scholarly journals Deep-Sea Coral and Sponge Taxa Increase Demersal Fish Diversity and the Probability of Fish Presence

2020 ◽  
Vol 7 ◽  
Author(s):  
Mark J. Henderson ◽  
David D. Huff ◽  
Mary M. Yoklavich
Keyword(s):  
Logistic Regression ◽  
Deep Sea ◽  
Coral Cover ◽  
Demersal Fish ◽  
Weight Of Evidence ◽  
Fish Diversity ◽  
Lophelia Pertusa ◽  
Ecological Correlates ◽  
Fish Habitats ◽  
Demersal Fishes

Fishes are known to use deep-sea coral and sponge (DSCS) species as habitat, but it is uncertain whether this relationship is facultative (circumstantial and not restricted to a particular function) or obligate (necessary to sustain fish populations). To explore whether DSCS provide essential habitats for demersal fishes, we analyzed 10 years of submersible survey video transect data, documenting the locations and abundance of DSCS and demersal fishes in the Southern California Bight (SCB). We first classified the different habitats in which fishes and DSCS taxa occurred using cluster analysis, which revealed four distinct DSCS assemblages based on depth and substratum. We then used logistic regression and gradient forest analysis to identify the ecological correlates most associated with the presence of rockfish taxa (Sebastes spp.) and biodiversity. After accounting for spatial autocorrelation, the factors most related to the presence of rockfishes were depth, coral height, and the abundance of a few key DSCS taxa. Of particular interest, we found that young-of-the-year rockfishes were more likely to be present in locations with taller coral and increased densities of Plumarella longispina, Lophelia pertusa, and two sponge taxa. This suggests these DSCS taxa may serve as important rearing habitat for rockfishes. Similarly, the gradient forest analysis found the most important ecological correlates for fish biodiversity were depth, coral cover, coral height, and a subset of DSCS taxa. Of the 10 top-ranked DSCS taxa in the gradient forest (out of 39 potential DSCS taxa), 6 also were associated with increased probability of fish presence in the logistic regression. The weight of evidence from these multiple analytical methods suggests that this subset of DSCS taxa are important fish habitats. In this paper we describe methods to characterize demersal communities and highlight which DSCS taxa provide habitat to demersal fishes, which is valuable information to fisheries agencies tasked to manage these fishes and their essential habitats.

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.

scholarly journals Nonstationary Responses of Demersal Fishes to Environmental Variations in Temperate Waters of the Northwestern North Pacific under a Changing Climate

Fishes ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 22
Author(s):  
Qingsong He ◽  
Shuyang Ma ◽  
Qinwang Xing ◽  
Wenchao Zhang ◽  
Haiqing Yu ◽  
...  
Keyword(s):  
North Pacific ◽  
Negative Relationship ◽  
Demersal Fish ◽  
Fishing Effort ◽  
Asian Winter Monsoon ◽  
Changing Climate ◽  
Sst Variability ◽  
Environmental Variations ◽  
The Impact ◽  
Demersal Fishes

Although nonstationarity in marine ecosystems has attracted great attention, the nonstationary responses of demersal fishes to environmental variations induced by the changing climate are still not well understood. Here, we collected 21 time series of demersal fishes from 1956 to 2015 to investigate the climate-induced nonstationary responses in temperate waters of the northwestern North Pacific (NWP). We showed that these demersal fishes experienced state shifts in approximately 1986/87, accompanied by abrupt warming over this region. Moreover, the relationships between demersal fishes and sea surface temperature (SST) were found to change between the two identified eras (i.e., a weak relationship before 1986 and a strong negative relationship after 1986), which may be primarily caused by the alternating dominance of the East Asian winter monsoon and mega-ENSO on SST in temperate waters of the NWP. The identified climate-induced nonstationary responses of demersal fishes to SST variability in this study may provide implications for understanding climate-induced biological dynamics, predicting demersal fish fluctuations, coping with potential ecological risks, and the sustainable exploitation of fishery resources in the future climate. Note that the impact of fishing on the demersal fishes in temperate waters of the NWP was not assessed in this study due to the lack of fishing effort data and therefore the conclusions of our research should be approached with caution.

scholarly journals Pengaruh umpan buatan warna merah dan kuning terhadap hasil tangkapan pancing pompa di perairan pantai Desa Bajo, Kabupaten Minahasa Selatan

