Search

A new technique for the establishment of a permanent laboratory culture of Chironomus riparius is described. Larvae and pupae were reared in plastic tanks containing tap water, filamentous algae and a commercially prepared fishfood. The tanks were aerated, maintained at a constant temperature of 24°C and subjected to a constant lighting regime of 13 h of light followed by 11 h of darkness. Adults flew freely in a modified handling box, mated, and oviposited on strips of filter paper placed in the plastic tanks containing the aquatic stages. It has proved unnecessary to change the water or medium, which has saved both time and effort. Moreover, larvae established themselves in ail parts of the alga, and therefore more could be kept in each tank than when, as in previous methods, they are provided only with a substratum on the floor of the container. [ABSTRACT FROM AUTHOR]

The article presents a study about a multivariate approaches to the ecology of algae on terrestrial rock surfaces in North Wales. This paper focused on the quantitative and qualitative data collected from two restricted areas which looked into the ecology of terrestrial algae. A review of the epilithic algae is included providing the phytosociological information on the algae. Subjective classifications were done on algae communities. The present study involved modern techniques of investigation using multivariate analysis of tropical freshwater algae.

The article discusses the study regarding the distribution of the Bacillariophyceae algae living on the sediments of some lakes of the English Lake District. The author mentions that the study measures the seasonal change in total diatom population and in certain genera by obtaining the summation of the counts of cell numbers of all species and other individual genera. The study confirms the reports of earlier papers that the benthic epipelic diatom community goes through distinct seasonal changes including low winter growth, high spring growth, and moderate autumn growth.

During hydrobiological investigations on the River Oshun, plankton samples were taken with a hand net of fine mesh for 14 months (May 1968–June 1969). Thirty-seven of the sixty species of algae identified have not been previously recorded in Nigeria. The qualitative character of the Oshun algae indicates the dominating nature of the floods in mixing bottom-living and rock-dwelling algae with the few euplanktonic species. [ABSTRACT FROM AUTHOR]

The theory that Skeletonema cells adapt to lower temperatures by increasing their enzyme concentration, is supported by various facts. While the rates of photo- synthesis are identical in cells adapted to different temperatures (7-20°C) the growth rate decreases with decreasing temperature and the production of organic matter increases with decreasing temperature. Further, the concentration of protein per cell and the height of the cells increase with decreasing temperature. [ABSTRACT FROM AUTHOR]

The article presents information on bound ornithine in certain flexibac teria and algae. Free ornithine is found in aqueous extracts of nearly all plant and animal tissues. It is assumed to he mainly an intermediate in the synthesis of citrulline and arginine. Although ornithine has never been found as a constituent of cellular proteins, it exists in a bound form in several cyclic polypeptide antibiotics isolated from bacteria.

The article presents abstracts of articles related to vegetation and ecology which include "Some Freshwater Algae of Southern Quebec," by C. W. Lowe, "A Bio-Hydrographical Investigation of the Sea Adjacent to the Fraser River Mouth," by C. C. Lucas and "Axyris amarantoides in Eastern America," by M. L. Fernald .

Calorific values of thirty-three species of aquatic invertebrates, representing various life stages, from small prairie wetlands are given. The values for twenty-seven species are new to the literature. Percentage crude protein for fifteen species and the amino acid composition for eleven taxa are presented. The majority of the species dealt with are eaten by waterfowl. [ABSTRACT FROM AUTHOR]

Light-stimulated active chloride influx in Chara corallina, like that in other giant algal cells, requires the operation of photo-system two of photosynthesis. Active phosphate influx and glucose influx also require photo-system two for light-stimulation, and are not stimulated by light under anaerobic conditions. This contrasts with the situation in Nitella and Hydrodictyon where influx of phosphate and glucose can be supported by photo-system one, i.e. by cyclic photophosphorylation alone. None of the other metabolic processes in Chara tested in this work (acetate uptake and oxidation, starch synthesis, and passive Rb+ influx), or described elsewhere in the literature, are light-stimulated when photo-system two is inoperative. Possible explanations of this apparent inability of cyclic photophosphorylation to act as a source of metabolic energy in Chara are suggested. Their significance is discussed in relation to hypotheses of the light reactions of photosynthesis and mechanisms of light-dependent solute transport. [ABSTRACT FROM AUTHOR]

