where k (M− 2 s− 1) can be determined from the
in the pH range 2 to 5, from 5 to 40 °C and 0.01 to 1 M.The effect of pH and ionic strength on the reaction suggest that the rates are due to
where H2A = H2CrO4, HA = HCrO4, H2B = H2SO3 and HB = HSO3. The overall rate expression over the investigated pH range can be determined from
k=kH2A–H2B(αH2A)(αH2B)2+kHA–H2B(αHA)(αH2B)2+kH2A–HB(αH2A)(αHB)2
with kH2A−H2B = 5.0 × 107, kHA–H2B = 1.5 × 106 and kH2A–HB = 6.7 × 107.Fe(III) in the range 1.5 to 20 μM exerts a small catalytic effect on the reaction and significantly lowers the initial concentration of Cr(VI) compared to the nominal value. Contrary to Fe(III), formaldehyde (20 to 200 μM) reacts with S(IV) to form the hydroxymethanesulfonate adduct (CH2OHSO3), which does not react with Cr(VI). Major cations Mg2+ and some minor elements such as Ba2+ and Cu2+ did not affect the rates. The application of this rate law to environmental conditions suggest that this reaction may have a role in acidic solutions (aerosols and fog droplets). This reaction becomes more important in the presence of high Fe(III) and low HMS concentrations, contributing to affect the atmospheric transport of chromium species and the distribution of redox species of chromium, which reach surface water from atmospheric depositions.  相似文献   

17.
The barnacles Chirona (Striatobalanus) amaryllis (Darwin 1854) and Megabalanus coccopoma (Darwin 1854) (Crustacea,Cirripedia): two invasive species new to tropical West African waters     
《African Journal of Marine Science》2013,35(2):265-268
The collection of the barnacle Chirona (Striatobalanus) amaryllis (Darwin 1954) (Crustacea, Cirripedia) from the hull of a ship that had been operating for five months in the Gulf of Guinea and off Sierra Leone triggered a closer investigation of the cirriped fauna of the West African coast. Both C. amaryllis and Megabalanus coccopoma can now be added to the list of successful invasions in tropical West African waters. This discovery, as well as the circumstances of the findings, necessitates an update of the invertebrate faunal inventory of tropical West African marine waters.  相似文献   

18.
Pericosmus sp. (Echinoidea: Spatangoida) recorded from northern New Zealand (note)     
D. G. McKnight 《新西兰海洋与淡水研究杂志》2013,47(4):793-794
Recently dead fragments of the spatangoid echinoid Pericosmus sp. are recorded from the northern Bay of Plenty, 288–318 m. This record adds a further genus of Indo‐Pacific echinoderms to the New Zealand fauna.  相似文献   

19.
Food habits of some deep-sea fish off South Africa's west coast and Agulhas Bank. 1. The grenadiers (Teleostei: Macrouridae)     
《African Journal of Marine Science》2013,35(2):409-425
The food habits of 10 species of grenadier collected from the upper continental slope off South Africa's west coast and Agulhas Bank are described. Three feeding strategies were identified. Members of the demersal micro- or mesocarnivore feeding guild and grazer feeding method include Caelorinchus braueri, C. simorhynchus, juvenile Coryphaenoides striaturus, Lucigadus ori, Malacocephalus laevis, Nezumia brevibarbata, N. micronychodon and N. umbracincta. A second strategy, that of Caelorinchus matamua and adult Coryphaenoides striaturus, involved switching approximately equally from demersal grazing to midwater picking or stalking. The deep-pelagic Mesobius antipodum displayed a third strategy, that of a midwater mesocarnivore picking or stalking. Ontogenetic dietary shifts were noted for the primarily demersal grazers Caelorinchus braueri, C. simorhynchus, Coryphaenoides striaturus and Malacocephalus laevis. Mesopelagic fish, shrimps and squid formed part of the diet of all species. These prey, taken at the bathyal/deep-pelagic interface, are an important source of energy transport from productive surface waters to the deep benthos.  相似文献   

20.
Etmopterus alphus n. sp.: a new lanternshark (Squaliformes: Etmopteridae) from the south-western Indian Ocean     
DA Ebert  N Straube  RW Leslie  S Weigmann 《African Journal of Marine Science》2016,38(3):329-340
A new species of lanternshark, Etmopterus alphus (Squaliformes: Etmopteridae), is described from the south-western Indian Ocean. The new species resembles other members of the ‘Etmopterus lucifer’ clade in having linear rows of dermal denticles and most closely resembles E. molleri from the south-western Pacific. The new species is fairly common along the upper continental slopes off central Mozambique, at depths between 472 and 558?m, and is also found on the southern Madagascar Ridge in 650–792?m depth. It can be distinguished from other members of the E. lucifer clade by a combination of characteristics, including arrangement of flank and caudal markings, dimension of flank markings and shape, size and arrangement of dermal denticles along the body. Molecular analysis further supports the distinction of E. alphus from other members of the E. lucifer clade.  相似文献   

