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1.
Late larvae of the serranid coral trout Plectropomus leopardus (Lacepède), captured in light traps, were released during the day both in open water and adjacent to two reefs, and their
behaviour was observed by divers at Lizard Island, northern Great Barrier Reef. Coral trout larvae (n = 110) were present in light-trap catches from 18 November to 3 December 1997, including new moon (30 November). The swimming
speed of larvae in open water or when swimming away from reefs was significantly greater (mean 17.9 cm s−1) than the speed of larvae swimming towards or over reefs (mean 7.2 cm s−1). Near reefs, larvae swam at average depths of 2.7 to 4.2 m, avoiding 0 to 2 m. In open water, swimming depth varied with
location: larvae >1 km east of Lizard Island swam steeply downward to >20 m in 2 to 4 min; larvae >1 km west oscillated between
2.6 and 13 m; larvae 100 to 200 m east of Lizard Island oscillated between 0.8 and 15 m. Nearly all larvae swam directionally
in open water and near reefs. In open water, the average swimming direction of all larvae was towards the island, and 80%
(4 of 5) swam directionally (p < 0.05, Rayleigh's test). Larvae swam directionally over the reef while looking for settlement sites. The frequency of behaviours
by larvae differed between two reefs of different exposure and morphology. Depending on site, 26 to 32% of larvae released
adjacent to reefs swam to open water: of these, some initially swam towards or over the reef before swimming offshore. In
some cases, offshore-swimming seemed to be due to the presence of predators, but usually no obvious cause was observed. Depending
on the reef, 49 to 64% of the larvae settled. Non-predatory reef residents aggressively approached 19% of settlers. Between
5 and 17% of the larvae were eaten while approaching the reef or attempting to settle, primarily by lizardfishes but also
by wrasses, groupers and snappers. A higher percentage of larvae settled in the second week of our study than in the first.
Average time to settlement was short (138 s ± 33 SE), but some larvae took up to 15 min to settle. Average settlement depth
was 7.5 to 9.9 m, and differed between locations. No settlement took place on reef flats or at depths <4.2 m. Larvae did not
appear to be selective about settlement substrate, but settled most frequently on live and dead hard coral. Late-stage larvae
of coral trout are capable swimmers with considerable control over speed, depth and direction. Habitat selection, avoidance
of predators and settlement seem to rely on vision.
Received: 7 July 1998 / Accepted: 26 January 1999 相似文献
2.
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
3.
Assignment of individuals to populations based upon genetic data is an important ecological problem that requires many polymorphic
markers, often more than are available using single locus techniques. To demonstrate the utility of amplified fragment length
polymorphisms (AFLP) in studying larval dispersal and recruitment in coral populations, two sets of AFLP primers were used
to genotype colonies of the coral Agaricia agaricites Linnaeus from three widely separated geographic locations: the Bahamas (23°28′N, 75°42′W) and Key Largo, Florida (24°55′N,
80°31′W—two sites separated by 12 km) in 1995, and the Flower Garden Banks (FGB) in the Gulf of Mexico (27°55′N,93°36′W) in
1997. In addition to adult samples from each site, recruits were collected from settling plates placed on the East FGB for
1 year (1997–1998). The AFLP technique yielded 45 polymorphic markers. An analysis of molecular variance (AMOVA) showed significant
genetic differences among the four adult populations, even between the two Key Largo sites. The recruits were significantly
different from all adult populations except those from the FGB. Discriminant function analysis and the program AFLPOP were
used to assign individuals to populations. Using the adult AFLP-banding patterns to build the statistical models, both procedures
correctly assigned the majority of adults to their respective populations in simulations and assigned all but one of the recruits
to the Flower Garden population from where they were collected . The AFLP technique provides a simple and adaptable population
assignment method for studying recruitment processes in A. agaricites and other coral species.
Electronic Supplementary Material Supplementary material is available for this article at 相似文献
4.
The current contribution deals with the reproductive biology of a genus endemic to Brazil –Mussismilia Ortmann, 1890 – including all three species of the genus: M. braziliensis (Verrill, 1868), M. hartti (Verrill, 1868), and M. hispida (Verrill, 1902), which occur sympatrically in the studied area, the Abrolhos Reef Complex, Brazil. Sexuality patterns, modes
of reproduction, synchrony and spawning periods are reported, and were determined by histological examination of material.
