Suprabenthic crustacean fauna of a denseAmpeliscacommunity from the English Channel

1996 ◽  
Vol 76 (4) ◽  
pp. 909-929 ◽  
Author(s):  
Jean-Claude Dauvin ◽  
Souaad Zouhiri
Keyword(s):  
Atlantic Ocean ◽  
Water Column ◽  
Vertical Migration ◽  
Fine Sand ◽  
Abundant Species ◽  
Sexually Dimorphic ◽  
English Channel ◽  
Free Swimming ◽  
Sea Bottom ◽  
Sea Bed

Ninety-six species (97, 677individuals) were collected over the course of 6 h in five suprabenthic sledge hauls from a very denseAmpeliscafine sand community from the Bay of Morlaix (western English Channel). All the species migrated into the water column at night (98% of the specimens collected in the suprabenthos were found in the night hauls). The 23 most abundant species collected were classified into five groups based on their height within the water column, but two groups predominated: the upper suprabenthic species, abundant at 0–80–145 m above the sea-bed; and the lower suprabenthic species which were abundant only near the sea bottom (-0–1–0–75 m high). Three different patterns of nocturnal vertical migration were distinguished based on the timing of maximum swimming activity: at dusk; at the beginning of the night; or later in the night. Sexually dimorphic patterns of free-swimming behaviour was observed inAmpeliscaand some other species of Amphipoda (Bathyporeia teniupes, Metaphoxusfultoni), and Cumacea (Bodotria pulchella, Pseudocuma longicornis), with many more males than females migrating into the water column at night. Finally, the density of suprabenthic crustaceans in nocturnal hauls was amongst the highest reported from infralittoral or circalittoral suprabenthic studies on other parts of the Atlantic Ocean sampled during spring.

Sexually Dimorphic Free-Swimming Behaviour in the Amphipod Crustacean Ampelisca Abdita

1991 ◽  
Vol 71 (3) ◽  
pp. 655-663 ◽  
Author(s):  
B. Borowsky ◽  
P. Aitken
Keyword(s):  
Water Column ◽  
Swimming Behaviour ◽  
Sexually Dimorphic ◽  
Free Swimming ◽  
Amphipod Crustacean ◽  
Males And Females

This paper describes a novel sexually dimorphic pattern of behaviour in the tube-building amphiplodAmpelisca abdita (Mills). Mature males and females enter the water column at night. However, while males enter the water column every night, females enter it only when they moult. Since female amphipods only mate shortly after they moult, it is hypothesized that this sexually dimorphic pattern of free-swimming behaviour is an adaptation that permits males and receptive females to locale each other during the brief period when copulation can occur, while reducing the time that females are exposed to pelagic predators.

scholarly journals The Dredgings of the Marine Biological Association (1895–1906), as a Contribution to the Knowledge of the Geology of the English Channel

1908 ◽  
Vol 8 (2) ◽  
pp. 118-188 ◽  
Author(s):  
R. Hansford Worth
Keyword(s):  
English Channel ◽  
Geological Society ◽  
Coast Line ◽  
Biological Association ◽  
Marine Biological ◽  
Marine Biological Association ◽  
Sea Bottom ◽  
Sea Bed ◽  
Coastal Deposits ◽  
Chief Interest

Investigation of the geologic problems connected with the English Channel is no new matter. Setting aside all speculations deriving from the study of its coast-line, the first serious examination of the bed of the Channel was made by R. A. C. Austen, and his results published in the Proceedings of the Geological Society, 13 June, 1849. Although, as he states, he had examined the sea-bed with dredge and sounding-lead he has little to say as to its lithology. But none the less his work is a notable contribution to our knowledge, and his conclusions bear well the test of subsequent discoveries. Following Austen, in 1871, Delesse published his Lithologie des Mers de France, in which considerable attention is given to the Channel; and the lithology of its coastal deposits, and to some extent of the sea-bed, is considered in detail. But, valuable as this work is, its chief interest lies in the information given as to the nature of the sea-bottom, the grade and extent of the varying deposits. Austen and Delesse alike, and in agreement, point out the large areas of the Channel bed which are occupied by stones, boulders, and pebbles of some size, and argue on much the same lines as to the conditions which have formerly existed there.

