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1.
M. Thiel 《Marine Biology》1998,132(2):209-221
The suspension-feeding amphipod Dyopedos monacanthus (Metzger, 1875) is a common epibenthic amphipod that lives on self-constructed “mud whips” (built from filamentous algae,
detritus and sediment particles) in estuaries of the northern North Atlantic Ocean. The population biology of D. monacanthus at a shallow subtidal site in the Damariscotta River Estuary (Maine, USA) was examined between July 1995 and July 1997. The
resident population at the study site was dominated by adult females during most months of the year. High percentages of subadults
were found in late summer/early fall. Often, between 10 and 20% of the adult females were paired with males, and the percentage
of ovigerous females varied between 40 and 100%, indicating continuous reproduction. The percentage of parental females varied
between 40 and 80% during most months, but dropped to levels below 20% during summer/early fall. The average size of amphipods
on their own mud whips was ∼4 mm during the summer/early fall, after which it increased continuously to >7.0 mm in March or
April, and then dropped again. In March and April, the average number of eggs and juveniles female−1 was ∼100 eggs and 55 juveniles, while during the summer/early fall the average number of eggs female−1 was <20 and that of juveniles female−1 was <10. Many juveniles grew to large sizes (>1.4 mm) on their mothers' whips in winter/early spring but not in the summer/fall.
The average number of amphipods at the study site was low in late summer/early fall (<50 individuals m−2), increased steadily during the winter, and reached peak densities of >3000 individuals m−2 in April 1996 (>1600 individuals m−2 in May 1997), after which densities decreased again. The decrease of the D.␣monacanthus population at the study site coincided with a strong increase of amphipods found pelagic in the water column. This behavioural
shift occurred when temperatures increased and benthic predators became more abundant and active on shallow soft-bottoms,
suggesting that D. monacanthus at the study site is strongly affected by predation. The effects are direct (by predation on amphipods) and indirect (by
reducing duration of extended parental care and enhancing pelagic movements). Both extended parental care and pelagic movements
are important behavioural traits of D.␣monacanthus (and other marine amphipods), and significantly affect its population dynamics.
Received: 18 January 1998 / Accepted: 27 May 1998 相似文献
2.
M. Thiel 《Marine Biology》1998,132(1):107-116
The reproductive traits of a deposit-feeding amphipod that engages in extended parental care were examined. At the study
site in Lowes Cove, Maine, USA, Casco bigelowi (Blake, 1929) occurred in highest densities in soft sediments just below mean low water (MLW). During most months, the sex
ratio was ≃1. Many females hosted males in their burrows throughout the summer, but after fertilization of females in September,
all adult males disappeared from the study area. In October almost 80% of the females were ovigerous, and in November about
the same percentage was parental, i.e. caring for juveniles in their burrows. The females produced only one brood each in
late fall which they accommodated in their burrows for 2 mo or longer. The average number of juveniles per female was ∼20
in November, and continuously decreased until January. Juveniles reached sizes >10 mm length in the maternal burrows. In early
December the first juveniles were found in their own burrows, but major recruitment took place in late December and January.
It is concluded that for C. bigelowi, the delay of recruitment into the winter months with low predation pressure and the large offspring size at this time are
major advantages gained by extended parental care. C. bigelowi is host to the peritrich ciliate Cothurnia sp. on its gills, and during the summer months >70% of all amphipods had ciliates on their gills. Juveniles still living
in their mother's burrows showed infestation rates similar to that of the parent; those of highly infested mothers were more
heavily infested than those of “clean” mothers. Facilitated epibiont transmission during intimate and long-lasting (2␣mo)
parent–offspring associations may be a consequence of extended parental care.
Received: 25 November 1997 / Accepted: 14 April 1998 相似文献
3.
Reproductive biology of a wood-boring isopod, Sphaeroma terebrans, with extended parental care 总被引:1,自引:0,他引:1
M. Thiel 《Marine Biology》1999,135(2):321-333
The isopod Sphaeroma terebrans Bate, 1866 burrows in aerial roots of the red mangrove Rhizophora mangle L. The burrows serve as shelter and as a reproductive habitat, and females are known to host their offspring in their burrows.
