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1.
Effects of salinity on endogenous rhythm of the Manila clam, Ruditapes philippinarum (Bivalvia: Veneridae) 总被引:1,自引:0,他引:1
The Manila clam Ruditapes philippinarum, an intertidal bivalve, was exposed to different salinity regimes (from 31.0–31.7‰ down to 20‰, 15‰, 10‰, 5‰), and the endogenous
rhythm in its oxygen consumption was studied using an automatic intermittent-flow respirometer. When exposed to salinities
reduced from 31.5‰ to 20‰ and 15‰ under otherwise constant conditions, the clams recovered a clear endogenous circatidal rhythm
in their oxygen-consumption rate after having dampened periods of 12 h and 48 h, respectively. At salinities less than 10‰,
however, the oxygen-consumption rate was depressed greatly at the beginning of the experiment for about 36 h and then increased
to a level higher than normal, but the rhythm of oxygen consumption was not recovered. The results of this study indicate
that the Manila clam, a euryhaline organism, cannot maintain a normal metabolic activity at a salinity lower than 15‰. All
clams were dead after exposure at a salinity of 5‰ for 7 days.
Received: 28 February 2000 / Accepted: 26 August 2000 相似文献
2.
Juvenile lesser blue crabs, Callinectes similis Williams, were exposed to a range of salinities for measurement of survival and bioenergetics. Effects of salinity on survival
were determined by exposing juvenile crabs to salinity treatments ranging from 0 to 74‰. All crabs survived 21 d of exposure
to 5 and 45‰S. The 21 d LC50 values for salinity tolerance (calculated from survival data) were 2.6 and 60.8‰S at low and high salinities, respectively.
Energy-budget components and scope for growth were determined for crabs exposed to 2.5, 10, 25, 35 and 50‰S. Energetic absorption
rates were highest at 2.5 and 35‰S. Energetic expenditure rates (energy lost to respiration and excretion) were greatest at
2.5‰S, and decreased as salinity increased. Respiration constituted the majority of energetic expenditure at all salinities
(92.3% average). Scope for growth was significantly affected by salinity and was highest in crabs exposed to 35‰S. Increased
respiration at low salinity may indicate that C. similis incurs greater costs due to osmoregulation. The results of this study indicate that C. similis is capable of surviving and growing in waters with salinities as low as 10‰.
Received: 10 January 1997 / Accepted: 11 February 1997 相似文献
3.
The endogenous rhythm of oxygen consumption in juvenile spotted sea bass (Lateolabrax sp.) was measured to test the effects of sudden changes in salinity on the metabolic activity. Mean oxygen consumption rates
of this euryhaline fish decreased by 13.5 to 16.0% and 25.3 to 36.4% when they were transferred from 31.5 to 15‰ seawater
and to fresh water (0‰), respectively. The maximum rate of oxygen consumption was observed between 18:00 and 19:00 hrs local
time, 1 to 2 h before sunset, even though they were kept in constant darkness. The peaks of oxygen consumption occurred in
23.2- and 23.3-h intervals, which correspond with a circadian rhythm, as revealed by maximum entropy spectral analysis. A
markedly weakened rhythm in oxygen consumption occurred from 8 to 10 d after onset of the experiments. This study indicates
that spotted sea bass can withstand sudden drops in salinity from 31.5‰ to fresh water, and yet maintain a regular though
somewhat dampened endogenous rhythm of oxygen consumption.
Received: 16 June 1997 / Accepted: 3 February 1998 相似文献
4.
