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1.
Rocky littoral communities of the Azores are dominated by macroalgae where turf formations represent the main life form as on many subtropical and tropical shores. The present study aimed at describing and classifying benthic intertidal biotopes of the Azores using clear quantification and data analysis methodologies to be used in similar studies for spatial and/or temporal comparison. This numerical approach intends to have management and conservation applicability. Thirty study locations along the coast of São Miguel island were characterised by substratum type (cobbles, boulders or bedrock – different stability levels) and exposure to wave action (high, medium or low exposure), from June to August 2002. Algae, sessile and sedentary invertebrates were recorded along transects, and the more conspicuous taxa quantified. Community structure is mainly shaped by substratum stability – unstable cobble communities are separate from those of more stable boulders and bedrock. Boulders present an intermediate community composition between cobbles and bedrock. Exposure to wave action induces smaller variation in community composition. Sixteen biotopes have been recognised. Ultimately the present paper provides an objective set of biotope definition tools for a broad public whose interest focuses on spatial and temporal comparison of coastal communities and associated habitats. 相似文献
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Summary The zonation of rocky shore biota on Heard Island is described for the first time, related to a universal zonation scheme and compared with that recorded for other sub-Antarctic localities. The Kelp Zone of holdfasts of the giant kelp, Durvillea antarctica (Chamisso) Hariot (one of the characteristic features of these regions) is confirmed as a sublittoral fringe. The occurrence of a Bare Zone within the littoral zone on sub-Antarctic shores is discussed. The possible roles of submersion, spray, freezing and predation by gulls in influencing the extent and composition of zones are discussed. 相似文献
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M. Cielo Bazterrica Brian R. Silliman Caitlin M. Crain 《Journal of experimental marine biology and ecology》2007,353(1):22-34
Many theories of consumer control of communities have come from studies conducted in relatively benign, temperate zone rocky intertidal systems. Here, we examine gastropod grazing and the maintenance of bare space on a dry, wind-swept rocky shore of Patagonia, Argentina. Two limpet species are the primary intertidal grazers. Siphonaria lessoni dominates mid and high intertidal zones, while Nacella magellanica dominates the lower zone. In all zones, limpet densities are positively correlated with bare space and the occurrence of cracks. Tethering experiments revealed that: (1) physical stress sets the upper distribution limit of both limpets, (2) predators, such as oyster catchers, regulate Nacella populations and may restrict them to cracks and vertical surfaces, and (3) desiccation stress appears to drive similar crack distribution patterns of Siphonaria in the upper intertidal. Experimental removal of limpets in each intertidal zone indicated that limpets have: (1) no detectable effect in the high intertidal where physical forces dominate community organization, (2) weak impacts at mid-elevations as grazing only limited the abundance of fleshy algae with physical forces again dominating community structure, and (3) relatively stronger, but still weak impacts in the low zone. These results suggest that grazing impacts on Argentine rocky shores are weak in comparison to the physical stresses (e.g. high winds, low humidity) that largely determine structure in this system. The dominance of physical forcing in this system occurs despite having similar grazer densities to other temperate, but comparatively wet, rocky shorelines (e.g. British Isles) where top-down control is strong. 相似文献
4.
