SEASONAL FLUCTUATIONS IN TISSUE NITROGEN FOR FIVE SPECIES OF PERENNIAL MACROALGAE IN RHODE ISLAND SOUND1

Tissue nitrogen was assessed monthly for 16 months in five species of perennial macroalgae representing three phyla at one location in Rhode Island Sound. The species showed a remarkable similarity in their pattern of seasonal fluctuation in both nitrate and total nitrogen. The period of greatest accumulation (January through March) coincided with the period of highest concentration of inorganic nitrogen in the water, and for most of these algae it was also the time of-least growth. Conversely, the period of lowest tissue nitrogen (50% of the winter value, May through July) coincided with the period of lowest inorganic nitrogen in the water and highest algal growth. The greatest accumulation of nitrate was found in Laminaria saccharina (L.) Lamour. (80 μmol·g dry wt.^?1), four times as much as that measured simultaneously in the other species and 560 times the ambient concentration. By April the concentration of internal nitrate had dropped to nearly undetectable levels, but in August it began to accumulate again—a pattern that was repeated in Chondrus crispus Stackh. In Ascophyllum nodosum (L.) Le Jolis, Fucus vesiculosus L. and Codium fragile subsp. tomentosoides (Van Goor) Silva, the period of negligible internal nitrate level extended from March to December. The greatest concentration of total tissue nitrogen was measured in C. crispus (4.8% dry wt.), double the maximum in L. saccharina (2.3% dry wt.).     

海南西部近岸浮游植物的周年变化及主要关联因素

报道了2008—2009年4季度海南西部近岸浮游植物群落的周年动态并探讨其主要关联因素。165份样品经鉴定共有浮游植物4门74属155种(含5变型和2变种),周年平均丰度为(6.36±4.75)×103cells/L。硅藻在物种组成和丰度上均占绝对优势,其次为甲藻,蓝藻(束毛藻)在7月增殖。主要优势种为菱形海线藻(Thalassionema nitzschioides)、奇异棍形藻(Bacillaria paradoxa)、具槽帕拉藻(Paralia sulcata)、旋链角毛藻(Chaetoceros curvisetus)、笔尖根管藻(Rhizosolenia styliformis)、束毛藻(Trichodesmium spp.)、海洋原甲藻(Prorocentrum micans)等。物种组成的季节差异较大,10月浮游植物种类贫乏,1月次之,4月、7月最丰富。丰度10月最高,季节差异并不明显。束毛藻在4月、7月呈斑块状群聚分布。浮游植物周年平均丰度并不高(<1.0×104cells/L)。不同季节优势种有明显的交错和变化,菱形海线藻、奇异棍形藻、具槽帕拉藻为全年优势种。浮游植物物种多样性指数和均匀度都表现出较高的值,均匀度与多样性指数的季节变化特点基本一致,群落多样性高的季节物种均匀度也好。物种多样性指数指示调查区水体遭受污染程度低,水质状况优。调查区各季节的浮游植物丰度与温度之间无显著的相关关系,1月丰度与盐度则呈密切负相关关系。10月浮游植物丰度与无机氮(DIN)呈密切的正相关关系。7月浮游植物丰度与活性磷酸盐(PO4-P)呈密切的负相关关系。浮游动物对浮游植物的摄食压力直接影响到后者的丰度变动,并伴随着海区生态系统的相关复杂现象及生物学过程的作用。     

DISTRIBUTION,SEASONALITY AND REPRODUCTIVE PHENOLOGY OF BANGIA ATROPURPUREA (RHODOPHYTA) IN RHODE ISLAND,U.S.A.1

Forty-seven sites along the Rhode Island coastline were sampled on a seasonal basis for the presence of the red alga Bangia atropurpurea (Roth) C. Ag. This species was found to be widely distributed, occurring at 94% of the hard, stable substrates sampled. Bangia populations were most, widespread in the winter (71% of sites) and least frequent in the summer (29% of sites). At one location, three high intertidal populations (average height 101 cm) and three low intertidal populations (average height 14 cm) were sampled monthly for two years. The upper intertidal populations appeared in September and persisted until at least May, whereas the lower populations were ephemeral, appearing for only a few months in late winter. The high intertidal populations were present on 85% of the sampling dates white the lower ones were observed on 25% of the sampling dates. Upper intertidal filaments reproduced exclusively by asexual monospores unlike those of the lower populations which were largely sexual. The maximum diameter of asexual and carpogonial filaments was 120 and 250 nm, respectively. Monosporagenesis was strongly correlated to temperature whereas gametogenesis was strongly correlated to photopriod.     

