Clarence D. McNabb

Nitrogen input, primary productivity and fish yield in fertilized freshwater ponds in Indonesia

Abstract Twelve 0.2-ha ponds in West Java were fertilized weekly with four levels of chicken manure (12.5, 25, 50, and 100 g dry weight/m 2 week −1 ) during a 149-day growout experiment for Nile tilapia ( Oreochromis niloticus ) production. Laboratory leaching experiments for measuring dissolved inorganic nitrogen (DIN) release from chicken manure showed that nitrogen was released as ammonia-N, which was rapidly lost from the manure and leveled off at about 6 mg NH 4 N/g dry weight chicken manure after 4–5 days. Allochthonous DIN input from both chicken manure fertilization and almost daily source-water additions ranged from 0.055 to 0.142 g N/m 2 day −1 . Source water contributed more nitrogen than manure in all but the highest fertilization treatment. Pond averages of net primary productivity (NP) ranged from 0.54 to 2.00 g C/m 2 day −1 , while gross fish yield at harvest ranged from 4.9 to 15.7 kg fresh weight/ha day −1 . Net fish yield (NFY) was linearly correlated to both the dry weight sum of NP and chicken manure fertilization ( r 2 =0.97) and allochthonous DIN input ( r 2 =0.96). Results suggest that Nile tilapia obtained organic carbon from both primary productivity and manure-derived detritus. DIN availability limited algal productivity at a chicken manure fertilization rate of 100 g dry weight/m 2 week −1 when microbial decomposition of manure supplied sufficient CO 2 . Incorporation of allochthonous DIN input into NFY increased significantly from 15.0% at the three lower fertilization rates to 25.4% at the highest loading rate. Using organic fertilizers proportionally rich in phosphorus and carbon relative to nitrogen may maintain this elements limitation of algal productivity. Efficient utilization of DIN input also may minimize total and un-ionized ammonia concentrations. In the absence of deleterious ammonia effects on survival and growth, fish yields can be readily predicted from measurements of nitrogen inputs.

Effects of nutrient availability on primary productivity and fish production in fertilized tropical ponds

Four fish species were grown in earthen ponds for 352 days in three treatments. Reference ponds received no fertilizer, TSP (triple superphosphate) ponds received 5.7 kg P ha−1 month−1 and TSP-urea ponds received 1.4 kg P and 16.6 kg N ha−1 week−1. Net fish production was 437 kg/ha, 1034 kg/ha and 1713 kg/ha in reference, TSP and TSP-urea treatments, respectively. Mean gross primary productivity was 0.09, 0.17 and 0.26 g C m−2 h−1 and mean net productivity was 0.08, 0.12 and 0.21 g C m−2 h−1 for reference, TSP and TSP-urea treatments, respectively. Reference, TSP and TSP-urea treatments had net photosynthesis estimated from dawn to dusk changes of total inorganic carbon of 1.04, 1.48 and 2.41 g C m−2 day−1. Chlorophyll a concentrations were 12.50 mg/m3, 46.71 mg/m3 and 109.18 mg/m3 in reference, TSP and TSP-urea treatments, respectively. Differences between treatments for fish production, algal production and chlorophyll a were significant (P < 0.05) except for net production in reference and TSP treatments. Net fish production was positively correlated to gross and net primary productivity, and chlorophyll a. Analyses of orthophosphate-P revealed that mean concentrations were highest in the TSP treatment (0.033 mg/l) followed by the TSP-urea treatment (0.009 mg/l) and the reference treatment (0.003 mg/l). An inorganic nitrogen to orthophosphate-P ratio of 36 in reference ponds indicated phosphorus limitation relative to nitrogen. A ratio of 2 in TSP ponds indicated nitrogen limitation. A ratio of 44 in TSP-urea ponds suggested phosphorus was limiting. Bioassay tests using the alga Selenastrum capricornutum Printz, supported the above contention by showing higher growth in response to phosphorus enrichment of reference pond water relative to control cultures, response to nitrogen addition in TSP treatment water and response to phosphorus addition in TSP-urea treatment water. Alleviating these limitations on algal productivity by properly designed fertilizing procedures was expected to increase fish yield.

The uptake of boron by Lemna minor

This study characterizes Lemna minor L. as a bio-accumulator of boron relative to other species of aquatic macrophytes. Laboratory experiments using 0.01, 0.11 and 1.01 mg B l−1 indicated that ambient boron was a determining factor in rate of boron accumulation in plant tissue. Field studies showed that the tissue boron concentration of L. minor, growing on the canopy of submerged Ceratophyllum demersum L. and presumably drawing from the same boron supply, was 10–45 times greater than the tissue boron concentration of C. demersum. In this instance, L. minor had a growing season maximum of near 3200 μg B g−1 ash-free dry weight. The laboratory and field data further suggest that growth rate and uptake rate are both important in determining the tissue concentration of boron.

