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The biomass of macro- and interstitial fauna on clean and wrack-covered beaches in Western Australia
Anton McLachlan 《Estuarine, Coastal and Shelf Science》1985,21(4):587-599
The benthic faunal spectrum including bacteria, protozoans, meiofauna, wrack epifauna and macrofauna, was quantitatively surveyed on two modally reflective, moderate energy, Western Australian beaches. The more exposed beach had coarser sand, no intertidal macrofauna and a poor interstitial fauna. The less exposed beach had a large deposit of wrack totalling 161 kg m?1 dry mass concentrated on the lower shore. The amphipod Allorchestes compressa was abundant in the fresh wrack comprising most of the macrofauna. There were also fairly abundant small epifauna on the wrack. Dry biomass of macrofauna, epifauna, meiofauna, protozoans and bacteria was 0, 0, 15, 4 and 180 g m?1 on the more exposed beach and 160, 3, 112, 9 and 901 g m?1 on the less exposed beach with wrack. On the latter beach there was an inverse correlation between meiofaunal densities and the densities of protozoans and bacteria, suggesting grazing by the former on the latter. On both beaches meiofauna was concentrated in the mid- to upper beach, protozoans near the surface and bacteria in the mid- to lower beach. It is estimated that bacteria are responsible for most of the secondary production on both beaches. 相似文献
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Ten exposed sandy sites covering a range from reflective to dissipative beaches were sampled in south-central Chile to evaluate: (1) spatial changes in species richness, abundance and biomass of the intertidal macroinfauna in response to changes in mean grain size, beach face slope and beach type, and (2) spatial changes in abundance, biomass and body sizes of the most abundant species in response to changes in the physical factors. The number of species, abundance and biomass per beach in general decreased with increasing particle size and beach face slope (steeper beaches) and increased from reflective to dissipative conditions. The best fit for number of species was with Dean's parameter, a measure of beach type, whereas for abundance and biomass the best fits were found with particle size. The isopod Excirolana braziliensis and the anomuran Emerita analoga increased in abundance and biomass towards dissipative conditions, whereas Excirolana hirsuticauda showed the opposite trend in biomass and was significantly larger in beaches with steeper profiles. It is concluded that responses to changes in beach type are more pronounced at community level than within species populations. 相似文献
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The effects of varying intensities of off-road vehicle and pedestrian traffic on vegetation height and percent-cover were investigated at two sites representing pioneer and climax dune shrubland communities in South African dune systems. In all cases, a decreasing trend in vegetation height and percentage cover subsequent to application of the treatments was evident, although this was more clear in the shrub than in the pioneer community. The impact on vegetation variables increased with increasing intensity of vehicle and pedestrian treatments. Vehicles driven along a curved path resulted in greater vegetation destruction than those driven along a straight path. High intensity (single application) treatments resulted in an initial decrease in vegetation height and cover immediately after the impact, which was followed by a further decline over the next 3 months. This two-step response was attributed to the subsequent gradual death of the vegetation which was not evident immediately following the impact. Due to their faster growth rate, pioneer dune communities appear to have the capacity to recover following impacts, while dune shrub communities tend to be more vulnerable, exhibiting signs of damage for longer periods. The results of this study have value for managers of coastal dune systems, particularly those impacted by human recreational activities. 相似文献
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A. Y. Kwarteng S. M. Al-Hatrushi W. K. Illenberger A. McLachlan 《Arabian Journal of Geosciences》2016,9(9):557
The nature of Al Batinah coast beach sediments in the Sultanate of Oman was investigated by the analysis of grain size and mineralogy. The beach sediments, mostly light-medium gray green, were predominantly fine sands, with the average grain size of all samples about 200 μm. Some of the particles were gravel (2–16 mm), and some were even larger pebble-size particles (16–256 mm). Some mud (sediment <63 μm) was present, mostly in the sub-tidal sediments. The majority of the samples were skewed to the coarse size with coarse tail partly due to the presence of shell fragments. Approximately 50 % of the beach sediments were quartz with different varieties based on shape and size. The second major component of beach sediment was calcium carbonate which varied from 10 to 65 %. The other components in decreasing order consisted of microbreccia, feldspar, pyroxene, igneous rock fragments, biotite flakes, and heavy minerals. The levels of carbonate were lower in NW Al Batinah coast from Harmul to Al Khaburah but were higher in the SE from Al Khaburah to Al Ghubrah. This could be attributed to either lower carbonate production or more sediment input by wadis along the north-western part of Al Batinah coast. The unique and complex nature of these sediments is largely due to the geology of the terrestrial source area in the Hajar Mountains which contains the famous Samail ophiolite complex and the weak sorting along the shoreline in these tide-modified beaches. 相似文献
