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1.
Field experiments were conducted from dusk to dawn off St. John (18° 18′ 59.32″ N, 64° 43′ 24.5″ W) and Guana Island (18°
28″ 28.31″ N, 64° 34′ 30.83″ W), Virgin Islands from June through August 2008-2010 to assess the sensory cues used by the
nocturnal/crepuscular fish-parasitic gnathiid isopod, Gnathia marleyi, to locate fish hosts. Experimental traps providing both visual and olfactory cues from live French grunts (Haemulon flavioliniatum) attracted significantly more gnathiids than traps providing only visual cues or control traps (empty or with a rock), which
were not significantly different from each other. In another experiment, traps providing both cues and only olfactory cues
attracted significantly more gnathiids than empty control traps, but were not significantly different from each other. Our
findings suggest that during nocturnal and crepuscular periods, visual cues provided by resting or slow-moving fish are not
alone sufficient to attract gnathiids, while olfactory cues alone are. The traps designed for this study offer a new method
of sampling free-living gnathiid isopods. 相似文献
2.
The endogenous rhythm of oxygen consumption in juvenile spotted sea bass (Lateolabrax sp.) was measured to test the effects of sudden changes in salinity on the metabolic activity. Mean oxygen consumption rates
of this euryhaline fish decreased by 13.5 to 16.0% and 25.3 to 36.4% when they were transferred from 31.5 to 15‰ seawater
and to fresh water (0‰), respectively. The maximum rate of oxygen consumption was observed between 18:00 and 19:00 hrs local
time, 1 to 2 h before sunset, even though they were kept in constant darkness. The peaks of oxygen consumption occurred in
23.2- and 23.3-h intervals, which correspond with a circadian rhythm, as revealed by maximum entropy spectral analysis. A
markedly weakened rhythm in oxygen consumption occurred from 8 to 10 d after onset of the experiments. This study indicates
that spotted sea bass can withstand sudden drops in salinity from 31.5‰ to fresh water, and yet maintain a regular though
somewhat dampened endogenous rhythm of oxygen consumption.
Received: 16 June 1997 / Accepted: 3 February 1998 相似文献
3.
Gnathiid isopods are one of the most abundant groups of ectoparasites on coral reef fishes. They, and other isopods, have
been shown to significantly affect the health and behaviour of many reef fish. Whether isopod emergence differs among habitats
on coral reefs is not known. In this study, we measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera)
in six habitats at two sites at Lizard Island during new moon periods in March and December 2004. Isopods were collected from
the periphery and centres of micro-reefs, patch reefs, continuous reefs, and from inter-reefal habitats (sand or rubble) with
1 m2 emergence traps. Sites (Casuarina and Coconut Beach) were located on opposite sides of Lizard Island. Live gnathiids were
collected with light traps in November 2005 to investigate species differences between sites. At both sites, the most abundant
gnathiid species was exclusive to that site. More gnathiid larvae emerged at night, and emergence of fed gnathiids (pranizae)
and flabelliferan isopods was almost exclusively nocturnal. Diurnal emergence was greater at Coconut Beach than Casuarina
Beach. Although emergence counts were not consistently affected by parameters such as habitat, site, or sampling period, gnathiid
size and feeding state were. Where significant differences existed, gnathiids were larger and more often fed over reef borders
than centrally. We suggest first stage larvae (Z1) have the largest influence on total abundance and are patchily distributed
in accordance with adults from which they have recently hatched. As later stage larvae depend on fish, more successful (fed)
and older larvae are found on the edges of reefs where appropriate hosts may be more abundant, or predation is lower. Gnathiids
were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicates
that their distributions may be better predicted by very fine scale differences in substrate or that aggregations are the
result of gregariousness and may be difficult to predict on the basis of substrate. Emergence traps collected comparatively
few parasitic flabelliferan isopods. This community differed greatly from the previously described community of scavenging
isopods at Lizard Island. These differences are probably the result of differences in trapping methodology. 相似文献
4.
