Alfred C. Redfield

Development of a New England Salt Marsh

The salt marsh at Barnstable, Massachusetts, occupies an embayment into which it has spread during the past 4,000 years. It exhibits all stages of development from the seeding of bare sand flats through the development of intertidal marsh to the formation of mature high marsh underlain by peat deposits more than 20 ft deep. Observations and measurements of the stages of its formation are presented. The geomorphology of the marsh is considered in relation to the factors which have influenced its development, i.e., the ability of halophytes to grow at limited tide levels, the tidal regime, the processes of sedimentation, and the contemporary rise in sea level. The rates at which the early stage of development takes place have been determined by observations during a period of 12 years and the time sequence of later stages by radiocarbon analyses.

Ontogeny of a Salt Marsh Estuary

The development of a typical New England salt marsh, and the growth of the sand spit which shelters it, during the past 4000 years has been reconstructed from soundings and borings of the peat. The results have been interpreted with the aid of observations on the structure of the marsh and estimates of the rate of its vertical accretion based on carbon-14 determinations.

Postglacial change in sea level in the Western north atlantic ocean.

Radioactive carbon determinations of the age of peat indicate that at Bermuda, southern Florida, North Carolina, and Louisiana the relative sea level has risen at approximately the same rate, 2.5 x 10-3 foot per year (0.76 x 10-3 meter per year), during the past 4000 years. It is proposed tentatively that this is the rate of eustatic change in sea level. The rise in sea level along the northeastern coast of the United States has been at a rate much greater than this, indicating local subsidence of the land. Between Cape Cod and northern Virginia, coastal subsidence of 13 feet appears to have occurred between 4000 and 2000 years ago and has continued at a rate of about 1 x 10-3 foot per year since then. On the northeastern coast of Massachusetts, subsidence of 6 feet occurred between 4000 and 3000 years ago; since then sea level has risen at about the eustatic rate. Between 12,000 and 4000 years ago, sea level rose at an average of about 11 x 10-3 foot per year. The part played by local subsidence or temporary departures from the average rate during this period is uncertain.

THE CYCLE OF ORGANIC PHOSPHORUS IN THE GULF OF MAINE

1. Methods are described for the determination of the phosphorus present in particulate form and of the total phosphorus in a sample of sea water.2. The distribution of phosphorus present as inorganic phosphate, as dissolved organic compounds, and as particulate matter (detritus and microorganisms) has been determined at all depths throughout the year at a station in the western part of the Gulf of Maine.3. In late winter over 90 percent of the phosphorus is in inorganic form and three-quarters of the remainder is present as soluble organic compounds.4. In the spring—February to May, inorganic phosphorus is converted to organic form by photosynthesis in the upper layer of water. Most of this fraction sinks to considerable depths before undergoing decomposition.5. During the summer—May to November, large quantities of dissolved organic phosphorus appear at all depths, indicating a very considerable transport of inorganic phosphate from deep water to the surface and the sinking of an equivalent amount of ph...

The Evolution of the Respiratory Function of the Blood

A CCORDING to current doctrines the mammals are the product of an evolutionary development which is traced back through the lower classes of vertebrates and is usually considered to have had its origin among the invertebrate phyla. In recent years the respiratory function of mammalian blood has been studied in great detail. Considered as a physico-chemical system concerned with the transport of oxygen and carbon dioxide, its characteristics are now well known and in many ways satisfactorily understood (35). Recent publications make it possible to compare these properties of the blood in at least one or more representatives of the various classes of lower vertebrates and of certain invertebrates. One can consequently inquire what changes in the characteristics of the blood parallel the supposed evolutionary development. In considering the evolution of the vertebrates certain general tendencies are apparent which have an obvious relation to the respiratory function of the blood. In the first place, the change from an aquatic to a terrestrial habit of life involves a profound alteration in the method of aerating the blood and in the conditions to which the blood is exposed in the respiratory organs. In the second place, the general tendency throughout the development has led to organisms increasingly capable of intense activity. This has required the development of more effective arrangements for the circulation of the blood and the transport of gases by it in order to care for greater metabolic requirements. One of the factors which has favored the greater activity of which the birds and mammals are capable is the development of a constant, high body temperature which has at the same time fixed rather definitely one of the conditions under which the respiratory function of the blood takes place. The transport of oxygen by vertebrate blood is due practically entirely to the hemoglobin present in it. Consequently the conditions under which oxygen is carried depend upon the specific properties of this substance. The transport of carbon dioxide, on the other hand, while depending in large part on reactions in which hemoglobin is involved, is a less specific phenomenon, since other proteins such as serum albumen and globulin and certain inorganic substances play a considerable role. The transport of carbon dioxide is consequently dependent in its details upon the general processes whereby the kidney and other organs regulate the composition of the blood. The hemoglobins are substances which may be decomposed into hematin and a protein, globin. The former compound contains iron in complex combination with protoporphyrin. It is to the hematin fraction that the transport of oxygen by hemoglobin is due, oxygen being combined with hemoglobin in strict

