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1.
A morphometric analysis of two closely related species Astarte omaliiand Astarte basterotiwas made. Specimens were sampled from three successive stratigraphic levels of the Pliocene deposits of northern Belgium. Two chronological subspecies were distinguished—Astarte omalii omaliiand Astarte omalii basteroti. 相似文献
2.
James C. Brower 《Mathematical Geosciences》1995,27(3):399-420
The relationships between ontogeny and phylogeny have been studied for the bivalve Astarte omaliifrom the Lower, Middle, and Upper Pliocene of Belgium using canonical variates analysis, principal components in the form of multivariate allometry, and bivariate power functions or allometric equations. The results indicate that the three samples represent segments of a single evolutionary lineage which is characterized mainly by paedomorphosis where adult descendants are similar to juvenile ancestors. Recapitulation or peramorphosis is only observed for a single parameter. The Lower and Middle Pliocene samples are considered as Astarte omalii omalii,whereas the Upper Pliocene specimens are placed in A. omalii basteroti.The evolutionary trends most likely reflect changes in the living positions of the bivalves. 相似文献
3.
James C. Brower 《Mathematical Geology》1995,27(3):399-420
The relationships between ontogeny and phylogeny have been studied for the bivalve Astarte omaliifrom the Lower, Middle, and Upper Pliocene of Belgium using canonical variates analysis, principal components in the form of multivariate allometry, and bivariate power functions or allometric equations. The results indicate that the three samples represent segments of a single evolutionary lineage which is characterized mainly by paedomorphosis where adult descendants are similar to juvenile ancestors. Recapitulation or peramorphosis is only observed for a single parameter. The Lower and Middle Pliocene samples are considered as Astarte omalii omalii,whereas the Upper Pliocene specimens are placed in A. omalii basteroti.The evolutionary trends most likely reflect changes in the living positions of the bivalves. 相似文献
4.
The first data on ecology and trace metal (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb) bioaccumulation by macrozoobenthic organisms in area along the 130°E meridional transect from shallow water near the Lena River’s delta till the 78°N are presented. At the newly discovered methane seeps in the shallow Laptev Sea areas (72 m depth), a higher total abundance and biomass compared with background stations were recorded. In carbonate shells and soft tissues of Bivalvia Portlandia arctica and Astarte borealis, the high concentrations of Mn, Fe, Pb, Ni and Co were detected that varied in dependence from sampling site. In the dominating taxa of brittle stars (Ophiuroidea), there were found no significant differences between majority of trace metal content in organisms inhabiting the seeps area and background ones. An elevated content of some metals was detected in the Asteroidea bodies that may be attributed to its trophic behavior (deposit feeder). 相似文献
5.
Spatial and temporal variations in the abundances and distributions of oligochaetes of a southwestern Louisiana estuary were examined as part of a long term study of community structure of benthic macroinvertebrates. Quantitative samples were collected at monthly intervals from nine stations for two years and an additional 17 stations were sampled once. A tubificid oligochaete,Tubificoides denouxi n. sp., is described from the five species collected. The two predominant oligochaetes,Tubificoides heterochaetus andT. denouxi, were congeneric and exhibited completely allopatric distributions. Two oligochaete species with-restricted distributions,Monopylephorus helobius andLimnodriloides sp., were sympatric withT. denouxi, whileThalassodrilides belli, although less abundant, was sympatric with bothT. denouxi andT. heterochaetus. Sexually mature specimens ofT. denouxi andT. belli were collected only in the summer,T. heterochaetus was sexually mature in both winter and summer collections, andMonopylephorus helobius was sexually mature in spring and summer collections. Many of the studies of Oligochaeta have concluded that correlation exists between sediment grain size and species demography. Our data demonstrate a strong relationship between salinity and the abundance and distribution of estuarine species.Tubificoides denouxi was found only within the salinity range of 14.8 to 22.0‰ salinity,T. heterochaetus was found only within the range of 2.3 to 14.1‰, andT. belli had a salinity distribution intermediate between the previous species. No relationship was found between sediment grain-size analysis, water depth or hydrographic variables and species distribution. 相似文献
6.