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Abstract A series of meetings of two ‘Citizen Panels’ were held to explore public perceptions of off-shore carbon dioxide (CO2) capture and storage (CCS). In addition, a face-to-face survey of 212 randomly selected individuals was conducted. We found that, on first hearing about CCS in the absence of any information on its purpose, the majority of people either do not have an opinion at all or have a somewhat negative perspective. However, when (even limited) information is provided on the role of CO2 storage in reducing CO2 emissions to the atmosphere, opinion shifts towards expressing slight support for the concept. Support depends, however, upon concern about human-caused climate change, plus recognition of the need for major reductions in CO2 emissions. It also depends upon CCS being seen as just one part of a wider strategy for achieving significant cuts in CO2 emissions. A portfolio including renewable energy technologies, energy efficiency, and lifestyle change to reduce demand was generally favoured. CCS can be part of such a portfolio, but wind, wave, tidal, solar and energy efficiency were preferred. It was felt that uncertainties concerning the potential risks of CCS had to be better addressed and reduced; in particular the risks of accidents and leakage (including the potential environmental, ecosystem and human health impacts which might result from leakage). 相似文献
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I. P. Holman M. D. A. Rounsevell G. Cojacaru S. Shackley C. McLachlan E. Audsley P. M. Berry C. Fontaine P. A. Harrison C. Henriques M. Mokrech R. J. Nicholls K. R. Pearn J. A. Richards 《Climatic change》2008,90(1-2):5-30
This paper provides an overview of the development of the ‘Regional Impact Simulator’ – a user friendly software tool designed to allow stakeholders to perform integrated assessments of the effects of climate and/or socio-economic change on the important sectors and resources of two contrasting UK regions. This includes the assessment of agriculture, water resources, biodiversity and coastal and river flooding. The tool arose from the need to further develop the methods applied in the earlier RegIS project, which was the first local to regional integrated assessment in the UK. The limitations of RegIS included very long run times, a limited number of simulations, incomplete linkages between models and no allowance for scenario uncertainty. Based upon the stakeholder needs identified within RegIS, a series of guiding principles were developed with Steering Committee stakeholders, which informed the concept of the ‘Regional Impact Simulator’ including functionality, appearance and complexity. An Integrated Assessment Methodology based upon the Drivers-Pressure-State-Impact-Response (DPSIR) framework facilitated the integration of multiple models, scenarios and datasets within the software interface. The development of the ‘Regional Impact Simulator’ provides a test-bed for further studies of stakeholder-led, regional, integrated assessment, and provides an opportunity to learn the many lessons in undertaking such studies. 相似文献
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Anton McLachlan 《Marine environmental research》1982,6(1):37-47
Exposed sandy beaches filter huge volumes of sea water daily as a result of wave and tide action. A regression model is developed which predicts the volume of water filtered daily by a beach as a function of tide range, beach slope and sand particle size. From these parameters estimates are also made of intertidal distance, the degree of expansion of the intertidal above the still water tide range by wave action and the average path length through the sand interstices percolated by filtered sea water. An equation is derived relating the degree of mineralisation of organic matter in the filtered sea water to the distance filtered through the sand and the sand particle size. Employing all this information, a simple model is used to estimate the volumes of sea water filtered and the amounts of inorganic nitrogen regenerated by intertidal sandy beaches over a range of physical conditions. The implications of this nutrient generation for the inshore zone are discussed. 相似文献
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Effects on sandy beach microfauna of soluble pollutants, such as might be associated with an oil spill, were investigated in terms of nitrate generation. Nitrate generation by the microfauna in small sand columns in the laboratory was severely inhibited by water-soluble fractions of crude oil, dispersant and oil/dispersant mixtures in order of increasing effects. Short-term effects of such pollutants on nutrient regeneration by exposed sandy beaches are discussed. 相似文献