Assessing nutrient salts and trace metals distributions in the coastal water of Jeddah,Red Sea

In this study, eighteen sites at Jeddah coastal area, Red Sea, have been assessed for water quality status, depending on nutrients, metals, Chlorophyll-a (Chl-a) and physical variables during 2018 and 2019. The investigated parameters of the Water Quality Index (WQI) are temperature, pH, salinity, dissolved oxygen (DO), DO saturation, oxidizable organic matter (OOM), suspended particulate matter (SPM), Chl-a, ammonium, nitrite, nitrate, total nitrogen, reactive phosphate, total phosphorus, silicate, Zn, Fe, Mn Cu, Cd, Pb, and Ni. The results revealed that the pH values were slightly alkaline with a range of 7.85–8.20. The results of other parameters were as follow: salinity (36.95–42.61PSU), DO (5.22–6.67 mg/L), OOM (0.40–1.23 mg/L), SPM (12.39–21.5 mg/L), Chl-a (0.10–0.83 µg/L). The range of nutrients (μM) were 0.07–0.22, 0.45–1.47, 9.62–18.64, 23.31–57.65, 0.05–0.15, 0.55–2.78 and 2.54–5.51 for NH₄/N, NO₂/N, NO₃/N, TN, PO₄/P, TP and SiO₄/Si, respectively. Cluster analysis was used to classify the stations studied. From the current study, five clusters were found, indicating the need to perform cluster analysis in the water quality assessment process to confirm the durability and consistency of the data discovered in the current application.     

Mid-Po River zooplankton

The temporal crustacean-zooplankton variation in the mid-Po River (Italy) was analyzed from November 1974 through November 1982. Samples were collected at three stations at monthly intervals.Separate taxon-by-taxon multiple regression analyses (MLTRG) were carried out with zooplankton taxa as the criterion variable and river depth, river discharge and water temperature as the predictor variables. Moina brachiata and Eucyclops serrulatus were correlated with water temperature, Cyclops vicinus inversely correlated with temperature, Eudiaptomus padanus, C. vicinus and Daphniidae with river discharge; Copepodites inversely correlated with river depth.MLTRG showed that water temperature and river discharge account for about 15% of total zooplankton variation.Factorial analysis of variance (ANOVA) was carried out on residuals calculated from MLTRG. Among-years and among-months variation were significant for all the examined taxa. Significant years × months interactions indicated that seasonal variations were also different in different years.ANOVA stressed that there were still unexplained significant residuals in years and months variations.Weekly and daily samples collected in Summer 1979 were submitted to MLTRG and ANOVA as above. Among-week variations were significant for all the examined taxa, whereas among-days were significant for Daphiidae and M. brachiata (Cladocera), and not significant for any of the other taxa. Caution is recommended in interpreting the results of river zooplankton studies. Differences between species responses warn us not to pool species into larger taxa. Temporal variation changes from year to year, so long-time series are necessary to clarify the most important trends of river zooplankton.     

Use of stream order and biological indices to assess water quality in the Osage and Black river basins of Missouri

Significant variations in four biological measures of water quality with stream order and river basin were demonstrated for streams of the Black and Osage river basins of Missouri. Water quality criteria specific for each order and basin were then developed.Benthic macroinvertebrates from springs and stream orders 3–8 in the two river basins were sampled quarterly for one year with riffle nets and artificial substrate samplers. A total of 548 samples were taken at 137 stations. The average annual macroinvertebrate density, index of diversity, number of taxa, and number of mayfly and stonefly taxa were determined for each station. These measures showed significant differences (p < 0.05) across stream order within and between the two river basins. Total taxa, total mayfly and stonefly taxa, and diversity were highest in orders 4 and 5 with decreased values in lower and higher stream orders. Maximum organism densities occurred in intermediate order streams. These differences were attributed to the succession of physical changes from headwaters to mouth within each river and to the unique geomorphology of each catchment basin.Water quality criteria based on three of the four measures described above (with 95% confidence limits) were established for each stream order in each river basin. Criteria for the Osage River basin were then used to identify three streams in the basin affected by environmental disturbances (stream impoundment, channelization and sewage discharge). The use of order- and basin-specific criteria assures that the biological differences between streams caused by environmental disturbance can be distinguished from the natural biological differences between streams of different orders and drainages.     

