Alteration of photosystem II activity by atrazine on Chlamydomonas reinhardtii synchronized and asynchronized cell cycle cultures

Inhibition of photosystem II (PSII) activity by atrazine was investigated in the green alga Chlamydomonas reinhardtii during different states of the cell cycle. The algal cultures were maintained under continuous light or under light/dark cycle (16/8?h) to obtain homogenized cell cycle distribution. The cycle state of algal population was determined by the DNA content using flow cytometry and defined as newly divided cells before the initiation of DNA replication (G₀/G₁) and cells at the end of the replication cycle with fully duplicated DNA content (G₂/M). Under different synchronized states of the cell population, the photosynthetic activity was investigated after treatment at 10, 100, and 1000?µmol?L^?1 atrazine exposed for 24?h by using fluorescence parameters related to PSII activity measured with a plant efficiency analyzer and pulse-amplitude modulated methods. In this study, we found that the atrazine effect was different depending on cell cycle phases and the period of illumination. Algal cells under light–dark cycle showed inhibition of the PSII electron transport leading to an increase of heat energy dissipation by the PSII reaction center. Algal cells grown under continuous light was shown to be more resistant to atrazine than the cells grown under light–dark cycle.     

Feeding in dominant Antarctic copepods—does the morphology of the mandibular gnathobases relate to diet?

This study should clarify the importance of morphology and stability of the mandibular gnathobases for the diet of Antarctic copepod species. The gnathobase morphology of the dominant copepod species Calanoides acutus, Calanus propinquus, Ctenocalanus citer, Rhincalanus gigas, Metridia gerlachei, Stephos longipes, Microcalanus pygmaeus and Paraeuchaeta antarctica from the Southern Ocean was investigated in detail by means of a scanning electron microscope. The mandibular gnathobases of C. acutus, C. propinquus and C. citer have relatively short and compact teeth. These species feed mainly on diatoms and are able to crack the silicious diatom frustules with their mandibular gnathobases by directed pressure. In contrast the teeth of the mandibular gnathobases of P. antarctica are very long and pointed. The nutrition of this species consists predominantly of other smaller copepod species. The motile prey can be held by skewering, using the gnathobases, and then eventually minced. The mandibular gnathobases of P. antarctica have notably more small bristles than those of the other investigated copepod species. These bristles are probably associated with receptors and could serve to locate the prey. The morphology of the gnathobases of R. gigas and M. gerlachei is between that of P. antarctica on the one side and that of C. acutus, C. propinquus and C. citer on the other. Based on the morphology of its gnathobases the copepod species S. longipes, which has to date been found to feed primarily on phytoplankton, mainly ice algae, must also be considered a zooplankton feeder. The investigation showed that M. pygmaeus has gnathobases with surprisingly long and pointed teeth, indicating that this species very probably feeds both on phyto- and on zooplankton organisms. While the mandibular gnathobases of the males of C. propinquus, R. gigas, M. gerlachei and S. longipes have the same morphology as the females of the respective species, in the other four investigated copepod species the males have reduced (C. acutus, C. citer and M. pygmaeus) or completely missing mandibular gnathobases (P. antarctica). The teeth of the gnathobases of all studied species with the exception of M. gerlachei consist of a different material than the remaining parts of the gnathobases. This material seems to be silicate, which probably enhances the stability of the gnathobase teeth.Communicated by O. Kinne, Oldendorf/Luhe     

Comparisons between the diets of four abundant species of elasmobranchs in a subtropical embayment: implications for resource partitioning

