Franklin C. Daiber

Response in production of cord grass,Spartina alterniflora, to inorganic nitrogen and phosphorus fertilizer

Fertilization of a low marsh area inhabited by the cord grass,Spartina alterniflora, with inorganic nitrogen and phosphorus compounds was conducted on a monthly basis during the 1972 growing season. Yield of the cord grass, as measured by an increase in fresh weight after its harvest, was significantly higher in the nitrogen fertilized area when compared to the phosphorus fertilized site and a control area. No effect of phosphorus could be demonstrated. It was concluded that nitrogen supplies are limiting production of dwarf formS. alterniflora in the salt marsh under study, and further suggested that introduction of additional sources of inorganic nitrogen into a marsh deficient in nitrogen would tend to increase its productivity.

Remote sensing of biomass and annual net aerial primary productivity of a salt marsh

Spectral radiance data, simulating bands, 3, 4, and 5 of the Landsat 4 thematic mapper, were collected with a hand-held radiometer in a Delaware Spartina alterniflora salt marsh. Previously developed regression models were used to estimate live and dead biomass from canopy radiance data. Spectral radiance data were expressed as vegetation or infrared index values. Biomass estimates computed from the models were in close agreement with biomass estimates determined from harvesting during most of the growing season. Both dead biomass and soil background reflectance attenuated vegetation index biomass predictions, whereas only dead biomass reflectance attenuated infrared index biomass predictions. As a result, the infrared index yielded biomass means more similar to harvest biomass means in low live biomass areas, and the vegetation index yielded mean biomass estimates more similar to harvest biomass means in high live biomass areas. Annual net aerial primary productivity (NAPP) estimates computed from spectral radiance data were generally within 10% of similar NAPP estimates computed from harvest biomass data.

Light, nitrogen, and phosphorus limitation of edaphic algae in a delaware salt marsh

The effects on edaphic algae associated with a pure stand of the cord grass, Spartina alterniflora Loisel of manipulating light intensity and additions of inorganic nitrogen and phosphorus as fertilizers to the marsh surface have been investigated for one year. The standing crop of edaphic algae as measured by chlorophyll a production was limited only by phosphorus supplies during fall and winter, by both phosphorus and nitrogen in spring, and only by nitrogen during the summer. Since the responses were in phase with the seasonal fluctuations in the concentration of nitrogen and phosphorus, it is concluded that the flood tide is the major source of nitrogen and phosphorus compounds for edaphic algal growth. Reduction in the quantity of light reaching the edaphic algae by Spartina cover is always a limiting factor for the standing crop. A gradient in the composition of the algal flora is directly related to light intensity, and indicates that this factor determines the relative contribution of diatoms and filamentous algae to the community. The interaction of light intensity and nutrients in regulating the production of edaphic algae and cord grass on the marsh under study over a yearly cycle has also been investigated.

Nitrate and nitrite in the surface waters of two delaware salt marshes

The distribution of nitrate and nitrite in two Delaware salt marshes was studied from July 1966 through December 1967. Canary Creek Marsh, located near the mouth of Delaware Bay, was characterized by high salinity, low nitrate water. The Murderkill Marsh, in central Delaware, was characterized by low salinity, high nitrate water. Man-made control structures in the Murderkill Marsh inhibited free tidal exchange and modified the distribution of nitrate and nitrite. Maximum nitrate concentrations occurred in the winter, while minimum concentrations were observed during the summer. Summer nitrate concentrations in the Canary Creek Marsh ranged from undetectable (<2 μg-at/1) to 8 μg-at/1. Winter values were generally between 10 and 25 μg-at/1. At the Murderkill Marsh winter nitrate concentrations ranged from 40 to 100 μg-at/1, and the summer concentrations were generally in the range of 5 to 20 μg-at/1. Nitrite concentrations in both areas rarely exceeded 1.5 μg-at/1, and exhibited no discernable seasonable pattern.