The United States government has advanced a proposal for a ‘species’ approach to the resolution of problems in the management and distribution of living marine resources. Under this approach, the management and distribution of the stocks of coastal species of fish would be handled by negotiation among interested parties on a stock-by-stock basis, with certain preferential rights accorded to the coastal state. This approach is now being tested in the developments taking place in the arrangements for the Northwest Atlantic fisheries. Here, 15 nations agreed to divide up among themselves the annual yields of 14 separate stocks of fish. In addition, it has now been proposed that there be a limit on the total amount of fishing effort and a division of the total among states. The controls are based solely on the physical attributes of fishing and fail to take account of economic consequences. Because of this, questions can be raised about the viability of the arrangements and of the ‘species’ approach to the international law of fisheries. [ABSTRACT FROM AUTHOR]

The kinetics of the inhibition of photophosphorylation in chloroplasts from spinach (Spinacia oleracea) was investigated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) in small concentration intervals, starting at 10-7 M. Plots of the reciprocal of photophosphorylation against concentration of DCMU gave essentially the same straight line with 2 mM nicotinamide adenine dinucleotide phosphate (NADP) together with saturating amounts of ferredoxin or with 4 mM K3Fe(CN)6 as the final acceptors for electrons. Practically complete inhibition was obtained at 3 × 10-6 M DCMU. With 0.1 mM flavin mononucleotide (FMN) and ferredoxin, the inhibition between 10-7 M and 10-6 MDCMU was a little slower than in the other two cases. At 10-6 M DCMU a break occurred to a new straight line in the plots, indicating that another reaction was inhibited. Total photophosphorylation without DCMU was about 77 μmol ATP per mg chlorophyll and hour. At the breaking point 20 % remained, and inhibition was not complete even at 8 × 10-6 MDCMU. The inhibitor constant for the high-DCMU reaction was in the order of 2 × 10-5 M; for the low-DCMU reaction some complication made the "constant" appear negative. With phenazine methosulfate (PMS) added, DCMU was without effect on photophosphorylation. - As earlier shown by us, titration curves for intact cells of the microalga Scenedesmus show the break at 1010-6 M DCMU; and above 6 × 10-6 M photophosphorylation in the algae is not further decreased by DCMU. The data are compared and their possible significance is discussed. [ABSTRACT FROM AUTHOR]

The effects of abscisic acid, salicylic acid and trans-cinnamic acid were tested on the light-induced phosphorylating reactions and oxygen evolution of the unicellular green alga Scenedesmus. It was found that abscisic acid and cinnamic acid had practically no influences on the total inorganic phosphate uptake, while salicylic acid in the concentration range of 10-6 to 10-3 M gave a small decrease in the total inorganic phosphate uptake. The ATP level in the cells is in most cases increased when these three acids are given to the algae. The oxygen output is not significantly changed by abscisic acid or salicylic acid. Trans-cinnamic acid inhibits the oxygen evolution at concentrations of 10-4-10-3 M. None of the substances investigated caused such effects on photophosphorylation and oxygen evolution in Scenedesmus as those caused by the inhibitor β-complex from potatoes according to earlier reports. It is suggested that those effects are due to other components in the inhibitor β-complex. [ABSTRACT FROM AUTHOR]

A survey of the adaptation of plankton algae in Nature to different light intensities and temperatures is given. The adaptation is always important for the plankton populations at all depths. However, the shade adaptation of the algae in the lower part of the photic zone is often of relatively little importance for the integral primary production per unit of surface, except on the by no means rare occasions when the hulk of the algae is found in this lower part. It is shown that the Ik of surface plankton during summer in the Arctic is high despite the low temperatures present. This is due to an increase of the enzyme quantities per cell. Daily fluctuations in Ik are due partly to photooxidation, partly to the fact that the periods for the production of chlorophyll and photosynthetic enzymes are mutually displaced. Despite the daily fluctuations in Ik the difference between "sun" phytoplankton and "shade" phytoplankton is distinct. [ABSTRACT FROM AUTHOR]