AMMONIA DYNAMICS IN FERTILIZED FISH PONDS STOCKED WITH NILE TILAPIA

Abstract Total ammonia nitrogen pathways in fertilized fish ponds stocked with Nile tilapia Oreochromis niloticus were investigated. Three fertilizer treatments were used in a field experiment in Thailand: weekly application of 500 kg dry chicken manure/ha (1.2 g N/m2), 44 kg dry chicken manure plus 24 kg urea/ha (1.2 g N/m2), and 500 kg dry chicken manure plus 280 kg urea/ha (14.3 g N/m2). Substantial quantities of ammonia were reduced from pond water in each treatment during daylight hours. Ponds lost 36–75% of the average total ammonia that was present in early morning during daylight hours. Losses to the atmosphere (flux) were relatively small, varying from 1–5% of the total diurnal ammonia reductions. Uptake by algae was the most important mechanism for removal of ammonia from pond water. Net primary productivity varied between treatments and increased with the increased availability of inorganic nitrogen. Increasing the total ammonia present in the early morning increased net primary productivity. F...

A comparison of rain-related phosphorus and nitrogen loading from urban, wetland, and agricultural sources

Abstract Comprehensive watershed studies have been conducted for two lakes located in the Lake Michigan drainage system. Studies were conducted from March through October of 1979. During that interval, large differences in storm-related nutrient loading were measured from urban, wetland, and agricultural sources. Eliminating runoff due to melt of the snow pack, it was found that rain-related discharge from the urban area studied was 0.578 kg total-P and 3.688 kg total-N ha −1 of watershed. Rain induced runoff from marshes in the same drainage basin transported 0.023 kg total-P and 0.585 kg total-N ha −1 of catchment. Rainfall of approximately the same amount caused runoff from agricultural land of 0.180 kg total-P and 5.965 kg total-N ha −1 . Algae of both lakes were phosphorus limited; nitrogen was present in excess. Using constants from Nichols-Dillon relationships in the literature regarding phosphorus, phytoplankton biomass, and secchi disc transparencies, the urban input of phosphorus ha −1 of drainage was sufficient to bring 0.96 ha-m of lake water to undesirable algal bloom status. Similarly, march input ha −1 would bring an estimated 0.04 ha-m into bloom. By the same calculation, storm-related agricultural runoff would result in 0.30 ha-m of lake water becoming undesirably rich in algae. Knowing the number of hectares in these types of catchment and the volume available in a particular lake for phytoplankton production, decisions regarding cost-effective treatment of rain-related discharge can be made.

Hatchery techniques for egg and fry production of Clarias batrachus (Linnaeus).

Abstract Egg hatching, and fry growth and survival of the walking catfish, Clarias batrachus (Linnaeus), were investigated under hatchery conditions in West Java, Indonesia. Spawning was environmentally induced in a specialized breeding pond. Gravid females utilized nests containing kakaban, a fibrous matting from local palm trees ( Arenga sp.), which facilitated egg collection. Newly hatched fry fed with Artemia nauplii though day 8 (after hatching), an Artemia /cladoceran mix from days 9 to 16, and cladocerans only from days 17 to 23 resulted in over 90% survival of young from hatched eggs. Other diets examined (rotifers, cladocerans, ground fish meal, and ground Nile tilapia flesh) proved inadequate for fry through day 16. Fry reared in hatchery aquaria for 16 days versus 23 days before introduction into nursery ponds showed no significant differences in mean length, mean weight, or percent survival when harvested at day 58. Suggested guidelines are given for hatchery production of C. batrachus fry and fingerlings.

Predicting concentration of total phosphorus and chlorophyll a in a lake with short hydraulic residence time

The relationship between total phosphorus and chlorophyll a concentration was determined for Skinner Lake, Indiana over an annual cycle in 1978–79. Total nitrogen:total phosphorus ratios in the epilimnion ranged from 19 to 220 suggesting a phosphorus-dependent algal yield in the epilimnion. Approximately 90% of annual TP loading reached the lake via streamflow, and 93% of this entered during snowmelt and spring-overturn periods. At that time incoming water flushed the lake 2.4 times. Atmospheric loading accounted for 1.4% of annual TP load. Internal hypolimnetic TP loading occurred during summer stratification. Mean [chl a] for the ice-free period was 15.15 mg m−3, within the range expected for eutrophic lakes.The 1978–79 data were used in conjuction with the Vollenweider & Kerekes (1980) model to produce a model specific for the Skinner Lake system. The model predicted mean epilimnetic total phosphorus and chlorophyll a concentrations from mean total phosphorus concentration in inlet streams and from lake water residence time during the period of spring overturn and summer stratification. The Skinner-specific model was tested in 1982 and it closely predicted observed mean epilimnetic [TP] and [chl a] during the ice-free period. This study shows that variability in lake models which average data over an annual period can be reduced by considering lake-specific seasonal variation in hydrology and external TP loading.

Antibiotic treatment of lake sediments to determine the effect of fungi on decomposition

Abstract To determine the role of fungi in decomposition, sediment from a eutrophic lake and a bog was treated with antibacterial antibiotics or with antifungal antibiotics. Sediment treated with antibacterial antibiotics showed a decrease in biochemical oxygen demand and a decrease in direct and pour-plate bacterial counts when compared with controls. Sediment treated with antifungal antibiotics showed an increase in biochemical oxygen demand and an increase in pour-plate and direct bacterial counts when compared with controls. Two species of lake fungi inhibited the growth of a mixed culture of lake bacteria on agar plates. The results infer that fungi inhibit the growth of bacteria in aerobic lake sediment.