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1.
The unique holotype of Arnoglossus boops Hector is compared with specimens of Arnoglossus scapha (Schneider). It is concluded that the two species are identical, and that A. boops is therefore a junior synonym of A. scapha.  相似文献   

2.
An unidentified species of the genus Moina was found in a Pasveer sewage treatment plant at Glensiide, Wellington; it is described and illustrated. A survey of the literature shows that this is probably the first published record of the genus in New Zealand (M. lemnae, previously recorded, has since been tentatively referred to the genus Pseudomoina); sewage ponds in India and South Africa have yielded M. dubia.  相似文献   

3.
4.
The whale‐louse Scutocyamus antipodensis n.sp., ectoparasitic on Hector's dolphin, Cephalorhynchus hectori (van Beneden), is described and figured from material collected in Cloudy Bay, Cook Strait, New Zealand. Morphologically the new species is very close to S. parvus Lincoln & Hurley, the type and only other species of the genus, known only from the North Sea. However, the two species differ in the detailed structure and spinosity of the body and pereopods.  相似文献   

5.
High infestations of the nematode Hedruris spinigera were found in stomachs of perch when they had been feeding on smelt Retropinna retropinna. When perch fed heavily on. smelt, 80% carried Hedruris, but when this food source was not readily available the infection declined rapidly.  相似文献   

6.
Teredicola typicus, previously recorded from Bankia australis Caiman, 1920 at two sites in the Auckland area, has been found at Bay of Islands, Whangarei, Mahurangi, and Coromandel Harbours in the North Island of New Zealand. Two specimens have also been found in another shipworm, Lyrodus pedicellatus (Quatrefages, 1849) at Coromandel, a first record from this host in New Zealand.  相似文献   

7.
The small-scale distribution characteristics of three species of the anomuran genus Munida, namely Munida rutllanti, Munida intermedia and Munida tenuimana, have been studied on the lower shelf and upper-middle continental slope near the coasts of Tarragona and the Ebro delta region in the western Mediterranean. The differential bathymetric distribution showed that a fair degree of overlap exists between M. rutllanti and M. intermedia, with the former being mainly found at shallower depths. The size population structure of the three species showed that polymodality, as indicative of a longer life-span and of a higher degree of population structuring was more evident in the deeper-living species, whereas unimodality, as an indication of a recruitment dependent population, was more evident in the shallowest-occurring species. Geostatistics have been applied to determine the degree of spatial variability occurring in M. intermedia abundance, the better-sampled species. The Mantel test has been used to assess the significance of the overlap between the three species distributions as well as the relation between certain population parameters. A discussion on the population characteristics of M. rutllanti is made in relation with its expansion along the western Mediterranean in the last decades.  相似文献   

8.
Cold seeps have recently been discovered in the Nile deep‐sea fan (Eastern Mediterranean), and data regarding associated fauna are still scarce. In this study, two bivalve species associated with carbonate crusts and reduced sediment are identified based on sequence analysis of their 18S and 28S rRNA‐encoding genes, and associated bacterial symbioses are investigated using 16S rRNA gene sequencing and microscopy‐based approaches. The specimens are closely related to Myrtea spinifera and Thyasira flexuosa, two species previously documented at various depths from other regions but not yet reported from the Eastern Mediterranean. Both species harbour abundant gammaproteobacterial endosymbionts in specialized gill epithelial cells. The Myrtea‐associated bacterium is closely related to lucinid symbionts from both deep‐sea and coastal species, whereas the Thyasira‐associated bacterium is closely related to the symbiont of a T. flexuosa from coastal waters off the U.K. An epsilonproteobacterial sequence has also been identified in Thyasira which could correspond to a helicoid‐shaped morphotype observed by electron microscopy, but this was not confirmed using fluorescent in situ hybridization. Virus‐like particles were observed within some symbionts in Thyasira, mostly in bacteriocytes localized close to the ciliated zone of the gill filament. Overall, results indicate that very close relatives of shallow species M. spinifera and T. flexuosa occur at cold seeps in the Eastern Mediterranean and harbour chemoautotrophic symbioses similar to those found in their coastal relatives.  相似文献   

9.
Fecundity in Jasus verreauxi (H. Milne Edwards, 1851) has been studied by a detailed investigation of (a) the total weight of eggs carried by female specimens, (b) the average number of eggs per 1 g sample, and (c) the total number of eggs carried by females. In mid October 1966, 217 females “in berry” (that is, carrying external eggs) were examined and measured at Spirits Bay, New Zealand. The fecundity study is based on the results obtained from 21 selected specimens, with carapace lengths from 15.5 cm to 23.5 cm.