Two quantitative methods have been devised for studying the phototactic response of Chlamydomonas. In the first procedure, the movement of a cell population is continuously monitored photometrically, yielding a permanent record of the time course of the response. The monitoring system consists of a pair of photovoltaic cells connected in a comparison circuit, and a dim red light which passes through the swimming chamber and strikes the photocells. A stimulus beam enters the chamber at right angles to the monitoring light. The movement of algae towards the stimulus light produces a difference in output between the photocells. With a continuous stimulus, this difference increases in a nearly linear fashion for several minutes. The slope of the linear portion depends on such factors as stimulus intensity and wavelength and is used as the index of the response. In the second procedure, a photomicrographic method is used to resolve the population response into its components; i.e., the number of cells responding, the directness of the swimming path, and the rate of swimming. The photographs are taken with a fixed exposure time, during which each cell in the field describes a swimming track on the film. Swimming rate is determined by measuring the length of the photographed track, while directness of path is indicated by the angle between the track and the stimulus light beam. The number of cells going towards the light is calculated from counts made while observing the culture through the microscope. These methods have been used to investigate the dependence of phototaxis on stimulus intensity and wavelength, age of culture, and pre-illumination. [ABSTRACT FROM AUTHOR]

A description is given of an apparatus for semi-continuous cultivation of unicellular algae under various combinations of light intensity, temperature and daylength (photoperiod). In this apparatus growth of the coccolithophorid Coccolithus huxleyi was limited by light intensities below 0.05 cal/cm² · min regardless of daylength. Growth was retarded by daylengths shorter than 16 hours out of a total of 24 hours of light plus dark. The temperature optimum for growth was about 20 C and showed little variation with daylength. The content of chlorophyll a varied between 2 and 15 mg per ml cell volume and was greatest under low light intensities, short daylengths and high temperatures. Cultures were synchronised by four different combinations of light intensity and daylength. In all four cases, cell division was restricted to 6 out of 24 hours. Synchronised cell division took place in the dark but its timing bore no simple relationship to the onset or termination of illumination. [ABSTRACT FROM AUTHOR]

Some red algae in axenic culture have been cultivated with different additions of iodine and bromine. Polysiphonia urceolata appeared to have an absolute demand for iodine. Additions could be made either as organically bound iodine or as inorganic Iodine. A linear correlation between amount of added iodide and growth was found for iodide concentrations from 1 μmol up to at least 8 μmol per 1. Nemalion proved to be indifferent to iodide additions, white Goniotrichum elegans was inhibited by concentrations higher than 0.4 μmol per 1, which corresponds to that of natural seawater. High additions of iodine generally inhibited growth of nonaxenic algae. Acrochaetium made an exception, being stimulated by 4 μmol per 1. Bromine in the same concentration as that of seawater, viz. 814.3 μmol per 1 inhibited growth of most species, but amounts smaller than 50 μmol had in some experiments a slightly increasing effect. Bromine seems, however, not to play an essential part in the metabolism of Polysiphonia urceolata. [ABSTRACT FROM AUTHOR]

