Showing papers in "Hydrobiologia in 1980"
TL;DR: The water, fat, protein and energy contents of young salmon from a stream in Scotland indicated that nutritional insufficiency may be an important factor in determining their survival pattern over the first year of life.
Abstract: The causes of mortality of young fish in streams are not well understood. The water, fat, protein and energy contents of young salmon from a stream in Scotland indicated that nutritional insufficiency may be an important factor in determining their survival pattern over the first year of life.
154 citations
TL;DR: Snails were very efficient at clearing smooth surfaces of living cells, detritus, and particulate inorganic matter and little evidence of selectivity except for an apparent inability to remove some of the smallest cells (e.g. Cocconeis sp.) probably for mechanical reasons.
Abstract: Qualitative and quantitative measures of the Aufwuchs (scum flora) on artificial substrates in situ were used to evaluate the effects of grazing by freshwater pulmonate snails in a shallow pond in southeastern Michigan. Grazer densities of ∼ 216 snails/m2 marked reduced standing crop so that after 45 days grazed substrata had 6.46 mg dry weight, 604 µg C and 4.18 µg chlorophyll a as compared to controls with 30.62 mg dry weight, 3699 µg C and 6.29 µg chlorophyll a, all on a per dm2 basis.
130 citations
TL;DR: In this article, the impact of the fish population on trophic properties of lake water, was experimentally studied in an oligotrophic Swedish forest lake, and the results showed that fish removal resulted in a development in a more stable and stable direction, as shown by the drop in primary production, pH, total phosphorus, total nitrogen and increased transparency.
Abstract: The impact of the fish population on trophic properties of lake water, was experimentally studied in an oligotrophic Swedish forest lake. Biotic changes following fish removal resulted in a development in oligotrophic direction as shown by the drop in limnetic primary production, pH, total phosphorus, total nitrogen and the increased transparency.
126 citations
TL;DR: There can be no question but that the feeding biology of free-swimming, suspension-feeding rotifers is a rich and exciting field for freshwater ecologists and natural historians.
Abstract: While the evidence is not yet adequate to provide a general assessment of rotifer feeding in the dynamics of planktonic communities, there can be no question but that the feeding biology of this group is a rich and exciting field for freshwater ecologists and natural historians. Two recent reviews, those of Dumont (1977) and Pourriot (1977), provide ample evidence for this assertion, together summarizing some 70 years of research on rotifer feeding behavior. This paper is a further discussion of certain aspects of the feeding behavior and feeding ecology of free-swimming, suspension-feeding rotifers. I will deliberately omit consideration of sessile or predacious genera since the feeding biology of these forms has been reviewed very recently; sessile rotifers are examined by Wallace (1980) and the predacious genus Asplanchna by Gilbert (1979).
125 citations
TL;DR: Two readily distinguishable species of Chydorus sphaericus sens. str.
Abstract: Two readily distinguishable species of Chydorus sphaericus sens. lat. occur in Salmon Lake, Montana, differing from each other in size and shape of rostrum, headpore configuration, frequency of doubling of teeth on the postabdomen, pattern of reticulation of the shell, and morphology of the mature male, especially the postabdomen, postabdominal claws, copulatory hooks, and rostrum. In any such comparisons, individual specimens are not sufficient; populations are needed to sort out morphological characters associated with instar and sex and character's that change with increasing body size. Comparison of population structure and stage of reproduction can be accomplished by a size-frequency distribution and by specific morphological characters that enable the three male instars to be recognized individually. One species, thought at first to be Chydorus herrmanni, is very close to Chydorus sphaericus sens. str. from Denmark. The other taxon with a short, generally blunt labrum, is described as the new species Chydorus brevilabris. Because of morphological diversity among the entities currently listed as Chydorus sphaericus from around the World, it is certain that a complex of species is represented. To facilitate the eventual resolution of this problem, the population in Sjaelso, Sjaelland, Denmark has arbitrarily been selected as the standard of comparison, and from this population a neotype and several allotypes have been designated. Cursory examination of various available populations suggests that C. sphaericus sens. str. and C. brevilabris represent a major dichotomy in the sphaericus complex, each branch consisting of an unknown number of closely-related species. Cautions are voiced against assuming that Chydorus sphaericus is a single cosmopolitan and ubiquitous species.
