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1.
Recruitment and population structure of Perna perna in low shore mussel beds were investigated over 15 months at six sites along the south coast of South Africa. Initial, subjective
classification of sites as wave exposed or wave sheltered (three of each) was confirmed using the dissolution of cement blocks
to measure average water flux and dynamometers for maximum wave force. Recruitment occurred throughout the year, but recruit
(1–5 mm) densities were significantly higher from January to April 1996 on both shore types. Recruit densities were positively
correlated with adult (>15 mm) densities for both shore types (P < 0.05) but the correlations were extremely weak (r
2 < 0.06 in each case). In areas with 100% cover, adult size (mean and maximum lengths) was greater on exposed sites, but density
showed the reverse and was negatively correlated with maximum wave strength (r = −0.84). Despite differences in adult densities and sizes, biomass, which is a product of the two, showed no significant
difference between the two shore types (ANOVA P > 0.05). Thus wave exposure dramatically affects density, recruitment and mussel size, but not recruitment timing or biomass
where there is 100% cover, and mediates a three-way interaction among food supply, larval supply and intraspecific competition
for space. In contrast to shores with saturation recruitment, mussel biomass here appears to be limited by recruit supply
and constraints of food, especially on sheltered shores, while density is regulated through intraspecific competition for
space primarily on exposed shores and at small spatial scales. 相似文献
2.
Hypoxia due to the over enrichment of waters by nutrients is becoming a global problem. In mussels, enhanced byssus thread
production is an important adaptation to the presence of crustacean predators and to energetic hydrodynamic regimes. Thread
production is an energy-consuming process, so this study used the green mussel Perna
viridis (L.) to examine the response to predator exposure combined with hypoxia. Hypoxia is common in sheltered bays in Hong Kong,
and the mussels were collected in one such bay, Lok Wo Sha (latitude/longitude: 22o18′ N/114o10′ E) in January, 2009. The
predator used in the experiments was the swimming crab Thalamita danae. Oxygen concentrations used in the 48-h experiments ranged from hypoxic to normoxic (1.5 ± 0.3 mg l−1, 3.0 ± 0.3 mg l−1 and 6.0 ± 0.3 mg l−1). Fewer byssus threads which were also shorter and thinner were produced at reduced oxygen levels, no matter if the predator
was present or not; the frequency the mussels shed stalks was also lower. Mussels exposed to the predator, however, have enhanced
byssus thread production at all oxygen levels when compared with the control. This has highlighted the significance of anti-predator
responses for the survival of individuals even under a stressful environment in which energy supply is limited by aerobic
metabolism. Interactive effects between oxygen level and predator exposure were observed for the byssus thread production
(frequency of shed stalks, mean byssus thread length, cumulative byssus thread volume), with values obtained at 1.5 and 3.0 mg
O2 l−1 being statistically indistinguishable for the control group without predator but not for the predator group. The lack of
differences in the byssus thread production at lower oxygen levels in the absence of predator may indicate the minimum amount
of byssus that is required for settlement on a substrate. 相似文献
3.
