scholarly journals Variability in the density and sound-speed of coastal zooplankton and nekton

2009 ◽  
Vol 67 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Krissy A. Forman ◽  
Joseph D. Warren
Keyword(s):  
Sound Speed ◽  
Fundulus Heteroclitus ◽  
Acoustic Scattering ◽  
Large Area ◽  
Palaemonetes Pugio ◽  
Acoustic Data ◽  
Abundance Estimates ◽  
Short Period ◽  
Crangon Septemspinosa ◽  
Animal Size

Abstract Forman, K. A., and Warren, J. D. 2010. Variability in the density and sound-speed of coastal zooplankton and nekton. – ICES Journal of Marine Science, 67: 10–18. Acoustic sampling techniques provide an advantage over traditional net-sampling by increasing scientist ability to survey a large area in a relatively short period, as well as providing higher-resolution data in the vertical and horizontal dimensions. To convert acoustic data into measures of biological organisms, physics-based scattering models are often used. Such models use several parameters to predict the amount of sound scattered by a fluid-like or weakly scattering animal. Two important input parameters are the density (g) and sound-speed (h) contrasts of the animal and the surrounding seawater. The density and sound-speed contrasts were measured for coastal zooplankton and nekton species including shrimps (Palaemonetes pugio and Crangon septemspinosa), fish (Fundulus majalis and Fundulus heteroclitus), and polychaetes (Nereis succinea and Glycera americana) along with multiple physiological and environmental variables. Factors such as animal size, feeding status, fecundity, gender, and maturity caused variations in g. The variations in g observed for these animals could lead to large differences (or uncertainties) in abundance estimates based on acoustic scattering models and field-collected backscatter data. It may be important to use a range of values for g and h in the acoustic scattering models used to convert acoustic data into estimates of the abundance of marine organisms.

A multifrequency method to classify and evaluate fisheries acoustics data

2006 ◽  
Vol 63 (10) ◽  
pp. 2225-2235 ◽  
Author(s):  
J Michael Jech ◽  
William L Michaels
Keyword(s):  
Clupea Harengus ◽  
Biological Information ◽  
Classification Algorithms ◽  
Atlantic Herring ◽  
Population Abundance ◽  
Acoustic Data ◽  
Video Images ◽  
Abundance Estimates ◽  
Fisheries Acoustics ◽  
Acoustic Surveys

Acoustic surveys have been conducted on Georges Bank from 1998 to present to estimate Atlantic herring (Clupea harengus) population abundance. Acoustic data were collected with a 12 or 18, 38, and 120 kHz Simrad EK500 scientific echo sounder. A pelagic trawl and underwater video images were used to collect biological information and to verify the species composition of acoustic backscatter. A multifrequency classification method was developed to improve the efficiency and accuracy of classifying species from acoustic echograms. In this method, a volume backscatter (Sv) threshold was applied equivalently to all echograms, and then a composite echogram was created based on which frequencies had Sv greater than or less than the Sv threshold. The results of this method were compared with the standard method of visually scrutinizing regions, and metrics were developed to evaluate the accuracy of classification algorithms relative to current methods, as well as to assess the effects of classification methods on population abundance estimates. In general, this method matched visually scrutinized Atlantic herring regions, but with consistent biases in classifying 38 kHz backscatter. The metrics highlighted spatial and temporal changes in the acoustic landscape, which may be indicative of intra- and inter-annual biological changes.

scholarly journals Material properties of Northeast Pacific zooplankton

2014 ◽  
Vol 71 (9) ◽  
pp. 2550-2563 ◽  
Author(s):  
Kaylyn N. Becker ◽  
Joseph D. Warren
Keyword(s):  
Sound Speed ◽  
Larval Fish ◽  
Acoustic Scattering ◽  
Geographic Location ◽  
Geographic Area ◽  
Zooplankton Biomass ◽  
Density Contrast ◽  
Northeast Pacific ◽  
Dimensional Measurements ◽  
The Mean

Abstract We measured the density and sound speed contrasts relative to seawater of Northeast Pacific zooplankton. The density contrast (g) was measured for euphausiids, decapods (Sergestes similis), amphipods (Primno macropa, Phronima sp., and Hyperiid spp.), siphonophore bracts, chaetognaths, larval fish, crab megalopae, larval squid, and medusae. Morphometric data (length, width, and height) were collected for these taxa. Density contrasts varied within and between zooplankton taxa. The mean and standard deviation (s.d.) for euphausiid density contrast were 1.059 ± 0.009. Relationships between zooplankton density contrast and morphometric measurements, geographic location, and environmental conditions were investigated. Site had a significant effect on euphausiid density contrast. Density contrasts of euphausiids collected in the same geographic area ∼4–10 d apart were significantly higher (p< 0.001). Sound speed contrast (h) was measured for euphausiids and pelagic decapods (S. similis) and it varied between taxa. The mean and s.d. for euphausiid sound speed were 1.019 ± 0.009. Euphausiid mass was calculated from measured density and volume, and a relationship between euphausiid mass and length was produced. We determined that euphausiid volume could be accurately estimated from two-dimensional measurements of animal body shape, and that biomass (or biovolume) could be accurately calculated from digital photographs of animals. Data from this study can improve the accuracy of theoretical acoustic scattering models for these taxa, resulting in more accurate estimates of zooplankton biomass in this region.

