Water quality of the Modder River,South Africa

The Modder River is a relatively small river in the central region of the Free State Province, South Africa and has a mean annual runoff of 184 × 106m³. Botshabelo is a city, which has developed in the catchment area of the river, and its sewage outflows are discharged into the Klein Modder, a tributary of the Modder River. This study was conducted in order to determine the influence of Botshabelo's sewage outflow on the water quality of the river. It was determined that the Modder and Klein Modder Rivers do not generally follow distinctive seasonal patterns in terms of chemical parameters, although NO₃-N and PO₄-P concentrations usually increase with increasing flow and conductivity decreases with increasing flow. Physical parameters such as turbidity, flow and temperature did however follow distinctive seasonal patterns from February 1996 to December 1997, as did phytoplankton growth. Low chlorophyll-a concentrations were exhibited in the winter and higher concentrations during spring. In the Klein Modder River, algal blooms occurred more frequently, and the algal biomass was higher than in the Modder River. This could be ascribed to the higher nutrient concentrations and lower flow velocities in the former. The inflow of the Klein Modder River into the Modder River caused on average, 112% increase in PO₄-P, 171% increase in NO₃-N, 50% increase in chlorophyll-a concentration, and 230% increase in E. coli counts.     

FURTHER OBSERVATIONS ON THE BREEDING BEHAVIOUR OF LABEO UMBRATUS (SMITH) (PISCES: CYPRINIDAE)

SUMMARY

Breeding behaviour of Labeo umbratus was observed in the Modder River, Orange Free State, and ova were collected from below the site and hatched. Fry were reared for 12 months to confirm the identification of the ova collected. The behaviour of spawning fish and the oviposition site are described.     

Can resource use be the link between productivity and species richness in mammals?

Species richness has been shown to be affected by primary productivity at various spatial scales. However, the mechanisms behind this effect are still poorly understood. Under the assumption that primary productivity is directly related to energy availability for an animal assemblage, the hypotheses are that (i) primary productivity will affect the number of ways different food resources can be combined into species specific niches and (ii) it will also determine the number of specialist species that can be supported. These hypotheses were tested on the herbivorous mammalian fauna of Australia. Productivity only had a weak effect on the number of food resource combinations in this case. Specialization was most common at low and high productivity. In addition there were significant differences in where different types of specialization was the most common. This study seeks an energetic mechanism to explain an energetic relationship and though no clear effect was found for resource use it identified a possible link between productivity and species richness.     

疏勒河流域气候变化和人类活动对植被NPP的相对影响评价

气候变化和人类活动是对陆地生态系统碳循环产生重要影响的两个因素,定量评估气候变化与人类活动对植被净初级生产力(NPP)的相对影响,对深入理解其驱动机制和控制荒漠化发展具有重要意义。以疏勒河流域为研究区,利用遥感和气象数据计算潜在NPP(PNPP)及其与实际NPP(ANPP)之间的差值,分别衡量了气候变化和人类活动对流域NPP的相对影响。研究结果表明:(1)2001—2015年疏勒河流域年ANPP整体呈缓慢增加趋势,与全国和西北地区相比,普遍较低,流域植被整体生产力水平不高。流域年ANPP空间分布呈现上游祁连山区和中下游绿洲区ANPP较高,而中下游荒漠戈壁区ANPP较低的分布格局。(2)2001—2015年流域年PNPP的变化趋势表明,降水量的变化是导致疏勒河流域植被退化加剧或缓解的主要气候驱动因素,但气温的变化对植被的影响较为复杂。(3)2001—2015年流域大部分地区植被退化系人类活动造成的,但人类活动的负向影响力在减弱。(4)气候变化和人类活动对植被NPP的相对影响均表现出明显的空间异质性,其中人类活动是疏勒河流域植被变化的主要驱动因素。     