I examined the reproductive biology of S. terebrans in the Indian River Lagoon, a shallow lagoon stretching for ∼200 km along the Atlantic coast of Florida, USA. Reproductive
isopods were found throughout the year, but reproductive activity was highest in the fall and during late spring/early summer.
During the latter periods, large numbers of subadults established their own burrows in aerial roots. The average numbers of
S. terebrans per root were high during the fall, but decreased during the winter and reached lowest levels at the end of the summer. Females
reached maturity at a larger size than males, but also grew to larger sizes than the males. The average size of females varied
between 8 and 10 mm, the average size of males between 6.5 and 8.5 mm. The number of embryos female−1 was strongly correlated with female body length. No indication for embryo mortality during development was found. Parental
females (i.e. with juveniles in their burrows) hosted on average between 5 and 20 juveniles in their burrows (range 1 to 59).
Most juveniles found in female burrows were in the manca stage and 2 to 3 mm in body length. Juveniles did not increase in
size while in the maternal burrow, and juveniles of similar sizes could also be found in their own burrows. Males did not
participate in extended parental care, since most of them left the females after copulation. Many females that were born in
the summer produced one brood in the fall and a second during winter/early spring. Females that were born in the fall produced
one brood during spring/early summer, but then probably died. Extended parental care in S. terebrans is short compared to other peracarid crustaceans. It is concluded that this reproductive strategy in S. terebrans serves primarily to shelter small juveniles immediately after they emerge from the female body, when their exoskeleton is
still hardening and their physiological capabilities are still developing. Thus, in S. terebrans, extended parental care probably aids to protect small juveniles from adverse physical conditions in their subtropical intertidal
habitat.
Received: 9 December 1998 / Accepted: 24 June 1999 相似文献
4.
Some ecological observations on fishes associated with drifting seaweed off Tohoku coast,Japan 总被引:2,自引:0,他引:2
Fishes associated with drifting seaweed were sampled in the Tohoku area, northwest Pacific, in late spring 1988, to analyse the community structure and ecological relationships of the dominant species.Seriola quinqueradiata Temminck et Schlegel was the dominant species and its escort was composed ofThamnaconus (Navodon)modestus, Sebastes inermis, Hyperoglyphe japonica andEnedrias nebulosus. E. nebulosus, which fed essentially on Gammarid crustaceans, was collected mainly in Sendai Bay; the other species, found in offshore water, were plankton feeders and did not exhibit any strong competition, indicating close cohabitation. The abundance of drifting seaweed in the Tohoku area peaked in May–June and decreased in July; they seemed to come from the nearest coast. JuvenileS. quinqueradiata (> 15 cm long) were collected with set nets in Sendai Bay during summer. They seemed to use drifting seaweed (along with the warm Kuroshio current) as a means of transportation during their migration from the southern spawning ground to northern Tohoku area. Drifting seaweed could be considered as a nursery, and the association of fishes with floating algae might have an influence on species recruitment. 相似文献
5.
M. Thiel 《Marine Biology》1997,130(2):249-258
Leptocheirus pinguis (Stimpson, 1853) is a widely distributed, abundant, endobenthic amphipod that engages in extended parental care, i.e. females
host their juveniles in their burrows for extended time periods. I examined reproduction and population biology of L. pinguis at mean low water (MLW) in muddy sediment in Lowes Cove, Maine, USA. Cores around individual burrows were taken monthly in
1994 and 1995, and four seasonal samples were taken at different tidal heights. During the major reproductive periods in spring/early
summer and in the fall, females produced several consecutive broods and hosted growing offspring in their burrows. Juveniles
remained in their mothers' burrows until they reached a length of 5 mm (approximately one-third adult size) or more. At the
study site, the majority of amphipods in individual burrows were adult females. Following the main reproductive periods, subadult
individuals were found in their own burrows, but densities did not increase following the reproductive period in spring/early
summer 1994, probably because large numbers of L. pinguis emigrated via the water column between June and December. L. pinguis is an annual species. Many members of the cohort born in spring/early summer start reproducing in the fall, and survive until
the following spring when they produce several broods. Members of the cohort born in the fall start reproducing the following
spring and also produce several consecutive broods. Both the spring/early summer and fall cohorts die off after the major
reproductive period in the following spring/early summer. High standing stocks of microphytobenthos occur in soft-bottoms
at MLW, and I conclude that L. pinguis can engage in extended parental care there because its food is abundant year-round. The limited expandability and low stability
of burrows in soft-bottoms at MLW do not permit long persistence of parent–offspring groups in L.␣pinguis.
