SEASONAL SUCCESSION OF PHYTOPLANKTON IN LAKE PRINCE, SUFFOLK, VIRGINIA: PRELIMINARY REPORT

Lake Prince is a reservoir lake that provides the region with drinking water, recreational boating, and fishing. The Virginia Department of Game and Inland Fisheries has an interest in the quantity and quality of phytoplankton production in the lake, especially regarding the health of fish populations. Another concern in this reservoir is oxygen availability, and aerators have been installed in the main body of the lake. A year-long examination of the phytoplankton community structure is being conducted. Duplicate surface water samples are collected monthly from three stations, along with physical and chemical baseline data. Community structure and dominance are being examined with regard to the physical and chemical parameters, as well as seasonal climate changes. Cyanobacteria and Cryptophytes are the dominant spring flora. Diatoms and Chrysophytes are sub-dominant populations.     

SEASONAL PRIMARY PRODUCTION OF UNDERSTORY RHODOPHYTA IN AN UPWELLING SYSTEM1

The in situ primary production of three common under-story members of the Rhodophyta in South African west coast kelp beds was determined monthly for a year using dissolved oxygen techniques. Strong seasonal patterns of photosynthesis and respiration were evident in all three species. Net photosynthesis of all three species was greatest in spring (October) and lowest in winter (June). Increasing photosynthesis in late winter coincided with increasing ambient irradiance and photoperiod, whereas decreasing photosynthesis in summer was not explained by changes in the environmental parameters measured. We suggest that this may he due to an innate pattern related to some other seasonal plant activity such as reproduction. Seasonal P_max and I_k values reveal that the obligate understory species, B. prolifera and E. obtusa, are shade-adapted whereas G. radula, a low intertidal and shallow subtidal dominant, is sun-adapted. Low C: X ratios consistent with a high nutrient environment and high rates of productivity were found in all three species. Net photosynthesis to respiration (Pn:R) ratios were fairly constant for B. prolifera and E. obtusa, implying that then photosynthetic processes were governed more by seasonal variations in irradiance than by instantaneous light availability. The Pn: R ratio of G. radula was variable, suggesting that this species is more responsive to rapid fluctuations in irradiance and may therefore be adapted for rapid growth during periods of high irradiance.     

SEASONAL DIFFERENCES IN THE TEMPERATURE RANGES OF GROWTH OF VIRGINIA ALGAE1

One hundred and fifteen clonal, unialgal strains were isolated and tested for their ability to grow over a range of temperatures from 2 to 40° C. Responses of 63 strains isolated from habitats that were 6° C when sampled and 52 strains isolated from habitats that were 20° C when sampled showed trends toward increasing adaptation to cold or warm temperatures commensurate with their seasonal in situ temperatures. Based on temperature-growth responses alone, 24% of the plankton isolates and 17% of the periphyton isolates could be perennial within the natural habitats. At 5° C, 56% of the warm water plankton isolates and 48% of the warm water periphyton isolates were incapable of growth and, therefore, probably could not be important components of the winter algal community. Likewise at 25° C, 25% of the cold water plankton isolates and 13% of the cold water periphyton isolates were incapable of growth. Thus, temperature alone probably is an important variable regulating seasonal changes in algal community structure. Pollution of these habitats by a thermal enrichment averaging + 5° C year-round could effect a pronounced change in algal species composition because many more taxa could be perennial and more taxa would be incapable of growth during naturally warm periods.     

PHYTOPLANKTON OF THE SUSQUEHANNA RIVER NEAR BINGHAMTON,NEW YORK: SEASONAL VARIATIONS; EFFECT OF SEWAGE EFFLUENTS1,2

Net phytoplankton samples were collected weekly for 13 months at points above and below sewage effluents. Sixty-three genera and 130 taxa were identified: diatoms, 19 genera, 44 taxa; greens, 31 genera, 67 taxa; blue-greens, 6 genera, 8 taxa. Downstream from the sewage effluents the number of taxa was unchanged but the number of organisms was definitely increased. This increase was most pronounced for green and blue-green algae, and least for diatoms. The seasonal distribution of algae was that usually seen in waters of the North Temperate Zone. The particular taxa and number of taxa found were those of productive waters but not typical of heavily polluted waters.     