Effect of extremely severe winters on under-ice phytoplankton development in a mesotrophic lake (Eastern Poland)

2014 ◽  
Vol 43 (2) ◽  
Author(s):  
Władysława Wojciechowska ◽  
Tomasz Lenard
Keyword(s):  
Water Column ◽  
Dominant Species ◽  
Biomass Concentration ◽  
Thermal Conditions ◽  
Ice Cover ◽  
Abundant Species ◽  
Blue Green Algae ◽  
Cyanobacteria And Algae ◽  
Taxonomic Groups ◽  
The Vertical Distribution

AbstractThe research was carried out in a mesotrophic and dimictic lake during winters with ice cover. In the last forty years, the development of phytoplankton was analyzed in five extreme winter seasons. The studies of phytoplankton characteristics in the water column took into account values of biomass, concentration of chlorophyll-a and species composition, including dominant species. Differences in the vertical distribution of flagellate and non-flagellate species belonging to cyanobacteria and algae were analyzed in the gradient of light and thermal conditions. The phytoplankton biomass was low and vertically differentiated, with the lowest values at the deeper part of the water column. Flagellate species from the group of Cryptophyceae, Chrysophyceae and Dinophyceae were most abundant. Species biodiversity was low but every winter the dominant species represented different taxonomic groups. In some periods, larger non-motile phytoplankton species from green or blue-green algae dominated. The research proved that the development of phytoplankton under the ice cover was limited mainly by light and, to a lesser extent, by temperature.

An Investigation Into the Non-Linear Effects Resulting From Air Cushions in the Orecon Oscillating Water Column (OWC) Device

2009 ◽  
Author(s):  
Jim L. Lye ◽  
David T. Brown ◽  
Fraser Johnson
Keyword(s):  
Water Column ◽  
Mooring Line ◽  
Oscillating Water Column ◽  
Trapped Air ◽  
Model Scale ◽  
Sea Bed ◽  
Structural Responses ◽  
Linear Effects ◽  
The Waves ◽  
Base Structure

When designing an Oscillating Water Column (OWC) device, the motions and structural responses in waves are of great interest. However, predictions of these motions are complicated by the presence of air chambers above a large proportion of the waterplane area. Modeling the stiffness provided by air cushions at model scale presents a number of problems as air stiffness does not scale according to the laws of Froude scaling. To-date, the closest analogy might be an air-lifted gravity base structure, or crane vessel. However, in an OWC device, the air is not trapped as it is allowed to vent through a turbine. As a result, in still water, none of the mass of the buoy is supported by the air column. However, as the buoy is subjected to waves of increasing height the influence of the air chambers on the motions response becomes more pronounced. Experiments into the behavior of structures with trapped air springs have focused largely on benign sea conditions as the air cushions are generally used in vessels or structures involved with installation operations or similar. In contrast, the behavior of an OWC device must be predicted in all conditions up to, and including, survival conditions. BPP-TECH are providing technical support to the designers of the Orecon MRC wave energy buoy. This buoy uses chambers of varying drafts to generate electricity from the waves. The buoy is tension moored to the sea bed in order to constrain the heave motions to maximize the air pressure within the chambers as waves pass. A series of tank tests were undertaken at the OCEANIDE facility in order to investigate the motions of the buoy while tension moored and also measure the mooring line tensions. This paper will focus on the methods used to represent the air chambers at model scale and will present the results of the tests. A variety of different orifice sizes were used in the test campaign in order to provide a spread of values that would offer an insight into the effect of the air chambers on the motions of the structure in waves.

Contribution of Gammarus lacustris to phosphorus recycling in a fishless alpine lake

1999 ◽  
Vol 56 (9) ◽  
pp. 1679-1686 ◽  
Author(s):  
Frank M Wilhelm ◽  
Jeff J Hudson ◽  
David W Schindler
Keyword(s):  
Water Column ◽  
Vertical Migration ◽  
Mountain Lakes ◽  
Plankton Community ◽  
Alpine Lake ◽  
Gammarus Lacustris ◽  
Benthic Pelagic Coupling ◽  
Phosphorus Recycling ◽  
Planktonic Community ◽  
Total P

We estimated the net P transport by Gammarus lacustris from the benthic to pelagic regions of a fishless alpine lake and compared it with P regeneration by the entire plankton community. Gammarus lacustris released between 5.2 and 18.1 ng P·L-1·h-1 (adults only and adults plus immatures, respectively) in the pelagic region during nighttime vertical migration. Additional P released into and removed from the water column due to predation on zooplankton was estimated at 1.87 and 2.3 ng P·L-1·h-1, respectively. The net daily regeneration of 52.2-181.4 ng P·L-1·day-1 by the G. lacustris population represented 9.5-32.9% of the total P regenerated by the planktonic community. The majority of the P released by G. lacustris represents "new" P to the pelagic zone because it originated in sediments. We conclude that G. lacustris can represent an important link in benthic-pelagic coupling in oligotrophic mountain lakes.

