Benthic Communities Associated With a Heavily Fished Scallop Ground in the English Channel

1998 ◽  
Vol 78 (4) ◽  
pp. 1045-1059 ◽  
Author(s):  
M.J. Kaiser ◽  
P.J. Armstrong ◽  
P.J. Dare ◽  
R.P. Flatt
Keyword(s):  
Acoustic Signal ◽  
Benthic Communities ◽  
Sandy Sediment ◽  
English Channel ◽  
Muddy Sand ◽  
Faunal Assemblages ◽  
Large Size ◽  
Suitable Habitats ◽  
Sandy Sediments ◽  
Sand Sediments

A survey of benthic communities found in a heavily fished scallop ground was undertaken in July 1993. Two main faunal assemblages were identified from samples obtained with fine-meshed scallop dredges, which were grouped either in gravelly sand sediments or sandy sediment, which was generally furthest offshore in deeper water. A third assemblage was found in either sandy or gravelly muddy sand sediments. The highest abundance of small and large size-classes of scallops were associated with the assemblage containing the greatest number of species and individuals in sandy sediments. This assemblage had the greatest biomass of emergent fauna such as hydroids and Alcyonium digitatum. Data acquired from a RoxAnn™ acoustic signal processor were able to differentiate between the substratum or biotopes associated with the greatest abundance of scallops. This may provide a useful tool for refining surveys of commercial stocks or mapping suitable habitats.

scholarly journals MỐI QUAN HỆ GIỮA ĐỘNG VẬT ĐÁY CÓ GIÁ TRỊ KINH TẾ CHỦ YẾU VỚI ĐẶC TRƯNG SINH THÁI CỦA ĐẦM THỊ NẠI, VIỆT NAM

2019 ◽  
Vol 19 (1) ◽  
pp. 127-135
Author(s):  
Phan Duc Ngai ◽  
Vo Si Tuan
Keyword(s):  
Economic Value ◽  
Scientific Basis ◽  
Viet Nam ◽  
Sandy Sediment ◽  
Bivalve Species ◽  
Muddy Sand ◽  
Benthic Animal ◽  
Fisheries Resources ◽  
Commercial Yield ◽  
Sand Sediments

Relations between economic zoobenthos species and ecological characteristics of Thi Nai lagoon were reported as results of three surveys carried out during 2014–2015. The results have pointed out 11 zoobenthos species that have primarily economic value at the Thi Nai lagoon (5 bivalve species, 5 crustacea species and 1 gastropoda species). Bivalve group possesses 91% of the entire commercial yield of benthic animal (7,456.9 tons/year), in which Glauconome chinensis and Gari elongata possess dominatingly (possess 90% of the entire commercial yield of bivalves: 6,817 tons/year). Bivalve and gastropoda groups were found in correlation with sandy sediment and mangroves but crustacea group was found in correlation with muddy sand sediments and seagrass. The results of this study will conntribute the scientific basis for further studies on the trophic relationship, food web and data for planning, zoning and appropriate exploitation of fisheries resources.

The frequency of butchery marks on goat (Capra hircus) remains from pastoral Khoekhoe villages at Gobabeb, Namibia

Indago ◽  
2020 ◽  
Vol 36 ◽  
pp. 1-12
Author(s):  
Shaw Badenhorst ◽  
Jackson S. Kimambo
Keyword(s):  
South Africa ◽  
Iron Age ◽  
Skeletal Remains ◽  
River Valley ◽  
Capra Hircus ◽  
Faunal Assemblages ◽  
Large Size ◽  
Middle Iron Age

Khoekhoe pastoralists living in Gobabeb, in the arid Kuiseb River Valley of central-western Namibia, keep goats (Capra hircus). Several decades ago, palaeontologist C.K. Brain collected modern skeletal remains of goats from these villages. The goats were butchered using pocketknives with metal blades. We investigated the frequency of butchery marks on a sub-sam- ple of this collection, representing 60% of the total assemblage. Most specimens in the collection are weathered. Moreover, most goat specimens from Gobabeb lack butchery evidence and even the use of magnification only marginally increased this number. We compared our results with the frequency of butchery marks documented from Early and Middle Iron Age samples from South Africa, a time when sheep dominated faunal assemblages and were slaughtered using metal knives. The frequency of specimens with butchery marks in the goat sample from Gobabeb is higher than that recorded for the Early and Middle Iron Age samples. The higher frequency of butchery marks on the goat remains from Gobabeb may relate to aspects such as the butchering method and style, as well as the large size of the specimens themselves.

scholarly journals Uncovering the environmental drivers of short-term temporal dynamics in an epibenthic community from the Western English Channel

2019 ◽  
Vol 99 (7) ◽  
pp. 1467-1479
Author(s):  
Elizabeth Talbot ◽  
Jorn Bruggeman ◽  
Chris Hauton ◽  
Stephen Widdicombe
Keyword(s):  
Time Series Data ◽  
Temporal Dynamics ◽  
Anthropogenic Impacts ◽  
Benthic Communities ◽  
Food Limitation ◽  
Environmental Drivers ◽  
Sediment Surface ◽  
Series Data ◽  
English Channel ◽  
Larval Recruitment

