催化荧光法测定痕量亚硝酸根

本文研究了在稀磷酸介质中，亚硝酸根对溴酸钾氧化中笥红的反应，建立了催化荧光法测定痕量亚硝酸根的方法，实验表明，亚硝酸根在０．０５－０．４０μｇ．２５ｍｌ＾－１范围内与ΔＦ成线性关系，大多数常见的共存离子不影响其测定。本法用于水样中亚硝酸根的测定，结果比较满意。     

Seasonal variability of intertidal bacterial metabolism and growth efficiency in an exposed sandy beach during low tide

Benthic gross primary production (GPP) and community respiration (BCR) were regularly measured on sandy beach sediment during low tide in a megatidal ecosystem. These measurements were assessed during 2 years in situ within a benthic chamber simultaneously with bacterial production (BP). Results suggested that community respiration in Wimereux sandy beach sediments was probably dominated by bacterial respiration and that the estimated benthic bacterial growth efficiency (BGE) was highly variable. Although temperature significantly controlled both BP and BCR during low tide at the annual scale, the temperature effect on BGE was not significant. The instability and sediment erosion caused by the wave action and the tidal cycle were thus thought to influence the BGE. Since the sampling site is regularly affected by Phaeocystis foam deposit (enhancing the BCR and decreasing the BGE), and since GPP rates were highly variable and supported by high assimilation numbers (i.e., >1 mgC mgChla ⁻¹ h⁻¹), phytoplankton organic matter deposit following the immersion of the study site was thought to explain the BGE variability.     

Ontogenetic diel vertical migration of the planktonic copepod Calanus sinicus in the Inland Sea of Japan

The ontogenetic diel vertical migration of the planktonic copepod Calanus sinicus was investigated in the Inland Sea of Japan in November 1988 and March 1989, when the water temperature was weakly stratified in a reversed manner. In both investigations a pronounced ontogenetic difference in vertical distribution was found. Spawning always occurred during nighttime, being confined to the upper 40 m water column in November but to the layer below 35 m in March. The distribution of pre-feeding nauplius stages, NI and NII, was more or less similar to that of the eggs. The first-feeding NIII performed a marked upward migration, and late nauplius stages (NIV to NVI) and early copepodite stages (CI and CII) continuously aggregated in the upper water column where phytoplankton was abundant. CIII to CVI (adult female and male) tended to disperse in the whole water column. In November, however, they avoided the upper 10 m strate during daytime and some individuals migrated upward to the surface during nighttime. In March, CV and CVI aggregated in the layer between 5 and 15 m deep in the daytime and migrated both upward and downward at dusk, resulting in homogeneous distributions during the nighttime.     

Solitary nesting as an alternative breeding tactic in colonial nesting bluegill sunfish (Lepomis macrochirus)

Colonial breeding can evolve in response to benefits afforded by clumped individuals, such as reduced predation and increased ease of assessing potential mates. However, colonial breeding can also impose costs such as increased disease transmission or increased cuckoldry. Here, we investigate solitary nesting as a potential alternative breeding tactic in colonial breeding bluegill sunfish (Lepomis macrochirus). Most male bluegill, termed parentals, compete for nesting sites in colonies and then court and spawn with females and provide sole care of the eggs. Although nesting in a colony results in reduced predation and fungal infection of broods, it comes at a cost of increased parasitism by specialized cuckolder males that do not nest. We found that 4.5% of parentals forgo spawning in a colony and instead construct nests solitarily. Solitary males were of similar size and age to colonial males, but were in significantly better condition. Solitary males obtained as many eggs as males nesting in the center of colonies, and significantly more than males nesting on the periphery of colonies. Thus, females do not appear to discriminate against solitary males. Solitary males had smaller ear tabs, a presumed sexually selected character used by parental males in intrasexual competition, than colonial males. Tracking data revealed consistency in nesting tactic (but not nest position within the colony) between spawning attempts. We suggest that solitary nesting represents either a facultative decision made by parental males in top condition at the onset of breeding, or a life history decision to forgo spawning in colonies.Communicated by K. Lindström     