Local variations in size and activity among Calanus finmarchicus and Metridia longa (Copepoda, Calanoida) overwintering on the west coast of Norway

Vertical net hauls were taken at thirteen stations between latitude6008'N – 6120'N and longitude 0304'E – 0700'Ein late November 1980. Size and activity characteristics ofCalanus finmarchicus and Metridia longa were studied. Significantdifferences were noted between C. finmarchicus from differentstations. Average body length, dry weight, protein and lipidcontents, gonad development, and ainylase and trypsin activitiesvaried but average gut fullness and trypsin/amylase ratio appearedconstant. M. longa from different stations showed significantdifferences in average body length, dry weight, protein content,amylase and trypsin activities and gut fullness, but there wereno apparent variations in lipid content and trypsin/ainylaseratio. Those animals inhabiting the most seaward station tendedto show the most specific local charactenstics. M. longa hadconsistently lower lipid proportion with higher gut fullnessand digestive-enzyme activities than C. finmarchicus. The resultstherefore indicate that C. finmarchicus had assumed a winterstate of low activity with dependence on stored energy, whileM. longo relied more upon utilization of available food.     

Free Cellular Riboflavin is Involved in Phase Shifting by Light of the Circadian Clock in Neurospora crassa

Phase shifting by light of the circadian conidiation rhythmof the Neurospora crassa strain band, of the riboflavin-deficientdouble mutant band rib2 and of the temperature-sensitive doublemutant band ribl was measured. Fluence response curves of theband strain exhibited two distinct steps, whereas those of bandribl and band rib2 revealed only one step. Maximum phase advancesobserved were 5.5 h in band and 10.4 h in the band rib strains.Sensitivity of band rib2 to light was proportional to the riboflavinconcentration in the growth medium over a 100 fold range. Extracellularflavin in the medium did not sensitize the strains. Riboflavinapplied after exposure to light showed no effect. Light sensitivitycorrelated with the level of cellular riboflavin. Four analogsof riboflavin, none of which can be phosphorylated, increasedthe sensitivity of Neurospora to light. Even at high riboflavinconcentrations in the medium, the sensitivity of the band rib2strain to light was not saturated. In addition, four riboflavinderivatives with bulky substituents at positions 3, 8 or 10of the isoalloxazine nucleus sensitized both strains. From ourdata, we conclude, that a) a cellular flavin controls the sensitivityof Neurospora crassa to light; b) that this flavin compoundis riboflavin; and c) that the active riboflavin is not proteinbound. ⁴Present address: Teikoku Women's University, Department ofHome Economics, 6-173 Touda-cho, Moriguchi-shi, Osaka, 570 Japan. (Received November 27, 1987; Accepted March 15, 1989)     

Modulation of Sucrose Content by Fructose 2,6-bisphosphate during Photosynthesis in Rice Leaves Growing at Different Light Intensities

Reddy, A. R. and Das, V. S. R. 1987. Modulation of sucrose contentby fructose 2,6-bisphosphate during photosynthesis in rice leavesgrowing at different light intensities.—J. exp. Bot. 38:828–833. The relationship between the rate of CO₂ fixation and sucroseconcentration in the leaves of rice (Oryza sativa L.) grownat different light intensities was investigated. Maximum sucrosecontent coincided with maximum rates of CO₂ fixation, achievedat a photon flux density of 1600 µmol m^–2 s^–1.The levels of sucrose and fructose 2,6-bisphosphate were alsocompared in the leaves under different light intensities. Fructose2,6-Msphosphate accumulated during growth at low light. Theactivity of fructose-6-phosphate 2-kinase was high in the leavesgrown at low light while that of fructose-2,6-bisphosphatasewas low. The activities of phosphoglucose isomerase and phospho-glucomutasewere slightly increased by growth at low light The activitiesof UDP glucose pyrophosphorylase were adversely affected invitro with increased concentrations of fructose 2,6-bisphosphatewhile those of sucrose phosphate synthase were moderately affected.Phosphoglucose isomerase and phosphoglucomutase were activatedby fructose 2,6-bisphosphate (8-0 mmol m^–3) by 12-15%.The results suggested that low light intensities during growthresult in an accumulation of fructose 2,6-bisphosphate whichmodulates the key enzymes of sucrose biosynthesis thus regulatingcarbon flow under conditions of limited photosynthesis. Key words: Oryza sativa, photosynthesis, sucrose synthesis, fructose 2,6-bisphosphate, light     