Habitat-related densities of natant macrofauna were compared between vegetated and nonvegetated areas in aSpartina alterniflora marsh on Galveston Island, Texas. The most abundant macrofauna were crustaceans,Palaemonetes pugio, Penaeus aztecus, Penaeus setiferus, andCallinectes sapidus, and small fish,Gobiosoma bosci, Lagodon rhomboides, Leiostomus xanthurus, Fundulus similis andMicropogonias undulatus. Excluding residentsP. pugio, G. bosci andF. similis, most of the macrofauna were transient juveniles of estuarine-dependent species. Among crustaceans,P. pugio, P. aztecus, andC. sapidus were significantly more dense in vegetated habitat, butP. setiferus was not consistently more abundant in either vegetated or nonvegetated habitat. Of 29 species of fishes, 14 were usually in vegetation, 11 were more often on nonvegetated bottom, and 5 were indifferent to either habitat. Much seasonal variability in abundances ofP. aztecus, P. setiferus, andC. sapidus, but notP. pugio, could be attributed to changes in temperature, salinity and water-level. Strong selection for vegetated habitat byP. aztecus was related to the historical water-level pattern coinciding with seasonal periods of marsh flooding. Apparently, high seasonal tides during the spring and fall facilitated access to vegetated habitat in the marsh and exploitation by transientP. aztecus. In contrast, strong selection for vegetation byP. pugio, abundant year-around in the marsh, was not similarly influenced by seasonal changes in water-level. Overall, habitat-related densities and physical interactions suggest that marsh physiography together with differences in tides may greatly determine the extent to which certain estuarine macrofauna utilize marsh habitats. 相似文献
7.
Larvae of 15 species or genera of crabs were collected and identified during a six month (May 26 to October 28, 1978) study in the mouth of Delaware Bay. Seasonal abundance and vertical distribution of each species were investigated. Most species studied had peak abundance in July and August except forCancer irroratus andOvalipes ocellatus which showed peak occurrence in May and June, respectively. Larvae of species strongly dependent on estuarine habitats, such asUca spp.,Pinnixa chaetopterana, andP. sayana, showed a tendency to congregate in near-bottom waters where net flow of water is landward, thus favoring retention within the estuary. Larvae ofOvalipes ocellatus, Cancer irroratus, andCallinectes sapidus were more common at the surface. This vertical distribution suggests that these larvae are flushed out of the estuary. The mechanisms of recruitment and replenishment of adult populations within the estuary would therefore depend on migration of megalopa and juveniles. *** DIRECT SUPPORT *** A01BY019 00006 相似文献
8.
The waters of Naples Bay, Florida, and associated waterways were monitored for potentially pathogenic bacteria, specificallyVibrio cholerae, V. parahaemolyticus, Salmonella, andPseudomonas aeruginosa. Ten to twelve stations were sampled over a period of eleven months.Vibrio cholerae was recovered in 33.6% of the 116 total samples andSalmonella in 28.4% of the samples. The results show that these bacteria exist in these waters and can be recovered from areas with both high and low numbers of total and fecal coliforms. 相似文献
9.
Variation in morphological characters used to distinguish the three sympatric species ofPalaemonetes, i.e.,P. pugio, P. intermedius, andP. vulgaris, is suggestive of natural hybridization. Interspecific crosses among the species and intraspecific crosses of allopatric populations ofP. pugio were made to determine whether hybridization was feasible and to evaluate taxonomic characters of the juveniles. No interspecific matings produced larvae in the laboratory. Larvae, from intraspecific matings ofP. pugio andP. vulgaris were reared to 40 days of age. Larval survival rates, development time, and postlarval length ofP. pugio andP. vulgaris were not different, but juveniles ofP. pugio at 40 days after hatching were larger than those ofP. vulgaris. At 40 daysP. pugio had developed adult diagnostic features. However,P. vulgaris displayed sufficient variation in adult diagnostic features to resembleP. pugio in some cases. The intraspecific matings ofP. pugio from widely separated populations were fertile, but there was some indication of reduced reproductive compatibility in crosses involving Virginia females and Florida males relative to intrapopulational controls. *** DIRECT SUPPORT *** A01BY019 00002 相似文献
10.