In this study, juvenile colonies of massive Porites spp. (a combination of P. lutea and P. lobata) from the lagoon of Moorea (W 149°50′, S 17°30′) were damaged and exposed to contrasting conditions of temperature and flow
to evaluate how damage and abiotic conditions interact to affect growth, physiological performance, and recovery. The experiment
was conducted in April and May 2008 and consisted of two treatments in which corals were either undamaged (controls) or damaged
through gouging of tissue and skeleton in a discrete spot mimicking the effects of corallivorous fishes that utilize an excavating
feeding mode. The two groups of corals were incubated for 10 days in microcosms that crossed levels of temperature (26.7 and
29.6°C) and flow (6 and 21 cm s−1), and the response assessed as overall colony growth (change in weight), dark-adapted quantum yield of PSII (F
v/F
m), and healing of the gouged areas. The influence of damage on growth was affected by temperature, but not by flow. When averaged
across flow treatments, damage promoted growth by 25% at 26.7°C, but caused a 25% inhibition at 29.6°C. The damage also affected
F
v/F
m in a pattern that differed between flow speeds, with a 10% reduction at 6 cm s−1, but a 4% increase at 21 cm s−1. Regardless of damage, F
v/F
m at 21 cm s−1 was 11% lower at 26.7°C than at 29.6°C, but was unaffected by temperature at 6 cm s−1. The lesions declined in area at similar rates (4–5% day−1) under all conditions, although the tissue within them regained a normal appearance most rapidly at 26.7°C and 6 cm s−1. These findings show that the response of poritid corals to sub-lethal damage is dependent partly on abiotic conditions,
and they are consistent with the hypothesis that following damage, calcification and photosynthesis can compete for metabolites
necessary for repair, with the outcome affected by flow-mediated mass transfer. These results may shed light upon the ways
in which poritid corals respond to biting by certain corallivorous fishes. 相似文献
4.
We have analyzed the composition, diversity, density and biomass of a temporal series of samples taken in a Tubularia indivisa community, which dominates a shipwreck in the North Sea waters (N 51°23′,730–E 02°29′,790, 17 nautical miles from the coast,
30 m depth). This shipwreck has structures emerging up to 8 m above the seabed. Water temperature ranged from 4.2°C in March
to 20.3°C in August. Salinity showed few variations around 33.9 psu. Bottom tidal currents followed a semi-diurnal cycle and
were preferentially NE oriented with 84% of them in the range 0.25–0.75 m s−1. The mean value for total suspended matter was 6.2 mg l−1 with large variations on a monthly scale. The species richness of samples varied from 15 in October to 42 in August with
a mean value of 33 species. Diversity indices were higher during autumn and winter because of the strong dominance of a few
crustacean species during the warmer months. The total density of individuals ranged from 6,500 ind m−2 in October to 445,800 ind m−2 in July, most of these individuals belonging to the amphipod species Jassa herdmani. The biomass of the T. indivisa community varied from 9 g AFDW m−2 in October to 1,106 g AFDW m−2 in July, with T. indivisa itself constituting between 59 and 82% of the total biomass. The biomass of T. indivisa was positively correlated with species richness and with the density of 23% of the species identified on this community,
suggesting that T. indivisa plays an important structural role in this habitat. This was further confirmed by the number of species associated with T. indivisa which was generally superior to 55% of the sorted species. Multivariate analysis indicated strong differences between spring/summer−autumn/winter
assemblages mostly but not solely due to the abundance patterns of species. These findings support the conclusion that shipwrecks
in Belgian waters allow the development of assemblages dominated by a high biomass of T. indivisa which in turn provides shelter for high densities and biomass of epizoites. These assemblages will further show large monthly
variations in densities and composition due to large variation in T. indivisa biomass under an apparent repetitive annual cycle.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Michael D. Arendt Albert L. Segars Julia I. Byrd Jessica Boynton Jeffrey A. Schwenter J. David Whitaker Lindsey Parker 《Marine Biology》2012,159(1):113-125
Sixteen satellite-tagged adult male loggerhead sea turtles (Caretta caretta) dispersed widely from an aggregation near Port Canaveral, Florida, USA (28°23′N, −80°32′W) after breeding. Northbound males
migrated further (990 ± 303 km) than southbound males (577 ± 168 km) and transited more rapidly (median initial dive duration = 6
(IQR = 4–16) versus 19 (IQR = 10–31) min, respectively).. Migration occurred along a depth corridor (20–40 m) except where
constricted by a narrow continental shelf width. Males foraged in areas 27 ± 41 km2 day−1 at locations <1–80 km from shore for 100.1 ± 60.6 days, with variability in foraging patterns not explained by turtle size
or geography. Post-breeding dispersal patterns were similar to patterns reported for adult female loggerhead sea turtles in
this region and adult male loggerhead sea turtles elsewhere in the northern hemisphere; however, foraging ground distributions
were most similar to adult female loggerhead sea turtles in this region. 相似文献
6.
