Showing papers on "Productivity (ecology) published in 1971"

Primary Productivity, Chemo-organotrophy, and Nutritional Interactions of Epiphytic Algae and Bacteria on Macrophytes in the Littoral of a Lake

Abstract: Epiphytic algal and bacterial in situ community metabolism and physiological—nutritional relationships of macrophyte—epiphyte systems were investigated in the littoral zone of a small temperate lake from April 1968 through May 1969. Annual primary productivity, chemo—organotrophy of dissolved organic compounds, and field and laboratory studies of macrophyte—epiphyte interactions were monitored by carbon—14 techniques. Productivity measurements of epiphytic algae on artificial substrates colonized in emergent (Scirpus acutus Muhl.) and submergent (Najas flexilis L. and Chara spp.) macrophytic vegetation sites were compared over an annual period with pigment (corrected chlorophyll a and total plant carotenoids) estimates of biomass. Changes in biomass are not proportional to changes in photosynthetic activity, except during periods of intense productivity. The mean daily productivity of epiphytic algae was higher per unit macrophyte surface area of emergent plants (336 mg C m—2 day—1) than on submerged plants (258 mg C m—2 day—1). Mean daily productivity per unit area of the littoral zone, for all of the macrophytic surface area colonized, was 195 and 1,807 mg C m—2 day—1 in the Scirpus and Najas—Chara dominated sites, respectively. The total annual production by algal epiphytes in the Scirpus and Najas—Chara dominated sites was 2.86 and 35.00 g C m—2 of lake surface year—1, respectively. Estimates of annual net production of macrophytes and epipelic algae, derived from studies undertaken during the same time period as reported in this study, indicate that epiphytic algae were responsible for 31.3% of the total littoral production. The epiphytic algae were responsible for 21.4% of the total annual production for the whole lake when the production of the pelagial phytoplankton was added to that of the littoral communities. In comparison to the pelagial phytoplankton alone, the algal epiphytes fixed an amount of carbon equivalent to 75% of the phytoplankton production over the annual period. These results indicate that algal epiphytes on submerged macrophytes may be one of the dominant primary producers in shallow—water ecosystems and may be comparable to the phytoplankton. Deposition of 14C—monocarbonates during in situ productivity measurements represented 38.5—71.7% of the total intracellular fixed carbon. Acidification of 14C—productivity samples by rinsing with dilute hydrochloric acid (0.001 N) removed 24% of previously incorporated carbon and is not recommended as a routine procedure. Physiological interactions in macrophyte—epiphyte systems were investigated by bioassay procedure. Inorganic iron added at less than 10 mg liter —1, and at 100 mg liter—1 in combination with organic compounds of chelatory or complexing ability, stimulated photosynthesis of epiphytic algae. Bioassay experiments in which vitamins, trace metals, and inorganic phosphorus were added to algal photosynthesis. Chlorophyll a, corrected for pheopigment degradation products, and total plant carotenoid levels are among the highest standing crops reported in the literature (annual maximum of chlorophyll a = 7.3 g m—2; plant carotenoids = 40.7 SPU m—2). Maximum concentrations were found during winter under ice cover. Epiphytic bacterial chemo—organotrophy with glucose and acetate substrates was measured at concentrations of 11—160 mg liter—1 and evaluated through Michaelis—Menten enzyme kinetic analysis. First—order active transport kinetics dominated throughout the annual period. Uptake of acetate (submerged plant site, mean rate = 893 mg liter—1 hr—1 dm—2; emergent plant site, 106 mg liter—1 hr—1 dm—2) was greater than that of glucose (submerged plant site, 586 mg liter—1 hr—1 dm—2; emergent plant site, 54 mg liter—1 hr—1 dm—2). Scirpus acutus was labeled in situ during photosynthesis with natural concentrations of carbon dioxide (as 14C). Epiphytic uptake of 14C—labeled, extracellular products of macrophytic origin was determined. Extracellular release of 14C—labeled organic matter was followed at various depths in the littoral water column. The nature of the extracellular release and the amount of 14C fixed by the macrophyte and transferred into the epiphytic complex suggests nutritional interactions that may be prevalent in other macrophyte—epiphyte systems. Najas flexilis, germinated and grown under axenic conditions in a defined medium, was labeled during photosynthesis and placed into the center section of Plexiglas chambers separated by membrane filters free of organic carbon contamination. Over a 3.75—hr incubation interval, a mean of 7% of the total intracellularly fixed carbon was excreted as 14C—labeled dissolved organic carbon. Cultured algal and bacterial epiphytes, separately and mixed in simulated natural communities, were able to utilize these extracellular products when placed into chamber sections adjoining the labeled Najas. The amount of extracellular products utilized by the mixed algal and bacterial communities changed with time, depending on the composition of the epiphytic community. The results suggest interspecific interactions where competition for specific external metabolites or organic solutes may have existed, or where toxic extracellular products may have accumulated. Laboratory uptake of low concentrations of glucose and acetate—14C at 5°, 11° to 12°, and 21° to 23° C by separate and mixed cultures of algal and bacterial epiphytes showed that uptake was strongly influenced by temperature, except at low temperatures where transport and diffusion mechanisms seemed to be inactivated. A sessile bacterium, Caulobacter, however, showed a highly efficient uptake system for both substrates under cold conditions. Uptake of both substrates by mixed cultures of algae and bacteria showed that bacterial uptake of both substrates by mixed cultures of algae and bacteria showed that bacterial uptake was little influenced at low substrate concentrations by the presence of algae. Epiphytic algal uptake following kinetics of simple diffusion was, however, increased in the presence of bacteria, suggesting uptake of 14CO2 previously respired by the bacteria. Macrophyte—epiphyte metabolism may be an important source of dissolved organic materials and extracellular metabolites and thus may help to sustain high levels of primary productivity and chemo—organotrophy in lakes.

