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1.
The gonads of Serranus cabrilla (Linnaeus, 1758) from the Canary Islands were studied between September 1992 and July 1993. Macroscopic classification of
the maturity stages was compared with histolog ical classification of gonad characteristics, and the effect␣of the classification
method on the determination of the spawning season and size at maturity was investigated. Analysis of gonad organization and
development confirmed that this species is synchronously hermaphroditic. Ovarian-tissue development is asynchronous, and testicular
tissue consists of continuous spermatogonia. Six stages of oogenesis and five of spermatogenesis are described, based on differences
in staining and in size and on differences in the nucleus and cytoplasm structure as viewed through a light microscope. Two
types of atretic degeneration of eggs are also described. Agreement between macroscopic and histological staging was low,
although both methods provided similar results in spawning-season determination and size at maturity. The spawning season
of S. cabrilla is from February to July, with a peak in May. Fish size at first maturity (size at which 50% of all fish sampled are in relevant
maturity stage) is 152 mm standard length (SL), and size at mass maturity (size at which 95% of all fish sampled are in relevant
maturity stage) is 167 mm SL.
Received: 21 May 1996 / Accepted: 9 August 1996 相似文献
2.
The northern Pacific asteroid Asterias amurensis (Lütken) has been recently introduced to Tasmania and is now well-established in east and southeast Tasmania. This sea star
is conspicuous throughout the Derwent River estuary and is particularly abundant in the Hobart port area. Reproduction of
two populations of A. amurensis at Sullivans Cove and at Sandy Bay was investigated from August 1993 to October 1994 by gonadal histology and measurement
of the gonad index (GI). An intense period of vitellogenic and spermatogenic growth started in April, with the breeding condition
reached by June. In 1994, peak GI was recorded at Sullivans Cove in July and at Sandy Bay in August. Although these data indicated
that the Sullivans Cove population spawned before the Sandy Bay population, histological examination revealed that major spawning
activity occurred in both populations from July onwards. In the early part of the breeding season, gametogenesis proceeded
in parallel with spawning, with released gametes being replaced by continual gametogenesis. Maintenance of a higher GI during
the early part of the breeding season at Sandy Bay was due to prolonged gametogenic replacement at this site. Spawning continued
to October 1994, resulting in a sharp decline in the GI. The cyclic expansion and regression of the genital haemal sinus coincident
with germinal proliferation and growth, respectively, support the contention that haemal fluid provides nutrients for gametogenesis.
In Tasmania, A. amurensis experiences temperature and photoperiod regimes similar to those experienced by endemic populations of this species in the
north Pacific. Comparison of reproduction of A. amurensis in Japan and Tasmania at similar latitudes shows that gametogenesis of the northern and southern populations is 6 mo out
of phase. This phase shift provides evidence for photoperiodic regulation of gametogenesis in A. amurensis. The similar trend in sea-temperature regimes associated with the stages of gametogenesis in northern and southern populations
suggests that temperature also plays a modulatory role. Based on the periodicity of reproduction and the ontogeny of A. amurensis, the planktotrophic larvae of this species would be expected to be in the plankton for several months from the end of winter
through summer. Considering the highly fecund, dispersive life-history of A. amurensis, the southeast Tasmanian populations have considerable potential to serve as a seed source for establishment of new populations
of this asteroid elsewhere in Tasmania and in mainland Australia.
Received: 18 October 1996 / Accepted: 22 October 1996 相似文献
3.
M. D. Herrero-Pérezrul H. Reyes Bonilla F. García-Domínguez C. E. Cintra-Buenrostro 《Marine Biology》1999,135(3):521-532
The reproduction and growth of Isostichopus fuscus (Ludwig, 1875) at Isla Espíritu Santo, Baja California Sur, México from July 1992 to September 1993 and from August 1996
to July 1997 were analyzed. The reproductive cycle was monitored by using histological analysis. Five gonadal stages were
described according to cell types present in the gonad; undetermined, gametogenesis, maturity, spawning and post-spawning.