Intertidal community composition along rocky shores in South-west Greenland: a quantitative approach
Signe Høgslund Mikael K. Sejr Jozef Wiktor Jr. Martin E. Blicher Susse Wegeberg 《Polar Biology》2014,37(11):1549-1561
The intertidal communities on rocky shores are directly subjected to climatic changes in air and water temperatures and to derived effects of climate change, such as changes in freshwater run-off and ice dynamics. Global warming occurs at elevated rates in Greenland and results in changing species distributions with range expansions to the north and new species entering terrestrial habitats from the south. There is, however, no quantitative knowledge of past or present species distribution in the littoral zone of Southern Greenland, an area which represents an important gateway for northern range expansions of temperate species. This study provides baseline information on abundances of macroorganisms in the eulittoral Southern Greenland. This knowledge will pave the way for future studies on the impact of climate change and anthropogenic activities on these communities. Nine sites, situated at different exposure levels, were investigated. A total of 22 taxa were recorded, suggesting low species richness. Patellid limpets and predators such as dogwhelks, starfish and crabs were absent. Total standing stock ranged from 0 to 31,898 g m?2. Species composition and biomasses were related to locally generated wave exposure, oceanic swells and ice scouring. The high standing stock at sheltered sites indicated that neither light, temperature nor nutrients, constrained buildup of biomass in this environment. Inshore seasonal measurements of water and air temperatures were recorded for the first time in the region, displaying low water temperatures and high variation in air temperatures, indicating lack of insulating stable sea ice in the area. Possible impacts of ongoing temperature changes are discussed based on recorded temperatures and meteorological data from the past 30 years. 相似文献
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Summary A SCUBA-diving survey of the macrobenthos of hard substrata in the sublittoral zone at subantarctic Marion Island was conducted during March and April 1988. Dense beds (12 kg m–2) of the kelp Macrocystis laevis occur in depths > 5 m. Durvillaea antarctica is found along the infralittoral fringe and Desmarestia rossi and Durvillaea sp. occur in a narrow zone from 3 m–6 m. Under-storey algae (chiefly rhodophytes) tend to decrease in biomass with depth, with mean values of 1.57 kg m–2 at 5m, 0.75 kg m–2 at 10m and 0.49 kg m–2 at 15 m. Encrusting coralline algae are particularly abundant in shallow areas (¯x = 0.92 kg m–2) but are insignificant in deeper areas. Total biomass of macrozoobenthos increased with depth with mean values of 0.12 kg m–2 at 5 m, 0.34 kg m–2 at 10 m and 0.46 kg m–2 at 15 m. Polychaetes, crustaceans, echinoderms, molluscs, sponges and bryozoans dominated the macrozoobenthos in terms of biomass. Approximately 200 species of macrobenthic animals were recorded and numerically, polychaetes, crustaceans, molluscs, nematodes and echinoderms dominated. The sublittoral benthos at Marion Island is compared with that occurring at other subantarctic and Antarctic islands, in particular, the Kerguelen Island group. Zoogeographic trends and the possible effects of nutrient input from seabird guano are briefly discussed. 相似文献
7.
Successional patterns are dependent on the nature of the substratum, water flow, concentrations of organics as well as the availability of bacteria, algal spores and invertebrate larvae in the coastal environment. Bacteria play an especially important role in biofilm formation as they are generally the earliest colonizers. In the present study, both winter and summer biofilm succession patterns were examined on glass coverslips inverted on experimental racks attached at two tidal levels on a sheltered shore in Hong Kong. In the succession, bacteria were followed by diatoms and cyanobacteria. Encrusting algae appeared in the late stages of the experiment (day 80 in summer and day 60 in winter). Colonization by bacteria was much slower in summer and their density remained low throughout the experimental period. The first appearance of diatoms and cyanobacteria, however, was more rapid in the summer. Bacteria and diatoms on the low-shore surfaces also had a faster succession rate than on the high-shore surfaces, suggesting that desiccation/aerial temperature are the causal factors for such differences. 相似文献
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1. A model was developed for the growth of intertidal algae with photosynthesis simulated both in air and in a tidal water column. Morphological data on dry mass per unit area and length–area relationships were used to separate the growth of different fucoid species. The relative growth rate of fronds at any height on the shore depended on a trade-off between net photosynthetic performance and tolerance to desiccation.
2. The simulated zonation patterns and growth rates were consistent with those observed previously for Fucus spp. and Pelvetia canaliculata .
3. The simulated growth of Ascophyllum nodosum was always slower than for the other species. This species did not form its characteristic distribution zones in simulations without including further processes in the model. However, Ascophyllum collected from the field could be separated into upper and lower shore morphologies which formed separate zones when they were simulated in competition with each other.
4. Several hypotheses were proposed concerning the relative locations and sharpness of interspecies boundaries on the shore. Zonation patterns were relatively insensitive to changes in most model parameters except the desiccation rate. 相似文献
2. The simulated zonation patterns and growth rates were consistent with those observed previously for Fucus spp. and Pelvetia canaliculata .
3. The simulated growth of Ascophyllum nodosum was always slower than for the other species. This species did not form its characteristic distribution zones in simulations without including further processes in the model. However, Ascophyllum collected from the field could be separated into upper and lower shore morphologies which formed separate zones when they were simulated in competition with each other.