The relative importance of nannoplankton and netplankton as primary producers in tropical oceanic and neritic phytoplankton communities1

Abstract: Nannoplankton and netplankton primary productivity and standing crop were measured in a wide variety of neritic and oceanic environments in the eastern tropical Pacific and Caribbean region. Nannoplankters were the most important producers in all the environments studied, but netplankton productivity was significantly (P = 0.05) higher in neritic than in oceanic waters. Mean neritic netplankton–nannoplankton productivity and chlorophyll ratios were 0.50 ± 0.14 and 0.62 ± 0.22 respectively, significantly higher than those observed in oceanic waters. Relative levels of netplankton standing crop and productivity were not systematically related to corresponding levels of primary productivity and standing crop as a whole. The patterns of variation in the relative importance of netplankton and nannoplankton could be accounted for by the high netplankton growth rates and low grazing pressure indices observed in neritic as compared to oceanic waters.

Distribution, production and role of aquatic macrophytes in a southern Michigan marl lake

Abstract: Summary A typical marl lake of the Upper Great Lakes region has very few quantitatively important aquatic macrophytes. The macrophytes, however, dominate the total primary production of the lake. Submersed vegetation is extremely sparse on the shallow (less than I m) marl bench that characterizes the littoral of these lakes, and is completely dominated by one. little-known species (Scirpus subterminalis Torr.) between 1 and 7 m. A detailed investigation of the spatial and seasonal distribution of macrophytic species and biomass showed that S. subterminalis strongly dominated the lake (79% of total biomass). S. suhterminalis represented an almost pure stand (to 200 g m−2 mean annual ash-free dry weight) at all times of the year at intermediate depths of macrophytic growth (1–6 m). Two species of Chara (of eight varieties and forms) were present in significant quantities (12% of total biomass; to 100 g m−2) but were severely limited to shallow depths (0-S-l m) and protected areas. Several annual submersed angiosperms were present (9% of total biomass), but only two species were quantitatively important. Potamogeton illinoensis Morong. and P. praelongus Wulfen formed brief summer peaks (less than 100 g m−2) at 3 and 4–6 m, respectively. A striking feature of the seasonal biomass distribution of Scirpus subterminalis was the higher, viable biomass (to 150g m−2) throughout the winter under ice cover. Cyclic fluctuations of the S. subterminalis populations were discerned at different depths, each with different periodicities. The population at 2 m exhibited a fall peak; that at 4 m had a summer maximum. The lowest overall biomass of S. subterminalis occurred in the 2 m population in June. Chara populations at 0–2 m also exhibited a relatively constant biomass throughout the year. The appearance of Nitella at 7 m in July-October and of Chara at 5 m in September-October was interpreted as an interaction between light, thermal, and carbon stratification. Estimates of macrophytic productivity of perennial (‘evergreen’) species populations whose biomass remains relatively constant throughout the year were made employing several different methods of calculation and turnover factors. All methods resulted in productivity estimates in good agreement with the conservative value of 178 g m−2 year−1 for the entire lake. In comparison to the other components (phyto-planktonic, epiphytic and epipelic algae) of the primary production of Lawrence Lake, the aquatic macrophytes constituted a major portion (anuual mean 82·77 g C m−2 year−1 or 48·3 %) of the total production of the lake. The low diversity but relatively high quantitative importance of macrophytes in marl lakes is attributed to an adverse dissolved inorganic and organic chemical milieu which inhibits phytoplanktonic production and allows only certain adapted macrophytes to develop strongly. The phenomenon of perennial biomass levels throughout the year is believed to be much more common than previously suspected and has iikely resulted from adaptations of submersed macrophytes to ameliorated conditions of water and temperatures relative to the terrestrial situation in winter.