THE RESPIRATORY FUNCTION OF THE BLOOD OF URECHIS CAUPO

1. The blood of Urechis caupo contains hemoglobin enclosed in corpuscles. The oxygen capacity of the blood varies from 2.66 to 7.22 volumes per cent and the percentage of cells in the blood from 18 to 40.2. The oxygen dissociation curve is measured. Its position does not appear to be influenced by the carbon dioxide pressure. The effect of temperature upon the oxygen dissociation curve is of the direction and order observed in other bloods containing hemoglobins.3. The carbon dioxide dissociation curve is measured. The ability of the blood to combine with carbon dioxide does not appear to be influenced by the degree of oxygenation of the blood.4. The buffer value of the blood is 11 volumes per cent and is constant over a considerable range of carbon dioxide pressures. The concentration of hemoglobin accounts for the entire buffer effect.5. Carbon dioxide is about equally distributed (in concentration) between the corpuscles and plasma. The plasma contains at most a negligible quantity of buffer material. ...

THE HISTORY OF A POPULATION OF LIMACINA RETROVERSA DURING ITS DRIFT ACROSS THE GULF OF MAINE

A population of small specimens of the pteropod, Limacina retroversa, appeared in the eastern part of the Gulf of Maine in December, 1933. From collections made during the following 9 months information was obtained showing that the population was a homogeneous one, that its members grew to maximum size in 5 months, declining in numbers as they did so.A second population of small individuals appeared in the Gulf in late spring, originating chiefly from offshore, but possibly in part being offspring of the original population. These were unsuccessful in maintaining their numbers throughout the summer.In addition to the information on the life history of Limacina, the data indicate the rate of drift of the water in its circuit of the Gulf. It supplies also suggestive information on the dispersal of organisms through the lateral mixing of water. It emphasizes the dependence of pelagic organisms upon the current systems of the ocean and the difficulty involved in maintaining a permanent population in any one ...

Water Levels Accompanying Atlantic Coast Hurricanes

The water levels that occurred along the Atlantic coast during five recent hurricanes are described and compared. The forerunner, a rise in water level which may precede the passage of the storm by many hours, is found to depend upon the force and direction of the general wind field into which the storm advances. The surge that accompanies the violence of the storm depends in duration on the speed of progression of the storm center. Maximum water levels of 8 to 9 ft above the predicted tide developed at positions between 40 and 100 n mi to the right of the storm center; elevations in excess of 5 ft occurred from 50 n mi to the left to 150 n mi to the right of the center.

THE ABSORPTION SPECTRA OF SOME BLOODS AND SOLUTIONS CONTAINING HEMOCYANIN

1. The absorption of light by the blood and by purified preparations of the hemocyanin of the conch, Busycon canaliculatum, the horse-shoe crab, Limulus polyphemus, the squid, Loligo pealei, and the lobster, Homarus americanus, has been studied. It is shown that the absorption of light by solutions containing oxygenated hemocyanin may be resolved into two components: (a) that due to the true absorption by the chromatic group formed by the union of oxygen with the portion of the molecule containing copper and (b) that due to the scattering of light by the dissolved protein.2. In the analysis of the spectrum of the blood of the lobster, the absorption of light by the pigment tetronerythrin has been taken into account.3. The spectrum of the chromatic group of a given species varies very little, if at all, as the result of alterations in the hydrogen ion concentration and salt content of the solution.4. The spectra of the chromatic groups of the different species display a considerable similarity, indicating ...

FACTORS DETERMINING THE DISTRIBUTION OF POPULATIONS OF CHAETOGNATHS IN THE GULF OF MAINE

1. Data are presented concerning the distribution and numerical abundance of five species of chaetognaths taken in the Gulf of Maine during the year 1933-34 and the hydrographic features controlling their abundance is discussed.2. It is concluded that Eukrohnia hamata, Sagitta maxima and S. lyra, which are carried into the Gulf by deep currents and do not breed there, occur in numbers which depend not only on their relative abundance in various offshore waters which mingle in the Gulf, but on their longevity after entering the Gulf.3. Sagitta serratodentata is a terminal immigrant from the superficial waters of the Atlantic which fluctuates in its abundance as the result of periodic changes in the circulation of water entering the Gulf from the east.4. Sagitta elegans is the only chaetognath truly endemic to the region. The permanence of its occurrence appears to depend on the presence of a relatively stable eddy on Georges Bank. Its occurrence in other regions varies with the season to a degree which may...