Showing papers on "Productivity (ecology) published in 1980"

Productivity, sedimentation rate and sedimentary organic matter in the oceans II-Elemental fractionation

Abstract: The vertical flux of biogenous organic matter to the sediment surface is a function of water depth and primary productivity; this relationship can be expressed empirically as: (1) org-Cflux = 5.9 · depth-0 616 · productivity Upon descent through the water column and prior to burial, biogenous detrital organic matter undergoes strong elemental fractionation by preferential removal of nitrogenous and P-containing organic compounds. At the water-sediment interface, a portion of the detritus is converted into biomass by benthic organisms, which concentrate nitrogen and phosphorus relative to carbon. These two processes are reflected in the elemental composition of sedimentary organic matter. A third process concentrates organic matter in sediments by sorption onto clays. This sorbed material is high in organic-N and devoid of organic-P; its relative abundance is high only in pelagic clays. The concentrations of each of the three forms of organic matter -detrital, biomass, and sorbed- can be calculated from the following expressions: (2) org-Csorb = 0.005 · Al2O3 (3) org-Cdetr = org-Ctota1 – org-Csorb - e · org-Ntotal / 1-2/f (4) org-Cbiom = org-Ctotal - org-Cdetr - org-Csorb where e and f are the C/N elemental weight ratios of biomass and detritus respectively

Hypolimnion Oxygen Consumption in Lakes: Discussion of Productivity and Morphometry Effects

Abstract: Until recently, hypolimnion oxygen consumption was thought to be a way of comparing the productivity of lakes. This study shows that hypolimnion oxygen represents hypolimnion thickness and temperat...

The chemistry, biology, and vertical flux of particulate matter from the upper 1500 m of the Panama Basin☆

Abstract: Particulate matter divided into 53- μ m size fractions was obtained using the Large Volume in situ Filtration System (LVFS) modified to collect four samples per deployment. Samples collected to 1500 m at 0°45′N, 86°10′W were analyzed for major and minor element, organism (species assemblage and population densities), and large particle size distributions. Vertical fluxes of fecal matter, fecal pellets, Foraminifera, and diatoms were calculated from size distribution data and two settling models. Estimates of the vertical mass, organic carbon, carbonate, and opal fluxes were compared with mean particle collection rates by sediment traps deployed at 2500 m for 234 days commencing at the time of LVFS sampling. The productivity of the surface layer at this station is controlled by the north-south position of the Equatorial Front, which separates low productivity Tropical Surface Water (TSW) from a mixture of warm Subtropical Surface Water (SSW) and cool, nutrient-rich water upwelled along the Peruvian coast. At the time of LVFS sampling the front was south of the station, with the lower productivity TSW dominating the surface water. Particle distributions and fluxes indicated lower than average productivity and highly efficient zooplankton grazing. Variability in productivity at the station was indicated by weekly sea surface temperature data and was manifested by an anomalous centrate diatom maximum centered at 400 m and by the indication that the particle flux through 1500 m was 1/40th of the rates particles were collected by the sediment traps at 2500 m. The depth of the nitrite maximum corresponded to that of strongest rate of decrease of the organic carbon flux. Fluxes of particulate opal and carbonate decreased markedly in the upper water column although it was supersaturated with respect to calcite. The occurrence of fecal pellets devoid of birefringent material in the water column indicates that the carbonate dissolution was biologically mediated. Calculations indicate that the strong carbonate dissolution in the upper waters at this station is not representative of “average” ocean conditions and is probably a local or rare phenomenon.

Ecological Effects of Waste Water

Abstract: Part I. General Concepts of Aquatic Ecology: 1. Aquatic ecosystems and management 2. Standing crop and productivity 3. Hydrographic characteristics 4. Population growth 5. Limitation, tolerance, and adaptation 6. Nutrient cycles Part II. The Effect of Waste on Populations: 7. Phytoplankton and controlling factors 8. Zooplankton 9. Periphyton 10. Macrophytes 11. Benthic macroinvertebrates 12. Fish Appendices Index.