110 citations
TL;DR: In this paper, the lakes in the lower Siwalik Himalayas, five in the Kashmir valley and two situated in the high mountains of the Kashmir Himalaysas were investigated for their physico-chemical and biological features.
Abstract: Two lakes in the lower Siwalik Himalayas, five in the Kashmir valley and two situated in the high mountains of the Kashmir Himalayas were investigated for their physico-chemical and biological features. The lakes, differing significantly in their morphology and in thermal behaviour, rank from the subtropical monomictic to the dimictic type. The lakes at high altitudes (> 3000 m) have very low electric conductivity which increases with the decrease in altitude. The most dominant ions in water are calcium and bicarbonate. The macrophytic vegetation of the lakes does not show any definite relationship either with altitude or with physico-chemical milieu. In the lakes with low fertility the phytoplankton is dominated by diatoms and Chlorophyceae but in eutrophic lakes Cyanophyceae predominate. The zooplankton population of the lakes is mainly comprised of rotifera. On the basis of general limnological features and the rates of phytoplankton production most of the lakes may be categorized either as eutrophic or in the process of rapid evolution. Only one lake is oligotrophic.
107 citations
TL;DR: In this paper, periphytic diatom communities on clay tile and sterilized rock substrates were compared with those on natural substrates, and the advantages of utilizing introduced substrate communities and problems encountered with their simulation of the natural substrate community were discussed.
Abstract: Periphytic diatom communities on clay tile and sterilized rock substrates were compared with those on natural substrates. Clay tiles yielded diatom communities with the least variability between replicate samples, and the greatest similarity to the natural substrate assemblage. The advantages of utilizing introduced substrate communities and problems encountered with their simulation of the natural substrate community are discussed.
106 citations
TL;DR: An account is given of the development of the utilization of microalgae for food and feed with special emphasis on the advantages of algal technologies for tropical and subtropical countries.
Abstract: An account is given of the development of the utilization of microalgae for food and feed with special emphasis on the advantages of algal technologies for tropical and subtropical countries. The present status of microalgae mass production is characterized with respect to technology, product properties, yields, nutrition, toxicology and economics. As a multipurpose operation, the treatment of liquid wastes with algae-bacteria systems is the most promising microalgal technology. It yields proteinaceous microbial biomass as a comparatively inexpensive by-product of the operation of high-rate algal ponds, either at the simplified rural level or at the technically more elaborate industrial level. The aspect of hard-currency saving by employing algae-bacteria systems in sewage treatment for animal feed production is stressed.
103 citations
TL;DR: A preliminary survey of the benthic fauna of sites on the Nent system affected by elevated zinc levels, acid water and organic enrichment is described, and Chandler biotic scores were found to be lowest at sites affected by high zinc levels and/or dense growths of the alga Stigeoclonium tenue.
Abstract: A preliminary survey of the benthic fauna of sites on the Nent system affected by elevated zinc levels, acid water and organic enrichment is described. Data on faunal composition are presented for 17 sites. A clustering technique was applied to the taxa/site matrix to demonstrate the degree of association between sites varying in zinc concentration. Chandler biotic scores were found to be lowest at sites affected by high zinc levels and/or dense growths of the alga Stigeoclonium tenue. The role of elevated zinc levels and algal growth in determining the diversity and abundance of benthos is discussed.
85 citations
TL;DR: This investigation was conducted to characterize the algal inhibitory material originally isolated by Proctor (1957b) from Chlamydomonas and found evidence that unsaturated fatty acids were responsible for the majority of the toxicity.
Abstract: This investigation was conducted to characterize the algal inhibitory material originally isolated by Proctor (1957b) from Chlamydomonas. Analysis of purified extracts demonstrated that the inhibitor was a mixture of fatty acids. The identity and relative percentages of most of the components of the mixture were determined by GLC analysis. There is evidence that unsaturated fatty acids were responsible for the majority of the toxicity.
79 citations
TL;DR: In this article, an 18-month study was undertaken to determine the seasonal contribution and detrital processing of autochthonous plant litter in the Great Bay Estuary System of New-Hampshire-Maine, USA and adjacent open coast.
