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81.
82.
Sponges display a variety of reproductive strategies that have the potential to influence population genetic structure. Histological examination of ten reproductive individuals of the Western Australian sponge Haliclona sp. showed that this species broods embryonic larvae that are potentially limited in dispersal capabilities. Because sponges have the potential to propagate in a number of modes, allozyme electrophoresis was used to assess the relative importance of asexual and sexual reproduction to recruitment, and to quantify genetic subdivision over different spatial scales. Tissue samples from 227 sponges were collected from reefs within two areas 400 km apart: Hamelin Bay and Rottnest Island. Contrary to expectations for highly clonal populations, genotypic diversity within sites was high, no linkage disequilibrium was found, and there was no evidence of genotypic clustering within reefs. There was no genetic evidence that asexual reproduction is important for the maintenance of populations. Genetic comparisons were consistent with mixing of sexually produced recruits within reefs, on a scale up to a few hundred metres, but significant genetic subdivision between reefs (FST=0.069 at Hamelin Bay, 0.130 at Rottnest Island) indicated that water gaps of several hundred metres are effective at preventing dispersal. Subdivision between the two areas, separated by 400 km, was moderately greater (FST=0.142) than within, but the same alleles were predominant in the two areas. These genetic patterns are consistent with limited dispersal capabilities of brooded larvae.Communicated by G.F. Humphrey, Sydney 相似文献
83.
A comparison of temperate reef fish assemblages recorded by three underwater stereo-video techniques 总被引:1,自引:0,他引:1
Dianne?L.?WatsonEmail author Euan?S.?Harvey Marti?J.?Anderson Gary?A.?Kendrick 《Marine Biology》2005,148(2):415-425
Three underwater stereo-video techniques were used to sample the relative densities and species richness of temperate reef fish assemblages at three reef locations and two habitats (high- and low-relief reef) within Hamelin Bay, south-western Australia. The three techniques compared were diver-operated stereo-video strip transects, baited remote stereo-video and unbaited remote stereo-video. While unbaited remote stereo-video and diver-operated stereo-video transects recorded greater species richness at high compared to low-relief reefs, baited remote stereo-video recorded similar species richness at the two habitat types. The diver-operated stereo-video system was manoeuvred through caves and under overhangs recording small, cryptic, cave-dwelling species that were not recorded by either remote video techniques (Trachinops noarlungae, Trachinops brauni, Chromis klunzingeri, Trachichthys australis). Both remote video techniques recorded greater species richness and relative density of the most common species of Labridae, Ophthalmolepsis lineolatus. Baited remote video recorded the rarer, large predatory fish species (e.g. Seriola hippos, Glaucosoma hebraicum, Heterodontus portusjacksoni). None of the techniques sampled small cryptic fish families such as Gobiidae or Blenniidae. A combination of survey techniques is recommended for comprehensive fishery-independent studies that aim to sample broad components of fish assemblages.An erratum to this article can be found at 相似文献
84.
Digital simulation models of radiocesium cycling in Turkey Oaks were developed from in situ 134Cs tagging studies. Predictions of 134Cs steady-state distribution for 3-, 4- and 5-compartment, donor-controlled models were compared with the estimated fallout 137Cs distribution as a measure of model validation; output from the 5-compartment model compared best. Sensitivity analysis demonstrated that Turkey Oak burden of 134Cs was equally sensitive to the output rate from the tree compartment and the availability of 134Cs for uptake (i.e., presence in the root zone) but not the rate of uptake by Turkey Oaks. Observed distribution and model predictions indicate that radiocesium is readily bioaccumulated by Turkey Oaks (~13% of the ecosystem burden) from the soil and is cycled within the sand hills—Turkey Oak ecosystem. 相似文献
85.
86.
Genetic variation in defense chemistry in wild cabbages affects herbivores and their endoparasitoids 总被引:2,自引:0,他引:2
Gols R Wagenaar R Bukovinszky T van Dam NM Dicke M Bullock JM Harvey JA 《Ecology》2008,89(6):1616-1626
Populations of wild Brassica oleracea L. grow naturally along the Atlantic coastlines of the United Kingdom and France. Over a very small spatial scale (i.e., <15 km) these populations differ in the expression of the defensive compounds, glucosinolates (GS). Thus far, very few studies have examined interactions between genetically distinct populations of a wild plant species and associated consumers in a multitrophic framework. Here, we compared the development of a specialist (Pieris rapae) and a generalist (Mamestra brassicae) insect herbivore and their endoparasitoids (Cotesia rubecula and Microplitis mediator, respectively) on three wild populations and one cultivar of B. oleracea under controlled greenhouse conditions. Herbivore performance was differentially affected by the plant population on which they were reared. Plant population influenced only development time and pupal mass in P. rapae, whereas plant population also had a dramatic effect on survival of M. brassicae. Prolonged development time in P. rapae corresponded with high levels of the indole GS, neoglucobrassicin, whereas reduced survival in M. brassicae coincided with high levels of the aliphatic GS, gluconapin and sinigrin. The difference between the two species can be explained by the fact that the specialist P. rapae is adapted to feed on plants containing GS and has evolved an effective detoxification system against aliphatic GS. The different B. oleracea populations also affected development of the endoparasitoids. Differences in food-plant quality for the hosts were reflected in adult size in C. rubecula and survival in M. mediator, and further showed that parasitoid performance is also affected by herbivore diet. 相似文献
87.