Fish community structure and function in terminos lagoon a tropical estuary in the southern gulf of mexico

Abstract: A total of 21,734 fish from 121 species was taken in 173 collections from July 1976 to March 1979. Seventeen species had a broad distribution and comprised 82% of total numbers. Twelve species (10%) were thought to be permanent residents, 54 (45%) probably used the lagoon as a nursery or feeding ground or both, and 55 (45%) were occasional visitors. Twenty-two percent were herbivores, detritivores, or omnivores, 51% were second order consumers, and 27% were higher consumers. Clustering was used to construct a dendrogram of faunal similarity; it corresponded to major differences in the physical makeup of the lagoon and demarcated southern and northern shore groups of fish. There is an apparent pattern of migration within the lagoon reflecting prevailing currents. The season of maximum juvenile influx from the sea (Aug. to Oct.) was during maximum river flow. Diversity indices (H′, D, J′) reflected changes in numbers of species and individuals during the year, and some were highly correlated with temperature and salinity. Biomass at different sampling stations ranged from 0.95 to 11.3 g wet wt m –2 and H′ ranged from 0.53 to 2.50. Fishery productivity was as high as 12.0 g m –2 year –1 .

Cenozoic biogenic silica sedimentation in the Antarctic Ocean

Abstract: The Antarctic Ocean during Cenozoic time experienced four periods of enhanced siliceous productivity. The beginning of the Miocene and the Pliocene-Quaternary are the two major periods. The Pliocene-Quaternary increase in productivity began 5 m.y. ago and has progressively increased to the present level of intense surface productivity. Two short-lived periods of slightly increased surface productivity were the middle Eocene and the middle Miocene. The major control of Antarctic surface productivity through the Cenozoic has been climate. Climate in the Southern Ocean is ultimately controlled by tectonic changes in the Antarctic Ocean basin, which altered the patterns of surface and thermohaline circulation. Antarctic surface waters became more conducive to siliceous biological productivity with the progressive latitudinal and thermal isolation of Antarctica. Opal production during the Neogene increased particularly during globally cooler times, due to the intensification of upwelling south of the Polar Front. This intensification was caused by accelerated atmospheric circulation and an increased volume production of Antarctic Bottom Water. Since the Oligocene, times of increasing productivity in the Antarctic correspond to periods of decreasing productivity in the central equatorial Pacific Ocean. It appears that high concentrations of limiting nutrients upwelling in the Southern Ocean have enabled the region to successfully “compete” for silica. The efficiency of the biological cycling of silica has progressed to the extent in the Antarctic that much of the silica assimilation and accumulation has transferred to the Antarctic at the expense of other productive oceanic regions such as the central equatorial Pacific.

Life Cycles of Mass Species of Tubificidae (Oligochaeta)

Abstract: The life cycles of mass species of Tubificidae: Isochaetides newaensis, Tubifex tubifex and Limnodrilus hoffmeisteri have been studied in rivers, reservoirs, lakes and under experimental conditions. The length of the life cycles depend on abiotic and biotic factors of the environment. Thus, changes in the temperature regime, in the level of productivity of the mud, and in the population density result in changes in the time, duration, and intensity of reproduction of the worms causing transformations in the structure and productivity of the populations.

Salt marsh productivity with natural and altered tidal circulation.

Abstract: The effects of altered tidal circulation on southern California salt marshes are investigated by comparing a well-flushed wetland and two modified wetlands which have reduced tidal flow. The Tijuana Estuary had continuous exchange of seawater but relatively low net aerial primary productivity (0.4–1.0 kg m-2yr-1) of vascular plants. Low productivity (0.6 kg m-2yr-1) was also found in the Flood Control Channel of the San Diego River, where tidal exchange was restricted to flow through a riprap dike. High productivity (1.2–2.9 kg m-2yr-1) in Los Penasquitos Lagoon was attributed to the influences of freshwater impounded behind a sand bar which blocked the mouth of the lagoon during much of the study period. It is hypothesized that elimination of tidal flow during the growing season increased primary productivity of vascular plants because freshwater runoff decreased soil salinity and because nutrients were retained within the marsh. However, we predict that sand bar obstruction can decrease productivity if below-average rainfall leads to hypersalinity of closed lagoons. Comprehensive evaluation of the effects of altered tidal circulation requires longterm study and examination of the total ecosystem.

