Spatial Distribution and Biological Rhythms of Suprabenthic Mysids from the English Channel

1998 ◽  
Vol 78 (4) ◽  
pp. 1181-1202 ◽  
Author(s):  
Souaad Zouhiri ◽  
Carole Vallet ◽  
Pascal Mouny ◽  
Jean-Claude Dauvin
Keyword(s):  
Seasonal Cycle ◽  
Biological Rhythms ◽  
Swimming Activity ◽  
High Abundance ◽  
Seine Estuary ◽  
English Channel ◽  
Dominant Group ◽  
Medium Sand ◽  
Strong Activity ◽  
Sea Floor

One hundred and ninety-eight suprabenthic hauls from the English Channel and the Seine Estuary were taken with a modified Macer-GIROQ sledge. Numerically, mysids were the dominant group amongst the peracarids collected with the sledge and 28 species were recorded. Mysid densities were higher in the oligohaline zone (>200,000 ind 100 m-3) of the Seine Estuary than at other stations in the English Channel (where the density was the highest on medium sand stations, ~5000 ind 100 m-3). Two main gradients of mysid distribution were identified: (1) a higher species richness in the western part of the Channel compared with the eastern part of the Channel; and (2) an increasing density gradient from west to east during spring and a decreasing gradient from west to east during the autumn (eastern high abundance of Haplostylus spp. during spring, and western high abundance of Schistomysis ornata and Erythrops elegans during autumn). Mysids showed important diel rhythms with maximum abundance at sunrise and sunset, and low density at night. According to their swimming activities, suprabenthic mysids were classified into three groups: upper organisms with a very strong activity, species with a strong activity and occupying the whole water column near the sea-floor, and lower species with limited swimming activity. Nevertheless, the swimming activity could be modified according to the hydrodynamics of each site. A seasonal cycle of abundance (summer recruitment for dominant species Anchialina agilis, Haplostylus lobatus, Haplostylus normani) was observed on two stations where temporal samples along the year were available.

Distribution of benthic fauna in sediment grains and prop roots of a mangrove channel in south-eastern Brazil

2016 ◽  
Vol 97 (2) ◽  
pp. 377-385 ◽  
Author(s):  
Debora De Souza Silva-Camacho ◽  
Rafaela De S. Gomes ◽  
Joaquim N.S. Santos ◽  
Francisco Gerson Araújo
Keyword(s):  
Benthic Fauna ◽  
Fine Sand ◽  
Abundant Species ◽  
High Abundance ◽  
Dominant Group ◽  
Medium Sand ◽  
Spatial Partitioning ◽  
South Eastern ◽  
Eastern Brazil ◽  
Different Types

We examined the benthic fauna in four areas along a mangrove tidal channel in south-eastern Brazil, between October 2008 and August 2009. The tested hypothesis is that the most abundant groups avoid competition as they occupy different types of substrata and that the longitudinal distance from the sea also affects the occurrence of benthic fauna along the channel. We also examined the prop root epibiont fauna to describe this different community. Polychaeta was the dominant group in the sediment whereas Isopoda and Tanaidacea were the dominant groups on the prop roots. We found a tendency for higher infauna species richness and diversity in the innermost channel area during the summer. Higher abundance of epibiont fauna was also found in summer with tidal movements allowing the colonization of the prop roots of the mangrove forest by some taxa. The polychaetes Ceratocephale sp. and Laeonereis acuta had indication of habitat partitioning, with the first occurring mainly in very fine sand sediment whereas the latter preferred medium sand sediment. The microcrustaceans Chelorchestia darwini and Tanaidacea sp. 1 occurred in high abundance colonizing the prop roots. Exosphaeroma sp. was found in high abundance in infauna and epibiont fauna. The tested hypothesis of spatial partitioning of the mangrove channel by the benthic fauna was confirmed with the most abundant species occupying the substrata with different grain fractions and prop roots in different stations.

Macrobenthos of a Sublittoral Sandbank in the Southern Bight of the North Sea

1982 ◽  
Vol 62 (3) ◽  
pp. 521-534 ◽  
Author(s):  
C. Vanosmael ◽  
K. A. Willems ◽  
D. Claeys ◽  
M. Vincx ◽  
C. Heip
Keyword(s):  
North Sea ◽  
Tidal Currents ◽  
English Channel ◽  
Marine Transgression ◽  
Sea Floor ◽  
Southern Bight ◽  
Glacial Origin ◽  
The North ◽  
Belgian Coast ◽  
The North Sea

In the Southern Bight of the North Sea, off the Belgian coast, exists a series of parallel sublittoral sandbanks, the Flemish Banks, situated in a southwest-northeastern direction, 15–25 km long and 3–6 km wide. They are separated by channels, 4–6 km wide, and rise about 25 m above the surrounding sea-floor (Fig. 1). These sandbanks resulted from the accumulation of sandy deposits of glacial origin sedimented by the giant stream draining the waters from the present Rhine, Meuse, Scheldt and Thames before the Flandrian marine transgression about 12000 years ago. When from boreal times onwards the North Sea became slowly inundated, a connexion existed with the small English Channel which gradually enlarged, resulting in the very strong tidal currents which are responsible for the present geomorphology of the region.