A direct relation was found between the total weight of eggs carried and increase in carapace length. The total weight of eggs carried varied from about 51 g to 238 g for carapace lengths of 15.5 cm to 23.5 cm. No correlation was shown between the average number of eggs per 1 g sample and increase in carapace length. Considerable variation was noted in the number of eggs per 1 g sample, which ranged from a low count of 6,453 eggs to a high count of 8,341 eggs. The total number of eggs carried by female J. verreauxi was found to be related to an increase in carapace length. Furthermore, increase in fecundity per relative carapace length increase was noted to be greater in smaller specimens than in larger specimens. The total number of eggs carried ranged from about 385,000 for a carapace length of 15.5 cm to 1,940,000 for a carapace length of 23.5 cm.

Fecundity, as measured by the total weight of eggs carried and the total number of eggs produced, was found to be much higher in J. verreauxi than in several Jasus species previously studied by other workers.  相似文献   

10.
Samples were collected during one annual cycle (April 2007–March 2008) at Alfacs Bay (NW Mediterranean Sea) central station in order to assess the influence of organic nutrients in the growth of the microalgae assemblage, with special reference to Pseudo-nitzschia spp. This potentially toxic diatom forms natural and recurrent blooms in the study area. To assess further the relationship between Pseudo-nitzschia spp. and nutrients an enrichment experiment with high molecular weight dissolved organic matter (HMWDOM) was performed with field samples obtained during a Pseudo-nitzschia spp. bloom. HMWDOM was extracted from water collected at Alfacs Bay. Five bioassays were prepared: N + P (seawater with addition of nitrate and phosphate), DOM (addition of HMWDOM), (−N + P) + DOM (nitrogen deficient, with addition of phosphate and HMWDOM), (N + P) + DOM (addition of nitrate, phosphate and HMWDOM), seawater control (without added nutrients), and B + DOM (control of bacteria, without microalgae). The experiment was run in batch mode over 4 days. Results from the field study revealed that the concentrations of organic nutrients mostly surpassed the inorganic pool. Pseudo-nitzschia spp. was the most frequent and abundant taxa of the microalgae community. The micro-planktonic assemblage was arranged according to a seasonal factor (ANOSIM and cluster analysis). DON, nitrate and silicate were the most important abiotic parameters contributing to the dissimilarities between seasons (SIMPER analysis) and thereby potentially influencing the seasonal distribution of microalgae in the representative station. In the experimental investigation, Pseudo-nitzschia cells increased by the end of the experiment in the DOM bioassay but no respective increase was observed for chlorophyll a. This could point to an acquisition of nutrients through the DOM fraction that would conjointly reduce the need of chlorophyll a. The data obtained suggest that organic nutrients may exert an important role in the development of microalgae, including Pseudo-nitzschia spp., in the selected location.  相似文献   

11.
The interactions of Fe(II) and Fe(III) with the inorganic anions of natural waters have been examined using the specific interaction and ion pairing models. The specific interaction model as formulated by Pitzer is used to examine the interactions of the major components (Na+, Mg2+, Ca2+, K+, Sr2+, Cl, SO4, HCO3, Br, CO32−, B(OH)4, B(OH)3 and CO2) of seawater and the ion pairing model is used to account for the strong interaction of Fe(II) and Fe(III) with major and minor ligands (Cl, SO42−, OH, HCO3, CO32− and HS) in the waters. The model can be used to estimate the activity and speciation of iron in natural waters as a function of composition (major sea salts) and ionic strength (0 to 3 M). The measured stability constants (KFeX*) of Fe(II) and Fe(III) have been used to estimate the thermodynamic constants (KFeX) and the activity coefficient of iron complexes (γFeX) with a number of inorganic ligands in NaClO4 medium at various ionic strengths: In(KFeXFeγX) = InKFeX − In(γFeX) The activity coefficients for free ions (γFe, γx) needed for this extrapolation have been estimated from the Pitzer equations. The activity coefficients of the ion pairs have been used to determine Pitzer parameters (BFeX, BFeX0, CFeXφ) for the iron complexes. These results make it possible to estimate the stability constants for the formation of Fe(II) and Fe(III) complexes over a wide range of ionic strengths and in different media. The model has been used to determine the solubility of Fe(III) in seawater as a function of pH. The results are in good agreement with the measurements of Byrne and Kester and Kuma et al. When the formation of Fe organic complexes is considered, the solubility of Fe(III) in seawater is increased by about 25%.  相似文献   

12.
A species of Moina from sewage ponds at Glenside, Wellington, New Zealand, is identifiable with Moina tenuicornis Sars, 1896, and distinguishable from Moina australiensis Sars, 1896 sensu stricto, in having rectangular sculpturing on the ephippium, ungrouped setae on the hind margin of the carapace, and in lacking a permanent supra‐ocular depression. Because of wide variation in some diagnostic characters, possibly both taxa are conspecific.

