Monitoring demersal scalefish populations in the Browse Basin region: accounting for spatial variability and detecting change in key fish populations

2017 ◽  
Vol 57 (2) ◽  
pp. 382
Author(s):  
Russ Babcock ◽  
Emma Lawrence ◽  
Tonya van der Velde ◽  
C. Roland Pitcher ◽  
Mark Tonks ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Relative Abundance ◽  
Fish Assemblages ◽  
Environmental Data ◽  
Fish Distribution ◽  
Distribution Data ◽  
Important Species ◽  
Fish Traps ◽  
Commercial Species ◽  
Basin Region

One of the objectives of the Applied Research Program (ARP), funded by Shell and the INPEX-operated Ichthys LNG Project, was to establish the basis for evaluating the effects of any potential oil spill from the Prelude or Ichthys fields on populations of commercially important demersal fishes in the Northern Demersal Scalefish Managed Fishery. The ARP has delivered improved baseline understanding of the status and spatial variability in populations of commercially and ecologically important finfish of the Browse Basin region, in the vicinity of the Prelude and Ichthys fields, using both commercial-style fish traps and baited remote underwater videos (BRUVs) as sampling methods. We used available environmental-data layers and fish-distribution data, in combination with modelled plume projections, to design a study such that sites were balanced with respect to fish habitat and likely affected and unaffected zones. The sampling-design employed was statistically effective with power to show changes in fish assemblages, and relative abundance of as little as 30% could be detected with 80% certainty in the main commercial species, goldband snapper (Pristipomoides multidens), using BRUVs. For the second-most important species, red emperor (Lutjanus sebae), a larger decline of 50% would have to occur for this change to be determined with the same level of confidence. Traps were a more powerful tool for sampling L. sebae, allowing a 40% change to be detected; however, for all other species BRUVs were more powerful. Sampling of the demersal-fish assemblages surrounding the Prelude and Ichthys fields by using both fish traps and BRUVs demonstrated the feasibility of detecting change in the relative abundance of the fish assemblage as well as in the key commercial species.

Aquatic and semi aquatic Hemiptera community of Sonebeel, the largest wetland of Assam, northeastern India

2018 ◽  
Vol 10 (13) ◽  
pp. 12792-12799
Author(s):  
Anupama Saha ◽  
Susmita Gupta
Keyword(s):  
Species Richness ◽  
Pest Control ◽  
Relative Abundance ◽  
Species Distribution ◽  
Diversity Indices ◽  
Environmental Data ◽  
Northeastern India ◽  
Ecological Roles

Aquatic and semiaquatic Hemiptera bugs play significant ecological roles, and they are important indicators and pest control agents.  Little information is currently available concerning its populations in southern Assam.  This study assessed hemipterans in four sites of Sonebeel, the largest wetland in Assam (3458.12 ha at full storage level), situated in Karimganj District.  The major inflow and outflow of the wetland are the rivers Singla and Kachua, respectively (the Kachua drains into the Kushiyara River).  Samples were trapped with pond nets and were seasonally recorded.  This study recorded a total of 28 species of aquatic and semiaquatic hemipterans belonging to 20 genera under nine families.  Population, geographical and environmental data (e.g., rainfall) were used to assess the relative abundance of species, species richness and different diversity indices, and species distribution. 

scholarly journals Islands in the desert: environmental distribution modelling of endemic flora reveals the extent of Pleistocene tropical relict vegetation in southern Arabia

2019 ◽  
Vol 124 (3) ◽  
pp. 411-422 ◽  
Author(s):  
James S Borrell ◽  
Ghudaina Al Issaey ◽  
Darach A Lupton ◽  
Thomas Starnes ◽  
Abdulrahman Al Hinai ◽  
...  
Keyword(s):  
Environmental Variables ◽  
Narrow Range ◽  
Biodiversity Hotspot ◽  
Environmental Data ◽  
Distribution Data ◽  
Endemic Plants ◽  
Environmental Niche ◽  
Environmental Distribution ◽  
Southern Arabia ◽  
Endemic Flora

