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  • 1
    Electronic Resource
    Electronic Resource
    Relationships between effects of environmental temperature and seston on growth and mortality of Mytilus edulis in a temperate northern estuary (1980)
    Springer
    Marine biology 57 (1980), S. 147-156 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth and mortality of experimentally-rafted Mytilus edulis L. of known age at 7 locations in a northern estuary (Damariscotta River, Maine, USA) were related to environmental temperatures and to the presence or absence of various potential food sources. All particles were regarded as potential food substrates. Growth decreased appreciably at sites where water temperatures exceeded 20°C, but mussels survived a wide range of elevated temperature exposures, ranging from 0 to 149 degree-days in excess of 20°C. The maximum temperature was 25°C. Mortalities of mussels at all sites but did affect the extent of mortality, which increased abruptly in late summer, when water temperatures were declining. Differences in degree-days of exposure to elevated temperatures did not influence the timing of mortality, which occurred synchronously at all times, but did affect the extent of mortality, which ranged from 35 to 90%. The period of high mortality was preceded by a rapid decline in phytoplankton standing crop. Total particle concentrations decreased during this period, but the shift toward larger particles suggests that there was little, if any, decrease in total volume of material in the seston, at least through August. It is suggested that living phytoplankton provided the critical energy source for these mussels, and that the mortalities were caused by rapidly reduced ration at a time of metabolic stress. The role of temperature and the possible role of the gametogenic cycle are discussed. In addition, the feeding efficiency of M. edulis may have decreased during this period due to an increase in mean particle diameter. Chlorophyll was divided into a nannoplankton fraction (〈-20 μm) and a larger fraction (〉20 μm). A smaller size criterion for this distinction is proposed for future studies. The importance of nannoplankton to the primary production of this estuary and the role of nannoplankton and nannoplankton-sized particles in the diet of mussels in nature are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390733
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  • 2
    Electronic Resource
    Electronic Resource
    Larval dispersal of a deep-sea hydrothermal vent bivalve from the Galápagos Rift (1980)
    Springer
    Marine biology 57 (1980), S. 127-133 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The prodissoconch morphology of an unclassified mytilid from a hydrothermal vent on the Galápagos Rift indicates the presence of a planktotrophic larval stage with longrange dispersal capabilities. Recorded abyssal currents are probably sufficient to transport such larvae hundreds of kilometers. It is suggested that one or more aspects of the unusual biological or physico-chemical conditions (such as high microbial densities, elevated water temperatures, and hydrogen sulfide concentrations) encountered at vents, provide a stimulus to larval settlement. Such a behavioral response, perhaps coupled with a “gregarious settling” response, would provide a means of concentrating relatively sedentary organisms in and around these restricted, geographically isolated regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387378
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  • 3
    Electronic Resource
    Electronic Resource
    A statistical model relating horizontal seston fluxes and bottom sediment characteristics to growth of Mercenaria mercenaria (1989)
    Springer
    Marine biology 102 (1989), S. 95-105 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several field experiments have shown that bottom sediment type affects growth of the hard clam, Mercenaria mercenaria. A previous manipulative field experiment carried out within a moderate range of tidal current speed/seston concentration regimes in Great Sound, a coastal lagoon in southern New Jersey, USA, indicated that growth of M. mercenaria was more influenced by horizontal seston fluxes than sediment type. The present descriptive/correlative study was also conducted at Great Sound, during 1985 and 1986, and was designed to quantify the relationships between shell growth of M. mercenaria and a wide range of levels of tidal currents, seston, and bottom sediments. It showed: (1) near-bottom tidal currents and seston were best correlated with growth when combined as a horizontal seston flux rate, [i.e., current speed (cm s-1) x seston concentration dry wt cm-3=dry wt seston cm-2 s-1]; (2) the correlation between seston fluxes and growth was positive to some point, then became negative with further increases in seston fluxes; (3) sediment characteristics were correlated with growth; and (4) there may be an interaction between sediment characteristics and seston fluxes as they affect growth. These findings suggested a statistical model of the general form: $$\eqalign{ & SG = B_0 + B_1 (X_1 ) + B_2 (X_1 )^2 \cr & {\rm{ }} + B_3 (X_2 ) + B_4 (X_1 )(X_2 ) + E, \cr}$$ where SG=shell growth; B o=y-intercept; B i =coefficient of the ith term; X 1=mean horizontal seston flux; X 2=sediment characteristic; E=error term. Multiple regression techniques were used to determine values for the coefficients in the model, and associated R 2 values. R 2 values for models using various shell growth measurements, seston fluxes, and bottom sediment characteristics ranged from 0.69 (P=0.35) to 0.90 (P=0.07). Maximum growth occurred at moderate seston flux rates (e.g. 90 to 130 mg particulate organic matter cm-2 s-1) combined with sand sediments. Increased or decreased (relative to moderate rates) seston fluxes, and/or decreased grain size of the bottom sediments, resulted in reduced growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391327
