Macro- and megaplanktonic cnidarians collected in the eastern part of the Weddell Gyre during summer 1979

1994 ◽  
Vol 74 (4) ◽  
pp. 873-894 ◽  
Author(s):  
F. Pagès ◽  
P.R. Pugh ◽  
J.-M. Gili
Keyword(s):  
Spatial Distribution ◽  
Species Composition ◽  
Water Column ◽  
Depth Range ◽  
Sampling Area ◽  
Weddell Gyre ◽  
Depth Ranges ◽  
Species Being ◽  
Very High ◽  
High Diversity

The species composition, abundance and spatial distribution of macroplanktonic cnidarians in the eastern part of the Weddell Gyre are described from a series of nekton samples collected over three depth ranges between 0 and 2000 m. On average, cnidarians contributed 52·6% to the biovolume of these samples, although the range was high (5·0–93·1%). In total 23 species of siphonophores and 20 species of medusae were identified; a number that is very high in comparison with previous studies. There was a high diversity at bathypelagic depths, with 38 species being collected below 1000 m. The most abundant siphonophores were Dimophyes arctica (up to 45 nectophores per 104 m3) and Heteropyramis crystallina (up to 22 nectophores per 104 m3). The most abundant medusa was Pantachogon haeckeli (up to 30 specimens per 104 m3). Medusae were most abundant at mesopelagic depths, reaching 46 specimens per 104 m3 in the 500–1000 m depth range. Smaller calycophoran siphonophores were concentrated in the top 500 m of the water column, with total numbers averaging 107 per 104 m3. The number of larger calycophorans in-creased with depth, being most abundant in the 1000–2000 m depth range. Although many species had a widespread geographical distribution within the sampling area, the hydrographical conditions appeared to be affecting the distribution of some.

Grenadiers of the World Oceans: Biology, Stock Assessment, and Fisheries

2008 ◽  
Keyword(s):  
Stock Assessment ◽  
Distribution Data ◽  
Depth Range ◽  
Multivariate Statistical ◽  
Data Set ◽  
Species Checklist ◽  
The World ◽  
Depth Ranges ◽  
The Vertical Distribution ◽  
Very High

<em>Abstract.</em>—Extensive trawling efforts off Taiwan, supplemented by collections from trawlers’ harvest at several local fishing harbors, have raised the total number of Taiwan’s grenadier fishes to 71 species in 18 genera and 3 families. Despite a relatively limited coastline (500 nautical miles), the species diversity in Taiwan is very high. The largest genus <em>Coelorinchus </em>(formerly known as <em>Caelorinchus</em>) is represented by 21 species, followed by <em>Ventrifossa </em>with 8, and <em>Nezumia </em>with 6. All other genera had five or fewer representatives. Five species were described based on specimens from Taiwan, and two of them, <em>Coelorinchus leptorhinus </em>and <em>C. sheni, </em>have not been reported elsewhere. A total of 33 species and 10 genera are newly recorded from Taiwan; these were collected only within the past two years. Because the maximum depth trawled only reached about 2,000 m in this study, it should be expected that more deeper-water grenadiers will be found in the future. Our depth-distribution data-set of collected specimens and depth ranges from 55 stations were insufficient to effectively separate the species into groups using multivariate statistical analysis. However, the factors influencing grenadier species composition in this study still can be recognized as per the following sequence: water depth, geographical region, and type of net. The vertical distribution of grenadiers in Taiwan appears to have a separation at 600 m and 1000 m. An annotated species checklist with ASIZP cataloged specimens documenting Taiwan distributions, and detailed collecting information, including body size, location, and depth range are provided.

scholarly journals The demersal fish assemblages of the infra and circalittoral coastal rocky bottoms of the Aeolian Archipelago (Central Mediterranean Sea) studied by Remotely Operated Vehicle (ROV)

2020 ◽  
Author(s):  
IVAN CONSALVO ◽  
GABRIELE La MESA ◽  
SIMONEPIETRO CANESE ◽  
MICHELA GIUSTI ◽  
EVA SALVATI ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Fish Assemblages ◽  
Demersal Fish ◽  
Total Density ◽  
Depth Range ◽  
Remotely Operated Vehicle ◽  
Depth Ranges ◽  
Aeolian Archipelago ◽  
Rocky Bottoms

