The distribution of meiofauna on back‐reef sandy platforms in the Maldives (Indian Ocean)     

Federica Semprucci  Paolo Colantoni  Giuseppe Baldelli  Marco Rocchi  Maria Balsamo 《Marine Ecology》2010,31(4):592-607

The Maldivian archipelago comprises some of the most characteristic and significant world atoll systems, but the meiobenthic assemblages of these islands continue to be largely unknown. To investigate variations in meiofaunal spatial distribution and biodiversity in back‐reef platforms, three transects were studied, two at Felidhoo (the north and east sides) and one at South Malé. The sedimentological features of the samples obtained were also analyzed to further current knowledge on the relationships that exist between sediments and meiofauna. Our results reveal that the meiofaunal assemblage at these locations is well diversified and includes 20 major taxa. Nematodes and copepods are dominant, together forming 68% of the total meiofauna, followed by platyhelminthes, polychaetes and ostracods. The nematode assemblage is very rich and composed of 34 families and 123 genera – 96 of which (78%) set new records for the Maldives. The structures of the meiofaunal and nematode assemblages are relatively similar on the ‘large‐scale’ level (i.e. when the different platforms are compared) and reveal a low β‐diversity. However, significant dissimilarities were detected within each platform, emphasizing that such ‘small‐scale’ differences are the main factors determining the structure of the meiofauna and, in particular, the nematode assemblages. Although significant differences were not detected between the transects, greater levels of dissimilarity were recognized at North Felidhoo. Here, the building of inclined deposit layers plays a significant role in increasing the heterogeneity of the platform habitats and sediments, confirming the great importance of sediment granulometry as an environmental variable. Indeed, a close relationship is observed between meiofauna (especially for the nematodes) and grain size, which appears to control the structure, diversity and trophic composition of the Maldivian meiofauna assemblages, thus highlighting the high biodiversity existing in the medium‐coarse sands.  相似文献   

Marine reserves—the need for networks     

W. J. Ballantine 《新西兰海洋与淡水研究杂志》2013,47(1):115-116

Meiofauna associated with bryophyte and gravel habitats in two small alpine streams was investigated to determine its potential importance to stream communities. These invertebrates are traditionally neglected in stream surveys and their ecological roles poorly understood. Twenty‐one operational taxonomic units (OTUs) were found during the study, of which at least six were undescribed (two Copepoda and four Acarina). Meiofaunal densities were higher at the unshaded site than the shaded site, and higher within bryophyte than gravel habitats. Stepwise multiple regression analyses illustrated the importance of bryophytes to members of the meiofauna in each stream, and different meiofaunal communities were found associated with aquatic bryophytes and gravels. The high densities of Chironomidae, Nematoda, Copepoda, Tardigrada, and Rotifera associated with bryophytes may reflect the food value of the high periphyton biomass associated with these plants, and the shelter they offer from fast water currents. Although hyporheic meiofaunal taxa are known to move into interstices of mineral substratum for shelter, meiofauna associated with bryophytes dwell among stems and in leaf axils where they also find shelter. Because bryophyte‐dwelling meiofauna occur in very high densities, they probably play an important, if as yet unknown, role in energy transfer in streams.  相似文献   

Observations on Gastrotricha from a sandy beach in southeastern Australia,with a description of Halichaetonotus australis sp. nov. (Gastrotricha,Chaetonotida)     

Warwick Nicholas  M. Antonio Todaro 《新西兰海洋与淡水研究杂志》2013,47(4):973-980

Several species of Gastrotricha were found among samples of nematodes extracted from a sandy ocean beach, South Broulee beach, in southeastern Australia. One of these Gastrotricha turned out to be a species new to science which is described as Halichaetonotus australis sp. nov. in this study. Although the spines of the hydrofoil scales resemble those of the cosmopolitan H. aculifer, a distinctive feature of the new species is the presence of three prominent posterior dorsal spines. These are exaggerations of the keels found on the dorsal overlapping scales that cover the dorsal surfaces of the head, neck, and trunk. The spines are almost as long as the rami of the terminal furca. H. australis sp. nov. also resembles H. marivagus, but differs in lacking both a cephalion and hypostomion. Freeze drying is introduced as a preparation method for scanning electron microscopy of Gastrotricha.  相似文献   

A Simulation Model of a Deep Meiobenthic Compartment: A Preliminary Approach     

F. de  Bovee J. Ph.  Labat 《Marine Ecology》1993,14(2):159-173

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Influence of Introduced CO<Subscript>2</Subscript> on Deep-Sea Metazoan Meiofauna     

