Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Primary Production in the Patuxent River

Raymond G. Stross and John R. Stottlemyer
Chesapeake Science
Vol. 6, No. 3 (Sep., 1965), pp. 125-140
Stable URL: http://www.jstor.org/stable/1350844
Page Count: 16
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Primary Production in the Patuxent River
Preview not available

Abstract

Rates of production were measured at 22 stations located in a 29-mile segment of the Patuxent River Estuary. The river was sampled in mid-stream at 12 stations which were distributed from a point near Solomons, Maryland, to Milltown Landing upstream. Thirteen of the stations were arranged in three transects, which spanned the river in the vicinity of Chalk Point. Standing crops of chlorophyll and rates of photosynthesis were measured at a depth of 1.0 meter on 14 cruises spaced over a 23-month interval. Concentrations of chlorophyll, and co-efficients of carbon assimilation and light extinction were employed to convert estimates at a depth of 1.0 meter to rates of production for the entire water column. Both salinity and thickness of the euphotic layer showed a considerable gradient in the study area. Salinity increased threefold and thickness of the euphotic zone increased fivefold at the downstream end. The gradient was steepest in the study area upstream of the bridge at Benedict, Maryland. Concentrations of chlorophyll were related to season and position in the estuary. They ranged from 33.3 mg/ m3 in October to 3.7 mg/ m3 in December, the amplitude being largest at the upstream end of the study area. Average concentration at Station 1 was only 1/3 of the concentration 20 miles upstream at Station 22. The gradient was steeper upstream from the bridge at Benedict. Chlorophyll was least uniformly distributed in the water column immediately downstream from the bridge. Photosynthetic activity of chlorophyll, at probably subsaturation light intensity, ranged from a mean of 5.21 in August to 1.09 in December. The average for all cruises, when corrected to saturation intensities of light, was near a widely accepted value for rates of carbon assimilation per unit of chlorophyll. Rates of carbon assimilation ranged from 2.3 to 148.5 mgC/ m3/ hr. The months from June through October were the most productive in 1963. However, the Spring of 1964 was considerably more productive than was the preceding year, suggesting that the productive period is of longer duration in some years. Seasonal trends in productivity were similar at all stations along a 29-mile segment of the river. The downstream end was only 1/3 as productive on a per-unit-volume basis. Despite the larger rates of production at the upstream end of the study area, the region was least productive per unit of area, owing to the shallowness of the euphotic zone. Mean daily rates for the year were 1.2 gC/ m2 for the upstream area and 1.8 gC/ m2 for the area downstream from the bridge. The limitations of the computations for the highly turbulent upstream area are discussed.

Page Thumbnails

  • Thumbnail: Page 
125
    125
  • Thumbnail: Page 
126
    126
  • Thumbnail: Page 
127
    127
  • Thumbnail: Page 
128
    128
  • Thumbnail: Page 
129
    129
  • Thumbnail: Page 
130
    130
  • Thumbnail: Page 
131
    131
  • Thumbnail: Page 
132
    132
  • Thumbnail: Page 
133
    133
  • Thumbnail: Page 
134
    134
  • Thumbnail: Page 
135
    135
  • Thumbnail: Page 
136
    136
  • Thumbnail: Page 
137
    137
  • Thumbnail: Page 
138
    138
  • Thumbnail: Page 
139
    139
  • Thumbnail: Page 
140
    140