Investigations of factors affecting feeding success in fish larvae require knowledge of the scales of variability of the
feeding process itself and the indices used to assess this variability. In this study, we measured short-term (diel) variability
in feeding rates of wild haddock (Melanogrammus aeglifinus) larvae four times per day during a 10-d cruise in the northern North Sea. Feeding activity was evaluated using indices of
gut fullness, prey digestive state and biochemical measurements (tryptic enzyme activity). The gut fullness and the enzyme
activity indices indicated moderate to high rates of food consumption throughout the cruise. Time series analysis of the three
indices showed significant diel variability in all indices and enabled identification of significant lags between food uptake
and peak digestive enzyme activity. The typical pattern of food consumption and digestion was characterized by maximal ingestion
of prey early in the evening (19:00 hrs) and peak digestive enzyme activity at 01:00 hrs. The time scale over which enzyme
activities reacted to prey ingestion was ca. 6 h, and is consistent with expectations from controlled laboratory experiments
with other larval fish species. Significant diel variability in tryptic enzyme activity suggests that attempts to relate this
measure of feeding success to other variables (e.g. food concentrations) should take care to accommodate natural cycles in
feeding activity before making statistical comparisons.
Received: 29 October 1998 / Accepted: 18 June 1999 相似文献
5.
M. E. Lutcavage R. W. Brill G. B. Skomal B. C. Chase J. L. Goldstein J. Tutein 《Marine Biology》2000,137(2):347-358
Ultrasonic, depth-sensitive transmitters were used to track the horizontal and vertical movements, for up to 48 h, of 11
adult (136 to 340 kg estimated body mass) North Atlantic bluefin tuna (Thunnus thynnus Linnaeus). Fish were tracked in October 1995, September and October 1996, and August and September 1997 in the Gulf of Maine,
northwestern Atlantic. The objective was to document the behavior of these fish and their schools in order to provide the
spatial, temporal, and environmental information required for direct (i.e. fishery-independent) assessment of adult bluefin
tuna abundance using aerial surveys. Transmitters were attached to free-swimming fish using a harpoon attachment technique,
and all fish remained within the Gulf of Maine while being followed. Most of the bluefin tuna tagged on Stellwagen Bank or
in Cape Cod Bay (and followed for at least 30 h) held a predominately easterly course with net horizontal displacements of
up to 76 km d−1. Mean (±SD) swimming depth for all fish was 14 ± 4.7 m and maximum depth for individuals ranged from 22 to 215 m. All but
one fish made their deepest excursions, often single descents, at dawn and dusk. In general, adult bluefin tuna spent <8%
of their time at the surface (0 to 1 m), <19% in the top 4 m, but >90% in the uppermost 30 m. Mean (±SD) speed over ground
was 5.9 km h−1, but for brief periods surpassed 20 to 31 km h−1. Sea surface temperatures during tracking were 11.5 to 22.0 °C, and minimum temperatures encountered by the fish ranged from
6.0 to 9.0 °C. Tagged bluefin tuna and their schools frequented ocean fronts marked by mixed vertebrate feeding assemblages,
which included sea birds, baleen whales, basking sharks, and other bluefin schools.
Received: 19 July 1999 / Accepted: 25 March 2000 相似文献
6.
Thirty-eight yellowfin tuna (Thunnus albacares) were tagged with coded ultrasonic beacons between 6 March and 4 December 1996 near two buoys off the western coast of Oahu,
Hawaii. Two to four tuna were captured, tagged, and released on the same day in as rapid succession as possible in an effort
to tag members of the same school. Automated “listening” monitors attached to the buoys recorded when these marked individuals
entered within a radius of ≤1.1 km of the buoys during a 13 mo period. Twenty-seven of the tuna returned to the site of tagging.
The mean number of returns was 4.2 per tuna (max. = 17), and visits ranged from 1 to 910 min (median = 2.7 min, mean = 40.1 min).