Comparison of fine-scale acoustic monitoring systems using home range size of a demersal fish 总被引:1,自引:0,他引:1
Kelly S. Andrews Nick Tolimieri Greg D. Williams Jameal F. Samhouri Chris J. Harvey Phillip S. Levin 《Marine Biology》2011,158(10):2377-2387
We compared the results from fixed acoustic transmitters and transmitters implanted in lingcod Ophiodon elongatus provided by two fine-scale passive acoustic monitoring systems: the older Vemco? Radio Acoustic Positioning (VRAP) system and the newer VR2W Positioning System (VPS) with either three or four receivers.
The four-receiver VPS method calculated five times more positions of lingcod than VRAP and more than twice as many as the
three-receiver VPS. Calculated positions of fixed transmitters were less precise with VRAP than either VPS approach. Measurements
of home range for lingcod were similar between the four-receiver VPS and VRAP, which were both greater than the three-receiver
VPS. Comparisons varied when lingcod were in/near complex habitats. As new technology develops, it is important to understand
how new methods compare to previous methods. This may be important when describing patterns of movement or habitat use in
the context of changes in habitat or management efforts. 相似文献
88.
89.
Constraints on the use of anthropogenic radionuclide-derived chronologies for saltmarsh sediments 总被引:1,自引:0,他引:1
Numerous studies have employed anthropogenic radionuclides deposited in accumulating sediments to derive chronologies for use in investigations of geomorphological processes and in reconstructing temporal trends in contaminant deposition. However, relatively few have interrogated their use in systems that erode as well as accrete sediment, or have addressed limitations in their applicability in systems that experience variable rates of accumulation. This paper examines the utility of Sellafield-derived radionuclides for reconstructing sedimentary processes in two contrasting saltmarsh systems in the south-west of Scotland. Sedimentation rates and patterns derived from the radionuclide chronologies are outlined and compared to results established through conventional geomorphological methods. The results confirm that the vertical distribution of anthropogenic radionuclides can be useful in determining sedimentation rates, but that these cannot always be used as indicators of contemporary processes, particularly where erosion is occurring. Their use is also limited unless profiles are obtained from spatially diverse geomorphological units. Integrating the use of chronologies with other independent methods secures more robust data for assessing both marsh sustainability and their longevity as radionuclide sinks. 相似文献
90.
Nestor E. Bosch Jacquomo Monk Jordan Goetze Shaun Wilson Russell C. Babcock Neville Barrett Jock Clough Leanne M. Currey-Randall David V. Fairclough Rebecca Fisher Brooke A. Gibbons David Harasti Euan S. Harvey Michelle R. Heupel Jamie L. Hicks Thomas H. Holmes Charlie Huveneers Daniel Ierodiaconou Alan Jordan Nathan A. Knott Hamish A. Malcolm Dianne McLean Mark Meekan Stephen J. Newman Ben Radford Matthew J. Rees Benjamin J. Saunders Conrad W. Speed Michael J. Travers Corey B. Wakefield Thomas Wernberg Tim J. Langlois 《Conservation biology》2022,36(2):e13807
Marine fisheries in coastal ecosystems in many areas of the world have historically removed large-bodied individuals, potentially impairing ecosystem functioning and the long-term sustainability of fish populations. Reporting on size-based indicators that link to food-web structure can contribute to ecosystem-based management, but the application of these indicators over large (cross-ecosystem) geographical scales has been limited to either fisheries-dependent catch data or diver-based methods restricted to shallow waters (<20 m) that can misrepresent the abundance of large-bodied fished species. We obtained data on the body-size structure of 82 recreationally or commercially targeted marine demersal teleosts from 2904 deployments of baited remote underwater stereo-video (stereo-BRUV). Sampling was at up to 50 m depth and covered approximately 10,000 km of the continental shelf of Australia. Seascape relief, water depth, and human gravity (i.e., a proxy of human impacts) were the strongest predictors of the probability of occurrence of large fishes and the abundance of fishes above the minimum legal size of capture. No-take marine reserves had a positive effect on the abundance of fishes above legal size, although the effect varied across species groups. In contrast, sublegal fishes were best predicted by gradients in sea surface temperature (mean and variance). In areas of low human impact, large fishes were about three times more likely to be encountered and fishes of legal size were approximately five times more abundant. For conspicuous species groups with contrasting habitat, environmental, and biogeographic affinities, abundance of legal-size fishes typically declined as human impact increased. Our large-scale quantitative analyses highlight the combined importance of seascape complexity, regions with low human footprint, and no-take marine reserves in protecting large-bodied fishes across a broad range of species and ecosystem configurations. 相似文献