Demersal fish assemblages on the rocky bottoms of the Aeolian Archipelago were investigated using a Remotely Operated Vehicle (ROV) within the framework of research activities aimed at drawing up the zoning proposal of a new Italian national marine protected area. Visual assessments were conducted around the seven main islands by means of a total of 36 ROV transects. Video material was divided into 3 parts belonging to 3 Archipelago sectors (Western, Central and Eastern) and into 3 depth ranges (20-50, 51-120, 121-190). Thirty taxa of teleosts (29 species and 1 genus) belonging to 16 families were recorded. The assemblages were numerically dominated by some schooling fishes, such as Anthias anthias, Callanthias ruber and Chromis chromis, which exhibited a depth related partitioning of space, and three non-gregarious species, i.e. Serranus cabrilla, Coris julis and Lappanella fasciata. In terms of species composition, the assemblages observed in the sectors of the Archipelago largely overlapped. No significant sector-related differences were detected in fish species richness, diversity and total density. Species composition and the investigated assemblage parameters were significantly affected by depth. The pattern of variation in species richness among depth ranges changed depending on the archipelago sectors. No significant interaction between the factors depth range and sector was observed for species diversity and total density. Diversity values at 20-50 and 121-190 m depth were similar and significantly higher than that at 51-120 m depth. Fish total density showed a clear decreasing trend with increasing depth, though significant differences were detected between the 20-50 and 51-120 depth layers and the deepest one. Overall, the demersal fish assemblage of the Aeolian Archipelago was poorly diversified and depleted, most likely due to overfishing. This information highlighted the importance of the adoption of specific measures aimed at the recovery of overexploited resources and the restoration of the whole marine ecosystems.

Spatial distribution of rotifers (Rotifera) in monospecies beds of invasive Vallisneria spiralis L. in heated lakes

2011 ◽  
Vol 40 (4) ◽  
Author(s):  
Jolanta Ejsmont-Karabin ◽  
Andrzej Hutorowicz
Keyword(s):  
Spatial Distribution ◽  
Species Composition ◽  
Large Scale ◽  
Cooling System ◽  
Species Abundance ◽  
Small Scale ◽  
Power Stations ◽  
Sampling Points ◽  
High Diversity ◽  
Rotifer Communities

AbstractSpecies abundance and richness of rotifer communities occupying monospecies beds of Vallisneria was studied in Lake Licheńskie included in the open cooling system of heat and power stations. Differences were found in rotifer numbers, species composition and diversity between sampling points within the same location and between the locations. Factors that seem to be responsible for the high diversity of rotifer communities inhabiting Vallisneria beds are: large-scale horizontal diversity (between macrophyte patches), small-scale horizontal diversity (within patches) and the high vulnerability of Vallisneria epiphyton to disturbances caused by wave action.

Modern and Holocene microbial mats and associated microbially induced sedimentary structures (MISS) on the southeastern coast of Tunisia (Mediterranean Sea)

2020 ◽  
pp. 1-21
Author(s):  
Rached Lakhdar ◽  
Mohamed Soussi ◽  
Rachida Talbi
Keyword(s):  
Spatial Distribution ◽  
High Frequency ◽  
Depositional Environment ◽  
Microbial Mats ◽  
Coastal Environment ◽  
Tidal Dynamics ◽  
Very High Frequency ◽  
Intertidal Zones ◽  
Sedimentary Structures ◽  
Very High

Abstract On the southeastern Tunisian coastline, very diverse living microbial mats colonize the lower supratidal and intertidal zones, and locally may extend into the upper infratidal zone. The interaction between the benthic cyanobacteria and their siliciclastic substratum leads to the development of several types of microbially induced sedimentary structures (MISS). The mapping of the microbial mats has allowed the identification of the types of MISS that characterize the different segments of the coastal environment. The modern microbial mats have been compared with those recorded at the top of the Holocene deposits, which are composed of biodegraded microbial black mats alternating with white laminae made of clastic and evaporitic sediments, indicative of very high frequency cycles of flood and drought. A hypothetic profile showing their occurrences along the different areas bordering the coastline is proposed as a guide for the reconstruction of the ancient depositional environment. The roles of tidal dynamics, storms, and climate in controlling their genesis and spatial distribution, are discussed and highlighted. The modern MISS of southeastern Tunisia are compared with their equivalents that are well documented through the different geological eras.

scholarly journals Effect of solar ultraviolet radiation (280–400 nm) on the eggs and larvae of Atlantic cod (Gadus morhua)