AbstractBackground and AimsSouthern Arabia is a global biodiversity hotspot with a high proportion of endemic desert-adapted plants. Here we examine evidence for a Pleistocene climate refugium in the southern Central Desert of Oman, and its role in driving biogeographical patterns of endemism.MethodsDistribution data for seven narrow-range endemic plants were collected systematically across 195 quadrats, together with incidental and historic records. Important environmental variables relevant to arid coastal areas, including night-time fog and cloud cover, were developed for the study area. Environmental niche models using presence/absence data were built and tuned for each species, and spatial overlap was examined.Key ResultsA region of the Jiddat Al Arkad reported independent high model suitability for all species. Examination of environmental data across southern Oman indicates that the Jiddat Al Arkad displays a regionally unique climate with higher intra-annual stability, due in part to the influence of the southern monsoon. Despite this, the relative importance of environmental variables was highly differentiated among species, suggesting that characteristic variables such as coastal fog are not major cross-species predictors at this scale.ConclusionsThe co-occurrence of a high number of endemic study species within a narrow monsoon-influenced region is indicative of a refugium with low climate change velocity. Combined with climate analysis, our findings provide strong evidence for a southern Arabian Pleistocene refugium in Oman’s Central Desert. We suggest that this refugium has acted as an isolated temperate and mesic island in the desert, resulting in the evolution of these narrow-range endemic flora. Based on the composition of species, this system may represent the northernmost remnant of a continuous belt of mesic vegetation formerly ranging from Africa to Asia, with close links to the flora of East Africa. This has significant implications for future conservation of endemic plants in an arid biodiversity hotspot.

Use of stereo baited remote underwater video systems to estimate the presence and size of white sharks (Carcharodon carcharias)

2017 ◽  
Vol 68 (7) ◽  
pp. 1391 ◽  
Author(s):  
D. Harasti ◽  
K. A. Lee ◽  
R. Laird ◽  
R. Bradford ◽  
B. Bruce
Keyword(s):  
Relative Abundance ◽  
Fish Assemblages ◽  
New South ◽  
Underwater Video ◽  
Carcharodon Carcharias ◽  
South Wales ◽  
Video Systems ◽  
Near Shore ◽  
Number Of Individuals ◽  
Non Destructive

Stereo baited remote underwater video systems (stereo-BRUVs) are commonly used to assess fish assemblages and, more recently, to record the localised abundance and size of sharks. The present study investigated the occurrence and size of white sharks (Carcharodon carcharias) in the near-shore environment off Bennett’s Beach, part of a known nursery area for the species in central New South Wales, Australia. Six stereo-BRUV units were deployed approximately fortnightly between August and December 2015 for periods of 5h in depths of 7–14m. Stereo-BRUVs successfully recorded 34 separate sightings of 22 individual white sharks. The highest number of individuals detected during a single day survey was eight. All C. carcharias observed on stereo-BRUVs were juveniles ranging in size from 1.50 to 2.46-m total length (mean±s.e., 1.91±0.05m; n=22). The time to first appearance ranged from 15 to 299min (mean±s.e., 148±15min). This study demonstrates that the use of stereo-BRUVs is a viable, non-destructive method to obtain estimates of the size and presence of white sharks, and may be useful in estimating relative abundance in near-shore environments where white sharks are known to frequent.

Historical Changes in Large River Fish Assemblages of the Americas

2005 ◽  
Keyword(s):  
Relative Abundance ◽  
Mississippi River ◽  
Largemouth Bass ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Micropterus Salmoides ◽  
Lepomis Macrochirus ◽  
Large River ◽  
Frequency Of Occurrence ◽  
Abundance And Distribution

<em>Abstract.</em>—An investigation of historical fisheries information for pools 4–13 of the upper Mississippi River (UMR) was conducted to 1) determine the pre-1938 relative abundance and distribution of bluegill <em>Lepomis macrochirus </em>and largemouth bass <em>Micropterus salmoides, </em>2) determine the composition and relative abundance of the preimpoundment fish assemblage, and 3) determine if a shift in frequency of occurrence and relative abundance has occurred due to impoundment.

scholarly journals Fish assemblages in a coastal bay adjacent to a network of marine protected areas in southern Brazil

2016 ◽  
Vol 64 (3) ◽  
pp. 295-308 ◽  
Author(s):  
André Pereira Cattani ◽  
Fábio Gonçalves Daura Jorge ◽  
Gisela Costa Ribeiro ◽  
Leonardo Liberali Wedekin ◽  
Paulo César de Azevedo Simões Lopes ◽  
...  
Keyword(s):  
Protected Areas ◽  
Marine Protected Areas ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Fish Fauna ◽  
Abundant Species ◽  
Environmental Data ◽  
Fish Assemblage Structure ◽  
Principal Coordinates ◽  
Coastal Bay

Abstract Baía Norte (North Bay) in Santa Catarina State is considered a typical coastal bay and is surrounded by a network of Marine Protected Areas. The objectives of this study were to describe the composition of the demersal fish assemblage, identify seasonal and spatial structures on a fine scale and evaluate the role of habitat descriptors and abiotic variables affecting the fish assemblage structure. Seasonal samplings were conducted in 2005, using bottom trawls in six pre-established areas in Baía Norte in summer, fall, winter and spring. Simultaneously with each trawl, environmental data were collected with a multiparameter probe. Temporal and spatial differences in fish abundance were tested by a PERMANOVA. To illustratethe differences detected graphically we ran a canonical analysis of principal coordinates (CAP). The influence of environmental variables on the fish fauna was evaluated using a Distant Based Linear Model (DistLM) with Akaike's information criterion (AIC). A total of 9,888 specimens, distributed in 27 families and 62 species, were collected. Citharichthys spilopterus was the most abundant species. PERMANOVA detected differences for abundance between seasons, areas and interaction among all the factors. The DISTLM selected temperature and pH. The results highlight seasonality as an important factor in the structuring of fish fauna of the study place.

