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  • 1
    Digitale Medien
    Digitale Medien
    Metabolic rate depression in a marine pulmonate snail: pre-adaptation for a terrestrial existence? (1991)
    Springer
    Oecologia 88 (1991), S. 274-276 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Limpets ; Intertidal ; Siphonaria ; Patella ; Metabolic rate depression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Terrestrial and freshwater pulmonate snails exhibit a marked depression of aerobic metabolism during estivation. This is an adaptation for existence in periodically harsh environments and, though marine gastropods may undergo anaerobic metabolism, they have not been shown to adaptively depress aerobic metabolic rate. We compared the metabolic response to progressive aerial exposure of two intertidal gastropod limpets, a prosobranch and a pulmonate. The prosobranch Patella granularis maintained a constant heart rate until shortly before death. In contrast, the pulmonate Siphonaria oculus underwent facultative depression of heart rate, accompanied by a decline in oxygen consumption. Both heart rate and oxygen consumption returned to normal levels on reimmersion in water. Metabolic rate depression is energy conserving, and may account for the ability of S. oculus to extend higher up the shore than P. granularis, into areas where food availability is low. S. oculus is a primitive, marine pulmonate, periodically subject to harsh conditions, and its capacity for metabolic rate depression may represent a pre-adaptation for life on land.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00320822
    Standort Signatur Einschränkungen Verfügbarkeit
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    Artikel (Nationallizenzen)
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  • 2
    Digitale Medien
    Digitale Medien
    Mutualism between the territorial intertidal limpet Patella longicosta and the crustose alga Ralfsia verrucosa (1993)
    Springer
    Oecologia 96 (1993), S. 128-133 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Territoriality ; Grazing ; Mutualism ; Limpet ; Intertidal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Mutualistic relations between plants and animals are well documented on land but have received less attention in marine systems. This study examined the relationship between the territorial intertidal limpet Patella longicosta and the crustose brown alga Ralfsia verrucosa. Adult Patella are found exclusively in association with Ralfsia, on which they feed, while Ralfsia occurs primarily, but not exclusively, in Patella territories. Ralfsia benefits directly from both the presence and the territorial behaviour of Patella. Algal productivity was assessed by measuring oxygen evolution and utilization in situ and deriving photosynthesis/irradiance curves. Productivity was increased by about 30% by the presence of Patella in both summer (P max of grazed algae 0.0098; ungrazed algae 0.0063 mg C · cm-2 · h-1) and winter (P max grazed algae 0.0081; ungrazed algae 0.0053 mg-2 · C · h-1). Algal growth rates were not significantly increased by the application of limpet mucus in the laboratory. We did not examine nutrient regeneration by the limpet, but the increase in photosynthetic rate may depend on the limpet's grazing pattern which creates secondary sites for growth. Ralfsia also benefited from the territorial behaviour of Patella. The effects of different grazing regimes were investigated in different seasons by removing territorial limpets and either excluding all limpets using copper-based antifouling paint, or allowing access to non-territorial limpets (mostly P. oculus) using partial paint barriers. Exclusion of all limpets resulted in rapid overgrowth of Ralfsia plants by the foliose green alga Ulva sp.. Where non-territorial limpets had access to the plants overgrowth was reduced but Ralfsia plants were entirely removed by destructive grazing. Non-territorial grazers removed 90% of Ralfsia plants within 4 weeks in summer and 60% in winter. In control treatments P. longicosta prevented overgrowth by Ulva and actively excluded vagrant grazers, preventing overgrazing. Based on these findings, the association between the limpet and alga can be regarded as a nonobligate mutualism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318040
    Standort Signatur Einschränkungen Verfügbarkeit
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    Artikel (Nationallizenzen)
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  • 3
    Digitale Medien
    Digitale Medien
    Enhancement of habitat heterogeneity and species richness on rocky shores inundated by sand (1990)
    Springer
    Oecologia 84 (1990), S. 142-144 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Rocky shores ; Sand inundation ; Species richness ; Habitat heterogeneity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Many rocky shores are subject to periodic inundation by sand, which is often thought to reduce species richness by eliminating organisms intolerant of sand scour or sand smothering. However, regular disturbance (e.g. inundation) should promote richness by preventing the development of low diversity climax communities. A study of faunal richness on 10 regularly inundated shores showed that inundation does promote richness, but by increasing habitat heterogeneity. Some species are excluded from parts of the shore by sand, but because of the patchiness of sand deposits they are rarely excluded from the entire shore. Other species are found only on rocks associated with sand, while typically sandy shore animals occur in the sand deposits themselves. Total richness (281 species) was greater than for local noninundated shores and sandy beaches combined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00665608
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    facet.materialart.
    Unbekannt
    Thermal specialization across large geographical scales predicts the resilience of mangrove crab populations to global warming (2014)
    In:  EPIC3Oikos, 124(6), pp. 784-795, ISSN: 00301299
    Details
    Publikationsdatum: 2017-06-15
    Beschreibung: The broad prediction that ectotherms will be more vulnerable to climate change in the tropics than in temperate regions includes assumptions about centre/edge population effects that can only be tested by within-species comparisons across wide latitudinal gradients. Here, we investigated the thermal vulnerability of two mangrove crab species, comparing populations at the centre (Kenya) and edge (South Africa) of their distributions. At the same time, we investigated the role of respiratory mode (water- versus air-breathing) in determining the thermal tolerance in amphibious organisms. To do this, we compared the vulnerability to acute temperature fluctuations of two sympatric species with two different lifestyle adaptations: the free living Perisesarma guttatum and the burrowing Uca urvillei, both pivotal to the ecosystem functioning of mangroves. The results revealed the air-breathing U. urvillei to be a thermal generalist with much higher thermal tolerances than P. guttatum. Importantly, however, we found that, while U. urvillei showed little difference between edge and centre populations, P. guttatum showed adaptation to local conditions. Equatorial populations had elevated tolerances to acute heat stress and mechanisms of partial thermoregulation, which make them less vulnerable to global warming than temperate conspecifics. The results reveal both the importance of respiratory mode to thermal tolerance and the unexpected potential for low latitude populations/species to endure a warming climate. The results also contribute to a conceptual model on the latitudinal thermal tolerance of these key species. This highlights the need for an integrated population-level approach to predict the consequences of climate change.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
  • 5
    facet.materialart.
