共查询到20条相似文献,搜索用时 15 毫秒
1.
Douglas P. Middaugh Michael J. Hemmer Yara Lamadrid-Rose 《Environmental Biology of Fishes》1986,15(2):107-117
Synopsis Spawning patterns of inland silversides, Menidia beryllina, and tidewater silversides, Menidia peninsulae, were examined in the laboratory under several combinations of ‘tidal’ and diel light cycle cues. M. beryllina showed a high frequency of spawning throughout the day when held under constant conditions (24L: OD, current velocity 8 cm
sec−1) and when ‘tidal’ and diel light cycles were presented singly or in combination. In contrast, M. peninsulae demonstrated a high frequency of spawning only when presented a combination of ‘tidal’ and diel light cycle cues and spawned
predominantly at night. Menidia beryllina embryos were euryhaline. Hatching ranged from 73 to 78% at salinities of 5,15 and 30‰ M. peninsulae embryos showed an inverse relationship between the percentage hatch and the incubation salinity, 90% at 5‰ and only 65% at
30‰ Survival and growth of larval M. beryllina from the day of hatching through 16 days old was optimal at 15‰ Although survival of M. peninsulae larvae was optimal at 30%, no trend was apparent in growth of larvae held for 16 days at 5, 15 or 30‰ salinity.
Contribution No. 508 from the Gulf Breeze Environmental Research Laboratory 相似文献
2.
Recruitment in Japanese sea bass,Lateolabrax japonicas (Cuvier, 1828): effects of timing on spawning and larval quality and quantity
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This study aimed to elucidate the causes of variability in larval survival and juvenile abundance (recruitment) within and among cohorts of Japanese sea bass (JSB; Lateolabrax japonicus), a winter‐spawning temperate coastal marine fish. Larvae and settled individuals (settlers) belonging to four cohorts were collected from Tango Bay (the Sea of Japan coast) during eight sampling cruises in 2007 and 2008. Larvae were sampled in January and February each year using an ichthyoplankton net, and settlers were collected in February and March each year using a beam trawl. Age of individual larva and settlers was determined and growth history was back‐calculated from otolith microstructure, and the hatch date distribution was computed. Temperature, daily growth rate, size‐at‐age, hatch date, and density data of larvae and settlers allowed elucidating the effects of the timing of spawning and larval quantity and quality (growth rate and body size) on larval survival and recruitment within and among cohorts of JSB. Results showed that cohorts that hatched earlier in the season had higher quantity of larvae, experienced higher mean temperatures and survived better than cohorts hatched later. Recruitment variability among cohorts is determined largely by the initial quantity of larvae, as this explained >97% of the variability in recruitment among cohorts. Within cohorts, larger hatched larvae grew faster than their smaller conspecifics, and the bigger and faster growing larvae survived and settled. Results from this study suggest the following scenarios for recruitment of JSB: (i) earlier spawning in the season promotes larval survival since earlier cohorts are likely to encounter a better temperature and perhaps food conditions, and therefore recruit better than later cohorts; (ii) the initial quantity of larvae appears to be an important determinant of recruitment variability among cohorts; and (iii) the size‐ and growth‐related mechanisms operating during the larval phase appear to start at the time of the hatch. 相似文献
3.
B. Viertel 《Hydrobiologia》1992,234(3):151-173
The influence of particle size, initial particle concentration and larval stage on the ingestion rate, ‘retention efficiency’,
and filtering rate of anuran larvae with varying filter apparatus anatomy and different life histories was investigated for
four species. Larvae of premetamorphic Stages 28 and 32 and prometamorphic Stage 40 were selected for filtering experiments
on the basis of their different growth rates. Three different sizes of silica gel particles were offered as mock food. Particle
concentration was measured photometrically. The Michaelis-Menten model was used to describe the dependency of ingestion rate,
filtering rate, and ‘retention efficiency’ upon initial particle concentration, and to calculate maximum ingestion rate, threshold
concentration, and the half-saturation constant.
