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 cr...
Relationships between ash-free dry weight. viable chlorophyll a and pheopigments a were examined by linear regression analysis for non-gemmulating and gemmulated Spongilla lacustris and for an unidentified. non-gemmulating species . The primary productivity of S . lacustris was determined by both oxygen and 14C techniques and expressed on a biomass. chlorophyll a. and area basis. and the photosynthetic efficiency was calculated . The proportion of algal photosynthate excreted by the sponge was investigated. and the transfcr of algal photosynthate to the sponge was examined by antoradiography .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.