Received: 27 March 1997 / Accepted: 30 July 1997 相似文献
6.
The predation impact of the two chaetognaths Eukrohnia hamata and Sagitta gazellae on mesozooplankton standing stock were investigated in three depth layers during two 24 h stations occupied in the vicinity
of Marion Island in late austral summer (April/May) 1986. The zooplankton community at both stations was dominated by small
copepods (Oithona spp., Microcalanus spp.), which accounted for >95% of total zooplankton abundance. Chaetognaths comprised <2% of total zooplankton abundance.
E. hamata constituted >95% of the total chaetognath stock. The general trend in both species was decreasing abundance with increasing
depth, which appeared to be correlated to the distribution of copepods (r
2 = 0.45; P <0.05). Gut-content analysis showed that copepods (mainly Oithona spp., Calanus spp. and Rhincalanus gigas) and ostracods were the main prey of both species, accounting for 87 and 61% of the total number of prey in E. hamata and S.␣gazellae stomachs, respectively. In the guts of S.␣gazellae, pteropods (Limacina spp.) and chaetognaths were also well represented. The mean number of prey items (NPC) for E. hamata ranged from 0.02 to 0.06 prey individual−1 which corresponds to an individual feeding rate (Fr) of between 0.05 and 0.12 prey d−1. For S.␣gazellae, the NPC values were higher, varying between 0.04␣and 0.20 prey individual−1, or between 0.15 and 0.76 prey d−1. The daily predation impact of the two chaetognaths was estimated at between 0.3 and 1.2% of the copepod standing stock or
between 7 and 16% of the daily copepod production. Predation by S. gazellae on chaetognaths accounted for up to 1.6% of the chaetognath standing stock per day.
Received: 26 November 1996 / Accepted: 31 October 1997 相似文献
7.
To examine the impact of development rate on swimming performance, escape response, and morphology, yolk-sac larvae of American
plaice (Hippoglossoides platessoides, Fabricius) were reared at two temperatures (5 and 10 °C). Videomicroscopy and silhouette collimation videography were used
to examine swimming, escape behaviour, and morphology (standard length, finfold area, and yolk-sac area) of individual larvae.
Larvae were examined from 0 d post hatch (dph) to 14 dph for the 5 °C treatment group and from 0 to 6 dph for the 10 °C treatment
group (3 August to 17 August 1996). Since larvae were not fed, yolk-sac reserves were essentially exhausted by 14 and 6 dph
for the 5 and 10 °C treatment groups, respectively. To control for the effect of testing temperature on behaviour, larvae
from each temperature treatment were tested at both 5 and 10 °C. Testing temperature had an effect on some swimming parameters
but not on escape response. Swimming performance, escape response, and morphology varied with age, while only morphology and
escape response varied with development rate. Morphology and swimming performance, and morphology and escape response were
found to be correlated as determined by canonical correlation. This study suggests that both types of swimming behaviours
should be examined when developing models of the impacts of predation on the early life history of larval fish.
Received: 13 September 1999 / Accepted: 21 June 2000 相似文献
8.
Five pelagic Halobates species occupy a vast area from 40∘ north to 40∘ south in the three major oceans. Oceanic diffusion, constantly acting to disperse these insects, must be an important factor
in determining their life history and distribution. We investigated the effects of oceanic diffusion on the following aspects
of these insects. (1) The estimated radius of a patch of Halobates could be expanded by oceanic diffusion alone from an initial point of origin to 1250 km in 60 d. This distance is about 1/12
of the maximum distributional range of H. micans in the Pacific Ocean. Mutual encounter rates due to oceanic turbulence could be as high as 11 d−1 even at low population densities (100 ind km−2). This suggests that individuals from their original habitat could find mates even when they had been carried a long distance.
