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991.
Seung?Hyeon?Kim Young?Kyun?Kim Sang?Rul?Park Wen-Tao?Li Kun-Seop?LeeEmail author 《Marine Biology》2012,159(2):255-267
Seagrass species in the genus Halophila are usually distributed in tropical or subtropical areas, but a Halophila species identified as H. nipponica was first observed in temperate coastal regions of Korea in 2007. Since this species mainly occurs in warm temperate regions
influenced by warm currents, we hypothesized that H. nipponica may exhibit different growth patterns from those of other temperate seagrass species in Korea, instead showing similar growth
dynamics to tropical/subtropical species. The growth and morphology of H. nipponica in relation to coincident measurements of environmental factors were investigated from July 2008 to September 2009 to examine
the growth dynamics of this species. Water temperature at the study site ranged from 9.7°C in January to 25.1°C in August.
Shoot density, biomass, and productivity exhibited significant seasonal variation, increasing during summer and decreasing
during winter. Productivity was severely restricted to nearly ceasing at water temperatures less than 15°C, and winter minimum
growth lasted until May. The optimal temperature for H. nipponica growth was approximately 25°C, which was the maximum water temperature at the study site, and no growth reduction in high
summer water temperature was observed. Thus, H. nipponica on the temperate coast of Korea exhibited a distinctly different growth pattern from those of temperate seagrass species
in Korea, which have shown great reductions in growth at water temperatures higher than 20°C. Higher below- to above-ground
ratio and leaf burial into sediments with shorter leaf petioles during winter might be overwintering strategies in this species.
The growth patterns of H. nipponica at the study site imply that this species still possess the tropical characteristics of the genus Halophila. 相似文献
992.
This study developed an objective quantitative method for detecting small-scale temporal or spatial differences in gametogenesis
in echinoderms. The method was applied to conventional monthly samples of the planktotrophic brittle star, Ophiopholis aculeata, collected at a single site in Newfoundland (eastern Canada) at 10–15 m depth. The samples were analysed to determine gonad
index, oocyte size and gonadal stage using histology. The maturity stage index (MSI) was developed to integrate a measure
of brittle star size (disc diameter), oocyte size and oocyte density. The MSIs ranged from 0 to 800 and had significantly
different means among the four gametogenic stages (early growth, growth, mature and spent). The MSI was more sensitive in
revealing significant differences between consecutive stages than any of its individual constituents. The MSI was also applied
to gametogenic data from the lecithotrophic holothuroid, Mesothuria lactea, again revealing significant differences between successive oogenic stages. This method is expected to be useful in field
and experimental studies of gametogenesis in echinoderms (and possibly other taxa), where it is important to detect not just
the timing of annual peaks in reproduction but small differences in reproductive status among individuals or populations (e.g.
from different habitats or feeding regimes). 相似文献
993.
M.?KoskiEmail author L.?Yebra J.?Dutz S.?H.?J?nasd?ttir C.?Vidoudez H.?H.?Jakobsen G.?Pohnert J.?C.?Nejstgaard 《Marine Biology》2012,159(3):643-660
We studied the effect of a developing Skeletonema marinoi/Phaeocystis spp. bloom on Calanus finmarchicus hatching success, early naupliar survival and metabolism. Our focus was (1) on the development of reproductive rates during
a bloom initiation, peak and decline in relation to the production of potentially toxic algal metabolites and (2) on the proportional
importance of female nutrition versus naupliar food environment for the production of viable nauplii. Despite polyunsaturated
aldehyde (PUA) production by both S. marinoi and Phaeocystis sp., we did not observe any harmful effects on hatching success or naupliar survival and condition in any stages of the short-term
(<1 week) algal bloom. Hatching success appeared to be controlled by egg lipid composition, while the beneficial effect of
a high food concentration was reflected in naupliar RNA:DNA ratio, protein content and total production of viable nauplii.
