Demersal fish and cephalopod communities of an unexploited coastal environment in northern Australia

1982 ◽  
Vol 33 (6) ◽  
pp. 1039 ◽  
Author(s):  
SF Rainer ◽  
ISR Munro
Keyword(s):  
Distribution Patterns ◽  
Demersal Fish ◽  
Common Species ◽  
Tropical Fish ◽  
Distribution Data ◽  
Sediment Type ◽  
Physical Factors ◽  
Trawl Fishery ◽  
Bottom Depth ◽  
Trawl Fisheries

Fish communities in the south-eastern Gulf of Carpentaria were surveyed before the development of a demersal trawl fishery for prawns. Distribution data for fish and cephalopods were examined to determine community composition and species-distribution patterns in an unexploited shallow-water tropical fish community. Common species were mostly Indo-west Pacific in affinity, and included many species important in demersal trawl fisheries. Three clusters of site groups were present, comprising site groups from nearshore (~2-5 m), shallow offshore, and deep offshore (~15-35 m) areas, respectively. Site groups did not correspond to clearly defined communities. Species overlaps were frequent. Limits to the distribution of common species seemed to be related more to physical factors (bottom depth, salinity and sediment type) than to other biotic factors (distribution of species). The overall picture was of a rich assemblage of fish species in an environment characterized by gradients rather than by sharp changes.

Distribution, biomass and community structure of demersal fishes of the Gulf of Carpentaria, Australia

1994 ◽  
Vol 45 (3) ◽  
pp. 375 ◽  
Author(s):  
SJM Blaber ◽  
DT Brewer ◽  
AN Harris
Keyword(s):  
Community Structure ◽  
Abiotic Factors ◽  
Fish Fauna ◽  
Distribution Patterns ◽  
Demersal Fish ◽  
Fish Distribution ◽  
Sediment Type ◽  
Principal Coordinates Analysis ◽  
Main Site ◽  
Principal Coordinates

The demersal fish fauna of the Gulf of Carpentaria was surveyed during November and December 1990. Over 300 species from 85 families were caught by trawling a systematic grid of 107 stations. The absolute mean biomass was 124.8 kg ha-1 (s.e. =44.1) for day trawls and 53.7 kg ha-1 (s.e. =6.0) for night trawls. The overall mean catch rates were 421.3 kg h-1 (s.e. = 128.5) for day trawls and 198.6 kg h-1 (s.e. =21.5) for night trawls. Biomasses were twice as high in the prawn-trawling grounds of Albatross Bay, the south-eastern gulf and Groote Eylandt as they were elsewhere in the gulf. Twenty-five species made up 75% of the biomass; the dominant families were Haemulidae, Carangidae, Leiognathidae and Nemipteridae. Community-structure and distribution patterns were analysed by numerical classification techniques and principal-coordinates analysis. These indicated six main site groups and 15 fish community groups, based on fish species occurrences and biomasses. There was a relationship between fish distribution patterns and depth of water but not other abiotic factors recorded (sediment type, salinity, temperature and turbidity).

Drivers of diversity gradients of a highly mobile marine assemblage in a mesoscale seascape

2020 ◽  
Vol 638 ◽  
pp. 149-164
Author(s):  
GM Svendsen ◽  
M Ocampo Reinaldo ◽  
MA Romero ◽  
G Williams ◽  
A Magurran ◽  
...  
Keyword(s):  
Environmental Gradients ◽  
Regression Tree ◽  
Demersal Fish ◽  
Open Ocean ◽  
Shared Resources ◽  
Thermal Front ◽  
Boosted Regression Tree ◽  
Diversity Gradients ◽  
Α Diversity ◽  
Bottom Depth

With the unprecedented rate of biodiversity change in the world today, understanding how diversity gradients are maintained at mesoscales is a key challenge. Drawing on information provided by 3 comprehensive fishery surveys (conducted in different years but in the same season and with the same sampling design), we used boosted regression tree (BRT) models in order to relate spatial patterns of α-diversity in a demersal fish assemblage to environmental variables in the San Matias Gulf (Patagonia, Argentina). We found that, over a 4 yr period, persistent diversity gradients of species richness and probability of an interspecific encounter (PIE) were shaped by 3 main environmental gradients: bottom depth, connectivity with the open ocean, and proximity to a thermal front. The 2 main patterns we observed were: a monotonic increase in PIE with proximity to fronts, which had a stronger effect at greater depths; and an increase in PIE when closer to the open ocean (a ‘bay effect’ pattern). The originality of this work resides on the identification of high-resolution gradients in local, demersal assemblages driven by static and dynamic environmental gradients in a mesoscale seascape. The maintenance of environmental gradients, specifically those associated with shared resources and connectivity with an open system, may be key to understanding community stability.