At specific locations within the Baltic Sea, thermoclines and haloclines can create rapid spatial and temporal changes in
temperature (T) and salinity (S) exceeding 10°C and 9 psu with seasonal ranges in temperature exceeding 20°C. These wide ranges in abiotic factors affect
the distribution and abundance of Baltic Sea copepods via species-specific, physiological-based impacts on vital rates. In
this laboratory study, we characterized the influence of T and S on aspects of reproductive success and naupliar survival of a southwestern Baltic population of Temora longicornis (Copepoda: Calanoida). First, using ad libitum feeding conditions, we measured egg production (EP, no. of eggs female−1 day−1) at 12 different temperatures between 2.5 and 24°C, observing the highest mean EP at 16.9°C (12 eggs female−1 day−1). Next, the effect of S on EP and hatching success (HS, %) was quantified at 12°C for cohorts that had been acclimated to either 8, 14, 20 or 26 psu
and tested at each of five salinities (8, 14, 20, 26 and 32 psu). The mean EP was highest for (and maximum EP similar among)
14, 20 and 26 psu cohorts when tested at their acclimation salinity whereas EP was lower at other salinities. For adults reared
at 8 psu, a commonly encountered salinity in Baltic surface waters, EP was relatively low at all test salinities—a pattern
indicative of osmotic stress. When incubated at 12°C and 15 different salinities between 0 and 34 psu, HS increased asymptotically
with increasing S and was maximal (82.6–84.3%) between 24 and 26 psu. However, HS did depend upon the adult acclimation salinity. Finally,
the 48-h survival of nauplii hatched and reared at 14 psu at one of six different temperatures (10, 12, 14, 16, 18 and 20°C)
was measured after exposure to a novel salinity (either 7 or 20 psu). Upon exposure to 7 psu, 48-h naupliar mortality increased
with increasing temperature, ranging from 26.7% at 10°C to 63.2% at 20°C. In contrast, after exposure to 20 psu, mortality
was relatively low at all temperatures (1.7% at 10°C and ≤26.7% for all other temperatures). An intra-specific comparison
of EP for three different T. longicornis populations revealed markedly different temperature optima and clearly demonstrated the negative impact of brackish (Baltic)
salinities. Our results provide estimates of reproductive success and early survival of T. longicornis to the wide ranges of temperatures and salinities that will aid ongoing biophysical modeling examining climate impacts on
this species within the Baltic Sea. 相似文献
7.
Helen S. Findlay Michael A. Kendall John I. Spicer Stephen Widdicombe 《Marine Biology》2010,157(4):725-735
Ocean acidification and global warming are occurring concomitantly, yet few studies have investigated how organisms will respond
to increases in both temperature and CO2. Intertidal microcosms were used to examine growth, shell mineralogy and survival of two intertidal barnacle post-larvae,
Semibalanus balanoides and Elminius modestus, at two temperatures (14 and 19°C) and two CO2 concentrations (380 and 1,000 ppm), fed with a mixed diatom-flagellate diet at 15,000 cells ml−1 with flow rate of 10 ml−1 min−1. Control growth rates, using operculum diameter, were 14 ± 8 μm day−1 and 6 ± 2 μm day−1 for S. balanoides and E. modestus, respectively. Subtle, but significant decreases in E. modestus growth rate were observed in high CO2 but there were no impacts on shell calcium content and survival by either elevated temperature or CO2. S. balanoides exhibited no clear alterations in growth rate but did show a large reduction in shell calcium content and survival under
elevated temperature and CO2. These results suggest that a decrease by 0.4 pH(NBS) units alone would not be sufficient to directly impact the survival of barnacles during the first month post-settlement.
However, in conjunction with a 4–5°C increase in temperature, it appears that significant changes to the biology of these
organisms will ensue. 相似文献
8.