Abstract: An 18-month study was undertaken to determine the seasonal contribution and detrital processing of autochthonous plant litter in the Great Bay Estuary System of New-Hampshire-Maine, USA and adjacent open coast. Four species were studied: the halophytes, Spartina alterniflora Loisel. and Zostera marina L. and the seaweeds, Ascophyllum nodosum (L.) Le Jolis and Fucus vesiculosus L. v. spiralis Farlow. Monthly strand line collections at estuarine and open coastal sites provided information on the seasonal influx of litter derived from each species. Detrital inputs from S. alterniflora and Z. marina were maximal in the spring and summer, respectively. Seaweed litter was abundant (35 to 85% of the total strand line) throughout the year. The seaweeds contributed 1 to 3 times as much detrital material as the vascular plants within the Estuary, and 50 times as much on the open coast. In situ measurements of decomposition, using nylon, mesh bags, were made for each species under several environmental conditions. Seaweeds decomposed 3 to 10 times faster than vascular plant litter under similar conditions. Decomposition rates and changes in the nutrient content of litter were dependent on surrounding environmental conditions. Continual nutrient depletion occurred in litter within the strand line. Nitrogen and phosphorus enrichment were observed under submerged conditions and were attributed to microbial activity and rapid leaching of carbonaceous substrates. A computer simulation model was developed to validate the field data and to predict seasonal detrital carbon input by each species. The significance of autochthonous input is discussed in relation to other detrital sources.
TL;DR: Experiments showed larval growth on the reef was inversely related to density, and the lake as a whole produced relatively larger flies in a year when larval and pupal densities were relatively low, which illustrates the power of habitat quality by itself in determining spatial patterns of abundance in a lake.
Abstract: The population of Ephydra cinerea was studied during three summers when dissolved solids levels were about 130 g/l. All life stages are present year-round, but there is apparently some coordination of the initial pulse of adult emergence in June. There are probably 1–2 generations per year. Eggs are deposited on the water surface; inputs to three locations were similar. Larvae successfully avoid the large benthic area covered by an anaerobic monimolimnion. They tend to immigrate from substrates where they grow relatively poorly, and to remain on substrates where they grow better. Consequently, larval densities are more than ten times higher on reef and shallow water mud substrates than on sand. This marked spatial specialization in the absence of substrate-specific predators or competitors illustrates the power of habitat quality by itself in determining spatial patterns of abundance in a lake. Experiments showed larval growth on the reef was inversely related to density, and the lake as a whole produced relatively larger flies in a year when larval and pupal densities were relatively low. Yearly production by E. cinerea is roughly 50 g/m2, about 88% of which comes from reefs and shallow water mud areas covering only 18% of the bottom area. Past studies indicate that blue-green algae dominate the lake's benthic flora when salt concentrations are high (due to low lake levels), and diatoms take over when salt concentrations are low. Fly abundance appears to be inversely related to salinity. The lake's present high planktonic primary production is equal to that of eutrophic freshwater lakes, yet it has water clarity more characteristic of an oligotrophic lake. The high water clarity (which makes possible the high benthic production) probably depends on the absence of phytoplankters that can both tolerate the high salinity and avoid being eaten by Artemia salina. Continued dilution of the lake will probably upset this situation and result in reorganization of the lake's energy flow pattern.
TL;DR: The in situ clearance rates of several rotifer species from a small, temperate eutrophic lake were measured using three radioactive tracer cell-types, a bacterium, a yeast, and alga, indicating niche diversification in food resources.
Abstract: The in situ clearance rates of several rotifer species from a small, temperate eutrophic lake were measured using three radioactive tracer cell-types, a bacterium (Aerobacter), a yeast (Rhodotorula), and alga (Chlamydomonas). Rates were below 10 μl/ anim/h but varied significantly among species. Keratella cochlearis, Kellicottia bostoniensis, and Conochilus dossuarius ingested all three tracer cells but rates varied substantially with tracer cell-type. Polyarthra dolichoptera and P. euryptera ingested only the algal cells. Co-occurring forms of K. cochlearis and species of Polyarthra differed markedly in size and in tracer cell utilization, indicating niche diversification in food resources.