Distribution patterns of meiofauna associated with a sublittoral<Emphasis Type="Italic"> Laminaria</Emphasis> bed in the Cantabrian Sea (north-eastern Atlantic)

This study deals with meiofauna associated with a sublittoral population of the kelp Laminaria ochroleuca located on the northern coast of Spain. By sampling once a year over a 4-year period, we examined patterns of faunal distribution as a function of some environmental factors at the meso-scale level (depth, and exposure to waves and surge). We also examined the relationship between L. ochroleuca abundance (as dry weight biomass and number of plants per sampling quadrat) and abundance and diversity of meiofauna. Finally, we investigated patterns of within-plant distribution (algal frond vs. algal holdfast), using also the meiofauna of the adjacent bottom as a referent to estimate the level of "phytal dependence" of the meiofauna collected on L. ochroleuca. We found that the bulk of permanent meiofauna consisted of nematodes, copepods, mites, polychaetes, tanaids and ostracods, with copepods being predominant on the fronds of the alga and nematodes in the holdfasts. The temporary meiofauna consisted of juvenile amphipods, bivalves and gastropods, together with barnacle nauplii and cyprids. Abundance and major composition of meiofaunal taxa were unrelated to both depth and hydrodynamic exposure of the sampling quadrats. However, we detected significant qualitative and quantitative faunal differences as a function of microhabitat. All meiofaunal groups were more abundant in holdfast samples than in frond and bottom samples. The gross taxonomic composition of meiofauna in bottom samples was similar to that in holdfast samples, but substantially different from that of meiofauna associated with the fronds. The L. ochroleuca holdfasts, in which dense aggregations of meiofauna can occur, appear to function as ecotone between phytal and rocky-bottom microhabitats. All together, our results suggest that the distribution of meiofauna within the Laminaria bed is mostly affected by factors operating at the microhabitat level rather than the meso-scale level.Communicated by L. Hagerman, Helsingør     

Ultrastructural,biochemical, and immunological characterization of two populations of the mytilid mussel <Emphasis Type="Italic">Bathymodiolus</Emphasis><Emphasis Type="Italic">azoricus</Emphasis> from the Mid-Atlantic Ridge: evidence for a dual symbiosis

A recently described species of mytilid mussel, Bathymodiolus azoricus Von Cosel et al., 1999, was observed to be the dominant organism at the hydrothermal vents off the Azores, at both the Lucky Strike and Menez Gwen sites. Evidence suggests this species of Bathymodiolus represents yet another example of the intriguing dual symbiosis known in three other species of deep-sea mytilid mussels. Transmission electron micrographs (TEM) show the majority of gill bacteriocytes in mussels sampled from both populations to contain two distinct symbiont morphotypes. One morphotype is characterized by large size (mean diameter, 1.25 µm), coccoid shape, and stacked intracytoplasmic membranes that are consistent with the morphology of type I methanotrophs. The second morphotype is smaller (mean diameter, 0.35 µm) and was observed in coccoid or rod shapes. Immunoblots revealed the presence of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) and methanol dehydrogenase (MeDH) in both populations of mussels. Activities of these enzymes, as well as sulfate adenylyl transferase (ATP sulfurylase) and adenylyl sulfate reductase (APS reductase), were detected in gill extracts. The activities measured for the two populations were highly variable, though the population sampled from Lucky Strike showed higher RubisCO activity. Stable carbon isotope values (Lucky Strike, '¹³C=-32.6ǂ.3‰; Menez Gwen, '¹³C=-22.8ǂ.4‰) are in the range of previously reported stable carbon isotope measurements for mytilid mussels hosting a dual symbiosis. Collectively, these results provide evidence for the activity of both sulfur-oxidizing and methane-oxidizing metabolic pathways in B. azoricus. Furthermore, evidence for a greater dependence on methanotrophy in the Menez Gwen mussel population is offered by analysis of cell counts from TEMs. Higher methanotroph numbers, and putatively activity, in this population of mussels are further supported by published geochemical data indicating higher methane concentrations in the vent fluids at Menez Gwen. This finding suggests that environmental conditions may regulate a balance between the physiological activities of different symbiont populations associated with these mussels. The existence of a dual symbiosis could thus confer greater environmental tolerance and increased niche space to the mytilid host in the stochastic hydrothermal vent habitat.     

