured in 180 soil samples collected
at two depths (0–20 and 20–40 cm) whereas its content was determined in fully expanded leaves collected from citrus and different
vegetable crops. Concentrations of soluble Li in soils vary from 0.95 to 1.04 mg l−1 in topsoil and from 1.06 to 2.68 mg l−1 in subsoil, while Li concentration in leaves ranged from 2 to 27 mg kg−1 DM. Lithium concentrations in leaves of crops of the same family or different families vary with location in the valley;
i.e., they decreased from north to south. It is concluded that soluble Li in soils and the plant family did not solely affect
Li transfer in the food chain. In addition, soil EC, Ca, Mg, and Cl, which increased from north to south, might adversely
affect plant Li uptake. The current study also showed that consuming 250–300 g FW of spinach day−1 per person is recommended to provide consumers with their daily Li requirement necessary for significant health and societal
benefits. 相似文献
15.
The diet of juvenile pink shrimp (Farfantepenaeus duorarum Burkenroad, previously Penaeus duorarum) from Long Key Bight, Florida Keys, was studied using stomach content examination, pigment measurements, and stable isotope
(δ13C and δ15N) analysis. Samples were taken over approximately 24 h on four occasions from December 1997 to June 1998. Juvenile F. duorarum fed nocturnally, the main prey being the seagrass shrimp Thor floridanus (Decapoda: Caridea: Hippolytidae), which accounted for 34% of the stomach content volume. Other common components of the
diet were bivalves (mainly Tellina sp.) with 15% volume, calcareous algae (8%), plant detritus (5%), copepods (3%), and seagrass fragments (2%). Pigment concentrations
(chlorophyll a plus phaeopigments) in F. duorarum stomachs ranged from 7 to 73 mg l−1 or 40 to 310 ng stomach−1. The exponential gastric evacuation rate was determined experimentally at 1.3 ± 0.5 h−1. Daily rations (in percent body weight) calculated from time series of stomach fullness ranged between 11 and 16% d−1. Total consumption by the population (in wet weight) ranged between 0.05 and 0.3 g m−2 d−1. Stable isotope measurements confirmed that T. floridanus was the main food source for F. duorarum. δ13C-values of whole animals of both species were identical at −10.0 ± 1.6‰ PDB. δ15N-values of both species were also not significantly different (pooled mean: 5.9 ± 1.7‰). Stomach contents of wild-caught
F. duorarum and stomach contents of F. duorarum fed T. floridanus also showed similar stable isotope values.
Received: 12 August 1999 / Accepted: 21 March 2000 相似文献
16.
Mytilus edulis L., Ruditapes philippinarum (Adams & Reeve) and Tapes decussatus L. were fed particles of the same shape (spherical), the same density (2.1 g cm−3) and the same chemical composition (SiO2), but which varied in diameter from 5 to 37 μm. Findings obtained at different particle concentrations (mean ± SD) of 51 ± 2,
105 ± 18 and 171 ± 17 mg l−1 invariably indicate that significant proportions of all particles with diameters larger than from between 7.5 and 22.5 μm
were preferentially rejected as pseudofaeces. We define the preferential ingestion index (PII) as the ratio between average
particle volume in pseudofaeces and average particle volume in food. Whatever the particle concentration or the species, this
PII was always statistically higher than 1. Irrespective of particle concentration, PII values in M. edulis were lower than in T. decussatus (averages of 1.2 and 2, respectively). PII values in M. edulis were also lower than in R. philippinarum maintained at particle concentrations above 171 ± 17 mg l−1. We suggest that preferential size-dependent rejection of larger particles could be of significant adaptive value in the
natural environment, either if there are large inorganic particles, or if the average organic content of smaller particles
is higher.
Received: 11 January 1997 / Accepted: 8 March 1997 相似文献
17.
