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991.
Daniela Marques Ana I. Esteves Marise Almeida Joana Xavier Madalena Humanes 《Marine Biology》2008,153(5):807-813
The aim of this work is to investigate the activity of the antioxidant enzyme superoxide dismutase in the cosmopolitan sponge
Cliona celata (Grant, 1826), since this enzyme has been described as a useful biomarker for marine pollution in other marine invertebrates.
The quantification of the catalytic activity for superoxide dismutase is quite complex because its substrate is an unstable
free radical. Several methods have been developed for this enzymatic activity determination; most of them are based on inhibition
of a redox reaction involving the superoxide radical. In this work, two methods are compared, for crude sponge extracts, as
far as repeatability, reproducibility and sensibility are concerned. The adrenaline oxidation method seems to be the most
adequate for these determinations. Statistical treatment of the data indicates that the reference value for the specific superoxide
dismutase activity in C. celata should be in the interval [0–535.5] U/mg of total protein in wet tissues, for normal populations. 相似文献
992.
Fiddler crabs, Uca pugnax, were collected from a highly contaminated site and a relatively clean site, both in New Jersey to determine if and how environments
with varying levels of pollutants may impact aspects of population biology including individual size, morphology (major cheliped
size), population density, fecundity, recruitment and survivorship of early benthic phases. Crabs from the highly contaminated
site were significantly larger in size, but had lower population density, lower recruitment, reduced reproductive season and
lower survivorship of early benthic phases. Our study suggests that contamination may play a role in population ecology of
U. pugnax. This study also determined that the reproductive season for U. pugnax in New Jersey is much longer than reported in the literature and could potentially be impacted by global climate change. 相似文献
993.
Although snappers (Lutjanidae) are commercially important fishery resources in tropical and subtropical waters, their home
range size and its spatial arrangement have not been sufficiently clarified. In the present study, the size and spatial arrangement
of the home range of the reef-associated checkered snapper Lutjanus decussatus (Lutjanidae) were investigated by use of a portable GPS receiver. In a 120 m × 120 m quadrat established on a section of
the fringing reef of Ishigaki Island, 29 individuals of the species were identified by their color pattern and individuals
were divided into five arbitrary size classes (class 1 <10 cm TL ≤ class 2 <15 cm TL ≤ class 3 <20 cm TL ≤ class 4 <25 cm
TL ≤ class 5). Fish tracking by snorkeling was conducted with the portable GPS receiver. Site fidelity of this species was
high. Home range size ranged from 93.0 to 3638.4 m2, and there was a significant positive correlation between the home range size and fish total length. Home ranges of the same-sized
individuals abutted each other (8.8% area overlap), whereas those of different-sized individuals overlapped (44.0% area overlap).
Agonistic behavior (attack and agonistic display) was more frequently found among same-sized individuals (times of agonistic
behavior/times of all encounters × 100 = 71.3%), whereas such agonistic behavior was rarely found among different-sized individuals
(times of agonistic behavior/times of all encounters × 100 = 6.9%). These results suggest that home ranges of Lutjanus decussatus can be regarded as territories against same-sized individuals, but not different-sized individuals. The usefulness of the
fish tracking by snorkeling using a portable GPS receiver for home range size estimation and the function of the overlapping
territory of the species are discussed. 相似文献
994.
Among pelagic fish, the Southwestern Atlantic menhaden genus Brevoortia (Clupeidae, Alosinae) constitutes an important species model to investigate the patterns of genetic differentiation. It is
abundant in the Río de la Plata estuary and in the Atlantic coastal lagoons system from Uruguay and Southern Brazil. To access
in the taxa discrimination and population structure in Brevoortia we perform a phylogeographic approach based on mitochondrial cytochrome b (cyt-b) sequences including 240 individuals from 16 collecting sites. Among the 720 bp cyt-b sequenced, 199 correspond to variables and 88 to phylogenetically informative sites. High values of haplotype diversity (h = 1.000) and nucleotide diversity (π = 0.061), as well as an average of 0.084 polymorphic segregating sites and 46 different haplotypes were found. Maximum likelihood
analysis based on the GTR + I + G model and Bayesian inference strongly support the idea that B. aurea is the only species of the genus inhabiting the Southwestern Atlantic region. Our analyses revealed a complex population
pattern characterized by the existence of long-term highly structured genetic assemblages of mixed stocks. Each monophyletic
entity included individuals from different collecting sites, different age groups and collected in different years. Our data
also suggest that the recruitment of unrelated mtDNA haplotypes carried out by individuals within schools could be occurring
in the same nursery areas revealing the existence of many different maternal lineages. A scenario where different simultaneously
and successively mixed mtDNA lineages remain historically connected through basal haplotypes among different clades could
explains more accurately the complex and ordered metapopulation dynamic found in this pelagic fish. 相似文献
995.