1999 ◽  
Vol 56 (6) ◽  
pp. 1058-1067 ◽  
Author(s):  
France Béland ◽  
Howard I Browman ◽  
Carolina Alonso Rodriguez ◽  
Jean-François St-Pierre
Keyword(s):  
Water Column ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Outdoor Exposure ◽  
Ultraviolet B ◽  
Solar Ultraviolet Radiation ◽  
Mortality Effect ◽  
Eggs And Larvae ◽  
Very High ◽  
Solar Ultraviolet

In the Gulf of St. Lawrence, Canada, solar ultraviolet B radiation (UV-B, 280-320 nm) penetrates a significant percentage of the summer mixed-layer water column: organisms residing in this layer, such as the eggs of Atlantic cod (Gadus morhua), are exposed to UV-B. In outdoor exposure experiments, Atlantic cod eggs were incubated in the presence versus the absence of UV-B and (or) UV-A (320-400 nm). We tested two hypotheses: H1, UV-B induces mortality in Atlantic cod eggs, and H2, UV-A either exacerbates or mitigates any such UV-B-induced mortality. Hypothesis H1 was supported: there was a significant mortality effect on Atlantic cod eggs exposed to UV-B at the surface and at a depth of 50 cm. Hypothesis H2 was not supported: there was no effect of UV-A. These experiments indicate that Atlantic cod eggs present in the first metre of the water column (likely only a small percentage of the total egg population) are susceptible to UV-B. However, UV-B must be viewed as only one among many environmental factors that produce the very high levels of mortality typically observed in the planktonic early life stages of marine fishes.

scholarly journals Spatial distribution and species composition of small pelagic fishes in the Gulf of California

2006 ◽  
Author(s):  
Edgar Lanz ◽  
Manuel O. Nevárez Martínez ◽  
Juana López Martínez ◽  
Juan A. Dworak
Keyword(s):  
Spatial Distribution ◽  
Species Composition ◽  
Gulf Of California ◽  
Pelagic Fishes

scholarly journals Radiocesium in the Taiwan Strait and the Kuroshio east of Taiwan from 2018 to 2019

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei-Jen Huang ◽  
Ming-Ta Lee ◽  
Kuei-Chen Huang ◽  
Kai-Jung Kao ◽  
Ming-An Lee ◽  
...  
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Half Life ◽  
North Pacific Ocean ◽  
Taiwan Strait ◽  
Depth Range ◽  
Near Surface ◽  
Activity Concentrations ◽  
The Taiwan Strait ◽  
The Kuroshio

AbstractThe release of anthropogenic radiocesium to the North Pacific Ocean (NPO) has occurred in the past 60 years. Factors controlling 137Cs (half-life, 30.2 year) and 134Cs (half-life, 2.06 year) activity concentrations in the Kuroshio east of Taiwan and the Taiwan Strait (latitude 20° N–27° N, longitude 116° E–123° E) remain unclear. This study collected seawater samples throughout this region and analyzed 134Cs and 137Cs activity concentrations between 2018 and 2019. A principal component analysis (PCA) was performed to analyze the controlling factors of radiocesium. Results of all 134Cs activity concentrations were below the detection limit (0.5 Bq m−3). Analyses of water column 137Cs profiles revealed a primary concentration peak (2.1–2.2 Bq m−3) at a depth range of 200–400 m (potential density σθ: 25.3 to 26.1 kg m−3). The PCA result suggests that this primary peak was related to density layers in the water column. A secondary 137Cs peak (1.90 Bq m−3) was observed in the near-surface waters (σθ = 18.8 to 21.4 kg m−3) and was possibly related to upwelling and river-to-sea mixing on the shelf. In the Taiwan Strait, 137Cs activity concentrations in the near-surface waters were higher in the summer than in the winter. We suggest that upwelling facilitates the vertical transport of 137Cs at the shelf break of the western NPO.

scholarly journals ANALISIS KOMUNITAS MANGROVE DI KECAMATAN SEKOTONG LOMBOK BARAT NTB

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Lalu Japa ◽  
Didik Santoso
Keyword(s):  
Cluster Analysis ◽  
Species Composition ◽  
Key Words ◽  
Tree Density ◽  
Mangrove Tree ◽  
Rhizophora Apiculata ◽  
Percentage Similarity ◽  
Percentage Covering ◽  
Very High ◽  
Program Version

