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141.
Ruth Fernández Susana García-Tiscar M. Begoña Santos Alfredo López Jose A. Martínez-Cedeira Jason Newton Graham J. Pierce 《Marine Biology》2011,158(5):1043-1055
Skin and muscle from 43 bottlenose dolphins (38 juveniles/adults, 5 calves) stranded in NW Spain were analysed to determine
whether stable isotope ratios (δ13C and δ15N) could be used to assess dietary variation, habitat segregation and population substructure. Results were compared with
published stomach contents data. Stable isotope ratios from 17 known prey species were also determined. Isotope ratios of
the main prey (blue whiting, hake) varied significantly in relation to fish body size. Dolphin calves showed significant heavy
isotope enrichments compared to adult females. Excluding calves, δ15N decreased with increasing dolphin body size, probably related to an ontogenetic shift in diet towards species at lower trophic
levels, e.g. on blue whiting as suggested by stomach content results. Bottlenose dolphins were divided into two putative populations
(North, South) based on previous genetic studies, and values of δ13C and δ15N differed significantly between these two groups, confirming the existence of population structuring. 相似文献
142.
Anne H. Beaudreau Kelly S. Andrews Donald A. Larsen Graham Young Brian R. Beckman 《Marine Biology》2011,158(2):439-450
The physiological response of a fish to its environment is mediated through the endocrine axis controlling growth. Therefore,
growth-regulating hormone levels can serve as ecologically relevant indicators of fish growth rate. We quantified variation
in plasma insulin-like growth factor-I (IGF-I) to evaluate its potential as an indicator of growth in lingcod, an economically
and ecologically important bottomfish species in the northeast Pacific. An information-theoretic model selection approach
was used to test the hypothesis that variation in lingcod IGF-I is related to season, body size, and gonadal steroid concentration.
Season and a length × season interaction were the most important predictors of plasma IGF-I among the variables we evaluated,
suggesting that season and body size should be explicitly accounted for when interpreting endocrine patterns in wild fish
populations. This is among the few studies that have measured and interpreted patterns of IGF-I in wild fish and the first
to describe seasonal endocrine profiles in lingcod. 相似文献
143.
Mass individual pairing or pseudo-copulation of the sea star Archaster angulatus was observed in November and December 2009, suggesting a late-spring/summer spawning period for this species on the west
coast of Australia. Detailed measurements were made on the second of these occasions. Density of sea stars was 1.11 per m2 and 68.5% were in mating pairs. Copulating pairs were mostly male on female, occasionally male on male. There was no difference
in size between males and females in mating pairs. No evidence was found to indicate mating and spawning is coincident with
lunar or tidal cycles. Females outnumbered males by more than 20%, but the difference in sex ratio was not statistically significant.
Analysis of the reproductive cycle revealed that gonad indices reached their peak in October and declined from then until
January. Histological sections of gonads confirmed that sea stars are in peak reproductive condition in October and November
and are fully spent by January. Males have a much lower (ca. 1/3rd) gonad index than females when each are in peak reproductive
condition, the second lowest recorded for any sea star. Pyloric caecae indices showed little annual variation and monthly
averages of just 3–4% are among the lowest ever recorded for an asteroid. It is suggested that these characteristics are associated
with the copulatory behaviour of the deposit feeding A. angulatus, enabling the species to maintain a high level of fertilisation success while also minimising the allocation of energy to
gonad development in habitats with low or variable food availability. However, it is still difficult to explain why a species
which ensures a high level of fertilisation by pseudo-copulation also does this en masse and synchronously. One hypothesis
is that competition for males and the benefits of having eggs fertilised by multiple males favours both synchrony and aggregation. 相似文献
144.