Distribution of moss-inhabiting diatoms along an altitudinal gradient at sub-Antarctic Îles Kerguelen

2007 ◽  
Vol 19 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Niek J.M. Gremmen ◽  
Bart van de Vijver ◽  
Yves Frenot ◽  
Marc Lebouvier
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Altitudinal Gradient ◽  
Cross Validation ◽  
Strong Relationship ◽  
Distribution Patterns ◽  
Common Species ◽  
Important Variable ◽  
Diatom Species ◽  
Expected Species Richness

Altitudinal gradients provide excellent opportunities to study relationships between species distribution and climatic variables. We studied the species composition of 39 samples of moss-inhabiting diatoms, collected at 50 m intervals from 100–650 m above sea level. The samples contained a total of 130 diatom species, of which 51 occurred in 10 or more samples. Altitude appeared to be the most important variable explaining variation in species composition. Of the 51 common species, 33 showed a significant relationship with altitude. Although the majority of the latter declined with increasing altitude, for nine species the probability of occurrence first increased with increasing elevation, but decreased again at higher altitudes, and four species increased systematically with elevation. As a result, expected species richness per sample decreased from an estimated 43 at 100 m to 25 species per sample at 650 m. Diatom distribution patterns proved to be suitable predictors of the altitudinal position of sample sites. Cross-validation yielded a strong relationship between predicted and observed altitudes.

scholarly journals Preventive maintenance pada mesin die casting dengan age replacement model untuk peningkatan reliabilitas mesin

2020 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Andriani Andriani ◽  
Ikhsan Romli
Keyword(s):  
Preventive Maintenance ◽  
Die Casting ◽  
Casting Machine ◽  
Engine Performance ◽  
Cost Savings ◽  
Distribution Patterns ◽  
Distribution Data ◽  
Time Data ◽  
Replacement Model ◽  
Age Replacement

In an industry, the maintenance department plays a very important role in ensuring the smooth production process. The method of machine maintenance with preventive maintenance is a strategy that can be used to repair existing machines. This is related to proper and regular maintenance can improve engine performance and reduce the level of engine damage which will increase the continuity of production activities. In the die casting division of PT Astra Honda Motor in the observation on the die casting machine 07 there were 45 times damage to the ladle component and 11 times the damage to the auto spray component. These two components are critical components of the 07 die casting machine. After testing the compatibility index and the good compatibility of the damage time data and repair time data to obtain distribution data distribution patterns, obtain the tablespoon component MTTF assessment results of 107,833 hours and auto spray components amounting to 314,226 hours. Whereas the MTTR value of the spoon component is 0.385 hours and the auto spray component is 0.766 hours. The next step is to look for critical component replacement time intervals with the age replacement model, to further review whether it is related to increased reliability, decrease in total downtime, and cost savings before preventive maintenance is carried out and after preventive maintenance is carried out.

scholarly journals Distribution patterns and conservation status of Crocus species in Iran, one of the diversity centers of Crocus in the Middle East

2021 ◽  
Vol 48 (2) ◽  
pp. 156-168
Author(s):  
Melika Tabasi ◽  
Ahmadreza Mehrabian ◽  
Sadaf Sayadi
Keyword(s):  
Middle East ◽  
Conservation Status ◽  
Distribution Patterns ◽  
Field Studies ◽  
Distribution Data ◽  
Herbarium Specimens ◽  
Distribution Centers ◽  
Boundary Area ◽  
Universal Transverse Mercator ◽  
Western Asia

Abstract Assessing distribution patterns of valuable taxa plays an important role in the biodiversity conservation of these taxa. The genus Crocus L. (Iridaceae) comprises about 100 species that are distributed mainly in the Mediterranean region and western Asia. The present study purposed to assess the distribution patterns of Iranian Crocus species (including C. sativus L. and 8 wild species) and their conservation status in Iran as one of diversity centers of Crocus in the Middle East. A set of geographic distribution data was compiled through field studies, and reviews of herbarium specimens, iNaturalist, and various Flora. Localities were marked on geo-referenced maps (1/106) of Iran using ArcView version 3.2 (Esri, 2000). The distribution patterns of the taxa were mapped per 0.25° × 0.25° universal transverse Mercator grid cells (25 km2 with the exception of boundary area). Based on the species distribution (SDI) (33%) and species specialization (SSI) (44%) indices, those Iranian Crocus species that are threatened are mainly distributed in Irano-Turanian region. The mountainous ecosystems of Almeh and Western Alborz are important distribution centers of these taxa. Iranian Crocus species with SSI < 0.5 (C. almehensis, C. gilanicus, C. michelsonii, and C. caspius) have the highest conservation value.