The influence of oxygen concentration in the range 0-21 % on photosynthesis in intact leaves of a number of higher plants has been investigated. Photosynthetic Co2 fixation of higher plants is markedly inhibited by oxygen in concentrations down to less than 2%. The inhibition increases with oxygen concentration and is about 30% in an atmosphere of 21% O2 and 0.03 % CO2. Undoubtedly, therefore, oxygen in normal air exerts a strong inhibitory effect on photosynthetic CO2 fixation of land plants under natural conditions. The inhibitory effect of oxygen is rapidly produced and fully reversible. The degree of inhibition is independent of light intensity. The quantum yield for CO2 fixation, i.e. the slope of the linear part of the curve for CO2 uptake versus absorbed quanta, is inhibited to the same degree us the light saturated rate at all oxygen concentrations studied. Diverse species of higher plants, varying greatly in photosynthetic response to light intensity and CO2, concentration, and with light saturated rates of CO2 fixation differing by a factor of more than 10 times, show a remarkable similarity in their response to oxygen concentration. By contrast, when studied under the same conditions as the higher plants, the green algae Chlorella and Ulva did not show any measurable inhibition of photosynthetic CO2 fixation. Similarily, the increase in fluorescence intensity with increasing oxygen concentrations found in higher plants also was not seen in Chlorella. The Present results, together with previous data on the photosynthetic response of algae to oxygen concentration, indicate that the photosynthetic apparatus of higher plants differs considerable from that of algae in its sensitivity to oxygen. The inhibitory effect of oxygen on photosynthetic CO2 fixation in higher plants is somewhat higher at wavelengths which excite preferentially photosystem I. Also, the Emerson enhancement of CO2 fixation measured when a far red beam of low, intensity is imposed on a background of red light is greater under low oxygen concentration that under air. Measurements of reversible light-induced absorbance changes reveal that the change at 591 nm, probably caused by plastocyanin, is affected by oxygen concentration only if photosystem II is excited. The reducing effect on plastocynin, caused by excitation of this system, decreases with increasing oxygen concentration. From these results it is suggested that a possible site of the inhibition by oxygen is in the electron carrier chain between the two photosystems. Oxygen might act as an electron acceptor at this site, causing reducing power to react back with molecular oxygen. However, this hypothesis does not account for equal inhibitions of the quantum yield and light saturated rate of photosynthetic CO2 uptake. [ABSTRACT FROM AUTHOR]

A study has been made of the occurrence of the three types of induction curves (CO2-time curves), i.e., the primary-peak curve, the light-gush curve, and the half-arch curve, in 8 species of red algae, 5 species of brown algae and 6 species of green algae. The results are reviewed in Table 1. The primary-peak type of curve dominates among the red algae as well as among the cormophytes. Both primary-peak curves and light-gush curves are found among the brown and the green algae: the light-gush type occurs most frequently. A small number of half-arch curves are found within all of the taxonomic groups studied. In the case of Chlorella the light-gush curves appear only when the cells are grown in a medium enriched in carbon dioxide (air containing 3 to 5 % CO2 is bubbled through the nutrient solution) and when the determinations of the carbon dioxide exchange are made in air rich in carbon dioxide. Other species of green algae show light-gush curves when grown in media in equilibrium with the carbon dioxide content of ordinary atmospheric air, as do some of the species of brown algae included in the present study. The CO2-acceptor systems responsible for the formation of the various types of induction curves are discussed. [ABSTRACT FROM AUTHOR]

The inhibition of the photosynthesis of Scenedesmus qnadricauda by KCN at various pH values and at various concentrations of CO2 has been studied. When the CO2 concentration exceeds 500 μM, the inhibition by 10 μM KCN is very low. At limiting concentrations (100-200 μM), the inhibition of CO2 assimilation is more pronounced. This inhibition seems to be competitive. At high pH values, the inhibition is strong which may be explained either by assuming a continuation of the competitive inhibition of the CO2 assimilation or as an incompetitive inhibition of HCO3- which is present in a great surplus. [ABSTRACT FROM AUTHOR]

The effect of cyanide and azide on respiration and nitrate absorption in the green algae Scenedesmus quadricauda and Chlorella pyrenoidosa has been examined. The respiration of Scenedesmus is not sensitive to cyanide (previous results), whereas the respiration of chlorella is inhibited to 50 per cent by 50 μM HCN. The sensitivity of nitrate absorption to cyanide is about the same in the two algae, Scenedesmus being inhibited to 50 per cent by 3 μM (previous results) and Chlorella by 10 μM. Azide has the same influence on both Scenedesmus and Chlorella. Respiration is slightly stimulated by 3 μM HN3 and inhibited to 50 per cent by 30 μM HN3. Nitrate absorption is inhibited to 50 % by 0.2 μM HN3. [ABSTRACT FROM AUTHOR]