(1) The highest ingestion rates, filtering rates and ‘retention efficiencies’ were achieved by Xenopus laevis larvae, followed by Bufo calamita larvae. Bufo bufo larvae lay at the opposite end of the scale. Rana temporaria larvae were placed between B. calamita and B. bufo larvae. This order is attributed to differences in life histories, especially the different breeding environments in which
these larvae occur. (2) The larger the particle size and the older the stage, the greater the tendency toward saturation of
the ingestion rate, filtering rate and ‘retention efficiency’. These filtration parameters are graded according to particle
size. The ingestion rate (number of particles), filtration rate and ‘retention efficiency’ are greatest for PS3. Ingestion
volume is greatest for PS 1. The difference between PS3 and PS2 on the one hand, and PS1 on the other, is often great; for
Stage 28 X. laevis it is very great. This shows that larvae ingest large particles more effectively, and that the most effective ingestion takes
place at Stages 28 and 32, owing to the growth function of these stages. The ability of larvae to ingest large particles effectively
is possibly a very basic phylogenetic characteristic. (3) The threshold concentration is lowest when the particles are at
their largest. In accordance with conclusions drawn by other authors, threshold feeding is attributed to regulation by buccal
pumping and mucus production. Considerable importance is attributed to threshold feeding with respect to larval adaptation
to oligotrophic environments. 相似文献
4.
Reproduction of the lacustrine-riverine form of the Drjagin charr (genus Salvelinus) from Lake Lama (the Noril’sk-Pyasina aquatic system on the Taimyr Peninsula) in a mountain tributary, the Bunisyak River,
as well as the formation and development of skeletal elements in embryos and larvae reared under different experimental conditions
are described. Patterns of the development and the heterochrony between the rates of somatic growth and osteogenesis are an
adaptation to the extremely low water temperature and oligotrophic spawning habitat of the mountain stream. Still, the formation
of vertebral centrae is retarded even at rather high rearing temperatures. As compared to larvae of the small normal (nondwarf)
planktivorous lacustrine form of Arctic charr from Lake Davatchan (Transbaikalia) reared at 3°C, larvae of Drjagin charr from
Lake Lama reared at 1°C are characterized by accelerated growth and heterochronies of osteogenesis. The divergence of the
lacustrine-riverine form of Drjagin charr from the generalized form of Salvelinus alpinus in morphology begins during the larval period of the ontogeny. 相似文献
5.
Guo Zhang Lang Wu Hongtao Li Ming Liu Fei Cheng Brian R. Murphy Songguang Xie 《Environmental Biology of Fishes》2012,93(3):439-447
Commercial catches of the ‘major carps’ (grass carp Ctenopharyngodon idella, silver carp Hypophthalmichthys molitrix, black carp Mylopharyngodon piceus and bighead carp Aristichthys nobilis) in the middle and lower reaches of the Yangtze River have declined precipitously since construction of the Three Gorges
Dam (TGD). To assess specific environmental effects, young-of-the-year major carps were collected below TGD in the Yangtze
River at Jianli (larvae) and E’zhou (juveniles) and in the Dongting Lake (juveniles) during June–August 2007. Lapillar otoliths
were analyzed to determine early growth. There were no discernible growth increments in otoliths for a majority of the larvae
(38 of 63 grass carp and 40 of 47 silver carp), while increments were evident in otoliths formed in the larval stage for all
the juveniles, indicating that larvae without discernible increments failed to recruit to the juvenile stage. Back-calculated
hatch dates of major carps were between 31 May and 24 July. The initiation of the spawning season was delayed about 1 month
compared to pre-TGD records. Larval growth rates, as reflected by otolith-increment width, were lower at Dongting Lake (closer
to TGD) than at E’zhou (farther from TGD), indicating that TGD-moderated effects on early growth and development of carps
are more apparent for fishes hatched nearer to the dam. The delay in spawning and decreased early growth may partly explain
the recent decline of the major carp resources in the middle and lower Yangtze River. 相似文献
6.