Abiotic drivers of interannual phytoplankton variability and a 1999–2000 regime shift in the North Sea examined by multivariate statistics

The Dutch coastal zone is a region of the North Sea with a marked interannual and long‐term abiotic and phytoplankton variability. To investigate the relationship between abiotic variability and phytoplankton composition, two routine water monitoring data sets (1991–2005) were examined. Multivariate statistics revealed two significant partitions in the data. The first consisted of interannual abiotic fluctuations that were correlated to Rhine discharge that affected the abundance of summer and autumn diatom species. The second partition was caused by a shift in the abiotic data from 1998 to 1999 that was followed by a shift in phytoplankton composition from 1999 to 2000. Important factors in the abiotic shift were decreases in suspended matter (SPM) and phosphate (DIP) concentrations, as well as in pH. The decrease in SPM was caused by a reduction in wind speed. The increase in water column daily irradiance from the decrease in SPM led to increases in the abundance of winter–spring species, notably the prymnesiophyte Phaeocystis globosa. Because wind speed is related to the North Atlantic Oscillation (NAO) index it was possible to correlate NAO index and P. globosa abundance. Only five abiotic variables representing interannual and long‐term variability, including Rhine discharge and NAO index, were needed to model the observed partitions in phytoplankton composition. It was concluded that interannual variability in the coastal phytoplankton composition was related to year‐to‐year changes in river discharge while the long‐term shift was caused by an alternating large‐scale meteorological phenomenon.     

Ecological studies on the phytoplankton of Boknafjorden, western Norway. II. Environmental control of photosynthesis

Both predicted (incubator) and measured (in situ) ¹⁴C-assimilationrates were studied from February to November 1981 at three stationsin Boknafjorden, a deep silled fjord of western Norway. Sampleswere taken from different light depths within the euphotic zone.A high degree of conformity was found between the two approaches.Daily values of carbon assimilation integrated over the euphoticzone varied between 0.05 and 1.4 g C m^–2. Yearly primaryproduction varied between stations from 82 to 112 g C m^–2(120–148 g C m^–2 when based on average light conditions).The light-saturation curve parameters ^B and P^B_max ranged from0.0056 to 0.0537 mg C mg Chla^–1 h^–1 µE^–1m² and from 0.7 to 8.5 mg C mg Chla^–1 h^–2 (in situassimilation numbers ranged from 0.9 to 9.3 mg C mg Chla^–1h^–1) respectively, which compare well with those publishedfrom the northwestern side of the Atlantic. The overall importanceof light in controlling photosynthesis throughout the year wasrevealed by the light utilization index , estimated to be 0.43mg C mg Chla^–1 E^–1 m². The maximum quantum yieldwas encountered on August 17, with 0.089 mol CE^–1. Chla/Cratios above and below 0.010 were found to be typical for shade-and light-adapted cells respectively. Assimilation numbers andgrowth rates were linearly related only when considering light-adaptedcells. Consistent with the findings of this study, the applicabilityof I_K, ^B and P^B_max as indicators of light-shade adaptation propertiesshould be questioned. Maximum growth rates were encounteredduring an autumn bloom of the dinoflagellate Gyrodinium aureolum(1.0 doublings day^–1), while 0.7–0.8 doublings day^–1were found for a winter bloom (water temperature of 2°C)of the diatom Skeletonema costatum. No unambiguous temperatureeffect on assimilation number and growth of phytoplankton couldbe recognized in Boknafjorden. A tendency towards increasedassimilation numbers coinciding with increased water columnstability was revealed. The highest P^B_max values were oftenencountered at almost undetectable nutrient concentrations.At least during summer this could be attributed to recyclingof nutrients by macro- and/or microzooplankton, responsiblefor a greater part of the primary production now being grazeddown. This study supports the convention that the depth of theeuphotic zone may extend considerably below the 1% light depth.     