The egg lipids reflected seston lipids, indicating that the egg fatty acid composition was not modified by the females. Our
results suggest that unselective feeding and/or retention of specific lipids can induce qualitative food limitation, although
recruitment during the S. marinoi/Phaeocystis sp. bloom was high. 相似文献
994.
Sílvia?SantosEmail author Joana?F.?M.?F.?Cardoso Valeska?Borges Rob?Witbaard Pieternella?C.?Luttikhuizen Henk?W.?van der?Veer 《Marine Biology》2012,159(3):601-611
This study analyzed the isotopic profiles of four aragonitic shells of Scrobicularia plana in conjunction with measured seawater temperatures and salinities. Comparison of δ18OSHELL with expected values revealed fractionation of δ18O in near equilibrium with the ambient environment. Growth cessation occurred between November and March. Carbonate deposition
stopped when temperatures were <12°C. Analysis of δ13CSHELL values suggested that carbon in the shell does not reflect the DIC in ambient water, likely due to the incorporation of metabolic
carbon. An ontogenetic trend of increasing δ13C values over time was observed, likely related to changes in metabolic activity. Annual growth patterns were inferred from
δ18OSHELL profiles and compared with internal and external growth lines. Estimations of age based on external lines were unreliable,
resulting in overestimation of age and underestimation of growth rates, likely due to the disturbance lines being wrongly
identified as annual. Analysis of internal lines may lead to over- or underestimation of age and was more reliable in recent
portions of the shell. 相似文献
995.
Alistair?ChealEmail author Michael?Emslie Ian?Miller Hugh?Sweatman 《Marine Biology》2012,159(5):1143-1154
The composition and functionality of ecologically important herbivorous fish assemblages were examined throughout much of
Australia’s Great Barrier Reef (GBR). Diversity and abundance of surgeonfishes (Acanthuridae), parrotfishes (Labridae) and
rabbitfishes (Siganidae) were strongly associated with position on the continental shelf, whilst effects of latitude were
weaker and inconsistent. Species distributions varied considerably amongst taxonomic groups; parrotfishes were mostly widespread
whilst distributions of surgeonfishes were often restricted. Most inshore environments supported depauperate herbivore assemblages
dominated by different taxa and functional groups compared with assemblages in offshore environments. There were also strong
cross-shelf transitions in the main taxa performing each functional role. Overall, this study show that the functional contributions
of herbivorous fish assemblages to important ecosystem processes and the contributing taxa vary considerably amongst different
GBR environments. Additionally, the two most numerically dominant herbivores actively select detritus, not algae, supporting
increasing evidence for the importance of detritus in coral reef ecology. 相似文献
996.
The orange roughy Hoplostethus atlanticus is a well-known commercial species with a global distribution. There is no consensus about levels of connectivity among populations
despite a range of techniques having been applied. We used cytochrome c oxidase subunit I (COI) and cytochrome b sequences to study genetic connectivity at a global scale. Pairwise ΦST analyses revealed a lack of significant differentiation among samples from New Zealand, Australia, Namibia, and Chile. However,
low but significant differentiation (ΦST = 0.02–0.13, P < 0.05) was found between two Northeast Atlantic sites and all the other sites with COI. AMOVA and the haplotype genealogy
confirmed these results. The prevalent lack of genetic differentiation is probably due to active adult dispersal under the
stepping-stone model. Demographic analyses suggested the occurrence of two expansion events during the Pleistocene period. 相似文献
997.