The intervals between successive returns varied from 1 to 257 d (median = 3.0 d, mean = 17.4 d). Seventy-three percent of
the tuna returned together with tunas tagged on the same day, exceeding the frequency of returns of tuna tagged on another
day or arriving alone. This social cohesion is supported by the pattern of return visits by five tuna tagged on 6 March at
Monitoring Station R. Two or more of these tuna arrived together on 24 of 35 d when tagged tuna were detected. All five individuals
visited R on 11 April, a month after tagging, three arrived together 5 mo later on 4 August, and three returned 6 mo later
on 1 December 1996. Tuna often arrived at the same time of day, e.g. Individuals 1 and 3 visited R at 09:15 hrs on 12 April
and at 09:00 hrs 8 mo later. The returns were also site-specific. The 22 tuna tagged at R made 182 return visits to R (92.4%)
and only 15 visits to Monitoring Station K (7.6%), 10 km away. An allegiance of tuna to one school, a predilection for returning
to the site of tagging, and precise timing when visiting sites, are consistent with tuna having migratory pathways consisting
of “way-points” that are visited with temporal regularity.
Received: 30 April 1998 / Accepted: 27 October 1998 相似文献
7.
The population dynamics of zooxanthellae living in the mantle of a giant clam, Tridacna derasa, was studied. The giant clams with shell lengths of 5 to 6 cm which had been reared in the Palau Mariculture Demonstration
Center, in the Republic of Palau, were transferred to aquaria on deck of the R.V. “Sohgen-maru” and kept in running sea water
at 29 to 30 °C. Two clams were removed from the aquaria, and zooxanthellae in the mantle were isolated every 2 h for 24 h.
Numbers of the zooxanthellae in or not in the cell division stage were counted for calculations of the zooxanthellae population
in the mantle and their mitotic index (MI). The MI increased after sunset and reached the maximum values of 6.1 to 11.5% at
03:00 to 05:00 hrs. The specific growth rate, μ, estimated from the MI was 0.083 to 0.14 d−1. Five clams were kept in each of 2 Plexiglas containers in the aquarium for collection of the discharged feces every 3 to
4 h. The discharged zooxanthellae in the feces were counted. The zooxanthellae discharged in 24 h were 0.38 to 1.46% of the
total zooxanthella population in the mantle, and 2.7 to 16.9% of the newly formed zooxanthella population in a day. Increase
of zooxanthella population in the mantle was estimated from clam shell growth rate and from the correlation between zooxanthella
population and clam shell size. Daily increase of zooxanthella population in the mantle was estimated to be approximately
7.6 to 19% of the newly formed zooxanthella population. Therefore, the sum of zooxanthellae populations accounting for daily
increase in the mantle and discharge in the feces was 11 to 36% of the newly formed population. About 64 to 89% of the newly
formed cells were missing; some of these may have been digested by the clam.
Received: 14 July 1996 / Accepted: 19 August 1996 相似文献
8.
Rachel L. Welicky Karen L. Cheney Ann Marie Coile Amber McCammon Paul C. Sikkel 《Marine Biology》2013,160(7):1607-1617
Gnathiid isopod larvae are members of the marine demersal zooplankton community and are common ectoparasites of coral reef fishes, emerging from the substratum, mostly at night and crepuscular periods to feed on fish blood. Given that the activity of many marine organisms is often linked to changes in the phase of the moon, we examined the relationship between lunar phase and activity in gnathiid isopods on Caribbean reefs. We employed two sampling methods to quantify gnathiid activity: (1) Emergence traps set on reefs over a 24 h period; and (2) live fish placed in cages on reefs and retrieved during night and dawn peaks in gnathiid activity. These were compared during discrete phases as well as a continuous metric, the lunar “angle”, and an estimate of ambient light availability (luminance). Lunar phase and angle varied in their statistical effect on gnathiid activity patterns by sampling method and/or year. Luminance had a significant but inconsistent effect on measures of gnathiid activity. Our results suggest that changes in the lunar cycle are not a strong predictor of gnathiid activity at our shallow reef study sites. 相似文献
9.