scholarly journals Modelling acoustic scattering, sound speed, and attenuation in gassy soft marine sediments

2016 ◽  
Vol 140 (1) ◽  
pp. 274-282 ◽  
Author(s):  
A. Mantouka ◽  
H. Dogan ◽  
P. R. White ◽  
T. G. Leighton
Keyword(s):  
Marine Sediments ◽  
Sound Speed ◽  
Acoustic Scattering

Cadmium Poisoning in Fundulus heteroclitus (Pisces: Cyprinodontidae) and other Marine Organisms

1971 ◽  
Vol 28 (9) ◽  
pp. 1225-1234 ◽  
Author(s):  
Ronald Eisler
Keyword(s):  
Fundulus Heteroclitus ◽  
Blue Mussel ◽  
Cadmium Toxicity ◽  
Grass Shrimp ◽  
Body Burden ◽  
Marine Species ◽  
Whole Body ◽  
Urosalpinx Cinerea ◽  
Eastern Mud Snail ◽  
Crangon Septemspinosa

In acute toxicity bioassays with [Formula: see text] at 20 C and 20‰ salinity, the concentrations fatal to 50% of the organisms of various marine species in 96 hr ranged between 0.32 and 55.0 mg/liter Cd2+. The order of sensitivity was: sand shrimp, Crangon septemspinosa (0.32); hermit crab, Pagurus longicarpus (0.32); grass shrimp, Palaemonetes vulgaris (0.42); common starfish, Asterias forbesi (0.82); common soft-shell clam, Mya arenaria (2.2); green crab, Carcinus maenus (4.1); Atlantic oyster drill, Urosalpinx cinerea (6.6); eastern mud snail, Nassarius obsoletus (10.5); sandworm, Nereis virens (11.0); striped killifish, Fundulus majalis (21.0); blue mussel, Mytilus edulis (25.0); sheepshead minnow, Cyprinodon variegatus (50.0); and mummichog, Fundulus heteroclitus (55.0). Mummichogs were more susceptible to cadmium exposures at 20 C than at 5 C and at 5‰ salinity than at 15, 25, or 35‰. Additional studies with mummichogs clearly demonstrated that 96 hr was not sufficient to adequately evaluate cadmium toxicity to this species. Mummichog whole body cadmium residues determined by atomic absorption provided a useful index of cadmium body burden among fish surviving exposure. However, cadmium residue data from dead mummichogs were of limited worth owing to accumulation after death.

scholarly journals Geostatistical simulations of eastern Bering Sea walleye pollock spatial distributions, to estimate sampling precision

2007 ◽  
Vol 64 (3) ◽  
pp. 559-569 ◽  
Author(s):  
Paul D. Walline
Keyword(s):  
Bering Sea ◽  
Walleye Pollock ◽  
Geostatistical Simulation ◽  
Normal Space ◽  
Total Biomass ◽  
Spatial Distributions ◽  
Acoustic Data ◽  
Eastern Bering Sea ◽  
Abundance Estimates ◽  
Length Frequency Data

Abstract Walline, P. D. 2007. Geostatistical simulations of eastern Bering Sea walleye pollock spatial distributions, to estimate sampling precision. – ICES Journal of Marine Science, 64: 559–569. Sequential Gaussian and sequential indicator geostatistical simulation methods were used to estimate confidence intervals (CIs) for biomass estimates from six echo-integration trawl surveys of eastern Bering Sea walleye pollock (Theragra chalcogramma) biomass. Uncertainty in the acoustic and the length frequency data was combined in the calculation of CIs. Sampling in 2002 provided evidence for isotropy in the spatial distribution. Variogram models were characterized by long ranges (75–122 nautical miles for non-zero acoustic data, for example) compared with the smallest dimension of the survey area (∼100 nautical miles) and small nugget effects (∼20% of the semi-variance in transformed normal space for acoustic data). The 95% CIs obtained for the abundance estimates did not vary greatly between years and were similar to those from a one-dimensional transitive geostatistical analysis, i.e. ± 5–9% of estimated total biomass.