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Hermanus B. Usili ◽  
Ivor L. Labaro ◽  
Mariana E. Kayadoe
Keyword(s):  
Reef Fishes ◽  
Experimental Methods ◽  
Demersal Fish ◽  
Fishing Gear ◽  
Traditional Fishing ◽  
Demersal Fishes ◽  
Parrot Fish

ABSTRACT Pump handline is a traditional fishing gear commonly used by fishermen in the Gulf Amurang to catch demersal fishes/reef fishes. This handline uses artificial baits made of fiber cloth of different colors, and an effective bait color is unknown yet. This research aims to study the effect of artificial bait colors on the pump handline catches, and to identify the species. This research was conducted through experimental methods by operating four pump handline units using red and yellow artificial baits starting at 07:00 am until 14:00 pm. The catches were 33 fishes, consisting of 23 fishes caught with red baits and 10 fishes caught with yellow baits. The results showed that red and yellow artificial baits on the pump handline had different number of catches, the average catches per hour of the respective bait colors were 3.83 (4 fishes) and 1.67 (2 fishes). The catch species consisted of 17 species, and was predominated by groupers, parrot fish, snappers and goat fish. Keywords: pump handline, artificial bait, demersal fish/reef fishes.   ABSTRAK Pancing pompa merupakan alat tangkap ikan tradisional yang umum dioperasikan oleh nelayan di Teluk Amurang untuk menangkap jenis-jenis ikan demersal/ikan-ikan karang. Umpan yang digunakan adalah umpan buatan dari serat kain yang warnanya bervariasi, dan warna umpan yang efektif belum diketahui. Sehingga tujuan penelitian ialah mempelajari pengaruh warna umpan buatan terhadap hasil tangkapan pancing pompa dan mengidentifikasi jenis-jenis ikan yang tertangkap. Penelitian ini dilakukan melalui metode eksperimental dengan mengoperasikan empat unit pancing pompa yang menggunakan umpan buatan warna merah dan kuning pada pukul 07.00 hingga pukul 14:00 Wita. Hasil tangkapan yang diperoleh berjumlah 33 ekor ikan, terdiri dari 23 ekor tertangkap dengan umpan buatan warna merah dan 10 ekor tertangkap dengan umpan buatan warna kuning. Hasil analisis menyimpulkan bahwa umpan buatan warna merah dan warna kuning pada pancing pompa ternyata berbeda, karena umpan warna merah mendapatkan hasil rata-rata 3,83 (4 ekor) per jam, sedangkan umpan warna kuning rata-rata 1,67 (2 ekor) per jam. Jenis-jenis ikan yang tertangkap dengan pancing pompa terdiri dari 17 spesies, dan didominasi oleh goropa, kakatua, gorara dan biji nangka. Kata-kata kunci: pancingpompa,  umpan buatan, ikandemersal/ikankarang

scholarly journals Landslide Susceptibility Mapping Using Statistical Methods along the Asian Highway, Bhutan

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 430 ◽  
Author(s):  
Sangey Pasang ◽  
Petr Kubíček
Keyword(s):  
Logistic Regression ◽  
Landslide Susceptibility ◽  
Area Under The Curve ◽  
Information Value ◽  
Weight Of Evidence ◽  
Regression Methods ◽  
Susceptibility Maps ◽  
Road Corridors ◽  
Landslide Susceptibility Maps ◽  
Control Samples

In areas prone to frequent landslides, the use of landslide susceptibility maps can greatly aid in the decision-making process of the socio-economic development plans of the area. Landslide susceptibility maps are generally developed using statistical methods and geographic information systems. In the present study, landslide susceptibility along road corridors was considered, since the anthropogenic impacts along a road in a mountainous country remain uniform and are mainly due to road construction. Therefore, we generated landslide susceptibility maps along 80.9 km of the Asian Highway (AH48) in Bhutan using the information value, weight of evidence, and logistic regression methods. These methods have been used independently by some researchers to produce landslide susceptibility maps, but no comparative analysis of these methods with a focus on road corridors is available. The factors contributing to landslides considered in the study are land cover, lithology, elevation, proximity to roads, drainage, and fault lines, aspect, and slope angle. The validation of the method performance was carried out by using the area under the curve of the receiver operating characteristic on training and control samples. The area under the curve values of the control samples were 0.883, 0.882, and 0.88 for the information value, weight of evidence, and logistic regression models, respectively, which indicates that all models were capable of producing reliable landslide susceptibility maps. In addition, when overlaid on the generated landslide susceptibility maps, 89.3%, 85.6%, and 72.2% of the control landslide samples were found to be in higher-susceptibility areas for the information value, weight of evidence, and logistic regression methods, respectively. From these findings, we conclude that the information value method has a better predictive performance than the other methods used in the present study. The landslide susceptibility maps produced in the study could be useful to road engineers in planning landslide prevention and mitigation works along the highway.

