摘要:

Although a tendency for high latitude marine invertebrates to avoid pelagic larval stages was first described in the 19th century, the most detailed early study was that of Thorson in Greenland. This work also established other features of the reproduction of polar marine invertebrates that have become regarded as almost axiomatic (e.g., the release of larvae to coincide with the summer bloom) or largely ignored (a latitudinal cline in egg size within species). This short and selective review examines Thorson's conclusions in the light of recent work. It is now clear that although polar prosobranch gastropods reproduce almost entirely by direct development, for many taxa the real distinction between polar and non-polar species is in the proportion of feeding to non-feeding larvae. Some species release feeding larvae in winter and the energy source for these larvae is obscure. Growth is slow and there is little or no evidence for temperature compensation. Many crustacean species have larger eggs at higher latitudes. Egg size varies significantly within species, with larger eggs being associated with larger females and often reduced fecundity. The reasons for these within-species patterns are currently unresolved.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672270

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Studies over the last 15 years have revealed that deep-sea benthic megainvertebrates show a variety of reproductive patterns that are adapted to the deep-sea, an environment in which the fauna occurs at low densities and resources are sparse. In the NE Atlantic the majority of species reproduce year round whilst a limited number of species reproduce on a seasonal basis believed to be entrained by the deposition of surface derived organic material on the deep-sea bed. A third pattern of rapid growth and early reproduction is found in a limited number of species that utilize unpredictable and ephemeral resources in the deep sea. Examination of the fertilization and behavioural biology of species from the bathyal depths suggest some species enhance fertilization success by forming pairs during their breeding season. However, the same concentration of sperm, as seen in shallow water invertebrates, is required for successful fertilization. At least one deep-sea species of echinoid requires high pressure for successful embryogenesis suggesting a depth-related segregation of deep-sea fauna. The origin of megafaunal populations of deep-sea invertebrates in the N. Atlantic is discussed in the light of these new data in relation to varying reproductive patterns and the environmental changes that have occurred during the last deglaciation.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672271

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Study of latitudinal variation in seasonality of reproduction and recruitment of benthic marine invertebrates is useful in generating and testing hypotheses about causal factors acting on reproduction such as temperature and larval food supply that might be altered by changes in world climate. Analysis of latitudinal variation in reproductive patterns might be made with comparisons (a) among species with a common phylogenetic history from different latitudes and habitats and (b) among phylogenetically different taxa from the same location. Hypotheses on variation of reproductive seasonality with latitude are tested here with results of a study on nine species of caridean and two species of sicyoniid shrimp sampled from a tropical seagrass meadow in Puerto Rico. Breeding condition was determined by the presence or absence of incubated embryos (carideans) and the state of ovarian development in both carideans and sicyoniids. Recruitment was estimated from the percentage of individuals of monthly population samples in the juvenile size classes. Comparison of reproductive patterns among tropical, subtropical, and cool temperateSicyoniaspp. supports the paradigm of continuous reproduction in the tropics with increased restriction of breeding season with an increase in latitude. A greater intensity of breeding effort appears to accompany the shorter breeding period associated with an increase in latitude. At the tropical site most females of all caridean species carried embryos during all months of the year. With the onset of sexual maturity, caridean females produced consecutive broods for the rest of their relatively short (< 6 month) life span. In both sicyoniid and caridean species, recruitment occurred throughout the year but was highly variable, i.e., episodic rather than truly continuous or seasonal. Patterns of recruitment were highly concordant among but not between sicyoniid and caridean species, indicating that different sets of environmental factors controlled recruitment in the two groups. It is suggested that simultaneous study of adult reproduction and larval ecology is necessary to understand patterns of reproduction and recruitment. Coordinated effort on a global scale in studying latitudinal variation in reproduction and recruitment is suggested in order to predict the consequences of climate change on commercially and ecologically important marine invertebrate species.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672272

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Seasonal reproduction in Crustacea is synchronized by environmental cues (e.g., temperature and photoperiod). Two types of responses occur: (1) in reptant decapods, short photoperiods and low temperatures are necessary to induce vitellogenesis; (2) in natant decapods and in most peracarids, both high temperatures and long photoperiods promote the onset of reproduction. In this context studies on the biological clocks involved in photoperiodic time measurement were performed on two crustaceans: the ditch shrimpPalaemonetes variansand the woodlouseArmadillidium vulgare, which is distributed worldwide outside polar and intertropical areas. The most important feature of the photoperiodic response curves was the same mean lag time in response to photophase length ≤ 12 h: short photophases delayed breeding but did not prevent it (i.e., “short-day effect”). On the contrary, long photophases promoted the onset of reproduction (i.e., “long-day effect”) differently inP. variansandA. vulgare. In A. vulgarestrains the shape of the photoperiodic response curve depended on latitudinal origin. Results of “resonance” experiments provided evidence of involvement of an endogenous circadian component in the photoperiodic clocks of the two species according to the internal coincidence model developed for insects. Seeing that relations between reproduction and moulting were different in the two species, we proposed the hypothesis of an evolutionary change in the transition from the sea to the continental environment.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672273