M. J. Kingsford 《Marine Biology》2001,138(4):853-867
Most presettlement reef fish settled at night at One Tree Island, Great Barrier Reef. Fish were sampled day and night using
channel nets located on the reef crest, and a plankton-mesh purse-seine net in the lagoon (1992–1994). Catches of fish at
night were generally tens to hundreds of times greater than those taken during the day. Preflexion fish, as well as postflexion
and pelagic juveniles, were taken in greater numbers at night. Preflexion forms were a combination of those that had hatched
from demersal eggs and later stages that had been transported over the reef crest. Highest numbers of postflexion and pelagic
juvenile forms of Apogonidae, Blenniidae, Gobiesocidae, Gobiidae, Labridae, Lutjanidae, Mugiloididae, Mullidae, Pomacentridae,
Scaridae, Serranidae and Tripterygiidae were found at night. Observations, while SCUBA diving, and purse-seine samples in
the lagoon indicated that the only resident larvae were of the genera Spratelloides and Hypoatherina; most of the fishes caught in nets, therefore, were immigrants. Patch reefs, sampled for new settlers early in the morning
and late in the day, indicated that the majority of apogonids (Apogon doederleini, >95%) settled at night. Although greater numbers of pomacentrids were found in morning counts (e.g. Pomacentrus wardi), if data were converted to an hourly rate, many pomacentrids showed a similar hourly rate of settlement day and night. Depth-stratified
sampling in waters near One Tree Island (to 20 m) indicated that some taxa rise to the surface at night. This behaviour, perhaps
combined with avoidance of diurnal predators may explain on-reef movement of potential settlers soon after dark. Studies on
settlement cues, therefore, need to focus on night-related phenomena.
Received: 3 March 2000 / Accepted: 20 June 2000 相似文献
10.
The spatial, diel and tidal variability in the abundance of piscivorous fishes and their teleost prey, and the dietary composition
of predatory fishes were investigated in beds of Heterozostera tasmanica within Port Phillip Bay, Australia, from September 1997 to February 1998. Predatory and prey fish assemblages were sampled
from beds of H. tasmanica at three locations during each combination of diel (day and night) and tidal (high and low) cycles. Pelagic and benthic crustaceans
represented >60% by abundance of the diets of all predatory fishes. Seven species, 54% of all predatory fishes, were piscivorous.
These piscivores consumed individuals from seven families, 36.8% of the fish families being associated with seagrass. Western
Australian salmon, Arripis truttacea (Arripidae) (n = 174) and yank flathead, Platycephalus speculator (Platycephalidae) (n = 46) were the most abundant piscivores. A. truttacea consumed larval/post-larval atherinids, gobiids and sillaginids. P. speculator consumed late-juvenile/adult atherinids, clinids and gobiids. While the abundances of piscivores varied between locations
(P < 0.001) and diel periods (P = 0.028), the relative differences in piscivore abundance between sites and diel periods were not consistent between tides.
The abundances of A. truttacea varied in a complex way amongst sites, diel period and tidal cycle, as shown by a three-way interaction between these factors
(P = 0.026). Only during diurnal periods at St. Leonards was the abundance of A. truttacea significantly higher during high than low tides (P < 0.001). During the other diel periods at each site, the abundance of A. truttacea did not vary. P. speculator was significantly more abundant nocturnally (P = 0.017). The abundance of small (prey) fishes varied significantly amongst sites (P < 0.001). During the day, the abundance of small fishes did not vary between high and low tides (P = 0.185), but their nocturnal abundance was greater during low tide (P < 0.001). Atherinids (n = 1732) and sillaginids (n = 1623) were the most abundant families of small fishes. Atherinids were significantly more abundant nocturnally (P = 0.005) and during low tides (P = 0.029), and varied significantly amongst sites (P < 0.001). Sillaginids varied significantly only amongst sites (P < 0.001). Seagrass beds provide a foraging habitat for a diverse assemblage of predatory fishes, many of which are piscivorous.
Anti-predator behaviour and amongst-location variability in abundances of piscivorous fishes may explain some of the diel
and tidal, and broad-scale spatial patterns in small-fish abundances.
Received: 23 July 1999 / Accepted: 18 January 2000 相似文献
11.
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
12.
