Showing papers by "University of Maine published in 1982"

Feeding capabilities and limitation of herbivorous molluscs: A functional group approach

Abstract: The susceptibility of an alga to an herbivorous mollusc depends, in part, upon the size and toughness of the plant relative to the feeding ability of the mollusc. In this study, algae are subdivided into seven functional groups based on these and other physiological characteristics. Herbivorous prosobranchs and chitons are subdivided into four functional groups based on the structure of their feeding apparatus. Distinct patterns in the diets of these molluscs are evident when feeding data, based on these functional groups, are examined. Most herbivorous mollusc species eat algal forms that are either minute (i.e., micro- and filamentous algae) or very large and expansive (kelp-like or crustose algae). Algae of intermediate size (erect forms 1- to 10-cm tall) are eaten to a lesser extent, possibly because they are too large to be rasped from the substratum and too small for most herbivores to occupy. Herbivorous archaeogastropods (excluding limpets) and mesogastropods tend to eat filamentous and microscopic algal forms predominantly, whereas limpets and chitons feed on large, leathery and crustose algae. These dietary differences reflect functional differences in the feeding apparatus of these herbivore groups. Radulae of herbivorous mesogastropods function like rakes and can ingest larger, tougher algae than can radulae of nonlimpet archaeogastropods. The latter function more like brooms by sweeping the substratum broadly, but exerting little force. Limpets and chitons have superior excavating abilities because their radulae have: robust buccal muscles surrounding them, a reduced number of points of contact on the substratum, and minerally hardened teeth. The feeding apparatus of chitons is most versatile since it possesses features found in all herbivorous gastropod functional groups, and thus, it can sweep and excavate simultaneously. This functional group approach suggests various hypotheses concerning algal community structure, plant/herbivore and herbivore/herbivore interactions, the relative importance of structural defenses in algae, and the evolution of specialized grazers. These hypotheses are examined using data from published accounts.

Development and validation of a physical self-efficacy scale.

Abstract: Theory development in the area of. perceived physical self-efficacy has been impeded by a lack of psychometrically sound instruments to measure physical self-concept. Six studies were conducted as part of a research program designed to remedy this deficiency by creating an individual-difference measure of physical self-efficacy with adequate psychometric properties. In the first study, data from a large pool of items that had been administered to undergraduates were factor analyzed, and two underlying dimensions within a global measure of physical self-efficacy were identified: a Perceived Physical Ability factor and a Physical Self-Presentation Confidence factor. The second study was aimed at the establishment of the stability of these two subscales and the total scale, Test-retest and alpha coefficients were found to be highly satisfactory. The remaining four studies were concerned with determining the construct validity of the scales. In line with theoretical expectations, subjects who perceived themselves as having excellent physical skills had higher self-esteem, an internal locus of control, a lack of social anxiety and self-consciousness, and a tendency to engage in adventurous physical activities as well as disinhibiting sexual experiences. It was also found that subjects with positive perceptions of their physical competence outperformed subjects with poorer self-regard in this sphere on three tasks involving the use of physical skills. Finally, potential uses for the scale in medical, physical education, and clinical settings are discussed.

A Limpet‐Coralline Alga Association: Adaptations and Defenses Between a Selective Herbivore and its Prey

Abstract: The population density of the limpet Acmaea testudinalis is highest on the crustose coralline alga Clathromorphum circumscriptum in both tide pool and subtidal environments in the Gulf of Maine. Juvenile limpets recruit to C. circumscriptum and both juveniles and adults preferentially feed on this species (not its epibionts) over a choice of other corallines, foliose algae, microalgae (diatoms), and detritus. Abundances of the predator (limpet) and the prey (coralline) are positively correlated, and the fitness of both organisms may be increased by the association. Acmaea testudinalis possesses a radula apparently adapted to eat efficiently C. circumscriptum, a food of low caloric value. The coralline is not only an abundant and dependable food throughout the geographic range of the limpet but also provides a superior holding surface for it. Clathromorphum circumscriptum requires grazing to remove potentially lethal epiphytes, but is not harmed by limpet grazing since it possesses a uniquely thick protective tissue over the region of growth. Reproductive structures of C. circumscriptum develop in winter and are buried below the surface so the effects of grazing on them are minimal. Over a wide range of depths, the rate of cell removal by limpets matches the rate of cell production by Clathromorphum. The number of apparently specific adaptations of both organisms, with mutual advantages, suggests evolution toward a coevolved interdependency. Trophic specialization of small organisms with low mobility (limpets) on larger, longer lived prey (coralline algae and kelps) is more likely than in other herbivore/prey interactions. By specializing on a long—lived and predictable food source, A. testudinalis may have evolved a strategy of economy by minimizing its cost of foraging (risk to predation and energy expenditure) relative to its absolute intake of calories. This foraging strategy may have been reinforced over time since it also improves the survivorship of the preferred prey.