The diets of one ray species (Rhinobatus typus) and three shark species (Carcharhinus cautus, Negaprion acutidens, Rhizoprionodon acutus) undergo size-related changes and differ among these species in the nearshore waters of a large subtropical embayment (Shark Bay) in which these elasmobranchs are abundant, thereby reducing the potential for competition for food within and among these four species. R. typus fed almost exclusively on penaeid prawns and portunid crabs, which is reflected in its narrow dietary breadth, whereas different species of teleosts constituted a major component of the diets of each size class of the three shark species. The prey consumed by the three shark species was diverse, with representatives of 15 teleost families being consumed by C. cautus and substantial volumes of cephalopods being ingested by that species and R. acutus. The pronounced differences in the diet of the single ray species and three shark species reflect differences between a bottom-dwelling and more pelagic life, and between modes of feeding and relative mouth sizes. The relative contributions of the different species of teleost to the diets of the three shark species varied. Thus, although each of these species fed on atherinids, labrids and sillaginids, C. cautus also consumed substantial amounts of platycephalids and terapontids and R. acutus and N. acutidens also ingested considerable amounts of clupeids. Furthermore, R. acutus, which is the only one of the four species that typically occurs over seagrass, was the only species that fed on the centropomid Psammoperca waigensis, which is very abundant in seagrass meadows. However, the sparid Rhabdosargus sarba, which lives in unvegetated areas, was never ingested by R. acutus, but was consumed by C. cautus and N. acutidens. As the individuals of R. typus increased in size, they progressively consumed proportionately smaller volumes of the penaeid prawns Penaeus merguiensis and Melicertus latisulcatus and relatively greater volumes of the portunid crab Portunus pelagicus, which is slightly larger and has a harder exoskeleton. In addition to teleosts, large C. cautus ingested substantial volumes of portunid crabs and ophidian reptiles, presumably sea snakes, while large N. acutidens also fed on the ray R. typus.Communicated by G.F. Humphrey, Sydney     

异噻唑啉酮类杀菌剂对黑斑蛙胚胎和蝌蚪的急性毒性

异噻唑啉酮类杀菌剂1,2-苯并异噻唑-3-酮（BIT）和甲基异噻唑啉酮（MIT）虽已在多种行业中广泛使用,但目前有关其毒性尤其对水体中生物毒性的数据还较少。鉴于BIT和 MIT在水体中普遍存在,本文研究了这两种污染物对两栖动物黑斑蛙胚胎和蝌蚪的急性毒性。黑斑蛙胚胎和蝌蚪分别暴露系列浓度的BIT和 MIT,观察化学品对其生长、发育和运动的影响,计算96小时半数致死浓度（96 h-LC₅₀）和96小时半数致畸浓度（96 h-TC₅₀）,确定最小生长抑制浓度（MCIG）。结果发现,BIT对黑斑蛙胚胎的96 h-LC₅₀和96 h-TC₅₀分别为2.99 mg?L^-1和0.60 mg?L^-1,MCIG小于0.40 mg?L^-1,对蝌蚪的96 h-LC₅₀为6.44 mg?L^-1。MIT对黑斑蛙胚胎的96 h-LC₅₀和96 h-TC₅₀分别为5.30 mg?L^-1和2.36 mg?L^-1,MCIG为2.59 mg?L^-1,对蝌蚪的96 h-LC₅₀为7.58 mg?L^-1。根据《化学农药环境安全评价准则报批稿》中两栖动物蝌蚪急性毒性的分级标准,判定BIT和MIT的毒性等级为中等。该毒性数据为异噻唑啉酮类杀菌剂的环境管理提供参考。     

异噻唑啉酮类杀菌剂对黑斑蛙胚胎和蝌蚪的急性毒性

异噻唑啉酮类杀菌剂1,2-苯并异噻唑-3-酮（BIT）和甲基异噻唑啉酮（MIT）虽已在多种行业中广泛使用,但目前有关其毒性尤其对水体中生物毒性的数据还较少。鉴于BIT和 MIT在水体中普遍存在,本文研究了这两种污染物对两栖动物黑斑蛙胚胎和蝌蚪的急性毒性。黑斑蛙胚胎和蝌蚪分别暴露系列浓度的BIT和 MIT,观察化学品对其生长、发育和运动的影响,计算96小时半数致死浓度（96 h-LC₅₀）和96小时半数致畸浓度（96 h-TC₅₀）,确定最小生长抑制浓度（MCIG）。结果发现,BIT对黑斑蛙胚胎的96 h-LC₅₀和96 h-TC₅₀分别为2.99 mg?L^-1和0.60 mg?L^-1,MCIG小于0.40 mg?L^-1,对蝌蚪的96 h-LC₅₀为6.44 mg?L^-1。MIT对黑斑蛙胚胎的96 h-LC₅₀和96 h-TC₅₀分别为5.30 mg?L^-1和2.36 mg?L^-1,MCIG为2.59 mg?L^-1,对蝌蚪的96 h-LC₅₀为7.58 mg?L^-1。根据《化学农药环境安全评价准则报批稿》中两栖动物蝌蚪急性毒性的分级标准,判定BIT和MIT的毒性等级为中等。该毒性数据为异噻唑啉酮类杀菌剂的环境管理提供参考。     