Some physical and chemical characteristics of the habitat are tabulated, since little is known of the ecological requirements of these morphologically similar species. Using mean values as a guide, the Glenside population of Moina tenuicornis favours a temperature in the vicinity of 20°c, a very slightly alkaline pH, a dissolved oxygen content in excess of 6mg/litre, a dissolved solid content of about 270 mg/litre, of which about half is organic and exerts a BOD5 of about 60 mg/litre, and suspended organic solids of about 150 mg/litre.  相似文献   

13.
Phyllosomata and nistos of Scyllarus sp. Z taken from plankton around and offshore northern New Zealand and in the Tasman Sea are presumed to be those of S. aoteanus Powell, 1949, the most common Scyllarus species in this area. The full larval and postlarval development of this species are described. Three features are characteristic of Scyllarus sp. Z phyllosomata; a dorsal crest on the cephalic shield, dorsal thoracic spines, and a forked telson in middle stages persisting as two prominent spines outreaching the telson posterior margin in the final stage. Scyllarus sp. Z's closest affinities are with a group of Scyllarus species whose phyllosomata have forked telsons in middle stages and medium to strong posterolateral telson spines in the final stage. The nisto is low in profile but distinctive in its armature. Too few Scyllarus sp. nistos have been described to suggest any group to which that of Scyllarus sp. Z can be assigned. The spatial and temporal distribution of the larvae and postlarvae of Scyllarus sp. Z are also described. Although early larval stages and postlarvae are found close to New Zealand, mid‐ and late‐stage larvae are widely distributed, some well beyond the known latitudinal range of the adults. There is probably an extended egg‐bearing and hatching period as early stage larvae are caught in most months. Variable rates of development of the larvae and/or delayed metamorphosis, are also possible.  相似文献   

14.
The impact of the scyphomedusa Aurelia sp. on planktonic assemblages was experimentally studied in enclosures incubated in situ in the sea lake of Mljet Island (Big Lake, Southern Adriatic), where jellyfish are present throughout the year. In situ feeding experiments using plankton at natural densities indicated a reduction in abundance for small calanoid and cyclopoid copepods, copepodites, nauplii and ciliates in the presence of Aurelia sp. In addition to direct predatory pressure, Aurelia sp. exerted an indirect cascading effect on autotrophic and heterotrophic microbial plankton. Phytoplankton biomass increases of up to 0.5 μg C·l?1·h?1 were mainly related to 19′‐hexanoyloxyfucoxanthin‐ and 19′‐butanoyloxyfucoxanthin‐containing phytoplankton. Bacterial production was about twice as high in the presence of Aurelia sp. and biomass was also consistently higher. It appears that the top‐down effect of predation along with material release by Aurelia sp. results in increases in microbial biomass and production.  相似文献   

15.
The hydrolysis of silicic acid, Si(OH)4, was studied in a simplified seawater medium (0.6 M Na(Cl)) at 25°C. The measurements were performed as potentiometric titrations (hydrogen electrode) in which OH was generated coulometrically. The total concentration of Si(OH)4, B, and log[H+] were varied within the limits 0.00075 B 0.008 M and 2.5 -log[H+] 11.7, respectively. Within these ranges the formation of SiO(OH)3 and SiO2(OH)22− with formation constants log β−11(Si(OH)4 SiO(OH)3 + H+) = −9.472 ±0.002 and log β−21(Si(OH)4 SiO2(OH)22− + 2H+) = −22.07 ± 0.01 was established. With B > 0.003 M polysilicate complexes are formed, however, with -log[H+] 10.7 their formation does not significantly affect the evaluated formation constants. Data were analyzed with the least squares computer program LETAGROPVRID.  相似文献   

16.
The rates of the reduction of Cr(VI) with S(IV) were measured in deaerated NaCl solution as a function of pH, temperature and ionic strength. The rates of the reaction were found to be first order with respect to Cr(VI) and second order with respect to S(IV), in agreement with previous results obtained at concentrations two order higher than the present study. The reaction also showed a first-order dependence of the rates on the concentration of the proton and a small influence of temperature with an apparent energy of activation ΔHapp of 22.8 ± 3.4 kJ/mol. The rates were independent of ionic strength from 0.01 to 1 M. The rate of Cr(VI) reduction is described by the general expression
−d[Cr(VI)]/dt=k[Cr(VI)][S(IV)]2
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