Thus, extensive gene mixing may occur over the whole range of a species' distribution. (2)␣Estimated growth rates are rather
low (0.0026 to 0.0079 d−1) compared with those of other insects. However, they are offset by a long life span (over 90 d) and an extended oviposition
period (perhaps over 2␣months). Thus, pelagic Halobates spp. appear to have adopted a strategy of slow growth and prolonged longevity to cope with living in an unstable physical
environment that is constantly disturbed by storms and winds.
Received: 5 February 1995 / Accepted: 30 October 1997 相似文献
9.
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
10.
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
11.
When symbiotic dinoflagellate algae (Symbiodinium sp., isolated from the coral Plesiastrea versipora) were incubated with NaH14CO3 in the light in seawater, they released 22.69±9.16 nmol carbon/106 algae. Release of photosynthetically fixed carbon was stimulated more than six-fold for algae incubated in host-tissue homogenate
(148.54±97.03 nmol C/106 algae) and more than four-fold (102.00±49.16 nmol C/106 algae) for algae incubated in a low molecular weight fraction (≤1 000 M
r
) prepared from host homogenate. Soluble released 14C-labelled products, as determined by chromatography and autoradiography, were the same when algae were incubated in either
host homogenate or the low molecular weight fraction. After 4 h incubation in the light (300 mol photons m−2 s−1),␣intracellular␣glycerol increased in algae incubated with the low molecular weight fraction (an increase of 0.39 to␣0.67 nmol glycerol/106 algae) compared with little or no increase in algae incubated in seawater (0 to 0.12 nmol glycerol/106 algae). Partial inhibition of triglyceride synthesis (up to 51%) was also observed when algae were incubated in the low molecular
weight fraction. All these effects are the same as those observed when algae were incubated in host homogenate. These data
indicate that the “host release-factor” activity of P.␣versipora is a compound of low molecular weight.
Received: 13 February 1997 / Accepted: 24 October 1997 相似文献
12.
The annual occurrence of hypoxia (<25% oxygen saturation) in the bottom waters along the Swedish west coast coincides with
the postlarval settlement of Norway lobster, Nephrops norvegicus (L.). This study investigates behaviour and the experimental effects of low oxygen concentrations in juvenile N. norvegicus of different ages. All experimental individuals were reared to the juvenile (postlarval) stage in the laboratory and then
given sediment as a substratum. Behavioural responses to low oxygen concentrations were tested in early and late Postlarvae
1 exposed to normoxia (>80% oxygen saturation, pO2 > 16.7 kPa), moderate hypoxia (30% oxygen saturation, pO2 = 6.3 kPa) and hypoxia (25% oxygen saturation, pO2 = 5.2 kPa). The experiments were run for a maximum period of 24 h or until individuals died. Behaviour was studied using
sequential video recordings of four behavioural activities: digging, walking, inactivity or flight (escape swimming up into
the water column). Behaviour and mortality changed with lowered oxygen concentrations; energetically costly activities (such
as walking) were reduced, and activity in general declined. In normoxia, juveniles initially walked and then burrowed, but
when exposed to hypoxia they were mainly inactive with occasional outbursts of escape swimming. To increase oxygen availability
the juveniles were observed to raise their bodies on stilted legs (similar to adults in hypoxic conditions), but oxygen saturations
of 25% were lethal within 24 h. The results suggest that the main gas exchanges of early postlarval stages occur over the
general body surface. Burrowing behaviour was tested in Postlarvae 1 and 2 of different ages held in >80% oxygen saturation
for 1 wk. The difference in time taken to complete a V-shaped depression or a U-shaped burrow was measured. The results showed
a strong negative relationship between postlarval age and burrowing time, but all individuals made a burrow. Juveniles were
more sensitive to hypoxia than adults. Thus, the possible consequences of episodic hypoxia for the recruitment of Nephrops norvegicus and for the recolonization of severely affected areas are discussed.