4. Several hypotheses were proposed concerning the relative locations and sharpness of interspecies boundaries on the shore. Zonation patterns were relatively insensitive to changes in most model parameters except the desiccation rate. 相似文献
10.
Nancy J. O’Connor 《Biological invasions》2014,16(1):73-87
Populations of invading Asian shore crabs (Hemigrapsus sanguineus) and resident crabs (European green crab Carcinus maenas or species in the family Panopeidae) were monitored for up to 12 years along a south to north orientation on the open coast of Massachusetts and within the Narragansett Bay estuary, Rhode Island. At all sites, densities of resident crabs declined as H. sanguineus increased in abundance. Population dynamics were divided into 3 stages of the invasion (early, mid, late) based on statistically different densities of invading and resident crabs. Early in the invasion on the open coast, the relatively few H. sanguineus present had a wide range of individual sizes. By late in the invasion, relatively small crabs [<10 mm carapace width (CW)] constituted half of the population. Few seasonal differences occurred. Carcinus maenas, dominant at the coastal sites early in the invasion, showed strong recruitment of small individuals in the fall early in the invasion. Overall numbers of C. maenas declined as the H. sanguineus invasion progressed, and very few crabs >10 mm CW were present late in the invasion. In Narragansett Bay, a recruitment peak of H. sanguineus occurred shortly before it surged in population size, and large crabs were abundant late in the invasion. Geographic comparisons of H. sanguineus populations in southern New England showed similar growth trajectories. Monitoring populations of resident and invading species at multiple locations from early invasion through clear establishment of the invader allows a more complete understanding of the population dynamics of marine species invasions. 相似文献
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ROBERT E. SCHEIBLING 《Austral ecology》1994,19(2):141-149
Abstract Intertidal limestone platforms off Perth show a characteristic pattern of algal zonation, with dense macroalgal beds nearshore bounded by a ‘barren zone’ along the seaward edge. Abalone (Haliotis roei) and several species of limpets and chitons are abundant in the barren zone, which is generally devoid of non-coralline macroalgae. The relative importance of abalone versus limpets and chitons in limiting macroalgal abundance in the barren zone was evaluated by manipulating the presence of each group in a factorial experiment. Percentage algal cover was measured photographically in 0.25m2 plots at 1–2 month intervals for 9 months. Mean algal cover (mainly the foliose green alga, Ulva rigida) was highest in plots where all grazers were excluded (77–99%), intermediate where only limpets and chitons were excluded (37–85%), and lowest where only abalone were excluded (4–30%) or where no grazers were excluded (2–19%). The effect of limpets and chitons accounted for 55–89% of the variance in total algal cover, whereas the effect of abalone generally accounted for <10% of the variance. Similar results were obtained in terms of the biomass of Ulva rigida at the end of the experiment. Haliotis roei are relatively large and sedentary herbivores, feeding mainly on drift algae. Their effect on algal abundance was mediated both through pre-emption of space, which might otherwise be colonized by algae, and by grazing around their home scar. Limpets and chitons are smaller than abalone, but were much more abundant. Intensive grazing of the reef surface by limpets and chitons precluded the establishment of non-coralline macroalgae, even where abalone were absent. 相似文献
12.
