Effects Of Salinity Changes Research Articles

Fungi of the Chesapeake Bay and Its Tributaries. III. The Distribution of Wood-Inhabiting Ascomycetes and Fungi Imperfecti of the Patuxent River

The effects of changes in salinity and temperature on the distribution of wood-inhabiting Ascomycetes and Fungi Imperfecti in the Patuxent River were studied. Forty-one species of Ascomycetes and 83 species of Fungi Imperfecti were collected; Pyrenomycetes and dematiaceous Hyphomycetes predominated. Salinity was the most important factor affecting the distribution of fungi, and the major change in species composition occurred where freshwater and saltwater mix. The ratio of Ascomycetes to Fungi Imperfecti increased with increasing salinity, while the number of species collected generally decreased. Triadelphia heterospora Shearer and Crane was collected only at low temperatures and appears to be the only regularly occurring species whose distribution was affected by temperature. The interaction of temperature and salinity did not affect the distribution of four species that occurred regularly at wide ranges of temperature and salinity. Species composition differed between two limnetic stations, one above and the other below the discharge points of two sewage treatment plants.

Ökologie der Bodenbiozönosen in der Posjet-Bucht (Japanisches Meer) und die Besonderheiten ihrer Verbreitung in Verbindung mit physikalischen und chemischen Bedingungen des Habitats

1. By employing autonomous diving techniques, direct observations on the biocoenoses of the upper marine zones were carried out. The population of each biotope was studied quantitatively in areas from 100 m2 to 1/10 or 1/100 m2 depending on size and density of the organisms studied. 2. The quality and quantity of bottom organisms depend not only on the nature of the ground, other physico-chemical environmental factors or the quantity of food available, but also on the “biocoenotic background”, i. e. conditions created by aggregations of certain species whose presence create additional, new niches. 3. In estuaries and lagoons, salinity greatly affects biocoenosis composition. The effect of salinity changes increases from phytal and epifauna to infauna elements, a fact which may be associated with the relatively higher salinity inside the bottom substratum. 4. The most highly effective force in determining distribution, composition and biogeographical structure of biocoenoses is the water temperature (absolute values as well as fluctuations). 5. In half-closed areas of bays the patchiness of biocoenoses tends to increase and the territories occupied become smaller. These changes may be associated with (a) higher fluctuations of physico-chemical conditions, (b) their increased variety and (c) accelerated succession. 6. There is the closest connection between the distribution of organisms and the position of the layers of definite water masses in the system of vertical marine zones. In the Bay of Possjet the low border of the particular vertical zone lies at a depth of 5 m (0 to 5 m); its location is determined by the position of the upper layer of the surface Japanese marine water mass. 7. When carrying out biogeographical studies, in addition to comparing similar vertical zones, one should consider bionomically similar areas.

Tolerance of the Snail Thais Floridana to Waters of Low Salinity and the Effect of Size

The snail Thais floridana is one of the prominent molluscs of the Gulf coast. It is well known to oyster fishermen there as a predator of oysters. The size of this animal is considerably smaller in the vicinity of Pensacola than it is west of the Mississippi; also, the architecture of the shells is typically different. Thais floridana floridana Conrad from Santa Rosa Sound is a smooth-shelled form, whereas Thais fioridana haysae Clench, obtained in Grand Bayou and from Sugar House Reef, Barataria Bay, La., is characterized by a double row of protruding knobs about the largest whorl of the shell. The identification of these two geographical varieties was kindly made by Dr. Paul Bartsch of the United States National Museum, from specimens sent to him. Snails from various localities were used together in these experiments in order to obtain a complete range in size. There did not seem to be any specific difference in their reaction to the experimental conditions. In view of the fact that salinity is one of the important ecological variables of confined coastal waters, such as obtain in Santa Rosa Sound and Barataria Bay, a study was undertaken of the effects of salinity changes, particularly from high to low salinity, on the snail Thais. The significance of the study is twofold. First, there is the consideration that animals living in or near the tidal zone must in one way or another exhibit a high degree of tolerance to salinity changes in order to survive. A study of behavior in relation to this environmental factor is therefore of general importance to the great animal majority which makes the littoral zone the most populated region of the sea. Secondly, inasmuch as the snail under investigation is an important enemy of oysters, and in view of the fact that grounds where both the oyster and the snail live are normally subject to dilution with river water, a study of the salinity tolerances of Thais may have practical value in determining the location of planted oyster beds. This hypothesis is based, of course, on the supposition that the oyster itself possesses a higher range of tolerance than does the snail. All information now available (communication from Dr. A. E. Hopkins) indicates that such is actually the case. The work here reported was done at the U. S. Fish and Wildlife Service Laboratory at Pensacola, Florida, during the first half of the year 1942. For the use of the laboratory and for extending opportunities for studies in the field, I am deeply indebted to the Director, Dr. A. E. Hopkins. Material was collected locally; and from Barataria Bay by courtesy of Mr. J. N. McConnell of the Department of Conservation, who kindly allowed the use of the facilities of the patrol boat Louisiana for the purpose.

The Effect of Salinity Changes on the Water Content and Respiration of Marine Invertebrates

ABSTRACT Schlieper’s theory of the function of increased oxygen intake by “homoi-osmotic” marine invertebrates in dilute sea water in maintaining their body fluids hypertonic to the surrounding water is discussbd, and objections are brought forward to the methods used in the experiments on which his conclusions were based. By periodic weighings, and measurements of respiratory rate (under narcotic) by Barcroft manometers, it was found that the weight of N. diversicolor, on transference to water of low salinity, at first increases and then falls, and that the respiratory rate is at first increased and later tends to decrease. With N. cultrifera the weight increases to a higher value and does not subsequently fall, and the respiratory rate is also increased but to a lesser extent than with N. diversicolor. These differences in the amount of increase in respiratory rate are more marked in water containing only 16·6 per cent, sea water than in water containing 25 per cent, sea water. N. diversicolor maintains its activity while N. cultifera becomes practically inert in dilute water. The latter does not actually die in 25 per cent, sea water after 100 hours, but dies in 16·6 per cent, sea water after about 50 hours. Exposure to Mjiooo KCN or to anaerobic conditions in dilute water tends to break down the mechanism by which the free osmotic inflow of water in N. diversicolor is prevented, and the weight curves under these conditions approach the N. cultrifera form. The respiratory rate of G. ulvae increases progressively with dilution of the sea water, and is roughly proportional to the initial difference of osmotic pressure inside and outside the animal. The swelling of Gunda in dilute water is due to swelling of the gut cells, which become much vacuolated. The other tissues appear unaltered. M/1000 KCN or anaerobic conditions cause a greater amount of swelling in Gunda in a given salinity than normally occurs. These experiments seem to give reasonably good support to Schlieper’s hypothesis. The mechanism responsible for this “osmotic resistance” in N. diversicolor must be of a somewhat different nature from that in G. ulvae. A rigid distinction between “homoiosmotic” and “poikilosmotic” marine animals cannot be supported.