Kevin R. Carman  David Thistle  John W. Fleeger  James P. Barry 《Journal of Oceanography》2004,60(4):767-772

An experiment was performed to determine the effect of injected CO₂ on the deep-sea (3200 m) meiofaunal community in the Monterey Canyon. Approximately 20 L of liquid CO₂ was added to each of three cylindrical corrals (PVC rings pushed into the seabed) that were arranged in a triangular array 10 m on a side. After a 30-day period, sediment cores were collected within an area exposed to the dissolution plume emanating from the CO₂ pools and from a reference site approximately 40 m away; cores were also collected from within two of the CO₂ corrals. Sediment cores were sectioned into 0–5, 5–10, and 10–20 mm layers. Abundances of major groups (harpacticoid copepods, nematodes, nauplii, kinorhynchs, polychaetes, and total meiofauna) were determined for each layer. CO₂ exposure did not significantly influence the abundances or vertical distributions of any of the major taxa. However, other evidence suggests that abundance alone did not accurately reflect the effect of CO₂ on meiofauna. We argue that slow decomposition rates of meiofaunal carcasses can mask adverse effects of CO₂ and that longer experiments and/or careful examination of meiofaunal condition are needed to accurately evaluate CO₂ effects on deep-sea meiofaunal communities. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Do Harpacticoids (Copepoda) Use Water‐Borne Cues to Aid in Locating Food Parcels?     

Andrea Fechter  David Thistle  Günter Arlt  Keith Suderman  & Kay Vopel 《Marine Ecology》2004,25(3):217-223

Abstract.  Harpacticoid copepod food is patchily distributed and individuals must episodically move to new food patches. Key questions in harpacticoid feeding ecology include how individuals detect food patches and how rapidly they move toward patches. Based on literature reports, we hypothesized that harpacticoids locate food parcels by sensing a water-borne cue. We tested this idea using individuals of Leptastacus coulli Huys, 1992 and Praeleptomesochra similis Lang, 1965 from a sandy beach in north Florida (29.948° N, 84.341° W). Individuals from both species selected seawater that had been exposed to food significantly more frequently than they selected control seawater. The rate of movement of these species was millimeters per second, which agreed with previous reports.  相似文献   

Food and feeding habits of juvenile flounder Platichthys flesus (L.), abd turbot Scophthalmus maximus L. in the åland archipelago, northern Baltic Sea     

Katri Aarnio  Erik Bonsdorff  Nina Rosenback 《Journal of Sea Research》1996,36(3-4)

The food choice of juvenile flounder (Platichthys flesus) and turbot (Scophthalmus maximus) was studied in the northern Baltic Sea during the years 1988, 1989, 1994 and 1995. The diet included organisms from 30 species/taxa in flounder (n = 306) and 10 species/taxa in turbot (n = 41). Flounder 45 mm mainly consumed meiofauna (dominating taxon: Harpacticoida, Copepoda) and larger fish (46–101 mm) consumed macrofauna (dominating taxa: Oligochaeta, Amphipoda and Chironomidae). In terms of biomass, macrofauna dominated for all sizes of flounders, and meiofauna was important only for the smallest fish. A strong seasonal variation could be detected in the diet. In spring, macrofauna dominated for all size classes of fish (only fish > 30 mm were caught in spring), while in summer and autumn meiofauna dominated the diets for fish 45 mm in size. Juvenile turbot (22–88 mm) consumed macrofauna and small fish. Turbot 30 mm consumed mainly amphipods, while > 30 mm turbot consumed mysid shrimps, amphipods and fish.The ontogenetic shift from meio- to macrofauna-sized prey in flounders occurs at a larger fish size in the northern Baltic Sea than reported in other areas, possibly depending on the increased relative importance of meiofauna in the northern Baltic. The seasonal variation in the diet could be due to seasonally changing abundances in the zoobenthos, or for the small fish (1-group, spring), to switching from meio- to macrofauna in order to optimize their energy gain. The 0-group flounders consumed meiofauna for a long period, possibly due to a learning-process or simply due to easy availability of meiofauna. Turbot has a much larger mouth gap than flounders, thus allowing them to consume macrofauna from the beginning of their benthic life.  相似文献   

Community structure of epibenthic meiofauna in the St. Lucia Estuarine Lake (South Africa) during a drought phase     