All three species started to develop female and male gametes over different periods in the same breeding season. The three
species are probably broadcast spawners, since no embryos or planulae were observed in any species at any given time of the
year. Each reproductive cycle lasted approximately 11 months. Oogenesis and spermatogenesis started in different periods,
with spermaries appearing in approximately the eighth month of ovary development and lasting about 3 months. Reproductive
cycles were annual. Spawning probably occurred in consecutive months in each species. In M. braziliensis, spawning presumably happened between March and the middle of May in 1996 and 1997. Evidence suggested that spawning events
of M. hispida took place between the end of April and mid-June. M. hartti may have spawned between September and November. The data presented here suggested that all studied species have at least
one exclusive spawning period, asynchronically with the others. A possible exception may be the simultaneous (or close) spawnings
of M. braziliensis and M. hispida in May. It is suggested that asynchrony in spawning periods among species may reduce the chance of hybridization, gamete
waste and the competition for settlement surfaces. The occurrence of extended spawning periods for each species may also reduce
the risks of reproductive failure, due to temporary adverse conditions.
Received: 8 December 1998 / Accepted: 15 July 1999 相似文献
5.
Temporal succession and spatial segregation of clupeoid larvae in the coastal waters off the Tanshui River Estuary, northern Taiwan 总被引:2,自引:0,他引:2
In the coastal waters off the Tanshui River Estuary in northern Taiwan, eight species of clupeoid larvae were observed. They
exhibited a distinct temporal succession in association with seasonal temperature changing. The time of peak abundance of
Etrumeus teres was in January, Engraulis japonicus in late April, Sardinella spp. in mid-May, Dussumieria elopsoides in early June, Thryssa dussumieri in late June, Stolephorus insularis in mid-September, Encrasicholina heteroloba in early October and E. punctifer in mid-November. The time intervals of the temporal succession of the fishes were approximately 15 to 25 d in the spring/summer
and 25 to 35 d in the autumn/winter fishing seasons. Also, they showed spatial segregation by distributing in areas with different
water depths: Sardinella spp. at a water depth of 10 to 20 m, T. dussumieri at less than 10 m, E. heteroloba at 20 to 50 m and E. punctifer at 10 to 40 m. The larvae of these sympatric clupeoid species segregated their nursing periods and areas apparently to reduce
competition for habitat and thus to maximize the utilization of resources.
Received: 3 March 1997 / Accepted: 19 March 1997 相似文献
6.
Strontium to calcium ratios were observed along longitudinal sections of statoliths of nine neon flying squid, Ommastrephes bartrami (LeSueur, 1821), including three mature females (422 to 454 mm mantle length, ML; 207 to 306 d old) obtained from the North
Pacific (27–35°N; 144–150°E) during winter and six immature males and females (187 to 226 mm ML; 126 to 164 d old) collected
from 39°N; 145°E and 39°N; 169°W during summer. The distances between the nucleus (core) and the edge of the dorsal dome were
approximately 660 to 690 μm in mature females and 450 to 510 μm in the immature squid. Sr/Ca ratios were determined at intervals
of 30 μm between the nucleus and edge of the dorsal dome. Sr/Ca ratios were higher in areas near the nuclei and peripheral
portions of the dorsal dome than in the middle portions of the statoliths (270 to 420 μm from the nuclei, corresponding to
ages of 60 to 90 d) in mature females; thus a U-shaped pattern was evident. Sr/Ca ratios in the six immature squid decreased
from nucleus to the dorsal dome; in three squid the ratios slightly increased toward the dorsal dome edge. The observed Sr/Ca
ratios in immature squid were considered to represent younger portions of the U-shaped pattern. In the present study we discuss
this pattern in relation to environmental and biological conditions of O. bartrami, which undertakes seasonal migrations between spawning grounds in the Subtropical Domain and feeding grounds in the Subarctic
Domain and Transitional Zone in the North Pacific Ocean. Although Sr/Ca ratios are potentially affected by ambient water temperature
and ontogenetic conditions, including somatic growth and statolith growth, it was impossible to evaluate each environmental
and biological effect separately, as variations in these factors are complicated and effects could be interdependent.