Descriptive parameter evaluation in mammalian cell culture

Several methods exist for assessing population growth and protein productivity in mammalian cell culture. These methods were critically examined here, based on experiments with two hybridoma cell lines. It is shown that mammalian cell culture parameters must be evaluated on the same basis. In batch culture mode most data is obtained on a cumulative basis (protein product titre, substrate concentration, metabolic byproduct concentration). A simple numerical integration technique can be employed to convert cell concentration data to a cumulative basis (cell-hours). The hybridoma lines used in this study included a nutritionally non-fastidious line producing low levels of MAb and a nutritionally fastidious hybridoma with high productivity. In both cases the cell-hour approach was the most appropriate means of expressing the relationship between protein productivity and cell population dynamics. The cell-hour approach could be used as the basis for all metabolic population parameter evaluations. This method has the potential to be used successfully for both prediction and optimization purposes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Multi‐season occupancy models identify biotic and abiotic factors influencing a recovering Arctic Peregrine Falcon Falco peregrinus tundrius population

Critical information for evaluating the effectiveness of management strategies for species of concern include distinguishing seldom occupied (or low‐quality) habitat from habitat that is frequently occupied and thus contributes substantially to population trends. Using multi‐season models that account for imperfect detection and a long‐term (1981–2002) dataset on migratory Arctic Peregrine Falcons Falco peregrinus tundrius nesting along the Colville River, Alaska, we quantified the effects of previous year's productivity (i.e. site quality), amount of prey habitat, topography, climate, competition and year on occupancy dynamics across two spatial scales (nest‐sites, cliffs) during recovery of the population. Initial occupancy probability was positively correlated with area of surrounding prey habitat and height of nest‐sites above the Colville River. Colonization probability was positively correlated with nest height and negatively correlated with date of snowmelt. Local extinction probability was negatively correlated with productivity, area of prey habitat and nest height. Colonization and local extinction probabilities were also positively and negatively correlated, respectively, with year. Our results suggest that nest‐sites (or cliffs) along the Colville River do not need equal protection measures. Nest‐sites and cliffs with historically higher productivity were occupied most frequently and had lower probability of local extinction. These sites were on cliffs high above the river drainage, surrounded by adequate prey habitat and with southerly aspects associated with early snowmelt and warmer microclimates in spring. Protecting these sites is likely to encourage continued occupancy by Arctic Peregrine Falcons along the Colville River and other similar areas. Our findings also illustrate the importance of evaluating fitness parameters along with climate and habitat features when analysing occupancy dynamics, particularly with a long‐term dataset spanning a range of annual climate variation.     

The partitioning of macroinvertebrate diversity across multiple spatial scales in the upper Modder River System,South Africa

A method for assessing the alpha and beta diversity components of a macroinvertebrate community across numerous spatial scales is presented. Findings were not empirically linked to ecological questions as the purpose of this study was primarily the demonstration of a diversity partitioning method. Sampling was carried out at three sites on the upper Modder River in the Free State Province, South Africa between April 2008 and January 2009. Communities were analysed by investigating the relative frequency of species in specific biotopes, a Similarity Profile (SIMPROF) and cluster analyses of the Bray‐Curtis similarities between samples, and the partitioning of species richness and Shannon diversity across multiple spatial scales. Findings revealed that sites showed significant clustering (SIMPROF P < 0.05; <20% Bray‐Curtis similarity), and the species frequencies indicated preference to selected microhabitats. Species richness and Shannon diversity of macroinvertebrates differed significantly (5% confidence levels) from randomly simulated values for sampling sites, biotopes and seasons indicating that diversity is clustered and not homogeneously distributed. The diversity partitioning could have potential in diversity assessment for conservation biology, land management and environmental impact assessments.     

Self-sustaining populations, population sinks or aggregates of strays: chum (Oncorhynchus keta) and Chinook salmon (Oncorhynchus tshawytscha) in the Wood River system, Alaska

