scholarly journals Ecological studies of marine mammals using a seabed-mounted echosounder

2009 ◽  
Vol 66 (6) ◽  
pp. 1029-1036 ◽  
Author(s):  
Lise Doksæter ◽  
Olav R. Godø ◽  
Erik Olsen ◽  
Leif Nøttestad ◽  
Ruben Patel
Keyword(s):  
Marine Mammals ◽  
Principal Component ◽  
Dive Depth ◽  
Trophic Levels ◽  
Target Strength ◽  
Spatial Proximity ◽  
Ecological Studies ◽  
Marine Life ◽  
Deep Scattering Layer ◽  
Temporal And Spatial

Abstract Doksæter, L., Godø, O. R., Olsen, E., Nøttestad, L., and Patel, R. 2009. Ecological studies of marine mammals using a seabed-mounted echosounder. – ICES Journal of Marine Science, 66: 1029–1036. A seabed-mounted, upward-looking, 38 kHz echosounder (Simrad EK60) was used to monitor cetaceans for 128 d between July 2004 and June 2005. The echosounder was placed at 52°N 30°W at a depth of 910 m, in a frontal area with continuous upwelling creating a hotspot of marine life at all trophic levels. Echo tracks were observed, apparently resulting from one or more animals in close temporal and spatial proximity. The 69 “acoustic detections” were examined with a principal component analysis (PCA) considering mean target strength (TS), group size, and maximum dive depth and duration. The PCA conservatively classified 45 of the acoustic detections as “cetaceans”. Their mean TS values varied between −5 and −36 dB, in agreement with earlier TS measurements of whales and dolphins. Several of the supposed cetaceans were apparently feeding in the “deep-scattering layer” when this ascended at night. This study demonstrates that cetacean behaviour, including swimming, feeding, and vocalizing, can be observed and monitored with stationary active-acoustic instrumentation.

scholarly journals Measuring Legacies of Collective Racial Violence

2021 ◽  
Vol 694 (1) ◽  
pp. 122-139
Author(s):  
Sarah Gaby
Keyword(s):  
Racial Violence ◽  
Spatial Proximity ◽  
Empirical Inquiry ◽  
Legacy Effect ◽  
Housing Segregation ◽  
Temporal And Spatial ◽  
Racialized Violence ◽  
The Relationship

The “legacy effect” of lynchings and other forms of racialized violence has shaped patterns of inequality in America. While past studies have been relatively similar in their design—relating basic counts of lynchings to various contemporary outcomes—I argue for and demonstrate a more nuanced approach. I show that if we think of racialized violence as more than just the act of lynching, and consider both the temporal and spatial proximity between historic events of racial violence and contemporary inequality, we can establish this relationship in a more fulsome way. In the case of this study, the relationship is drawn to housing segregation. I argue that expanding the conceptualization of racial violence is critical for both empirical inquiry and shaping community efforts around redress.

scholarly journals Temporal and spatial variation of Myriapoda (Diplopoda and Chilopoda) assemblages in a Neotropical floodplain

2018 ◽  
Vol 18 (2) ◽  
Author(s):  
Lorhaine Santos-Silva ◽  
Tamaris Gimenez Pinheiro ◽  
Amazonas Chagas-Jr ◽  
Marinêz Isaac Marques ◽  
Leandro Dênis Battirola
Keyword(s):  
Spatial Variation ◽  
Habitat Type ◽  
Temporal Distribution ◽  
High Water ◽  
Trophic Levels ◽  
Temporal And Spatial Variation ◽  
Ecosystem Integrity ◽  
Mato Grosso ◽  
Temporal And Spatial ◽  
Hydrological Cycles

Abstract: Myriapods constitute important edaphic macrofauna taxa which dwell in different trophic levels and influence the dynamics of these environments. This study evaluated the variation in composition, richness and abundance of edaphic myriapod assemblages as a function of the distribution and structure of flooded and non-flooded habitats (spatial variation) and hydrological seasonality (temporal variation) in a floodplain of the northern Pantanal region of Mato Grosso, Brazil. Sampling was carried out in three areas of the Poconé Pantanal, along an altitudinal and inundation gradient consisting of inundated and non-inundated habitats and different vegetation formations. Three quadrats (10 x 10 m) were delimited within each habitat type, where sampling was performed using pitfall traps and mini-Winkler extractors during the dry, rising water, high water and receding water periods of two hydrological cycles within the Pantanal (2010/2011 and 2011/2012). A total of 549 millipedes were collected, consisting of 407 Diplopoda and 142 Chilopoda distributed in six orders, 12 families and 20 species. The assemblages composition varied throughout the seasonal periods, indicating that the rising water and dry periods differed from the high water and receding water periods. In addition to the variation between seasonal periods, myriapod richness and abundance also varied in relation to areas consisting of different vegetation formations. Thus, it can be concluded that the hydrological seasonality associated with the inundation gradient and different vegetation types were determinant in the heterogeneous spatial and temporal distribution of myriapod assemblages, validating that the conservation of these invertebrates in the Pantanal is directly linked to the preservation of vegetation, and consequently, ecosystem integrity.