Abstrak:Komunitas mangrove di kawasan Sekotong Lombok Barat telah diteliti untuk mengetahui komposisi spesies, kerapatan  individu setiap spesies,dan  persentase tutupannya. Total sebanyak 28 plot (kudrat) berukuran 10m x 10m dibuat pada 9 transek di lima stasiun. Foto tutupan kanopi mangrove dan parameter komposisi komunitas dianalisis menggunakan software ImageJ dan template spreadsheet. Data kerapatan pohon dan persentase tutupan mangrove dianalisis dengan ANOVA. Persentase kesamaan antara stasiun menggunakan Biodiversity Program Version 2 berdasarkan the Bray Curtis Cluster Analysis. Komunitas mangrove di Kecamatan Sekotong Lombok Barat teridenfikasi 8 spesies, meliputi 5 genus, dan 4 famili. Rhizophora apiculata tersebar disemua transek penelitian. Transek SKTM02B memiliki kerapatan pohon tertinggi sebesar 2800 pohon/ha. Tiga transek dengan persentase tutupan tertinggi berturut-turut SKTM04T, SKTM04, dan SKTM01A. Persentase kesamaan antar stasiun sangat tinggi mencapai 82,503 –  95,423%. Persentase kesamaan tertinggi (95,423%) terjadi antara stasium SKTM04 dan SKTM05. Kata kunci : mangrove, Sekotong, komposisi spesies, kerapatan, dan persentase tutupan Abstract: Community of mangrove in the area of Sekotong West Lombok has been researched to know the species composition,  individual density of each species, and percentage covering. Total number of 28 plots of 10 m x 10 m in size were set in 9 transects in 5 station. Photographs mangrove canopy covering and parameter of mangrove community composition were analyzed by using the software ImageJ and  template spreadsheet. ANOVA was applied for analyzing the data of mangrove  tree density and percentage covering. The Bray Curtis Cluster Analysis. using Biodiversity Program Version 2 was also used for analyzing the percentage similarity among station. The community of mangrove of Sekotong West Lombok consists of 8 species, 5 genera, dan 4 family. Rhizophora apiculata was recorded in all transects. The highest density (2800 trees/ha) of mangrove was recorde in ransect SKTM02B.. The three transects with the highest percentage covering were SKTM04T, SKTM04, dan SKTM01A, respectively. Percentages similarity among station were very high (82,503%  –  95,423%). SKTM04 and SKTM05 were the two station with  the highest percentage similarity (95,423%). Key words : mangrove, Sekotong, species composition, density, and percentage covering 

scholarly journals Evaluation of the corridor method for oak (Quercus sp.) cultivation using research objects in the Mircze and Kościan Forest Districts as an example

2018 ◽  
Vol 79 (1) ◽  
pp. 29-35
Author(s):  
Rafał Paluch ◽  
Wojciech Gil
Keyword(s):  
Species Composition ◽  
Quality Index ◽  
Oak Regeneration ◽  
Age Classes ◽  
Good Production ◽  
Corridor Method ◽  
Research Objects ◽  
Predicted Values ◽  
19Th And 20Th Century ◽  
Very High

Abstract The corridor method of oak (Quercus sp) cultivation is an old, forgotten silvicultural method. It was developed around the turn of the 19th and 20th century on the south-eastern borders of Poland (Podole, Wołyń) and Russia and made use of other species such as hornbeam, linden and birch as a cover for oak, which is a tree species sensitive to frosts. The nowadays recurring phenomenon of oak disease initiated a search for silvicultural alternatives and thus the usefulness of reviving the corridor method for oak regeneration was investigated by examining existing tree stands established in this way. Our research plots were located in five young stands and two in mature as well as old stands. In the stands of the 2nd and 3rd age classes, the density of oaks was observed to be 1500–3500/ha, which accounted for 30–50%. The density of oak in old stands (7th age class) was similar to model-predicted values. Furthermore, the corridor method gave very good production results as exemplified by the oak stands growing on the fresh broadleaved site, which had a very high stand quality index. In addition, the species composition was observed to diversify throughout these oak stands’ development, thus supporting arguments for the conservation and preservation of oak-hornbeam forests. To summarise, the prerequisites for the success of the corridor method are systematic cuts of young stands (forest cultures and thickets) to inhibit the growth of accompanying undesired species and limiting the number of grazing animals.

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