The seasonal periodicity of four species of planktonic diatoms in a small eutrophic lake in the Shropshire-Cheshire Plain, England, is examined. Diatoms typically dominate the spring increase; a second period of growth follows in the summer months. The growth phases are considered in relation to environmental factors in the mere. Of these, light levels appear to be critical in determining the onset of growth and the size of the population maxima, whilst stratification and turbulence play a leading role in the vertical distribution of the algae, and hence, of the growth conditions to which they are exposed. The thermocline is believed to provide a reservoir of diatoms in summer, maintaining them in a position where they are able to gain maximum advantage from increased wind-induced turbulence. Relative specific differences in growth requirements and in behaviour under varying physical conditions are important in determining which species dominate. Dominance may be modified by the effect of attacks by fungal parasites. It is also shown that, generally, nutrients are present in relative abundance, and only rarely does their availability become a limiting factor. It is concluded that diatom growth in this lake is typically subject to physical rather than chemical control. [ABSTRACT FROM AUTHOR]

The article discusses the new and more specific information regarding the importance of aquatic and semi-aquatic insects in the passive dispersal of micro-organisms with particular focus to the Odonata associated with aquatic habitats near the University of Oklahoma Biological Station where the laboratory facilities are provided. It is suggested that insects were collected and transferred into an autoclaved vials measuring 32-ml that contains 16-ml of sterile oil water extract. It is inferred that the cultured washings were examined using a microscope twice or thrice for 5 months while vials are sampled with sterile pipettes and the organisms are identified and recorded.

The article reports on the methods for estimating populations of attached algae, particularly diatoms on rock and bryophytes in a stream and other algae in small stony stream. It states that populations at eleven stations in small stony stream were followed by periodic sampling for four years. The sampling includes standard chemical analyses; temperature measurements at the sampling stations; total light in the open; daily rainfall records; the approximate shading at each station; and comparisons of the fauna at two stones stations. The author details the distribution and the factors controlling the periodicity of Achnanthes species group.

The article reports on a two-year study of the ability of algae to survive in dry conditions. The data gathered for the study included the water's levels, temperatures and pH levels, and the mud and litter's moisture and organic content. Through culturing and observation, it was found that certain algae survived lengthy exposure through cell wall thickening, a gelatinous covering, and the cell's accumulation of oil. The test also revealed that the vegetative stages' ability to resist exposure and drying is the major controlling factor of algal zonation..

The article discusses the free-living forms of Ascophyllum nodosum. It provides the classification of forms and the key for determining their identity. There are five distinct forms of Ascophyllum nodosum namely ecad mackaii or beach form, ecad mackaii or turf form, ecad scorpioides or Baltic form, ecad scorpioides or marsh form and variety minor. A highlight on the ecad mackaii or beach form is presented, which discusses the factors controlling its occurrence and developments and the different methods of development.

The article reports on Tarn Moor as a highland area of preserved wetlands, common moorland in central Westmorland and it overlies limestone rock and comprises many springs. It discusses that the upper regions of the moor are prevailed by Calluna vulgaris, and the holes hold cryptic humate and mires of numerous kinds. Along the sides of the valleys there is a broke belt of 'wet flush' vegetation overlaying a shallow peat or mineral soil. Many of the springs emerge in this zone. An overview on Tarn Moor is presented.

The article reports on Tarn Moor as a highland area of preserved wetlands, common moorland in central Westmorland and it overlies limestone rock and comprises many springs. It discusses that the upper regions of the moor are prevailed by Calluna vulgaris, and the holes hold cryptic humate and mires of numerous kinds. Along the sides of the valleys there is a broke belt of 'wet flush' vegetation overlaying a shallow peat or mineral soil. Many of the springs emerge in this zone. An overview on Tarn Moor is presented.