Peter J. Edmunds 《Marine Biology》2009,156(9):1797-1808
This study tested the effects of acclimatization on the response of corals to elevated temperature, using juvenile massive
Porites spp. and branching P. irregularis from Moorea (W149°50′, S17°30′). During April and May 2006, corals were acclimatized for 15 days to cool (25.7°C) or ambient
(27.7°C) temperature, under shaded (352 μmol photons m−2 s−1) or ambient (554 μmol photons m−2 s−1) natural light, and then incubated for 7 days at ambient or high temperature (31.1°C), under ambient light (659 μmol photons
m−2 s−1). The response to acclimatization was assessed as biomass, maximum dark-adapted quantum yield of PSII (F
v/F
m), and growth, and the effect of the subsequent treatment was assessed as F
v/F
m and growth. Relative to the controls (i.e., ambient temperature/ambient light), massive Porites spp. responded to acclimatization through increases in biomass under ambient temperature/shade, and low temperature/ambient
light, whereas P. irregularis responded through reduced growth under ambient temperature/shade, and low temperature/ambient light. Acclimatization affected
the response to thermal stress for massive Porites spp. (but not P. irregularis), with an interaction between the acclimatization and subsequent treatments for growth. This interaction resulted from a
lessening of the negative effects of high temperature after acclimatizing to ambient temperature/shade, but an accentuation
of the effect after acclimatizing to low temperature/shade. It is possible that changes in biomass for massive Porites spp. are important in modulating the response to high temperature, with the taxonomic variation in this effect potentially
resulting from differences in morphology. These results demonstrate that corals can acclimatize during short exposures to
downward excursions in temperature and light, which subsequently affects their response to thermal stress. Moreover, even
con-generic taxa differ in this capacity, which could affect coral community structure.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
Serena Caplins Miguel Angel Penna-Diaz Erick Godoy Nelson Valdivia J. M. Turbeville Martin Thiel 《Marine Biology》2012,159(6):1363-1374
Understanding the impact of environmental stressors on predator activity is a prerequisite to understanding the underlying
mechanisms shaping community structure. The nemertean Prosorhochmus nelsoni is a common predator in the mid-intertidal zone on rocky shores along the Chilean coast, where it can reach very high abundances
(up to 260 ind m−2) in algal turfs, algal crusts, barnacle crusts, and mixed substrata. Tidal and diurnal scans revealed that the activity of
P. nelsoni is primarily restricted to night and early-morning low tides and is relatively low when air temperatures are high. On average,
larger worms crawled faster than smaller worms, with their maximum velocity being influenced by substratum type. Their estimated
rate of predation is 0.092 prey items nemertean−1 day−1, just below the laboratory rate of ~0.2 amphipods nemertean−1 day−1 previously estimated for this species. P. nelsoni consumes a diverse spectrum of prey items (i.e., amphipods, isopods, decapods, barnacles, and dipterans) and is possibly
exerting a significant influence on its prey populations. We suggest that the opportunistic predatory behavior of this intertidal
predator is caused by the trade-off between immediate persistence (e.g., avoidance of desiccation) and long-term survival
through successful foraging. 相似文献
10.
Balanus amphitrite, an acorn barnacle, is distinctly euryhaline, eurythermal and a dominant fouling organism found in warm and temperate waters throughout the world. In this study, the influence of temperature and food concentration on the reproductive biology of this species collected from a tropical habitat was evaluated. Adult barnacles were maintained at 20, 25 and 30°C temperatures at different concentrations of food (50, 100, 150 and 200 Artemia ind−1 day−1). In this previously believed obligatory cross-fertilizing hermaphrodite, self-fertilization was observed. The rise in temperature from 20 to 30°C resulted in a longer interbreeding interval (6–7 days, 200 Artemia ind−1 day−1; 11–13 days, 50 Artemia ind−1 day−1). Computed carbon gained through feeding during the interbreeding interval indicated an inverse relationship to the temperature. At 20°C, although a greater amount of carbon was gained through feeding, the numbers of larvae produced were fivefold less when compared to those raised at 30°C. At 20°C, 2.3 μg C was required to produce a single larva, whereas at 30°C it was 0.4 μg C. A rise in rearing temperature also influenced the molting rate positively. Observations on temporal variation in the gonad development of this species in a tropical coastal environment influenced by the monsoons indicated gonad development to be positively related to chlorophyll a concentration. 相似文献
11.
