Temporal changes in a demersal fish and cephalopod community of an unexploited coastal area in Northern Australia

1984 ◽  
Vol 35 (6) ◽  
pp. 747 ◽  
Author(s):  
SF Rainer
Keyword(s):  
Water Temperature ◽  
Seasonal Changes ◽  
Fish Community ◽  
Demersal Fish ◽  
Temporal Changes ◽  
Tropical Fish ◽  
Trawl Survey ◽  
Depth Range ◽  
Local Abundance ◽  
Different Seasons

A trawl survey of the south-eastern Gulf of Carpentaria carried out at the beginning of a commercial prawn fishery in the 1960s provided data on the demersal fish of an unexploited tropical fish community. The extent of temporal variation in this community was investigated using abundance data on 359 taxa of fish and cephalopods over 13 months in 1963-1964. Seasonal changes in water temperature and salinity were large, particularly in nearshore waters. Catch rates and species richness in nearshore waters were highest during summer, and in offshore waters during autumn or winter. Shannon diversity was variable, with no clear seasonal component. Temporal changes in community composition resulted in large changes between different seasons in the structure of site groups derived by classification; temporal effects within seasons were also found. The numerically dominant species were the leatherjackets Paramonacanthus spp., the ponyfish Equulites leuciscus, the tripodfish Tripodichthys blochii, and the saury Saurida undosquamis. Squid, the ponyfish Leiognathus sp. nr blochi, the butterfly-bream Nemipterus tolu and the grunter Pomadasys maculatus were seasonally abundant. Although species were restricted in their depth range, discrete communities that maintained their identity in different seasons were apparently absent. The relative abundance of many species varied substantially wirh season and probably also over a longer period. Small changes in local abundance were often associated with movement to deeper water at times of high nearshore water temperature (summer) or of reduced nearshore salinity (autumn). Large seasonal changes occurred in the local abundance of estuarine and semidiadromous species. The community shared many species with the demersal fish community of the Gulf of Thailand. It is suggested that similar structural changes in the fish community of the Gulf of Carpentaria may occur in response to intensive fishing. Further research on the effects of demersal fishing and on the interactions of the demersal fish community with commercially important crustaceans is necessary.

Changes in species composition of the demersal fish community in nearshore waters of Kodiak Island, Alaska

2000 ◽  
Vol 57 (6) ◽  
pp. 1169-1180 ◽  
Author(s):  
Franz J Mueter ◽  
Brenda L Norcross
Keyword(s):  
Species Composition ◽  
Major Part ◽  
Fish Community ◽  
Demersal Fish ◽  
Trawl Survey ◽  
Data Set ◽  
Forage Fishes ◽  
Kodiak Island ◽  
Trends Over Time ◽  
Over Time

We examined the species composition of the demersal fish and shrimp community in seven different areas in the nearshore waters of Kodiak Island based on trawl survey data. A major part of the variability in the data set was attributed to trends over time, indicating a significant change in species composition in the early 1980s. Results agree with work by others and show a shift from a community dominated by shrimp and small forage fishes to one dominated by large piscivorous gadid and flatfish species. The shift occurred rather abruptly in most areas between 1980 and 1982, but the pattern of change differed significantly among areas. Correlations between trends in the two groups of species were weak but were consistent with the hypothesis that the decline in shrimp and forage fishes followed, rather than preceded, the increase in large piscivorous fishes. The results suggest predation as a possible mechanism to explain the observed changes.

Dissolved oxygen and temperature best predict deep-sea fish community structure in the Gulf of California with climate change implications

2020 ◽  
Vol 637 ◽  
pp. 159-180
Author(s):  
ND Gallo ◽  
M Beckwith ◽  
CL Wei ◽  
LA Levin ◽  
L Kuhnz ◽  
...  
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Community Composition ◽  
Environmental Conditions ◽  
Deep Sea ◽  
Gulf Of California ◽  
Fish Community ◽  
Demersal Fish ◽  
Fish Community Structure ◽  
Explained Variance