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We describe the spawning behaviour and some aspects of spawning periodicity in a diverse group of marine invertebrates, principally echinoderms, but including sponges, anthozoans, molluscs, and polychaetes. Our observations were made both opportunistically and on a systematic basis between 1978 and 1992 on the central and northern Great Barrier Reef. Spawning was predictable in some of the species observed, for exampleBohadschia argus, Euapta godeffroyi, andStichopus variegatus(Holothuroidea), which exhibited regular lunar and diel periodicity. Others, such asHolothuria coluber, Actinopyga lecanora, andBohadschia graffei(Holothuroidea),Acanthaster planei(Asteroidea),Hyotissa hyotisandArcaspp. (Bivalvia) exhibited no clear lunar or diel periodicity in spawning behaviour. Mass heterospecific spawnings which involved several species, often from different phyla, were commonly observed. The species participating were usually those with unpredictable spawning patterns and while the species involved were diverse there were also occasions when spawning involved species from the same genera. Fertilization rates were measuredin situfor the predictable spawnerBohadschia argusand were found to vary between 0–96% depending on the circumstances of the spawnings. Fertilization rates for the unpredictable spawners showed similar variability;Holothuria coluberandActinopyga lecanoraranged from 9–83%.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672274

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Spawnings, larval occurrence and settlement of some marine invertebrates were examined over a six-year period at Lough Hyne, an inlet on the south coast of Ireland. Sea temperature rises were associated with multi-phyla spawnings, temperatures varied between years and greater numbers of larvae and greater settlements were noted in the warmer years. It is suggested that, should sea temperatures rise, conditions for successful recruitment for some species will become more favourable in Irish waters. However, unpredictable effects such as the expansion of exotic populations because conditions become more favourable for them may result in significant modification of diversity and abundance of species.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672275

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The variability of the mild Irish climate is described. The effect of a slight rise in temperature is discussed as far as aquatic organisms are concerned. The effect is likely to be most marked on pelagic populations of marine organisms such as squid and also on intertidal animals. A rise in mean sea level is an indirect result of global warming, and this is likely to have an effect on estuarine organisms and mud flat dwellers. It is suggested that those organisms which are close to the southern limits of their distribution in Ireland may disappear from our fauna. Examples are given from earlier periods and from the present-day fauna. There is likely to be an expansion of the distribution of southern forms which at the moment are near the northern limit of their range. As far as terrestrial animals are concerned, the problem of whether the rainfall pattern will also change is discussed. The likely effects of this on parasite and free-living populations (including the fauna of temporary water bodies, common in West Ireland) are discussed. The complications introduced by diapause and related factors are considered. The fauna of peat bogs may be seriously affected and also those organisms dependent on certain food plants. The peculiar problems of Ireland in having so many empty niches is considered in relation to the increased dangers of accidental introductions.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672276

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The efficient culture of an animal requires a reliable year-round supply of seed. However, in most species knowledge is insufficient for the degree of broodstock control required to schedule seed production throughout the year. Although it has been relatively easy to identify the regulatory parameters in some species, in many others it has been difficult. In the American lobster (Homarus americanus), controlling mechanisms are complex: responses to temperature and photoperiod vary with environmental history and season, and shifting the onset of a temperature increase by only a few days can produce entirely different responses. After two decades of experimental work, we have finally developed a broodstock system that produces synchronous and predictable spawning as required. Two strategies are used to produce year-round seed from a stock that normally spawns in July: (1) photophases (LD 8:16); and (2) spawning is achieved through the late summer and autumn (August-December) by delaying spawning with low temperatures (1–2°C).

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672277

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Astacid crayfishes, native to western Eurasia and western North America, are iteroparous and long-lived (6–12 years), reaching final sizes of about 30–500 g and 90–200 mm total length, depending on species. While economically valuable, their low fecundity and slow growth makes economic aquaculture difficult. In Spain and Ireland the relatively small native white-clawed crayfishAustropotamobius pallipes(Lereboullet) carries around 70 eggs for 8–9 months and reaches first maturity at 3–4 years and 50 mm total length. The larger signal crayfishPacifastacus leniusculusDana, introduced to Europe from California, matures at about 70 mm and 2 years and carries some 200 eggs for 8 months.A. pallipesalone occurs in Ireland; both species in Spain. We have investigated fecundity, oviposition and subsequent egg development of diese species in field and laboratory and developed strategies to maximize egg survival in artificial incubators. Temperature manipulations may be used to maximize juvenile survival and also to modify incubation period. For successful aquaculture critical phases in captivity are mating and fertilization, pleopodal egg attachment, late embryo survival and moult from Stage 1 hatchlings to free-living Stage 2 juveniles.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672278

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The current state of knowledge relating to the reproduction of the commercially important open thelycum shrimps (Crustacea: Penaeidae) is reviewed with particular reference toPenaeus vannamei.Industry standard procedures for the breeding of shrimps in captivity are reviewed against a background of knowledge concerning the maturation processes in males and females. The factors controlling maturation are not completely understood, and it is not clear whether maturation of females is size-or age-dependent. Although unilateral eyestalk ablation is routinely used to induce maturation, the physiological mechanism of this operation is not properly understood. Further research on environmental conditions for successful maturation is required. Nutrition is an important component in successful artificial breeding programs that still rely on the provision of natural foods (squid and polychaeta). The processes of oocyte formation, mating, spawning and hatching are discussed in relation to observations made at the Gulf Coast Research Laboratory.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672279

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor