Spatial Distribution of Dissolved Inorganic Nutrients and Phytoplankton around Kota Kinabalu Wetland, Sabah, Malaysia

Kota Kinabalu Wetland is importantly habited of mangrove, diverse aquatic flora and fauna as well as feeding stop for migratory birds. This wetland is inundated with the tidal flow, as connected with a small river and nearby coastal areas, thus. A study was carried out to determine the spatial distribution of dissolved inorganic nutrients and phytoplankton diversity at Kota Kinabalu (KK) Wetlands. Five stations, in which river mouth of Likas Bay, river channel (two stations) and inundated area (two stations) in KK Wetland were selected for this study. In-situ parameters of water, water for nutrients and phytoplankton samples were collected from May 2019 until October 2019. The highest concentration of nitrate (0.115 mg/L) was recorded at inundated area of wetland (S5) while the lowest nitrate concentration (0.0047 mg/L) was found at river (S3) flowing towards wetland. The concentrations of ammonia (0.2004 to 2.311 mg/L) were recorded relatively higher at every station compared to other dissolved inorganic nutrients (DIN). The concentration of phosphate was determined in the ranges of 0.0089 - 0.0513 mg/L. Nitrate, ammonia and phosphate showed no significant difference (P = 0.737) in terms of DIN concentration at all five sampling stations during the study period. Twenty-four genera of phytoplankton were identified, dominated by diatoms (55.29%), followed by dinoflagellates (24.95%), Chrysophyta (11.15%), Spirotrichea (5.28%) and Cyanophyta (3.33%). Dominating species throughout the study period include Chaetoceros sp., Pseduo-nitzschia sp., and Cylindrotheca closterium, Peridinium quinquecorne and Alexandrium sp. Phytoplankton species compositions were observed the highest in river mouth area in July with the highest density of 12.115 × 104 cells/mL. The study showed that nutrient concentration was insignificant (P = 0.614) in altering the phytoplankton density, as influences with the tidal water.

Effects of temperature and organic and inorganic nutrients on the growth of Chattonella marina (Raphidophyceae)from the Daya Bay,South China Sea

The effects of temperature and different forms of nutrients on Chattonella marina growth have been investigated in strains isolated from the Daya Bay, the South China Sea. The strain of C. marina preferred high temperatures, with an optimal temperature of 25℃, and 18℃ was the minimum for its survival. Higher cell number and growth rate were obtained in high nitrogen and phosphorus concentrations （500 μg/L, 74μg/L） than under nutrient limitation. Nitrogen influenced the growth most, as the specific growth rate and maximum cell density were lower in nitrogen- limited cultures than noted under phosphorus limitation or under limitation from both. C. marina was capable of using many kinds of organic nitrogen sources including L-serine （L-Ser）, glycine （Gly）, alanine （Ala）, L-threonine （L-Thr）, glutamic acid （Glu） and urea, but could not utilize uric acid. Various forms of organic phosphorus compound such as glucose-6-phosphate （G6P）, sodium glycerophosphate （GYP）, adenosine triphosphate （ATP）, adenosine monophosphate （AMP）, cyti- dine monophosphate （CMP）, guanosine monophosphate （GMP）, uridine monophosphate （UMP）, 4-nitrophenylphosphate （NPP） and triethyl phosphate （TEP） supported the growth as well. Algal cells had the ability to sustain growth under nitrogenand/or phosphorus-free conditions particularly under phosphorus depleted condition. These results led to the hypothesis that high loading of nitrogen has played an important role in frequent C. marina blooms in the past decade, and its capability for utilization of diverse forms of organic nutrients and growth in low nutrient conditions make this species a likely recurrent dominant in the Daya Bay phytoplankton assemblages, visible as more frequent blooms.