Friendship Networks in Developing Relationships: Converging and Diverging Social Environments

Abstract: Changes in the structure offriendship networks are thought to complement change in a couple's level of involvement in a close relationship. As a pair become close, their network of mutual friends should increase in size, and with declining involvement a concurrent reduction in the number of mutualfriends should occur. A measure of network overlap was derived from daily reports of social activity provided by participants. The hypothesized variations of stage and overlap are consistently supported in both cross-sectional and longitudinal tests. Network overlap covaries with stage of relationship, and this covariation cannot be accounted for by a couple's familiarity or length of dating. Underlying variations in overlap are compositional changes in the stability of the network membership, involving either the reclassification of friends or actual changes in network membership. The findings are discussed in terms of the importance of considering the social context of developing relationships, since that context can serve both facilitative and disruptive functions.

Oxygen production by endosymbiotic algae controls superoxide dismutase activity in their animal host

Abstract: Aerobic and aerotolerant organisms have evolved defenses against the toxic effects of molecular oxygen1. One protective mechanism involves the breakdown of the harmful superoxide radical by the enzyme superoxide dismutase (SOD). However, levels of oxygen elevated only slightly above normal atmospheric (P O2 of 159 mm Hg) may overpower a cell's defense systems2–4. Although most animals do not naturally encounter oxygen pressures above 1 atm, hyperbaric oxygen levels normally occur in the tissues of marine animals that harbour intracellular algal symbionts, which in light generate more oxygen than is consumed by the combined host and symbionts5–10. We have now found that sea anemones Anthopleura elegantissima (Brandt) containing zooxanthellae (the symbiotic dinoflagellate Symbiodinium microadriaticum) in their gastrodermal tissues have SOD activities nearly two orders of magnitude greater than individuals totally lacking zooxanthellae.

Seasonal carcass composition and energy balance of female black ducks in Maine

Abstract: Female Black Ducks (Anas rubripes) collected in Maine during the summer, fall, and winter of 1974-1976 showed significant seasonal variation in body weight, nonfat dry weight, gizzard and pectoral muscle weight, and fat, moisture, and protein content Variation of body weight within and among seasons was correlated more strongly with carcass protein content, and with fat content during seasons of heavy lipid deposition, than with three structural size variables (culmen, tarsus, and sternum) Regression equations including fat and protein as independent variables accounted for 80-90% of the annual and seasonal variation in body weight; structural size variables alone accounted for less than 30% Immature females averaged 54 and 99 g lighter, and carried 54 and 59 g less fat than adults during the fall and winter Ducks of both age classes lost weight in December and January Adult and immature females metabolized 59 and 64 g of fat and 17 and 25 g of protein in winter compared with 46 g of fat during the nesting season Nutrient reserves are thus equally as important for the winter survival of these birds as for successfurl eproduction Seasonalc hangesi n carcass composition suggest that (1) fat deposited in late fall provides an energy reserve during winter, (2) a reduction in lean weight during winter may lower daily energy requirements and increase the effective amount of energy reserves, and (3) declining body weights during late winter may be an endogenous rhythm that reflects a shift in the expected benefits of an energy reserve compared to the costs of carrying additional weight

Metabolic responses of striped bass (Morone saxatilis) to temperature acclimation. II. Alterations in metabolic carbon sources and distributions of fiber types in locomotory muscle

Abstract: The effects of temperature acclimation on (1) fiber-type distribution, and (2) alternate metabolic fuels for energy supply within different skeletal muscle fiber types in striped bass (Morone saxatilis) were examined Histochemical analysis demonstrated an increase in the proportional cross sectional area of oxidative red fibers from 903% to 1503% during cold acclimation (25°-5°C) The rate of oxygen consumption was 178 times greater in red muscle than white in 25°C acclimated fish This ratio increased to 232 in 5° fish Oxidation of both 14C-U-glucose and 14C-1-palmitate was significantly greater in red muscle than in white at both acclimation temperatures A lack of thermal compensation for metabolism of 14C-U-glucose was exhibited by both fiber types Red muscle showed a dramatic increase in rate of 14C-1-palmitate oxidation after cold acclimation Activities of glycolytic enzymes confirmed a high glycolytic capacity in white muscle; glycolytic capacities were dependent on acclimation temperature in both fiber types Only red muscle showed a positive compensation for activities of key enzymes from aerobic metabolism The results indicate an increasing reliance on aerobic metabolism of fat in the swimming musculature at cold acclimation temperatures The capacity for sustained swimming under these conditions is conserved by (1) an increase in the relative proportion of red fibers, and (2) an enhanced capacity for energy supply in the red muscle by oxidative metabolism of stored lipid

The cichlid fish of cuatro ciénegas, mexico: direct evidence of conspecificity among distinct trophic morphs.