The annual cycle of phytoplankton photosynthetic quantum efficiency, pigment composition and optical properties in the western English Channel

2004 ◽  
Vol 84 (2) ◽  
pp. 301-313 ◽  
Author(s):  
Jim Aiken ◽  
James Fishwick ◽  
Gerald Moore ◽  
Katharine Pemberton
Keyword(s):  
Quantum Efficiency ◽  
Nutrient Availability ◽  
Seasonal Cycle ◽  
Seasonal Pattern ◽  
Incident Light ◽  
Biological Properties ◽  
Linear Functions ◽  
Photon Flux ◽  
Bench Mark ◽  
English Channel

Phytoplankton photosynthetic quantum efficiency (PQE), pigments, absorption characteristics, species composition (converted to phytoplankton carbon, Cph) and other variables were measured at an offshore site in the western English Channel throughout 2001, using an opportunistic weekly sampling schedule. The variation of chlorophyll-a (Chla) and other phytoplankton pigments followed the classical seasonal cycle, driven by incident light, patterns of stratification and nutrient availability. Phytoplankton and pigment concentrations were low in the winter, rising to a peak in the spring ‘bloom’, with episodic blooms throughout the summer, an autumn bloom and a decline to the winter minimum. Surface layer Chla and total pigment (Tpig) concentrations were highly correlated for the whole year, yet it was observed that the fraction of Chla in Tpig (Chla/Tpig) was not constant and had a distinct seasonal pattern, low in winter and higher in spring, summer and autumn blooms. Chlorophyll-a/Tpig was linearly correlated with recent ambient light fluxes and maximum PQE (PQEm) throughout most of the year, though more significantly within seasonal periods. Chlorophyll-a and Tpig were both linearly correlated to Cph and the Chla/Cph ratio was significantly correlated with both Chla/Tpig and PQEm. Also the optical absorption ratios, a674/a443 and a674/a490 were significantly correlated with PQE and Chla/Tpig, indicating probable optical signatures for these two parameters. The seasonal cycle of measurements of photosynthetic quantum efficiency provided a bench-mark against which all the photosynthetically-driven seasonal changes of biological properties can be understood, in terms of incident solar radiation and nutrient availability. We conclude that phytoplankton synthesize Chla preferentially to other pigments or carbon compounds in conditions beneficial to growth. The PQEm, the ratios of Chla/Tpig, Chla/Cph and a674/a443 are greater when plants are growing actively. In periods of nutrient sufficiency, PQEm, Chla/Tpig and a674/a443 are all linear functions of the mean total photon flux for the recent few days. Photosynthetically driven changes in Chla synthesis, cause observed changes of Chla/Tpig and Chla/Cph ratios.

scholarly journals A linear pattern on the sea floor and its interpretation

1959 ◽  
Vol 38 (2) ◽  
pp. 313-319 ◽  
Author(s):  
A. H. Stride
Keyword(s):  
Continental Shelf ◽  
North Sea ◽  
English Channel ◽  
Large Area ◽  
Sea Floor ◽  
Linear Pattern ◽  
Dutch Coast ◽  
The North ◽  
The North Sea ◽  
Tidal Streams

The redistribution of sediments by tidal streams has been demonstrated in a number of ways in the seas around Britain. For example, the numerous banks in the North Sea are elongated parallel to the streams, while the depth and position of certain channels are subject to such important changes in position that re-surveys have to be made each year or so (Robinson, 1956). In the same region the streams, reaching about a knot or more at the surface, have wrought a large area of sand floor into ridges normal to their path. Off the Dutch coast the grade of the sand (Jarke, 1956) decreases in their inferred direction of advance (Stride & Cartwright, 1958). Similar relief is found even at 90 fathoms near the edge of the continental shelf, at the western approaches to the English Channel (Cartwright & Stride, 1958). Pratje (1950) has shown that the occurrence and grade of loose sediment on the floor of the Channel as a whole is directly related to the velocity of the streams overhead.

A Model of PCB Bioaccumulation in the Sea Bass Food Web from the Seine Estuary (Eastern English Channel)

2001 ◽  
Vol 43 (7-12) ◽  
pp. 242-255 ◽  
Author(s):  
V. Loizeau ◽  
A. Abarnou ◽  
P. Cugier ◽  
A. Jaouen-Madoulet ◽  
A.-M. Le Guellec ◽  
...  
Keyword(s):  
Food Web ◽  
Sea Bass ◽  
Seine Estuary ◽  
English Channel

Sub-bottom infilled channels in an area of the eastern English Channel

1975 ◽  
Vol 279 (1288) ◽  
pp. 233-241 ◽  
Keyword(s):  
Sea Level ◽  
English Channel ◽  
Hydrographic Data ◽  
Sea Floor ◽  
Fluvial Erosion ◽  
Tidal Regime ◽  
The North ◽  
Sea Bed ◽  
Late Tertiary ◽  
River Valleys

Contouring of geophysical and hydrographic data obtained during a regional geological and geophysical reconnaisance programme has resulted in the discovery of an extensive system of narrow, steep-sided, sub-bottom infilled channels. These channels, which occur to the north of the Cherbourg Peninsula, are, to a certain extent, structurally and stratigraphically controlled by the Cretaceous and Jurassic age strata into which they are cut, and appear to be the remnants of earlier river valleys filled with locally derived bedded and unbedded sands, silts, flints, boulders, clays and gravels. The depth reached by this infilling material is variable, ranging up to 200 m below sea-bed. It is suggested that this system may have originated during late Tertiary (Miocene) and that during the Plio-Pleistocene, when sea level was lower, a combination of tidal scour and fluvial erosion entrenched the system into the exposed sea floor. The present tidal regime and the differing physical characteristics of the strata involved suggest that the present bathymetry is a result of tidal scour

Sign in / Sign up

Export Citation Format

Share Document