The article reports on Tarn Moor as a highland area of preserved wetlands, common moorland in central Westmorland and it overlies limestone rock and comprises many springs. It discusses that the upper regions of the moor are prevailed by Calluna vulgaris, and the holes hold cryptic humate and mires of numerous kinds. Along the sides of the valleys there is a broke belt of 'wet flush' vegetation overlaying a shallow peat or mineral soil. Many of the springs emerge in this zone. An overview on Tarn Moor is presented.

The article reports on Tarn Moor as a highland area of preserved wetlands, common moorland in central Westmorland and it overlies limestone rock and comprises many springs. It discusses that the upper regions of the moor are prevailed by Calluna vulgaris, and the holes hold cryptic humate and mires of numerous kinds. Along the sides of the valleys there is a broke belt of 'wet flush' vegetation overlaying a shallow peat or mineral soil. Many of the springs emerge in this zone. An overview on Tarn Moor is presented.

The article reports on Tarn Moor as a highland area of preserved wetlands, common moorland in central Westmorland and it overlies limestone rock and comprises many springs. It discusses that the upper regions of the moor are prevailed by Calluna vulgaris, and the holes hold cryptic humate and mires of numerous kinds. Along the sides of the valleys there is a broke belt of 'wet flush' vegetation overlaying a shallow peat or mineral soil. Many of the springs emerge in this zone. The discussion on Tarn Moor is also presented.

The article discusses the algal survey of extensive coastal areas in Scotland, which intends to determine the distribution and relative quantity of the commoner species of Fucaceae. The Fucoid algae which are found most abundant are Pelvetia canaliculata, Fucus spiralis, F. vesiculosus, Ascophyllum nodosum, A. nodosum var. mackaii and Fucus serratus. It is noted that horizontal distribution of these algae is very irregular and individual species differs in the extent of their distribution. The nature of the substratum, degree of exposure to wave action and angle of slope of the shore are the main factors controlling horizontal distribution.

The article presents the scientific study assessing the habitat and survival of sessile algae in organically enriched river water. It discusses the characteristic of algae and how its growing ability increases with the decomposition of organic matters in the river water. Accordingly, the research method uses refortification process and has discovered several communities of algae in different zones in the rivers. Several Algae that have been discovered were the Stigeoclonion tenue at the polysaprobic zone, Nitzchia palea and Gomphonema parvulum at mesosaoprobic zone and Cocconies placentula-Chaesmaessiphon species and Ulvella frequens at oligosoprobic zone.

The article reports on the study of the effects of mineral composition namely nitrogen and phosphorus concentrations on the growth of plankton algae such as Pediastrum boryanum and Staurastrum paradoxum. The study uses mineral concentrations which were found in natural waters to examine the occurrence of planktonic organisms. It shows that concentrations of nitrogen and phosphorus for the growth of plankton organisms are higher in freshwaters than in natural waters. It also demonstrated that nitrogen in the form of ammonia can be used by algae in their growth.

The article discusses a research, which was aimed at discovering whether there was a definite community of unattached algae living on the bottom deposits of ponds and to determine the influence of these deposits on the littoral algae. The study was conducted in England in January 1936 until March 1938. The results showed that the bottom deposits in the littoral regions of ponds bear a growth of algae on or in close proximity to the surface. Occasional observations on the littoral regions of other ponds revealed that similar floras are of widespread occurrence.

The article presents a study that investigates the ecology of river as well as the growth and distribution of sessile algae at the River Hull in England. The study was administered by collecting the different types of algae that grows in the calcareous and non-calcareous areas within the river for more than two and a half years and its data were analyzed using qualitative observation. The study reveals that algae in calcareous water recorded the highest prevalence of growth wherein Cocconeis placentula and Ulvella frquens are dominant within the community wherein bountiful supply of nitrates and mineral salts are also present.

The article reports on the ecological and taxonomic investigation of the littoral algal flora of Lake Windermere. Lake Windermere is one of the lakes that has been described as approaching the geomorphic oligotrophic type of Donat. The research showed that the distribution of the littoral algae has been found to depend on water depth, light intensity, and factors associated with the habitat. The results obtained were divided into three categories: ecological factors, periodicity and origin of plankton algae. A table on the distribution of macrophytes and other substrata examined in Lakes Windermere and Derwentwater is also presented.