The effects of the parasite Probopyrus pandalicola (Packard, 1879) (Isopoda, Bopyridae) on the behavior, transparent camouflage, and predators of Palaemonetes pugio Holthuis, 1949 (Decapoda, Palaemonidae)

Crustaceana ◽  
2015 ◽  
Vol 88 (12-14) ◽  
pp. 1265-1281 ◽  
Author(s):  
Brigette A. Brinton ◽  
Mary Carla Curran
Keyword(s):  
Fundulus Heteroclitus ◽  
Grass Shrimp ◽  
Activity Budget ◽  
Palaemonetes Pugio ◽  
Black Paint ◽  
Predator Prey ◽  
Presence And Absence ◽  
Predator Preference

The bopyrid isopod Probopyrus pandalicola (Packard, 1879) is a large, noticeable, hematophagous ectoparasite of palaemonid shrimps, including the daggerblade grass shrimp Palaemonetes pugio Holthuis, 1949. Bopyrids affect grass shrimp physiology and may also affect predator-prey dynamics. The purpose of this study was to determine whether the isopod affected the behavior and/or camouflage of grass shrimp, thereby altering the predation preferences of the mummichog Fundulus heteroclitus (Linnaeus, 1766). To determine whether the isopod affected predator preference through behavioral and/or camouflage alterations, paired combinations of unparasitized, parasitized, and marked shrimp were presented to mummichogs. One branchiostegite of some of the unparasitized shrimp was marked with black paint to mimic the bopyrid parasite. Mummichog predation preference and shrimp behavior immediately prior to predation events were recorded. All shrimp behavior was classified as motionless, walking, swimming, or backward thrusting. Immediately prior to predation, parasitized shrimp swam more () and backward thrusted less () than unparasitized shrimp. Mummichogs exhibited a preference for the more active shrimp (80.7% of shrimp; ), and also for the less camouflaged (parasitized or marked) shrimp (81.5% of shrimp; ) if there was no difference in shrimp behavior. Parasitized shrimp were preferentially consumed (51/85 shrimp) when paired with unparasitized shrimp (), but not with marked shrimp (). A 30-min activity budget was created for each type of shrimp both in the presence and absence of predators; neither the parasite nor marking affected their behavior over 30 min (). The major finding of this study was that P. pandalicola affected the predation preferences of F. heteroclitus by altering the behavior and/or camouflage of the grass shrimp. Parasitization alters predator-prey dynamics by decreasing the camouflage and the frequency of backward-thrusting behavior by the host when it is threatened by predation, which thereby decreases the ability of shrimp to escape from predators.

scholarly journals Acoustic data collected during and between bottom trawl stations: consistency and common trends

2007 ◽  
Vol 64 (1) ◽  
pp. 166-180 ◽  
Author(s):  
Nicolas Bez ◽  
David Reid ◽  
Suzanna Neville ◽  
Yves Vérin ◽  
Vidar Hjellvik ◽  
...  
Keyword(s):  
Bottom Trawl ◽  
Vertical Profiles ◽  
Spatial Structures ◽  
Acoustic Measurements ◽  
Acoustic Data ◽  
Global Indices ◽  
Abundance Estimates ◽  
Before And After ◽  
Systematic Perturbation ◽  
Trawl Surveys

Acoustic data are often collected during bottom trawl surveys. Their use can potentially improve the precision and accuracy of fish abundance estimates if acoustic data collected between trawl stations are consistent with those collected during trawling operations. This question is addressed here through the analysis of 20 bottom trawl surveys (three survey areas and five different survey series) with coincident acoustic measurements during and between trawl stations. Firstly, on-station and underway acoustic data were compared using statistics computed globally over each survey (average vertical profiles, global indices of collocations, and spatial structures) for various combinations of depth layers. Secondly, we focussed on underway acoustic data recorded in the vicinity of stations, distinguishing between data recorded before and after the tows. On-station and underway acoustic data were highly consistent, and no systematic perturbation of the acoustic sign due to the presence of the gear a few hundred metres behind the vessel was observed.

scholarly journals Group IV humpback whales: their status from aerial and landbased surveys off Western Australia, 2005

2020 ◽  
pp. 223-234
Author(s):  
Charles G.M. Paxton ◽  
Sharon l. Hedley ◽  
John l. Bannister
Keyword(s):  
Aerial Survey ◽  
Group Iv ◽  
Humpback Whales ◽  
Reliable Estimate ◽  
Line Transect ◽  
Absolute Abundance ◽  
Density Estimates ◽  
Abundance Estimates ◽  
Short Period ◽  
Land Station

