East Coast Estuaries Research Articles

Phytoplankton and primary production in the lower Hudson River estuary

A survey of the reaches of the Hudson River between New York Harbor and Poughkeepsie showed that the spatial distribution of phytoplankton occurred in longitudinal gradients along the estuary with maximum standing crops of phytoplankton found in the Tappan Zee and Haverstraw Bay. The patterns of distribution of gross primary productivity closely corresponded to the temporal and spatial distribution of phytoplankton standing crop. Estimated daily areal gross primary production in the Hudson River estuary appeared comparable to that in other east coast estuaries and estimated annual gross primary production in most of the estuary appeared to be in the range (100–200 g C m −2 year −1) characteristic of coastal environments near New York. In the shallow waters of the Tappan Zee and Haverstraw Bay annual primary production appeared greater and likely approximates maximum production found in other river mouth estuaries.

The mechanism of iron removal in estuaries

A survey of U.S. east coast estuaries confirms that large-scale rapid removal of iron from river water is a general phenomenon during estuarine mixing. The river-borne ‘dissolved’ iron consists almost entirely of mixed iron oxide-organic matter colloids, of diameter less than 0.45 μm, stabilized by the dissolved organic matter. Precipitation occurs on mixing because the seawater cations neutralize the negatively charged iron-bearing colloids allowing flocculation. The process has been duplicated in laboratory experiments using both natural filtered and unfiltered river water and a synthetic colloidal goethite in 0.05 μm filtered water. The colloidal nature of the iron has been further confirmed by ultracentrifugation and ultrafiltration. A major consequence of the precipitation phenomena is to reduce the effective input of ‘dissolved’ iron to the ocean by about 90% of the primary river value, equivalent to a concentration of less than 1 μmol per liter of river water.

The feasibility of oyster raft culture in east coast estuaries

Styrofoam-floated oyster rafts were used to study the feasibility of raft culture in typical American east coast estuaries. Rafts were placed in Delaware Bay and several tidal tributaries in the state of Delaware. Four types of cultch were tested for resistance to the environment and utilization by setting spat. Hatchery-spawned oysters were reared on rafts and their growth and mortality were monitored. A special raft with moveable trays was designed to study the effectiveness of air drying in controlling fouling. Rafts withstood the environmental conditions in small tidal rivers but were severely damaged by waves in Delaware Bay. Although spat set was too low for commercial purposes in the rivers, sets approaching commercial density were obtained in the bay by putting bundles of strings on the oyster beds during setting. Oysters grown on rafts reached market size in approximately 2 years in two of the rivers: slower growth was noted in the other rivers. It was shown that fouling could be controlled effectively by air drying for 4 h each week. An economic analysis of raft culture for this area was conducted at the conclusion of the study, which showed that relatively high prices would be necessary to maintain a raft-based industry at this time.

Dissolved and particulate humic acids in an east coast estuary

Seasonal variations in dissolved and particulate humic acids were studied for a one year period in an east coast estuary. Particulate humic acids accounted for the bulk of the two fractions. The general seasonal trend of both factions showed a sharp increase in concentrations in the spring followed by a decrease during the summer and winter months. Concentrations of humic acids were related to salinity levels in this stratified system.

DDT residues in an east coast estuary: a case of biological concentration of a persistent insecticide.

DDT residues in the soil of an extensive salt marsh on the south shore of Long Island averaged more than 13 pounds per acre (15 kilograms per hectare); the maximum was 32 pounds per acre (36 kilograms per hectare). A systematic sampling of various organisms from the vicinity showed concentrations of DDT increasing with trophic level through more than three orders of magnitude from 0.04 part per million in plankton to 75 parts per million in a ring-billed gull. Highest concentrations occurred in scavenging and carnivorous fish and birds, although birds had 10 to 100 times more than fish. These concentrations approach those in animals dying from DDT poisoning, which suggests that many natural populations in this area are now being affected, possibly limited, by DDT residues. Similar concentrations have been reported elsewhere in North America.

Nature Lover: The Magazine of the Countryside

The recent publication of volume 4, No. 1 of Nature Lover, the magazine of the countryside, marks the revival of a much-needed popular journal which deals with the natural history and archæology of the British countryside. The greatest merit of the journal is that it chooses good, representative subject-matter which is fairly easily available, thus bringing these rural sciences within the reach of everyman. The present number contains short, readable articles on the “Unity of Nature” by C. H. Warren, “Secretive Badgers” by B. M. Nicholas, “British Fritillary Butterflies” by L. H. Newman, “Jimmy the Lizard” by Frances Pitt, “The Numbers of Animals” by Brian Vesey-Fitzgerald, “Water Problems of Fishes” by Chapman Pincher, “Some Strange Plant Habits” by Wolseley Banks, “Bird-watching on an East Coast Estuary” by R. H. Harrison, “Lavenham, Suffolk” by Geoffrey Morgan. Among these authors are some of Britain's best natural history writers, and some of the articles are illustrated by good photographs. This monthly journal can be strongly recommended to the general lay reader who is interested in country-life and natural history, and it should be encouraged in all our secondary schools, for its method of presentation is bound to stimulate interest. Subscription to Nature Lover is 16s. 6d. a year, including postage. Further information can be obtained from Nature Lover, Staples House, Cavendish Place, London, W.I.