Macrophyte Production Research Articles

Effects of seasonality and plant density on the productivity of some freshwater macrophytes

The primary productivity of the aquatic macrophytes Eichhornia crassipes (Mart.) Solms, Lemma minor L. and Hydrilla verticillata (L.f.) Royle was measured for a complete years to assess the potential yields of these plants in large-scale cultures. Annual productivities of cultivated populations of the three species in central Florida averaged 24,2, 3.7 and 4.2 g dry wt. m −2 d −1, respectively. Productivity of nearby natural stands of Eichhornia and Lemna was about three times lower than that of the cultivated populations. Both productivity and specific growth of the two floating species were strongly dependent on plant density. Optimum stocking densities for Eichhornia and Lemna based on weekly harvests were 1000 and 20 g dry wt. m −2, respectively. Of the three species, Eichhornia was considered to be the most promising for cultivation in such large-scale applications as wastewater treatment.

Growth and primary productivity of marine macrophytes exposed to domestic sewage effluents

This study provides the first response data for ten Southern California macrophytes exposed to untreated, primary, secondary and secondary chlorinated sewage effluent during long-term culture studies in the laboratory as well as short-term metabolic studies in the field and in the laboratory. Bossiella orbigniana, Lithothrix aspergillum and Corallina officinalis var, chilensis had relatively broad homeostatic capabilities and enhanced net production rates when exposed to primary treated sewage. In the long-term cultures, Amphiroa zonata, B. orbigniana and C. officinalis var. chilensis all demonstrated enhanced growth in the presence of primary sewage. Chlorination of effluent had only a short-term negative effect; i.e. species' responses to secondary and secondary chlorinated sewage were virtually identical beyond the second week in culture. Three populations of C. officinalis var. chilensis with differing pollution histories showed a tolerance to sewage corresponding to the extent of previous exposure, indicating that this species may be able to acclimate physiologically to sewage stress. The more sewage-tolerant macrophytes displayed lower photosynthetic quotient values during exposure to effluent than those possessing little tolerance to sewage.

The ecology of Ruppia-dominated communities in western Europe. III. Aspects of production, consumption and decomposition

In this final paper in the series on Ruppia-dominated communities several functional aspects are treated, most attention being paid to the cycle of the macrophyte material.The productivity of the Ruppia stands was studied by regular samplings of the macrophyte biomass and estimations of the annual turnover. Biomass was measured at the moment of the seasonal maximum in a large number of localities in the Camargue, France, in the costal area of The Netherlands and in the coastal archipelago near Tvärminne, Finland. Seasonal maximum biomass of the Ruppia stands proved to be rather similar in the three study areas (mostly around 150 g m−2 ash-free dry weight), whereas the annual turnover rate showed distinct differences between the localities in the Camargue (1.5–2.5) and those in The Netherlands and Finland (1.2–1.4). The productivity of Ruppia is only moderate compared with the productivity of aquatic macrophytes in freshwater and marine habitats.The decline of Ruppia stands as a result of prolonged turbidity brought about by excessive phytoplankton growth was studied in detail in two eutrophicated brackish ponds in The Netherlands. The transparency in these ponds proved to be continually low (10–20 cm Secchi) due to extremely dense phytoplankton populations (0.3–1.7 mg chlorophyll a l−1). The results of an experiment in which Ruppia stands were artificially shaded in clear water suggest that the Ruppia decline in the two turbid ponds is directly caused by shade.The consumption of Ruppia cirrhosa (Petagna) Grande by a dense population of coot (Fulica atra L.) in a brackish pond on Texel, The Netherlands, was quantified in the autumn of 1976. By daily counts of the numbers of feeding birds the number of coot-days could be estimated. Three different methods to determine the amount of R. cirrhosa daily consumed by the coots, i.e., biomass differences between Ruppia stands in exclosures and those in the rest of the pond, feeding experiments in an aviary and theoretical calculations based on the standard metabolic rate, delivered results in the same order of magnitude. Twenty percent of the maximum biomass of Ruppia (100 g m−2) proved to have been consumed by coots in the period September–November. In the Camargue, France, an attempt was made to delimit the feeding grounds of three quantitatively important waterfowl species, the flamingo (Phoenicopterus ruber L.), the wigeon (Anas penelope L.) and the coot. Large numbers of flamingo foraged in R. cirrhosa localities, this species generally consuming invertebrates and seeds. For the wigeon, only the localities used as feeding grounds during the day could be studied; these all proved to be inhabited by Ruppia. However, the wigeon feed intensively by night, and their nocturnal feeding grounds in the Camargue are unknown. There are many indications that the wigeon in the Camargue feeds mainly on R. cirrhosa. Theoretical calculations showed that, for the maintenance of the complete hibernating wigeon population, 1200 ha of Ruppia-covered lagoon would be needed (10% of the area actually covered by R. cirrhosa in the Camargue in 1977). The coot proved to feed mainly in localities inhabited by Potamogeton pectinatus L.The decomposition of R. cirrhosa was studied quantitatively in a field experiment with litter bags. The breakdown of the plant material in the bags took place within one year. Experiments in which amphipod and isopod species were fed with senescent R. cirrhosa showed that Gammarus spp. and Idotea chelipes (Pallas) can consume considerable amounts of dying and dead plant material and that the mineralization is markedly increased when their feeding activity is high.Finally the results of the complete study on Ruppia communities are brought together and discussed. The approach used in this study is critically reviewed and desiderata for further research are given.