Natural gradient systems can be used to examine the vulnerability of deep-sea communities to climate change. The Gulf of California presents an ideal system for examining relationships between faunal patterns and environmental conditions of deep-sea communities because deep-sea conditions change from warm and oxygen-rich in the north to cold and severely hypoxic in the south. The Monterey Bay Aquarium Research Institute (MBARI) remotely operated vehicle (ROV) ‘Doc Ricketts’ was used to conduct seafloor video transects at depths of ~200-1400 m in the northern, central, and southern Gulf. The community composition, density, and diversity of demersal fish assemblages were compared to environmental conditions. We tested the hypothesis that climate-relevant variables (temperature, oxygen, and primary production) have more explanatory power than static variables (latitude, depth, and benthic substrate) in explaining variation in fish community structure. Temperature best explained variance in density, while oxygen best explained variance in diversity and community composition. Both density and diversity declined with decreasing oxygen, but diversity declined at a higher oxygen threshold (~7 µmol kg-1). Remarkably, high-density fish communities were observed living under suboxic conditions (<5 µmol kg-1). Using an Earth systems global climate model forced under an RCP8.5 scenario, we found that by 2081-2100, the entire Gulf of California seafloor is expected to experience a mean temperature increase of 1.08 ± 1.07°C and modest deoxygenation. The projected changes in temperature and oxygen are expected to be accompanied by reduced diversity and related changes in deep-sea demersal fish communities.

Evaluation of temporal changes of small yellow croaker stock status in East China Sea using trawl survey indices

2018 ◽  
Vol 25 (3) ◽  
pp. 632
Author(s):  
Zunlei LIU ◽  
Cheng CHEN ◽  
Xingwei YUAN ◽  
Linlin YANG ◽  
Liping YAN ◽  
...  
Keyword(s):  
East China Sea ◽  
Temporal Changes ◽  
East China ◽  
Trawl Survey ◽  
Small Yellow Croaker ◽  
China Sea ◽  
Stock Status

scholarly journals Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community

2012 ◽  
Vol 69 (1) ◽  
pp. 8-22 ◽  
Author(s):  
Simon P. R. Greenstreet ◽  
Helen M. Fraser ◽  
Stuart I. Rogers ◽  
Verena M. Trenkel ◽  
Stephen D. Simpson ◽  
...  
Keyword(s):  
North Sea ◽  
Fish Community ◽  
Size Structure ◽  
Demersal Fish ◽  
Community Size ◽  
The North ◽  
Management Objectives ◽  
The North Sea ◽  
Composition Structure ◽  
And Function

Abstract Greenstreet, S. P. R., Fraser, H. M., Rogers, S. I., Trenkel, V. M., Simpson, S. D., and Pinnegar, J. K. 2012. Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community. – ICES Journal of Marine Science, 69: 8–22. Broader ecosystem management objectives for North Sea demersal fish currently focus on restoring community size structure. However, most policy drivers explicitly concentrate on restoring and conserving biodiversity, and it has not yet been established that simply restoring demersal fish size composition will be sufficient to reverse declines in biodiversity and ensure a generally healthy community. If different aspects of community composition, structure, and function vary independently, then to monitor all aspects of community general health will require application of a suite of metrics. This assumes low redundancy among the metrics used in any such suite and implies that addressing biodiversity issues specifically will require explicit management objectives for particular biodiversity metrics. This issue of metric redundancy is addressed, and 15 metrics covering five main attributes of community composition, structure, and function are applied to groundfish survey data. Factor analysis suggested a new interpretation of the metric information and indicated that a minimum suite of seven metrics was necessary to ensure that all changes in the general health of the North Sea demersal fish community were monitored properly. Covariance among size-based and species-diversity metrics was low, implying that restoration of community size structure would not necessarily reverse declines in species diversity.

scholarly journals Natural Productivity, Morphometrics and Seasonal Distribution of Caulerva Racemosa

2021 ◽  
Vol 324 ◽  
pp. 03010
Author(s):  
Tengku Said Raza’i ◽  
Viktor Amrifo ◽  
Imam Pangestiansyah Putra ◽  
Try Febrianto ◽  
Aidil Fadhli Ilhamdy
Keyword(s):  
Seasonal Changes ◽  
Growth Parameters ◽  
Water Dynamics ◽  
Percentage Cover ◽  
Food Ingredients ◽  
Factors Affecting ◽  
Average Value ◽  
Stolon Length ◽  
Different Seasons ◽  
Natural Productivity