Acroporid corals are the main reef-building corals that provide three-dimensional habitats for other reef organisms, but are
decreasing on many reefs worldwide due to natural and anthropogenic disturbances. In this study, temporal patterns of larval
settlement and survivorship of two broadcast-spawning acroporid coral species, Acropora muricata and A. valida, were examined through laboratory rearing experiments to better understand the potential for larval dispersal of this important
coral group. Many larvae were attached (but not metamorphosed) to settlement tiles on the first examination 3–4 days after
spawning (AS). The first permanent larval settlement (i.e. metamorphosed and permanently settled juvenile polyps) occurred
at 5–6 days AS, and most larval settlement (85–97% of total) occurred within 9–10 days AS. Larval survivorship decreased substantially
to around 50% by the first week of the experiment and to approximately 10% by the second to third week. The rates of larval
attachment, settlement, and the initial drop in survivorship of larvae suggest that effective dispersal of some acroporid
species may largely be completed within the first few weeks AS. 相似文献
996.
Nuxia L. Espinoza-Fuenzalida Martin Thiel Enrique Dupre J. Antonio Baeza 《Marine Biology》2008,155(6):623-635
Sexual systems vary considerably among caridean shrimps and while most species are gonochoric, others are described as sequential
protandric hermaphrodites or simultaneous hermaphrodites with an early male phase. At present, there is confusion about the
sexual system exhibited by several species mostly because those studies attempting to reveal their sexual system draw inferences
solely from the distribution of the sexes across size classes. Here we investigated the sexual system of the shrimp Hippolyte williamsi from Chile to determine if the species is protandric or gonochoric with sexual dimorphism (males smaller than females). Morphological
identification and size frequency distributions indicated that the population comprised small males, small immature females,
and large mature females, which was confirmed by dissections. No transitional individuals were found. Males maintained in
the laboratory molted 1–8 times, and many grew up to reach sizes observed in only a small fraction of males in the field.
No indication of sex change was recorded. Our results indicate that H. williamsi is a sexually dimorphic gonochoric species and emphasizes the importance of using several kinds of evidence (size measurements,
growth experiments, morphological dissections, and histological studies) to reveal the sexual system of Hippolyte species. Whether the observed size dimorphism between males and females in many species of Hippolyte is expression of contrasting sexual and natural selection, and whether divergent sexual fitness functions can contribute
to the evolution of hermaphroditism remains to be revealed in future studies. 相似文献
997.
J. Ashley T. Booth Henry A. Ruhl Lawrence L. Lovell David M. Bailey Kenneth L. SmithJr 《Marine Biology》2008,154(6):933-941
The 17-year time-series study at Station M in the NE Pacific has provided one of the longest datasets on deep-sea ophiuroids
to date. Station M is an abyssal site characterized by low topographical relief and seasonal and interannual variation in
surface-derived food inputs. From 1989 to 2005, over 31,000 ophiuroid specimens were collected. Size–frequency distributions
of the four dominant species, Ophiura bathybia, Amphilepis patens, Amphiura carchara and Ophiacantha
cosmica, were examined for recruitment and the role of surface-derived food supplies on body size distributions. Juveniles were collected
in sediment traps and used to investigate settlement patterns and seasonality. Trawl samples showed no indication of seasonal
changes in recruitment to larger size classes; however, there was evidence of seasonal settling of juveniles. Interannual
differences in median disk diameters and size distributions of trawl-collected adults are greater than those at the seasonal
scale. Three of the four species, O. bathybia, A. patens and O.
cosmica, had co-varying monthly median disk diameters, suggesting they may have a similar factor(s) controlling their growth and
abundance. Interannual differences in monthly size distributions were generally greater than those between seasons. Cross-correlations
between the particulate organic carbon (POC) flux (food supply) and size distribution indices for O. bathybia, A. patens and O.
cosmica all were significant indicating that increases in food supply were followed by increases in the proportion of smaller size
classes after approximately 17–22 months. These findings suggest that food inputs are indeed an important factor influencing
deep-sea ophiuroid populations on interannual time scales, more generally supporting the long-hypothesized connection between
food availability and population size structure in the deep sea.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
998.