The genetic relationships among South-East Asian populations of the scad mackerels Decapterus macarellus, D. macrosoma and D. russelli (Pisces: Carangidae) were investigated. In 1995 and 1996, 216 fish were sampled in seven localities spanning the seas of
Indonesia and were examined for restriction-site polymorphisms using ten restriction enzymes for the mitochondrial (mt) DNA
control region, amplified by the polymerase chain-reaction. The inferred phylogeny of haplotypes led to the recognition of
three distinct mitochondrial lineages or phylads consistent with the distinctions of current taxonomy. All 15 mtDNA haplotypes
found in D. macarellus and all 9 haplotypes found in D. macrosoma were arranged as star-like clusters, suggesting recent evolutionary history. In contrast, the phylad formed by 6 haplotypes
in D. russelli from the Sulawesi Sea exhibited diffuse topology, suggesting that ancestral lineages of this species have been retained to
the present. Average nucleotide-divergence estimates between haplotypes of different phylads were between 0.042 and 0.135,
suggesting ancient separation, in consistency with published allozyme data. High levels of haplotype diversity, but no geographical
heterogeneity, was detected within D. macarellus from the Molucca Sea and the Banda Sea. Populations of D. macrosoma exhibited both significant differences between adjacent regions (Sunda Strait and Java Sea), and broadscale genetic homogeneity
from the South China Sea to the Sulawesi Sea via the Java Sea and Makassar Strait. The geographic isolation of the D. macrosoma population sampled in the Sunda Strait suggests that this region constitute a sharp transition zone between the Indian Ocean
and the Sunda Shelf. Near-monomorphism of haplotypes and low nucleotide diversity (d
X) were observed in the samples of D. macrosoma from the continental shelf (haplotype-diversity estimates, h, = 0.00 to 0.25 ± 0.08 and d
X = 0.000 to 0.002). This was in contrast to the comparatively high haplotype and nucleotide diversities observed in other
pelagic fish species including D. macarellus (h = 0.82 ± 0.05, d
X = 0.012 to 0.015) and D. russelli (h = 0.63 ± 0.12, d
X = 0.016), and in the oceanic D. macrosoma population sampled in the Sunda Strait (h = 0.67 ± 0.31, d
X = 0.005). We hypothesise that this may be the consequence of recent and perhaps repeated bottleneck events that have affected
the D. macrosoma population sampled on the continental shelf.
Received: 29 September 1997 / Accepted: 3 September 1999 相似文献
13.
Acoustic telemetry was used to examine patterns of activity and space utilisation of coelacanths, nocturnal predators which
spend the day in submarine caves. Nine coelacanths (Latimeria chalumnae) were tracked, each for a period of 1 to 16 nights at Grande Comore, West Indian Ocean. Activities lasted on average 9 h,
usually starting shortly after sunset and ending before sunrise. Vertically, coelacanths moved up and down at and below cave
level by following the bottom contour, mainly between 180 and 400 m depth. The deepest record was 698 m, the shallowest 133 m.
Most time was spent between 200 and 300 m depth. Large individuals performed deep excursions to depths below 400 m, usually
once per night. The fish spent most time in water temperatures of 15 to 19 °C; they rarely ventured into waters warmer than
22 °C measured at depths shallower than 160 m depth. Horizontally, coelacanths stayed in narrow areas ranging from <1 to 10 km
of coastline. Coelacanths are extremely slow drift-hunters with an estimated average swimming speed of 3.2 m min−1, often travelling not more than 3 km per night. They probably take advantage of local upwelling and downwelling and slow
currents occurring parallel to the steep slopes. This study shows that coelacanths are inhabitants of the subphotic zone,
where they are active mainly below the depth of their daytime refuges.
Received: 7 July 1999 / Accepted: 11 February 2000 相似文献
14.