The relationship between salinity, suspended particulate matter and water clarity in aquatic systems

This work presents and recommends 1) an empirically based new model quantifying the relationship between salinity, suspended particulate matter (SPM) and water clarity (as given by the Secchi depth) and (2) an empirical model for oxygen saturation in the deep-water zone for coastal areas (O₂Sat in %). This paper also discusses the many and important roles that SPM plays in aquatic ecosystems and presents comparisons between SPM concentrations in lakes, rivers and coastal areas. Such comparative studies are very informative but not so common. The empirical O₂Sat model explains (statistically) 80% of the variability in mean O₂Sat values among 23 Baltic coastal areas. The model is based on data on sedimentation of SPM, the percentage of ET areas (areas where erosion and transportation of fine sediments occur), the theoretical deep-water retention time and the mean coastal depth. These two new models have been incorporated into an existing dynamic model for SPM in coastal areas that quantifies all important fluxes of SPM into, within and from coastal areas, such as river inflow, primary production, resuspension, sedimentation, mixing, mineralisation and the SPM exchange between the given coastal area and the sea (or adjacent coastal areas). The modified dynamic SPM model with these two new sub-models has been validated (blind tested) with very good results; the model predictions for Secchi depth, O₂Sat and sedimentation are within the uncertainty bands of the empirical data.     

The Photocontrol of Spore Germination in the Fern Ceratopteris richardii

This paper describes how different wavelengths of light regulatespore germination in the fern Ceratopteris richardii. This speciesdoes not exhibit any dark germination. Maximum photosensitivityof the spores is reached 7 to 10 d after imbibition. An increasein the red light fluence above the threshold fluence of 10¹⁶quanta.m^–2 leads to a corresponding increase in germination.In sequential irradiation experiments, farred light can reversethis red light-mediated germination to the level observed withthe far-red light control. Blue light fluences above 10²⁰ quanta.m^–2can also block the germination response to red light. Moreover,this antagonistic effect of blue light is not reversed by subsequentirradiation with red light. It is therefore concluded that phytochromeand a distinct blue light photoreceptor control C. richardiispore germination. These interpretations are entirely consistentwith the published literature on other fern genera. (Received November 28, 1986; Accepted April 6, 1987)     

Action Spectrum of Light-Induced Membrane Hyperpolarization in Egeria densa

Action spectra of light-induced membrane hyperpolarization andphotosynthetic oxygen evolution were determined in cells ofEgeria densa. Since both spectra were similar, photosyntheticpigments are assumed to be involved in the light-induced membranehyperpolarization. However, the saturation levels of light fluenciesdiffered greatly between the two light reactions. Light-inducedhyperpolarization reached the maximum level at a light fluenceless than one-tenth that needed for saturation of photosynthesis. (Received June 5, 1985; Accepted November 13, 1985)     

Acclimation to low light intensity in photosynthesis and growth of Pseudo-nitzschia multiseris Hasle, a neurotoxigenic diatom

Pseudo-nitzschia multiseries, a neurotoxigenic diatom, was grownin batch culture at light intensities between 53 and 1100 µmolm^–2 s^–1. Cellular contents of carbon. nitrogen andchlorophyll a, and the relationship between photosynthesis andlight levels, were studied during exponential (day 4) and stationaryphases (day 12). In the stationary phase at low light, therewas an increase in cellular chlorophyll a and the initial slopeof P-I curves (^B), which permitted a photosynthetic assimilationof energy equivalent to that of cells grown at high light. Inpast incidents of domoic acid poisoning, this may have facilitateddomoic acid production at low light intensities.     

A dynamic model for suspended particulate matter (SPM) in rivers

Aim To present a general, process‐based river model for suspended particulate matter (SPM). Location General approach based on processes; data from Europe and Israel. Methods The model has been tested and calibrated using an empirical river model for SPM and validated (blind‐tested) using data from seven European sites. This modelling gives mean monthly SPM concentrations in water for defined river sites. The model is based on processes in the entire upstream river stretch (and not for given river segments) and calculates the transport of SPM from land to water, primary production of SPM (within the upstream river stretch), resuspension, mineralization and retention of SPM in the upstream river stretch (but not bed load of friction materials, such as sand). The catchment area is differentiated into inflow (～ dry land) areas and outflow area (～ wetland areas dominated by relatively fast horizontal SPM‐fluxes). The model is simple to apply in practice as all driving variables may be accessed readily from maps. The driving variables are: latitude, altitude, continentality, catchment area and mean annual precipitation. Results Modelled values have been compared to independent empirical data from sites covering a relatively wide domain (catchment areas from 93 to 5250 km², precipitation from 400 to 660 mm year^?1, altitudes from ?210 to 150 m a.s.l., latitudes from 47 to 59° N and continentalities from 200 to 1000 km from the ocean). When blind‐tested, the model predicts annual SPM‐fluxes well. Conclusion When modelled values are compared to empirical data, the slope is almost perfect (1.03) and the r²‐value is 0.9996. This is good, given the fact that there are several simplifications in the model structure. It must, however, be stressed that there are only seven validation cases and that this model has not been tested for small catchments.     