Alžbeta Jarošová Jiří Harazim Lenka Krátká Doubravka Kolenčíková 《Environmental Chemistry Letters》2010,8(4):387-391
Phthalates are animal carcinogens and may cause death or tissue deformities. Samples of feedstuffs collected in 2005 and 2006
from industrial feed manufacturers in the Czech Republic were analysed for contamination with phthalic acid esters (PAEs),
specifically di-2-ethylhexyl phthalate (DEHP) and di-n-butyl phthalate (DBP). Samples of feed additives, premixes and raw materials were collected (year 2005, n = 26). For soybean oil, the total volume of phthalates measured (DBP + DEHP) reached a level of 131.42 mg kg−1; for rapeseed oil, fish meal and animal fats, the levels measured were 15.00, 7.96 and 58.87 mg kg−1, respectively. The lowest level of DBP + DEHP was found in corn (2.03 mg kg−1). Since phthalates were detected, samples of feed additives (n = 28) and raw materials (n = 28) were collected again in 2006. The highest levels of DBP + DEHP were found in raw materials containing fat. Phthalate
levels in rapeseed oil samples ranged from 1.38 to 32.40 mg kg−1 DBP + DEHP. For feed additives, contamination levels in vitamins and amino acids ranged from 0.06 to 3.15 and 1.76 to 4.52 mg kg−1 DBP + DEHP, respectively. Here, we show that the levels of PAEs found in cereals such as wheat, barley and corn may be regarded
as being alarmingly high, because cereals make up the largest proportion of compound feed of farm animals. 相似文献
18.
Lead (Pb) contents and partition in soils collected from eleven vegetable-growing lands in Fujian Province, China, were investigated
using a modification of the BCR (Community Bureau of Reference) sequential extraction procedure coupled with the Pb isotope
ratio technique. Pb contents in Chinese white cabbage (B. Chinensis L.) grown on the lands for this study were also measured. Results showed that Pb concentrations in fifty samples of topsoil
ranged from 456 to 21.5 mg kg−1, with each mean concentration of six sampling lands exceeding the national standard (50 mg kg−1); while Pb concentrations in edible portions of thirty-two vegetable samples ranged from 0.009 to 2.20 mg kg−1, with four sampling sites exceeding the national sanitary standard (0.2 mg kg−1). A significant correlation (r = 0.971, P < 0.01) of Pb contents in the acid-extractable fractions by BCR approach and the vegetables was observed, which indicates
that the acid-extractable Pb is useful for evaluating the metal bioavailability for plants and potential risk for human health
in soils. The determination of lead isotope ratios in different chemical forms of soils by BCR sequential extraction procedures
provides useful information on the Pb isotopic composition associated with different soil fractions (especially in the acid-extractable
fractions), and the result is helpful for the further study on controlling and reducing Pb contamination in vegetable-growing
soils. 相似文献
19.
We analysed growth of the Antarctic bryozoan Melicerita obliqua (Thornely, 1924) by x-ray photography and stable isotope analysis. M. obliqua colonies form one segment per year, thus attaining maximum length of about 200 mm within 50 years. In the Weddell and Lazarev
Seas, annual production/biomass ratio of M. obliqua is 0.1 yr−1, which is in the range of other Antarctic benthic invertebrate populations. Production amounts to 3.34 mg Corg m−2 yr−1 and 90.6 mg ash m−2 yr−1 on the shelf (100 to 600 m water depth), and to 0.13 mg Corg m−2 yr−1 and 36.8 mg ash m−2 yr−1 on the slope (600 to 1250 m water depth).
Received: 27 February 1998 / Accepted: 8 May 1998 相似文献
20.
Eva Friis Møller Christian Marc Andersen Borg Sigrún H. Jónasdóttir Suree Satapoomin Cornelia Jaspers Torkel Gissel Nielsen 《Marine Biology》2011,158(3):677-688
The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods were measured at seven stations
across the Southern Indian Ocean from productive areas off South Africa to oligotrophic waters off Northern Australia during
October/November 2006. We quantified export of copepod fecal pellet from surface waters and how much was retained. Furthermore,
the potential impact of Oncaea spp. and harpacticoid copepods on fecal pellets degradation was evaluated and found to be regional substantial. The highest
copepod abundance and fecal pellet production was found in the western nutrient-rich stations close to South Africa and the
lowest at the central oligotrophic stations. The in situ copepod fecal pellet production varied between 1 and 1,000 μg C m−3 day−1. At all stations, the retention of fecal pellets in the upper 400 m of the water column was more than 99% and the vertical
export of fecal pellets was low (<0.02 mg m−2 day−1). 相似文献