Small populations can provide insights into ecological and evolutionary aspects of species distributions over space and time. In the Wood River system in Alaska, USA, small aggregates of Chinook (Oncorhynchus tshawytscha) and chum salmon (O. keta) spawn in an area dominated by sockeye salmon (O. nerka). Our objective was to determine whether these Chinook and chum salmon are reproductively isolated, self-sustaining populations, population sinks that produce returning adults but receive immigration, or strays from other systems that do not produce returning adults. DNA samples collected from adult chum salmon from 16 streams and Chinook salmon from four streams in the Wood River system over 3 years were compared to samples from large populations in the nearby Nushagak River system, a likely source of strays. For both species, microsatellite markers indicated no significant genetic differentiation between the two systems. Simulations of microsatellite data in a large source and a smaller sink population suggested that considerable immigration would be required to counteract the diverging effects of genetic drift and produce genetic distances as small as those observed, considering the small census sizes of the two species in the Wood River system. Thus, the Wood River system likely receives substantial immigration from neighbouring watersheds, such as the Nushagak River system, which supports highly productive runs. Although no data on population productivity in the Wood River system exist, our results suggest source-sink dynamics for the two species, a finding relevant to other systems where salmonid population sizes are limited by habitat factors.     

A problem for biodiversity-productivity studies: how to compare the productivity of multispecific plant mixtures to that of monocultures?

The study of the relationship between species richness of a plant community and its productivity has received much attention, recently renewed by the concern on the loss of biological diversity at a global scale. Here, we briefly review some indices widely used in agronomic and competition experiments to compare monocultures and mixtures, and compare them to other, more recently designed ones. These various indices are then calculated for two experiments. In the first experiment, two grass and two legume species were grown at six levels of nitrogen availability, either in monocultures or in mixtures of the four species in a substitutive design; in the second experiment, five grass species were grown at 16 levels of total nutrient availability, either in monocultures or in mixtures of the five species in an additive design. These data clearly show that the conclusions drawn from the experiments depend on the index used to compare the experimental communities. We argue that a clear test of whether the productivity of communities increases with species richness requires that: (1) all species present in the multispecies assemblages also be grown in monocultures under the same environmental conditions, and (2) the productivity of these assemblages be compared to the most productive monoculture. We conclude that there are as yet very few cases where superior productivity of multispecies assemblages as compared to monocultures has been clearly shown.     

Contrasting life-cycle impacts of stream flow on two Chinook salmon populations

Stream flow affects many aspects of freshwater fish biology, but the extent to which variation in stream flow influences productivity of anadromous salmonid populations across their entire life cycle is not well known. We compared relationships of stream flow and productivity for Chinook salmon (Oncorhynchus tshawytscha) from two systems in the Salmon River basin in Idaho: the Lemhi River, a watershed subjected to intensive water use for irrigation, and Marsh Creek, a drainage with a natural hydrograph. We estimated rates of productivity based on monitoring at four life stages: the number of eggs initiating each cohort, juveniles migrating from the natal tributary past an outmigrant trap, smolts surviving to the Snake River, and adults returning to spawn. Using model selection techniques, we examined whether river flow experienced during these life stages explained variation above and beyond predictors of climate associated with each stage. In the Lemhi River, tributary stream flow during early residence exhibited strong correlations with egg–trap, egg–smolt, and egg–adult return rates, and was consistently a better predictor of productivity than stream flow occurring during late summer. Model selection indicated that early rearing flow was the single best predictor of both egg–trap and trap–smolt transition rates in the Lemhi River, and path analysis revealed a strong set of pathways linking rearing flow to adult return rate primarily through egg–trap productivity. These patterns were much less strongly exhibited or nonexistent in Marsh Creek. However, for both populations, migration flow in the Columbia River was the best predictor of smolt–adult return rates. Potentially confounding climatic variables exhibited relatively weak effects upon both early life histories and tributary flow, but were included in the best models of migration flows and smolt–adult return rate. These results suggest that effects of stream flow on juvenile salmonids in flow-altered systems can have substantial impacts on returning adults.     

香溪河河流连续统特征研究

以香溪河附石藻类密度、藻类叶绿素a浓度、Shannon-Wiener多样性指数及生态系统初级生产力随河流级别的变化为例探索该河流的连续统特征。结果表明,附石藻类密度、藻类叶绿素a浓度和Shannon-Wiener多样性指数总体上都有随着河流级别增加而增加的趋势,但在1～3级河段之间这种趋势并不明显,甚至出现了逆转。河流初级生产力也有随河流级别增加而增加的趋势,并在第4级河流达到最大,随后有所下降。在全水系范围内河流初级生产力(P)与群落呼吸(R)比值P／R均大于1,说明香溪河是一条以自养生产为主的河流。所研究的特征并不完全与连续统概念的预测相一致,表明河流已经受到了一定程度的人为干扰。     

Primary productivity of the River Ely,South Wales,U.K.