SIZE-ASSORTATIVE MATING IN A NATURAL POPULATION OF VIVIPARUS ATER (GASTROPODA: PROSOBRANCHIA) IN LAKE ZURICH, SWITZERLAND

The number of mating pairs, the size of the mating partners,and the distribution of individuals of Vivi-parus ater on agrid in Lake Zürich were recorded during one breeding seasonin 1990. There was positive assortative mating with respectto shell size. The proportion of copulating individuals rangedfrom 1% to 6% (average 3%) of the active population at any onetime. Individual snails copulated 60 times on average from Apriluntil November. Snails were abundant and copulated in shallowwater close to the shore in Spring. They moved towards deeperareas in Autumn. V. ater copulated on all substrates at anydepth (1–9 m)of the grid. The spatial distribution ofcopulations throughout the summer reflected the pattern of snailabundance. (Received 29 January 1993; accepted 14 November 1994)     

Overwintering of Microcystis aeruginosa Kutz. in a shallow lake

The standing crop and photosynthetic activity of Microcystisaeruginosa Kütz. in both the plankton and sediment wereinvestigated from November 1979 to May 1982 in Lake Kasumigaura,Japan. The number of planktonic colonies of this species decreasedfrom early autumn to early spring, but increased in the sedimentduring late summer and autumn. The overwintering colonies inthe sediment were –100–1000 times greater per unitarea than those in lake water. No photoinhibition of photosynthesiscould be observed in overwintering Microcystis. The values ofthe initial slopes of photosynthesis-light (P-I) curves weresimilar to those of the summer population, although the maximumphotosynthetic rate (P_max) measured at 20°C was lower thanthat of the summer planktonic population. In winter the valuesof initial slope of the P-I curve, and the ratio of phycobilinto chlorophyll a sorted from sediment were higher than in coloniesfrom the plankton.     

Distribution patterns of nutrients and symptoms of eutrophication in the Rio de la Plata River Estuary System

In this paper we discuss nutrient dynamics and the effects of eutrophication in the Rio de la Plata River Estuary System since 1980. The tidal river was characterized by high suspended particulate matter (SPM), nutrients, and N:P ratio (>25), moderate chlorophyll a values, an inverse relationship between SPM and phosphate, and cianobacteria blooms. Seaward of the salinity front, where both SPM and nutrient concentrations are lower and chlorophyll a values greater, the net ecosystem metabolism is positive. Permanent stratification controls nutrient, organic matter and oxygen dynamics leading to biological stress and hypoxia below the halocline. Non conservative behavior of nitrogen in the estuary leads to a low N:P ratio (<3) because of both phytoplankton assimilation of nitrogen and denitrification, and benthic flux of phosphate. Periodic nuisance and toxic blooms occur at high salinities along the Uruguayan coast (Canal Oriental). Over the recent decades, changes in freshwater inflow, point and non-point nutrient load, and stratification, triggered by ENSO events, seem to have controlled the ecosystem metabolism, nutrient-oxygen dynamics, and the development of harmful blooms. The assessment of the regional and overall ranking of eutrophic conditions determines that the system is moderately eutrophied. Nevertheless, increasing trends in quantity of freshwater and nutrient loads, and the low potential to dilute and flush nutrients, suggest that the Rio de la Plata, in particular the Canal Oriental is prone to worsening eutrophication conditions like oxygen stress and harmful blooms.     