Received: 11 April 1997 / Accepted: 27 December 1997 相似文献
7.
The relationship between somatic growth and incremental growth of otoliths of Pacific saury, Cololabis saira (Brevoort), larvae under different temperature conditions was studied in the laboratory for three age groups (0 to 9, 10
to 20 and 20 to 30 d posthatch). Larvae were incubated from hatching to 9 d at 24, 20, and 16 °C. Further, larvae initially
reared at an ambient temperature of 21.7 °C were transferred to experimental temperatures of 22, 18, and 14 °C on Day 10 and
reared to Day 20 and similarly from Day 20 and reared to Day 30 posthatch. Growth trajectories of larvae sampled at the end
of the three experiments were back-calculated using the biological intercept method and compared to the measured values 0
and 5 d after the start of each experiment. Back-calculated knob length at the different temperatures indicated no significant
difference to the measured knob lengths except for the cases at 20 °C from hatching to 9-d-old larvae and at 14 °C from 20-
to 30-d-old larvae. The close correlation between somatic and otolith growth shown in this study indicated the feasibility
of estimating the growth history of Pacific saury larvae using otolith readings.
Received: 14 April 1999 / Accepted: 27 October 1999 相似文献
8.
We examined the effects of elevated temperature under different exposure periods on larval settlement and post-settlement
survival in scleractinian corals, Acropora solitaryensis and Favites chinensis. In the first experiment with the subtropical coral, A. solitaryensis, the numbers of larvae settling and those dead were examined daily for 5 days at 20, 23 (ambient), 26 and 29°C conditions.
Larval settlement of A. solitaryensis was initially greater at higher temperature conditions, but the peak in number of settled larvae shifted from 29 to 26°C
by day 5, due to ca. 90% post-settlement mortality at 29°C condition. In order to determine the effects under short-term exposure,
larvae of F. chinensis were exposed to 27 (ambient), 31 or 34°C only for one hour in the second experiment. The number of larvae settling for 24 h
after the exposure and their survivorship over subsequent week was monitored in the ambient temperature condition. Larvae
of F. chinensis exhibited greater settlement at higher temperature treatments and constantly low post-settlement mortalities (< ca. 17%)
in all temperature treatments, resulting in the highest number of settled larvae at 34°C treatment. These results suggested
two different effects of elevated temperature on the early stages of recruitment process of scleractinian corals; (1) the
positive effect on larval settlement and (2) the negative effect on post-settlement survival under prolonged exposure. 相似文献
9.
Life history and settlement preferences of the edible jellyfish Catostylus mosaicus (Scyphozoa: Rhizostomeae) 总被引:5,自引:0,他引:5
K. A. Pitt 《Marine Biology》2000,136(2):269-279
The life history and settlement preferences of larvae of Catostylus mosaicus (Scyphozoa: Rhizostomeae) (Quoy and Gaimard, 1824) were investigated in New South Wales, Australia, over a 2 mo period beginning
in November 1998. The life history consisted of an alternation between a sexual, medusoid stage and an asexual, polypoid stage,
and was similar to that described for other rhizostomes. Planula larvae were brooded by the adults. Approximately 4 d after
collection, larvae settled on a variety of substrata including wood, sandstone, shell, seagrass and glass, and metamorphosed
into four-tentacled polyps. The number of tentacles increased and polyps strobilated when they had between 12 and 20 tentacles.
Strobilation occurred within 15 d of settlement, but only polyps that settled on the concave surfaces of the shells strobilated.
Both monodisk and polydisk strobilation was observed. Ephyrae were raised for one month and were observed developing oral
arms. Polyps reproduced asexually via the formation of podocysts, by production of buds, and by partial fission.
Received: 30 April 1999 / Accepted: 27 August 1999 相似文献
10.