scholarly journals In situ observations show vertical community structure of pelagic fauna in the eastern tropical North Atlantic off Cape Verde

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
H. J. T. Hoving ◽  
P. Neitzel ◽  
H. Hauss ◽  
S. Christiansen ◽  
R. Kiko ◽  
...  
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Global Climate ◽  
Distribution Patterns ◽  
Cape Verde ◽  
Distribution Data ◽  
Low Oxygen ◽  
Study Region ◽  
Tropical North Atlantic ◽  
Minimum Zone

AbstractDistribution patterns of fragile gelatinous fauna in the open ocean remain scarcely documented. Using epi-and mesopelagic video transects in the eastern tropical North Atlantic, which features a mild but intensifying midwater oxygen minimum zone (OMZ), we established one of the first regional observations of diversity and abundance of large gelatinous zooplankton. We quantified the day and night vertical distribution of 46 taxa in relation to environmental conditions. While distribution may be driven by multiple factors, abundance peaks of individual taxa were observed in the OMZ core, both above and below the OMZ, only above, or only below the OMZ whereas some taxa did not have an obvious distribution pattern. In the eastern eropical North Atlantic, OMZ expansion in the course of global climate change may detrimentally impact taxa that avoid low oxygen concentrations (Beroe, doliolids), but favour taxa that occur in the OMZ (Lilyopsis, phaeodarians, Cydippida, Colobonema, Haliscera conica and Halitrephes) as their habitat volume might increase. While future efforts need to focus on physiology and taxonomy of pelagic fauna in the study region, our study presents biodiversity and distribution data for the regional epi- and mesopelagic zones of Cape Verde providing a regional baseline to monitor how climate change may impact the largest habitat on the planet, the deep pelagic realm.

Habitat filtering of six coexisting Heliconia species in a lowland tropical rain forest in Amazonian Ecuador

2019 ◽  
Vol 35 (2) ◽  
pp. 91-94 ◽  
Author(s):  
Elizabeth L. Tokarz ◽  
Pablo Álvia ◽  
Renato Valencia ◽  
Simon A. Queenborough
Keyword(s):  
Rain Forest ◽  
National Park ◽  
Distribution Patterns ◽  
Common Species ◽  
Habitat Filtering ◽  
Yasuni National Park ◽  
Amazonian Ecuador ◽  
Amazonian Rain Forest ◽  
Random Manner ◽  
Occurrence Pattern

AbstractHerbaceous plants are often under-studied in tropical forests, despite their high density and diversity, and little is known about the factors that influence their distribution at microscales. In a 25-ha plot in lowland Amazonian rain forest in Yasuní National Park, Ecuador, we censused six species of Heliconia (Heliconiaceae) in a stratified random manner across three topographic habitat types. We observed distribution patterns consistent with habitat filtering. Overall, more individuals occurred in the valley (N = 979) and slope (N = 847) compared with the ridge (N = 571) habitat. At the species level, Heliconia stricta (N = 1135), H. spathocircinata (N = 309) and H. ortotricha (N = 36) all had higher abundance in the valley and slope than ridge. Further, H. vellerigera (N = 20) was completely absent from the ridge. Conversely, H. velutina (N = 903) was most common in the drier ridge habitat. The two most common species (H. stricta and H. velutina) had a reciprocal or negative co-occurrence pattern and occurred preferentially in valley versus ridge habitats. These results suggest that taxa within this family have different adaptations to the wetter valley versus the drier ridge and that habitat partitioning contributes to coexistence.