The fate of 100 marked recruits of the rhizophytic alga Halimeda incrassata was followed in Puerto Morelos reef lagoon, Mexican Caribbean (20°52′N, 86°51′W), until death of the last individual from
April 2005–2007. Juvenile mortality was relatively high (19%), the half-life of adult thalli was 13 months and maximal lifespan
was 2 years. First age of sexual reproduction was 10 months, but only 6% of the marked thalli reproduced sexually. A subsequent
static life-table approach (February–April 2008) at two sites indicated low spatial variation in transition probabilities
between the life stages. Recruits were found throughout the year (density 2–11 thalli m−2) and were mostly of clonal origin. In a disturbed area, the density of sexual recruits was ~0.01 thalli m2. Temporal fluctuations in population size depended on mortality rates, which increased slightly after hurricanes Emily (July
2005) and Wilma (October 2005), but might otherwise be regulated by density-dependent processes. 相似文献
12.
A. A. Keller C. Taylor C. Oviatt T. Dorrington G. Holcombe L. Reed 《Marine Biology》2001,138(5):1051-1062
The seasonal productivity cycle and factors controlling annual variation in the timing and magnitude of the winter–spring
bloom were examined for several locations (range: 42°20.35′–42°26.63′N; 70°44.19′–70°56.52′W) in Boston Harbor and Massachusetts
Bay, USA, from 1995 to 1999, and compared with earlier published data (1992–1994). Primary productivity (mg C m−2 day−1) in Massachusetts Bay from 1995 to 1999 was generally characterized by a well-developed winter–spring bloom of several weeks
duration, high but variable production during the summer, and a prominent fall bloom. The bulk of production (mg C m−3 day−1) typically occurred in the upper 15 m of the water column. At a nearby Boston Harbor station a gradual pattern of increasing
areal production from winter through summer was more typical, with the bulk of production restricted to the upper 5 m. Annual
productivity in Massachusetts Bay and Boston Harbor ranged from a low of 160 g C m−2 year−1 to a high of 787 g C m−2 year−1 from 1992 to 1999. Mean annual productivity was higher (mean=525 g C m−2 year−1) and more variable near the harbor entrance than in western Massachusetts Bay. At the harbor station productivity varied
more than 3.5-fold (CV=40%) over an 8 year sampling period. Average annual productivity (305–419 g C m−2 year−1) and variability around the means (CV=25–27%) were lower at both the outer nearfield and central nearfield regions of Massachusetts
Bay. Annual productivity in 1998 was unusually low at all three sites (<220 g C m−2 year−1) due to the absence of a winter–spring phytoplankton bloom. Potential factors influencing the occurrence of a spring bloom
were investigated. Incident irradiance during the winter–spring period was not significantly different (P > 0.05) among years (1995–1999). The mean photic depth during the bloom period was significantly deeper (P < 0.05) in 1998, signifying greater light availability with depth. Nutrients were also in abundance during the winter–spring
of 1998 with stratified conditions not observed until May. In general, the magnitude of the winter–spring bloom in Massachusetts
Bay from 1995 to 1999 was significantly correlated with winter water temperature (r
2=0.78) and zooplankton abundance (r
2=0.74) over the bloom period (typically February–April). The absence of the 1998 bloom was associated with higher than average
water temperature and elevated levels of zooplankton abundance just prior to, and during, the peak winter–spring bloom period.