Examining Local Transferability of Predictive Species Distribution Models for Invasive Plants: An Example with Cogongrass (Imperata cylindrica)

2011 ◽  
Vol 4 (4) ◽  
pp. 390-401 ◽  
Author(s):  
Gary N. Ervin ◽  
D. Christopher Holly
Keyword(s):  
Invasive Species ◽  
Species Distribution ◽  
Species Distribution Models ◽  
Imperata Cylindrica ◽  
Environmental Data ◽  
Training Data ◽  
Distribution Data ◽  
Strongly Correlated ◽  
Distribution Models ◽  
Tree Canopy Cover

AbstractSpecies distribution modeling is a tool that is gaining widespread use in the projection of future distributions of invasive species and has important potential as a tool for monitoring invasive species spread. However, the transferability of models from one area to another has been inadequately investigated. This study aimed to determine the degree to which species distribution models (SDMs) for cogongrass, developed with distribution data from Mississippi (USA), could be applied to a similar area in neighboring Alabama. Cogongrass distribution data collected in Mississippi were used to train an SDM that was then tested for accuracy and transferability with cogongrass distribution data collected by a forest management company in Alabama. Analyses indicated the SDM had a relatively high predictive ability within the region of the training data but had poor transferability to the Alabama data. Analysis of the Alabama data, via independent SDM development, indicated that predicted cogongrass distribution in Alabama was more strongly correlated with soil variables than was the case in Mississippi, where the SDM was most strongly correlated with tree canopy cover. Results suggest that model transferability is influenced strongly by (1) data collection methods, (2) landscape context of the survey data, and (3) variations in qualitative aspects of environmental data used in model development.

Spatial and temporal variation in assemblages of Lutjanidae, Lethrinidae and associated fish species among mid-continental shelf reefs in the central Great Barrier Reef

2001 ◽  
Vol 52 (6) ◽  
pp. 843 ◽  
Author(s):  
Stephen J. Newman ◽  
David McB. Williams
Keyword(s):  
Continental Shelf ◽  
Temporal Variation ◽  
Fish Assemblages ◽  
Spatial And Temporal Variation ◽  
Shallow Trap ◽  
Fish Traps ◽  
Lutjanus Carponotatus ◽  
Plectropomus Leopardus ◽  
Trap Catches ◽  
Over Time

Visual censuses were used to survey shallow-water assemblages of the Lutjanidae and Lethrinidae among three mid-continental shelf reefs, and fish traps were used to survey deeper water assemblages below diveable depths. Significant differences were found in visual censuses of the Lutjanidae and Lethrinidae among reefs. Trap catches of the Lutjanidae and Lethrinidae varied more between depths and diel sampling periods than among reefs or over time. Lutjanus carponotatus, L. fulviflamma and Lethrinus miniatus were more abundant in shallow trap sets, whereas Lutjanus adetii, L. russelli, L. sebae, L. vitta, Gymnocranius audleyi, Lethrinus sp.2 and Abalistes stellaris were more abundant in deeper sets. Additionally, Lutjanus adetii, L. fulviflamma, L. quinquelineatus, L. russelli, L. sebae, L. vitta and Lethrinus miniatus were more abundant at night, whereas Lethrinus sp. 2, Abalistes stellarisand Plectropomus leopardus were more abundant during the day. The absence of significant temporal variation in the observed spatial patterns both among reefs and between depths indicates that these patterns may persist through time. The use of both visual censuses and fish traps to assess reef fish assemblages may provide an objective way of repeatedly censusing reefs for monitoring purposes, especially where differences among reefs and regions are important.