FLOATING COMMUNITIES OF ALGAE IN AN ARTIFICIAL POND IN THE PARQUE DO ESTADO,SÃO PAULO,BRAZIL1

A fresluvater floating algal community was repeatedly observed in an artificial pond in the Parque do Estado São Paulo, Brazil. The ontogeny and composition of the community are discussed and are related to oxygen liberation during photosynthesis of the periphyton, or of the pond-bottom algne, which carries up portions of the algae growing there.     

SEASONAL VARIATIONS IN RESERVE AND STRUCTURAL COMPONENTS OF PINUS RESINOSA CONES

Changes in reserve materials, lignin, hemicellulose, and cellulose of 1st-year conelets and 2nd-year cones of red pine (Pinus resinosa Ait.) were studied by chemical extraction of the respective fractions. During the first 11 months after emergence of conelets, reserve materials, primarily carbohydrates, constituted approximately half of the dry weight of cones. Cellulose and hemicellulose contents were low but cells were highly lignified. During summer of the 2nd year of cone development, marked compositional changes occurred. A rapid surge of cone growth, possibly triggered by resumption of pollen-tube growth and fertilization, occurred from mid-June to early August and was accompanied by transformation of reserve materials into cellulose and, to a lesser extent, into hemicellulose and lignin. During this transformation, the thickening and lignification of cells responsible for the opening of cone scales probably occurred. The developing seeds also mobilized readily available cone reserves during this time.     

社鼠消化道长度和重量的季节变化

社鼠消化道长度和重量的季节变化ＳＥＡＳＯＮＡＬＶＡＲＩＡＴＩＯＮＳＩＮＬＥＮＧＴＨＡＮＤＷＥＩＧＨＴＯＦＤＩＧＥＳＴＩＶＥＴＲＡＣＴＩＮＲＡＴＴＵＳＮＩＶＩＶＥＮＴＥＲＣＯＮＦＵＣＩＡＮＵＳ关键词社鼠消化道形态季节动态ＫｅｙｗｏｒｄｓＲａｔｕｓｎｉｖ...     

达乌尔黄鼠产热的季节性变化

达乌尔黄鼠（Ｃｉｔｅｌｌｕｓｄａｕｒｉｃｕｓ）的产热表现出明显的季节性变化。在非冬眠期,静止代谢率（ＲＭＲ）和非颤抖性产热（ＮＳＴ）于春季最高,秋季次之,夏季最低。冬眠期,ＲＭＲ降到极低水平,只为春季的３．０％。肝脏的线粒体蛋白含量、线粒体呼吸和细胞色素Ｃ氧化酶活力在秋季显著高于其它各季。褐色脂肪组织（ＢＡＴ）的重量、线粒体蛋白含量、细胞色素Ｃ氧化酶活力和α－磷酸甘油氧化酶活力,在夏季处于一年中的最低水平,到了冬季这些指标达到一年中的最高水平。在非冬眠季节ＢＡＴ产热能力升高时,ＮＳＴ能力也相应升高,这表明ＢＡＴ产热能力的增强是ＮＳＴ能力提高的部分机制。达乌尔黄鼠血清Ｔ＿４含量在年周期中没有明显改变,冬眠时血清Ｔ＿３含量显著高于其它各季。     

长湖浮游植物优势种季节演替及生态位分析

为查明长湖浮游植物优势种群落结构特征及季节演替规律,于2015年4月至2016年1月对长湖浮游植物群落结构及相关环境因子进行了调查,同时利用典范对应分析法(CCA)进行浮游植物优势种与环境因子的相关性分析。结果表明:本次调查共鉴定出浮游植物优势种共14种,其中扭曲小环藻(Cyclotella comta)、小球藻(Chlorella vulgaris)和梭形裸藻(Euglena acus)是4个季节的共有优势种。生态位宽度(Niche width)变化范围为1.002—2.377,其中夏季小球藻最高,广生态位种类以富营养化水体常见指示种小球藻、扭曲小环藻、两栖颤藻(Oscillatoria amphibia)等种类为主。平均边缘指数(OMI)变化范围为0.25—3.71,其中小于1的物种共12种。耐受指数(TOI)变化范围为0.13—3.35,夏季两栖颤藻最高。生态位重叠值的变化范围为0.02—0.93,其中秋季扭曲小环藻和梭形裸藻的重叠值最高。选取7个环境因子与浮游植物优势种进行CCA分析发现:夏季微小平裂藻(Merismopedia tenuissima)、两栖颤藻、四尾栅藻、扭曲...     