    Unbekannt
    First oceanographic survey of the entire continental shelf adjacent to the northern Agulhas Current (2010)
    Academy of Science of South Africa
    In:  South African Journal of Science, 106 (9/10). pp. 7-9.
    Details
    Publikationsdatum: 2020-05-26
    Beschreibung: Reports on a major, multi-disciplinary cruise was organised to cover the full extent of the landward border of the northern Agulhas Current for the first time. This was done under the auspices of the African Coelacanth Ecosystem Programme as a South African contribution to the international Agulhas and Somali Current Large Marine Ecosystem.Reports on the cruise objectives, observations and some preliminary results.
    Materialart: Article , PeerReviewed
    Format: text
    DOI: 10.4102/sajs.v106i9/10.410
    Standort Signatur Einschränkungen Verfügbarkeit
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    OceanRep: Artikel in einer Fachzeitschrift - begutachtet
  • 6
    facet.materialart.
    Unbekannt
    Critical indirect effects of climate change on sub-Antarctic ecosystem functioning (2013)
    Wiley
    In:  Ecology and Evolution, 3 (9). pp. 2994-3004.
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: Sub-Antarctic islands represent critical breeding habitats for land-based top predators that dominate Southern Ocean food webs. Reproduction and molting incur high energetic demands that are sustained at the sub-Antarctic Prince Edward Islands (PEIs) by both inshore (phytoplankton blooms; "island mass effect"; autochthonous) and offshore (allochthonous) productivity. As the relative contributions of these sustenance pathways are, in turn, affected by oceanographic conditions around the PEIs, we address the consequences of climatically driven changes in the physical environment on this island ecosystem. We show that there has been a measurable long-term shift in the carbon isotope signatures of the benthos inhabiting the shallow shelf region of the PEIs, most likely reflecting a long-term decline in enhanced phytoplankton productivity at the islands in response to a climate-driven shift in the position of the sub-Antarctic Front. Our results indicate that regional climate change has affected the balance between allochthonous and autochthonous productivity at the PEIs. Over the last three decades, inshore-feeding top predators at the islands have shown a marked decrease in their population sizes. Conversely, population sizes of off-shore-feeding predators that forage over great distances from the islands have remained stable or increased, with one exception. Population decline of predators that rely heavily on organisms inhabiting the inshore region strongly suggest changes in prey availability, which are likely driven by factors such as fisheries impacts on some prey populations and shifts in competitive interactions among predators. In addition to these local factors, our analysis indicates that changes in prey availability may also result indirectly through regional climate change effects on the islands' marine ecosystem. Most importantly, our results indicate that a fundamental shift in the balance between allochthonous and autochthonous trophic pathways within this island ecosystem may be detected throughout the food web, demonstrating that the most powerful effects of climate change on marine systems may be indirect.
    Materialart: Article , PeerReviewed
    Format: text
    DOI: 10.1002/ece3.678
    Standort Signatur Einschränkungen Verfügbarkeit
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    OceanRep: Artikel in einer Fachzeitschrift - begutachtet
  • 7
    facet.materialart.
    Unbekannt
    Trophic ecology of Grey-headed albatrosses from Marion Island, Southern Ocean: insights from stomach contents and diet tracers (2010)
    Springer
    In:  Marine Biology, 157 (8). pp. 1755-1766.
    Details
    Publikationsdatum: 2021-08-24
    Beschreibung: During chick-rearing, albatrosses can alternate between long foraging trips that provide the main source of food for the adults and short foraging trips that they use to feed their young. This flexibility in foraging behaviour can lead to differences in diet composition between adults and chicks and implies that they may be vulnerable in different ways to food shortages. The trophic ecology of the Grey-headed albatross Thalassarche chrysostoma was investigated at the sub-Antarctic Prince Edward Islands during the chick-rearing period in April 2006 using a combination of approaches. Diets of adults and chicks were assessed using stable isotope ratios and fatty acid (FA) profiles of blood and/or stomach oils, in addition to stomach contents analysis. Fish from the family Macrouridae and cephalopods (particularly the onychoteuthid Kondakovia longimana) were the primary prey, whereas crustaceans (krill Euphausia superba) represented a smaller proportion of the stomach contents. Stomach oil FA profiles contained more monounsaturated FA than the profiles of plasma, which were richer in saturated FA and arachidonic acid (20:4n-6). There was also a distinct separation of adults from chicks, with higher levels of monounsaturates in chick plasma, and higher saturated FA levels (particularly 16:0) in the adult plasma. Stable carbon isotope ratios of whole blood were similar in adults and chicks, whereas stable nitrogen isotope ratios showed significant enrichment by 〉1‰ in chicks. The combined FA, stable isotopes and stomach contents analyses suggest clear differences in diet quality between adults and chicks, with chicks feeding at a higher trophic position through feeding more on highly nutritious fish and adults keeping much of the less nutritious zooplankton for themselves.
    Materialart: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00227-010-1448-y
    Standort Signatur Einschränkungen Verfügbarkeit
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    OceanRep: Artikel in einer Fachzeitschrift - begutachtet
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