Effects of inorganic nutrients and environmental factors on the removal of n-propylbenzene and isopropylbenzene in seawater by cryptophytes Rhinomonas reticulata S6A

To effectively remove n-propylbenzene(n-PBZ)and isopropylbenzene(i-PBZ)leaked into seawater using Rhinomonas reticulata S6A(a newly isolated marine microalga),the effects of three inorganic nutrients and four environmental factors on their degradation were determined after 7 d of inoculation.Results show that NaNO_(3) at 300 mg/L caused a higher removal efficiency of both n-PBZ and i-PBZ(44.79%and 39.26%),while for NaH_(2) PO_(4)·H_(2) O,greater removal rates of two PBZs(47.30%and 42.23%)were achieved at 30 and 20 mg/L,respectively.NaHCO_(3) supplementation(500-750 mg/L)resulted in a large reduction(43.67%-45.04%)in i-PBZ concentration.The change in seawater pH(from 6 to 9)did not affect the elimination of n-PBZ and i-PBZ.The most suitable salinity and temperature were 30 and 25-30℃,respectively,leading to the PBZs removal of~40%.Light intensity exhibited significant influence on elimination of PBZs,and the maximum removal efficiencies of 56.07%(n-PBZ)and 55.00%(i-PBZ)were recorded under 200 and 600μmol/(m^(2)·s),respectively.In addition,the microalga could still remove PBZs when it failed to grow well due to darkness,strong light,low temperature,or low salinity,which might mean that good growth of alga is not always a necessary condition for PBZs removal.Therefore,attention should be paid to the suitability of nutrient levels and environmental conditions(excluding pH)in seawater when using microalgae for bioremediating PBZs-contaminated seawater.

Influence of the Storage Duration at Different Temperatures on the Concentrations of Extractable Inorganic Soil Nutrients

The influence of the short storage periods at different temperatures on the concentrations of extractable soil cations (Ca2+, Mg2+, Na+ and K+) and anions (Cl-, SO4- and PO4- ) has been investigated in nine soil samples from Nile river terraces at River Nile State, North of Sudan (17.82289 to 17.82389N and 33.99974 to 34.02127E). Each soil extract is divided into three treatments: i) control (immediately analyzed);ii) storage for 10 days and;iii) storage for 30 days. Each treatment is replicated three times: i) storage at 10°C;ii) storage at ambient laboratory temperature (25°C) and;iii) storage at 45°C in incubator. Statistical analysis of results reveals that significant difference are found at level (P - and PO4- (0.043, 0.002, 0.001, 0.021, 0.004 and 0.001) respectively at 25°C and 45°C and storage periods of 10 and 30 days. In contrast, significant difference is also found at level (P - concentrations are significantly decreased when the storage period exceeds 10 days and temperature more than 25°C. Depending upon our study results;we conclude that, all extractable inorganic nutrients are clearly affected by storage periods at various temperatures, exception of Na+. Most cations and anions are increased significantly with increased of storage period and temperatures. We therefore highly recommend that the extractable inorganic soil nutrients should be rapidly analyzed in order to obtain accurate results;otherwise, the time between extraction and analysis should be carefully recorded which may help considerably interpreting data from various studies.

Phytoplankton community from Lake Taihu,China,has dissimilar responses to inorganic and organic nutrients

To evaluate the response of phytoplankton from Lake Taihu to different types of nutrients, the phytoplankton responses were measured after adding inorganic nitrogen （N） and phosphorus （P） or decomposed algal scum （Microcystis spp.） into the lake water. Both types of nutrients promoted an increase in phytoplankton biomass as determined by chlorophyll a and algal wet weight. The addition of decomposed algal scum resulted in a significantly greater phytoplankton response than the addition of inorganic N and P alone. The dissolved inorganic N and P in the inorganic nutrient treatment were found not limit phytoplankton growth. The higher algal biomass obtained in the treatment with decomposed algal scum indicated the importance of other organic nutrients besides N and P such as trace elements, as well as the importance of the form of N since the levels of ammonia nitrogen （NH4^＋-N） from the decomposed algal treatment were actually higher than that of the inorganic N and P addition. Microcystis spp. （Cyanobacteria）, Scenedesmus spp. （Chlorophyta） and Synechocystis spp. （Cyanobacteria） were the dominant taxa in the control, inorganic N and P treatment, and the decomposed algal scum treatment, respectively. Microcystis never bloomed in response to both types of nutrient additions indicating that the bloom propagation is not solely related to nutrient additions, but may be related to the absence of selective grazing from zooplankton.