This holothurian reproduces annually during summer (July to September), when sea surface temperature reaches 27 °C. The gonad
index is related to the gonadal stages. The first sexual maturity for I. fuscus was calculated at 367 g (4 to 5 years old) according to the von Bertalanffy equation, and nearly all the specimens at Isla
Espíritu Santo were 5 to 7 years old (including some individuals over 35 years old). Data of the length–weight relationship
showed that I. fuscus grows allometrically at the studied site (b = 1.83). The mortality rate was relatively high (M = 0.51), indicating that in a typical cohort, 40% of the recruits does not survive the first year, and less than 20% reaches
maturity.
Received: 15 July 1998 / Accepted: 19 August 1999 相似文献
4.
Over a 3-year period (1996-1998), reproduction of the commercial sea cucumber Holothuria scabra (Jaeger, 1833) was investigated in the Solomon Islands to determine the spawning pattern and whether gametogenesis is continuous or seasonal. The gonad consisted of a single cohort of tubules that developed uniformly. Macroscopic examination of the gonads revealed that mature gametes were present throughout the year. Individuals with gonads at different stages of maturity were present in most samples. Partly spawned gonads were prevalent in females, whereas mature gonads were prevalent in males. The time at which the peak gonad index was recorded differed among years. Although gametogenesis was continuous, with a potential for prolonged gamete release, a period of enhanced spawning occurred during the dry season, from September to December. Maximum gonad indices were reached prior to and during this period of enhanced spawning. Histology revealed that gametogenesis reinitiated in partly spawned gonads, resulting in the presence of gametes at different stages of development in the gonad. The uniform growth of gonad tubules indicated that H. scabra does not conform to the progressive tubule recruitment model described for holothurian oogenesis. Continuous reproduction in H. scabra and prolonged availability of mature gametes would facilitate use of this species for aquaculture. 相似文献
5.
Experiments were conducted to determine the effect of four algal diets (Corallina spp., Gelidium pristoides, Ulva rigida and an equal volume mixture of these seaweeds) on growth and reproduction of the South African gastropod Turbo sarmaticus Linnaeus, 1758. The best growth rate of juveniles (up to 13.8 mm shell length and 34.26 g wet body weight increase in 12
months), reproductive fitness of mature specimens (gonad index up to 33%) and energy reserves (up to 4.76 mg glycogen/100 mg
foot tissue) were achieved when T. sarmaticus was fed U. rigida or a mixed diet. In addition, the gonad index of individuals fed these diets was almost twice that of similar-sized field
specimens. Juveniles fed Corallina spp. only, grew very little (only 2.4 mm shell length and 4.23 g wet body weight increase in 12 months). The reproductive
fitness of adults fed on such a diet was also poor (gonad index <4.5%) and energy reserves were low (<3.5 mg glycogen/100 mg
foot tissue). Along the southeastern coast of South Africa, T. sarmaticus has a distinct reproductive cycle with gametogenesis occurring from March/April until August/September, whilst maturity (gonad
index = 15%) was maintained until December, after which spawning occurred until March.
Received: 6 July 1998 / Accepted: 8 March 1999 相似文献
6.
Green sea urchins, Strongylocentrotus droebachiensis OF Müller, collected off the coast of New Hampshire, USA, in late February 1995, were brought into the laboratory and fed
an artificial diet ad libitum, and subjected to a photoperiod advanced by 4 months. During this study, temperatures and salinities
for experimental urchins mirrored those recorded at the collection site. We examined the effects of changes in feeding regime
and photoperiod on gametogenesis and compared the experimental urchins with those from the source population. During the 7-month
period, experimental urchins showed no detectable changes in mean test height or diameter. Experimental urchins had a significantly
higher gonad index (GI) in March, April and May (18 ± 6%) compared with field urchins in March (11 ± 3%). Subsequently, experimental
urchins had a mean monthly GI of 25 to 30%, while the mean GI for field urchins was 11 to 13%. Gonial cell mitosis and gametogenesis
occurred earlier in experimental male and female urchins compared with field urchins. Stereological and histological observations
and stage–frequency data showed that the ovaries of experimental urchins were large because of the accelerated development
of nutritive phagocytes, the volume fraction (V
v) of which was 89 to 90% of the gonad, while new vitellogenic primary oocytes occupied <1% V
v. In males, stereological and histological observations and stage–frequency data suggested a mobilization of materials from
the nutritive phagocytes beginning between June and August, i.e. earlier than in females, and, by September, new gametes occupied
a V
v of 49 ± 3% of the testes. Oocyte size–frequency distributions demonstrated that most primary oocytes were <80 μm in diameter
between March and September, suggesting that cold temperatures may be needed for completion of vitellogenesis. We describe
changes in the two principal cell types in the germinal epithelium of urchin gonads and indicate how knowledge of their population
dynamics may be useful in aquaculture applications.