Movement patterns of large bigeye tuna (Thunnus obesus) in the open ocean, determined using ultrasonic telemetry 总被引:9,自引:0,他引:9
The horizontal and vertical movements of large bigeye tuna (Thunnus obesus Lowe, 1839; 25 to 50 kg) captured in the south Pacific Ocean (French Polynesia) were determined using pressure-sensitive
ultrasonic transmitters. Bigeye tuna swam within the first 100 m below the surface during the night-time and at depths between
400 and 500 m during the daytime. The fish exhibited clear relationships with the sound scattering layer (SSL). They followed
its vertical movements at dawn and dusk, and were probably foraging on the organisms of the SSL. Bigeye tuna did, however,
make regular rapid upward vertical excursions into the warm surface layer, most probably in order to regulate body temperature
and, perhaps, to compensate for an accumulated oxygen debt (i.e. to metabolize lactate). The characteristics of these dives
differ from those reported from previous studies on smaller bigeye tuna (∼12 kg) near the main Hawaiian Islands. During the
daytime, the large fish in French Polynesia made upward excursions approximately only every 2.5 h, whereas smaller fish in
Hawaiian waters made upward excursions approximately every hour. Our data are the first observations on the role of body size
in the vertical behavior of bigeye tuna.
Received: 9 September 1998 / Accepted: 25 November 1999 相似文献
15.
Home range, activity and distribution patterns of a temperate rocky-reef fish, Cheilodactylus fuscus
Red morwong (Cheilodactylus fuscus; Cheilodactylidae: Perciformes), are large temperate rocky reef fish that are patchily distributed in local aggregations
of 3 to >100 fish. The home ranges and aggregating behaviour of red morwong were investigated using external tags (n = 114, over 35 mo) and ultrasonic transmitters (n = 9 over 20 d) at coastal and estuarine sites in south-east Australia. Adult red morwong had a mean home range during the
day of 1865 m2 (SE = 268). Night movement, determined by ultrasonic telemetry, indicated a significantly greater mean home range of 3639 m2 (SE = 416). Home range did not differ significantly with size or sex. Fish movements were greatest and aggregation sizes
varied most during the non-reproductive mid-summer period. Tagged fish (N = 20) displaced 200 to 900 m returned in 1 to 3 d to the point of capture, often traversing open sand habitat and other aggregations.
During the day, fish were commonly found on bouldered habitat. During the night, these site-specific aggregations fragmented
as fish dispersed over a variety of substrata, with crepuscular peaks in activity. Therefore, estimates of habitat-specificity
and feeding patterns collected only by day may give misleading results.
Received: 28 June 1996 / Accepted: 8 July 1998 相似文献
16.
Changes in male guppy courting distance in response to a fluctuating light environment 总被引:1,自引:0,他引:1
In the guppy (Poecilia reticulata), effective courting by a male requires visual contact with the female. Therefore, environmental light intensity may affect
male display behavior, particularly initial courtship distance. We found that male guppies courted at exact and predictable
distances from the female given a particular light level, both in field and laboratory studies. In lower light levels (<0.1 μmol m−2 s−1), for example at dawn, dusk, or under heavy canopy, males court females at closer and less variable distances (<3 cm). At
higher light levels, which occur during most of the day and with less canopy cover, males often court from twice or three
times further out. Light levels over guppy streams change over relatively short time periods and ranges, correlating with
variation in courtship distances. Laboratory manipulations of irradiance confirmed that courtship distance depends on illumination.
Hence, courtship distances may be set by the effect of lighting on signal efficiency, minimization of energy or time expenditures,
or predation risk.
Received: 16 December 1997 / Accepted after revision: 8 August 1998 相似文献
17.