Leaf Production During Secondary Succession in Northern Hardwoods

Abstract: Leaf biomass is an important component of forest ecosystems. It is proportional to leaf area and primary production and also contains a major portion of a plants annual nutrient uptake and its contribution, through litter fall, to the forest floor. Thus leaf biomass reflects important developmental differences in both primary production and nutrient cycling between stands. While much information is avaialable for changes in leaf production over time in monospecific stands we know of no similar published data for a mixed-species temperate forest.

Trophic upsurge and the relationship between phytoplankton biomass and productivity in Smallwood Reservoir, Canada

Abstract: The primary productivities of a natural lake, a new reservoir, and an established reservoir were investigated in western Labrador over two seasons. Productivity of the new reservoir was about twice those of the other two sites. Possible causes for this increased productivity were examined. It was found that differences in productivity were due to differences in standing stocks of plankters only, and not due to differing photosynthetic efficiencies, better light, or a combination of these factors. Since changes in biomass may be predicted from changes in phosphorus concentration, these findings support the hypothesis that the increased productivity in new impoundments may be explained by the increase in phosphorus concentration.

Comparison of in situ photosynthetic activity of epiphytic, epipelic and planktonic algal communities in an oligotrophic lake, southern finland1

Abstract: The photosynthetic activity of different algal communities at the outer edge of an Equisetum fluviatile L. stand in an oligotrophic lake (Paajarvi, in southern Finland) was investigated. Production by the algal communities was measured simultaneously using a modified 14C-method, and the results were related to the volume of algae and the available irradiance. The relative production rate (P/B quotient) of phytoplankton was ca. 3 × that of epiphyton and ca. 20 × that of epipelon. Epiphyton productivity remained almost constant although the algal volume varied greatly, suggesting that the surface layer of the algal community was mainly responsible for the photosynthetic activity. In the littoral area (at 1 m depth) primary production/m2 of lake surface by phytoplankton, epiphyton and epipelon was similar but in the littoriprofundal area (2–4 m) phytoplankton production was twice that of epipelon. Primary productivity of epiphyton and epipelon/m2 of substratum was about equal to phytoplankton productivity/m3 of water at the same irradiance. This relation provided a means of estimating the relative contributions of the different algal communities to the total algal production in the lake.

Relationships Between Dipteran Emergence and Phytoplankton Production in the Experimental Lakes Area, Northwestern Ontario

Abstract: Dipteran emergence was monitored at the Experimental Lakes Area (ELA) between 1973 and 1977 in seven lakes of different trophic status. The data were used to develop a number of equations which related the quantity and spatial distribution of average annual emergence to lake productivity. These models explained > 94% of the variation in mean emergent biomass among lakes or > 76% of the variation in numbers of emergent Diptera in terms of phytoplankton production or phosphorus loading. On average, ELA lakes produced 40.8 dipteran adults (9 mg dry weight) per gram carbon fixed by phytoplankton. A single equation for all lakes predicts the surface distribution of emergent biomass, relative to lake depth at any location, from vertical profiles of phytoplankton production. The mean size of dipteran adults was related to lake depth at the point of emergence and average phytoplankton production. An empirical model which used data on the vertical profile, and lake average, of phytoplankton production was develope...

Amount and distribution of dry matter in a mature beech/podocarp community [in New Zealand].

Abstract: The total plant dry matter in a mature beech/podocarp community was estimated at 703 t/ha. The principal species and their above-ground dry matter (d.m.) content (in t/ha) were: Nothofagus truncata (145), N. fusca (36), Podocarpus ferrugineus (25), and Weinmannia racemosa (63); d.m. was distributed among the major components as follows: stem wood (201), stem bark (23), branch wood (50), branch bark (19), dead branches (6.5), and foliage (5.7). Dead standing trees contributed a further 22 t/ha. Together, these aboveground components comprise 47% of the forest d.m. content. The forest floor detrital matter was estimated at 226 t/ha and, when roots were included, 373 t/ha or 53% of the forest d.m. content. Commercial logging extracted 27% of the dry matter as utilisable logs; and of the residual 73%, 36% comprised material already dead and in various stages of decomposition. Regression analysis was used for the trees and shrubs, and unit area harvesting methods for the remaining forest components.