Sebastian?LeuzingerEmail author Bette?L.?Willis Kenneth?R.?N.?Anthony 《Marine Biology》2012,159(1):177-186
An organism’s pattern of resource allocation to reproduction and growth over time critically impacts on its lifetime reproductive
success. During times of low resource availability, there are two fundamental, mutually exclusive strategies of energy investment:
maintenance of somatic tissues to support survival and later reproduction or investment into an immediate reproductive event
at the risk of subsequent death. Here, we examine energy allocation patterns in the coral Montipora digitata to determine whether energy investment during periods of resource shortage favours growth or reproduction in a sessile, modular
marine species. We manipulated light regimes (two levels of shading) on plots within a shallow reef flat habitat (Orpheus
Island, Great Barrier Reef, Australia) and quantified energy uptake (rates of net photosynthesis), energy investment into
reproduction (E
R
), tissue growth per unit surface area (E
T
) and energy channelled into calcification (E
C
). With declining resource availability (i.e. reduced photosynthesis), relative energy investment shifted from high (~80%)
allocation to tissue growth (E
R
:E
T
:E
C
= 11:81:8%) to an increasing proportion channelled into reproduction and skeletal growth (20:31:49%). At the lowest light
regime, calcification was maintained but reproduction was halted and thus energy content per unit surface area of tissue declined,
although no mortality was observed. The changing hierarchy in energy allocation among life functions with increasing resource
limitation found here for an autotrophic coral, culminating in cessation of reproduction when limitations are severe, stands
in contrast to observations from annual plants. However, the strategy may be optimal for maximising fitness components (growth,
reproduction and survival) through time in marine modular animals. 相似文献
998.
The amount of food and when it is available affect both the timing of reproduction and the number of gametes produced by purple
sea urchins, Strongylocentrotus purpuratus. To investigate this further, the effects of food availability on feeding rates, gonad growth, and gamete development were
examined in S. purpuratus collected from the Point Loma kelp forest near San Diego, California, USA (32.69° N, 117.26° W) in September (Fall) 2007,
and February (Spring) and July (Summer) 2008, using laboratory mesocosms. Each seasonal laboratory feeding experiment lasted
3 months, and different levels of food availability were established with different feeding frequencies (from 1 to 7 days
week−1). Gonad tissues of male and female urchins were staged at the end of each experiment using histological analyses. Reduced
food availability resulted in increased daily consumption rates, especially in the Fall when gamete development began. Food
limitation at this time resulted in failure to produce viable gametes, suggesting there is a critical period early in gonad
development when food limitation affects reproductive competency. Food limitation later in gonad development did not stop
viable gamete production, although it did reduce gamete output. 相似文献
999.
József Vuts Till Tolasch Lorenzo Furlan éva Bálintné Csonka Tamás Felf?ldi Károly Márialigeti Teodora B. Toshova Mitko Subchev Amália Xavier Miklós Tóth 《Chemoecology》2012,22(1):23-28
The presence of geranyl octanoate, previously found in pheromone gland extracts of Agriotes lineatus females, was also demonstrated in gland extracts of A. proximus females. Similar to A. lineatus, geranyl butanoate was present only in trace amounts in A. proximus female gland extracts. In air entrainment samples of female A. lineatus and A. proximus beetles, the relative ratio of geranyl butanoate and geranyl octanoate was higher than that in gland extracts. In addition,
comparison of a segment of the mitochondrial cytochrome c oxidase subunit I gene of feral specimens of A. lineatus and A. proximus showed >99% similarity. Both pheromone profile and nucleotide sequence analysis delineate close relationship between the
investigated taxa and postulate taxonomic revision. Further studies on sympatric populations of A. lineatus and A. proximus are underway to investigate and better understand possible processes of species diversification. 相似文献
1000.
Korpinen L P??kk?nen R Gobba F 《International journal of occupational safety and ergonomics》2012,18(2):137-147
The aim of our work was to study the physical symptoms of upper- and lower-level white-collar workers using a questionnaire. The study was cross-sectional with a questionnaire posted to 15 000 working-age persons. The responses (6121) included 970 upper- and 1150 lower-level white-collar workers. In the upper- and lower-level white-collar worker groups, 45.7 and 56.0%, respectively, had experienced pain, numbness and aches in the neck either pretty often or more frequently. When comparing daily computer users and nonusers, there were significant differences in pain, numbness and aches in the neck or in the shoulders. In addition, age and gender influenced some physical symptoms. In the future, it is essential to take into account that working with computers can be especially associated with physical symptoms in the neck and in the shoulders when workers use computers daily. 相似文献