scholarly journals Influence of Stratospheric Sudden Warming on AIRS Midtropospheric CO2

2013 ◽  
Vol 70 (8) ◽  
pp. 2566-2573 ◽  
Author(s):  
Xun Jiang ◽  
Jingqian Wang ◽  
Edward T. Olsen ◽  
Thomas Pagano ◽  
Luke L. Chen ◽  
...  
Keyword(s):  
Large Scale ◽  
Principal Component ◽  
Department Of Energy ◽  
Atmospheric Infrared Sounder ◽  
Stratospheric Sudden Warming ◽  
Chemical Tracers ◽  
Before And After ◽  
Temporal And Spatial ◽  
Global Reanalysis ◽  
Height Data

Abstract Midtropospheric CO2 retrievals from the Atmospheric Infrared Sounder (AIRS) were used to explore the influence of stratospheric sudden warming (SSW) on CO2 in the middle to upper troposphere. To choose the SSW events that had strong coupling between the stratosphere and troposphere, the authors applied a principal component analysis to the NCEP/Department of Energy Global Reanalysis 2 (NCEP-2) geopotential height data at 17 pressure levels. Two events (April 2003 and March 2005) that have strong couplings between the stratosphere and troposphere were chosen to investigate the influence of SSW on AIRS midtropospheric CO2. The authors investigated the temporal and spatial variations of AIRS midtropospheric CO2 before and after the SSW events and found that the midtropospheric CO2 concentrations increased by 2–3 ppm within a few days after the SSW events. These results can be used to better understand how the chemical tracers respond to the large-scale dynamics in the high latitudes.

On the quantification of habitability: merging the astrobiological and ecological schools

2018 ◽  
Vol 18 (05) ◽  
pp. 412-415
Author(s):  
Lien Rodríguez-López ◽  
Rolando Cardenas ◽  
Oscar Parra ◽  
Lisdelys González-Rodríguez ◽  
Osmel Martin ◽  
...  
Keyword(s):  
Ecological Models ◽  
Trophic Levels ◽  
Ecological Studies ◽  
Temporal Scales ◽  
Central Chile ◽  
Spatial And Temporal Scales ◽  
South Central

AbstractIn this paper, we connect ideas of the astrobiological and ecological schools to quantify habitability. We show how habitability indexes, devised using the astrobiologically inspired Quantitative Habitability Theory (QHT), can be embedded into ecological models of trophic levels. In particular, we address the problem of spatial-temporal scales. It turns out that the versatility of QHT allows to treat spatial and temporal scales typical of ecological studies. As a habitability index, we propose a new version of our Aquatic Primary Habitability, devised by some of us and formerly applied to saltwater ecosystems (both ocean and coastal) and now applied to freshwater. Although the aim of the paper is to outline the methodology rather than realism, initial steps for parameterization are considered for lakes of South-Central Chile.

Prey consumption estimates for salmon sharks

2019 ◽  
Vol 70 (6) ◽  
pp. 824 ◽  
Author(s):  
Kaitlyn A. Manishin ◽  
Kenneth J. Goldman ◽  
Margaret Short ◽  
Curry J. Cunningham ◽  
Peter A. H. Westley ◽  
...  
Keyword(s):  
Life History ◽  
Mass Balance ◽  
Marine Mammals ◽  
Extreme Values ◽  
Assimilation Efficiency ◽  
Prey Consumption ◽  
Trophic Levels ◽  
Shark Species ◽  
Top Predators ◽  
Balance Technique

Top predators, such as salmon sharks (Lamna ditropis), can influence the abundance and population structure of organisms at lower trophic levels through direct effects, such as predation mortality, and indirect interactions. As a first step towards better understanding the average annual prey consumption for individual adult salmon sharks, we bracketed consumption estimates using three methods: (1) daily ration requirement; (2) bioenergetic mass balance; and (3) a Bayesian model of shark growth. In the first method, we applied ration estimates for related lamnid shark species that yielded salmon shark estimates of 1461 and 2202kgyear–1. The second method used a mass–balance technique to incorporate life history information from salmon sharks and physiological parameters from other species and produced estimates of 1870, 2070, 1610 and 1762kgyear–1, depending on assumed diet. Growth modelling used salmon shark growth histories and yielded estimates of 16900 or 20800kgyear–1, depending on assumed assimilation efficiency. Of the consumption estimates, those from the mass–balance technique may be the most realistic because they incorporated salmon shark life history data and do not produce extreme values. Taken as a whole, these estimates suggest that salmon sharks have similar energetic requirements to piscivorous marine mammals.