The growth rates of two fish species, the winter flounder Pseudopleuronectes americanus (Walbaum) (19.3 to 42.6 mm total length, TL) and the tautog Tautogaonitis (Linnaeus) (23.9 to 55.9 mm TL), were used to evaluate habitat quality under and around municipal piers in the Hudson River
estuary, USA. Growth rates were measured in a series of 10 d field caging-experiments conducted at two large piers in the
summers of 1996 and 1997. Cages (0.64 m2) were deployed along␣transects that stretched from underneath the piers to beyond them, encompassing the pier edge (the transitional
zone between the pier interior and the outside). Growth in weight (G
w
) was determined at five locations along the transect, 40 m beneath the pier, 20 m beneath the pier, at the pier edge, 20 m
beyond the pier edge, and 40 m beyond. Under piers, mean growth rates of winter flounder and tautogs were negative (xˉG
W
= −0.02 d−1), and rates were comparable to laboratory-starved control fishes (xˉG
W
= −0.02 d−1). In contrast, mean growth rates at pier edges and in open waters beyond piers were generally positive (xˉG
W
ranged from −0.001 to +0.05 d−1), with growth at pier edges often being more variable and less rapid than at open-water sites. Analyses of stomach contents
upon retrieval of caged fishes revealed that dry weights of food were generally higher among fishes caged at open-water stations
(xˉ range = 0.02 to 0.72 mg dry wt) than at pier-edge (xˉ range = 0.01 to 0.54 mg) or under-pier (xˉ range = 0.03 to 0.11 mg) stations, although it was apparent that benthic prey were available at all stations on the transect.
Our results indicate poor feeding conditions among fishes caged under piers, and suboptimal foraging among fishes caged at
pier edges. Inadequate growth rates can lead to higher rates of mortality, and, based on these and other earlier experiments,
we conclude that under-pier environments are poor-quality habitats for some species of juvenile fishes.
Received: 12 March 1998 / Accepted: 9 November 1998 相似文献
18.
K. A. Tricklebank 《Marine Biology》2000,136(2):337-348
Parma microlepis (Günther) were collected from Malabar, an urban location close to the centre of Sydney, Australia, and from Jervis Bay, a
reference location 170 km south of the city centre. At each location, fish were collected from two sites separated by 100
to 200 m. The ultrastructure of normal liver tissue is described based on 20 female fish collected from Jervis Bay, where
fish are known to be exposed to low levels of organochlorine contaminants. Alterations in the endoplasmic reticulum, mitochondria,
lysosomes and nuclei of hepatocytes were identified and quantified in the liver tissue of fish from this location and compared
to alterations in 20 female fish collected from Malabar, where fish are exposed to higher concentrations of organochlorine
pesticides such as DDT compounds. There were significant differences in the percentage of hepatocytes with swollen mitochondria
(F = 124.025, df = 2, 2, P = 0.008) and atypical nuclei (F = 22.198, df = 2, 2, P = 0.043) between sites (100 to 200 m apart), but there were no clear differences between the percentage of structural alterations
in the hepatocytes of P. microlepis from Jervis Bay and Malabar. Associations between liver morphology and the organochlorines aldrin, dieldrin, DDE and chlordane
were examined using a Pearson correlation matrix. Significant correlations were detected between the percentage of hepatocytes
with dilated endoplasmic reticulum and the concentrations of the pesticide aldrin (r = 0.600, df = 11, r
crit(α = 0.05) = 0.553). Significant associations were also detected between the percentage of hepatocytes with disorganised endoplasmic
reticulum and the concentrations of dieldrin and DDE residues in fish (r = 0.576, r = 0.567, respectively, df = 13, r
crit (α = 0.05) = 0.514). However, there was little evidence that ultrastructural alterations in fish responded to increasing concentrations
of these pesticides in a consistent dose-response manner.
Received: 20 October 1998 / Accepted: 24 November 1999 相似文献
19.
Characteristics of the diurnal rhythm of the bioluminescence field are analyzed on the basis of experimental data obtained
in the region around Kamchatka peninsula (50°31′N; 163°50′E). The feasibility of reconstructing the nocturnal structure of
the bioluminescence field by measurements made at other times of the day has been demonstrated. Diurnal rhythm parameters
for the bioluminescent field of several other studied areas of the ocean have been defined. The temporal parameters feature
linear latitudinal dependence. At the equator the boundaries of morning and evening transition periods are 05:06 to 07:30
and 17:48 to 19:54 hrs, respectively. In the Barents Sea in spring these boundaries are 02:42 to 04:06 and 19:48 to 21:12 hrs.
Boundary times of diurnal rhythm do not deviate from the linear regression by more than 10%.
Received: 21 August 1998 / Accepted 4 March 1999 相似文献