Free amino acids and energy metabolism in eggs and larvae of seabass, Lates calcarifer 总被引:3,自引:0,他引:3
Contents of free amino acids (FAA), protein and ammonium ions together with rates of ammonia excretion and oxygen consumption
were measured in order to study the role of FAA as an energy substrate in developing eggs and larvae of seabass (Lates calcarifer) maintained in seawater (30 ppt) at 28 °C without feeding. Initially eggs contained 25.3 nmol ind−1 of FAA of which 21.5 nmol was rapidly utilised by the developing eggs and larvae during the period up to 40 h post spawning
(PS) when nearly all the yolk had been resorbed. During the same period, a net increase in protein content of 1.7 μg ind−1 was observed, indicating that the major part of the amino acids lost from the free pool had been polymerised into body proteins.
Assuming that the balance of the FAA after protein synthesis was used entirely for energy metabolism, FAA appeared to be an
important energy substrate during the embryonic stages (2 to 16 h PS); after hatching, the contribution of FAA to energy metabolism
was less significant. From 50 h PS until the end of the study period at 100 h PS, amino acids derived from somatic protein
were used for energy metabolism. For the overall period from just after spawning up to 100 h PS, the data indicate that ca.
14% of the total aerobic energy metabolism was derived from amino acid catabolism.
Received: 26 September 1997 / Accepted: 1 April 1998 相似文献
11.
P. J. Krug 《Marine Biology》1998,132(3):483-494
A San Diego population of the opisthobranch mollusc Alderia modesta (Lovén, 1844) exhibits poecilogony, the presence of two development modes within a single species. In spring, half of the
adults spawned masses containing ∼300 eggs with a mean diameter of 68 μm. After 3 d, these egg masses hatched planktotrophic
veligers with a maximum shell dimension of 116 μm. The remaining adults spawned masses containing ∼30 eggs with a mean diameter
of 105 μm. These egg masses hatched after 5 to 6 d, releasing lecithotrophic larvae with a maximum shell dimension of 186 μm.
About 1% of field-collected adults produced mixed clutches containing a continuum of larval sizes, spanning the size extremes
of planktotrophy and lecithotrophy and hatching larvae with a mean maximum shell dimension of 152 μm. Adults producing planktotrophic
and lecithotrophic larvae were interfertile, and no hybrid breakdown was observed through the F3 generation. When starved,
adults which previously produced only lecithotrophic larvae switched to producing planktotrophic larvae or mixed clutches
with both planktotrophic and lecithotrophic larvae. Sequence-polymorphisms from a portion of the mitochondrial cytochrome
c oxidase I gene support the conclusion that the two reproductive morphs represent a single species. Most of the lecithotrophic
larvae and a small percentage of the larvae from mixed clutches were metamorphically competent within 3 d of hatching. A. modesta is the only molluscan species as yet known to have both planktotrophic and pelagic lecithotrophic development within a single
natural population.
Received: 14 August 1997 / Accepted: 11 April 1998 相似文献
12.
The mode of reproduction in Pocillopora verrucosa Ellis and Solander, 1786 varies between geographically isolated regions. This scleractinian coral is common along the KwaZulu-Natal
coast, and its reproductive mode and period of reproduction were assessed using histological preparations. The study was undertaken
from 1992 to 1994 and showed that P. verrucosa is a simultaneous hermaphrodite and broadcast spawner in KwaZulu-Natal. Gametogenesis occurs from October to January, with
the gametes maturing simultaneously so that spawning can be synchronised at new moon in January (mid-summer). Zooxanthellae
are present in the mature oocytes.
Received: 10 September 1997 / Accepted: 6 July 1998 相似文献
13.
A. L. Moran 《Marine Biology》1997,128(1):107-114
An understanding of spawning and larval development can be fundamental to interpreting the abundance, distribution, and population
structure of marine invertebrate taxa. Tegula funebralis (A. Adams, 1855), the black turban snail, has been the focus of numerous ecological studies on the Pacific coast of North
America. To date, there are only conflicting and anecdotal reports of spawning, and there is no information on larval or juvenile
development for this conspicuous and abundant species. On 19 September 1995, two individuals of T. funebralis were observed free-spawning gametes into seawater in tanks at the Oregon Institute of Marine Biology. Embryos and larvae
were subsequently reared to metamorphosis and beyond. Development was pelagic and similar to development described for other
trochids, and larvae were observed not to feed at any stage. Larvae began to metamorphose at 5.7 to 6.7 d and settled at 260
μm shell length. Juveniles grew ≃ 10 μm in shell length per day and appeared to feed on detritus. Juveniles lacked some adult
diagnostic shell characters, including two columellar nodes and a closed umbilicus. In the field, small (<3 mm) juveniles
occurred in the adult habitat on all sampling dates between October and March. Small juveniles were found only under rocks
and were most abundant under rocks partially buried in coarse sand, suggesting that juveniles may utilize a specific microhabitat
within the adult T. funebralis habitat.