The article reports on the ecological study of the algae living on the British Chalk-Cliffs. The growth of the algal on the surface of the cliffs forms four distinct horizontal belts, which extend for long distances and are interrupted only by caves and stone embankments. These belts are the Fucus belt, Enteromorpha belt, Chrysophyceae belt, and Endoderma belt. The distribution of the algae on the face of the cliff is influenced by factors such as the amount of water, the salt concentration and the temperature. The belts have algal vegetation, which can be grouped into a number of communities whose distribution is related to their position with respect to high tide level, to the degree of illumination and to the nature of the substratum.

The article presents study on the preliminary account of vegetation in the River Itchen near Cheriton in Kent, South of England. The general survey of the vegetation was first observed by the Ministry of Agriculture and Fisheries Freshwater Station as preliminary to the full biological survey of the river system. This project aims to record the biological conditions of unpolluted rivers. These were compared with the biological conditions of polluted rivers. Organisms are noted and compared, ecological conditions, phytoplanktons and algal vegetation were also reviewed. This study is part of a program that focused on the ecology of smaller streams which were not as popular as the studies devised for bigger rivers.

Eighteen surface water samples were collected during 1970 from Lake Mälaren (freshwater) and to the outer part of the Stockholm Archipelago (brackish water). After filtration most samples were enriched with phosphate (P), nitrate (N) and chelated trace elements (TE), alone or in combination, and inoculated with blue-green algae, Oscillatoria Agardhii or Aphanizomenon flos-aquae, isolated from the investigated area. The algae (not free from bacteria) were cultivated under standard conditions. The dry weight at harvesting was used to evaluate the growth-stimulating effect (in comparison with unenriched controls) of the additions. The yields of O. Agardhii (the controls and those with all three additions) were largest 17–26 km to the east of Slussen, the Stockholm lock. During the year the smallest growth occurred during summer. The results with A. flos-aquae followed a similar distribution pattern. Regression analysis of the results with O. Agardhii showed that enrichment with TE or P, alone or together, did not stimulate growth. The addition of N, alone and in combinations with TE or P, stimulated the growth, in proportion to the growth in the unenriched water samples. The enrichment with P + N + TE gave the largest stimulation. [ABSTRACT FROM AUTHOR]

Mississippi River alluviation has provided Louisiana with a deltaic coast which contrasts sharply with the remainder of the Gulf littoral. Salient differences lie in coast configuration, hydrographic patterns, water chemistry, sediments, and vegetation. Although the species of marine life are largely the same here as elsewhere in the Gulf area, their ecology is closely governed by and geared to the highly fluctuating deltaic environment. The mud bottoms, decaying marsh grass, and nutrients provided by the Mississippi River are especially favorable for an abundant shellfish population. The very productive fisheries of Louisiana are largely concerned with shellfish production and such plankton feeders as menhaden. The fisheries are concentrated in those coastal areas most actively influenced by the Mississippi drainage.

The article offers information on marine fishery resources in the vicinity of Amchitka Island in Alaska. It states that commercial fishery resources in the Amchitka region are utilized by United States, Soviet, and Japanese fishermen. Fishing surveys conducted by the Fisheries Research Institute of the University of Washington during the AEC-sponsored program have not manifested any large stocks of commercially essential fish or shellfish close to Amchitka, except possibly salmon at certain periods of the year. Accompanying photographs and graphical representation of the research are also presented.

The article presents information on the prospects of aquaculture in the U.S. with reference to the work "The Status and Potential of Aquaculture," by John H. Ryther and John E. Bardach. It is stated that a great deal is known about the genetics of beef cattle, wheat, and corn but very little is known about the genetics of fish, molluscs, crustaceans, and marine algae. It also mentions that the U.S. has overlooked potential productivity of aquaculture for its preoccupation with land-based crops. The authors mention in their work that while intensive pig farming in developed nations leads to a production of around 25 tons of live pigs per man-year, oyster farmers can raise 40-60 tons of oysters per year.