Microcuttings of three strains of ‘McIntosh’ apple that varied in their growth habit under field conditions were tested for
their tolerance to three cytokinins (BA, kinetin, and 2iP) and one cytokinin-like compound (TDZ) in vitro. The three strains
were ‘McIntosh’ (standard), ‘Macspur’ (intermediate) and ‘Wijcik’ (dwarf). For each cytokinin ‘Wijcik’ was more tolerant of
high cytokinin levels than either ‘Macspur‘, which showed an intermediate tolerance, or ‘McIntosh’ which did not tolerate
(died) high levels of cytokinins. These results show that ‘Wijcik’ exhibits multiple cytokinin tolerance in vitro. The relationship
between growth habit and BA tolerance has been reported earlier. The present study demonstrates that cytokinins can be used
to differentiate among growth types in apple.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
Sergey S. Alekseyev Mikhail V. Mina Ella M. Smirina Aleksey A. Sokolov 《Environmental Biology of Fishes》2009,86(4):487-505
In some polymorphic populations of Arctic charr in Transbaikalia, an individual can transform from a smaller to larger size
form during their lifetime as a result of accelerated growth that follows a period of slow growth and reproduction as a small
size form. Alternating periods of slow and fast growth are reflected in growth layer patterns visible in fin ray cross sections.
Stained microtome fin ray cross sections were used to reveal the incidence of transformations from one form to another. Data
were collected from 14 northern Transbaikalian lakes containing two or three sympatric Arctic charr forms (‘dwarf’, ‘small’,
and ‘large’) exhibiting varying levels of morphological separation. Individuals recruited from the dwarf or small form were
found in varying proportions among the small and/or large form in 12 lakes. Small or large form charr that grew without noticeable
acceleration to the adult size typical of the form or experienced accelerated growth as juveniles prior to maturation were
also observed. There were no transformations between sympatric forms that differed in the length and number of gill rakers
and in some other meristic characters. Results indicate that in the region under study, transformations of sympatric Arctic
charr size forms are a widespread, but not a ubiquitous, phenomenon. Such transformations reflect the plasticity of the developmental
channels of the forms. In the course of intra-lacustrine form divergence and genetic differentiation, the frequency of the
observed transformations decreases to zero. 相似文献
8.
Allen Keast 《Environmental Biology of Fishes》1985,12(2):119-129
Synopsis Analysis of the piscivore guild in fish species-rich lake and stream systems in eastern Ontario showed the co-occurrence of
three types: (1) specialists that became piscivorous at the age of a few weeks (Esox, Micropterus); (2) ‘secondary’ piscivores that are fish-eaters only later in life (Perca, Ambloplites); and (3) species in which fish consumption is limited to taking some larvae (Lepomis macrochirus). In the first group the basic series of dietary shifts that characterize many long-lived fish (i.e. zooplankton followed
by small invertebrates then large invertebrates and finally fish); is greatly accelerated. Prey size increases with growth.
Overall prey selection was on the basis of body size and abundance. Most piscivores took a range of fish prey. There was little
evidence of specialization at the species level. Esox and Micropterus spawn some weeks ahead of their major prey species. This is seen as adaptive. Their young harvest the larvae of the latter.
The ensuing predator/prey association with growth is highly advantageous to the piscivore as prey of optimum body size are
thus continually available. 相似文献
9.