Charles K. Biernbaum 《Estuaries and Coasts》1981,4(2):85-96
Between September 1976 and August 1978, samples of four species of sponge,Microciona prolifera (Ellis and Solander),Haliclona loosanoffi Hartman,Lissodendoryx isodictyalis (Carter) andHalichondria bowerbanki Burton, were collected from subtidal shell debris in a North Edisto River, South Carolina saltmarsh creek and associated amphipods identified. Dominant spongicolous amphipods wereColomastix halichondriae Bousfield,Leucothoe spinicarpa (Abildgaard),Corophium simile Shoemaker,Corophium acherusicum Costa,Lembos cf.L. websteri Bate andMelita appendiculata (Say). Densities of amphipods inMicroclona prolifera andHalichondria bowerbanki usually exceeded those inLissodendoryx isodictyalis andHaliclona loosanoffi. Seasonal changes in amphipod dominance were however approximately the same in all sponge species. Winter dominance byCorophium spp., and on occasionLembos spp., is followed by spring dominance byMelita appendiculata and summer dominance byColomastix halichondriae. Harsher winter conditions in 1976–77 apparently resulted in more reduced populations of various sponge species as well asColomastix halichondriae andLeucothoe spinicarpa when compared with the following winter. With some exceptions during the winter, amphipod density inMicrociona prolifera generally decreased as sponge size increased. The range of gammarid amphipod densities inMicrociona prolifera was 128–724 individuals per 5 g (40.3 cm3) of sponge. 相似文献
11.
A two-year trawl study of Laguna Joyuda, Puerto Rico, a small, polyhaline lagoon with restricted oceanic exchange, yielded 803 crabs belonging to sixCallinectes species.Callinectes danae was the most abundant (35.7%), followed byC. sapidus (21%),C. ornatus (12.6%),C. bocourti (12.1%),C. exasperatus (1.2%), andC. larvatus (0.4%). Abundances of different species differed more spatially than temporally despite very homogeneous salinities.Callinectes bocourti andC. sapidus were most abundant furthest from the lagoon’s inlet, whileC. danae andC. ornatus were most abundant near the inlet and in the center of lagoon. Juveniles were least abundant in the center of the lagoon. Size frequencies of most species showed common trends with high percentages of small crabs furthest from the inlet, and high percentages of larger crabs near the inlet and central parts of the lagoon. Distributional patterns appear to be a result of complex interactions of habitat preferences and intra- and interspecific interactions among the crabs. 相似文献
12.
Ten species, including crustaceans, molluscs and fish, were examined for predacious activity onZostera marina L. seeds and seedlings. Predation was examined initially by offering seeds or seedlings as a sole food source for a maximum period of one week. Species exhibiting predation of 10% or more of the seeds or seedlings were tested further with bits of clam or scallop as an alternative food source. In these experiments, animals were tested in each of three conditions: 1) alternative food plus seeds or seedlings; 2) alternative food alone; 3) seeds or seedlings alone. In the initial experimentsOvalipes ocellatus, Pagurus longicarpus, andPanopeus herbstii preyed on seeds, andIlyanassa obsoleta, Littorina littorea, andP. longicarpus preyed on seedlings. Limited predation occurred, however, when these animals were presented with seeds or seedlings plus an alternative food. These data suggest that several common crab and snail inhabitants of eelgrass meadows are capable of preying on eelgrass seeds and seedlings, but that this activity may be influenced by the availability of an alternative food source. 相似文献
13.
The effect of temperature and salinity on numbers of luminescent bacteria present in waters of the Mystic (Conn.) River estuary was evaluated. Counts decreased with decreasing salinity; none were detected at freshwater stations. A population maximum of 35 per ml was noted at the highest salinity station (30±2‰). Highest counts were observed during winter and spring and lowest numbers occurred during summer and fall months. Isolates (111) were identified and compared with previously-described luminescent bacteria; i.e.,Beneckea (Vibrio) harveyi, Photobacterium (V.) fischeri, P. phosphoreum, andP. leiognathi. All species were isolated but distinct seasonal differences were noted.P. (V.) fischeri andB. (V.) harveyi represented 93% of the luminous population on an annual basis. Only the former was found during the period December through March (highest count 7 per ml) whileB. (V.) harveyi was the dominant species noted between May and October (maximum count 11 per ml).P. leiognathi andP. phosphoreum were found only during July and August as 7% of the total luminous population. All isolates grew at NaCl concentrations between 6 and 30‰; none grew below 6‰ 相似文献
14.