Received: 21 February 1997 / Accepted: 3 June 1998 相似文献
7.
Reproduction in the sea urchin Centrostephanus rodgersii was examined in two types of habitats (“barrens”, i.e. habitats characterised by the high crustose coralline algal cover
typical of urchin-barren grounds, and by the absence of macroalgae; and “fringe”, i.e. habitats characterised by a high macroalgal
biomass and few C. rodgersii) at four locations in New South Wales. The four locations: the Solitary Islands, Sydney, Ulladulla and Eden, span the distribution
of C.␣rodgersii from the subtropics at its northern limit to temperate waters near its southern limit. Histology and estimates of gonad retrieval
rate (GRR) from January 1994 to October 1995 indicated that reproduction was synchronous at all locations. An increase in
the tempo of gametogenesis in May and onset of spawning in June at all locations is consistent with entrainment in response
to exogenous factors. Over the range studied, C. rodgersii experienced relatively similar daylength cycles and contrasting sea-temperature cycles. Short days and lunar conditions coinciding
with the solstice appear likely proximate cues for the onset of spawning. The major difference in reproduction among locations
was in the duration of spawning. In the southern parts of its range breeding occurred over a 5 to 6 mo period, whereas at
the Solitary Islands it lasted ≃1 mo. At most locations the GRRs were significantly higher in the fringe habitat than in the
barrens habitat. The lower reproductive output of urchins in the barrens habitat was attributed to the food-poor conditions
typical of this habitat. The developing fishery for C. rodgersii is likely to be most effective from March to early May. Urchins from barrens areas may not provide sufficient yield to warrant
harvesting.
Received: 29 October 1997 / Accepted: 18 May 1998 相似文献
8.
Seasonal trends in the gonad index (GI) of two widely separated populations of black teatfish, Holothuria whitmaei (formerly included in Holothuria nobilis), were investigated between Pacific (Great Barrier Reef) and Indian Ocean (Ningaloo Reef) coral reefs of Australia. Reproductive
activity followed a similar annual trend, with the GI of both populations peaking typically between April and June. Macroscopic
and histological analysis of Ningaloo Reef specimens revealed that large germinal tubules, positioned centrally on the gonad
basis, progressed through four maturity stages: growing (II); mature (III); partly spawned (IV); and spent (V). Growing tubules
dominated the central region of the gonad basis between January and March, followed by an increase in the number of mature
tubules throughout the GI peak (April–June). The progressive appearance of partly spawned and spent tubules between June and
October suggests that spawning in H. whitmaei continues intermittently over an extended period throughout the austral winter. The examination of the gonad structure of
sexually mature male and female specimens identified five tubule size classes in total (C1 to C5), each of differing physical and gametogenic status. In females, smaller C1 tubules located at the anterior edge of the gonad basis contained pre- to early vitellogenic oocytes. Larger C2 and C3 tubule cohorts, positioned centrally on the gonad basis, contained mid- to late-stage vitellogenic oocytes. Smaller C4 and C5 tubules, located at the posterior edge, contained only relict oocytes. Similar physical and gametogenic differences were
apparent between tubule cohorts in male specimens. We propose that these results, together with evidence of incomplete gonad
resorption over the austral summer, indicate that gonad development in H. whitmaei conforms to the predictions of the Tubule Recruitment Model (TRM). The TRM is reported rarely among tropical aspidochirotes,
and results presented here (1) provide the first direct evidence of this model in H. whitmaei, and (2) confirm that this species is one of the few winter-spawning tropical invertebrates. 相似文献
9.
Catalina T. Pastor-de-Ward Tamara Rubilar María E. Díaz-de-Vivar Ximena Gonzalez-Pisani Erica Zarate Marina Kroeck Enrique Morsan 《Marine Biology》2007,151(1):205-217
The starfish Cosmasterias lurida was sampled from the pier piles of Almirante Storni in the Golfo Nuevo, northern Patagonia, from November 2001 to November
2003. In this anthropogenically modified site there is an unusually abundant food supply of mussels and large aggregations
of starfishes. The reproductive cycle was studied by organ indices and histological examination of gonads. The highest gonad
index (GI) values were found in the summer (February–March), followed by a drop in GI values, indicating spawning. Histological
analyses indicated that gametogenesis takes place from June to January, sexual maturity occurred during the summer and spawning
occurred in April. The GI and pyloric caeca index (PCI) tended to have an inverse relationship, but this was only statistically
significant in males. However, biochemical analyses of the starfish indicated no transfer of nutrients between pyloric caeca
and gonads in either sex. In fact, simultaneous accumulation of carbohydrates was found in the pyloric caeca and gonads of
both sexes. 相似文献
10.
The endemic New Zealand echinoid, Evechinus chloroticus (Valenciennes), was sampled approximately monthly from September 1990 to October 1994 at three sites in Tory Channel, Marlborough
Sounds, New Zealand. These channel sites (outer, mid and inner) were up to 20 km from the open ocean and differed in their
shore type, exposure to wave action and macrophyte abundance. E. chloroticus showed an annual reproductive cycle at each site, with gametogenesis commencing in the late austral winter and spawning in
summer. Maximum gonad indices (reproductive potential) varied spatially, with the outer site generally having higher maximum
gonad indices than the inner site, and temporally, with maximum gonad indices occurring earlier in 3 of the 4 seasons at the
outer site than the inner site. The mid and inner sites showed much greater variation in maximum gonad indices (range 15.83
to 26.99% and 11.87 to 20.90%, respectively) than the outer site (range 19.31 to 22.95%). Reproductive output (weight of gametes
released per gram echinoid) also varied, with the different sites showing significantly different outputs in the different
years. A regression of maximum reproductive potential against reproductive output was significant ( p < 0.001), and had a positive slope with an r
2 of 0.79. While, the initiation of gametogenesis was relatively synchronous between sites and years, and is possibly cued
by increasing daylength, it progressed at different rates among populations. Spawning did show spatial and temporal variability,
occurring near the time of highest sea-surface temperatures (∼15 °C). The observed variations in reproductive cycle may be
related to small-scale variability in diet and environmental conditions. Furthermore, asynchronous spawning, variable spawning
duration, and variable reproductive output are likely to strongly influence annual recruitment variability in E. chloroticus, with different larval subpopulations contributing unequally in different years. The ecological consequences of this, both
for the ability of E. chloroticus to propagate itself in space and time and for the management of the developing E. chloroticus fishery in New Zealand, are discussed.
Received: 9 December 1998 / Accepted: 13 June 2000 相似文献
11.
The reproductive cycle of the sea urchin Centrostephanus rodgersii (Agassiz) was investigated in two populations, at Clovelly and Little Bay, in Sydney, New South Wales, Australia. C. rodgersii were collected at monthly intervals from February 1992 through January 1993. The reproductive cycle was determined by histological examination of oogenesis and spermatogenesis, monthly measurements of gonad index (GI), and induction of spawning by KCl injection. C. rodgersii has an annual reproductive cycle that was highly synchronous in both populations. From February to June, gametogenesis was accompanied by a decline in the amount of nutritive tissue in the gonads. The urchins were mature from June to September, with peak spawning between July and August, as indicated by a significant drop in GI. The breeding season of C. rodgersii therefore coincides with the lowest sea temperatures and the shortest days of the year. The gonads returned to the recovering condition within a month of spawning, with a substantial thickening of the nutritive layer along the gonad wall, and the GI returned to near pre-spawning levels. As a result, the spent phase was rarely found in C. rodgersii. With the exception of a significant decrease in the GI following spawning of urchins from the Clovelly population, the GI measurements did not show any distinct pattern through time. Specimens spawned in response to KCl injection from mid-May to early October, with the maximum response in July. Although all individuals sampled were at a similar stage of maturity at any one time, inter-site differences were seen with all of the methods used. Gonad indices from Little Bay were consistently higher and less variable than those from Clovelly for most of the year. The Little Bay population could also be induced to spawn for a longer period of time than could the Clovelly population. The breeding season of the Little Bay population appears to be longer than that of the Clovelly population. The relationship between size and sexual maturity was also examined. All C. rodgersii with a test diameter of >60 mm could be induced to spawn and produced viable gametes. C. rodgersii has been nominated for commercial exploitation in New South Wales, and the results of this investigation are used to make recommendations on the timing and size limits for a fishery utilising this species. 相似文献
12.
To assess the effects of both temperature and food ration on gonad growth and oogenesis of the green sea urchin, Strongylocentrotus droebachiensis (O.F. Müller), individuals collected December 1996 (winter experiment) and June 1997 (summer experiment) were maintained
for 3 months in one of four experimental treatments: (1) 3 °C and fed ad libitum (high ration), (2) 3 °C and fed one-seventh of the maximum ration (low ration), and (3) 12 °C and fed the high ration; (4) 12 °C and fed
the low ration. All individuals were fed an artificial diet and exposed to only 1 h of light every day. At the end of both
experiments, mean gonad indices of sea urchins fed the high ration had increased significantly (11–24% and 6–19% in the winter
and summer experiments, respectively), while the gonad indices of individuals fed the low ration did not change. At the high
ration (both experiments), the increase in gonad index of sea urchins occurred primarily as the result of a significant increase
in the mass of nutritive phagocytes, as revealed by histological analyses. Primary oocytes were significantly larger in individuals
held at 3 °C than at 12 °C throughout the winter experiment, regardless of food ration; during the summer experiment, primary
oocytes were significantly larger in individuals receiving the high ration, regardless of the temperature at which they were
held. These results suggest that: (1) food availability is the most important factor regulating energy storage and the relative
size of gonads throughout the year, (2) temperature affects the rate of growth and maturation of primary oocytes during the
later stages of oogenesis, and (3) once gametogenesis has been initiated, mature ova will be produced, even under conditions
of low food availability. Conditions of high food availability in summer and low temperature in winter would thus favor reproductive
output in sea urchin populations.
Received: 1 March 2000 / Accepted: 4 October 2000 相似文献
13.
A mass synchronous spawning of the sea urchin Evechinus chloroticus (Valenciennes) was observed in situ in Doubtful Sound, a large New Zealand fiord. Spawning occurred between 17:30 hrs and
18:30 hrs on 27 January 1994 and coincided with a full moon, spring tides and a period of decreasing sea temperatures. During
spawning, the sea urchins formed a dense spawning aggregation of both sexes, with >90% of the urchins observed spawning at
the time. Spawned gametes clouded the water column, and some were eaten by small labrid fish species. The spawning, which
may have been as widespread as 40 km, marked a 42 to 50% decrease in gonad indices and resulted in a widespread, dense cohort
of E. chloroticus larvae within the fiord.
Received: 25 September 1997 / Accepted: 6 March 1998 相似文献
14.
Sexual reproduction of the reef-building coral Montastreacavernosa was studied in the Santa Marta area, Caribbean coast of Colombia, from October 1990 to October 1991. The area is subjected
to a seasonal upwelling–outwelling regime. From microscopical analysis of tissue sections sampled each lunar month around
the full moon, it was confirmed that this is a gonochoric, broadcasting species, with a single gametogenic cycle per year,
and a 1:1 sex ratio. Oogenesis began a few weeks after spawning, and extended for 11 mo. The onset of spermatogenesis occurred
just before the full moon of June, later than at other localities where sea-water temperatures during the first half of the
year are not as low. The amount of reproductive tissue strongly increased in both sexes after July, in association with an
increase in sea-water temperature and a decrease in photoperiod. The gonad index of fully mature female colonies was about
four times lower than at other localities, perhaps due to the stressful seasonal regime. The male gonad index was lower than
that of the female, indicating sex-related differences in the rates of biomass allocation to reproduction. As in other Caribbean
localities, spawning occurred after the full moons of August and September. However, there was some evidence of a third spawning
episode after the full moon of October, possibly associated with a delay in the occurrence of maximum sea-water temperatures
in near-equatorial localities compared to higher latitudes. The probability of cross-fertilization in this species with a
gonochoric breeding system and a broadcasting mode of reproduction is favored by its balanced sex ratio, its usually high
within-reef zone abundance, and by localized and repeated spawning episodes, synchronized by lunar phase.