Paul A. Hohenlohe 《Invertebrate Biology》2002,121(1):25-37
Abstract. The intertidal, sibling species Littorina scutulata and L. plena (Gastropoda, Proso‐branchia) are sympatric throughout most of their ranges along the Pacific coast of North America. Both species release disc‐shaped, planktonic egg capsules from which planktotrophic veliger larvae hatch. Here I review existing data and present new observations on these species' life history, including age at first reproduction, spawning season, maximum fecundity rates, capsule morphology, egg size and number, pre‐hatching development, larval growth at three food concentrations, potential settlement cues, planktonic period, and protoconch size. Previous classification of egg capsule morphologies used to distinguish the species is inaccurate; instead, capsules can be categorized into three types of which each species may produce two. Females of L. scutulata produced capsules with either two rims of unequal diameter or one rim, while females of L. plena produced capsules with one rim or two rims of nearly equal diameter. Females of each species spawned sporadically from early spring to early fall in Puget Sound. Larvae of L. plena hatched one day earlier than those of L. scutulata, and both species grew fastest in the laboratory at intermediate food concentrations. Larvae metamorphosed in the presence of a variety of materials collected from their adult habitat, including conspecific adults, algae, rocks, and barnacle tests. This is the first report of planktotrophic larvae in this genus metamorphosing in the laboratory. The total planktonic period of 8 larvae of L. scutulata raised in the laboratory was 37–70 days, and a single larva of L. plena metamorphosed after 62 days. Protoconch diameter of shells collected from the field was 256–436 μm and did not differ significantly between the species. Previous allozyme and mitochondrial DNA work has suggested high levels of genetic variability in both species and greater genetic population structure in L. plena, despite the long spawning season and long‐lived larvae in both species. The interspecific life history differences described here appear insufficient to produce consistent differences in gene flow patterns. 相似文献
10.
The present paper reviews the effects of water temperature and flow on migrations, embryonic development, hatching, emergence, growth and life‐history traits in light of the ongoing climate change with emphasis on anadromous Atlantic salmon Salmo salar and brown trout Salmo trutta. The expected climate change in the Atlantic is for milder and wetter winters, with more precipitation falling as rain and less as snow, decrease in ice‐covered periods and frequent periods with extreme weather. Overall, thermal limits for salmonids are species specific. Scope for activity and growth and optimal temperature for growth increase with temperature to an optimal point before constrain by the oxygen content of the water. The optimal temperature for growth decreases with increasing fish size and varies little among populations within species, whereas the growth efficiency may be locally adapted to the temperature conditions of the home stream during the growth season. Indirectly, temperature influences age and size at smolting through its effect on growth. Time of spawning, egg hatching and emergence of the larvae vary with temperature and selective effects on time of first feeding. Traits such as age at first maturity, longevity and fecundity decrease with increasing temperature whilst egg size increases with temperature. Water flow influences the accessibility of rivers for returning adults and speed of both upstream and downstream migration. Extremes in water flow and temperature can decrease recruitment and survival. There is reason to expect a northward movement of the thermal niche of anadromous salmonids with decreased production and population extinction in the southern part of the distribution areas, migrations earlier in the season, later spawning, younger age at smolting and sexual maturity and increased disease susceptibility and mortality. Future research challenges are summarized at the end of the paper. 相似文献
11.
J. Sivinski 《BioControl》1991,36(3):447-454
Among the host fruits of the Caribbean fruit fly there are a variety of sizes and shapes. These morphological differences
may influence the vulnerability of the larvae to parasites. In the laboratory, Caribbean fruit fly larvae placed in the smaller
of 2 different sizes of artificial ‘fruit’ (cloth spheres filled with a diet material) were parasitized at a higher rate by
the braconid,Diachasmimorpha longicaudata (Ashmead) when spheres were presented separately. However, when parasites were simultaneously presented with 6 different
sizes of ‘fruit’ there was no significant relationship between size and parasitization rate. This may be due to the parasites
preference to search for larvae in larger ‘fruit’. In field collections of different species of host fruit, a significant
inverse correlation exists between fruit radius and rate of parasitization. However, host fruit size accounts for only about
5% of the variance in yearly parasitization rates.
相似文献
12.