Abstract: The idea that different individuals within a biological species may have radically different morphologies and distinct feeding modes has commanded attention because of its profound implications for evolutionary biology. If individuals from a panmictic population are recognized as species by standard taxonomic criteria, organismal diversity in nature may be more apparent than real. This concern is particularly germane to the great diversity seen within assemblages of tropical freshwater fishes such as cyprinids and cichlids, where endemic specializations are extreme (Myers, 1960; Greenwood, 1974; Reid, 1980). Several examples of substantial dichotomous morphological divergence have been reported among sympatric collections of closely related fishes (Roberts, 1974; Sage and Selander, 1975; Vrijenhoek, 1978; Turner and Grosse, 1980). The cichlids of Cuatro Cienegas, Mexico are particularly interesting and their study by Sage and Selander set a precedent which has had a significnat impact on subsequent systematic studies (Kirkpatrick and Selander, 1979; Graves and Rosenblatt, 1980). By any phenetic criteria, the extreme distinctiveness of sympatric cichlids in Cuatro Cienegas suggests the presence of two discrete species. A "small tooth" form with papilliform pharyngeal dentition feeds on plant material and possesses a relatively narrow head, slender pharyngeal jaw, and long intestine. A "large tooth" form with molariform pharyngeal teeth feeds on snails and has a wider head, relatively stouter jaw, and short intestine. The morphological and trophic differentiation between these two forms exceeds that observed among many closely related biological species and precisely mimics the differences which define numerous cichlids in the African Great Lakes (Fryer and Iles, 1972). Further, it is this type of variation that might be associated with incipient macroevolution (Greenwood, 1979). The magnitude of differences between these forms has thus historically caused them to be treated as two distinct species (Taylor and Minckley, 1966; Minckley, 1969; LaBounty, 1974; Kornfield and Koehn, 1975). Alternatively, on the basis of the segregation of both types within wild-caught broods, complete electrophoretic similarity, and concordant patterns of allozymic variation between forms, Sage and Selander (1975) suggested that both forms belong to a single polymorphic species. However, this evidence did not provide a definitive test of the two species hypothesis (Hutchinson, 1978). We present in this article the results of complementary studies of genetics and reproductive biology initiated to resolve the biological status of these fishes. Our allozyme data and observations of mating in natural populations verify the insight of Sage and Selander and attest to their accurate electrophoretic evaluation of conspecificity. This demonstration of substantial morphological variation within a single species has significant implications for ecology and conventional taxonomic characterization.

The Size and Scattering Coefficient of Urban Aerosol Particles at Washington, DC as a Function of Relative Humidity

Abstract: The relative humidity dependence of the size and scattering coefficient of atmospheric aerosol particles was measured at Washington, DC during the period 26–31 July 1979. Particle growth curves (i.e., curves of the ratio r/r0, of particle radius to particle dry radius, versus relative humidity) were calculated using measured values of the particle composition parameter B ≡ ν¯ϕϵMwρ0/ρwMs, where ρ0 is the density of the particle in dry state, ρw and Mw the density and molecular weight of water, ϵ the mass fraction of soluble material in the particle. Ms the molecular weight of the soluble material, ν¯ the mean number of moles of ions per mole of solute, and ϕ¯ the mean value of the practical osmotic coefficient. To determine B, a mobility analyzer was used to transmit dry particles of nearly uniform size to a thermal gradient diffusion cloud chamber where the supersaturation (Sc,) necessary to activate the particles was measured. Then, a relationship between Sc, r0 and B was employed to determine...

Assessment of intertidal growth and capacity adaptations in suspension-feeding bivalves

Abstract: Curves relating instantaneous growth rate to aerial exposure were determined for six species of bivalves in laboratory and shore experiments. A dimensionless index equatable with the relative intertidal growth performance of a species was calculated by integration of the growth curve after converting both growth rate and aerial exposure to decimal fractions. Intertidal growth performance of the bivalves tested corresponded well with their natural levels of occurrence on the shore, and improved in the following order: Modiolus modiolus < Argopecten irradians < Ostrea edulis < Mytilus edulis < Crassostrea virginica. Geukensia demissa, for which an index value could not be determined, grew faster intertidally than subtidally. The relative contributions made to intertidal growth performance by energy-conserving and energy-supplementing capacity adaptations were assessed by resolving the growth curves into energy-input and energy-loss components. The rate of energy loss due to intertidal exposure was lower in the high-shore species, and also less affected by harsher subaerial conditions, than in the low-shore species. Moreover, M. edulis and C. virginica showed abilities to supplement energy input such that growth per unit immersion time was better at certain intertidal levels than subtidally. Energy conservation and supplementation in these forms made roughly equal contributions to their improved intertidal growth relative to species occurring lower on the shore.