敌草快对藻类和溞类的急性毒性及其水中含量测定

敌草快是一种非选择性、广谱的联吡啶类触杀性除草剂,主要通过干扰植物细胞膜、破坏光合作用而快速发挥效果。为探究敌草快对水生生物的毒性,测定了该化合物对羊角月芽藻和大型溞的急性毒性,并建立了高效液相色谱法测定水中敌草快含量的方法。结果表明:检测方法在1.00×10-2~3.00×10-2mg a.i.·L-1范围内的线性相关系数为0.99995,添加回收率在90.3%~109%之间,相对标准偏差(RSD)为1.10%~10.3%,保留时间在7.2 min左右。按实测浓度和理论浓度分别计算敌草快对羊角月芽藻的72 h的半数效应浓度EyC50(72 h-EyC50),分别为3.16×10-2mg a.i.·L-1和3.32×10-2mg a.i.·L-1,均为高毒;对大型溞48 h的半数效应浓度EC50(48 h-EC50)分别为1.18×10-2mg a.i.·L-1和1.33×10-2mg a.i.·L-1,均为剧毒。     

狼尾草根系对阿特拉津长期胁迫的氧化应激响应

通过盆栽实验研究了抗性植物狼尾草根部丙二醛(MDA)、脯氨酸(Pro)、抗坏血酸(As A)含量及超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)等氧化应激生理指标对不同浓度阿特拉津长期(48 d)胁迫的响应规律。结果表明:当阿特拉津胁迫浓度分别高于20 mg·kg~(-1)和50 mg·kg~(-1)时,狼尾草根系的MDA与Pro含量较对照组显著升高(P0.05);随着阿特拉津胁迫浓度的增加,狼尾草根部SOD和GR活性呈先升高后降低的趋势,其中当阿特拉津胁迫浓度为20 mg·kg~(-1)时,SOD和GR活性达到最大值;供试植物根系中As A含量与阿特拉津胁迫浓度呈正相关。综上,中低浓度(≤20 mg·kg~(-1))阿特拉津处理没有对狼尾草的根系产生明显的氧化胁迫效应,狼尾草根系的上述抗氧化应激生理指标对于发挥阿特拉津抗性起着重要的作用。     

Negligible evidence for regional genetic population structure for two shark species <Emphasis Type="Italic">Rhizoprionodon acutus</Emphasis> (Rüppell, 1837) and <Emphasis Type="Italic">Sphyrna lewini</Emphasis> (Griffith &; Smith, 1834) with contrasting biology

Biodiversity of sharks in the tropical Indo-Pacific is high, but species-specific information to assist sustainable resource exploitation is scarce. The null hypothesis of population genetic homogeneity was tested for scalloped hammerhead shark (Sphyrna lewini, n = 237) and the milk shark (Rhizoprionodon acutus, n = 207) from northern and eastern Australia, using nuclear (S. lewini, eight microsatellite loci; R. acutus, six loci) and mitochondrial gene markers (873 base pairs of NADH dehydrogenase subunit 4). We were unable to reject genetic homogeneity for S. lewini, which was as expected based on previous studies of this species. Less expected were similar results for R. acutus, which is more benthic and less vagile than S. lewini. These features are probably driving the genetic break found between Australian and central Indonesian R. acutus (F-statistics; mtDNA, 0.751–0.903, respectively; microsatellite loci, 0.038–0.047 respectively). Our results support the spatially homogeneous monitoring and management plan for shark species in Queensland, Australia.     