Transport of particulate organic material between salt marsh and estuary

The macrophyte production and the transport of particulate organic matter between march and adjacent estuary have been investigated for a 30 ha salt marsh along the Oosterschelde estuary, The Netherlands. The primary production of macrophytes, measured with Smalley's method, was 837–1030 g dry organic matter.m−2.year−1. Measurements of amounts of particulate organic matter transported through one of the main tidal creeks in the salt march resulted in a net import. On average 31% of the material brought in by the flood settled in the marsh. The majority of this material is smaller than 63 μm. On the other hand large floating material is exported during storm tides, although the quantity seems to be smaller than that of the suspended material imported. The differences between various marshes with regard to export and import of organic matter are explained in terms of marsh level, primary production, turbulent diffusion, sinking and resuspension of particulate matter and biotic transformations.

Coexistence and the comparative light relations of the submersed macrophytes Myriophyllum spicatum L. and Vallisneria americana Michx.

The Eurasian watermilfoil (Myriophyllum spicatum L.) has partially replaced wild celery (Vallisneria americana Michx.) as a community dominant in the littoral zones of lakes of Madison, Wisconsin. The two species have very different growth forms, with that of M. spicatum corresponding more closely to the optimal growth form simulated by the macrophyte production model WEED. The objective of this research was to investigate the mechanisms by which Vallisneria could compensate for its nonoptimal growth form and coexist with Myriophyllum.A quantification of midsummer growth form for the two species at a rooting depth of 80-90 cm showed that M. spicatum had 68% of its shoot biomass within 30 cm of the surface, whereas V. americana had 62% of its leaf biomass within 30 cm of the bottom. Vallisneria had a light extinction coefficient ranging from 0.013 to 0.019 m2·g-1, much higher than the value (ca. 0.006 m2·g-1) for M. spicatum. This indicates less effective penetration of light to lower leaves of V. americana. Half-saturation constants describing the light-dependence of carbon uptake in "shade" and "sun" tissues ranged from 60-197 microeinsteins·m-2·s-1 for V. americana, and 164-365 μeinsteins·m-2·s-1 for M. spicatum. The optimum temperature for photosynthesis was 33.6°C for M. spicatum and 32.6°C for V. americana, but Myriophyllum was nearly twice as effective at carbon uptake at 10°C. Integration of all of the above features with WEED showed that, for midsummer conditions, V. americana more than compensated for apparently disadvantageous morphological features by its greater physiological adaptability to low light regimes. Coupled with the temperature-dependence of photosynthesis, it appears that V. americana is favored by midsummer conditions, whereas M. spicatum is at an advantage at other times.