The present study was carried out on the non-tidal reaches of the River Ely, South Wales, from October 1979 to October 1980. The seasonal variations of the chlorophyll-a content of the phytoplankton was unimodal with one maximum in May and a minimum in December. The chlorophyll-a content varied from 0.277 to 41.259 mg m^?3. The primary productivity showed a bimodal seasonal distribution with two maxima in May and September and lower values throughout the remainder of the year, particularly in winter. The value for the primary productivity varied from 0.269 to 24.302 mg C m^?3 h^?1. A positive correlation was obtained between chlorophyll-a content and primary productivity. The seasonal distribution of the dominant algal species and the saprobity of the River Ely were also studied. The diatom species almost showed a similar seasonal periodicity. Their concentrations were low during the winter months and high during most of the spring and summer months. Many of the dominant diatom species found in the phytoplankton populations were either considered by the other authors as saprobic (Nitzchia palea) or as inhabitants of eutrophic waters (Gomphonema parvulum, Navicula cryptocephala and Synedra ulna). Chlamydomonas spp. were the most abundant green algae followed by Chlorella vulgaris. The effect of sewage effluent disposal and cattle excreta at three of the sampling sites might partly explain the presence of high Chlamydomonas spp. populations at those sites. Physical factors (low flow rates, high transparency and water temperature) and organic pollution at some sampling sites seemed to play an important role in increasing the number of algal species during spring and summer. The non-tidal reaches of the River Ely were found to be β-mesosaprobic above and below Station 5 and α-mesosaprobic at the latter station and therefore, the river can be considered as polluted at Station 5 and mildly polluted at the others.     

A step-wise discriminant analysis of the effects of long term coal mine drainage and coal dredging on phytoplankton of the Guyandotte River

Phytoplankton was sampled from the lower 60 miles portion of the Guyandotte River where three active coal dredging operations presently exist and five more permits are pending. Comparisons were made with phytoplankton from a similar stretch of the Mud River, a stream of minimal mine drainage and no coal dredges along its entire course.Diatoms were the predominant planktonic algae on both streams. The number of all phytoplankton species was 24% higher for the Mud River than for the Guyandotte River. Equitability and species diversity indices plus the distribution of mine water indicator algae show that the Guyandotte River is heavily polluted with domestic wastes and mine drainage. No correlation could be established for turbidity, specific conductance, or pH and locations of dredging operations, when the data were analyzed for differences among sampling stations.Step-wise discriminant analysis was used to compare the two streams and the biological, physical, and chemical variables. Based on coefficients for canonical variables, conductivity and pH are the two most influential variables in separating the two streams. Analysis of variance indicates that the canonical means of the stations on the Guyandotte River are significantly different from the Mud River stations.     

Diversity of life strategies and population structure of Kamchatka mykiss <Emphasis Type="Italic">Parasalmo mykiss</Emphasis> in the ecosystems of small salmon rivers of various types

The diversity of life strategies and population structure of Kamchatka mykiss Parasalmo mykiss in the ecosystems of small salmon rivers of various types are considered. Hydrogeomorphological differences of the model rivers Kol and Kekhta are found. The preferred habitats are investigated, and their area is determined. It is shown that, in the Kol River, the mykiss having a resident life strategy predominated, and in the Kekhta River—the mykiss with migratory strategy. The key parameter controlling the prevalence of life strategies in each river is the ratio of the area of spawning grounds to the area of feeding grounds and their productivity. The hypothesis is confirmed that, in complex river systems, due to the diversity of biotopes and a higher productivity, the food resources are sufficient for maturation of mykiss and for realization of the resident life strategy (without migration to the sea for feeding). In small rivers of the channel type with their insufficient food resources, the specimens having a migratory life strategy prevail.     