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  • 4
    Electronic Resource
    Electronic Resource
    Longevity of subitaneous and diapause eggs of Centropages hamatus (Copepoda: Calanoida) from the northern Gulf of Mexico (1998)
    Springer
    Marine biology 131 (1998), S. 249-257 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Copepod resting eggs are abundant in the seabed of many bays and estuaries where they provide a potential source of recruits for growth of planktonic populations. In the northeastern Gulf of Mexico the copepod Centropages hamatus (Lillejeborg) occurs in the water column only during the late fall, winter and early spring. The species produces subitaneous and diapause eggs, and both egg types have been found in the seabed. We determined the longevity of these two egg types to ascertain their potential for contributing to the growth of the planktonic population and for sustaining a persistent egg bank. Eggs were collected from females and incubated in the laboratory under temperature and oxygen conditions chosen to simulate field conditions. The diapause eggs were also exposed to sulfide. The total hatching success of subitaneous eggs in two experiments declined from highs of 78 and 97% to zero after 60 and 90 d of exposure to anoxia. The total hatching success of diapause eggs that were exposed to anoxia for 90 d however was typically greater than 80%. Some diapause eggs hatched after being incubated under anoxia for 437 d. Diapause eggs survived longer at ambient field temperatures when incubated under anoxia (437 d) compared to normoxia (118 d). Exposure to sulfide did not result in greater mortality of diapause eggs compared to anoxia alone. Diapause eggs that were incubated at ambient field temperatures did not hatch when exposed to normoxia until the temperature dropped to 〈20 °C. The results of this study suggest that C.␣hamatus sustain a short-term reserve of subitaneous eggs in the seabed that provides recruits for the current year's population. The greater longevity of diapause eggs suggests that they sustain the seasonal reappearance of the species year after year in the northeastern Gulf of Mexico. However, the contribution of diapause eggs of C. hamatus from the Gulf of Mexico to a persistent egg bank is questionable since hatching ceased after 437 d.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050317
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of low oxygen concentrations on the hatching and viability of eggs of marine calanoid copepods (1992)
    Springer
    Marine biology 114 (1992), S. 241-247 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hatching of the eggs of four species of copepods, Acartia tonsa, Labidocera aestiva, Tortanus discaudatus, and Centropages hamatus was suppressed at oxygen concentrations less than 0.02 ml O2/l. When such eggs were subsequently exposed to normal oxygen concentrations, hatching varied among the species, indicating variability in the capacity of eggs to survive exposure to low oxygen. Incubation of eggs at low oxygen concentrations resulted in an increase in the duration of embryonic development. Experiments were conducted in closed systems and oxygen concentration was determined by thermal conductivity using gas chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349525
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  • 6
    Electronic Resource
    Electronic Resource
    Gene flow among vestimentiferan tube worm (Riftia pachyptila) populations from hydrothermal vents of the eastern Pacific (1994)
    Springer
    Marine biology 120 (1994), S. 33-39 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allozyme data are presented for six discrete populations of the giant hydrothermal vent tube worm Riftia pachyptila Jones, 1981 collected throughout the species' known range along mid-ocean spreading ridges of the eastern Pacific Ocean. Contrary to an earlier report, levels of genetic variation are relatively high in this species. Estimates of gene flow based on F-statistics revealed that dispersal throughout the surveyed region is sufficiently high to counter random processes that would lead to losses of genetic diversity and significant population differentiation. R. pachyptila, like other species of tube worms, displays considerable morphologic variation among populations, but this diversity is not reflected in allozyme variation. Vestimentifera, in general, appear to show extensive phenotypic plasticity. In the light of the available genetic data, caution is warranted when making inferences about the taxonomic status of collections based on morphological variation alone. A general decrease in estimated rates of gene flow between geographically more distant populations supports the hypothesis that dispersal in this species follows a stepping-stone model, with exchange between neighboring populations in great excess of long-distance dispersal. High levels of gene flow have been recorded in a variety of vent fauna and may be a prerequisite for success of species found in the ephemeral habitats associated with regions of sea-floor hydrothermal activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381939
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of anoxia on the viability of subitaneous eggs of planktonic copepods (1994)
    Springer