Aquatic macrophyte communities of the wilderness lakes: community structure and associated environmental conditions

Abstract: SUMMARY The structure and summer biomass (g m−2 dry mass) of the principal aquatic macrophyte communities of the Wilderness Lakes were measured. Both emergent and submerged communities were included in the study. Productivity estimates were made by multiplying biomass by production/biomass ratios for each species. Salinity gradients in the system are described and details of the different sediment types associated with the macrophytes are given. There was considerable variation in production rates between the different water bodies often coinciding with a salinity gradient. However, rapid, natural changes in the communities are described which also influence production rates in a given water body. Production rates (g dry mass m−2 a−1) were of the order: Typha latifolia > Phragmites australis > Scirpus littoralis > Potamogeton pectinatus > Chara qlobularis > Ruppia cirrhosa. The significance of the macrophyte rates is discussed in relation to Wilderness Lakes area as a whole.

The effect of zooplankton on phytoplankton productivity in the epilimnion of a subalpine lake

Abstract: The net effect of zooplankton on phytoplankton productivity was investigated through experiments using natural concentrations of plankton in the epilimnion of Castle Lake, California. Zooplankton enhanced algal productivity during July and August, and nocturnal grazers caused greater proportionate increases than did daytime densities. Consumers had neutral or negative effects in September. Animal biomass was associated significantly with enhanced productivity for the experiment in late July, and with decreased growth rates in the last trial of September. The direct relationship between the activities of zooplankton and primary productivity observed in other lakes is qualified by this seasonal change in net effect. The removal of algae by grazing, increases in the productivity to biomass ratio through nutrient regeneration and temporary photosynthetic inhibition from ammonia excretion appear to have shifted in relative impact during the 3 month experimental period.

Productivity of algal epiphytes in a Georgia salt marsh: effect of inundation frequency and implications for total marsh productivity

Abstract: Primary production by algal epiphytes of dead Spartina alterniflora shoots in a Georgia salt marsh was measured using the 14C technique. A 23 factorial design was used to quantify the effects of light intensity and inundation frequency (stem height) on carbon fixation at two sites along a salt marsh creek. Algae inundated daily fixed carbon more rapidly than those which had dried for several days, but this may have been the results of greater biomass on more frequently immersed stems. This result corroborates studies showing desiccation is not always a severe stress for intertidal algae. Similarity of epiphyte algal productivity to that of salt marsh benthic diatoms suggests that, given adequate substrate, the epiphytes may be an important source of primary production during some seasons of the year.

Abundance relationships between competitive and grazing-tolerant plants in productivity gradients on Fennoscandian mountains.

Abstract: According to S. D. Fretwell's general theory of population regulation, relatively low primary productivity is always accompanied by heavy grazing pressure exerted by natural herbivores upon the vegetation. This is reflected in the prevalence of plants that tolerate grazing and the accompanying mechanical disturbance. The abundance relationships of different growth forms in Fennoscandian oroarctic plant communities were examined in relation to this prediction. Although the structure of the vegetation in all the relatively unproductive communities analysed appeared to indicate strong grazing pressure, the kinds of grazing-tolerant plants discussed by Fretwell did not always prevail. As originally formulated, Fretwell's theory appears to deal best with strongly seasonal productivity clines, whereas plant defence appears important in less seasonal ones.

Recent sedimentation and its relationship with primary productivity in four western Washington lakes1

Abstract: Studies of scdimentntion processes in four western Washington lakes reveal up to sixfold variations in sedimentation rates over the past 130 years of settlement in the region. These variations in sedimentation can be linked with known changes in land use in the watersheds, cspccially logging, which appears to have accclcrated erosion. Contemporary deposition of phosphorus into profundal sediments is positively correlated with phytoplankton productivity in the four lakes. If a similar relationship existed in the past when sedimentation rates of phosphorus were different, then increases in primary productivity from twofold to fourfold could have occurred in three of the lakes since about 1840. Cultural activities in a lake’s watershed

Annual productivity and phytoplankton changes between 1969 and 1974 in Gull Lake, Michigan