Phytoplankton kinetics in a subtropical estuary: eutrophication1

Abstract: On each of a 4-month series of weekly cruises in Kaneohe Bay, Oahu, Hawaii, in vivo chlorophyll a was monitored continuously by fluorometry, and at 8 stations discrete measurements of chlorophyll a (trichromatic method), primary productivity (14C), and nutrients (nitrate and phosphate) were made. The results are compared with similar data collected a decade earlier in the bay to investigate the enrichment effects of increased waste discharge over this period. The south sector of the bay, site of two sewage outfalls, showed the greatest population instability and had the highest concentrations of chlorophyll a, nitrate, and phosphate, as well as the highest primary productivity. Chlorophyll, nutrient concentration, and primary productivity decreased through the transition sector into the north sector of the bay, which is farthest removed from the waste discharge points. The productivity index (mg C fixed hr−1 mg Chl a−1) showed no such south to north differences. A model of a simplified food chain using a hyperbolic relationship between uptake rate and substrate concentration is postulated to explain the dynamics of the plankton community in the bay.

Relationships between production, nutrient accumulation, and chlorophyll synthesis in an Eleochavis quadvangulata population

Abstract: Maximum standing crop in an EleocJzaris qrradrangulata population was estimated at 881 g dry'~t./m2. Net daily productivity was highest during May when about 50% of the total standing crop was produced. Net productivity for the entire period of vegetative increase, April 1 to August 4, was 7.0 g/m2 per day. The accumulation of several nutrients, especially nitrogen, phosphorus, and potassium was proportionately more rapid than dry matter production during early spring growth. Net chlorophyll synthesis was also greater during early spring. Patterns of change in dry matter and chemical substances in the E. qlradrangulata population were similar to those in populations of other emergent aquatic macrophytes.

Seasonal Variation in Primary Productivity in Three Tropical Ponds

Abstract: Primary productivity values ranged from 1.5 to 15.8 gc/M2/day in Othakadai pond; 2.0 to 8.0 gc/M2/day in Teppakulam tank and 1.05 to 5.4 gc/M2/day in Yanamalai pond. Among the three ponds, highest annual yield was recorded in Othakadai pond (2000.2 gc/M2/yr) next in order comes Teppakulam tank (1211.8 gc/M2/yr) and lastly Yanamalai pond (810.7 gc/M2/yr). In all three ponds temperature and chlorophyll-a showed a more or less direct correlation to productivity values. Alkalinity values and productivity values showed a positive correlation in Othakadai and Yanamalai ponds, while no relationship between alkalinity and productivity could be established in Teppakulam tank.

Species and individual productivity in phytoplankton communities.

Abstract: The relative productivity of individual cells in a mixed phytoplankton community has been determined by (14)C autoradiography. These data allow the estimation of the relative contribution of each of the component species to total community production, illustrate the size—specific production of the cells of each of these species, and suggest predictions concerning future successional developments of the community. See full-text article at JSTOR

The distribution and net productivity of sublittoral populations of attached macrophytic algae in an estuary on the Atlantic coast of Spain

Abstract: A short term study was made on the ecology and the net productivity of sublittoral populations of benthic macrophytes in, and near, the Ria de Aldan on the Atlantic coast of Spain. A preliminary survery was made using SCUBA diving techniques and this revealed that the most extensive sublittoral communities were those dominated by Laminaria ochroleuca and/or Saccorhiza polyschides. The effect of depth and the amount and type of water movement on the distribution and productivity of these two populations was studied at 7 localities. There was found to be a narrow zone of transition between the two populations and the depth of this zone was governed by the amount of water movement. The factors which might control the dynamic equilibrium between these two populations are discussed. The total standing crop and productivity per unit area was found to undergo a decrease with both an increase in depth and wave action whilst the highest values of all were in two localities where there was considerable current surge. The maximum productivity of L. ochroleuca (17 metric tons/hectare/annum) was found in the most sheltered locality studied, whilst the highest value for S. polyschides (39 metric tons/hectare/annum) was found where the current surge was greatest but wave action was only moderate. This maximum value for S. polyschides is the highest yet reported for naturally occurring beds of submerged seaweeds. Figures for the net efficiency of energy fixation are presented and discussed.

A Study of Phytoplankton Dynamics in Lake Fayetteville as a Means of Assessing Water Quality

Abstract: ......................................................................................................................... V Introduction ................................................................... . ................................. . 1 Materials and Methods .............................................................................................. 4 Results ............................................................................................................................... 6 Discussion ...................................................................... .....................................................46 Literature Cited........................................................ ....................................................56

Standing crops and primary productivity of the epipelon of two small ponds in North Somerset, U. K.