长江中游湖泊不同鱼类养殖方式对浮游植物群落的影响

为研究水产养殖对湖泊生态系统的影响, 于2015年7月至9月对长江中游23个湖泊的浮游植物群落及生物多样性情况进行了调查, 所研究的湖泊包括以下4组: 水库组(A组)、禁养组(B组)、低密度养殖组(C组)、高密度养殖组(D组)。结果显示, 4组湖泊的优势类群间存在一定差异。A组优势种有假鱼腥藻(Pseudanabaena, Y=0.642, Y为优势度)、浮鞘丝藻(Planktolyngbya, Y=0.064), B组优势种有平裂藻(Merismopedia, Y=0.428)、浮鞘丝藻(Planktolyngbya, Y=0.118)、假鱼腥藻(Pseudanabaena, Y=0.133)、栅藻(Scenedesmus, Y=0.066), C组优势种为假鱼腥藻(Pseudanabaen, Y=0.395)、平裂藻(Merismopedia, Y=0.097)、浮鞘丝藻(Planktolyngbya, Y=0.122), D组的优势种为平裂藻(Merismopedia, Y=0.308)、微囊藻(Microcystis, Y=0.118)、假鱼腥藻(Pseudanabaena, Y=0.077)。A组浮游植物丰度显著低于B组、C组及D组(P<0.05)。各组间浮游植物群落的Shannon-Wiener多样性指数、Margalef丰富度指数及Pielou均匀度指数均不存在明显差异。研究表明鱼类养殖对湖泊浮游植物的丰度及优势类群会产生影响, 对湖泊生态系统的管理具有一定的参考意义。     

SEASONAL PATTERN OF DIEL PERIODICITY IN PHOTOSYNTHESIS BY POLAR PHYTOPLANKTON: SPECIES-SPECIFIC RESPONSES1

The diel patterns of light-saturated and light-limited photosynthesis were measured for three diatom species in McMurdo Sound, Antarctica during the transition from late austral winter to summer. Maximum photosynthetic capacity occurred around mid-day during September, when there was a well defined light/dark cycle, and progressively shifted to about midnight by late october when irradiance was continuous. There was a concomitant shift in minimum photosynthetic capacity from midnight to midday. Rates of light-saturated and -limited photosynthesis covaried, and the magnitude of seasonal and diel changes in photosynthetic characteristics were similar. The linear relationship between light-saturated and -limited photosynthesis suggests that the shapes of the photosynthesis-irradiance curves remained relatively constant over the day and througout the season. The unique diel patterns of photosynthesis of these polar phytoplankton appear to be a response to the persistently low, yet continuous irradiance of the polar summer.     

沙颍河下游城市黑臭内河沉积物微生物群落季节变化特征

为了研究沙颍河下游城市黑臭内河不同季节沉积物微生物群落特征,对安徽省阜阳市黑臭内河中清河、七渔河表层沉积物进行16S rDNA高通量测序。结果发现:黑臭河流中沉积物的微生物多样性指数均不高,但是表现出一定的变化规律,即春季>冬季≥夏季>秋季;通过冗余性分析发现微生物多样性受季节与沉积物pH影响较显著。分析沉积物门水平上的微生物群落结构发现,季节、温度、TN及SOM对微生物影响较大。变形杆菌、厚壁菌门、绿弯菌门、疣微菌门、拟杆菌门和放线菌门等优势菌门的相对丰度在季节水平上存在差异,春季厚壁菌门、绿弯菌门、放线菌门和酸杆菌门相对丰度较高,其中绿弯菌门和酸杆菌门是已知指示污染的微生物,变形杆菌门相对较少。秋季疣微菌门与拟杆菌门相对丰度显著减小,变形杆菌门相对其他季节显著增加。样品中共发现16个硫酸盐还原菌(SRB)菌属,其中Desulfoprunum是丰度最高的菌属。春季沉积物中SRB的类群最多,相对丰度最大;硫酸盐还原菌群与SO42-、TN、SOM、Cl–等呈显著正相关。上述结果为营养盐控制时机的选择从而有效避免河流中黑臭物质的产生提供了一定参考。     