Received: 7 October 1996 / Accepted: 17 October 1996 相似文献
14.
The wedge sole Dicologlossa cuneata (Moreau, 1881) is a coastal species that lives along the inner shelf waters of the Gulf of Cadiz down to a depth of 115 m.
Its fishery, the size composition of the exploited population, and its reproduction have been studied on the basis of data
acquired from commercial statistics from 1984 to 1994 and from sampling carried out during 1993 and 1994. The relative abundance
of the species and its geographic and bathymetric distribution have been examined by analysis of four trawl surveys carried
out from 1992 to 1994. D. cuneata is captured mainly by the trawl fleet, and to a lesser extent by gillnet gears. Wedge sole fishery has a marked seasonality.
Size-frequency distributions from commercial samples and from bottom-trawl surveys are very similar, ranging from 12 to 26 cm
total body length (TL). D. cuneata is a “repeat-spawner”. Peak spawning is from January to May. Females attain sexual maturity at 18 cm TL, while sexually mature
males have been observed at 15 cm TL. The flexibility of the spawning strategy of D. cuneata throughout its distribution range is discussed. The scarcity of small specimens in the monthly samples and sequential spawning
throughout the year prevented the estimation of growth parameters by means of length-frequency analysis. D. cuneata is present in greatest abundances in the sandy–muddy bottoms of the Guadalquivir River mouth at 15 to 30 m depth. Its optimum
habitat coincides with the principal commercial fishing grounds. The possibility of reproductive vertical migration is discussed,
but more precise data are needed before a viable hypothesis can be made.
Received: 1 July 1997 / Accepted: 27 November 1997 相似文献
15.
The post-release behaviour of eight black marlin (Makaira indica), caught by standard sportfishing techniques off the Great Barrier Reef, Australia, was investigated using ultrasonic telemetry.
Five marlin between 100 and 420 kg were successfully tracked for periods of 8 to 27 h. Of the three others tagged, one was
killed by a shark and two shed their tags, probably as the result of poor attachment. The black marlin spent most of their
time within 10 m of the surface, both day and night. During the day, however, they also spent some time between 40 and 140 m
depth. They rarely penetrated the thermocline, and then only briefly, remaining at temperatures no more than 8 C° below that
of surface waters. The deepest dives were to 178 m. Four of the five marlin tracked, initially moved offshore before heading
parallel to the shore, whereas the other marlin stayed close to the reef edge. The average mean swimming speeds over the ground
for entire tracks ranged from 0.7 to 1.02 m s−1.
Received: 17 January 1997 / Accepted: 16 June 1999 相似文献
16.
Between June 1994 and September 1996, a mark–recapture study was conducted in the Hinchinbrook Channel area of tropical northeastern
Australia to investigate the movements of the sparid fish Acanthopagrus berda. A total of 962 A. berda were tagged, 922 within a single estuary system, Deluge Inlet. No movements among estuaries were detected. Of the fish tagged
in Deluge Inlet, 12.9% were recaptured. Two movement regimes were detected: local movements (mostly <500 m) during non-spawning
times, and longer migrations (up to 3.12 km) during spawning seasons, to and from a spawning site at the estuary mouth. Although
there appeared to be a major spawning aggregation in the mouth of Deluge Inlet, ripe female A. berda were present in upstream sites, indicating that spawning probably occurs there also. This contrasts to the situation in South
Africa, where A. berda is reported to spawn only close to estuary mouths. Differences such as this highlight our limited knowledge of variations
in the reproductive biology of widespread species such as A. berda.
Received: 25 November 1997 / Accepted: 10 September 1998 相似文献
17.
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
18.