Received: 19 April 1996 / Accepted: 24 September 1996 相似文献
15.
Reproduction of Asterina stellifera was studied in two populations from the Cabo Frio region, southeastern Brazil. One was located in an intertidal seagrass
flat at Japonês Island (1994–1995); the second was on a sublittoral rocky shore at Pontal beaches (1999–2000). Reproductive
cycle was studied at monthly intervals by organ indices and histological examinations of gonads. Although these two populations
were studied in different habitats and at different times, the periodicity of the annual reproductive cycle was very similar
for the two populations. The highest gonad index (GI) values were found in August/September (late winter), followed by a drop
in GI values, indicating spawning. The GI and pyloric caeca index (PCI) tended to have an inverse relationship in both populations,
but it was only statistically significant in the rocky-shore population. Gametogenesis in the two populations was described
and roughly confirmed the reproductive cycles determined by GIs.
Published online: 9 August 2002 相似文献
16.
The annual reproductive cycle of the holothurian Aslia lefevrei (Dendrochirota: Echinodermata) 总被引:2,自引:0,他引:2
J. Costelloe 《Marine Biology》1985,88(2):155-165
The dendrochirote holothurian Aslia lefevrei (Barrois) is locally and densely aggregated (>70 individuals m-2) in Galway Bay, on the west coast of Ireland. It has a discrete, relatively short breeding period from the end of February to the beginning of April, with peak activity in March. The sexes are separate and the single gonad, consisting of numerous tubules (100 to 800), lies in the anterior coelom. Both gonad index values and histological observations indicate that gametogenesis resumes in June/July after a brief post-spawned resting period. Little oocyte growth and sperm production occurs over the warm summer months when the holothurian is actively feeding. Gonad index values, however, increase rapidly during this period and reach high values by early winter without concomitant increases in maturity indices. This is subsequently followed by slight reductions in the gonad indices, before reaching peak values in February. It is suggested that this is probably due to the initial build-up and subsequent assimilation of storage products in the gonad, the development of gametogenic products and the frequent assimilation thereafter of unwanted ova. Spawning generally takes between 5 and 60 min, with the entire contents of the gonad rarely being shed in a single release. During this process, the holothurian raises its anterior end and, with the extended tentacles close together, emits a stream of gametes from the genital pore in the mid-dorsal line. Laboratory experiments and general observations indicate that increased temperature and low light levels may influence spawning behaviour.Contribution No. 248 to the School of Marine Sciences, University College Galway, Ireland 相似文献
17.
The reproductive biology of the alfonsino Beryx splendens was studied by histological examinations, gonadosomatic index and macroscopic scales of maturation of a large sample of gonads.
Alfonsino is a gonochoric species. The size-frequency distribution of the sex ratio was bimodal and considered to be due to
size dimorphism. In New Caledonia, the breeding period of this species occurs during the southern summer, with a peak in December
to January. The spawning stage is attained at a minimum fork length of 28 cm for females and 33 cm for males. The size at
which 50% of the population attain sexual maturity (FL50) is 33.2 cm for females and 34.5 cm for males. Maximum potential fecundity is estimated to lie between 270 000 to 675 000
eggs for fish between 34 and 40 cm in fork length. It was possible to differentiate vegetative zones, in which juvenile alfonsino
grow until they reach maturity, from reproductive zones (fishing grounds) which are inhabited by mature individuals. The larvae
and juveniles could be carried from the reproductive zone to the vegetative zone by currents in an oceanic eddy system.
Received: 26 April 1996 / Accepted: 20 September 1996 相似文献
18.