Received: 3 July 2000 / Accepted: 6 December 2000 相似文献
13.
Peter J. Edmunds 《Marine Biology》2012,159(10):2149-2160
I tested the hypothesis that high pCO2 (76.6 Pa and 87.2 Pa vs. 42.9 Pa) has no effect on the metabolism of juvenile massive Porites spp. after 11 days at 28 °C and 545 μmol quanta m−2 s−1. The response was assessed as aerobic dark respiration, skeletal weight (i.e., calcification), biomass, and chlorophyll fluorescence. Corals were collected from the shallow (3–4 m) back reef of Moorea, French Polynesia (17°28.614′S, 149°48.917′W), and experiments conducted during April and May 2011. An increase in pCO2 to 76.6 Pa had no effect on any dependent variable, but 87.2 Pa pCO2 reduced area-normalized (but not biomass-normalized) respiration 36 %, as well as maximum photochemical efficiency (F v/F m) of open RCIIs and effective photochemical efficiency of RCIIs in actinic light (∆F/); neither biomass, calcification, nor the energy expenditure coincident with calcification (J g−1) was effected. These results do not support the hypothesis that high pCO2 reduces coral calcification through increased metabolic costs and, instead, suggest that high pCO2 causes metabolic depression and photochemical impairment similar to that associated with bleaching. Evidence of a pCO2 threshold between 76.6 and 87.2 Pa for inhibitory effects on respiration and photochemistry deserves further attention as it might signal the presence of unpredictable effects of rising pCO2. 相似文献
14.
15.
The horned sea star (Protoreaster nodosus) is relatively common in the Indo-Pacific region, but there is little information about its biology. This study of the population
biology of P. nodosus was carried out in Davao Gulf, The Philippines (7°5′N, 125°45′E) between September 2006 and May 2008. Protoreaster nodosus was found in sand and seagrass dominated habitats at a mean density of 29 specimens per 100 m2 and a mean biomass of 7.4 kg per 100 m2, whereas a significantly lower density and biomass was found in coral and rock dominated habitats. Adult specimens (mean
radius R = 10.0 cm) were found at depths of 0–37 m, whereas juveniles (R < 8 cm) were only found in shallow sandy habitats with abundant seagrass (water depth ≤2 m). Increased gonad weights were
found from March to May (spawning period), which coincided with an increasing water temperature and a decreasing salinity.
Density and biomass did not change significantly during reproduction, but sea stars avoided intertidal habitats. All specimens
with R > 8 cm had well developed gonads and their sex ratio was 1:1. Protoreaster nodosus grew relatively slowly in an enclosure as described by the exponential function G = 7.433 e−0.257 × R
. Maturing specimens (R = 6–8 cm) were estimated to have an age of 2–3 years. Specimens with a radius of 10 cm (population mean) were calculated
to have an age of 5–6 years, while the maximum age (R = 14 cm) was estimated as 17 years. Potential effects of ornamental collection on the sea star populations are discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
16.
While it is known that Antarctic sea ice biomass and productivity are highly variable over small spatial and temporal scales,
there have been very few measurements from eastern Antarctic. Here we attempt to quantify the biomass and productivity and
relate patterns of variability to sea ice latitude ice thickness and vertical distribution. Sea ice algal biomass in spring
in 2002, 2003 and 2004 was low, in the range 0.01–8.41 mg Chl a m−2, with a mean and standard deviation of 2.08 ± 1.74 mg Chl a m−2 (n = 199). An increased concentration of algae at the bottom of the ice was most pronounced in thicker ice. There was little
evidence to suggest that there was a gradient of biomass distribution with latitude. Maximum in situ production in 2002 was
approximately 2.6 mg C m−2 h−1 with assimilation numbers of 0.73 mg C (mg Chl a)−1 h−1. Assimilation numbers determined by the 14C incubations in 2002 varied between 0.031 and 0.457 mg C (mg Chl a)−1 h−1. Maximum fluorescence quantum yields of the incubated ice samples in 2002 were 0.470 ± 0.041 with E
k indices between 19 and 44 μmol photons m−2 s−1. These findings are consistent with the shade-adapted character of ice algal communities. In 2004 maximum in situ production
was 5.9 mg C m−2 h−1 with an assimilation number of 5.4 mg C (mg Chl a)−1 h−1. Sea ice biomass increased with ice thickness but showed no correlation with latitude or the time the ice was collected.