Calanoid copepod eggs in sea-bottom muds. IV. Effects of some environmental factors on the hatching of resting eggs

During cadmium uptake by the shore crab Carcinus maenas (L.), cadmium appears in both haemolymph and urine within 1 h, and comes into equilibrium with the haemolymp after some 60 h. The equilibrium concentration for haemolymph cadmium is always considerably less than that of the external medium, whether the latter is close to background level or at the artificially high concentration of 2.2 mg l^-1. Despite earlier evidence that cadmium entering the haemolymph is mainly bound to protein, current results show most of this to be freely labile and quickly displaced by cadmium taken up subsequently. There is some evidence to suggest that cadmium is passed on from the haemolymph to the hepatopancreas. A large proportion of whole-body cadmium is adsorbed onto the exoskeleton and gills. The comparatively rapid efflux of ¹⁰⁹Cd from loaded crabs over a period of 1 week is mainly due to desorption of this cadmium from the outer body surface.     

广州城市生态环境变化

对广州城市生态环境因子的大气，水，固体废弃物和噪声污染状况近十年数据结合广州城市发展，分析其环境污染变化特征，结果表明，广州市大气环境污染已由煤烟型向石油型转变;环境中有机污染严重，主要表现为氨氮，BOD5，砷化物和汞化物污染，固体垃圾产出量逐年增加，声环境在逐步好转。     

Carbon-dioxide production and metabolic parameters in the ophiurid Ophiothrix fragilis

As part of the evaluation of fluxes between the water column and a rich benthic community of the Dover Strait (Eastern English Channel), laboratory measurements of oxygen consumption were carried out on a common ophiurid, Ophiothrix fragilis (Abildgaard), from February 1993 to February 1995. The mean O₂-consumption rate was evaluated at 0.31 mg O₂ g⁻¹ h⁻¹ (ash-free dry weight). Simultaneous measurements of O₂ consumption and CO₂ production using the pH-alkalinity method revealed an average respiratory quotient of 0.69 proved suitable for converting oxygen demand to carbon flux. A seasonal trend in respiration data was demonstrated by sinusoidal curves fitted to O₂-uptake and CO₂-release data as a function of time. The influence on respiration rate of two seasonal parameters (temperature and food availability) is discussed; linear regression indicated a highly significant relationship between O₂ consumption (or CO₂ production) and temperature; both O₂-consumption and CO₂-production rates decreased with starvation. The average O:N ratio was estimated at 8.46, close to the theoretical value when proteins constitute the catabolic substrate. The annual carbon respired by the O. fragilis community examined and the estimated annual primary production by phytoplankton indicate that the respiration of the O. fragilis community could supply 35% of phytoplankton carbon requirements. Received: 1 August 1996 / Accepted: 4 September 1996     

Biodegradation of shells of the black pearl oyster,Pinctada margaritifera var. cumingii,by microborers and sponges of French Polynesia

The composition, distribution and infestation sequence of organisms that destroy the commercially valuable shells of the black oyster Pinctada margaritifera var. cumingii Jameson, 1901 were studied. Three ecologically different groups of boring (euendolithic) organisms were identified: (1) phototrophic boring microorganisms (cyanobacteria, Hyella caespitosa, Hyella sp., Mastigocoleus testarum, Plectonema terebrans, and green algae, Phaeophila dendroides, Ostreobium quekettii); (2) heterotrophic boring microorganisms (fungi, Ostracoblabe implexa); (3) filter-feeding boring organisms (sponges, Cliona margaritiferae, C. vastifica). The phototrophic endoliths dominate the external pristmatic region of the shell, whereas the valuable interior nacreous region is attacked mainly by heterotrophs. Boring patterns reflect in part the shape and behaviour of the organisms and in part the structural properties of the shell, and inflict different types of damage. Infestation starts with microbial borers, which prepare the conditions for later invasion by more damaging clionid sponges. The infestation begins always at the apex, the oldest part of the shells, from which the periostracum is often removed by natural attrition or by cleaning procedure. The rate of bioerosion in 1 yr-old hatchery shells is 36 times higher than in natural populations.