This study measured and analyzed the outdoor airborne endotoxin concentration, on particulate matter (PM2·? and PM1?), for two cities in the interior of British Columbia, Canada. Samples were collected throughout one seasonal cycle, from October 2005 to September 2006. It was found that concentrations were generally highest in the summer and fall, and lowest in the winter and spring. Temperature and relative humidity were found to be most influential, with highest endotoxin concentrations recorded during warm periods and moderate relative humidity (35 to 75 percent). No clear association of concentration with wind direction was observed. Results were comparable between the two cities considered in this study, and concentrations were similar to or slightly higher than those reported by other studies considering urban locations. Endotoxin concentration was also found to be positively associated with agricultural dust sources identified by a source apportionment study conducted at one of the sampling locations. 相似文献
145.
Tim P. Lynch Robert Harcourt Graham Edgar Neville Barrett 《Environmental management》2013,52(6):1341-1354
Between 2001 and 2009, 26 marine-protected areas (MPA) were established on the east Australian seaboard, at least in part, to manage human interactions with a critically endangered population of grey nurse shark, Carcharias taurus. This network is spread across six MPA systems and includes all 19 sites outlined in the National Recovery Plan for C. taurus, though five sites remain open to some forms of fishing. The reserve network has complex cross-jurisdictional management, as the sharks occur in waters controlled by the Australian states of New South Wales (NSW) and Queensland, as well as by the Commonwealth (Federal) government. Jurisdiction is further complicated by fisheries and conservation departments both engaging in management activities within each state. This has resulted in protected area types that include IUCN category II equivalent zones in NSW, Queensland, and Commonwealth marine parks that either overlay or complement another large scaled network of protected sites called critical habitats. Across the network, seven and eight rule permutations for diving and fishing, respectively, are applied to this population of sharks. Besides sites identified by the recovery plan, additional sites have been protected as part of the general development of MPA networks. A case study at one of these sites, which historically was known to be occupied by C. taurus but had been abandoned, appears to shows re-establishment of an aggregation of juvenile and sub-adult sharks. Concurrent with the re-establishment of the aggregation, a local dive operator increased seasonal dive visitation rates at the site fourfold. As a precautionary measure, protection of abandoned sites, which includes nursery and gestating female habitats are options that may assist recovery of the east coast population of C. taurus. 相似文献
146.
Abstract Community-based monitoring (CBM) activities in Canada are increasing. A conceptual framework developed for and used to guide a pilot CBM project in 31 Canadian communities is evaluated. The framework provided the strategic direction necessary for successful implementation of the pilot and proved useful in the training of community coordinators hired for the project. Limitations of the framework include its inadequate attention to community diversity, its linearity, and insufficient expression of the adaptive and synergistic nature of its components. In order to support local sustainability, CBM appears to require an approach that is context-specific, iterative, and adaptive. Given these emergent characteristics, an enhanced conceptual framework for CBM in Canada is developed based on four dynamic themes: community mapping, participation assessment, capacity building, and information delivery. 相似文献
147.
Puerto Rican Parrots and Potential Limitations of the Metapopulation Approach to Species Conservation 总被引:1,自引:0,他引:1
148.
149.
J. B. Graham 《Marine Biology》1970,5(2):136-140
Mnierpes macrocephalus
(Günther) inhabits the steep, current-swept shores of the tropical east Pacific Ocean; it makes frequent terrestrial excursions. Laboratory and field studies were undertaken to assess the importance of these excursions in its ecology. Several morphological features, such as body shape, padded ventral surfaces, thickened fin rays and incised fin membranes are related to its capacity for terrestrial locomotion. Its body scalation reduces desiccation. M. macrocephalus can endure prolonged exposure to air, apparently by respiring aerially. Its eyes are highly adapted for terrestrial vision through the presence of flattened corneas. Terrestriality appears to play a significant part in the capacity of M. macrocephalus to orientate at the oscillating water surface where it resides. 相似文献
150.
J.B. Free Ingrid H. Williams R.J.F.H. Pinset A. Townshend M.S. Basi C.L. Graham 《Environment international》1983,9(1):9-12
The metal contents of pollen loads gathered by honeybees have been determined in areas with known concentrations of soil-borne heavy metals. The manganese, zinc, copper, and lead contents of the pollen loads reflected those of the environment, indicating that honeybee colonies might be used to sample areas. 相似文献