The delay in 14C fixation rates by three submerged macrophytes. A source of error in the 14C technique

The time course of the 14C fixation rate was determined for Fontinalis antipyretica L., Elodea canadensis Michx., and Littorella uniflora (L.) Aschers. An initial delay in reaching a constant 14C fixation rate was found. The time lag was shortest in plants previously treated with light and in plants lacking, or with few, lacunae. The time lag produced an error when using the 14C technique for measuring macrophyte productivity. In 1 h incubations of plants previously treated with light, the “true” fixation was underestimated by 0.2, 8 and 14% for Fontinalis, Elodea and Littorella, respectively and by about 1.0, 40 and 30% for plants kept in the dark before incubation. The effect of the lacunae and different pre-experimental conditions are discussed.

Resistance of the Microbial Community within Salt Marsh Soils to Selected Perturbations

The response of the soil microbial community in a short Spartina alterniflora salt marsh to selected, long term perturbations was examined. Alternative hypotheses of linkage between macrophyte production and the microbial community biomass and activity were tested. In 2 perturbation experiments macrophytic primary production was removed from marsh plots by clipping shoots and printing beneath ground parts for periods up 10 18 mo. In a third experiment monthly enrichments of glucose, ammonium nitrate and their combination were made for 5 mo to both clipped and pruned plots as well as unclipped control plots. The state of the microbial community was monitored by adenosine triphosphate and total adenylate concentration, community adenylate energy charge ratio and anaerobic uptake of 14C—glucose by mud slurries. The overall responses of the various parameters were consistent with the hypothesis that the soil microbial community is relatively unlinked to plant growth. This "unlinking" appears responsible for the observed resistance to change by the microbial community in the face of perturbations to the marsh system. Two mechanisms of resistance were postulated. First, while the microbial community resides in a large reservoir of organic matter, most of this organic matter may be relatively refractory. Hence, the microorganisms would be nutrient limited by the slow transformation of this material. Such a large resource pool with a long turnover time would promote resistance to perturbations that alter plant productivity. Second, the microbial community would be resistant to changes rather than nutrient status if in fact it were limited by physiochemical, spatial constraints rather than nutrients. While neither hypothesis could be totally rejected, our results give greater support to the second hypothesis.

Growth and production of aquatic macrophytes in a south temperate saline lake

(1978). Growth and production of aquatic macrophytes in a south temperate saline lake. SIL Proceedings, 1922-2010: Vol. 20, No. 2, pp. 1153-1158.

Primary Productivity of Emergent Macrophytes in a Wisconsin Freshwater Marsh Ecosystem

In 1972 primary production of various emergent macrophytes was examined in Theresa Marsh, a shallow, semimanaged impoundment in southeastern Wisconsin. Dominant macrophytes included Typha latifolia, Scirpus fluviatilis, Carex lacustris, Phalaris arundinacea and a shrub, Salix interior. Seasonal patterns of production as well as total production varied greatly among species. With estimates for litter loss and belowground production, annual net primary production ranged from 1181 g/m/sup 2//year for Carex lacustrris to nearly 3200 g/m/sup 2//year for Typha latifolia. Peak standing crop values were generally among the highest reported. Average productivities during the growing season, however, were relatively low, ranging from 6.31 to 10.52 g/m/sup 2//day for aboveground standing crops. Primary production was also estimated for transient species that occurred on mud flats following a marsh drawdown. The high primary production within the marsh appears to be based on high nutrient levels as indicated by the marsh water and soil chemistry.

A mechanism to account for macrophyte decline in progressively eutrophicated freshwaters

Artificial fertilization of lakes ultimately leads to reduction in submerged macrophyte productivity. This has usually been attributed to shading by increasing populations of phytoplankton. Evidence is given that loss of macrophytes is often due to increased growth of, and shading by, epiphytes and filamentous algae associated with the weed beds, and that phytoplankton development is subsequent rather than causative. A new hypothesis is outlined in Fig. 1 and support for it is drawn from palaeolimnological studies, laboratory experiments and field observations and experiments in the Norfolk Broads, an area of shallow, peat-excavated lakes, and from the literature.