TL;DR: The symbiosis between the freshwater sponge Ephydatia fluviatilis and a chlorella-like green alga is not obligate and only occurs when the sponge grows in the light.
Abstract: The symbiosis between the freshwater sponge Ephydatia fluviatilis and a chlorella-like green alga is not obligate and only occurs when the sponge grows in the light. The algae accumulate intracellular pools of sucrose and glucose and translocate between 9 and 17% of the total photosynthate to the host. The principal product translocated is glucose which is fed directly into the sponge metabolic pool. White sponges transplanted back into the river in the shade grew logarithmically with a mean doubling time of 12 days. Sponges transplanted into illuminated habitats did not grow. It is unknown how the sponge acquires its algal symbiont.
TL;DR: The selective nature of feeding by baltic herring in the Bothnian bay was studied by comparison of the food intake and the abundance of potential zooplankton prey to reveal that the largest food items available are selected.
Abstract: The selective nature of feeding by baltic herring (Clupea harengus, L.) in the Bothnian bay was studied by comparison of the food intake and the abundance of potential zooplankton prey. Simultaneous sampling of zooplankton and capture of fish revealed that:
TL;DR: It is demonstrated that the growth of stream insects is directly proportional to the number of degree-days experienced by a population.
Abstract: The growth of aquatic insects in a small mountain stream was studied with emphasis on water temperature. Growth of the five dominant species was examined in relation to degree-days. This measure accounts for time and the minimum temperature necessary for insect growth. All species showed reduced specific growth rates with lower temperatures, but some (Ephemerella dorothea, Leuctra tenella, Neumoura wui) did not stop growing at even the lowest water temperatures. Both Diplectrona modesta and Paraleptophlebia assimilis had minimum growth temperatures. Studies demonstrated that the growth of stream insects is directly proportional to the number of degree-days experienced by a population.
TL;DR: Criticism of Hadzi's, Steinbock's and Hanson's theories, stating that acoels turbellarians are derived from plasmodial ciliates and are the most primitive metazoa, leads to disagreements on lower metazoan phylogeny.
Abstract: 1963: disagreements on lower metazoan phylogeny ‘Are phylogenetic theories subjective views? Can any man propose his own phylogeny or can we get definite scientific solutions?’ asked Remane (1963) in criticism of Hadzi’s (1944, 1953), Steinbock’s (1952, 1958, 1963) and Hanson’s theories (1958, 1963), stating that acoels turbellarians are derived from plasmodial ciliates and are the most primitive metazoa.
TL;DR: The sessile rotifers are those species which as adults are permanently attached to surfaces, and complete understanding of the evolution of this group is not possible without considering the planktonic forms.
Abstract: The sessile rotifers are taxonomically defined as all the individuals belonging to the families Flosculariidae, Conochilidae (Order Flosculariaceae), and Collothecidae (Order Collothecaceae) (Edmondson, 1940, 1944). Freeswimming species are, however, found in each family. The Conochilidae are totally planktonic. Although most of my remarks in this review will concern those species which as adults are permanently attached to surfaces, complete understanding of the evolution of this group is not possible without considering the planktonic forms.
TL;DR: Freshwater zooplankton species differ in their consumption of live and dead algal cells when tested in situ, and both the copepod Diaptomus spatulocrenatus and a cladoceran, Bosmina sp.
Abstract: Freshwater Zooplankton species differ in their consumption of live and dead algal cells when tested in situ. Using isotopicallylabeled living and heat-killed Chlamydomonas reinhardti as models for phytoplankton and detrital ses ton, respectively, we tested differential feeding on these foods by 3 rotifers and 2 microcrustaceans. Keratella cochlearis selectively feeds on ‘detrital’ materials while 2 sympatric rotifer species, Conochilus dossuarius and Kellicottia bostoniensis show no ability to discriminate between the living and dead foods. Both the copepod Diaptomus spatulocrenatus and a cladoceran, Bosmina sp., differentially consume living cells.
TL;DR: It is suggested that microzooplankton, increasing in numbers as a result of the reduction in macrozooplanking competitors, sustain grazing activity for a considerable period after the pesticides have been applied and support the conclusions of others that release from predation is an important factor in the increase in algae following treatment with organophosphorus pesticides.