SEASONAL VARIATIONS IN THE PROPORTIONS OF SUBERIZED AND UNSUBERIZED ROOTS OF TREES IN RELATION TO THE ABSORPTION OF WATER

Growing root tips usually constituted less than 1 per cent and mycorrhizal roots less than 6 per cent of the total root surface under a 34-year-old pine stand. Growing root tips usually constituted less than 1 per cent of the total root surface under a yellow poplar stand, although one sample taken in May contained 9 per cent of unsuberized roots. The water permeability of various types of roots was measured under a pressure gradient of 31 cm of mercury. It differed widely among individual roots, ranging from an average of 6.6. mm³/cm²/hr for suberized pine roots 1.33 mm in diameter, to 36.6 mm³ for suberized pine roots 3 mm in diameter, and 178 mm³/ cm²/hr for unsuberized roots grown in water culture. Water intake through a group of unsuberized roots grown in soil averaged 37.4 mm³/cm²/hr. The permeability of yellow poplar roots varied even more, ranging from essentially zero to 30,000 mm³/cm²/hr. It is concluded that the major part of water absorption in pine occurs through suberized roots, some through mycorrhizal roots, and relatively little through growing root tips. Likewise, in yellow-poplar most of the water probably enters through suberized roots. Further study is needed of the role of suberized roots in water and salt absorption.     

西湖湖西浮游与着生藻类季节变化及相互关系

2014年11月至2015年8月调查了西湖湖西沿岸带浮游藻类和不同基质(植物、石块和底泥)上着生藻类的群落结构及季节变化, 分析了着生丝状藻与浮游丝状藻的相互关系以及它们与环境因子的相关性, 探讨湖西生态修复过程中季节性暴发的丝状藻水华的原因。结果表明浮游藻类和植物、底泥、石头上着生藻类中均以硅藻门种类数(分别占52.5%、60.4%、86.7%和72.7%)最多, 蓝藻门(分别占10.1%、8.9%、6.7%和15.2%)和绿藻门(分别占26.3%、19.8%、5.6%和10.6%)次之, 其他门类相对较少, 浮游藻类与着生藻类优势种季节差异较大。附植丝状藻密度显著高于附泥和附石丝状藻, 且狐尾藻上着生丝状藻密度与浮游丝状藻密度呈显著正相关, 表明狐尾藻着生丝状藻可能是浮游丝状藻较重要的来源之一, 该结果可为西湖丝状藻水华的控制提供一些参考。相关性分析表明, 着生藻类和丝状藻与各理化因子(水深、透明度、溶解氧、水温、pH、TN、SRP、TP等)均无显著相关性。     

稻虾共作水体浮游植物群落结构特征分析

为认识稻虾共作水体浮游植物群落结构特征, 于2016年4月至12月对江汉平原4处稻虾共作水体浮游植物和理化因子开展了逐月调查与分析。共鉴定出浮游植物7门124种, 其中绿藻78种、蓝藻16种、硅藻15种、裸藻3种、隐藻2种、甲藻7种、金藻3种。6—9月浮游植物的种类数、细胞密度、叶绿素a含量达到最大值, 最小值出现在12月份; 浮游植物细胞密度波动范围在1.37×105—2.93×108 cells/L, 叶绿素a含量的变化范围为0.15—208.60 μg/L。调查期间浮游植物的优势种共28种, 主要优势种有颤藻、蓝纤维藻、微囊藻、小球藻、隐藻等。浮游植物Shannon-Wiener多样性指数周年变化范围为0.64—6.3, 多样性指数最高出现在10月份, 最低出现在8月份。结果显示, 稻虾共作水体浮游植物群落结构较复杂, 细胞密度变化显示时空的一致性, 优势种组成以及优势度存在明显的空间差异(P<0.05), 稻田的浅水环境以及小龙虾的养殖行为显著影响浮游植物群落的结构。鉴于藻类作为初级生产者对于水生态环境和小龙虾健康具有重要作用, 关注种养结合水体中藻类群落的演变规律对于保障稻田种养的综合效益具有积极意义。