Fish behavioural responses to river discharge trends and the importance of habitat connectivity

Population behaviours associated with the migrations of coarse (non‐salmonid) fishes within river basins are amongst the most poorly understood dispersion mechanisms of temperate freshwater organisms, which in rivers are expected to be influenced by river discharge. We examined the timing and intensity of fish movements (via trapping) between the River Avon (Hampshire, England) and a small floodplain tributary, Ibsley Brook, and tested for correlations with trends in river discharge (i.e. mean cm of change in stage during trapping), water temperature and brook water velocity over twelve months in 1999–2000. 0‐group fishes dominated the catches. Intensities of movement between the brook and the river were similar in most months, but seasonal patterns were observed overall and for individual species. Few significant differences in overall numbers of fish were observed between the discharge trends, but many individual species demonstrated differences, mostly as more intense movement under fast rising discharge. Fish numbers in five species were correlated with river discharge trend, and movements in some species were correlated with the rate of temperature change (Δ° C 10 h sampling), and with changes in brook water velocity. Our results suggest daily movements between the river and small tributary brooks are triggered by changes in light intensity and water velocity, whereas seasonal movements of species between the river and brook are driven by changes in river discharge and water temperature, in particular associated with flood events. This study emphasizes the importance of connectivity in river systems, as fish movement between the Avon and its annexes occur under all flow regimes, but especially with rapidly rising discharge.     

Time Lapse Analysis of Root Elongation Rates of Rice and Sorghum During the Day and Night

This paper describes a technique to monitor the root elongationrate (RER) per hour for several days, and variation in RER duringthe day and night. Rice (Oryza sativaL.) and sorghum (SorghumbicolorMoench) were grown in root boxes placed inside a growthchamber set at 25 °C with a 12 h photoperiod. Seminal rootaxes were sandwiched between a transparent acrylic board andfilter paper placed on a loamy sand soil. The roots were photographedunder dim green light using a CCD camera connected to a timelapse video recorder. The environment of the root, includingtemperature, light, nutrient, water and air supply, was controlledprecisely and maintained constant. RER fluctuated hourly insorghum and to a greater extent in rice. Maximum RERs were 1.4to 4.4 times faster than minimum rates. RERs during the dayand night did not differ statistically when temperatures werethe same.Copyright 1998 Annals of Botany Company Oryza sativaL., periodicity, root elongation,Sorghum bicolorMoench, time lapse.     

Quantitative relationship between two reaction centersin the photosynthetic system of blue-green algae

The quantitative relationship between reaction centers I andII was studied with blue-green algae Anabaena cylindrica, Anabaenavariabilis and Anacystis nidulans grown under different lightconditions. The number of reaction centers I was estimated fromthe P700 content and that of reaction centers II, from the O₂yield of repetitive short flashes. Supplementary determinationswere done with three other blue-green algae and one red alga.The maximum number of reaction centers II counted from the O₂yield of repetitive short flashes was markedly smaller thanthe total number of P700 in all algae tested when the algaewere grown under weak light; in the extreme case (Anabaena cylindrica),the ratio was only 0.258?0.015. This ratio became larger andclose to unity when the algae were grown under stronger light.Variation in the number of reaction centers in a single cellsuggested that reaction center I was a variable component. Ourresults indicate that the proportion of the two reaction centersmay markedly vary in blue-green algae depending on the growthconditions (Received November 13, 1978; )     

Further Observations on Light and Spore Discharge in Certain Pyrenomycetes

A ‘spore-clock’ for studying the hourly rate ofspore discharge over a 24-hour period is described. A numberof the experiments reported in this paper have involved theuse of this apparatus. In Sordaria fimicola there is a distinct positive light-dischargereaction in a dark-conditioned culture, the rate of spore dischargeincreasing steeply to a peak 2–3 hours after brief stimulationby bright light. Although darkening a light-conditioned cultureleads to an immediate decrease in the rate of discharge, thereis no evidence of a delayed negative dark-discharge reaction. In S. verruculosa with a 12-hours light: 12-hours dark dailyreëgime, more spores are discharged in the dark than inthe light periods if the intensity of illumination is low. Withhigher light intensity there is no significant difference betweenthe number of spores discharged in light and dark periods. Asin S. fimicola there is a positive light-discharge reaction,the interval between stimulus and maximum response being muchlonger (8–12 hours). When a dark-conditioned culture istransferred to light for 48 hours and then returned to darknessfor a further 48 hours it is apparent that not only is therea positive light-discharge reaction but also a negative dark-dischargeresponse. The ‘plateau’ level of discharge is essentiallythe same in light and darkness. It is confirmed that in Hypoxylon fuscum light inhibits discharge.