脱水红霉素对蛋白核小球藻的生态毒性效应研究

脱水红霉素是环境中普遍存在的一种大环内酯类抗生素,其生态毒性效应尚不明确。因此,以蛋白核小球藻(Chlorella pyrenlidosa)为受试生物,研究了脱水红霉素对绿藻的生长、叶绿素a含量、抗氧化酶活性和丙二醛(MDA)含量的影响。结果表明,脱水红霉素对蛋白核小球藻的生长具有抑制作用,且随暴露浓度的升高而增强。脱水红霉素对蛋白核小球藻的96 h比生长率半数抑制浓度(E_rC_(50))和生长量半数抑制浓度(E_yC_(50))分别为0.267和0.117 mmol·L~(-1),属于中-低毒物质。脱水红霉素暴露对蛋白核小球藻的叶绿素a含量、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和MDA含量具有重要影响。叶绿素a含量随脱水红霉素浓度升高而降低; SOD酶活性升高,但与脱水红霉素浓度之间不存在剂量效应关系,CAT酶活性和MDA含量随脱水红霉素升高而升高,说明脱水红霉素对蛋白核小球藻具有氧化胁迫效应。暴露96 h后,藻液中脱水红霉素的去除率随其初始浓度增加而增加,在脱水红霉素初始浓度为0.87 mmol·L~(-1)时,其去除率可达到43%。研究结果可为脱水红霉素的生态风险评估提供理论依据。     

Evaluation of the toxicity of tetrabromobisphenol A and some of its oxidation products using a micro-scale algal growth inhibition test

A micro-scale algal growth inhibition (μ-AGI) test using a common micro-plate based fluorometric detection was used to demonstrate the effects of humic substances (HSs) on the toxicity of tetrabromobisphenol A (TBBPA) and its oxidative decomposition products 2,5-dibromo-1,4-benzoquinone (2,5-DBBQ), 2,5-dibromohydroquinone (2,5-DBHQ), 2,6-dibromobenzoquinone (2,6-DBBQ), and 2,6-dibromophenol (2,6-DBP) to Pseudokirchneriella subcapitata. The EC₅₀ values were: EC_50(TBBPA) = 7 mg L^?1, EC_50(2,5-DBHQ) = 7 mg L^?1, EC_50(2,5-DBBQ) = 19 mg L^?1, EC_50(2,6-DBP) = 49 mg L^?1, and EC_50(2,6-DBBQ) = 13 mg L^?1. The toxicity of the chemicals was slightly lower in the presence of HA. The toxicity of TBBPA decomposed by a biomimetic catalytic system consisting of iron (III) 5,10,15,20-tetrakis (p-sulfonatophenyl) porphyrin (Fe(III)-TPPS) and KHSO₅ was also evaluated using P. subcapitata and Chlamydomonas reinhardtii.     

The effects of temperature,body size and growth rate on energy losses due to metabolism in early life stages of haddock (<Emphasis Type="Italic">Melanogrammus aeglefinus</Emphasis>)

Rates of routine respiration (R _R, μl O₂ fish⁻¹ h⁻¹) and total ammonia nitrogen excretion (E _R, μg NH₄–N + NH₃–N fish⁻¹ h⁻¹) were measured on larval and juvenile haddock (Melanogrammus aeglefinus) to ascertain how energy losses due to metabolism were influenced by temperature (T), dry body mass (M _D, mg) and specific growth rate (SGR, % per day). R _R and E _R increased with M _D according to y = a  · M _D ^b with b-values of 0.96, 0.98, 1.14, and 0.89, 0.78, 0.74, respectively, at 10, 7, and 4°C, respectively. Multiple regressions explained 98% of the variability in the combined effects of M _D and T on R _R and E _R in larval haddock: R _R = 0.97 · M _D ^0.98  · e^0.092 · T ; E _R = 0.06 · M _D ^0.79  · e^0.092 · T . In young juvenile (24–30 mm standard length) haddock, R _R tended to decline (P = 0.06) and E _R significantly declined (P = 0.02) with increasing SGR. O:N ratios significantly increased with increasing SGR suggesting that N was spared in relatively fast-growing individuals. Our results for young larval and juvenile haddock suggest: (1) nearly isometric scaling of R _R with increasing body size, (2) allometric scaling of E _R with increasing body size, (3) Q ₁₀ values of 2.5 for both R _R and E _R, (4) metabolic differences in substrate utilization between relatively fast- and slow-growing individuals, and (5) that rates of routine energy loss and growth were not positively related. The measurements in this study will provide robust parameter estimates for individual-based models that are currently being utilized to investigate how variability in climatic forcing influences the vital rates of early life stages of haddock. Our results also stress that inter-individual differences in rates of energy loss should not be overlooked as a factor influencing growth variability among individuals.     