scholarly journals A quest for the biological sources of long chain alkyl diols in the western tropical North Atlantic Ocean

2018 ◽  
Vol 15 (19) ◽  
pp. 5951-5968 ◽  
Author(s):  
Sergio Balzano ◽  
Julie Lattaud ◽  
Laura Villanueva ◽  
Sebastiaan W. Rampen ◽  
Corina P. D. Brussaard ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Water Column ◽  
North Atlantic ◽  
18S Rrna ◽  
North Atlantic Ocean ◽  
18S Rrna Gene ◽  
Rrna Gene ◽  
Tropical North Atlantic ◽  
Biological Sources ◽  
Long Chain

Abstract. Long chain alkyl diols (LCDs) are widespread in the marine water column and sediments, but their biological sources are mostly unknown. Here we combine lipid analyses with 18S rRNA gene amplicon sequencing on suspended particulate matter (SPM) collected in the photic zone of the western tropical North Atlantic Ocean at 24 stations to infer relationships between LCDs and potential LCD producers. The C30 1,15-diol was detected in all SPM samples and accounted for >95 % of the total LCDs, while minor proportions of C28 and C30 1,13-diols, C28 and C30 1,14-diols, as well as C32 1,15-diol were found. The concentration of the C30 and C32 diols was higher in the mixed layer of the water column compared to the deep chlorophyll maximum (DCM), whereas concentrations of C28 diols were comparable. Sequencing analyses revealed extremely low contributions (≈0.1 % of the 18S rRNA gene reads) of known LCD producers, but the contributions from two taxonomic classes with which known producers are affiliated, i.e. Dictyochophyceae and Chrysophyceae, followed a trend similar to that of the concentrations of C30 and C32 diols. Statistical analyses indicated that the abundance of 4 operational taxonomic units (OTUs) of the Chrysophyceae and Dictyochophyceae, along with 23 OTUs falling into other phylogenetic groups, were weakly (r≤0.6) but significantly (p value <0.01) correlated with C30 diol concentrations. It is not clear whether some of these OTUs might indeed correspond to C28−32 diol producers or whether these correlations are just indirect and the occurrence of C30 diols and specific OTUs in the same samples might be driven by other environmental conditions. Moreover, primer mismatches were unlikely, but cannot be excluded, and the variable number of rRNA gene copies within eukaryotes might have affected the analyses leading to LCD producers being undetected or undersampled. Furthermore, based on the average LCD content measured in cultivated LCD-producing algae, the detected concentrations of LCDs in SPM are too high to be explained by the abundances of the suspected LCD-producing OTUs. This is likely explained by the slower degradation of LCDs compared to DNA in the oxic water column and suggests that some of the LCDs found here were likely to be associated with suspended debris, while the DNA from the related LCD producers had been already fully degraded. This suggests that care should be taken in constraining biological sources of relatively stable biomarker lipids by quantitative comparisons of DNA and lipid abundances.

scholarly journals Patterns of distribution and abundance of larval phosichthyidae (actinopterygii, stomiiformes) in southeastern Brazilian waters

2011 ◽  
Vol 59 (3) ◽  
pp. 213-229 ◽  
Author(s):  
Cássia Gôngora Goçalo ◽  
Mario Katsuragawa ◽  
Ilson Carlos Almeida da Silveira
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Distribution Patterns ◽  
Southeastern Brazil ◽  
Patterns Of Distribution ◽  
Oceanic Region ◽  
Brazil Current ◽  
Horizontal And Vertical Distribution

Horizontal and vertical distribution patterns and abundance of larval phosichthyids were investigated from oblique and depth-stratified towns off Southeastern brazilian waters, from São Tomé cape (41ºW.; 22ºS.) to São Sebastião island (45ºW.; 24ºS.). The sampling was performed during two cruises (January/2002 -summer; August/2002 -winter). Overall 538 larvae of Phosichthyidae were collected during summer and 158 in the winter. Three species, Pollichthys mauli, Vinciguerria nimbaria and Ichthyioccoccus sp. occurred in the area, but Ichthyioccoccus sp. was extremely rare represented by only one specimen, caught in the oceanic region during the summer. Geographically, larval were concentrated in the oceanic region, and vertically distributed mainly between the surface and 80 m depth in the summer and winter. Larvae were more abundant during the night, performing a diel vertical migration in the water column. The results suggest that the meandering and eddies of Brazil Current play important role on the transport and distribution patterns of larval phosichthyids over the oceanic and neritic area in the Southeastern Brazil.