Abstract: The primary productivity and the standing crop of the epipelic algal communities in two small ponds of contrasting nutrient status were measured over a 2 year period. Standing crops reflected the richer nutrient status of the eutrophic Abbot's Pond compared with the oligotrophic Priddy Pool as did the productivity results when the same depth category in both ponds was examined. Production resulted from an interrelationship among light intensity, standing crop size and other variable environmental factors in both pools, however light in Abbot's Pond appeared to be the most important factor in limiting standing crop size and production in the deeper depth categories.

Primary production in the mid-subarctic pacific region, 1966-68

Abstract: Primary productivity, chlorophyll a, net zooplankton, nutrients, and associated physical variables were measured on seven cruises in the mid-Subarctic Pacific Region in 1966-68. Most of the data were col­ lected between lat 46° N and the central Aleutian Islands, although several measurements were made as far south as lat 40° N. Primary productivity and chlorophyll were higher in Aleutian coastal waters than in areas to the south, but no other major differences among upper zone domains were consistent seasonally. Production was low in winter, high in spring. and intermediate throughout the summer. Annual productivity was between 80 and 100 g C/m2• Chlorophyll a concentrations changed only slightly except in March when chlorophyll was high during the early part of the phytoplankton bloom. Low light intensities limited primary production during the winter, and zooplankton grazing appeared to limit production in summer and part of spring. Nutrients and light were always sufficient to sup­ port high productivity during spring and summer except in late summer when some nutrients, particu­ larly nitrate, were very low south of lat 44 0 N; however, the productivity did not appear severely limited. The main source of phosphate replenishment in the upper layers during spring and summer was probably in situ regeneration by zooplankton rather than upwelled deep water. The pelagic biota of the Subarctic Pacific Region has long been recognized as distinct from that in the Subtropical Region, and the Subarctic is thought to be generally more productive. Until the introduction of the carbon-14 technique by Steemann Nielsen (1952), however, no adequate means existed for directly measuring primary productivity in the open ocean. Since that time thousands of measurements of primary produc­ tion have been made throughout the Tropical and Subtropical North Pacific. Measurements in the Subarctic Pacific have been fewer and more localized. Koblents-Mishke (1965), who summarized data from the Pacific Ocean, estimated that pri­ mary productivity in the mid-Subarctic Region averaged about 150 to 250 mg C/m 2 per day or 55 to 91 g C/m 2 per year. She estimated average production in the Gulf of Alaska and along the Washington and Oregon coasts to be between 250 and 650 mg C/m 2 per day (90-240 g C/m 2 per year) and in the transition area of the southern Subarctic to be 100 to 150 mg C/m 2

Interrelationships between site factors and productivity of radiata pine at Riverhead Forest, New Zealand

Abstract: Significant simple correlations were found between productivity of radiata pine growing on known P-deficient soils and available soil P, mycorrhizae, slope, aspect, pH, and drainage. However, partial and multiple correlations showed that available soil P, mycorrhizae, fine sand, clay and slope were the only measured variables to make a significant independent contribution towards explaining variation in productivity. Aspect and pH were found to be related to productivity indirectly through their interrelationship with available soil P, and drainage indirectly through its interrelationship with mycorrhizae. The failure of clay and fine sand to show a significant simple correlation with productivity despite contributing independently to variation in productivity was attributed to their effects being more pronounced within specific levels of other variables than over their complete range.

Net primary productivity of bog vegetation in southeastern Manitoba

Abstract: The net primary productivity of bog vegetation was determined for a peatland site located in south-eastern Manitoba. The productivity of non-vascular species (55.4 g/m2 per year) was small compared...

Influence of photoperiod and water supply production of seed and dry matter in three varieties of soybean, Glycine max (L.) Merr

Abstract: In glasshouse experiments soyabeans cv. Improved Pelican, L.Z. and Pennsoy were grown at 30/20 deg C day/night temperatures and under the prevailing natural photoperiod (16.2, 14.2 and 12.7 h in July, Aug. and Sept., respectively) or a controlled 12-h photoperiod. Plants were given 25, 50, 75 or 100% of a standard water application. In a further laboratory experiment, rates of photosynthesis and transpiration were determined under different light intensities. DM production, seed production, water consumption and the rate of photosynthesis did not differ between cv. and there was a rectilinear relationship between seed production and DM production and between DM production and water consumption. Plants given a >12-h daylength did not flower. In the controlled 12-h daylength, productivity/unit of water consumption was smaller than in the prevailing daylength. The rate of photosynthesis was somewhat lower than the rate presented by de Wit for most agricultural crops and the relationship between the rate of photosynthesis and transpiration was curvilinear for short periods. (Abstract retrieved from CAB Abstracts by CABI’s permission)