Spatial variability of helminth parasites and evidence for stock discrimination in the round sardinella, Sardinella aurita (Valenciennes, 1847), off the coast of Tunisia

2015 ◽  
Vol 90 (3) ◽  
pp. 353-358 ◽  
Author(s):  
M. Feki ◽  
M. Châari ◽  
L. Neifar
Keyword(s):  
Spatial Variability ◽  
Helminth Parasites ◽  
Important Species ◽  
Tunisian Coast ◽  
The North ◽  
Stock Discrimination ◽  
Discriminant Analyses ◽  
Inshore Waters ◽  
Sardinella Aurita ◽  
Biological Tags

AbstractThree digeneans – Parahemiurus merus (Linton, 1910), Aphanurus stossichii (Monticelli, 1891) and Lecithochirium sp. – and one tetraphyllidean cestode larva were used as biological tags to discriminate the stock of Sardinella aurita (Valenciennes, 1847). In total, 579 fish were examined in five zones off the Tunisian coast, including Bizerte and Kelibia in the north, Mahdia in the east, Gabes and Zarzis in the south. Discriminant analyses used for the separation of S. aurita allowed for the identification of two discrete stocks. Sardinella aurita from Bizerte, Kelibia and Zarzis clumped together as a single stock. Parahemiurus merus and A. stossichii were the most important species in determining the location of sampled fish from these regions. Specimens from Mahdia and Gabes were grouped as one stock characterized by the presence of Lecithochirium sp. and larvae of the Tetraphyllidea. These results were corroborated by comparing the parameters of prevalence and mean abundance of parasites among zones. The separation of S. aurita between localities after pooling specimens from Bizerte, Kelibia and Zarzis and separately pooling those from Mahdia and Gabes also allowed the identification of two discrete stocks, one in offshore waters from Bizerte, Kelibia and Zarzis characterized by the digeneans P. merus and A. stossichii and one in inshore waters from Mahdia and Gabes characterized by Lechithochirium sp. and tetraphyllidean larvae.

Distribution, abundance, and diversity of stream fishes under variable environmental conditions

2006 ◽  
Vol 63 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Christopher M Taylor ◽  
Thomas L Holder ◽  
Riccardo A Fiorillo ◽  
Lance R Williams ◽  
R Brent Thomas ◽  
...  
Keyword(s):  
Species Richness ◽  
Environmental Conditions ◽  
Community Dynamics ◽  
Local Community ◽  
Fish Assemblages ◽  
Fish Distribution ◽  
Stream Fish ◽  
Spatial And Temporal Variability ◽  
Regional Patterns ◽  
Abundance And Diversity

The effects of stream size and flow regime on spatial and temporal variability of stream fish distribution, abundance, and diversity patterns were investigated. Assemblage variability and species richness were each significantly associated with a complex environmental gradient contrasting smaller, hydrologically variable stream localities with larger localities characterized by more stable flow regimes. Assemblages showing the least variability were the most species-rich and occurred in relatively large, stable environments. Theory suggests that species richness can be an important determinant of assemblage variability. Although this appears to be true in our system, we suggest that spatial and temporal heterogeneity in the environment largely determines both assemblage richness and variability, providing a more parsimonious explanation for the diversity–variability correlation. Changes in species richness of local assemblages across time were coordinated across the landscape, and assemblages formed spatially and temporally nested subset patterns. These results suggest an important link between local community dynamics and community-wide occurrence. At the species level, mean local persistence was significantly associated with regional occurrence. Thus, the more widespread a species was, the greater its local persistence. Our results illustrate how the integrity of local stream fish assemblages is dependent on local environmental conditions, regional patterns of species distribution, and landscape continuity.

Does habitat or depth influence catch rates of pelagic species?

2007 ◽  
Vol 64 (11) ◽  
pp. 1581-1594 ◽  
Author(s):  
Keith A Bigelow ◽  
Mark N Maunder
Keyword(s):  
Relative Abundance ◽  
Environmental Conditions ◽  
Environmental Data ◽  
Catch Per Unit Effort ◽  
Blue Shark ◽  
Species Vulnerability ◽  
Thunnus Obesus ◽  
Catch Rates ◽  
The Relationship ◽  
The Vertical Distribution

The efficiency of a pelagic longline fishing operation and the species composition of the resulting catch is influenced primarily by the relationship between the distribution of hooks and species vulnerability, with vulnerability described by either depth or some suite of environmental variables. We therefore fitted longline catch rate models to determine whether catch is estimated better by vertically distributing a species by depth or by environmental conditions (e.g., temperature, thermocline gradient, and oxygen concentration). Catch rates were estimated by two methods: (i) monitoring longlines where the vertical distribution of hooks and catch in relation to depth and environmental conditions is known, and (ii) applying a statistical habitat-based standardization (statHBS) model to fishery and environmental data to develop relative abundance indices for bigeye tuna (Thunnus obesus) and blue shark (Prionace glauca). Results indicated that an understanding of gear dynamics and environmental influences are important for analyzing catch-per-unit-effort (CPUE) data correctly. Analyses based on depth-specific catch rates can lead to serious misinterpretation of abundance trends, despite the use of sophisticated statistical techniques (e.g., generalized linear mixed models). This illustrates that inappropriate inclusion or exclusion of important covariates can bias estimates of relative abundance, which may be a common occurrence in CPUE analysis.

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