AbstractBenthic communities, critical to the health and function of marine ecosystems, are under increasing pressure from anthropogenic impacts such as pollution, eutrophication and climate change. In order to refine predictions of likely future changes in benthic communities resulting from these impacts, we must first better constrain their responses to natural seasonality in environmental conditions. Epibenthic time series data (July 2008–May 2014) have been collected from Station L4, situated 7.25 nautical miles south of Plymouth in the Western English Channel. These data were analysed to establish patterns in community abundance, wet biomass and composition, and to link any observed patterns to environmental variables. A clear response to the input of organic material from phytoplankton blooms was detected, with sediment surface living deposit feeders showing an immediate increase in abundance, while predators and scavengers responded later, with an increase in biomass. We suggest that this response is a result of two factors. The low organic content of the L4 sediment results in food limitation of the community, and the mild winter/early spring bottom water temperatures allow the benthos to take immediate advantage of bloom sedimentation. An inter-annual change in community composition was also detected, as the community shifted from one dominated by the anomuran Anapagurus laevis to one dominated by the gastropod Turitella communis. This appeared to be related to a period of high larval recruitment for T. communis in 2013/2014, suggesting that changes in the recruitment success of one species can affect the structure of an entire community.

Changes in benthic communities of Port Phillip Bay, Australia, between 1969 and 1995

1998 ◽  
Vol 49 (8) ◽  
pp. 847 ◽  
Author(s):  
Robin S. Wilson ◽  
Simon Heislers ◽  
Gary C. B. Poore
Keyword(s):  
Benthic Communities ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Suspension Feeding ◽  
Deposit Feeders ◽  
Low Levels ◽  
Muddy Sediments ◽  
Sandy Sediments ◽  
Major Division

Changes in benthic communities in Port Phillip Bay, Australia, were assessed over a 25- year period by comparing an intense bay-wide survey carried out in the early 1970s, a 3-year study in the mid 1970s, a limited survey in the early 1990s, and a resurvey in the mid 1990s. A major division of benthic communities into those on deeper muddy sediments and those on marginal sandy sediments persisted was less well defined (by ordination methods) in the 1990s than in the 1970s. The densities of individuals and species declined significantly, but absolute numbers of taxa did not change noticeably. Nevertheless, temporal variability in all variables over 25 years was within the range reported for the 3- year study. Polychaetes have become relatively more abundant than crustaceans and molluscs, and the proportion of suspension-feeding organisms has increased at the expense of deposit feeders. The introduced Japanese bivalve Theora lubrica was the most abundant invertebrate in the 1970s. In the 1990s, this species, the European bivalve Corbula gibba and the polychaete Euchone limnicola were the most abundant. Decreasing abundances of macrobenthic invertebrates, and a decreasing proportion of deposit feeders, is consistent with a decrease in nutrient load from moderate to low levels—such as occurred with reduced discharge from Melbourne’s sewage treatment plant—but lack of contemporaneous data prevents further explanation.

scholarly journals A new method for voice signal features creation

2019 ◽  
Vol 9 (5) ◽  
pp. 4092
Author(s):  
Majed O. Al-Dwairi ◽  
Amjad Y. Hendi ◽  
Mohamed S. Soliman ◽  
Ziad A. A. AlQadi
Keyword(s):  
Acoustic Signal ◽  
New Method ◽  
Digital Audio ◽  
Human Knowledge ◽  
Voice Signal ◽  
Large Size ◽  
Signal Features

Digital audio is one of the most important types of data at present. It is used in several applications, such as human knowledge and many security and banking applications. A digital voice signal is usually of a large size where the acoustic signal consists of a set of values distributed in one column (one channel) (mono signal) or distributed in two columns (two channels) (stereo signal), these values usually are the results of sampling and quantization of the original analogue voice signal. In this paper we will introduce a method which can be used to create a signature or key, which can be used later to identify or recognize the wave file. The proposed method will be implemented and tested to show the accuracy and flexibility of this method.

scholarly journals Relations of physical and biogenic reworking of sandy sediments in the southeastern North Sea

2019 ◽  
Author(s):  
Knut Krämer ◽  
Soeren Ahmerkamp ◽  
Ulrike Schückel ◽  
Moritz Holtappels ◽  
Christian Winter
Keyword(s):  
North Sea ◽  
Benthic Communities ◽  
Benthic Fauna ◽  
Small Scale ◽  
Bottom Water Temperature ◽  
Sediment Reworking ◽  
Physical Forcing ◽  
Shelf Seas ◽  
Seafloor Sediments ◽  
Sandy Sediments