Spring sea ice photosynthesis,primary productivity and biomass distribution in eastern Antarctica, 2002–2004

While it is known that Antarctic sea ice biomass and productivity are highly variable over small spatial and temporal scales, there have been very few measurements from eastern Antarctic. Here we attempt to quantify the biomass and productivity and relate patterns of variability to sea ice latitude ice thickness and vertical distribution. Sea ice algal biomass in spring in 2002, 2003 and 2004 was low, in the range 0.01–8.41 mg Chl a m⁻², with a mean and standard deviation of 2.08 ± 1.74 mg Chl a m⁻² (n = 199). An increased concentration of algae at the bottom of the ice was most pronounced in thicker ice. There was little evidence to suggest that there was a gradient of biomass distribution with latitude. Maximum in situ production in 2002 was approximately 2.6 mg C m⁻² h⁻¹ with assimilation numbers of 0.73 mg C (mg Chl a)⁻¹ h⁻¹. Assimilation numbers determined by the ¹⁴C incubations in 2002 varied between 0.031 and 0.457 mg C (mg Chl a)⁻¹ h⁻¹. Maximum fluorescence quantum yields of the incubated ice samples in 2002 were 0.470 ± 0.041 with E _k indices between 19 and 44 μmol photons m⁻² s⁻¹. These findings are consistent with the shade-adapted character of ice algal communities. In 2004 maximum in situ production was 5.9 mg C m⁻² h⁻¹ with an assimilation number of 5.4 mg C (mg Chl a)⁻¹ h⁻¹. Sea ice biomass increased with ice thickness but showed no correlation with latitude or the time the ice was collected. Forty-four percent of the biomass was located in bottom communities and these were more commonly found in thicker ice. Surface communities were uncommon.     

Relationship between cooling rates,cryoprotectant concentrations and salinities in the cryopreservation of marine microalgae

The viability of the marine microalgae Rhodomonas baltica Karsten, Isochrysis affinis galbana (Strain T-ISO) Parke, Chaetoceros gracilis Schütt, Tetraselmis chuii Butcher, Nannochloropsis gaditana Lubian and Nannochloris atomus Butcher, cryopreservec employing different cooling rates, either with or without the addition of the cryoprotective compounds dimethyl sulfoxide (DMSO) and methanol was studied at two exposure salinities. A viability index, which considered both cell recovery and the growth capacity of microalgae after thawing, was developed. The growth of thawed algae was compared to that obtained for unfrozen algae grown in liquid medium under the same conditions. Viability (V) was calculated according to the equation: V=(C ₀/C _i)x(C ₇/(a·C ₀ ^b ))x100, where C ₀ and C ₇ are, respectively, the initial and final cell densities measured in the cultures after thawing from-196°C, C _i is the maximum initial cell density (complete cell recovery), and a, b are the regression coefficients obtained for C ₇ as a function of C ₀ in the unfrozen controls. R. baltica was the only species that showed an improved viability when salinity was reduced from 36 (average viability 13.7% for 15% DMSO) to 20 (average viability 36.2% for 15% DMSO). The other five species displayed better viability only at the higher salinity at all tested cooling rates and cryoprotectant levels. T. chuii, Nannochloropsis gaditana, and Nannochloris atomus Butcher could be cryopreserved without cryoprotectant. However, their respective viabilities (32.7, 30.8 and 65.8%) at 36 S were progressively improved on addition of 5% DMSO (70.9, 48.2 and 93.5, respectively) and 15% DMSO (91.9, 57.0 and 94.2%, respectively). Similar improvements were found for Nannochloropsis gaditana and Nannochloris atomus when cryopreserved using methanol concentrations of 1% (average viabilities of 46.9 and 91.8, respectively) and 5% (average viablities of 48.7 and 95.3, respectively). Methanol was completely ineffective in cryopreserving the other four species and caused a lethal effect on T. chuii during freezing. C. gracilis could be cryopreserved with 5% DMSO only at 36 S. This resulted in a similar viability (11.7%) to that obtained using 15% DMSO in 20 S (13.7%). Keeping cryoprotectant concentration at 15% DMSO and raising salinity to 36 significantly improved the mean viability of C. gracilis to 21.6%. A low mean viability of 2.1% was obtained for I. galbana when 15% DMSO was used in full-strength seawater (36 S). Within the range of cooling rates tested (0.25 to 16 C° min^-1), cryopreserved microalgae showed higher viabilities at faster rates in the absence of cryoprotectants at both salinities. Generally, the dependence on cooling rate decreased proportionally to the concentration of DMSO or methanol, as demonstrated by the lack of significance for the slope of the regressions. Only C. gracilis appeared to depend on faster cooling rates in the presence of 15% DMSO.     