The importance of salinity experienced during embryonic development and initial larval biomass on larval growth was studied
in the South American estuarine crab Chasmagnathus granulata. Ovigerous females were maintained at three salinities (15, 20, and 32‰) from egg laying to hatching of zoea l. Larvae from
all treatments were reared under constant conditions of photoperiod (12∶12), temperature (18°C), and salinity (first instar
at 20‰, subsequent instars at 32‰). Biomass was measured as dry weight, carbon, and nitrogen content per individual at egg
laying, hatching of zoea l, premoult zoea l, and zoea 4, and in 8-day-old megalopa. From hatching to premoult zoea 4, biomass
was higher for larvae from prehatching salinities of 15 and 32‰. There was a significant positive correlation between biomass
at hatching and at premoult zoea l and zoea 4. Accumulated biomass during zoeal stages tended to be higher for larvae from
broods with higher biomass at hatching, although this trend was not always significant. Zoea 4 either directly metamorphosed
to megalopa or moulted to zoea 5, following, respectively, a short or long developmental pathway. The proportion of zoea 4
that followed the long pathway was negatively correlated with biomass of zoeal stages. Biomass at hatching was correlated
with biomass of megalopae developed through the short pathway, although it was not correlated with the accumulated biomass
at this stage. Megalopae developed through the long pathway (i.e. metamorphosed from zoeae 5) had higher biomass than those
from the short pathway. The present results suggest that prehatching salinity and initial egg and larval biomass can be very
important for larval growth.
Published online: 9 August 2002 相似文献
5.
C. T. Achuthankutty Y. Shrivastava G. G. Mahambre S. C. Goswami M. Madhupratap 《Marine Biology》2000,137(1):19-22
Effect of salinity on the feeding rate and parthenogenetic reproduction of asexual females of the cladoceran Diaphanosoma celebensis Stingelin was studied. Short-term (10 h) grazing experiments were conducted using Isochrysis galbana as feed at 5, 17, 25 and 30 psu salinity. Gut pigment concentration showed a significantly higher rate of feeding at lower
salinities. Survival, growth, maturity attainment and neonate production of asexual females reared in the above four test
salinities indicated preference for lower salinities (5 and 17 psu). The mean size of adult females decreased from 909 to
593 μm, mean life span from 24 to 5 d, mean neonate production from 12 to 2 and mean size of neonates from 434 to 400 μm as
the salinity increased from 5 to 30 psu. Salinity variations also affected the size and age of primiparous females. Resting
egg formation and sexual reproduction did not occur at the tested salinities. The results indicate that D. celebensis is adapted to low saline, estuarine environments.
Received: 14 January 2000 / Accepted: 24 March 2000 相似文献
6.
The marine planktonic diatom Chaetoceros anastomosans, which was isolated from Sagami Bay, was used for a study of resting spore formation mechanisms in batch culture experiments.
Vegetative cells could grow at salinities ranging from 20.7 to 45.5‰, and resting spore formation was enhanced significantly
in nitrate-depleted, high salinity media (40.0 to 45.5‰). The rate of resting spore formation (1.9 d−1) was comparable to the specific growth rate (1.8 d−1) of vegetative cells in the exponential growth phase in normal salinity medium. The size of resting spores formed under high
salinity conditions was smaller than that of spores formed in normal salinity media. Unlike vegetative cells, resting spores
seemed to possess some mechanisms to survive over a wider range of salinities by resisting bacterial attacks on their cell
walls.
Received: 4 August 1996 / Accepted: 27 August 1996 相似文献
7.
We examined larval response to a range of sharp haloclines and determined the effect of dietary conditioning on that response
in the sea urchins Echinometra lucunter and Arbacia punctulata. We reared larvae in the laboratory under a high or low concentration of either single (Isochrysis galbana) or mixed (Isochrysis galbana, Dunaliella tertiolecta, Thalassiosira weissflogii) microalgal species. For both species of sea urchins, rate of larval development was faster and age-specific larval length
and width were greater in high-ration than low-ration diets. We examined the distribution of two- and four-arm larvae of E. lucunter from each diet treatment and of four-arm larvae of A. punctulata from the high-ration diets in cylinders with experimentally constructed haloclines. In three of the halocline treatments,
the salinity of the bottom layer was 33‰ and that of the top layer was 21, 24 or 27‰ (21/33, 24/33 and 27/33) and in a fourth
one, the salinities of the bottom and top layer were 30 and 21‰, respectively (21/30). The position of larvae in the cylinders
varied with the steepness of the halocline and with dietary conditioning for both sea urchin species and all developmental
stages tested. Significantly more larvae crossed the haloclines into water of 24 and 27‰ salinity than into water of 21‰ salinity.