Received: 4 August 1996 / Accepted: 11 October 1996 相似文献
13.
The toxicity of fenitrothion was determined in larvae (nauplii, Zoeae 1 to 3, Mysis 1 to 3), postlarvae (PL stages) and juvenile
shrimp (Penaeus japonicus Bate), in two media, seawater (SW) and diluted seawater (DSW) (1100 and 550 mosM kg−1, ≃ 37 and 19‰ S). The effects of fenitrothion on the osmoregulatory capacities (OC) of juveniles were recorded. A gill and
epipodite histopathological study was also conducted. For larvae in seawater, 24 and 48 h LC50s ranged from 32.9 μg l−1 (Zoeae 2) to 10.7 μg l−1 (Mysis 3), and from 3.9 μg l−1 (Zoeae 3) to 2.0 μg l−1 (Mysis 3), respectively; 48 and 96 h LC50s in postlarvae (PL) at the same salinity ranged from 1.8 μg l−1 (PL1) to 0.6 μg l−1 (PL5), and from 0.3 μg l−1 (PL7) to 0.4 μg l−1 (PL15). In juveniles, 96 h LC50s were 0.8 μg l−1 in seawater and 1.5 μg l−1 in diluted seawater. From hatching to juvenile stages, the overall trend was a rapid decrease (from nauplii to PL5–PL7) followed
by a slight increase (from PL7 to PL15 and juveniles) in the shrimp's ability to tolerate the insecticide. In juveniles kept
in seawater and in diluted seawater, fenitrothion decreased the osmoregulatory capacity (OC = difference between the hemolymph
osmotic pressure and the osmotic pressure of the medium) at both lethal and sublethal concentrations. This effect was time-
and dose-dependent. In SW, the decrease in hypo-OC was ˜ 25% at sublethal concentrations and ˜ 35% at the 96 h LC50. In DSW, the decrease in hyper-OC was ˜ 10 to 15% at sublethal concentrations. In SW, shrimp were able to recover their OC
in less than 48 h when transferred to water free of pesticide. In DSW, recovery at 48 h was only possible after exposure to
the lowest tested sublethal concentration. Haemocytic congestions (thrombosis) of the gills, lamellae necrosis and other alterations
of gills and epipodites (breakage of the cuticle, reduction of the hemolymph lacunae) were noted in juveniles exposed to lethal
and sublethal concentrations of fenitrothion.
Received: 7 October 1996 / Accepted: 13 November 1996 相似文献
14.
K. M. Swadling J. A. E. Gibson D. A. Ritz P. D. Nichols D. E. Hughes 《Marine Biology》1997,128(1):39-48
Chlorophyll a, primary productivity and grazing by copepods on phytoplankton were measured in the upper water column during the summer
of 1994/1995 at a coastal site near Davis Station, East Antarctica. Chlorophyll a was at a maximum in mid-December, then dropped markedly as the coastal fast ice melted and broke‐out. Phytoplankton biomass
increased again from mid‐ to late‐February. Copepods accounted for at least 65% of zooplankton biomass in the water column
before sea ice break‐out, whereas larval polychaetes and ctenophores dominated after ice break‐out. Oncaeacurvata was the numerically dominant species throughout the study. The highest grazing rate (8.7 mg C␣m−3␣d−1) was recorded on 21 December when O.␣curvata accounted for 64% of the total. Grazing had decreased markedly by 28 December (0.9 mg C m−3 d−1); again O. curvata accounted for over 50% of the total ingested. Copepod grazing increased after ice break-out until the last experiment on
20 February (⋍5 mg C␣m−3␣d−1). The main species responsible for grazing during this period were O. curvata, Oithonasimilis, Calanoidesacutus and unidentified copepod nauplii. It was estimated that copepods removed between 1 and 5% of primary productivity.
Received: 11 October 1996 / Accepted: 22 October 1996 相似文献
15.