Ideal nutrient productivities and nutrient proportions in plant growth

Abstract I propose that one single formulation can be applied to relate growth and content of several nutrients, including the most important macronutrients, of most plant species. The plant growth rate is proportional to the nutrient content minus a given minimal concentration of the nutrient in minimum. The proportionality factor, the nutrient productivity, and the minimum concentration are species specific properties. The nutrient productivity formulation is shown to apply for very different plant species and for different nutrients.     

Regional differences in responses of chinook salmon populations to large-scale climatic patterns

Aim To quantitatively explore the extent to which many different populations of the same species (chinook salmon, Oncorhynchus tshawytscha) respond cohesively to a common large‐scale climatic trend. Location The Columbia River basin of the northwestern US. Methods I used regression analyses to describe the downward trend in population growth (number of recruits per spawning adult) for thirteen populations of chinook salmon distributed among three geographical regions: Snake River, Upper Columbia River and Middle Columbia River. I then used residuals from these regressions to characterize per capita productivity for each brood year. Positive residuals indicated productivity higher than that predicted by the time series, while negative residuals revealed years in which productivity was lower than predicted. I next used analysis of covariance (ancova ) to test the null hypothesis that associations between ocean/climate conditions and deviations from predicted population growth did not vary among geographical regions. All ancova s used residuals generated from the regressions as the response variable, geographical region as the main effect, and climatic condition [characterized by the Pacific Decadal Oscillation index (PDO)] as the covariate. A major climate shift occurred in 1977, and because the association of the PDO with salmon productivity varied between the pre‐ and post‐1977 climate regimes, I analysed data from the two regimes separately. Results There were marked impacts of climate on salmon production that varied among geographical regions and between decade‐scale climate regimes. During the pre‐1977 climate regime, productivity of salmon populations from the Snake River tended to exceed expectations (i.e. residuals were positive) when values of the PDO were negative. In contrast, this pattern was not evident in populations from the upper or middle Columbia Rivers. During the post‐1977 regime when ocean productivity was generally lower, the association of the PDO with salmon productivity changed – productivity tended to fall short of expectations (i.e. residuals were negative) when values of the PDO were negative. Main conclusions Understanding the linkages between salmon populations and climate is critical as managers attempt to preserve threatened salmon populations in the face of both natural or human‐induced climate variation and the litany of human activities affecting salmon. An important step in this understanding is the recognition that the response to ocean/climate change by salmon populations of the same species and river basin is not necessarily homogeneous.     

Dinoflagellate cysts as indicators of water quality and productivity in British Columbia estuarine environments

Palynological analyses of 60 surface sediment samples from estuarine environments near Vancouver Island, including the Georgia Strait (GS), the Effingham (EFF) and the Seymour–Belize (SB) Inlets were performed in order to document the distribution of dinoflagellate cyst assemblages and their relationship to hydrographic conditions, productivity and nutrient concentrations. We tested transfer functions using the analogue method, and suggest that dinoflagellate cyst assemblages can be used to reconstruct primary productivity, temperature and salinity. The EFF and SB Inlets are characterized by a dominance of autotrophic taxa, particularly Operculodinium centrocarpum, whereas the Protoperidinioid and gymnodinial heterotrophic taxa such as Quinquecuspis concreta and Brigantedinium spp. dominate the assemblages of the GS. Multivariate analysis shows that this distribution is closely linked to primary productivity, sea-surface temperature (SST) and spring silica concentration. The abundance of autotrophic taxa in the EFF and SB Inlets is associated with high primary productivity and low summer SST, indicating summer upwelling of coastal British Columbia, whereas the heterotrophic taxa that characterizes the GS assemblages are related to low productivity, high summer SST and high silica concentration during spring. Multivariate analysis shows that the most important environmental parameters related to dinocyst distribution in the restricted embayment of the GS, are distance to the shore, distance to Vancouver Harbor, spring sea surface salinity (SSS), spring phosphate concentration and spring productivity. The autotrophic taxa are generally more common in coastal and shallow waters, but Spiniferites ramosus and Pentapharsodinium dalei show an opposite correlation to spring productivity and salinity. P. dalei is particularly abundant around Vancouver Harbor, near highly urbanized shores and within the Fraser River plume, where salinity is low and spring productivity and continental runoff are high. S. ramosus shows its highest abundance on the western coast of GS. Protoperidinioid and gymnodinial cysts characterize distal zones within the central and southern GS that are associated with a mixture of brackish waters coming from the Fraser River and deep upwelling waters entering the GS via Juan de Fuca Strait. The relationship between dinoflagellate cyst assemblages and primary productivity in these estuarine systems differs from that in oceanic and outer neritic zones, where the abundance of heterotrophic taxa is commonly associated with upwelling and high productivity.     