We observed an effect of diet on the position of larvae in the cylinders, and that effect varied among halocline treatments
for both species. The proportion of larvae of E.lucunter that crossed the halocline was greater in low- than high-ration diets in the 24/33 and 27/33 treatments. Position of four-arm
larvae in the cylinders also varied with food quality in high-ration diets: for E.lucunter in the 24/33 treatments, and for A.
punctulata in the 21/30 treatments, more larvae from the single- than from the mixed-species diets were present above the halocline.
Salinity in the adult habitat during most of the active reproductive period ranged from 15 to 40‰. We showed that larvae can
respond to gradients in salinity, and therefore can remain within a water mass of higher salinity overlying the adult habitat.
However, survival of poorly fed larvae may be increased if they are introduced into a new water mass and carried away from
a nutritionally poor environment.
Received: 9 July 1997 / Accepted: 12 January 1998 相似文献
8.
The influence of salinity on the time elapsed between two successive molts and the size reached after each molt were studied
at 30, 21, 12 and 3‰S in juveniles of two co-occurring grapsid species, Cyrtograpsus angulatus and C. altimanus, cultured under identical conditions of temperature, photoperiod and food. Juvenile growth patterns were compared between
these species (which differ in size-at-maturity and maximum size). C. angulatus grew faster than C. altimanus, reflecting a higher increment per molt and a shorter intermolt period. A significant difference existed between the number
of instars preceding the size of maturity in both species: >11 in C. angulatus, 6 in C. altimanus. There was evidence of a differential effect of low salinity on growth. By the end of the experiment, individuals of both
species were smaller at the lowest salinity (3‰) tested; the largest crabs developed at 21‰ (C. angulatus) and 30‰ (C. altimanus). The size difference between the “optimal” and the less suitable salinities in the sixth crab instar was 12.4% in C. angulatus and 35% in C. altimanus. During early juvenile development (Crab Instars 1 to 4), there were slight differences in intermolt period among salinities
in C. angulatus, but large differences in C. altimanus. The longest intermolt period of C. altimanus was at 3‰S and the shortest at 30‰S. In the following instars (5 to 10 in C. angulatus and 5 to 6 in C. altimanus), the longest intermolt period occurred at 21‰S, the shortest at 3‰S, in both species. Interspecific differences in response
to low salinities may explain why C. angulatus occurs throughout a whole temperate coastal lagoon, whereas C. altimanus is restricted to its mouth.
Received: 12 July 1998 / Accepted: 24 February 1999 相似文献
9.
The functional response of the aspects of reproductive success of a southwestern Baltic population of Acartia tonsa (Copepoda: Calanoida) was quantified in the laboratory using wide ranges in temperatures and salinities. Specifically, daily
egg production (EP, # female−1 day−1) was determined for 4 or 5 days at 18 different temperatures between 5 and 34°C and the time course and success of hatching
were evaluated at 10 different temperatures between 5 and 23°C. The effect of salinity (0 to 34 psu) on egg hatching success
was also examined. The highest mean rates of EP were observed between 22 and 23°C (46.8–50.9 eggs female−1 day−1). When studied at 18 psu, hatching success of eggs increased with increasing temperature and was highest (92.2%) at 23°C.
No hatching was observed for eggs incubated at low temperatures (≤12°C) that were produced by females acclimated to temperatures
≤10°C indicating a possible thermal threshold between 10.0 and 13.0°C below which only the production of diapause (or low
quality) eggs exists in this population. When tested at 18°C, the hatching success of eggs incubated at 15 different salinities
increased asymptotically with increasing salinity and was maximal (81.4–84.5%) between 17 and 25 psu. The high reproductive
success observed over wide ranges in temperatures and salinities in this Baltic population demonstrates one of the mechanisms
responsible for the cosmopolitan distribution of this species within productive, estuarine and marine habitats. 相似文献
10.