D. Pillay  R. Perissinotto 《Estuarine, Coastal and Shelf Science》2009

The St. Lucia Estuary is Africa's largest estuarine system. It is a major component of the iSimangaliso (formerly Greater St. Lucia) Wetland Park, which was declared a World Heritage Site in 1999. The system has been severely affected by drought conditions which have culminated in the mouth of the system being cut off from the Indian Ocean since June 2002, for a period of almost five years. This study aimed to document the dynamics of meiofauna of the system during a drought phase, since (1) the effects of droughts on estuaries are poorly documented and understood and (2) because studies of meiofauna have never been undertaken in this system before. Meiofauna samples as well as physico-chemical data were collected at representative sites in February, April, August and October 2005. The drought had a major effect on the estuary, resulting in the development of hypersaline conditions (maximum 126 at Hells Gate), and to the complete evaporation of pelagic habitats, especially in the northern regions. The meiofauna of the St. Lucia Estuary was statistically separated into two distinct spatial clusters under drought conditions. The first cluster comprised sites in the Narrows and the southern region of South Lake, while the second comprised sites in the northern regions of South Lake and False Bay. Meiofauna of cluster 1, which was least affected by the drought, comprised nematodes, polychaetes, copepods, amphipods and ostracods, all of which accounted for 97% of meiofauna in this cluster. Cluster 2 on the other hand, which was more severely affected by the drought, was dominated by nematodes and copepods, which cumulatively contributed 97% to meiofauna in this group. Taxonomic richness and diversity of meiofauna were positively correlated with water depth, while abundance was inversely correlated with water temperature. The major effects of low water levels on the meiofauna of the system occurred through a negative impact on diversity and taxonomic richness, resulting in assemblages dominated by taxa most physiologically suited to such conditions. Secondly, at the peak of the drought, there was discontinuous water flow in the St. Lucia Estuary, resulting in parts of the northern and southern regions of the system being fragmented. This could have prevented the spread of meiofaunal taxa between the different basins of the system, and also explains the spatial separation of meiofauna into distinct clusters within the estuary.  相似文献   

厦门东海域和安海湾小型底栖动物的密度和生物量     

张玉红  王彦国  林荣澄  梁君荣  牛文涛  黄丁勇 《台湾海峡》2009,28(3):386-391

2007年6月对厦门东海域5个站位和晋江安海湾4个站位进行了小型底栖动物调查，分析了小型底栖动物的类群组成、密度和生物量．结果表明，从这两个海域样品中共鉴定出12个小型底栖动物类群，厦门东海域和安海湾自由生活海洋线虫分别占总数量的84．56％和98．19％．生物量组成和密度组成不同，厦门东海域多毛类（37．80％）、海洋线虫（33．32％）和底栖桡足类（18．64％）共同组成了小型底栖动物的生物量优势类群；安海湾生物量优势类群是由海洋线虫（67．64％）和多毛类（30．46％）组成．厦门东海域小型底栖动物的平均密度为72．67±10．21ind／cm^2，平均生物量为23．01±10．41μg/cm^2；安海湾的平均密度为31．48±45．58ind／cm^2，平均生物量为18．28±25．69μg/cm^2．  相似文献   

Diversity of meiofauna in the lacustrine profundal zone: Bathymetric differences and influence of environmental factors   总被引：2，自引：0，他引：2  

Jukka Särkkä 《Aquatic Sciences - Research Across Boundaries》1993,55(3):197-205

The diversity and species richness of total meiofauna, Harpacticoida and Oligochaeta in relation to depth and other environmental variables were studied at nine stations and in two profundal depth zones in Lake Päijänne which includes both oligotrophic and eutrophicated or organically loaded areas.Diversity was on average higher in the upper part of the profundal zone than at maximum depths. This may show that the greater temporal stability in temperature at greater depths does not surpass the effect of the lower temporal stability in oxygen content. The productivity factor may be a more important reason for the bathymetric difference in diversity than the stability factor. Diversity in the lower profundal zone shows a negative correlation with variables indicating pollution while in the upper profundal zone a positive one with those variables, thus emphasizing the importance of the production factor in determining diversity in the upper profundal. Diversity was higher within the oligochaetes than within the harpacticoids, which may imply that oligochaetes have a longer evolutionary history as part of the lacustrine benthic system.Of the environmental variables, phytoplankton biomass had the highest influence on total diversity in the lower profundal zone, oxygen being next in importance. The sedimentation of organic matter was most important in the upper part of the profundal zone, where oxygen did not have any significant effect on diversity. Some explaining factors determining bathymetric diversity differences are discussed in relation to the theoretical expectations.  相似文献