Remote sensing salt marsh biomass and stress detection

Abstract A hand-held radiometer was used to gather spectral radiance data simulating bands 3, 4 and 5 of the Landsat-D Thematic Mapper. Variations in biomass of the salt marsh plant Spartina alterniflora were highly correlated to changes in spectral radiance expressed as the vegetation index or the infrared index. Negative stresses like increased soil salinity and increased concentrations of copper or zinc yielded reductions in biomass which were detected spectrally. Positive stresses like freshwater and sewage effluent additions produced an increase in biomass which also were detected using spectral data. The demonstrated detection of biomass from spectral data was expanded spatially and temporally to estimate net primary productivity of a salt marsh. Remote sensing estimates of production ranged from 5 to 20% of estimates from harvest data. Future applications of this biomass estimation technique, employing data gathered from satellite platforms and from the ground, are discussed for salt marsh systems.

Diel Rhythms in Edaphic Community Metabolism in a Delaware Salt Marsh

An endogenous rhythm in edaphic salt marsh community photosynthesis was demonstrated but no evidence for a similar respiratory rhythm was found. Photosynthesis exhibited both temperature— and light—modulated rhythms. Light saturation of the system did not occur at less than 50% of full sunlight. Respiration also exhibited light— and temperature—induced rhythms. See full-text article at JSTOR

The hydrography of the Broadkill River estuary, Delaware

The hydrography of the Broadkill River, a narrow, shallow estuary in southeastern Delaware, was studied from July, 1966, through February, 1971. Measurements of current velocity, tide stage, salinity, water temperature, dissolved oxygen, pH, and turbidity were made at several stations along the course of the estuary. The Broadkill River has characteristics of both a partially-mixed and a well-mixed estuary. During normal runoff the system discharges 1.3×105 m3 of freshwater seaward per tidal cycle. The flushing time of the entire system increases from 10.3 tidal cycles during high runoff to 24.2 tidal cycles during low runoff.

Eutrophication of estuarine areas by rainwater

Total phosphorus concentrations were determined in rainwater collected at the Bayside Laboratory, Lewes, Delaware from February 1966 through January 1967. The mean concentration of winter-spring rainwater was 4.9 μg A/liter, that of summer rainwater increased to 150 μg A/liter, and fall-winter levels decreased to 8.1 μg A/liter. This phenomenon may account for atypical phosphorus cycles noted in estuarine areas.

The hydrography of the Murderkill estuary. Delaware

The hydrography of the lower Murderkill River, a small, shallow estuary in southeastern Delaware, was studied from July, 1967, through December, 1970. Variations of current velocity, tide stage, salinity, water temperature, and dissolved oxygen were measured at one station in the estuary during periods of mean and high freshwater runoff. The flushing time and mixing characteristics of the estuary during mean runoff were determined using a water-tracer dye. Seasonal and tidal variations of salinity, water temperature, dissolved oxygen, pH and turbidity were measured at seven stations along the estuary from September, 1969 through December, 1970.

FURTHER OBSERVATIONS ON THE OCCURRENCE OF HALICYCLOPS FOSTERI WILSON (COPEPODA, CYCLOPOIDA) IN THE DELAWARE BAY REGION, U.S.A.

Hadicyclops fosteri ist eine planktonische Art, die bisher nur selten in Astuarien Nordamerikas gefunden wurde. Sie erweist sich als eine der dominierenden Formen in zwei kleinen Zuflussen am sudwestlichen Ufer der Delaware Bucht. Beide Flusse sind weniger als 20 km lang und haben ein schwaches Gefalle; sie entwassern ausgedehnte Sumpfgebiete. Die Populationen von H. fosteri erreichen ihr Maximum bei Temperaturen uber 20° C und bei Salinitaten unter 2‰. Es konnten zwischen 10 000 und 750 000 Individuen pro m3 gezahlt werden. H. fosteri und Eurytemora affinis (Calanoida) sind in beiden Flussen in den Regionen mit niedrigem Salzgehalt die dominierenden Copepoden.