A. I. Arkhipkin 《Marine Biology》1997,129(1):103-111
Statolith microstructure was studied in 56 Ancistrocheirus lesueurii (25 to 423 mm of mantle length, ML) caught in the central-east Atlantic. Statolith growth increments were grouped into three
main growth zones, distinguished mainly by increment width. The second transition in the statolith microstructure (from Zone
2 to Zone 3) coincides with the life history shift from epipelagic and upper mesopelagic to a bathyal habitat. Second-order
bands (mean 27.65 growth increments) and sub-bands (mean 13.6 growth increments) within statolith microstructure appeared
to be related to the lunar cycle. Striking sexual dimorphism is reflected in the age and growth rates: males live ca. 1 yr,
while females only start maturing at this age and obviously live >1.5 yr. A. lesueurii is a slow growing squid, attaining 25 to 30 mm ML at the age of 100 d. After ontogenetic migrations into bathypelagic waters
at ML > 30 to 35 mm, growth rates gradually decrease to the minimum known values for squids. Based on back-calculated hatching
dates, A. lesueurii hatches throughout the year with a peak between November and March.
Received: 28 August 1996 / Accepted: 31 January 1997 相似文献
16.
Larvae of the marine cheilostomatid bryozoan Bugula neritina (L.) were prevented from settling for 1, 4 and 8 h by mechanical agitation, following which settlement and metamorphosis
success were examined. Settlement rates were significantly affected by swimming time, which decreased from 100% after 2 h
to 93.7 ± 4.3% after 8 h. Similarly, metamorphosis to the feeding ancestrula was significantly impaired following a swimming
time of 8 h, declining from 93.7 ± 4.3% after 1 h to 65.9 ± 7.0% after 8 h. The resultant colonies grew well for the first
3 wk, following which time, growth patterns became erratic. Growth rate was in all cases highly variable, and did not correlate
with enforced swimming times. Larval protein composition was examined after 1, 4 and 8 h swimming time, and post-larval composition
1, 2, 5, 24 and 48 h after settlement using sodium-dodecyl-sulphate polyacrylamide-gel electrophoresis (SDS-PAGE). Individual
protein content was measured using a densitometer. Larvae did not consume protein during swimming, however a protein measuring
170 kdaltons was consumed during metamorphosis. These results are discussed in the context of larval settlement and energetics.
Received: 19 July 1998 / Accepted: 3 December 1998 相似文献
17.
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
18.
Feeding, metabolism and growth in the Antarctic limpet, Nacella concinna (Strebel 1908) 总被引:2,自引:0,他引:2
Post-prandial increases in metabolism, the specific dynamic action of feeding (SDA), were evaluated in the Antarctic limpet
Nacella concinna. O2 consumption rose to a peak value 2.3 times higher than pre-feeding standard metabolic rates. This peak rise is low for marine
ectotherms, but is typical of polar species. There were three peaks in the SDA, the first lasted only for the 1st day, was
caused by handling, and was minor. The second was the major peak. It lasted from post-prandial days 4–9 inclusive, and accounted
for around 70% of the SDA response. The third peak lasted from day 11 to day 15 and accounted for 30% of the total SDA. A
15-day SDA is much longer than values for temperate species, but is again typical for polar marine ectotherms. NH3 excretion declined post-prandially from around 0.4 μmol animal−1 h−1 to values between 0.025 and 0.223 μmol animal−1 h−1 throughout the SDA. The total O2 consumed in the SDA was 90.2 μmol O2, which converts to 44.7 J of energy. This was 45–50% of the energy consumed in the meal (93.5 J). Pre-feeding O:N ratios,
after 26 days without food, were around 1, indicating protein as the sole metabolic substrate prior to initiating the SDA.