Abstract: SUMMARY. The seasonal and depth distributions of dominant phytoplankters, in situ primary productivity, organic carbon, and major chemical variables are described for Gull Lake, Michigan for the years 1971–74. Despite efforts by residents surrounding this moderately large dimictic lake to reduce phosphorus loading, all indications are of progressive eutrophication over the period. Previously dominant Cyclotella michiganiana has almost completely disappeared while araphidinean diatoms have increased greatly; certain blue-green algae that were absent previously are becoming characteristic. The ratio of araphidinean to centric diatoms in recent sediments has also increased. Primary productivity and particulate and dissolved organic carbon concentrations have also increased. Voluntary attempts to reduce nutrient loading have apparently been inadequate to arrest increasing rates of eutrophication.

Plant response to Los Angeles Aqueduct construction in the Mojave Desert.

Abstract: Construction of the 1913 Los Angeles aqueduct system had a different effect on vegetation productivity, diversity, and stability in the Mojave Desert than did construction of the 1970 aqueduct. Drastic disturbance was found to impede vegetation recovery, whereas slight disturbance sometimes enhanced vegetation. Comparisons of productivity, diversity, and stability measures for both aqueducts show apparent similarities of vegetation cover, biomass, and density. However, these similarities often vanish when one considers qualitative factors, such as proportion of long-lived species and typical cominants of undisturbed communities. Percentage composition of common long-lived perennials represents a good qualitative measure to supplement quantitative comparisons. Enhancement of vegetation along the right-of-way transects of the 1913 aqueduct shows considerable recovery, owing to the more than 65 years that have passed since construction.

A comparison of epiphytic diatom assemblages on living and dead stems of the common grass Phragmites australis

Abstract: Diatoms epiphytic on Phragmites austmUs (Cav.) Trin. ex Steaded stems were collected from a single clone at the .southern end of Provo Bay, Utah Lake, Utah. Diatom populations from both living and dead stem sections were analyzed. Species diversity in each .sample was high, indicating that the stems provide a relatively stable habitat for diatom epiphytes. Of the 23 genera found, only Gomphonema and \avicula showed significant trends toward stem preference. The diatoms in this study support the current view that Utah Lake is a slightly saline, eutrophic system. The occurrence of diatom assemblages as epiphytes on httoral, emergent macrophytes is well documented (Godward 1934, 1937, Knud.son 1957, Prow.se 1959). Likewise, the impact of such epiphytes on primary productivity and community trophic structure has been examined in several estuarine environments (Mclntire et al. 1971, Stowe et al. 1971, and Main et al. 1974), but has been largely ignored in freshwater systems (Wetzel 1964). Tlie epiphytic diatom communities attached to emergents inevitably play a role in the overall productivity of lakes and estuaries. They also contribute to regulation of the overall metabolism of such waters by altering the amount and quality of allochthonous organics entering the lake by acting as physical and metabolic traps or filters. The attached diatom flora also serves as an autochthonous source of particulate organic and dissolved organic matter that is readily available to pelagic animals. The degree of influence of these epiphytic organisms on the productivity of standing waters has rarely been determined. However, Allen (1971) estimated that up to 31.3 percent of the total littoral production could be attributed to epiphtyic algae, with up to 21.4 percent of the total lake production being attributable to such attached communities. In addition, a comparison between phytoplankton and epiphyte production demonstrated that the latter was equivalent to 75 percent of the phytoplankton production over the annual period (Allen 1971). Even though epiphytic commimities have been demonstrated to be important, the distribution patterns of such assemblages on the basis of variation in ho.st species and host substrate conditions have received little attention. Likewise, the complex physiological relationship between the host macrophyte and the attached diatom species has received less attention than warranted (Wetzel 1964, 1965, 1969b, Allen 1971, Hough et al. 1975). The impact of this relationship is fimdamental to understanding the basic distribution patterns of epiphytes not only on different macrophyte host species but also on members of the same species at different levels of senescence. The purpose of this study is to illuminate distribution patterns of diatom epiphytes on living and dead specimens of a single macrophyte host {Phragmites australis (Cav.) Trin. ex Steaded) in Utah Lake, Utah. The data from this study will be used as a baseline for extended research in Utah Lake on epiphyte distribution patterns and epiphyte impact on lake productivity and trophic structure.