Estimates of the predation rates of benthic nemerteans are often based on observations of single individuals, and consequently they may not be representative for all members of a population of these predators. Herein we conducted controlled and repeatable laboratory experiments on the predation rate of the hoplonemertean Amphiporus nelsoni Sánchez 1973, which is common at exposed rocky shores along the central Chilean coast. During the austral fall (April, May 2000), nemerteans were observed in relatively high numbers crawling in the intertidal zone during early morning or late-afternoon low tides. When these nemerteans were offered living amphipods held by a forceps, they immediately attacked the amphipods and fed on them. In the laboratory experiments, nemerteans preferred the amphipod Hyale maroubrae Stebbing, 1899, which is also very common in the natural habitat of A. nelsoni. The nemerteans preyed to a higher extent on small males and non-ovigerous females than would have been expected from their abundance. We suggest that these (non-reproductive) stages of H. maroubrae are very mobile and therefore have a high likelihood of encounters with nemerteans. Predation rates reached maxima when nemerteans were provided prey densities of four or more of their preferred prey species, H. maroubrae, furthermore indicating that encounter rates with prey may affect predation rates. In long-term laboratory experiments, A. nelsoni consumed more amphipods during low tide conditions than during high tide conditions. Many nemerteans in the field prefer particular environmental conditions (e.g. nocturnal low tides), which restricts the time available for successful feeding. In the long-term experiment, predation rates of A. nelsoni never exceeded 0.5 amphipods nemertean–1 d–1. Maximum feeding events were 3 or 4 amphipods nemertean–1 d–1, but this only occurred during 10 out of a possible 2634 occasions. Nemerteans that had consumed 3 or 4 amphipods during 1 day, consumed substantially less prey during the following days. Towards the end of the long-term experiment, average predation rates decreased to 0.2 amphipods nemertean–1 d–1, corresponding to predation rates reported for other nemertean species (0.1–0.3 prey items nemertean–1 d–1). We suggest that predation rates from laboratory experiments represent maximum estimates that may not be directly transferable to field populations. Additionally, low predator–prey encounter rates with preferred prey in the field may further limit the predation impact of nemertean predators in natural habitats. 相似文献
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Thirty-three sampling sites representing 11 lichen dominated plant communities on maritime rocks on Bornholm were analysed with respect to composition of the vegetation, number of animals present and gross taxonomic composition of the fauna. The specific fauna of one moss and seven lichen species was examined.
The lichen communities studied were largely the same as those found in similar studies in NW Europe, except for the recognition of a distinct Ramalina cuspidata community. The highest average number of animals per area was found in the Schistidium maritimum and the Ramalina siliquosa communities, whereas the highest average number of animals g−1 dry plant biomass was recorded in the Parmelia saxatilis community. Among the species examined Anaptychia fusca contained the highest average number of animals g−1 dry thallus and Ramalina cuspidata the lowest number, 114 and 7, respectively. Collemboles appeared to dominate in the moss Schistidium maritimum and in foliose lichens, whereas mites dominated in crustose and fruticose lichens. 相似文献
The lichen communities studied were largely the same as those found in similar studies in NW Europe, except for the recognition of a distinct Ramalina cuspidata community. The highest average number of animals per area was found in the Schistidium maritimum and the Ramalina siliquosa communities, whereas the highest average number of animals g
14.
Ryan R. Reisinger P. J. Nico de Bruyn Pierre A. Pistorius Marthán N. Bester 《Polar Biology》2010,33(4):571-574
We report two observations of adult male Antarctic fur seals, Arctocephalus gazella, preying on large octopods at subAntarctic Marion Island during July and August 2008. If Antarctic fur seals take cephalopods opportunistically, as previously suggested, our observations may be a rare event representing such opportunistic predation. 相似文献
15.
Several biological and physical factors change the rocky shore communities. The desiccation time and the tolerance of the intertidal species produce the vertical zonation. In many studies around the world, a temporal change in this zonation is presented.In Costa Rica, only studies that include temporal trends were carried out in Punta Mala and Montezuma, Pacific coast in 80's. The rocky intertidal of the Cocos Island National Park, Costa Rica were surveyed photographically. The Chatham bay was sampled in three expeditions (January 2007, October 2007 and April 2008). Photos corresponding to 25x25cm quadrats were taken with the goal to determine diversity and composition differences in rocky shore organisms between sampling dates. The Wafer bay was sampled in January and October 2007. The intertidal of Chatham consists of basaltic rock, while Wafer has basaltic and ignimbrite boulders. The main difference between sites were the higher algae cover (erect-frondose forms) and number of organism bands at Chatham bay. Temporal change was not found in the total cover of sessile fauna and