金门岛北部海域浮游植物的季节变动及与环境的关联

采用2013—2014年四季度月在金门岛北部海域获取的浮游植物及环境因子监测数据, 分析该区浮游植物的群落结构和季节变化及其与温度、盐度、悬浮物、营养盐、叶绿素等的关系, 初步探讨涉海工程建设对浮游植物群落的潜在影响。结果显示, 鉴定出的浮游植物隶属3门43属82种(不含未定种), 群落构成以硅藻为主, 其次是甲藻, 蓝藻仅1种。物种组成的季节差异较大, 3月物种贫乏, 1月次之, 7月和11月最丰富。四季丰度平均为47.09×103 cells/L, 1月丰度最高, 7月次之, 11月最低, 3月高于11月少许。四季优势种均为硅藻, 13个优势种分别为柔弱几内亚藻(Guinardia delicatula)、短角弯角藻(Ecampia zoodicaus)、骨条藻(Skeletonema spp.)、具槽帕拉藻(Paralia sulcata)、微小海链藻(Thalassiosira exigua)、标志星杆藻(Asterionella notula)、旋链角毛藻(Chaetoceros curvisetus)、新月菱形藻(Nitzchia closterium)、派格棍形藻(Bacillaria paxillifera)、异常角毛藻(Chaetoceros abmormis)、小细柱藻(Leptocylindrus minutum)、宽角曲舟藻(Pleurosigma angulatum)和美丽曲舟藻(Pleurosigma formosum)。不同季节优势种有一定程度交错, 仅在单季占优的有6种, 有2/3在3个以上季节出现, 具槽帕拉藻、骨条藻为四季优势种。浮游植物物种多样性和均匀度总体较好, 群落结构稳定。与毗邻海区相比, 本区物种丰富度偏低, 丰度高于毗邻海区, 种类组成相似, 优势种却有较大差别。Pearson相关分析表明, 溶解无机氮及活性磷酸盐仅在1月与丰度存在极显著的正相关, 是促使丰度为四季最高的原因。涉海工程施工产生的悬浮物和冲击波是影响浮游植物群落的主要因素, 大量海洋工程建设案例表明, 施工期造成的浮游植物丰度下降趋势和优势种更替混乱在工程结束后能得以恢复。     