Effects of Thermal Effluent on Standing Crop and Net Production of Elodea canadensis and Other Submerged Macrophytes in Lake Wabamun, Alberta

SUMMARY (1) The dry matter production of aquatic macrophytes was measured over 2 years, at three depths, in Lake Wabamun, Alberta, Canada. Production was measured in an area receiving thermal effluent and at a control site, unaffected by thermal effluent. (2) A greater standing crop existed in winter in the thermal mixing zone. Elodea canadensis, which had no marked dormancy mechanism, was dominant in this zone in winter. (3) Higher light levels, due to the absence of ice cover, resulted in earlier spring growth in the effluent zone, but early spring productivity was limited by low water temperatures, caused by strong thermal stratification. Elodea dominated early spring production because of the large standing crop overwinter. (4) After turnover, the growth of E. canadensis increased and vegetative and potential sexual reproduction increased compared to the control site. Elodea comprised only approximately one-third of the maximum standing crop at the control site in the first year, and was absent the second year. (5) Large standing crops of Elodea near the surface were thinned by wave action. The resulting stem fragments were spread throughout the lake, where they established during the growing season but later declined. Following this process of thinning, a second peak in the standing crop was observed. (6) Changes in the species composition of submerged macrophytes in heated areas of Lake Wabamun do not seem to have spread to unheated acres of the lake.

The distribution and production of macrophytes in Lunz Mittersee and Lunz Untersee

The distribution and production of macrophytes in Lunz Mittersee and Lunz Untersee

Production by freshwater vascular plant (Macrophyte) communities of lakes and reservoirs in the European part of the U.S.S.R.

Data on the annual net primary production by macrophyte vegetation are given for 5 lakes in northern Russia and for altogether 8 river reservoirs, 5 on the Volga and 3 on the Dnieper rivers. The monozonal (littoral) lakes Laca, Vože and Kubenskoje are by one to two orders of magnitude more productive in macrophytes (per unit lake area) than the polyzonal large lakes Ladoga and Onega. In the 5 Volga river reservoirs, the annual macrophyte production decreases downstream, from some 92 to 3.5 g C per 1 m2. In the Dnieper river reservoirs, the macrophyte production varies from 19.3 to 7.9 g C per 1 m2 per year.

Limiting factors and productivity of macrophytes

The paper summarizes the present state of knowledge on submerged and emergent macrophyte productivity as related to both natural and man-induced environmental factors. Particular attention is paid to the light and CO2 regimes, mineral nutrient supply and competitive relationships. All these factors are subject to marked changes with the present large-scale eutrophication of waters. Pronounced alterations in the structure of macrophyte vegetation over large areas represent a predictable outcome of these changes. The role of macrophytes in aquatic ecosystems, especially in temperate lakes, is also discussed.

The primary productivity of submerged macrophytes in West Blue Lake, Manitoba

The productivity of Potamogeton Richardsonii, P. pectinatus, Myriophyllum alterniflorum, Megalodonta Beckii, and Chara vulgaris in West Blue Lake, Manitoba, is reported. Measurements of changes in biomass and assimilation of 14CO2 in random and non-random samples throughout the growing season of 1973 were used. Changes in biomass of P. Richardsonii, M. alterniflorum, M. Beckii, and C. vulgaris determined from random samples compared favourably with those determined from non-random samples. This was not the case for P. pectinatus because of its restricted occurrence. Similarly, measurements of 14CO2 assimilation in random samples of P. Richardsonii, M. alterniflorum, and M. Beckii compared well with non-random samples. Productivity values derived from 14CO2 uptake were far in excess of those attained from biomass changes. Seasonal trends of production and the depth distribution of production are discussed, and macrophyte production is compared with phytoplankton production.