After feeding, O:N ratios rose to between 2.5 and 19, indicating significant use of lipid or carbohydrate from the food. Experiments
were conducted in ambient seawater with enhanced levels of Sr (SrCl added at 800 mg kg−1), and limpets were fed microalgal films also grown in enhanced Sr media. Sr incorporated in the shells during the experiment
allowed the measurement of shell increments deposited during the SDA. Between five and eight microgrowth bands were present
in the Sr-enhanced increments, which was similar to the number of days in the second SDA peak. The mean shell increment laid
down was 17.6 μm. Estimating tissue deposition from measured growth increments and published ash-free dry mass (AFDM) to length
relationships produced a value of 0.81 mg AFDM, which converted to 26.4 J of energy, or 25–30% of the energy ingested in the
meal. Estimates of growth increments associated with a single SDA have not previously been possible. Overall energy used in
the SDA and tissue deposition accounted for 75–80% of the energy ingested; the remainder was probably accounted for by unmeasured
costs such as mucus production.
Received: 6 June 2000 / Accepted: 20 September 2000 相似文献
19.
In the present study 670 individuals of Gonatus onyx (Cephalopoda: Teuthoidea) were observed in Monterey Bay, California from a remotely operated vehicle. The vertical distribution
of this species was bimodal, with peaks at 400 and 800 m depth during the day and 300 and 500 m during the night. The bimodal
distribution reflects a life stage shift between younger, schooling juveniles living in shallower water and older, solitary
adults which live deeper. Ontogenetic changes in behavior associated with this life stage shift are reflected in the physiology
of the organisms as well. Both aerobic and anaerobic metabolism, as estimated using mitochondrial and glycolytic enzymes,
decline with increasing body mass, suggesting reduced locomotory capacity in deeper-living adults. Oxygen consumption rates
were also determined in relation to oxygen partial pressure. Oxygen consumption regulation was similar between juvenile and
adult squids. The critical oxygen partial pressures (29 to 30 mmHg) correspond precisely to the oxygen concentrations found
at the depth of maximal abundance for day and night populations of juveniles and adults, respectively. Behavioral and physiological
changes with ontogeny of G. onyx are believed to result from reduced visual predator/prey interactions in the light-limited deep sea.
Received: 7 February 1999 / Accepted: 26 January 2000 相似文献
20.
Zooplankton responses to hypoxia: behavioral patterns and survival of three species of calanoid copepods 总被引:2,自引:0,他引:2
Seasonally recurrent and persistent hypoxic events in semi-enclosed coastal waters are characterized by bottom-water dissolved
oxygen (d.o.) concentrations of < 2.0 ml l−1. Shifts in the distribution patterns of zooplankters in association with these events have been documented, but the mechanisms
responsible for these shifts have not been investigated. This study assessed interspecific differences in responses to hypoxia
by several species of calanoid copepods common off Turkey Point, Florida, USA: Labidocera aestiva (Wheeler) (a summer/fall species), Acartia tonsa (Dana) (a ubiquitous year-round species), and Centropages hamatus (Lilljeborg) (a winter/spring species). Under conditions of moderate to severe hypoxia 24-h survival experiments were conducted
for adults and nauplii of these species from August 1994 to October 1995. Experiments on adults used a flow-through system
to maintain constant d.o. concentrations. Adults of A. tonsa showed no decline in survival with d.o. as low as 1.0 ml l−1, sharp declines in survival at d.o. = 0.9 to 0.6 ml l−1, and 100% mortality with d.o. = 0.5 ml l−1. Adults of L. aestiva and C. hamatus were more sensitive to oxygen depletion: both species experienced significant decreases in survival for d.o. = 1.0 ml l−1. Nauplii of L. aestiva and A. tonsa showed no significant mortality with d.o. = 1.1 to 1.5 ml␣l−1 and d.o. = 0.24 to 0.5 ml l−1, respectively. In addition, experiments investigating behavioral avoidance of moderate to severe hypoxia were carried out
for adults of all three species. None of the three species effectively avoided either severely hypoxic (d.o. < 0.5 ml l−1) or moderately hypoxic (d.o. ≈ 1.0 ml l−1) bottom layers in stratified columns. These results suggest that in␣nearshore areas where development of zones of d.o. < 1.0 ml
l−1 may be sudden, widespread, or unpredictable, patterns of reduced copepod abundance in bottom waters may be due primarily
to mortality rather than avoidance.
Received: 31 August 1996 / Accepted: 24 September 1996 相似文献