Gudo M 《Acta biotheoretica》2005,53(3):191-216
The early evolutionary history of echinoderms was reconstructed on the basis of structural-functional considerations and application
of the quasi-engineering approach of ‘Konstruktions-Morphologie’. According to the presented evolutionary scenario, a bilaterally symmetrical ancestor, such as an enteropneust-like organism,
became gradually modified into a pentaradial echinoderm by passing through an intermediate pterobranch-like stage. The arms
of a pentaradial echinoderm are identified as hydraulic outgrowths from the central coelomic cavity of the bilateral ancestor
which developed due to a shortening of the body in length but widening in the diameter. The resulting pentaradial symmetry
is a consequence of mechanical laws that dictate minimal contact surface areas among hydraulic pneumatic entities. These developed
in the coelomic cavity (metacoel) in the bilaterally symmetrical ancestor, when from the already U-shaped mesentery with the
intestinal tract two additional U-shaped bows developed directly or subsequently. During the subsequent development tensile
chords of the mesentery ‘sewed’ the gut with the body wall first in three and secondly in five ‘seams’. During the direct
development five ‘seams’ between tensile chords and body wall developed straightly. These internal tensile chords subdivide
the body coelom into five hydraulic subsystems (‘pneus’), which eventually arrange in a pentaradial pattern. The body could
then enlarge only between the tensile chords, which means that five hydraulic bulges developed. These bulges initially supported
the tentacles and finally each of them enclosed the tentacle until only the feather-like appendages of the tentacles projected
over the surface. The tentacles with their feathers were transformedinto the ambulacral system, and the bulges become the
arms. These morphological transformations were accompanied and partly determined by specific histological modifications, such
as the development of mutable connective tissues and skeletal elements that fused to ossicles and provided shape stabilization
in form of a calcareous skeleton in the body wall. The organism resulted was an ancestral echinoderm (‘Ur-Echinoderm’) with an enlarged metacoel, stabilized by hydraulic pressure working againsta capsule of mutable connective tissue, skeletal
elements and longitudinal muscles. In regard to these reconstructions, the body structure of echinoderms can be understood
as a hydraulic skeletal capsule. 相似文献
13.
The spionid polychaete speciesPolydora ligni, P. ciliata, andPygospio elegans were cultivated in the laboratory over several successive generations. A flow-through cultivation system forPolydora spp. is described. Duration of life cycles (time from hatching of the larva to first reproduction) and life spans (hatching to death) of these species were not significantly influenced by the degree of inbreeding nor by individual age of the parents. Minimum time from metamorphosis (15-setiger stage) to first hatching of offspring larvae (in the 3-setiger stage) at 18°C was 33 days inPolydora spp. and 81 days inPygospio elegans. Larval growth patterns are described in terms of number of setigers, body length, and biomass (dry weight, carbon, nitrogen, hydrogen), in relation to time after hatching. Regression models are proposed which link these measures of larval growth and, thus, may be used for conversions. Rates of development and growth show a high degree of variability in all three species, not only caused by variation in environmental factors such as temperature or food, but also among and within single hatches of larvae reared under identical conditions. Larvae were reared at constant temperatures (6°, 12°, and 18°C). Temperature affected larval growth inPolydora ligni more than inP. ciliata, and least of all inPygospio elegans. Only the latter species was able to develop at 6°C from hatching to metamorphosis. This differential response may be explained by differences in the natural spawning season of these species. Eleven phytoplankton species were tested as to their food values. A relative index of growth is proposed which compares the slopes of two growth curves (one standard and one test condition). The flagellateDunaliella tertiolecta was used as a standard food in these experiments. Most algal species were less suitable, and only the diatomThalassiosira rotula was consistently better food for spionid larvae thanD. tertiolecta. 相似文献
14.