Nutrient Release and Community Metabolism Following Application of Herbicide to Macrophytes in Microcosms

In laboratory studies, the death of macrophytes is followed by decomposition and some release of nutrients into the water (Jewell 1971; Simsiman, Chesters & Daniel 1972; Nichols & Keeney 1973). In field studies, applications of herbicides to control macrophytes may result in an increase in the P and N content of the water (Walker 1963; Daniel 1972) or it may have little effect on the concentration of these nutrients (Fish 1966; Brooker & Edwards 1973). Herbicide applications to reservoirs may reduce both gross production and total respiration, causing no change in their ratio (Brooker & Edwards 1973), however, Strange & Schreck (1976) found an increase in 02 consumption by the aquatic community after treatment, indicating a relative increase in respiration, a decrease in production, or both. Other workers have reported reduced dissolved oxygen concentrations (DO) following herbicide treatment (Ernest 1971; Simsiman et al. 1972; Daniel 1972). A reduction in macrophyte production following herbicide application may be accompanied by an increase in the productivity of other plants such as phytoplankton (Walsh, Miller & Heitmuller 1971; Strange & Schreck 1976). Large outdoor pools (microcosms) have been successfully used in studies of aquatic communities (Goodyear, Boyd & Beyers 1972). These microcosms allow replication, control, and quantification of usually unknown variables, but at the same time provide near natural conditions.

Distribution and biomass of submerged macrophytes in Neusiedlersee

Within the area of the open, reed-free zone in Neusiedlersee there exists a clearly defined region with Myriophyllum spicatum L. and Potamogeton pectinatus L. Phytosociological estimates, quadrat counts and direct harvest methods have been combined over a 3-year period in order to estimate the extent, density and production characteristics of the zone. Quantitative studies have been concentrated on the northern part of the lake which the previous survey (Schiemer and Weisser, 1972) had indicated as the major zone of macrophyte growth. Evidence is presented for a distinctive inshore-offshore distribution of M. spicatum. The interaction of wave action and sedimentation rates of fine inorganic material is considered to be principally responsible for this pattern as well as for the overall distribution of both species. However, the distribution pattern of P. pectinatus shows a lesser degree of dependence upon such factors. Computations of the total biomass and annual production of macrophytes within the lake are presented and a comparison is attempted between the status of macrophyte production within Neusiedlersee and that estimated for other shallow lakes. The constant reduction in extent of the macrophyte belt during the observation period is discussed in relation to the artificial increase in water level and eutrophication phenomena (significantly increased phytoplankton and epiphytic algae) during recent years.

The primary productivity of marine macrophytes from a rocky intertidal community

This study represents the first report of primary production rates for Southern California intertidal producers. The production rates of 18 marine macrophytes near Wilson Cove, San Clemente Island, are close to those for other marine algal communities. No apparent relationship was revealed between the productivity of an alga and the division to which it belongs; however, productivity was associated with growth form. Encrusting prostrate forms were the lowest producers in terms of g C/m2/h and g C/g dry weight/h; sheet-like and finely-branched forms showed a greater productivity than coarsely-branched forms. Gelidium pusillum and Ulva californica had considerably greater production rates than the other algae measured.

Role of Benthic Plants in Fertilized Estuary

A study to elucidate the productivity contribution of benthic macrophytes in a fertile estuary was undertaken. Methods for utilizing C\U14\N uptake as a productivity monitor of benthic plants are described. Both phytoplankton and macrophyte productivity determinations were made at various distances from a small sewage outfall, and the effect of nutrients on the phytoplankton and seaweeds was observed. It was also observed that the benthic flora was a better indicator of nutrient enrichment, because there was a uniform gradient of productivity stimulation away from the outfall. The phytoplankton showed erratic values at various distances from the outfall due to mixing in and out of the fertilized zone. It is proposed that a productivity model such as the Baule-Mitscherlich relationship can be used to predict the photosynthetic response of algae due to a combination of nutrients. This model will allow for the concept of multiple limiting nutrients in nature.

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

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