Abstract: Changes in time in chlorophyll a and pheopigments of ponds treated with the organophosphorus insecticides Abate® and Dursban® were compared with those in untreated but otherwise similar ponds. Treated ponds consistently exhibited a severalfold increase in chlorophyll a, 30 to 50 days following application. Pheopigment concentrations did not decline in treated ponds and were frequently higher than in control ponds. Increases in pheopigment concentration could be correlated with increased numbers of microzooplankton following treatment. It is suggested that microzooplankton, increasing in numbers as a result of the reduction in macrozooplankton competitors, sustain grazing activity for a considerable period after the pesticides have been applied. These data support and extend the conclusions of others that release from predation is an important factor in the increase in algae following treatment with organophosphorus pesticides.
TL;DR: The food of lake-dwelling Erpobdella octoculata, Glossiphonia complanata and HelobDella stagnalis was determined by exposing potential prey organisms to leech attack in dishes, in the laboratory, using four experimental regimes.
Abstract: The food of lake-dwelling Erpobdella octoculata, Glossiphonia complanata and Helobdella stagnalis was determined by exposing potential prey organisms to leech attack in dishes, in the laboratory. For each prey species, four experimental regimes were used; these contained prey and leeches of different sizes.
TL;DR: It is suggested that analysis of sedimentary associations of scales, bristles and cysts could be used to improve cyst taxonomy in Mallomonas.
Abstract: Scales and bristles ofMallomonas crassisquama (Asmund) Fott andM. elongata Reverdin are reported from the laminated sediments of Laukunlampi, a small kettlehole lake in N. Karelia, Finland. The white summer laminae in the deeper sediment are composed almost entirely ofM. crassisquama scales and bristles. The taxonomy, ecology and distribution ofM. crassisquama andM. elongata are briefly discussed and factors influencing the preservation of scales and bristles in sediments are considered. It is suggested that analysis of sedimentary associations of scales, bristles and cysts could be used to improve cyst taxonomy inMallomonas.
TL;DR: Twenty-four Central Amazonian Várzea and Ria lakes, lateral to the Rio Negro and the Rio Solimões, were studied for a year and are classified here in terms of physical, chemical and microbiological characteristics.
Abstract: Twenty-four Central Amazonian Varzea and Ria lakes, lateral to the Rio Negro and the Rio Solimoes, were studied for a year and are classified here in terms of physical, chemical and microbiological characteristics. White water (W), mixed water (M) and black water (B) lakes are ranked according to bacterial densities, electrical conductivity, pH, DO, POC, Fe, Si02 and PO4 consumption in the following order W > M > B. The range of Vmax decreased as net primary production increased. Further differentiation among the three lake types is made on the basis of dominant algal species and species diversity.
TL;DR: Atomic absorption spectrophotometric analysis showed that the algae and molluscs concentrated similar levels of most metals, however, of the twelve organisms, Brachydontes variabilis had the highest copper, Patella coerulea and Colpomenia sinuosaHad the highest iron, and Pinctada radiata had thehighest zinc values with rather elevated cadmium.
Abstract: Twelve species of intertidal algae and molluscs from Ras Beirut, Lebanon have been investigated for their heavy metal content. Atomic absorption spectrophotometric analysis showed that the algae and molluscs concentrated similar levels of most metals. However, of the twelve organisms, Brachydontes variabilis had the highest copper, Patella coerulea and Colpomenia sinuosa had the highest iron, and Pinctada radiata had the highest zinc values with rather elevated cadmium. Cystoseira spinosa concentrated the lowest levels of zinc, and nickel was variable in all organisms. Seasonal comparisons of metal levels were also considered in three algae and three molluscs studied previously. The only signs of seasonal variation in the algae were with nickel and iron in Halimeda tuna and lead in Pterocladia pinnata. Both cadmium and lead were generally lowest in the spring samples of the algae. Lead and nickel concentrations in the molluscs were generally highest in the summer and lowest in the spring. Slight seasonal trends were seen with lead and iron in Brachydontes variabilis and lead in Monodonta turbinata. The lack of comparison data from the Mediterranean, particularly the eastern basin, makes it essential that studies of this nature be continued.