Yo Morimoto Jun-ya Shibata Mizuki Takahata Omar Myint Masanori Kohda 《Journal of Ethology》2010,28(3):429-436
Like many other gobies, male Isaza (Gymnogobius isaza) which are endemic to Lake Biwa, Japan, exclusively care for broods in nests. This goby may have an optimal range of brood
size (i.e., an average clutch size of about 2000–3000 eggs) within which they may produce larger numbers of hatching young
because much larger broods may be destroyed by fungal infection before hatching. This optimal brood size hypothesis (Takahashi
et al. in J Ethol 22:153–159, 2004) predicts that (1) after spawning, both males and females will refuse additional spawning by other gravid females (second
females) to keep brood sizes within optimal ranges, (2) larger fish will repel second females more successfully than will
smaller fish, and thus, (3) both sexes prefer larger mates. To examine these predictions, we first observed Isaza’s aggressive
behaviors in aquaria and investigated whether fish attacked and repelled second females that were introduced after spawning,
and, if so, what were the sizes of fish that did so. Large fish, regardless of sex, aggressively prevented second females
from entering the nest, but second females larger than the pairs displaced the pair females forcibly and spawned eggs into
their clutches. Mate choice experiments showed that males preferred large females. Although females’ choice of large mates
was not confirmed, many results may largely coincide with the predictions of the optimal brood size hypothesis. Thus, Isaza
males’ choice of large mates will be advantageous for defending against brood parasitism by conspecific females and for achieving
optimal clutch size. 相似文献
15.
The potential impacts of climate change on inshore squid: biology, ecology and fisheries 总被引:2,自引:0,他引:2
Squid are important components of many marine ecosystems from the poles to the equator, serving as both important predators
and prey. Novel aspects of their growth and reproduction mean that they are likely to play an important role in the changing
oceans due to climate change. Virtually every facet of squid life-history examined thus far has revealed an incredible capacity
in this group for life-history plasticity. The extremely fast growth rates of individuals and rapid rates of turnover at the
population level mean that squid can respond quickly to environmental or ecosystem change. Their ‘life-in-the-fast-lane’ life-style
allows them to rapidly exploit ‘vacuums’ created in the ecosystem when predators or competitors are removed. In this way,
they function as ‘weeds of the sea’. Elevated temperatures accelerate the life-histories of squid, increasing their growth
rates and shortening their life-spans. At first glance, it would be logical to suggest that rising water temperatures associated
with climate change (if food supply remains adequate) would be beneficial to inshore squid populations and fisheries—growth
rates would increase, life spans would shorten and population turnover would accelerate. However, the response of inshore
squid populations to climate change is likely to be extremely complex. The size of hatchlings emerging from the eggs becomes
smaller as temperatures increase and hatchling size may have a critical influence on the size-at-age that may be achieved
as adults and subsequently, population structure. The influence of higher temperatures on the egg and adult stages may thus
be opposing forces on the life-history. The process of climate change will likely result in squids that hatch out smaller and earlier,
undergo faster growth over shorter life-spans and mature younger and at a smaller size. Individual squid will require more
food per unit body size, require more oxygen for faster metabolisms and have a reduced capacity to cope without food. It is
therefore likely that biological, physiological and behavioural changes in squid due to climate change will have far reaching
effects. 相似文献
16.
Previous studies have suggested that there is a strong relationship between a high degree of aggressive competition among
males for access to fertile females and large body and canine size in males. It has further been suggested that such a relationship
among living primates can be used to infer the social organization of extinct primate species from the degree of sexual dimorphism
exhibited.
Our field studies of patas (Erythrocebus patas) and blue monkeys (Cercopithecus mitis), two species which had previously been characterized as having one-male ‘harem’ group structures, indicate considerable
variability in mating systems. We suggest, on the basis of our observations of these species, that factors other than male-male
competition (e.g., predation) may also have influenced the degree of dimorphism in primates. 相似文献
17.
The significance of sound interception to males of the bicolor damselfish,Pomacentrus partitus,during courtship 总被引:1,自引:0,他引:1
Todd N. Kenyon 《Environmental Biology of Fishes》1994,40(4):391-405
Synopsis Playback experiments conducted in the field and the laboratory demonstrated the use of sound interception in bicolor damselfish,Pomacentrus partitus. Two courtship sounds produced by male bicolors: the ‘chirp’ which occurs at the initiation of courting and the ‘grunt’ which
occurs near the termination, just prior to spawning, were found to hold different meanings to intercepting male competitors.