GROWTH, PRIMARY PRODUCTIVITY, AND NITROGEN FIXATION POTENTIAL OF NODULARIA SPP. (CYANOPHYCEAE) IN WATER FROM A SUBTROPICAL ESTUARY IN THE UNITED STATES

Nodularia is a halotolerant, filamentous, dinitrogen-fixing cyanobacterium that forms massive blooms in some coastal oceans, estuaries, and saline lakes worldwide. Although the genus is globally distributed, its blooms are sporadic and appear to be confined to certain water bodies. Blooms are frequently associated with phosphorus enrichment; therefore Nodularia may benefit from increased anthropogenic nutrient loading to coastal waters. We studied the potential for Nodularia to grow in the nitrogen-limited Neuse River Estuary (North Carolina, U.S.A.) with laboratory growth experiments in Neuse River Estuary water and by examining physico-chemical data from the estuary. Analysis of nutrients (nitrogen and phosphorus), salinity, and temperature data from the Neuse River Estuary between 1994 and 1998 revealed that suitable conditions for Nodularia prevailed during the summer of each of these years for time spans ranging from 1.5 to 5 months. Growth of two laboratory strains in Neuse River Estuary water was as fast or slightly slower than in artificial growth medium, as long as the culture inoculum had phosphorus reserves. Phosphorus addition did not stimulate growth of already phosphorus-sufficient inocula. Phosphorus starvation of the inoculum before the experiment decreased growth rates in the estuarine water unless additional phosphorus was supplied. Although phosphorus addition had a stimulatory effect on dinitrogen fixation and productivity, the effect differed for the two Nodularia strains. Results suggest that growth of Nodularia in North Carolinian estuaries is possible, and that such growth would be phosphorus-limited at times. Phosphorus availability may determine the times and locations for potential establishment of Nodularia in this and similar estuarine ecosystems.     

Ergonomics in traditional Iranian industries.

It is an acknowledged fact that Iranian carpet weavers are subject to excessive fatigue. Earlier investigation has shown this to be largely due to a non-ergonomic body position while working at a traditional loom. It would appear that significantly increased production could be achieved by eliminating or reducing this fatigue. An Iranian engineer has attempted to do this by inventing a metal loom which takes ergonomic factors into consideration. The purpose of this study was to evaluate the effect of the new loom by comparing the productivity of two groups in Kerman, Iran: one using the new ergonomic loom and the other using the traditional loom. In preliminary investigations various factors were taken into account so that the two groups might be considered comparable. After several observations the average productivity of each weaver was calculated (according to knots per day). The results showed that the ergonomic loom had the highest productivity figures for both sexes and that increased productivity was directly related to the degree of comfort of the carpet weavers.     

Population structure and the anthropogenetic traits of Shortzy in the Mras-Su River basin

Demographic and phenotypic study of a population of Shortzy living along the Mras-Su River and in the Abakan River valley was carried out. The results of population genetic analysis of certain monogenic characters (AB0, PTC) as well as some dermatoglyphic traits and qualitative anthropometric traits are presented. The population was shown to be isolated. The level of gene flow in the population from the outside regions is equal to about 3-6%. The structure of the mountain Shortzy population was shown to approach the "stepping-stone" type. Considerable heterogeneity in the distribution of the traits in question was revealed. The similarity measures in the distribution of the values of three groups of traits were shown to be related to the extent of gene flow between subpopulations. Based on this analysis, two assumptions on the possible origins of the Shortzy population which had migrated from the mountains to the Abakan River valley about 250 years ago are formulated. Most probably, the modern phenotype of this group of Shortzy reflects the influence of other ethnic groups.