Plant pigment decay constants were determined for four macrophytes collected from the Hudson Estuary.Typha angustifolia andScirpus fluviatilis were used as representatives of emergent aquatic vegetation (EAV), andPotamogeton sp. andVallisneria americana were used to represent submerged aquatic vegetation (SAV). Litter bags were maintained in an environmental chamber in the dark for 104 d. The fastest rate of total mass loss was in the SAVV. americana and slowest in the EAVT. angustifolia. Changes in carotenoid and chloropigment concentration resulting from microbial and meiofaunal heterotrophy in each of the macrophytes were quantified using reverse-phase, high-performance liquid chromatography (RP-HPLC) techniques. Chlorophyllc and the carotenoid, fucoxanthin, provided useful biomarkers in determining the presence of epiphytic diatom growth, which only occurred on the SAV. The highest concentrations of phaeophorbidea, commonly used as an indication of metazoan grazing, were found in the SAVV. americana. Low concentrations of phaeophorbidea in the SAVPotamogeton sp. indicate inefficient use of this SAV by meiofaunal grazers. Lutein decayed slower than all other carotenoids in both EAV and SAV. Microcosm studies such as this are necessary to further understand the mechanisms and kinetics of photosynthetic pigment transformations in natural systems. 相似文献
15.
Richard L. Rose 《Estuaries and Coasts》1984,7(2):128-132
Four polymorphic loci in seven natural oyster (Crassostrea virginica Gmelin) populations of the Chesapeake Bay were analyzed by protein-gel electrophoresis for genetic variation. Samples of about 100 each were taken in 1977 along environmental gradients from stations in the James and Potomac rivers. The distribution of genotypes at four loci for each of the stations was nog significantly different from Hardy-Weinberg expectations. At two loci (Pgi andLap-2), a pool of all seven stations was also in equilibrium. Significant genetic differentiation between rivers was detected for two other loci (Pgm-1 andLap-1), and frequency of one genotype (Lap-1 95/95) was significantly correlated with mean temperature over the water monitoring period (1972–1977). 相似文献
16.
The feeding habits of several fish species in a water reservoir of the Ria Formosa, Portugal, that has similar ecological characteristics to the outside tidal channels, were studied and compared with food availability. The gilthead seabream (Sparus aurata), the most abundant fish species, mainly selected gastropods and bivalves, although occasionally fish and small crustaceans such as tanaids, ostracods, and cumaceans were also selected. Polychaetes, although abundant in the environment, were not particularly selected by any of the fish species studied. The diets of all the species studied were characterized by a large variety of prey, allowing them to survive in environments of low diversity and poor stability, such as coastal lagoons. These fish are largely benthic feeders, essentially eating the epimacroinvertebrates and endomacroinvertebrates and, occasionally, fish.Diplodus vulgaris andDiplodus annularis preferentially selected gastropods and small crustaceans.Spondyliosoma cantharus generally preyed on crustaceans, including the highly mobile epifauma, the mysids, and decapods.Halobatrachus didactylus andAnguilla anguilla, had very diversified diets that included fish.Mullus barbatus were found to have selected all groups of crustaceans and also bivalves. Wrasses, gobies, andDiplodus sargus, all small-sized fish, singled out small crustaceans, gastropods, and bivalves. The Sparids were the least specialized predators, with broader niches than the other species. They preferentially selected molluscs, which were abundant in the environment. A large overlap of diets was observed and competition may be important when fish biomass is high. 相似文献
17.
David L. Meyer 《Estuaries and Coasts》1994,17(3):674-679
The abundances of the xanthid crabsPanopeus herbstii andEurypanopeus depressus were examined relative to surface oyster shell cover, surface oyster cluster volume, subsurface shell content, substrate sand and silt composition, and oyster reef elevation. During August 1986 through July 1987, xanthid crabs were collected monthly from twelve 0.25 m2×15 cm deep quadrats, during low tide, from intertidal oyster reefs in Mill Creek, Pender County, North Carolina, USA, with respective quadrat details recorded. The abundance ofP. herbstii, and to a lesser degreeE. depressus, was positively correlated with surface shell cover. The abundance ofE. depressus, and to a lesser degreeP. herbstii, was positively correlated with surface cluster volume. The majority ofP. herbstii inhabited the subsurface stratum of the oyster reef, whereas the majority ofE. depressus inhabited the cluster stratum. Seasonality (i.e., temperature) appeared to influence the strata habitation of both species, with a higher incidence of cluster habitation during warmer months and a lower incidence during colder months. Crab abundance was not related to other factors examined, such as subsurface shell, substrate sand and silt composition, or elevation within the oyster reef. The analyses show thatP. herbstii andE. depressus have partitioned the intertidal oyster reef habitat, withE. depressus exploiting surface shell clusters andP. herbstii the subsurface stratum. 相似文献
18.