TL;DR: The literature on variation in Keratella is reviewed and an attempt is made at explaining the existence of discontinuous variation within a single lake.
Abstract: The literature on variation in Keratella is reviewed. The old idea of a thorough endogenous control has to be rejected, but internal factors ought to play a certain role beside influences from current and previous environment. In certain cases there is probably a succession of genetically different clones during the course of the year (cf. King, 1972, 1977), but the seasonal variation in lake populations of, e.g., K. cochlearis ought to be mainly non-genetical. There is some evidence that temperature and food exert an influence on the morphology, via rate of growth, but probably other abiotic and biotic factors are at work as well. The existence of allometric relationships is clearly demonstrated for several species. The variation in spine length has been suspected by some authors to consititute just the function of size variation which is thus considered primary. Some of the variation found is obviously non-adaptive. An attempt is made at explaining the existence of discontinuous variation within a single lake. Implications on taxonomy and speciation are briefly discussed.
TL;DR: A principal component and discriminant function analysis of zooplankton from the Sanyati Bay, Lake Kariba, indicated that the distribution of plankton was associated with the riverine in-flow into the lake.
Abstract: A principal component and discriminant function analysis of zooplankton from the Sanyati Bay, Lake Kariba, indicated that the distribution of plankton was associated with the riverine in-flow into the lake.
TL;DR: Environmental cues associated with population density are responsible for the production of sexual females in monogonont rotifer Asplanchna girodi samples of Golf Course Pond during the spring of 1977.
Abstract: The monogonont rotifer Asplanchna girodi was continuously present in daily and bi-daily plankton samples of Golf Course Pond during the spring of 1977. Two cycles of sexual reproduction occurred during this period. By isolation and culture of females it was possible to determine the reproductive type of collected individuals. Data thus obtained suggest that environmental cues associated with population density are responsible for the production of sexual females.
TL;DR: Coloniality and secretion of a gelatinous matrix in Conochilus can be viewed as adaptations to limit mortality from invertebrate predation.
Abstract: Direct observations of behavioral interactions show that the predator A. girodi: 1) easily ingested Synchaeta pectinata, two forms of Keratella cochlearis cochlearis, and individuals of Conochilus unicornis and C. dossuarius enzymatically dissociated from their matrix; 2) rarely, if ever, captured Kellicottia bostoniensis and intact Conochilus; and 3) generally rejected the peritrich ciliate Rhabdostyla sp. and the dinoflagellate Peridinium sp. Coloniality and secretion of a gelatinous matrix in Conochilus can be viewed as adaptations to limit mortality from invertebrate predation. Intraspecific variability in the feeding responses of A. girodi is considered.
TL;DR: Brachionus plicatilis raised in the authors' laboratory in sea water reproduces asexually even under high crowding conditions (at least 40 individuals per ml) and produces mictic females, males and resting eggs by reducing the concentration of the sea water culture medium.
Abstract: Brachionus plicatilis raised in our laboratory in sea water reproduces asexually even under high crowding conditions (at least 40 individuals per ml). Amictic females were induced to produce mictic females, males and resting eggs by reducing the concentration of the sea water culture medium. Mictic females and males appeared predominantly among the progeny produced by the amictic females during 4 days following their transfer into 25% sea water. Resting eggs appeared first 5–12 days after the onset of the experiment. Following the disappearance of males, the culture consisted of amictic females.
TL;DR: An account is given of the size, form, texture, colour, cohesion and composition of the faeces of 41 species of invertebrates found in chalk streams and the importance ofFaeces production relative to the bulk of stream bed sediments is discussed.
Abstract: An account is given of the size, form, texture, colour, cohesion and composition of the faeces of 41 species of invertebrates found in chalk streams The relationships between the character of the faeces and the taxonomic positions and habits of the producers are considered The importance of faeces production relative to the bulk of stream bed sediments is discussed Faeces of different origins accumulate in different areas of the stream bed and these differences may be associated in part with their form and structure and in part with the distribution of the species from which they originate In the summer months tubificid worms alone may be responsible for reworking between 03% and 05% of the fine particulate material in sediments every day