Modulation of the free amino acid pool and protein content in populations of the brine shrimp Artemia spp. 总被引:3,自引:0,他引:3
S. Helland G. V. Triantaphyllidis H. J. Fyhn M. S. Evjen P. Lavens P. Sorgeloos 《Marine Biology》2000,137(5-6):1005-1016
Free amino acid (FAA) and protein content were measured in various developmental stages of Artemia franciscana, from cysts to Instar III metanauplii. In addition, decapsulated cysts of 15 Artemia populations from different localities were compared with respect to their FAA and protein content. Furthermore, the content
and composition of the FAA pool were modulated by hatching the cysts at various salinities, and by enriching the nauplii with
algae or a lipid-enrichment emulsion. The FAA content increased threefold from cysts to nauplii, and Instar III metanauplii
contained nearly 50% taurine of total FAA. Cysts of A. franciscana were found to contain one-third the amount of FAA compared to the other Artemia species investigated. The content and pool composition of FAA was successfully modulated in 11 of 13 populations, where by
the content of FAA was significantly increased when hatched at high salinity. Finally, enrichment elevated the content of
FAA and changed the pool composition, thereby showing a dietary effect. Algal enrichment also increased the protein content.
Received: 27 September 1999 / Accepted: 17 July 2000 相似文献
11.
Valerio Matozzo Marta Monari Jurgen Foschi Gian Paolo Serrazanetti Otello Cattani Maria Gabriella Marin 《Marine Biology》2007,151(3):1051-1058
In the present study, the effects of differing salinities on some important functional responses of haemocytes from the clam,
Chamelea gallina, were investigated. The animals were kept for 7 days at 28‰ (hyposalinity), 34‰ (control) and 40‰ salinity (hypersalinity),
and total haemocyte count (THC), haemocyte volume, phagocytosis, lysozyme-like activity (in both haemocyte lysate and cell-free
haemolymph) were measured. The survival-in-air test was also performed. Clams kept at 28‰ showed significantly increased THC
with respect to animals kept at 34 and 40‰. The analysis of haemocyte size frequency distribution highlighted that in clams
kept at 28‰ the haemocyte fraction of about 5 μm in diameter and 50–100 femtolitre in volume increased markedly. Conversely,
in animals kept at 40‰ an increase was observed in the haemocyte fraction having about 8–10 μm diameter and 400–500 femtolitre
volume. Higher phagocytic activity was recorded in haemocytes from control clams, with respect to that of clams kept at 28
and 34‰. Lysozyme-like activity in haemocyte lysate was shown to increase significantly in animals kept at 28‰ with respect
to that of clams kept at 40‰, whereas enzyme activity in cell-free haemolymph from clams kept at 34‰ was significantly higher
with respect to that of clams maintained at 40‰. A relationship between phagocytosis and lysozyme secretion is suggested.
The resistance to air exposure of clams kept at 28 and 40‰ was shown to decrease significantly; LT50 values fell from 7 days in clams kept at 34‰ to 4 and 5 days in those kept at 28 and 40‰, respectively. Results demonstrated
that salinity values far from 34‰ affects the functional responses of haemocytes and reduce the resistance of clams to exposure
to air. 相似文献
12.
S. G. Cheung 《Marine Biology》1997,129(2):301-307
Physiology (oxygen consumption and ammonia excretion) and behaviour (feeding and activity) of the intertidal gastropod Nassarius festivus (Powys) at five different salinities [15, 20, 25 (control), 30 and 35‰] were studied for 4 weeks. Oxygen consumption and ammonia
excretion rates were reduced immediately after salinity was either elevated or reduced. Subsequently, both rates were increased
while the O:N ratio was decreased at all salinities, including the control, in the first 2 weeks and then levelled off. Such
changes were probably attributed to osmotic adjustment and reproductive activity. Activity and feeding were reduced at low
salinity, particularly in the first week. Reproductive output, in terms of the total number of egg capsules and the mean number
of eggs per capsule, was also lowered at reduced salinities. Nevertheless, individuals at all salinities are able to maintain
a positive energy balance. Results are discussed with respect to the distribution of N. festivus in Hong Kong waters.
