Influence of sediment transport on short-term recolonization by seamount infauna
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MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 123:163-175 (1995) - doi:10.3354/meps123163 Influence of sediment transport on short-term recolonization by seamount infauna Levin LA, DiBacco C Rates and mechanisms of infaunal recolonization in contrasting sediment transport regimes were examined by deploying hydrodynamically unbiased colonization trays at 2 sites ~2 km apart on the flat summit plain of Fieberling Guyot in the eastern Pacific Ocean. Both study sites experienced strong bottom currents and high shear velocity (mu* exceeding 1.0 cm s-1 daily). Macrofaunal recolonization of defaunated sediments on Fieberling Guyot was slow relative to observations in shallow-water sediments, but rapid compared to other unenriched deep-sea treatments. Microbial colonization was slower but macrofaunal colonization was faster at White Sand Swale (WSS, 585 m), where rippled foraminiferal sands migrate daily, than at Sea Pen Rim (SPR, 635 m), where the basaltic sands move infrequently. Total densities of macrofaunal colonizers at WSS were 31 and 75% of ambient after 7 wk and 6.4 mo, respectively; at SPR they were 6 and 49% of ambient, respectively. Over 3/4 of the colonists were polychaetes (predominantly hesionids and dorvilleids) and aplacophoran molluscs. Species richness of colonizers was comparable at SPR and WSS and did not differ substantially from ambient. Most of the species (91%) and individuals (95%) recovered in colonization trays were taxa present in background cores. However, only 25% of the taxa colonizing tray sediments occurred in trays at both WSS and SPR. Sessile species, carnivores and surface feeders were initially slow to appear in colonization trays, but after 6.4 mo, colonizer feeding modes, life habits and mobility patterns mirrored those in ambient sediments at WSS and SPR. Defaunated sediments were colonized by larvae, juveniles and adults at both sites. These experiments provide the first observations of infaunal colonization on seamounts, and in deep, high-energy settings. Passive bedload transport appears to be a dominant colonization mechanism in unstable foraminiferal sands at WSS. Based on the rapid recovery of infauna in trays and low diversity at WSS, we infer that disturbance is a natural feature of this site and that the ambient fauna of WSS retains features of early succession. Infaunal colonization is slower in the stable substrate at SPR, where physical disturbance may occur much less frequently. Colonization rates . Disturbance . Soft-bottom . Succession . Fieberling Guyot . High-energy regime . Macrofauna . Seamount . Sediment transport . Vertical distribution Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 123. Publication date: July 20, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.Keywords:
Seamount
Abyssal zone
Abyssal zone
Assemblage (archaeology)
Abyssal plain
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The abyssal seafloor makes up three quarters of the ocean floor, and it is generally characterized as a food-limited habitat with low numbers of megafauna, particularly fishes. Baited camera observations from three abyssal seamount summits in the equatorial Pacific challenge this idea. On each of two deployments at the southernmost seamount, over 100 synaphobranchid eels (Ilyophis arx) were recorded feeding on standard bait (1 kg mackerel). This is the highest number of fishes per kg of bait ever recorded below 1000 m, including observations from large organic falls such as cetacean and shark carcasses. It is also the highest number that has ever been recorded at carrion of any kind or size at abyssal depths. We suggest an abyssal 'seamount effect' may be responsible, highlighting the potential importance of seamounts in structuring abyssal communities.