The spawning patterns of two penaeid prawns, Metapenaeus endeavouri (Schmitt) and M. ensis (De Haan), were examined from data collected at 45 stations between March 1986 and March 1992. An index of population fecundity
based on the abundance, proportion and fecundity of sexually mature females was used as a measure of spawning output of the
prawn stock. The population fecundity index for M. ensis was higher than that for M. endeavouri. The monthly population fecundity index for M. endeavouri varied markedly among years, while that for M. ensis was consistent among years. Spawning of M. endeavouri occurred year-round, while that of M. ensis was concentrated mainly in spring (September to November). For M. endeavouri, a minor spawning, derived from a relatively small number of summer spawners, occurred in the 20 to 30 m offshore waters
in summer. In early summer (after May), the major spawning group consisted of large females from the winter-spawning cohort,
and the spawning area shifted to depths of 30 to 60 m. In winter (July), the major spawning, derived from the winter-spawning
cohort, occurred at depths of 20 to 40 m. For M. ensis, the major spawning, derived from the spring-spawning cohort, was observed in depths <50 m and was concentrated particularly
in inshore waters (<20 m) in spring. In autumn, the spawning output was mainly from the autumn-spawning cohort, which comprised
but a small number of individuals. In winter, the major spawning group again consisted of the large females from the spring-spawning
cohort, and spawning increased in the oceanic waters (>50 m). These results suggest that mature female M. endeavouri and M. ensis move offshore (>40 m) by May and July, respectively, and return to shallow waters (<35 m) in July and November, respectively.
The monthly reproduction patterns of both species in the “effective spawning” area showed that the major spawning season for
M. endeavouri is August to October and that for M. ensis is September to December.
Received: 19 February 1999 / Accepted: 18 June 2000 相似文献
19.
Adam D. Hughes Maeve S. Kelly David K. A. Barnes Ana I. Catarino Kenneth D. Black 《Marine Biology》2006,148(4):789-798
Fatty acid analyses are emerging as a powerful technique to probe trophic interactions between organisms. In this paper, the
application of both this procedure and gonad index (GI) determination on two populations (intertidal and subtidal) of the
echinoid Psammechinus miliaris is reported. The investigation spanned the 3-month spawning period of Scottish west coast populations. In both populations
a progressive decrease in the GI was found, coupled with an increasing maturity stage (from mature to spent). Sexual maturation
and decrease in GI was synchronous between the two populations. In conjunction, there were distinct changes in gonad biochemistry.
Differences in the fatty acid composition of the gonad reflected the changes in sexual maturation. Mature males and females
had significant differences in the fatty acid composition of their gonads, whereas post-spawned individuals showed no gender
differences. Male urchins had higher levels of polyunsaturated fatty acids (PUFAs) compared to females, and there was a dramatic
reduction in the fatty acids 22:6(n−3) and 20:5(n−3) with increasing maturity stage. Using multivariate statistical techniques, these changes in the fatty acid composition
of the sea urchin gonad were linked to habitat related diet differences combined with gender differences. These changes in
the fatty acid signatures clearly reflect the dual function of the gonad as both a nutrient store and a reproductive organ. 相似文献
20.
The reproductive biology of Antipathes fiordensis Grange, a species endemic to south-western New Zealand, was followed from April 1994 to May 1995. Ten colonies were individually
tagged in Doubtful Sound and sampled on a monthly basis in order to determine their reproductive activity. The fecundity of
each of the five tagged female colonies was determined by estimating the total number of polyps per colony from photographs
of each colony and by planimetry, the proportion of gravid polyps per colony, and the mean number of oocytes per gravid polyp.
In addition, 56 colonies were sampled in March 1995 to estimate the sex ratio, height at sexual maturity, and mean sizes of
females and males. A. fiordensis was found to be a dioecious species which, in the absence of gonads in the polyps, has no obvious external morphological
differences between the sexes. Broadcast spawning of gametes is the likely mode of reproduction. Gametogenesis began in November
1994 and was highly synchronous within and between colonies, with spawning occurring in March 1995. The sex ratio in adults
was 1:1. Colonies reached sexual maturity between the heights of 70 and 105 cm which, based on existing estimates of growth
rate, corresponds to a minimum age for sexual maturity of about 31 yr. The largest oocytes measured ranged from 100 to 140 μm
in size. Female colonies produced between 1.3 and 16.9 million oocytes, with the larger colonies dominating the reproductive
output of the population.
Received: 23 June 1997 / Accepted: 1 August 1997 相似文献