Single platform aerial line transect and land-based surveys of Southern Hemisphere Group IV humpback whales were undertaken to provide absoluteabundance estimates of animals migrating northward along the western Australian coast during June–August 2005. The aerial survey was designedto cover the whole period of northward migration but the resulting estimates from that survey alone could only, at best, provide relative abundanceestimates as it was not possible to estimate g(0), the detection probability along the trackline, from the data. Owing to logistical constraints, theland-based survey was only possible for a much shorter period (two weeks during the expected peak of the migration in mid-July). This paperproposes three methods that utilise these complementary data in different ways to attempt to obtain absolute abundance estimates. The aerial linetransect data were used to estimate relative whale density (for each day), allowing absolute abundance from the land-based survey to be estimatedfor the short period of its duration. In turn, the land-based survey allowed estimation of g(0) for the aerial survey. Absolute estimates of abundancefor the aerial survey were obtained by combining the g(0) estimate with the relative density estimates, summing over the appropriate number ofdays. The most reliable estimate of northward migrating whales passing the land station for the period of the land-based survey only was 4,700(95% CI 2,700–14,000). The most reliable estimate for the number of whales passing through the aerial survey region for the duration of that survey(55 days from June through to August) was 10,300 (95% CI 6,700–24,500). This is a conservative estimate because the duration of the aerial surveywas almost certainly shorter than the period of the migration. Extrapolation beyond the end of this survey was considered unreliable, but abundancefrom the estimated start of the migration to the end of the survey (87 days from mid-April to August) was estimated to be 12,800 (95% CI 7,500–44,600). The estimated number of whales depends crucially on the assumed migration and period of migration. Results for different migrationparameters are also presented. The point estimates of abundance, whilst higher than those from a previous survey in 1999 (when adjusted for surveyduration) are not significantly so. The peak of the whales’ distribution was found at c.90m water depth.

scholarly journals Short-term climate-induced change in French plant communities

2019 ◽  
Vol 15 (7) ◽  
pp. 20190280 ◽  
Author(s):  
Gabrielle Martin ◽  
Vincent Devictor ◽  
Eric Motard ◽  
Nathalie Machon ◽  
Emmanuelle Porcher
Keyword(s):  
Climate Change ◽  
Community Composition ◽  
Plant Community ◽  
Plant Communities ◽  
Thermal Preference ◽  
Plant Community Composition ◽  
Large Area ◽  
High Dispersal ◽  
Short Period ◽  
The Impact

Latitudinal and altitudinal range shifts in response to climate change have been reported for numerous animal species, especially those with high dispersal capacities. In plants, the impact of climate change on species distribution or community composition has been documented mainly over long periods (decades) and in specific habitats, often forests. Here, we broaden the results of such long-term, focused studies by examining climate-driven changes in plant community composition over a large area (France) encompassing multiple habitat types and over a short period (2009–2017). To this end, we measured mean community thermal preference, calculated as the community-weighted mean of the Ellenberg temperature indicator value, using data from a standardized participatory monitoring scheme. We report a rapid increase in the mean thermal preference of plant communities at national and regional scales, which we relate to climate change. This reshuffling of plant community composition corresponds to a relative increase in the abundance of warm- versus cold-adapted species. However, support for this trend was weaker when considering only the common species, including common annuals. Our results thus suggest for the first time that the response of plant communities to climate change involves subtle changes affecting all species rare and common, which can nonetheless be detected over short time periods. Whether such changes are sufficient to cope with the current climate warming remains to be ascertained.

Application of a Modified Vacuum Preloading Method on a Dredged Fill Soft Foundation

2012 ◽  
Vol 170-173 ◽  
pp. 3130-3134 ◽  
Author(s):  
Yun Liang Cui ◽  
Ming Jun Gao ◽  
Zhi Hao Liu
Keyword(s):  
Bearing Capacity ◽  
Reinforcement Effect ◽  
Large Area ◽  
Vacuum Preloading ◽  
Soft Foundation ◽  
Short Period ◽  
Dredging Sludge ◽  
Made In China ◽  
Preloading Method ◽  
Sand Cushion

A lot of large area lands were made in China coastal areas by dredging sludge from the sea. The dredged fill ground had a very low bearing capacity which should be increased as soon as possible to meet the requirements of constructions. However, conventional vacuum preloading could not be used for this purpose because the sand cushion could not be laid on the sludge ground due to the very low bearing capacity. To solve this problem, a modified vacuum preloading method without sand cushion was proposed. This method has been successfully tested and applied in the reclamation project in Wenzhou. Based on this project, the technological process and the key technology were introduced and the reinforcement effect was analyzed. Project results showed the modified vacuum preloading method could achieve a good reinforcement effect on large area dredged fill ground in a short period. It is worth to promote the application of this method in coastal reclamation projects.

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