A time series study of the copepods Calanus chilensis and Centropages brachiatus was carried out at the coastal upwelling zone of Mejillones (23°S, northern Chile), to analyze their annual life cycles in
association with upwelling variation. These species co-exist in the upwelling zone. Weekly sampling of zooplankton and oceanographic
variables including Chlorophyll-a and phytoplankton composition were obtained during January–December 2002 at a fixed station (ca. 90 m depth). Stages of abundances,
their proportions, changes in body length of adult females, sex ratio and egg production rate (EPR), were used as proxies
to examine copepods’ demography. Upwelling, assessed by weekly Ekman transport and oceanographic conditions, was intermittent
throughout the year with lack of periodicity components. Populations of both copepod species did not correlate with these
non-predictable upwelling events. C. chilensis reproduced year-round and the population showed ca. 15 peaks of adults with an average time interval between peaks of 20 days.
C. brachiatus showed a similar life cycle, also having 15 peaks of adults at about 22 days of time intervals. Cross-correlation functions
and spectral analysis showed that both populations correlated positively through time, but not in phase, evidencing a time
lag for their reproductive cycles. The lag was also evident in their population abundances. Both species differ in their development
rates and this may result in non-in phase life cycles. Our findings suggest that species-dependent attributes, such as development
rates, modulated by adaptations to temperature, might impose constraints in the species life cycles determining the population
cycles. Such attributes must be considered when modeling and understanding population dynamics and secondary production of
copepods. 相似文献
999.
James D. McCleave 《Marine Biology》2008,155(3):249-262
This study reviewed literature on spawning times for three north temperate species of anguillid eels estimated by sampling
for small leptocephali (larvae) at sea and for several temperate and tropical species by back-calculating from putative daily
ages derived from otolith increment analysis of glass eels that recruited to coastal waters. Estimates from otoliths of European
eels, Anguilla anguilla, American eels, Anguilla rostrata, and Japanese eels, Anguilla japonica, imply much more protracted spawning seasons than are indicated by sampling at sea during various times of year. European
eels are inferred to spawn year-round from otolith analysis, but the smallest, recently hatched leptocephali are found only
in late winter and spring. From otoliths, the spawning times of these three species are all estimated to occur much later
in the year than when small leptocephali are found at sea, indicating that ages appear to be underestimated. For these and
other temperate and tropical eels, there are inconsistencies in assigned ages among various studies, which are most extreme
for the European eel. This species has the longest larval migration and often has an opaque zone in the glass eels’ otoliths
where it is difficult to discern growth increments. These inconsistencies suggest that interpretation of otolith growth increments
is incorrect at least in some studies, and the apparently consistent mismatch between otolith and sea-sampling studies suggests
that increments may not always be formed at some period during the unusual early life history of anguillids. Because daily
increments may be formed in eels during most of their early life history, future research is needed to determine the cause
of the mismatch of glass eel aging studies and the apparent spawning times of eels offshore.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
James D. McCleaveEmail: |
1000.
Many symbioses involve multiple partners in complex, multi-level associations, yet little is known concerning patterns of
nutrient transfer in multi-level marine mutualisms. We used the anemonefish symbiosis as a model system to create a balance
sheet for nitrogen production and transfer within a three-way symbiotic system. We quantified diel patterns in excretion of
ammonia by anemonefish and subsequent absorption by host sea anemones and zooxanthellae under laboratory conditions. Rates
of ammonia excretion by the anemonefish Amphiprion bicinctus varied from a high of 1.84 μmole g−1 h−1 at 2 h after feeding, to a basal rate of 0.50 μmole g−1 h−1 at 24–36 h since the last meal. Conversely, host sea anemones Entacmaea quadricolor absorbed ammonia at a rate of 0.10 μmole g−1 h−1 during the daytime in ammonia-enriched seawater, but during the night reduced their absorption rate to near zero, indicating
that ammonia uptake was driven by zooxanthella photosynthesis. When incubated together, net ammonia excretion was virturally
zero, indicating that host anemones absorbed most of the ammonia produced by resident fish. Adult anemonefish weighed about
11 g under laboratory conditions, but on the coral reef may reach up to 64 g, resulting in a maximal potential ammonia load
of >200 μmole h−1 produced by two adult fish during daylight hours. In contrast, host sea anemones weighed about 47 g in the laboratory, but
under field conditions, large individuals may reach 680 g, so their maximal ammonia clearance rates may reach about 70 μmole h−1 during the daytime. As such, the ammonia load produced by adult anemonefish far exceeds the clearance rate of host anemones
and zooxanthellae. Ammonia transfer likely occurs mainly during the daytime, when anemonefish consume zooplankton and excrete
rapidly, and in turn the zooxanthellae are photosynthetically active and drive rapid ammonia uptake. We conclude that zooplanktivorous
fishes that form mutualisms with coral reef cnidarians may serve as an important link between open water and benthic ecosystems,
through the transfer of large quantities of nutrients to zooxanthellate hosts, thus enhancing coral reef productivity. 相似文献