Effects of metal pollution in the monosodium glutamate production effluent on full exploitation and biological treatment

Monosodium glutamate (MSG) effluent was sampled from three MSG mills and 21 metal elements were measured with a inductively coupled plasma (ICP) Spectrometer. The total metal concentration of each MSG wastewater sample was 19192, 3190 and 3161 mg/L respectively. Compared with the water quality standard issued by the Chinese Government and the World Health Organization (WHO), some values were found to exceed the standards. The 24hr‐LC₅₀, 48hr‐LC₅₀, 72hr‐LC₅₀ and 96hr‐LC₅₀ to the fish Ctenopharyngodon idellus were 6.9%, 3.2%, 2.5% and 1.4% MSG wastewater individually. The specific growth rate for photosynthetic bacteria (PSB) Rhodopseudomonas sphaeroides was inhibited by the metals in MSG wastewater. Therefor the MSG wastewater should not be discharged into drinking, irrigation and fishery water systems, moreover it cannot be treated by general biological processes efficiently. How to develop an effective biotechnique for the utilization of organic pollutants in MSG effluent will also be discussed in this paper.     

Saturated and unsaturated hydrocarbons in marine benthic algae

Saturated and olefinic hydrocarbons were determined in 24 species of green, brown and red benthic marine algae from the Cape Cod area (Massachusetts, USA). Among the saturated hydrocarbons, n-pentadecane predominates in the brown and n-heptadecane in the red algae. A C₁₇ alkyleyclopropane has been identified tentatively in Ulvalactuca and Enteromorpha compressa, two species of green algae. Mono-and diolefinic C₁₅ and C₁₇ hydrocarbons are common. The structures of several new C₁₇, C₁₉ and C₂₁ mono-to hexaolefins have been elucidated by gas chromatography, mass spectrometry and ozonolysis. In fruiting Ascophyllum nodosum, the polyunsaturated hydrocarbons carbons occur exclusively in the reproductive structures. The rest of the plant contains n-alkanes from C₁₅ to C₂₁. A link between the reproductive chemistry of benthic and planktonic algae and their olefin content is suggested. An intriguing speculation is based on Paffenhöfer's (1970) observation that the sex ratio of laboratory reared Calanus helgolandicus depends upon the species of algae fed to the nauplii. The percentage of males produced correlates with our analyses of heneicosahexaene in the algal food. Our analyses of the hydrocarbons in benthic marine algae from coastal environments should aid studies of the coastal food web and should enable us to distinguish between hydrocarbon pollutants and the natural hydrocarbon background in inshore waters.Contribution No. 2582 of the Woods Hole Oceanographic Institution; and Contribution No. 227, Systematics-Ecology Program.     