Relative effects of trap versus trawl fisheries on population dynamics of the northern cod (Gadus morhua) stock

1998 ◽  
Vol 55 (1) ◽  
pp. 76-85 ◽  
Author(s):  
L Fahrig ◽  
S E Pope ◽  
K M Henein ◽  
G A Rose
Keyword(s):  
Population Dynamics ◽  
Gadus Morhua ◽  
Simulation Modelling ◽  
Trawl Fishery ◽  
Trawl Catch ◽  
Stock Biomass ◽  
Northern Cod ◽  
Trap Fishery ◽  
Using Data ◽  
Trawl Fisheries

We compared the effects of the inshore trap and the offshore trawl fisheries on the population dynamics of the northern cod (Gadus morhua) stock using data analyses and simulation modelling. We first statistically characterized the catch versus stock biomass relationships for the two fisheries (1977-1986). We found a significant (P < 0.0001) relationship between the trawl catch at time t and the stock biomass at time t - 2. No temporal lag was evident in the trap catch versus stock biomass relationship. The variability in these two relationships was similar. We then modelled the catch and stock biomass dynamics of the two fisheries in parallel, incorporating the observed catch versus stock biomass relationships, but assuming equal mean catches, to examine the effects on cod population dynamics of the temporal lag and variability in the catch versus stock biomass relationships. The results suggest that, for the same amount of fish taken, a quota-based trawl fishery presents a much greater risk of collapse to the cod stock than does an inshore trap fishery. Current management methods overestimate the "safe" catch for the trawl fishery because they do not incorporate the consequences of the lag in the relationship between stock biomass and trawl catch.

Distribution of Grass Species and Attributes of Grasses Near a Bore Drain in a Grazed Semi-arid Subtropical Grassland

1997 ◽  
Vol 45 (5) ◽  
pp. 919 ◽  
Author(s):  
R. W. Rogers ◽  
C. Stride
Keyword(s):  
Introduced Species ◽  
Carbon Assimilation ◽  
Distribution Patterns ◽  
Common Species ◽  
Grass Species ◽  
Semi Arid ◽  
Selection Of

The distribution of grass species and a selection of attributes of those species were related to distance from water in an otherwise natural, sheep-grazed, semi-arid, subtropical grassland at Glencoban Station near Cunnamulla in south-western Queensland, Australia. Twenty common species could be classified as decreaser, increaser or neutral with respect to stocking pressure based on distribution patterns with respect to distance from water. No species known to be introduced to Australia were present. The occurrence of a diversity of vegetative and diaspore attributes and carbon assimilation pathways were also shown to be related to stocking pressure. The attributes studied showed autocorrelation in two groups, which related to the higher level taxonomy of the grasses and to response to stocking. Chloridoid grasses increase and andropogonoid grasses decrease under high stocking pressure. In this grassland, which has no introduced species, a syndrome of stocking-related attributes can be discerned.

scholarly journals Different bottom trawl fisheries have a differential impact on the status of the North Sea seafloor habitats

2020 ◽  
Vol 77 (5) ◽  
pp. 1772-1786 ◽  
Author(s):  
A D Rijnsdorp ◽  
J G Hiddink ◽  
P D van Denderen ◽  
N T Hintzen ◽  
O R Eigaard ◽  
...  
Keyword(s):  
North Sea ◽  
Management Strategies ◽  
Demersal Fish ◽  
Time Interval ◽  
The North ◽  
The Status ◽  
Fisheries Conservation ◽  
The North Sea ◽  
The Impact ◽  
Trawl Fisheries

Abstract Fisheries using bottom trawls are the most widespread source of anthropogenic physical disturbance to seafloor habitats. To mitigate such disturbances, the development of fisheries-, conservation-, and ecosystem-based management strategies requires the assessment of the impact of bottom trawling on the state of benthic biota. We explore a quantitative and mechanistic framework to assess trawling impact. Pressure and impact indicators that provide a continuous pressure–response curve are estimated at a spatial resolution of 1 × 1 min latitude and longitude (∼2 km2) using three methods: L1 estimates the proportion of the community with a life span exceeding the time interval between trawling events; L2 estimates the decrease in median longevity in response to trawling; and population dynamic (PD) estimates the decrease in biomass in response to trawling and the recovery time. Although impact scores are correlated, PD has the best performance over a broad range of trawling intensities. Using the framework in a trawling impact assessment of ten métiers in the North Sea shows that muddy habitats are impacted the most and coarse habitats are impacted the least. Otter trawling for crustaceans has the highest impact, followed by otter trawling for demersal fish and beam trawling for flatfish and flyshooting. Beam trawling for brown shrimps, otter trawling for industrial fish, and dredging for molluscs have the lowest impact. Trawling is highly aggregated in core fishing grounds where the status of the seafloor is low but the catch per unit of effort (CPUE) per unit of impact is high, in contrast to peripheral grounds, where CPUE per unit of impact is low.

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