scholarly journals Uncertainties of particulate organic carbon concentrations in the mesopelagic zone of the Atlantic ocean

2021 ◽  
Vol 1 ◽  
pp. 43
Author(s):  
Paul Strubinger Sandoval ◽  
Giorgio Dall'Olmo ◽  
Keith Haines ◽  
Rafael Rasse ◽  
Jelizaveta Ross
Keyword(s):  
Organic Carbon ◽  
Atlantic Ocean ◽  
Water Column ◽  
Carbon Cycling ◽  
Particulate Organic Carbon ◽  
Sea Surface ◽  
Mesopelagic Zone ◽  
Potential Sources ◽  
Oceanic Carbon ◽  
Carbon Concentrations

Measurements of particulate organic carbon (POC) in the open ocean provide grounds for estimating oceanic carbon budgets and for modelling carbon cycling. The majority of the published POC measurements have been collected at the sea surface. Thus, POC stocks in the upper layer of the water column are relatively well constrained. However, our understanding of the POC distribution and its dynamics in deeper areas is modest due to insufficient in POC measurements. Moreover, the accuracy of published POC estimates is not always quantified, and neither is it fully understood. In this study, we determined the POC concentrations of samples collected in the upper 500 m during an Atlantic Meridional Transect and described a method for quantifying its experimental uncertainties using duplicate measurements. The analysis revealed that the medians of the total experimental uncertainties associated with our POC concentrations in the productive and mesopelagic zones were 2.5(±1.2) mg/m3 and 2.6(±0.6) mg/m3, respectively. In relative terms, these uncertainties corresponded to ~14% and ~ 35% of POC concentrations, respectively. However, despite our best efforts, we could explain only ~ 21% of the total experimental POC uncertainty. The potential sources of this unexplained portion of uncertainty are discussed.

scholarly journals Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 349 ◽  
Author(s):  
Mariana Benites ◽  
James R. Hein ◽  
Kira Mizell ◽  
Terrence Blackburn ◽  
Luigi Jovane
Keyword(s):  
Atlantic Ocean ◽  
Shallow Water ◽  
Water Column ◽  
Rio Grande ◽  
Intermediate Water ◽  
Mode Water ◽  
Southwest Atlantic ◽  
Ferromanganese Crusts ◽  
Depositional Processes ◽  
Water Depths

The Rio Grande Rise (RGR) is a large elevation in the Atlantic Ocean and known to host potential mineral resources of ferromanganese crusts (Fe–Mn), but no investigation into their general characteristics have been made in detail. Here, we investigate the chemical and mineralogical composition, growth rates and ages of initiation, and phosphatization of relatively shallow-water (650–825 m) Fe–Mn crusts dredged from the summit of RGR by using computed tomography, X-ray diffraction, 87Sr/86Sr ratios, U–Th isotopes, and various analytical techniques to determine their chemical composition. Fe–Mn crusts from RGR have two distinct generations. The older one has an estimated age of initiation around 48–55 Ma and was extensively affected by post-depositional processes under suboxic conditions resulting in phosphatization during the Miocene (from 20 to 6.8 Ma). As a result, the older generation shows characteristics of diagenetic Fe–Mn deposits, such as low Fe/Mn ratios (mean 0.52), high Mn, Ni, and Li contents and the presence of a 10 Å phyllomanganate, combined with the highest P content among crusts (up to 7.7 wt %). The younger generation is typical of hydrogenetic crusts formed under oxic conditions, with a mean Fe/Mn ratio of 0.75 and mean Co content of 0.66 wt %, and has the highest mean contents of Bi, Nb, Ni, Te, Rh, Ru, and Pt among crusts formed elsewhere. The regeneration of nutrients from local biological productivity in the water column is the main source of metals to crusts, providing mainly metals that regenerate rapidly in the water column and are made available at relatively shallow water depths (Ni, As, V, and Cd), at the expense of metals of slower regeneration (Si and Cu). Additionally, important contributions of nutrients may derive from various water masses, especially the South Atlantic Mode Water and Antarctic Intermediate Water (AAIW). Bulk Fe–Mn crusts from the summit of RGR plateau are generally depleted in metals considered of greatest economic interest in crusts like Co, REE, Mo, Te, and Zr, but are the most enriched in the critical metals Ni and Li compared to other crusts. Further investigations are warranted on Fe–Mn crusts from deeper-water depths along the RGR plateau and surrounding areas, which would less likely be affected by phosphatization.

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