Received: 14 April 1997 / Accepted: 9 May 1997 相似文献
13.
Dry weight (DW), oxygen consumption, ammonia-N excretion, proximate biochemical composition (total protein, carbohydrate,
lipid, water and ash), and energy content (estimated from biochemical composition and by wet combustion) were determined in
early developmental stages of cultured Farfantepenaeus paulensis. Pooled samples from embryonic, larval and postlarval stages (at 26 ± 1 °C and 34 ± 1‰) were used for measurements. The study
focused on physiological and biochemical processes during transitional periods of ontogeny, such as hatching, lecithotrophic
and planktotrophic stages, metamorphosis, and the attainment of a benthic existence in postlarva. DW showed higher increment
between protozoea I (PZ I) and mysis I (M I) than in the next mysid and postlarval stages. Individual rates of oxygen consumption
and ammonia-N excretion increased, while weight-specific rates presented significant reduction throughout development. Higher
weight-specific oxygen consumption was registered in nauplius III (N III) and PZ I, following a decrease in subsequent stages.
Postlarval stages PL V–VI and PL X–XII exhibited the lowest values among the stages studied. Weight-specific excretion was
high in N III and protozoeal stages, with maximum values in PZ II, while the following stages were marked by lower rates.
O:N ratios indicated higher protein catabolism in the stages between egg and M I and a shift to more lipid utilization close
to metamorphosis. Water content was higher in the protozoeal stages and decreased afterwards. Higher percentages of protein,
lipid and carbohydrate (%DW) were observed in egg and nauplius stages. Protein and lipid decreased from the egg through the
naupliar and protozoeal stages, rising again in mysis stages. Lipid content (%DW) decreased in PL V–VI and PL X–XII. Lipid:protein
ratios showed an increase of the importance of lipid between PZ III and M II. Carbohydrates represented a minor fraction of
body composition, and ash percentages increased from egg to a maximum in PZ II, decreasing in subsequent stages. Energy content
determined by wet combustion or calculated by energy equivalents presented the same trend throughout development, varying
similarly to protein. Protein was the main energy contributor to body energy in all stages, while the importance of lipid
was higher in egg and early naupliar stages. Trends observed in metabolic rates and body composition may be associated to
morphological and behavioral changes during the early stages of penaeid development, such as the transition from herbivory
to omnivory, and the adoption of a benthic existence. Different ontogenetic energy strategies contribute to succeed through
such diverse type of development.
Received: 4 July 2000 / Accepted: 6 December 2000 相似文献
14.
Environmental salinity is important in defining Brachionus plicatilis sibling species distributions. However, while salinity influences distributions, sibling species often co-exist. Three different mechanisms potentially account for the partial co-occurrence of sibling species: (1) siblings have differing salinity tolerances that partially overlap; (2) siblings physiological tolerances may be commonly broad, but relatively small differences in tolerances differentiate distributions via interactions e.g. competition; or (3) siblings distributions may be influenced by physical factors other than salinity. Here, we assess the extent of salinity tolerance in three B. plicatilis sibling species (B. plicatilis 6TUR, B. plicatilis IOM and B. rotundiformis 6TOS) by measuring population growth rate (μ, day−1) and egg development time in response to salinity (5–60‰) and salinity fluctuations (≤ Δ40‰). Sibling species were identified by analysis of the mitochondrial COI gene, and salinity responses were compared by regression analysis. Responses differed significantly between siblings, although the broad trends were similar. Positive growth occurred at all salinities, and highest growth rates ranged between 0.93 and 1.08 day−1 at 16–18‰. Rapid changes in salinity reduced growth rates, but net mortality occurred only in one treatment (100% mortality on transfer from 10 to 40‰). Egg development time was largely invariant with salinity except for B. plicatilis IOM and where rotifers were transferred from 30 to 60‰. We indicate that several siblings are similarly euryhaline and tolerate salinity fluctuations. Undoubtedly, wide tolerances in B. plicatilis are adaptations to ephemeral and seasonally variable habitats. Given common broad salinity tolerances, it is unlikely that the differential distributions of sibling species are a direct result of physiological constraints. Instead, we illustrate using a simple model that subtle differences in physiological tolerances may have important impacts on interactions between sibling species, which may in turn influence distributions. 相似文献
15.