    Marine biology 121 (1994), S. 83-87 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of anoxia on the viability (as evidenced by hatching) of newly spawned and fully developed subitaneous eggs of three species of copepods, Acartia tonsa (Dana), Centropages hamatus (Lilljeborg), and Labidocera aestiva (Wheeler) was determined for eggs produced in the laboratory by adults collected from inshore waters of the northeastern Gulf of Mexico between January and August 1992. Hatching success decreased to 50% or less when eggs were exposed to oxygen concentrations 〈0.06 mll-1 for more than 12 d, except for newly spawned eggs of L. aestiva, which still showed 50% survival after 32 d of exposure to anoxia. For all three species, newly spawned eggs survived exposure to anoxia longer than fully developed eggs. The results indicate that the increasing occurrence of anoxia in estuarine and coastal waters could have a major impact on the population growth of these important food web organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349476
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  • 8
    Electronic Resource
    Electronic Resource
    Identification of archaeogastropod larvae from a hydrothermal vent community (1996)
    Springer
    Marine biology 124 (1996), S. 551-560 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dispersal is essential in order that endemic species living in ephemeral, patchy vent environments may persist over evolutionary time. Quantitative field studies of larval dispersal, however, require specieslevel identification of the larval forms because each individual must be distinguished from related vent species, and from non-vent species living in the surrounding deep-sea environment. Methods for culturing these larvae to an identifiable stage have not yet been developed. To solve the larval identification problem for the archaeogastropod molluscs (a prominent component of vent communities), we used a scanning electron microscope (SEM) to image shells of larvae collected in the water column near vents along the East Pacific Rise (9°40′ to 9°50′N; 104°W). Larval shell size, shape and ornamentation were compared to protoconchs retained in juvenile or adult shells of identified species, and used to assign five larval groups unequivocally to species (Cyathermia naticoides Warén and Bouchet, 1989; Neomphalus fretterae McLean, 1981; Clypeosectus delectus McLean, 1989; Rhynchopelta concentrica McLean, 1989; and Lirapex granularis Warén and Bouchet, 1989) and seven groups tentatively to species or genus [Lepetodrilus spp. (three groups); Gorgoleptis sp; Peltospira ?operculata McLean, 1989; and ?Melanodrymia sp. (two groups)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351036
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  • 9
    Electronic Resource
    Electronic Resource
    Extensive gene flow among mytilid (Bathymodiolus thermophilus) populations from hydrothermal vents of the eastern Pacific (1995)
    Springer
    Marine biology 124 (1995), S. 137-146 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Prior studies of the hydrothermal vent mussel Bathymodiolus thermophilus (Bivalvia: Mytilidae), provided conflicting predictions about the dispersal ability and population structure of this highly specialized species. Analyses of morphological features associated with its larval shells revealed a feeding larval stage that might facilitate dispersal between ephemeral vent habitats. In contrast, an allozyme study revealed substantial genetic differentiation between samples taken from populations 2370 km apart on Galápagos Rift (Latitude 0°N) and the East Pacific Rise (13°N). To resolve the discrepancy between these studies, we examined allozyme and mitochondrial (mt) DNA variation in new samples from the same localities plus more recently discovered sites (9° and 11°N) along the East Pacific Rise. Although analysis of 26 enzyme-determining loci revealed relatively low levels of genetic variation within the five populations, no evidence existed for significant barriers to dispersal among populations. We estimated an average effective rate of gege flow (Nm) of ≃ 8 migrants per population per generation. Two common mtDNA variants predominated at relatively even frequencies in each population, and similarly provided no evidence for barriers to gene flow or isolation-by-distance across this species' known range. Larvae of this species appear to be capable of dispersing hundreds of kilometers along a continuous ridge system and across gaps separating non-contiguous spreading centers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349155
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  • 10
    Electronic Resource
    Electronic Resource
    Hatching and viability of copepod eggs at two stages of embryological development: anoxic/hypoxic effect (1994)
    Springer
    Marine biology 119 (1994), S. 199-204 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of low oxygen concentrations on the hatching and viability of copepod eggs at two stages of embryological development were investigated. Fully developed eggs from Acartia tonsa (Dana) and Labidocera aestiva (Wheeler) collected between July and September 1991 at Turkey Point, Florida, USA, hatched at lower oxygen concentrations than newly spawned eggs given the same incubation periods. Since many of the newly spawned eggs subsequently hatched when exposed to normoxic conditions, it is likely that the exposure to low oxygen delayed embryonic development. At oxygen concentrations where no initial hatching occurred, the subsequent hatching success of fully developed eggs of A. tonsa was higher than that of newly spawned eggs, indicating that newly spawned eggs were more sensitive to low oxygen concentrations. No such difference was observed for the eggs of L. aestiva.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349557
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