Forty-four percent of the biomass was located in bottom communities and these were more commonly found in thicker ice. Surface
communities were uncommon. 相似文献
17.
Adults of motile intertidal invertebrates are able to seek shelter to avoid environmental stress associated with low tides,
but embryos within egg masses are effectively sessile for the duration of their encapsulation. Gastropod egg masses from 34
taxa on two rocky shores in SE Australia (34°37′08″S, 150°92′03″E and 34°35′45″S, 150°53′20″E) were surveyed over 2 years
(June 2002–May 2004) to test the hypothesis that eggs are deposited in patterns that minimize exposure to environmental stress.
Egg masses were expected to be predominantly deposited in shaded habitats not prone to environmental extremes. It was also
anticipated that the deposition of egg masses in habitats exposed to UVR, desiccation, and/or extremes in temperature would
occur when exposure to these abiotic factors was minimized. Among the taxa investigated, only four species spawned in full
sun (Bembicium nanum, Nerita morio, Siphonaria zelandica and S. denticulata). Summer had the highest UVR index, water temperature, and air temperature as well as the lowest daytime tides. Univariate
and multivariate analyses confirmed that egg mass abundance was highest during summer, with no change in egg mass size. This
study shows that those species depositing egg masses on the surfaces of rock platforms do not adjust the seasonal timing or
macrohabitat location of their spawning to avoid physiologically stressful conditions, particularly UVR. Alternate reasons
for the evolution of egg mass deposition behavior in apparently sub-optimal habitats are discussed, and it is almost certainly
the complex interplay of a variety of highly species-specific factors that is responsible for the patterns observed. 相似文献
18.
Arthur R. Bos Girley S. Gumanao Marieke M. van Katwijk Benjamin Mueller Marjho M. Saceda Rosie Lynn P. Tejada 《Marine Biology》2011,158(3):639-648
Archaster typicus, a common sea star in Indo-Pacific regions, has been a target for the ornamental trade, even though little is known about
its population biology. Spatial and temporal patterns of abundance and size structure of A. typicus were studied in the Davao Gulf, the Philippines (125°42.7′E, 7°0.6′N), from February 2008 to December 2009. Specimens of
A. typicus were associated with intertidal mangrove prop roots, seagrass meadows, sandy beaches, and shoals. Among prop roots, specimens
were significantly smaller and had highest densities (131 ind. m−2) between November and March. High organic matter in sediment and a relatively low predation rate seemed to support juvenile
life among mangroves. Size and density analyses provided evidence that individuals gradually move to seagrass, sandy habitats,
and shoals as they age. Specimens were significantly larger at a shoal (maximum radius R = 81 mm). New recruits were found between August and November in both 2008 and 2009. Timing of recruitment and population
size frequencies confirmed a seasonal reproductive cycle. Juveniles had relatively high growth rates (2–7 mm month−1) and may reach an R of 20–25 mm after 1 year. Growth rates of larger specimens (R > 30 mm) were generally <2 mm month−1. The activity pattern of A. typicus was related to the tidal phase and not to time of day: Specimens moved over the sediment surface during low tides and were
burrowed during high tides possibly avoiding predation. This is one of the first studies to document an ontogenetic habitat
shift for sea stars and provides new biological information as a basis for management of harvested A. typicus populations. 相似文献
19.