Otolith microstructure and microchemistry were examined in juveniles of American (Anguilla rostrata) and European (A. anguilla) eels. Otolith increment width markedly increased from age 132 to 191 d (156 ± 18.9 d; mean ± SD) in A. rostrata and 163 to 235 d (198 ± 27.4 d; mean ± SD) in A. anguilla, both of which were coincident with drastic decreases in otolith Sr:Ca ratios, suggesting that metamorphosis from leptocephalus
to glass eel began at those ages in each species. The duration of metamorphosis was estimated to be 18 to 52 d from otolith
microstructure, for both species studied. Ages at recruitment were 171 to 252 d (206 ± 22.3 d; mean ± SD) in A. rostrata and 220 to 281 d (249 ± 22.6 d; mean ± SD) in A. anguilla. In these two species, positive linear relationships were found in ages between the beginning of metamorphosis and recruitment,
suggesting that early metamorphosing larvae recruited at younger ages. Duration of the leptocephalus stage to recruitment
in A. anguilla was about 40 d longer than that in A. rostrata. The geographical segregation between the two species in the Atlantic Ocean seems to be involved in the differences in the
duration of the leptocephalus stage (age at metamorphosis).
Received: 8 November 1999 / Accepted: 8 May 2000 相似文献
19.
Cod (Gadus morhua L.) eggs may develop and hatch within temperatures of −1.5 to 12 °C, but little is known about the effects of very low temperatures
on larval characteristics. Eggs of the Northeast Arctic cod (Gadus morhua) were incubated at 1, 5 or 8 °C from Day 1 after fertilisation until hatching, and transferred to 5 °C after hatching. Histological
samples of the axial musculature were taken at hatching and 5 d after hatching, and the data on muscle cellularity from these
samples were related to survival and hatching, size, developmental data and viability of the yolk sac larvae. All larvae hatched
at the same developmental stage. Incubation of eggs at 1 °C produced shorter larvae with a larger yolk sac and more, small
deep fibres at hatching than larvae from eggs incubated at 5 or 8 °C. The larval size difference was still present 5 d after
hatching, a time at which the larvae from 1 °C-incubated eggs were less developed and less resistant to an acute viability
stress test (65 ppt salinity). Although there were no differences between temperature groups in number and size of muscle
fibres 5 d after hatching, the deep fibres of the 1 °C-group contained less myofibrils than the two other groups. The phenotype
of the larvae at hatching was thus affected within these incubation temperatures. Although all groups were transferred to
the same temperature after hatching, the lowest egg incubation temperature (1 °C) still had a negative effect 5 d after hatching,
as these larvae were both smaller, less resistant to stress and had less functional muscles at the time of first feeding.
Our conclusion is therefore that 1 °C is close to, or below, the lower thermal tolerance limit for normal functional development
of Northeast Arctic cod. The results are discussed in relation to larval viability and recruitment of this species in the
wild.
Received: 4 February 1998 / Accepted: 10 July 1998 相似文献
20.
Effect of amino acids on the swimming activity of newly hatched turbot larvae (Scophthalmus maximus)
The swimming behaviour of newly hatched turbot (Scophthalmus maximus L.) larvae was observed in artificial seawater (ASW) and in solutions of 21 l-amino acids at a concentration of 10−5
M. The behaviour of 20 larvae was analysed in each solution. Each larva was observed for 1 min. Individual movements were recorded
on video and analysed using a computer-assisted program. The larvae swam in convoluted, randomised three-dimensional paths,
rested and started swimming again. There were large variations in the swimming behaviour of turbot larvae during ontogeny.
In ASW the mean frequency of trajectories longer than a body length of 4 mm larva−1 min−1 increased from 1.2 at Day 1, to 10 at Day 4. Analysing the data (Dunnett's method) revealed that the frequency of swimming
trajectories increased in the presence of glycine, histidine and glutamine, and decreased in the presence of proline. The
total distance swum increased for glycine but decreased for proline. The threshold concentration for glycine detected by turbot
larvae was 10−5
M. The straightness index did not change in the presence of the amino acids. The possible role of these changes in behaviour
is discussed.
Received: 12 June 1997 / Accepted: 13 January 1998 相似文献