Determination of α– and β–Carotene in Fruit and Vegetables by High Performance Liquid Chromatography

Abstract: A simple, reproducible isocratic high performance liquid chromatographic procedure has been developed to separate α–and ββ–carotene in lowbush blueberries, carrots, potatoes and fiddlehead greens. Analyses were performed using a Partisil 5 ODS column maintained at ambient temperature with a mobile phase of 85:12.5:2.5 acetonitrile-tetrahydro-furan-water. Detection was at 470 nm and 0.04 absorbance units full scale. Total analysis time, including extraction, was 30–40 min. Saponification was not required for cleanup or recovery even with samples containing large amounts of other pigments, such as blueberries and fiddlehead greens. The quantity of a-carotene varied from 1 μg/100 g wet weight of blueberries and potatoes to 8,800 μg/100 g wet weight of carrots, while β-carotene ranged from 6 μ g/100 g wet weight of potatoes to 28,100 μ g/100 g wet weight of carrots. A comparison made between this method and the AOAC procedure did not demonstrate close agreement between values obtained by the two methods.

Surface microlayer phenolic enrichments indicate sea surface slicks

Abstract: The realization by early investigators that oil films spread on surfaces of bodies of water could mimic slick conditions1–3 has evolved into the present model of slicks resulting from monomolecular films that modify wave characteristics and hence reflectance properties of surfaces. However, the lipid materials postulated to form monomolecular layers constitute only a small fraction of the organic material in either bulk sea water or at the surface4–7, may not retain their strong surface activity in the presence of natural seawater dissolved organic material (DOM)8, and have not been found in any consistent relationship with slicks7,9–11. The apparent association of slicks with macroalgae has also been noted12–15, but there has not been a demonstration of macroalgae-derived DOM in slicks. I show here that enrichments of UV-absorbing phenolic materials, consistent components of surface microlayers16, offer reliable indication of slick conditions. I then suggest that: (1) slicks result not from monomolecular films, but from viscosity changes in surface microlayers caused by more soluble organic components; and (2) the occurrence of slicks therefore depends not on absolute concentrations of surface-active materials, but on relative viscosity differences. Evidence is also given demonstrating the presence of macroalgae-derived phenolic materials in slicks.

A behavioral study of middle-aged chest pain patients: Physical symptom reporting, anxiety, and depression

Abstract: Three groups of patients (32 to 72 years of age), admitted for cinearteriography, were tested approximately 24 hours before the procedure. Measures of symptom self-reporting, anxiety, depression, and neuroticism were employed. The major group of interest had no prior history of myocardial infarction and other forms of heart disease, but was scheduled for cinearteriography because of anginal pain and other indications of angina pectoris. Based on the results of arteriographic studies (available after behavioral testing was complete) this group was divided into two major groups of interest: one with clinically significant coronary artery disease and one with angina pectoris syndrome but no clinically significant coronary artery disease. A third group had experienced one or more infarctions and had been diagnosed as cardiovascularly diseased prior to behavioral testing. Anxiety, depression, and symptoms reported were significantly higher for the subjects who experienced angina-like pain but were fou...

The Relationships of Observer Characteristics to Beliefs in the Causal Responsibility of Victims of Sexual Assault

Abstract: Whereas much of the previous research has focused on the influence of victim characteristics on attributions of responsibility to a rape victim, the present study sought to assess the relative effectiveness of individual differences among observers in predicting perceptions of a rape victim's responsibility in her own victimization. Specifically, observers' sex, their attitudes toward women, and their degree of dogmatism significantly contributed to the prediction of victim responsibility in a multiple regression analysis. Observers' locus of control orientation, personal-environmental attributional tendency, and belief in a just world, however, failed to be of predictive utility.

Modern and Paleolimnological Evidence for Accelerated Leaching and Metal Accumulation in Soils in New England, Caused by Atmospheric Deposition

Abstract: Empirical field evidence for changing chemical processes in soils caused by atmospheric deposition of pollutants consists of: (1) Long-term water quality data including total dissolved solids, concentrations of specific metals (e.g. Ca), and conductivity; (2) Cation exchange capacity and base saturation values for soils located on precipitation pH gradients; (3) Lysimeter studies; and (4) Chemical analysis of organic soils on precipitation pH and metal gradients. For well-drained organic soils, as precipitation pH decreases, metals are differentially leached at an accelerated rate (Mn > Ca > Mg ≥ Zn > Cd and Na > Al). Experimental field and laboratory lysimeter studies on soil columns yield similar results, with increases in leaching rates for soil solutions with pH = 3 up to 100 × values for soil solutions with pH = 5. Nearly 100% of the Pb from precipitation is accumulating in the organic soil layer or sediments. Zn is accumulating in soils and sediments where the pH’s of precipitation, soil solutions, and surface waters are generally above 5 to 5.5. At lower pH values Zn and other chemically similar elements are desorbed/leached (net) at an accelerated rate.