Males responded to grunt playback with directional swimming towards the sound source and increased courtship behavior. No
directional response was observed during chirp playback. The grunt sound appears to indicate that a spawn-ready female is
present near the sound source. Males therefore move towards it, likely to interfere with the imminent spawning or to gain
a possible spawning partner. Such is not observed in response to chirps, as little advantage would be gained by moving to
the source of a sound which is known to serve as an ‘advertisement’ or ‘territorial keep-out’ signal. Thus, upon intercepting
a neighbor's chirps, males exhibit courting within their own territory, or directly court a nearby female. 相似文献
18.
Despite many ecological studies the population morphological variability within the freshwater crustacean genus Daphnia is poorly investigated, especially during postembryonic development. Unusual phenotypic plasticity of some Daphnia species results in tremendous difficulties in morphological species delineation. The ontogenetic morphological variation
of this species was studied, revealing the general trends in body shape variation in different populations. The morphotypes
of size and age groups of D. galeata turned out to be more variable at the mouth of the Kargat River (Lake Chany basin) than in Lake Todzha (Bol’ shoi Yenisei
River basin); however, the growth of characters such as the helmet and tail spine was described by an allometric function
and their absolute sizes decreased with age in Daphnia from both water basins. It is shown that the first mature size-and-age group of D. galeata is most suitable for investigating population morphological variation. 相似文献
19.
J. G. Wakibia J. J. Bolton D. W. Keats L. M. Raitt 《Journal of applied phycology》2006,18(3-5):565-573
As a possible means of improving the livelihoods of local villagers, off-bottom rope cultivation of commercial eucheumoids was investigated on the southern Kenyan coast at three sites, representative of the variety of environments. The morphotypes used were brown Eucheuma denticulatum and green and brown Kappaphycus alvarezii. The study was carried out over a 15 month period from August 2001 until October 2002. Relative growth rates were highest at a sandy flat in a mangrove system (Gazi; 5.6% d−1), and lowest in an intertidal reef flat (Kibuyuni; 3.2% d−1) with a lagoon being intermediate (Mkwiro; 4.8% d−1). The brown E. denticulatum had the highest growth rate of 4.7% d−1 compared to the green and brown K. alvarezii which were 4.3% d−1 and 4.2% d−1, respectively. Growth was more variable at Kibuyuni and Mkwiro. The growth was higher during the southeast monsoon (4.7% d−1) than during the northeast monsoon (4.0% d−1). This is part of a larger study and the effects of water motion, salinity, temperature, thallus nitrogen, and ‘ice-ice’ syndrome on growth of morphotypes is discussed. The water motion was observed to increase thallus nitrogen and hence the growth of eucheumoids. The ‘ice-ice’ condition affected both brown E. denticulatum and brown K. alvarezii but not green K. alvarezii. The results suggest that commercial cultivation of eucheumoids in Kenya will be feasible. 相似文献
20.
Tetsuo Kuwamura Yutaka Yogo Yasuhiro Nakashima 《Ethology : formerly Zeitschrift fur Tierpsychologie》1993,95(1):65-75
Paragobiodon echinocephalus (Pisces; Gobiidae) inhabits the branching coral Stylophora pistillata. Only the largest two fish bred in a coral irrespective of group size, which was larger in larger corals. Breeding pairs consisted of a male and female of similar body size. Eggs were spawned on the coral branch and guarded by the male parent for about 4 days until hatching. Successive spawning occurred usually one day after hatching. The reproductive success of a pair, measured as the number of newly hatched larvae, was positively correlated with the body size of the male as well as the female. That is, not only female fecundity but also male ability of egg guarding were limited by body size almost equally. This should promote size-assortative monogamy in the goby. 相似文献