The growth, morphology, and chemical composition ofHydrilla verticillata, Myriophyllum spicatum, Potamogeton perfoliatus, andVallisneria americana were compared among different salinity and light conditions. Plants were grown in microcosms (1.2 m5) under ambient photoperiod adjusted to 50% and 8% of solar radiation. The culture solution in five pairs of tanks was gradually adjusted to salinities of 0, 2, 4, 6, and 12‰. With the exception ofH. verticillata, the aquatic macrophytes examined may be considered eurysaline species that are able to adapt to salinities one-third the strength of sea water. With increasing salinity, the inflorescence production decreased inM. spicatum andP. perfoliatus, yet asexual reproduction in the latter species by underground buds remained constant. Stem elongation increased in response to shading inM. spicatum, while shadedP. perfoliatus had higher concentrations of chlorophylla. In association with high epiphytic mass, chlorophylla concentrations in all species were greatest at 12‰. The concentration of sodium increased in all four species of aquatic macrophytes examined here, indicating that these macrophytes did not possess mechanisms to exclude this ion. The nitrogen content (Y) of the aquatic macrophytes tested increased significantly with higher sodium concentration (X), suggesting that nitrogen may be utilized in osmoregulation (Y = X × 0.288 + 6.10, r2 = 0.71). The tolerance ofV. americana andP. perfoliatus to salinity was greater in our study compared to other investigations. This may be associated with experimental methodology, whereby macrophytes were subjected to more gradual rather than abrupt changes in salinity. The two macrophytes best adapted to estuarine conditions in this study by exhibiting growth up to 12‰, includingM. spicatum andV. americana, also exhibited a greater degree of response in morphology, tissue chemistry (including chlorophyll content and total nitrogen), and reproductive output in response to varying salinity and light conditions. 相似文献
19.
James P. Barry Mary M. Yoklavich Gregor M. Cailliet David A. Ambrose Brooke S. Antrim 《Estuaries and Coasts》1996,19(1):115-138
Food habits of the dominant fishes collected from 1974 to 1980 at eight locations in Elkhorn Slough, California, and the adjacent ocean were investigated. Epifaunal crustacea was the major prey group identified from stomach contents of more than 2,000 fishes, followed by epifaunal and infaunal worms, and molluscs. Overall, 18 fish species consumed 263 different prey taxa, ranging from 10 taxa to 125 taxa per fish species and including 99 crustacean, 56 polychaete, and 39 molluscan taxa. Mean prey richness was greatest at stations near the ocean and lowest at inshore stations. Detailed dietary data for all prey taxa were summarized as trophic spectra for each fish species. Trophic spectra represented functional groups of prey and were used for comparisons of dietary similarity. Cluster analyses, based on trophic spectra, resulted in four feeding guilds of fishes. Of 18 fish species, seven (Amphistichus argenteus, Leptocottus armatus, Embiotoca jacksoni, Clevelandia ios, Gillichthys mirabilis, Cymatogaster aggregata, andCitharichthys stimaeus) fed principally on epifaunal crustacea. Four species (Pleuronectes vetulus, Platichthys stellatus, Phanerodon furcatus, andMyliobatus californica) consumed mostly molluscs and infaunal worms. Two species (Psettichthys melanostictus andTriakis semifasciata) fed on mobile crustacea, and five species (Hyperprosopon anale, Engraulis mordax, Clupea pallasi, Atherinopsis californiensis, andAtherinops affinis) fed largely on zooplankton and plant material. Our results suggest that high food availability enhances the nursery function of imshore habitats, and emphasize the importance of invertebrate prey populations and the indirect linkage of plant production to the ichthyofaunal assemblarly marine immigrant species that are likely ‘estuarine dependent’. 相似文献
20.
Jinkai Xiao 《中国地球化学学报》1985,4(1):67-76
Microwave complex dielectric constants were measured with the cavity perturbation method for natural bitumens of various degrees of metamorphism as well as for bitumen samples subjected to thermal metamorphism under lab conditions. The results show a positive correlation between microwave complex dielectric constant and metamorphic degree and that the magnitude of variation in this parameter is greater than that of H/C,R max, free radical concentration,d 002 value, back-peak temperature in organic DTA and density. Microwave complex dielectric constant can be used as an indicator of oil-gas-generating threshold. For bitumen from oil- generating areas,ε′<5 andε″<0.070; and for that from oil-pyrolyzed gas areas,ε′=5?15 andε″=0.07?0.03. 相似文献