Metabolism,enzymic activities and cold adaptation in Antarctic mesopelagic fishes

Several species of Antarctic mesopelagic fishes that have different minimal depths of occurrence but the same environmental temperature were collected in November–December 1983 and in March 1986 between 0 and 1 000 m in the open water near the marginal ice zone in the vicinity of 60°S 40°W (1983) and 65°S 46°W (1986), and oxygen consumption rate (V _{O 2}) and the activity of two metabolic enzymes, lactate dehydrogenase (LDH, an indicator of the anaerobic potential of locomotory muscle) and citrate synthase (CS, an indicator of citric acid cycle activity or aerobic potential), were determined. In four dominant species, whole-individual oxygen-consumption rate (y, ml O₂ individual^–1 h^–1) varied with weight (X, g) according to the equation y=aX ^b, with b values falling between 0.889 and 1.029. The relation of weight-specific LDH activity (y, U g^–1 wet wt) with weight (x, g) was also described by the equation y=aX ^b, with b values varying between 0.229 and 1.025. Weight-specific CS activity declined with weight, with b values from-0.031 to-0.369. V _{2 O}, LDH activity and CS activity all declined markedly with increased species' minimum depth of occurrence (the depth below which 90% of a species' population lives). Comparisons with previous studies on ecologically equivalent species of the California Borderland indicate that depth-related decreases in metabolism are the result of adapted traits of deeper-living species, not declining temperature within the water column. The metabolic rate of Antarctic mesopelagic fishes is approximately twice that of California species at equivalent temperatures; similar rates were found at the normal habitat temperatures of the two groups. Thus, a well-developed compensation for temperature is present in the Antarctic fishes: cold adaptation. Differences in enzymic activity among species, and among different sized individuals of a species are related to differences in metabolic rate and locomotory capacity. Enzymic indices can be used to estimate metabolic rates and evaluate ecological parameters such as predatory strategies and niche separation.     

Effects of dietary fatty acids on the reproductive success of the calanoid copepod<Emphasis Type="Italic"> Temora longicornis</Emphasis>

Egg production and hatching success of the copepod Temora longicornis were measured in laboratory experiments and in the field (North Sea). In the laboratory, ingestion of four algal species (Thalassiosira weissflogii, Phaeocystis globosa, Isochrysis sp. and Dunaliella tertiolecta) was followed and the content of fatty acids in the algae was determined. The two food types (T. weissflogii and Isochrysis sp.) that provided the highest ingestion of carbon and long chain fatty acids also resulted in the highest egg production rate (E_r) and hatching success (H%). In contrast, D. tertiolecta led to both low ingestion of carbon and long chain fatty acids, resulting in low reproductive success. There was a positive relationship between the amount of eicosapentaenoic fatty acid [20:5(n-3), EPA] ingested and E_r and H%, and of the ratio between docosahexaenoic and eicosapentaenoic fatty acid [22:6(n-3)/20:5(n-3), DHA/EPA] in the ingested food and H%. In the field, chlorophyll a and specific fatty acids were measured and protists were enumerated, in order to investigate the link between these factors and the reproductive success of T. longicornis. Hatching time was found to be related to temperature and exceeded 120 h at 6°C. No relationship was found between chlorophyll a and reproductive success (E_r or H%). E_r correlated with the concentration of diatoms and ciliates, which were the dominating protists in early spring, indicating that food quantity was the limiting factor for E_r. As in the laboratory experiments, H% was dependent on the fatty acid DHA and the ratio of DHA/EPA, which indicates that the quality of eggs (H%) is linked to the quality of food.Communicated by M. Kühl, Helsingør     

Screening bamboo species for salt tolerance using growth parameters,physiological response and osmolytes accumulation as effective indicators

Bamboos are potential species for reclamation of saline soils and water. In this study, the performances of three bamboo species, namely Dendrocalamus strictus (S1), Dendrocalamus longispathus (S2) and Bambusa bambos (S3), were investigated for salinity stress tolerance. After 14 days of treatment with 100?mM NaCl, reduction in shoot length was 66%, 100%, 77%, root length was 77%, 100%, 57%, number of leaves was 50%, 100%, 73% and fresh weight was 30%, 72%, 14% in S1, S2 and S3 species, respectively. Relative water content (RWC) in S1 and S3 species was 1.26 and 1.07 folds higher in 50?mM NaCl in comparison to control. In S2 species, total chlorophyll, chlorophyll_a and chlorophyll_b degradation were the highest (40.4%, 42.7%, 16.32%, respectively) in comparison to S3 (18.18%, 23%, 16.4%) and S1 (23.5%, 25%, 19.17%) species. In S3 and S1 species, the Chl_a/Chl_b ratio was maintained showing stabilisation of the net photosynthetic rate. Proline played a more important role than glycine betaine for salt tolerance of these bamboo species. On account of vegetative growth, proline accumulation and RWC, it is inferred that S1 and S3 species are salt tolerant while S2 is a sensitive species.

Abbreviations: SL: shoot length; RL: root length; NL: number of leaves; FW: fresh weight; RWC: relative water content; Chl_a: chlorophyll_a; Chl_b: chlorophyll_b; TC: total chlorophyll; GB: glycine betaine     

Ingestion rate,assimilation efficiency and energy balance in Mytilus chilensis in relation to body size and different algal concentrations

Basing on a quantification of filtration, ingestion, assimilation, biodeposition, excretion and respiration rate, energy budgets were established in Mytilus chilensis Hupé in relation to body size and three different food concentrations of the unicellular green alga Dunaliella marina. The present quantifications revealed that in M. chilensis the ingestion rate only increases slightly with an increase in food concentration which, however, is counterbalanced by a significant decrease in assimilation efficiency in such a way that assimilation rate finally is nearly constant and independent of the food concentrations tested. The quantifications of these results are given by the a-values of the general allometric growth equation P=aW^b relating the energy disposable for growth and reproduction (P; cal d^-1 to body size (W; dry-tissue wt, g). The best energy budget was obtained at the lowest food concentration tested (0.8 mg algal dry wt l^-1; at 12°C and 30 S) with an a-value of 58.8, while the energy budget at the highest food concentration (2.14 mg l^-1) was only slightly lower with an a-value of 49.8; the b-values were 0.49 and 0.51, respectively. The net growth efficiencies (K₂) decreased with increasing body size (from 20 mg to 3 000 mg drytissue wt) from 76.7 to 47.9% at the lowest food level and from 72.6 to 44.0% at the highest food level tested. These relatively high net growth efficiencies seem to reflect optimal experimental conditions. Furthermore, by a comparison of estimated growth (calculated on the basis of the best energy budget) with growth actually quantified in culture raft mussels in the south of Chile during the highest production period of the year, it is obvious that the energy budgets established really reflect the conditions experienced by the mussels in their natural environment.This research was supported by grants S-80-3 and C-80-1 of the D.I.D.-UACH, by CONICYT, Found. Volkswagenwerk, Found. Fritz-Thyssen, by the GTZ, DFG and by the DAAD     

Persistence of atrazine impact on aneuploidy in Pacific oysters,<Emphasis Type="Italic"> Crassostrea gigas</Emphasis>

Widespread use of the herbicide atrazine has incited much research on its toxicity in aquatic systems, where it is routinely detected due to runoff from cultivated fields. Moreover, the determination of the genotoxic effect of such pollutants in the marine environment has become a major requirement for ecosystem protection. In the Pacific oyster, Crassostrea gigas, hypodiploid aneuploid cells have regularly been reported. There is a negative correlation between this phenomenon and growth, as well as evidence for a genetic basis. A positive relationship between atrazine and aneuploidy has previously been demonstrated in C. gigas adults and juveniles. To evaluate the persistence of this impact, our study examined the offspring of the same adult population previously treated with different atrazine doses (10 µg l^–1, representing a peak value found in a polluted environment and 100 µg l^–1), and a seawater control. We observed that these offspring exhibited significantly higher aneuploidy levels when their parents had been exposed to atrazine (14.9–16.9% in comparison with the control where the levels ranged from 11.4% to 12.8%). In addition, the present study examined the aneuploidy level of a sample of juveniles, previously exposed for 3.5 months to the same doses of atrazine, then transferred to non-polluted conditions for an additional period of 2.5 months; this aneuploidy level remained significantly different between the treatments applied. These results demonstrate the persistence of an atrazine impact on Pacific oyster aneuploidy in time, within and between generations, indicating that this widely used compound may represent an important factor causing at least medium-term damage to genetic material.Communicated by S.A. Poulet, Roscoff