Seamount
Abyssal zone
Megafauna
Abyssal plain
Seabed
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Seamounts are common in all ocean basins, and most have summit depths >3,000 m. Nonetheless, these abyssal seamounts are the least sampled and understood seamount habitats. We report bait-attending community results from the first baited camera deployments on abyssal seamounts. Observations were made in the Clarion Clipperton Zone (CCZ), a manganese nodule region stretching from south of Hawaii nearly to Mexico. This zone is one of the main target areas for (potential) large-scale deep-sea nodule mining in the very near future. The Seamount Refuge Hypothesis (SRH) posits that the seamounts found throughout the CCZ provide refugia for abyssal fauna likely to be disturbed by seabed mining, yielding potential source populations for recolonization of mined areas. Here we use baited cameras to test a prediction of this hypothesis, specifically that predator and scavenger communities are shared between abyssal seamounts and nearby abyssal plains. We deployed two camera systems on three abyssal seamounts and their surrounding abyssal plains in three different Areas of Particular Environmental Interests (APEIs), designated by the International Seabed Authority as no-mining areas. We found that seamounts have a distinct community, and differences in community compositions were driven largely by habitat type and productivity changes. In fact, community structures of abyssal-plain deployments hundreds of kilometers apart were more similar to each other than to deployments ∼15 km away on seamounts. Seamount communities were found to have higher morphospecies richness and lower evenness than abyssal plains due to high dominance by synaphobranchid eels or penaeid shrimps. Relative abundances were generally higher on seamounts than on the plains, but this effect varied significantly among the taxa. Seven morphotypes were exclusive to the seamounts, including the most abundant morphospecies, the cutthroat eel Ilyophis arx. No morphotype was exclusive to the abyssal plains; thus, we cannot reject the SRH for much of the mobile megafaunal predator/scavenging fauna from CCZ abyssal plains. However, the very small area of abyssal seamounts compared to abyssal plains suggest that seamounts are likely to provide limited source populations for recolonizing abyssal plains post-mining disturbance. Because seamounts have unique community compositions, including a substantial number of predator and scavenger morphospecies not found on abyssal plains, they contribute to the beta biodiversity of the Clarion-Clipperton Zone, and thus indirect mining impacts on those distinct communities are of concern.
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Abyssal zone
Abyssal plain
Seabed
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Summary The polychaete Iphitime cuenoti was found inhabiting the branchial chamber of the spider crab Macropodia longirostris in the Isle of Man area. The species of Iphitime and previous records of their occurrence are summarised. The sexual dimorphism of the polychaete is discussed, and its mode of nutrition and relations with its host considered. Ophryotrocha geryonicola, another polychaete inhabiting the branchial chamber of decapods, is compared with Iphitime.
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The accumulative impact of the intensive scallop culture on the bottom environment and polychaete community structure were studied in Saroma Lagoon , northern Japan . The bottom sampling was carried out in 1995, and the multivariate analysis have been used to compare 1975, 1987 data with 1995 data. 55 species were identified in 1995 samples, among them the dominant species were Maldane cristata, Lumbrineris longifolia and Scalibregma inflatum , which were typical species in Japanese eutrophic coastal bays . The result of comparative analysis of the polychaete community structure during period of the past 20 years showed marked changes in species number , density and species composition . The species composition of polychaete community in 1995 indicates that the lagoon environment may not be in the state of heavily organic pollution. But clear temporal changes in the community structure and frequent occurrence of spreading hypoxic water and red tides in recent time suggest the accumulative organic loading by the intensive scallop culture in the lagoon may cause severe bottom hypoxia, eutrophication of water and stressful disturbances to the benthic community.
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Seamount
Oceanic basin
Fracture zone
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Abyssal zone
Abyssal plain
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The deep ocean greater than 1 km covers the majority of the earth's surface. Interspersed on the abyssal plains and continental slope are an estimated 14000 seamounts, topographic features extending 1000 m off the seafloor. A variety of hypotheses are posited that suggest the ecological, evolutionary, and oceanographic processes on seamounts differ from those governing the surrounding deep sea. The most prominent and oldest of these hypotheses, the seamount endemicity hypothesis (SMEH), states that seamounts possess a set of isolating mechanisms that produce highly endemic faunas. Here, we constructed a faunal inventory for Davidson Seamount, the first bathymetric feature to be characterized as a 'seamount', residing 120 km off the central California coast in approximately 3600 m of water (Fig 1). We find little support for the SMEH among megafauna of a Northeast Pacific seamount; instead, finding an assemblage of species that also occurs on adjacent continental margins. A large percentage of these species are also cosmopolitan with ranges extending over much of the Pacific Ocean Basin. Despite the similarity in composition between the seamount and non-seamount communities, we provide preliminary evidence that seamount communities may be structured differently and potentially serve as source of larvae for suboptimal, non-seamount habitats.
Seamount
Abyssal plain
Abyssal zone
Bathyal zone
Seafloor Spreading
Oceanic basin
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