scholarly journals Landslide Susceptibility Mapping for the Muchuan County (China): A Comparison Between Bivariate Statistical Models (WoE, EBF, and IoE) and Their Ensembles with Logistic Regression

Symmetry ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 762 ◽  
Author(s):  
Renwei Li ◽  
Nianqin Wang
Keyword(s):  
Land Use ◽  
Logistic Regression ◽  
Statistical Models ◽  
Landslide Susceptibility ◽  
Slope Angle ◽  
Susceptibility Mapping ◽  
Aerial Photographs ◽  
Weight Of Evidence ◽  
Landslide Susceptibility Mapping ◽  
Topographic Wetness Index

The main purpose of this study is to apply three bivariate statistical models, namely weight of evidence (WoE), evidence belief function (EBF) and index of entropy (IoE), and their ensembles with logistic regression (LR) for landslide susceptibility mapping in Muchuan County, China. First, a landslide inventory map contained 279 landslides was obtained through the field investigation and interpretation of aerial photographs. Next, the landslides were randomly divided into two parts for training and validation with the ratio of 70/30. In addition, according to the regional geological environment characteristics, twelve landslide conditioning factors were selected, including altitude, plan curvature, profile curvature, slope angle, distance to roads, distance to rivers, topographic wetness index (TWI), normalized different vegetation index (NDVI), land use, soil, and lithology. Subsequently, the landslide susceptibility mapping was carried out by the above models. Eventually, the accuracy of this research was validated by the area under the receiver operating characteristic (ROC) curve and the results indicated that the landslide susceptibility map produced by EBF-LR model has the highest accuracy (0.826), followed by IoE-LR model (0.825), WoE-LR model (0.792), EBF model (0.791), IoE model (0.778), and WoE model (0.753). The results of this study can provide references of landslide prevention and land use planning for local government.

The effect of marine seismic surveys on the movement, abundance and community structure of demersal fish assemblages on the North West Shelf

2020 ◽  
Vol 60 (2) ◽  
pp. 480
Author(s):  
Mark G. Meekan ◽  
Conrad W. Speed ◽  
Robert D. McCauley ◽  
Jayson M. Semmens ◽  
Stephen J. Newman ◽  
...  
Keyword(s):  
Fish Assemblages ◽  
Demersal Fish ◽  
Seismic Survey ◽  
Survey Study ◽  
Control Zone ◽  
High Exposure ◽  
North West ◽  
Air Gun ◽  
Study Results ◽  
Demersal Fishes

In 2018, the Australian Institute of Marine Science (AIMS) and its partners, conducted an experiment to investigate the effect of exposure to a 3D seismic survey on demersal fishes. The experiment involved the use of a commercial seismic vessel equipped with a 2600 cubic inch air-gun array, sailing a racetrack pattern with eight operational (high exposure zone) and eight inactive (vessel control zone) sail lines, with a 500 m sequential line separation and ≈18 m shot point spacing. The high exposure and vessel control lines were separated by 35 km. Demersal fishes were observed in five sampling surveys over a 6-month period (three surveys before and two after exposure), using acoustic telemetry and stereo baited remote underwater videos systems (BRUVS). The telemetry component included the capture, tagging with acoustic transmitters and release of 387 red emperor (Lutjanus sebae) within two telemetry receiver arrays. These arrays, one in each zone, comprised 37 and 39 acoustic receivers over ≈32 km2, to record movements of tagged fish. The receivers provided near-continuous data on tag locations, and, hence, movement of fish in the area, until removal in December 2018. During each sampling survey, BRUVS were deployed at various distances from the area of the seismic survey. Study results are currently being finalised for presentation.

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