Caulerva racemosa seaweed is a superior commodity with both ecological and socio-economical benefits. It is technologically developed into different products which include antioxidants, antibiotics, medicinal ingredients, cosmetics as well as other organic products and also used conventionally as food ingredients for human’s consumption. Meanwhile, the presence of C. racemosa is observed to decrease as the exploitation rate is one of the factors affecting its stock in the nature. Changes in environmental conditions contribute majorly to its availability in aquatic ecosystems. Furthermore, natural factors in the form of seasonal changes that cause fluctuations in water dynamics are the main focus affecting its lifespan. The results showed that C. racemosa growth parameters, which include percentage cover, productivity, together with morphometrics, failed to be significantly affected by seasonal changes. Meanwhile, the highest percentage cover was found during the northern monsoon, which has an average value of 37.99 ± 7.67 (Average±STDEV), while the lowest was during the eastern monsoons with 28.03 ± 9.09 respectively. The best morphometric size was during the northern monsoon with a tallus dimension of 0.25 with an average of 0.201 ± 0.03 and length of 0.825 ± 0.16, a stolon length of 2.09 with an average of 1.95 ± 0.08, 9 stolon grains with an average of 8 ± 0.2. However, the grain diameter, as well as the biomass, was 0.85 gr and 0.054 gr with an average of 0.825 ± 0.22 gr and the grain biomass was with an average of 0.040 ± 0.01 and 0.041 gr with the best average stolon was 0.031 ± 0.01 g in the western season. The results showed that C. racemosa, which grows up in different seasons, having its highest productivity during the northern season and the lowest one was during the eastern season with an average value of 0.439 ± 0.36 kg/m2 as well as 0.326 ± 0.37 Kg/m2, respectively

scholarly journals Influence of seasonal changes on the karyotype stability of Ukrainian Black and White dairy cows

2020 ◽  
Vol 22 (93) ◽  
pp. 29-34
Author(s):  
N. Y. Temekh ◽  
L. F. Starodub
Keyword(s):  
Seasonal Changes ◽  
Age Groups ◽  
Summer Season ◽  
Black And White ◽  
Structural Disorders ◽  
Different Seasons ◽  
The Stability ◽  
The Impact ◽  
Dairy Breed ◽  
Karyotype Stability

Of the total dairy cattle, 49 % belong to the Ukrainian black-and-white dairy breed. Animals are demanding to the conditions of detention, so the aim of the study was to study the impact of seasonal changes in the environment on the stability of the karyotype of cows of three age groups (first-born, adult and cows 8–10 years). The variability of the karyotype of the studied animals in different seasons of the year was manifested in the form of quantitative and structural disorders of chromosomes. Of the total dairy cattle, 49 % belong to the Ukrainian black-and-white dairy breed. Animals are demanding to the conditions of detention, so the aim of the study was to study the impact of seasonal changes in the environment on the stability of the karyotype of cows of three age groups (first-born, adult and cows 8–10 years). The variability of the karyotype of the studied animals in different seasons of the year was manifested in the form of quantitative and structural disorders of chromosomes. In primiparous women, the most pronounced genomic variability (aneuploidy) was observed in summer and winter and was 16.4 % and 8.8 %. In summer, this variability was more than twice the limit of spontaneous chromosomal variability. The highest percentage of structural chromosome abnormalities (chromosomal breaks) in cows of three age groups was observed in winter and was 2.5 %, 2.8 %, 3.0 %, respectively, and did not exceed the limit of spontaneous mutagenesis characteristic of cattle. An increased proportion of lymphocytes with a micronucleus in first-borns and cows aged 8–10 years (5.6 ‰, 6.4 ‰, respectively) was observed in the summer. The increased proportion of dinuclear lymphocytes appeared in the first-born in the summer season and amounted to 7.6 ‰ (at P > 0.99), and in cows 8–10 years, this variability in the summer season was 6.2 ‰, in winter – 6.7 ‰ with a statistically significant difference (P > 0.95) between the spontaneous level of cytogenetic variability. The association between karyotype stability of the studied animals and seasonal environmental factors was determined using a correlation coefficient (r). A significant positive correlation was found between aneuploidy and air temperature in primiparous and cows aged 8–10 years, relative humidity, precipitation and wind strength and chromosomal gaps in primiparous and adult cows, atmospheric pressure, relative humidity and asynchronous divergence. in adult cows and cows aged 8–10 years. A positive reliable associative dependence of the appearance of micronucleus lymphocytes and dinuclear lymphocytes on the amount of precipitation and wind strength in this area in primiparous and adult cows was established.

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