HETEROTROPHIC SLIMES IN FLOWING WATERS

1. While much attention has been paid to the ecology of macro-invertebrates in flowing water, the microbial ecology of such systems has been largely ignored and our knowledge of heterotrophic slimes in particular remains far from complete. Slime-forming organisms are ubiquitous in their distribution and are part of the normal riverine flora. Slime outbreaks occur in all types of organically enriched flowing fresh waters, regardless of their chemical nature. Slimes are predominantly of heterotrophs which require a constant supply of (i) a suitable carbon source, (ii) inorganic nutrients and in particular nitrogen and phosphorous, and possibly (iii) growth factors such as vitamins. Phosphorous is not a limiting factor for growth, with slimes developing in rivers with < 0·02 mg P l^-1. Other inorganic nutrients such as nitrogen can be used in various forms and are usually present in adequate amounts, even in unpolluted streams. Therefore occurrence appears to be most closely correlated with the presence of a source of available carbon. 2. The severity of outbreaks are not closely associated with soluble organic carbon content although there is a tendency for heavy growths to occur more frequently in more severely polluted waters. Low-molecular-weight sugars are clearly the causative agents of Sphaerotilus natans dominated slimes with higher molecular weight material such as starches not immediately effective as growth promoters. Mono- to penta-saccharides are mainly used by bacterial slimes while fungal components utilize fatty acids up to C₈. It is not possible to adopt a nationwide BOD₅ standards to control slime outbreaks as even small increases in river BOD₅ (< 1·0 mg l_-1) can support slime growth. There is a need to develop new methods of assessing the slime-promoting capability of effluents such as measuring the readily degradable low-molecular-weight carbon compounds, so that threshold concentrations of soluble organic carbon below which slime will not develop can be determined. 3. The effect of effluent enrichment on slime growth diminishes downstream as there is a tendency for the soluble carbohydrate to mix and dilute. The slime also metabolizes the carbohydrate, reducing the concentration by up to 60 % depending on the stage of slime development, thus limiting its own proliferation. This is the typical pattern of self-purification in flowing waters. 4. The taxonomy of all the slime-forming species are poorly understood as is the ecology of slimes. Species composition of slimes vary temporally and spatially within individual rivers. The primary factors affecting composition are nutrient type and water velocity, although pH determines whether a slime is either predominantly fungal or bacterial. The rate of transfer of oxygen and nutrients is dependent on water velocity with zoogloeal forms predominating as velocity falls to < 0·05 m s_-1. More details of the effects of water velocity and other environmental factors on all the slime-forming organisms is required. 5. The effects of specific environmental factors on slime growth have been determined primarily from laboratory-based studies, often using pure cultures on solid medium or batch culture methods. Clearly it has been difficult to relate these results to what is happening in the field. Little quantitative information on the productivity of slimes exist and the energy budgets or role of slimes in the self-purification process of rivers is largely unknown. The effects of temperature, pH, dissolved oxygen concentration, water velocity, solar energy input and grazing on the relationship between organic nutrient concentration and slime growth needs to be fully understood. Therefore there is a need for both field-based flow channel and field studies using mixed slime populations to accurately model the effects of environmental factors on slime development. Formation of such models is a prerequisite to the development of control strategies. 6. Due to slower oxidation rates at lower temperatures and reduced sloughing resulting in more luxuriant growths, slimes are generally considered to be more frequent and extensive in winter. However this is clearly not the case with outbreaks far more abundant in the summer due to the smaller flows reducing the dilution factor of effluents, and the enhanced temperature and suppressed oxygen concentration of the water, reducing competition and grazing. 7. The presence of slimes is not always detrimental, the major effect is unsightly appearance and reduced amenity value. Slime-forming organisms are predominantly aerobic and the rate of oxygen consumption of slimes is directly related to the dissolved oxygen concentration of the water. It would appear that slimes rarely cause deoxygenation, although sudden increases in water temperature which lowers the solubility of oxygen or enhanced chemical oxygen demand of the effluent due to reduced dilution, may cause total oxygen utilization. 8. The effects of slime growths on the aquatic environment are numerous and cumulative, especially in relation to salmonid fisheries. Nearly all pollutants that are released into the environment will enter surface waters at some stage, so the ability of heterotrophic slimes to rapidly accumulate heavy metals and perhaps other pollutants by various sorption processes will result in metals being concentrated and transferred along the food chain. This will eventually result in increased residual metal concentrations in fish or toxic concentrations of metals being accumulated in macro-invertebrates normally eaten by fish. Metals can be transported out of the polluted zone via sloughed floes and be released back in to solution downstream of the site originally affected. 9. The severity of problems associated with outbreaks increase with the length of the slime growth, with the majority of the longer outbreaks (> 5 km) resulting in oxygen depletion, increased siltation, alteration in flow pattern, increase in sloughed biomass, reduction in species diversity, destruction and reduction in habitat diversity and the elimination of fisheries. Case studies on the effects of slime growth, especially those causing fish kills, need to be carefully analysed and published. 10. The potential of heterotrophic slimes in biotechnology and wastewater treatment has yet to be fully realized. The ability to grow rapidly, producing considerable biomass rich in protein could be utilized. The sorption of heavy metals by all the slime-forming organisms but especially by the iron and manganese bacteria, could be used for the removal of low concentrations of metals in wastes, treatment of metal-rich effluents or for metal recovery. The property of removing phosphorous and nitrogen from solution should also be further considered. 11. No adequate control measures are available except for full treatment of effluents prior to discharge. Even traces of low-molecular-weight carbon compounds will result in slime development. Inadequate partial treatment may enhance slime growth by partially breaking down the effluent and releasing slime-promoting compounds. Intermittent discharge can reduce the standing crop of slime per unit surface area but as the total biomass supported by an effluent will remain the same, the slime will be extended over a greater length of river. Bacterial slimes are assemblages of filamentous and dispersed bacteria, and are far more common than fungal or algal dominated slimes. The two slime-forming organisms S. natans and zoogloeal bacteria are the major components of the majority of heterotrophic slimes, therefore any attempt at control should be aimed at these two species.     

WHALE REACTIONS TO HUMAN ACTIVITIES IN CAPE COD WATERS

A review of our whale observations of more than 25 years indicated that each of the species commonly observed within 35 km of Cape Cod reacted differently to stimuli from human activities, and that these responses have gradually changed with time. Over the years of exposure to ships, for example, minke whales ( Balaenoptera acutorostrata ) have changed from frequent positive interest to generally uninterested reactions, finback whales ( B. physalus ) have changed from mostly negative to uninterested reactions, right whales ( Eubalaena glacialis ) have apparently continued the same variety of responses with little change, and humpbacks ( Megaptera novaeangliae ) have dramatically changed from mixed responses that were often negative to often strongly positive reactions. These reactions appeared to result mostly from three types of stimuli: primarily underwater sound, then light reflectivity, and tactile sensation. The whale reactions were related to their assessment of the stimuli as attractive, uninteresting or disturbing, their assessment of the movements of the sources of the stimuli relative to their own positions, and their assessment of the occurrence of stimuli as expected or unexpected. Whale reactions were modified by their previous experience and current activity: habituation often occurred rapidly, attention to other stimuli or preoccupation with other activities sometimes overcame their interest or wariness of stimuli, and inactivity seemed to allow whales to notice and react to stimuli that otherwise might have been ignored. The changes over time in the reactions of whales to stimuli from human activities were gradual and constantly varying with increased exposure to these activities.     

第四纪沟鞭藻类在海南岛砂质白云岩中的发现

该文所研究的样品采自海南省儋县排浦乡,为一套珊瑚岸礁海蚀坪潮间带的更新世砂质白云岩。作者对其中两块样品进行了分析研究,并获得沟鞭藻类囊孢4属10种,其中包括1新种2未定种。文中除了对这些属种进行了较为详细的描述以外,还讨论了它们所反映的古环境,认为含有这些化石的砂质白云岩是暖温带浅海环境下的产物。