Abstract. The reworking of sandy sediments in shallow coastal and shelf seas is mainly driven by physical forcing in the form of wave- and current-induced shear stress. As an important habitat for benthic species seeking shelter and food, the upper seafloor is also marked by intense bioturbation. Although this reworking activity is recognized as an important mechanism for the exchange of particular matter and solutes between sediment and water column, quantifications and assessments of the relative importance of physical and biogenic reworking of subtidal shelf sediments are rare. This work presents in situ measurements of volumetric reworking rates from six different locations in the southeastern North Sea. The investigated sites cover a range of water depths between 23 and 41 m, different magnitudes of physical (wave and current) forcing and sedimentological conditions as well as different habitats and benthic communities. The measured biogenic reworking rates reach up to 14 % of physically driven reworking via bedform migration. Comparisons with physical quantities water depth, median grain size, bottom water temperature and flow velocity reveal good correlations and allow for an approximation of the biogenic reworking rate from a combination of these readily available oceanographic parameters. The diffusive relocation of sediment by benthic fauna also influences the topography of small scale bedforms and may reduce their height by up to 10 % in a few hours during hydrodynamically inactive conditions. The observations show that even in an energetic environment such as the southeastern North Sea, the benthic fauna contributes an important regulating ecosystem service by overturning upper seafloor sediments. This reworking mechanism becomes particularly important in areas and during periods of sub-threshold conditions for physically driven sediment reworking.

Changes in biological traits of macro-benthic communities subjected to different intensities of demersal trawling along the west coast of southern Africa

2013 ◽  
Vol 93 (8) ◽  
pp. 2027-2038 ◽  
Author(s):  
A. Fleddum ◽  
L.J. Atkinson ◽  
J.G. Field ◽  
P. Shin
Keyword(s):  
Southern Africa ◽  
West Coast ◽  
Benthic Communities ◽  
Biological Traits ◽  
Benthic Assemblages ◽  
The West ◽  
Faunal Assemblages ◽  
Sampling Locations ◽  
General Potential ◽  
Ecological Functioning

Biological traits analysis (BTA) is considered to be a powerful technique for describing the ecological functioning of marine benthic assemblages. This study is the first to apply BTA to assess differences in the traits of benthic faunal assemblages between areas exposed to heavy and light trawling in a major upwelling ecosystem along the west coast of southern Africa. The data were collected from two sampling locations in Namibia and six sampling locations in South Africa. The intensity of trawling varied from area to area. Significant differences in biological traits (BT) were detected between heavily and lightly trawled areas. Weighted infaunal traits showed significant differences between heavily and lightly trawled areas for 17% of the traits investigated, while 24% of epifaunal traits investigated were significantly different between areas of different trawling intensities. This suggests that the measured BTs of the epifauna might be more sensitive to trawling disturbances than BTs of the infauna. The infaunal traits differed significantly between areas with larger or smaller proportions of sand and mud. Nevertheless, more of the significant differences in infaunal BTs were related to variations in trawling intensity than to variations in sediment composition. Significant modifications of BTs are likely to lead to modified functioning of the community and provide more general potential indicators for management than those based on species. The study confirms the need for more basic biological and life history data on macro-benthic invertebrates but nevertheless shows that BTA detected specific features that correlate with trawling intensity and that these features may be important for epifaunal assemblage functioning.

Mapping seabed biotopes at Hastings Shingle Bank, eastern English Channel. Part 1. Assessment using sidescan sonar

2004 ◽  
Vol 84 (3) ◽  
pp. 481-488 ◽  
Author(s):  
Craig J. Brown ◽  
Alison J. Hewer ◽  
William J. Meadows ◽  
David S. Limpenny ◽  
Keith M. Cooper ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Benthic Communities ◽  
Video Camera ◽  
Sidescan Sonar ◽  
English Channel ◽  
Survey Area ◽  
Benthic Assemblages ◽  
Additional Information ◽  
The North ◽  
Sediment Types

A multi-technique approach was used to map the spatial distribution of seabed biotopes (i.e. physical habitats and their associated benthic assemblages) in the vicinity of Hastings Shingle Bank in the eastern English Channel, part of which is licensed for the extraction of marine aggregates for the construction industry. An area of seabed, approximately 12×4 km in size, was surveyed using a high-resolution sidescan sonar system, and a mosaic of the output was produced, covering 100% of the survey area. The area was then divided into acoustically distinct regions based on the sidescan sonar data, and the benthic communities and sediment types within each of the regions were ground-truthed using a Hamon grab fitted with a video camera, and using a heavy duty 2-m beam trawl. Additional information concerning the seabed was obtained through the application of video and photographic techniques. Sediments within the survey area ranged from cobbles and coarse gravels on the Shingle Bank, to various grades of sands to the north and south. Analysis of faunal data revealed the presence of statistically distinct biological assemblages within each acoustic region. Using all available data, four discrete biotopes were identified and their spatial distribution mapped across the survey area.

The origin of muddy sand sediments associated with mud volcanism in the Horonobe area of northern Hokkaido, Japan

2013 ◽  
Vol 14 (12) ◽  
pp. 4980-4988 ◽  
Author(s):  
Kazuya Miyakawa ◽  
Tetsuya Tokiwa ◽  
Hiroaki Murakami
Keyword(s):  
Muddy Sand ◽  
Mud Volcanism ◽  
Sand Sediments
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