Wai-Lun Chiang Rudolf Shiu-Sun Wu Peter Kwan-Ngok Yu Doris Wai-Ting Au 《Marine Biology》2007,151(2):703-711
Earlier laboratory experiments suggested that environmental levels of UV-B radiation can damage the eyes of barnacle naupliar
larvae and impair their phototactic behaviors. However, since barnacle larvae may avoid UV by migrating to deeper waters,
it is not known whether such impairment would actually occur under field conditions. For the first time, this study provides
both field and laboratory evidences to show that prevailing UV-B in the natural habitat of barnacle larvae could be an important
environmental factor affecting natural barnacle populations. We here showed that although barnacle nauplii may avoid UV-B
irradiation by downward migration, the amount of UV energy (9.8 × 10−6 J) received by a naupliar eye during downward migration in the natural water column is within the same order of magnitude
as the total energy (7.5 × 10−6 J) sufficient to cause damages to naupliar eye and impair their phototactic responses. It is possible that solar UV-B prevailing
at shallow waters would pose a similar threat to other zooplankton species over large geographic scale. 相似文献
20.
Simmons RW Noble AD Pongsakul P Sukreeyapongse O Chinabut N 《Environmental geochemistry and health》2009,31(1):71-79
Research undertaken over the last 40 years has identified the irrefutable relationship between the long-term consumption of
cadmium (Cd)-contaminated rice and human Cd disease. In order to protect public health and livelihood security, the ability
to accurately and rapidly determine spatial Cd contamination is of high priority. During 2001–2004, a General Linear Regression
Model Irr-Cad was developed to predict the spatial distribution of soil Cd in a Cd/Zn co-contaminated cascading irrigated
rice-based system in Mae Sot District, Tak Province, Thailand (Longitude E 98°59′–E 98°63′ and Latitude N 16°67′–16°66′).
The results indicate that Irr-Cad accounted for 98% of the variance in mean Field Order total soil Cd. Preliminary validation
indicated that Irr-Cad ‘predicted’ mean Field Order total soil Cd, was significantly (p < 0.001) correlated (R
2 = 0.92) with ‘observed’ mean Field Order total soil Cd values. Field Order is determined by a given field's proximity to
primary outlets from in-field irrigation channels and subsequent inter-field irrigation flows. This in turn determines Field
Order in Irrigation Sequence (Field OrderIS). Mean Field Order total soil Cd represents the mean total soil Cd (aqua regia-digested) for a given Field OrderIS. In 2004–2005, Irr-Cad was utilized to evaluate the spatial distribution of total soil Cd in a ‘high-risk’ area of Mae Sot
District. Secondary validation on six randomly selected field groups verified that Irr-Cad predicted mean Field Order total
soil Cd and was significantly (p < 0.001) correlated with the observed mean Field Order total soil Cd with R
2 values ranging from 0.89 to 0.97. The practical applicability of Irr-Cad is in its minimal input requirements, namely the
classification of fields in terms of Field OrderIS, strategic sampling of all primary fields and laboratory based determination of total soil Cd (T-CdP) and the use of a weighed coefficient for Cd (CoeffW). The use of primary fields as the basis for Irr-Cad is also an important practical consideration due to their inherent ease
of identification and vital role in the classification of fields in terms of Field OrderIS. The inclusion of mean field order soil pH (1:5water) to the Irr-Cad model accounted for over 79% of the variation in mean Field Order bio-available (DTPA (diethylenetriaminepentaacetic
acid)-extractable) soil Cd. Rice is the staple food of countries of the Greater Mekong Sub-region (includes Vietnam, Myanmar,
Lao PDR, Thailand and Yunnan Province, China). These countries also have actively and historically mined Zn, Pb, and Cu deposits
where Cd is likely to be a potential hazard if un-controlled discharge/runoff enters areas of rice cultivation. As such, it
is envisaged that the Irr-Cad model could be applied for Cd hazard assessment and effectively form the basis of intervention
options and policy decisions to protect public health, livelihoods, and export security. 相似文献