A stow net (90 m2 opening) was used, at regular intervals between July 1989 and June 1993, to collect fish over ca. 4 h on both the flood and
ebb tides at five sites distributed at regularly spaced distances throughout the Elbe Estuary. Overall, 53.4% of the species
were marine, and some of these were abundant, e.g.Clupea harengus, Pleuronectes flesus, Pomatoschistus minutus, Merlangius merlangus and Sprattus sprattus. However, in terms of number of individuals, such species contributed only 9.1%, compared with 90.0% by anadromous species,
which was predominantly due to exceptionally high catches of Osmerus eperlanus. The ichthyofaunal compositions on the flood and ebb tides were similar, even downstream where salinities change markedly
during each tidal cycle. Although this is probably due in part to groups of fish being swept first upstream on the flood tide
and then back downstream on the ebb tide, several species clearly tended to occupy particular regions of the estuary. Each
year the species composition changed sequentially from the most downstream site (max. salinity=ca. 31.4‰) to the most upstream
site (max. salinity=ca. 1.5‰), mainly as a result of a sequential decline in the number and abundance of marine species and
a progressive increase in the contributions of both anadromous and freshwater species. However, the marine species diagnostic
of differences in the compositions among regions varied between years. Thus, for example, the diagnostic species for the downstream
sites were C. harengus and M. merlangus in 1990/1991 and S. sprattus in 1992/1993, reflecting differences in the recruitment strengths of these marine species in the two years. The ichthyofaunal
composition exhibited pronounced annual cyclical changes in each region and thus occurred irrespective of whether or not the
salinity in a region underwent pronounced changes during the year. This cyclicity was attributable to intra-annual variations
in the times of recruitment of certain marine species, particularly in the downstream region, and to seasonal migrations of
diadromous species into each region, as well as to the movements of freshwater species into the upstream region in winter
and early spring.
Received: 18 November 1999 / Accepted: 25 October 2000 相似文献
16.
The combined effects of salinity and temperature on survival and growth of larvae of the mussel Mytilus edulis (L.) were studied. The effects of salinity and temperature are significantly related only as the limits of tolerance of either factor are approached. Survival of larvae at salinities from 15 to 40 is uniformly good (70% or better) at temperatures from 5° to 20°C, but is reduced drastically at 25 °C, particularly at high (40) and low (20) salinities. Larval growth is rapid at a temperature of 15 °C in salinities from 25 to 35, at 20 °C in salinities from 20 to 35. Optimum growth occurs at 20 °C in salinities from 25 to 30. Growth decreases both at 25° and 10 °C; the decline is most drastic at high (40) and low (20) salinities.Part of a study completed at the Bureau of Commercial Fisheries, Biological Laboratory, Milford, Connecticut, USA, while on a UNESCO Fellowship. 相似文献
17.
Female mud crabs, Rhithropanopeus harrisii, carrying newly extruded eggs, were collected from the Petaluma River (San Francisco Bay Estuarine System, California, USA) in summer 1985, and exposed to factorial combinations of temperature (20°, 25° or 30°C) and salinity (2, 5, 15, 25, or 32%.). Upon hatching, dry weights of 12 to 15 h-old zoeae were determined. Subgroups of the remaining zoeae were transferred from hatching salinities to the salinities listed above and raised until metamorphosis to megalopa. Low salinities reduced zoeal dry weights by as much as 25%. Temperature played a secondary role in reduction of hatching weight of zoeae. Survival of larvae through zoeal development was best when hatching and rearing salinities were the same; in this case, overall survival increased with temperature. Both duration of zoeal development and megalopal dry weights were strongly influenced by temperature and rearing salinity, with only a small contribution from hatching salinity. The influence of hatching salinity was most obvious at extremes of the range tested. These studies indicate that physical conditions during embryogenesis profoundly influence subsequent larval development. Interpretation of experimental approaches to study ecophysiological adaptations of larval stages should not neglect the role of physical conditions during embryogenesis. 相似文献
18.