autotrophs. The barnacle Tetraclita stalactifera, that occurs above the algal fringe (lower intertidal), was the invertebrate with the highest coverage. The mobile fauna biodiversity presented no significant trend between sampled months. However, the identity of species, their cover and their abundance showed a moderate temporal change. In October 2007, when the sea surface temperature was 23 degrees C the infralittoral zone had an increase in green algae cover. The red algae (crust and erect-frondose forms) were dominant in January and April. The pulmonate limpet, Siphonaria gigas and a bacterial biofilm at mid littoral showed a negative association. The snails of the high littoral and the supralittoral zone showed a temporal change in their abundance, but with contrasting patterns between sites. The temporal variation in the assemblages increased from the supralittoral to the infralittoral possibly due to changes in the water temperature and climatic conditions, that could influence the intertidal zone during the high and low tide, respectively. 相似文献
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V. R. Smith 《Oecologia》1978,32(2):239-253
Summary Manuring by the many seals and seabirds forms the major source of N and P to the Marion Island terrestrial ecosystem and plants at manured sites exhibit enhanced vitality and increased N and P contents in their leaf tissue and saps. A similar effect results from small applications of NPK fertilizer. Non-manured soils possess very low levels of available N but substantial quantities of organic N. 相似文献
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MARKES E. JOHNSON B. GUDVEIG BAARLI JAMES H. SCOTT Jr. 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1995,28(1):85-98
A low, rocky shoreline and attached abrasion platform of Late Pleistocene age are marked by a sharp disconformity within the Tamala Limestone Formation, exposed at Cape Burney facing the Indian Ocean near Geraldton, Western Australia. Colonization by an intertidal to shallow subtidal biota dominated by encrusting coralline red algae, oysters, and tube-dwelling worms occurs on a sandstone surface with a channeled topographic relief of 20–30 cm. The encrusting cup coral Rhizotrochus tuberculatus also is present, and this report details what is probably the first fossil occurrence of that species. The ancient rocky shore above this level retains trace fossils characteristic of a boring barnacle, probably belonging to Lithotrya. Herein named the Cape Burney sandstone, the distinctive unit on which the disconformity sits is assigned member status within the Tamala Limestone. Shell beds with a diversity of 35 species, dominated in volume by robust gastropods such as Turbo intercostalis and T. torquatus , thinly drape portions of the disconformity surface. Succeeding the shell drapes is a reef limestone with a maximum thickness of more than 2 m. The limestone is a massive accumulation of collapsed but otherwise mostly undisturbed coral fronds belonging primarily to a robust species of Acropora. Herein named the Bootenall limestone, this unit is assigned member status within the Tamala Limestone. Based on an analysis of electron spin resonance (ESR) from Acropora samples, the fringing reef developed between 120 ka and 132 ka, in the terminal stage of coastal transgression during the last interglacial period (Oxygen Isotope Substage 5e). □ Ancient rocky shores, intertidal abrasion platform, hard-substrate colonization, reef succession. 相似文献
19.
The effects of predators on the density of their prey can have positive indirect effects on the abundance of the preys resource via a trophic cascade. This concept has strongly influenced contemporary views of how communities are structured. However, predators also can transmit indirect effects by inducing changes in prey traits. We show that the mere presence of predator risk cues can initiate a trophic cascade in rocky shore tide pools. In large (mean surface area =9 m2), natural tide pools, we manipulated crab density and their foraging ability to examine the relative importance of lethal (density-mediated) and non-lethal (trait-mediated) predator effects to algal community development. We found that perceived predation risk reduced snail density as much as the direct predation treatment, showing that green crab predation was not an important factor regulating local snail density. Instead, snail emigration away from resident crabs appears to be the most important factor regulating local snail density. As a result, the abundance of ephemeral green algae was similar in the predation risk and direct predation treatments, suggesting that the consumption of snails by crabs plays a minimal role in mediating the trophic cascade. Increased attention to trait-mediated effects that are transmitted by predator-induced changes in prey behavior may change our view of how predators exert their strong influence on community structure. 相似文献
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Fourteen species of littoral Acari (Arachnida) were collected from the shores of sub-Antarctic Marion Island, of which Parasitiphis brunneus (Kramer) (Ologamasidae), Rhombognathus apsteini Lohmann and R. gressitti Newell (Halacaridae) are new to the Prince Edward Islands. Acari, impoverished both in terms of diversity and abundance, were confined to the few micro-habitats, including rocky-shore lichens, kelp holdfasts, other macroalgae and the surface pitting of mobile boulders, which provided protection from the direct and indirect stresses of severe wave action. 相似文献