M. Nagaraj 《Marine Biology》1988,99(3):353-358
The calanoid copepodEurytemora velox was collected from rock pools at Castletown, Isle of Man, UK. Its optimum environmental requirements, particularly temperature and salinity, were determined, with a view to its possible future use as living food in intensive fish and shellfish farming. The species was cultured in 21 different temperature and salinity combinations. Investigations covered a period of two years from December 1983 to December 1985. Complete development from hatching to adult stage was followed in 21 temperature and salinity combinations. Nauplii suffered relatively high mortalities, indicating the sensitivity of this development stage to variations in temperature and salinity. Highest nauplii survival was observed in the combinations 15°C with 25 and 20 S and 20°C with 20 S, the highest copepodite survival at 10°C and 20 S. Lower salinities were tolerated better at higher temperatures and higher salinities at lower temperatures. Development time varied with the temperature and salinity combinations. Lower salinities at the lower temperatures of 10° and 15°C and both lower and higher salinities at 20°C prolonged development, particularly of the naupliar stage. Highest Q5 values (i.e., rate of change of development with a 5 C° increase in temperature) were recorded for the naupliar stage. Statistical analysis indicated that salinity influences the survival of both nauplii and copepodites; however, this effect is not linear. 相似文献
19.
Teegavarapu R. Rao 《Marine Biology》1974,24(2):155-162
Effects of salinity on embryonic development and survival were determined for eggs and larvae of the California killifish Fundulus parvipinnis Girard. Incubation salinities over the range of 5 to 14 S produced the shortest incubation period, maximum yolk-conversion efficiency, largest larval size at hatching, and maximum viable hatch. Various morphometric measurements of the newly-hatched larvae were influenced significantly by incubation salinity. Fertilization salinity also effected certain development criteria; in general, lower fertilization salinities resulted in shorter incubation periods and larger larvae at hatching. A salinity range of 5 to 14 S is anggested as a physiological optimum, and the known freshwater affinity of the species suggests that an eventual freshwater colonization by the California killifish is possible.Based on a thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, University of California, Irvine. 相似文献
20.
Experiments were performed to determine how ultraviolet radiation (UVR) in the environmentally relevant range affects development
of the sea urchin Strongylocentrotus droebachiensis (Müller) and whether mycosporine-like amino acids (MAAs), present in the early life stages, reduce UV-induced damage. Eggs,
embryos, and larvae contained five MAAs having absorption maxima ranging from 320 to 334 nm. Eggs contained principally shinorine
and porphyra-334, which absorb maximally at 334 nm and half-maximally at 312 and 348 nm, spanning much of the environmental
range of biologically effective UVR. Concentrations of MAAs remained constant in unirradiated embryos through the gastrula
stage, but decreased significantly in two-armed pluteus larvae. Daily exposure to combined photosynthetically active radiation
(PAR, 400–700 nm) and UVR did not affect the concentration of MAAs in these embryos up to the two-armed pluteus stage. Prism
larvae of sea urchins and the sand dollar Echinarachnius parma (Lamarck) did not accumulate shinorine from the surrounding seawater. Daily exposure of embryos to UVA (320–400 nm) and UVB
(295–320 nm) radiation in the presence of PAR induced delays and abnormalities during development, and removing UVB eliminated
this effect. Abnormalities in embryos included thickening of the blastoderm wall, filling of the blastocoel by abnormal cells,
exogastrulation, and formation of abnormal spicules. The percentage of embryos that developed normally was lower in batches
of embryos exposed to PAR + UVA + UVB, except in embryos from urchins maintained on MAA-rich diets. In all cases, the percentage
of PAR + UVA + UVB-exposed embryos that developed normally was positively related to the concentration of MAAs in eggs from
which the embryos developed. Thus, the MAAs found in S. droebachiensis embryos protect them against UVB-induced abnormalities during their development to at least the four-armed pluteus larval
stage.
Received: 8 May 2000 / Accepted: 29 September 2000 相似文献