scholarly journals Examining predator–prey body size, trophic level and body mass across marine and terrestrial mammals

2014 ◽  
Vol 281 (1797) ◽  
pp. 20142103 ◽  
Author(s):  
Marlee A. Tucker ◽  
Tracey L. Rogers
Keyword(s):  
Community Structure ◽  
Body Size ◽  
Body Mass ◽  
Marine Environment ◽  
Trophic Level ◽  
Marine Mammals ◽  
Trophic Position ◽  
Trophic Levels ◽  
Predator Prey ◽  
Terrestrial Mammals

Predator–prey relationships and trophic levels are indicators of community structure, and are important for monitoring ecosystem changes. Mammals colonized the marine environment on seven separate occasions, which resulted in differences in species' physiology, morphology and behaviour. It is likely that these changes have had a major effect upon predator–prey relationships and trophic position; however, the effect of environment is yet to be clarified. We compiled a dataset, based on the literature, to explore the relationship between body mass, trophic level and predator–prey ratio across terrestrial ( n = 51) and marine ( n = 56) mammals. We did not find the expected positive relationship between trophic level and body mass, but we did find that marine carnivores sit 1.3 trophic levels higher than terrestrial carnivores. Also, marine mammals are largely carnivorous and have significantly larger predator–prey ratios compared with their terrestrial counterparts. We propose that primary productivity, and its availability, is important for mammalian trophic structure and body size. Also, energy flow and community structure in the marine environment are influenced by differences in energy efficiency and increased food web stability. Enhancing our knowledge of feeding ecology in mammals has the potential to provide insights into the structure and functioning of marine and terrestrial communities.

scholarly journals Organic Contaminants in Zooplankton of Italian Subalpine Lakes: Patterns of Distribution and Seasonal Variations

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1901 ◽  
Author(s):  
Simona Pascariello ◽  
Michela Mazzoni ◽  
Roberta Bettinetti ◽  
Marina Manca ◽  
Martina Patelli ◽  
...  
Keyword(s):  
Organic Contaminants ◽  
Principal Component ◽  
Trophic Levels ◽  
Mean Values ◽  
Lake Maggiore ◽  
Subalpine Lakes ◽  
Main Driver ◽  
Trophic Webs ◽  
Persistent Organic Contaminants ◽  
Composition Pattern

Zooplankton is a key node in many trophic webs, both for food that for persistent organic contaminants that can accumulate in biota. Zooplankton of different size was seasonally sampled for two years in three deep Italian subalpine lakes (Maggiore, Como, Iseo) with the aim of determining the concentrations of perfluoroalkyl substances (PFAS), DDT, and PCB, and assessing the seasonality impacts on contaminants concentrations. In general, Lake Maggiore showed the highest concentrations for each group of contaminants, with mean values of 7.6 ng g−1 ww for PFAS, 65.0 ng g−1 dw for DDT, and 65.5 ng g−1 dw for PCB. When considering the composition pattern, perfluorooctane sulfonate (PFOS) was detected in 96% of the samples and it was the predominant PFAS compound in all of the lakes. pp’ DDE was the most detected congener among DDTs and their metabolites, while for PCBs, the prevalent group was hexa-CB that constituted 35.4% of the total PCB contamination. A seasonal trend was highlighted for all contaminant groups with concentrations in colder months greater than in spring and summer; it was evident that the contaminant concentrations were more dependent from seasonality than from size, trophic levels, and taxa composition of zooplankton. Principal component analysis showed that one of the main driver for the accumulation of most of the studied contaminants is their lipophilicity, except for perfluorooctanoic acid (PFOA) and octachlorobiphenyl.

South American sea lions Otaria byronia as biological samplers of local cephalopod fauna in the Patagonian shelf marine ecosystem

2019 ◽  
Vol 99 (06) ◽  
pp. 1459-1463
Author(s):  
R. L. Bustos ◽  
G. A. Daneri ◽  
E. A. Varela ◽  
A. Harrington ◽  
A. V. Volpedo ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Marine Ecosystem ◽  
Isotopic Signature ◽  
Trophic Levels ◽  
Trophic Relationships ◽  
South American ◽  
Sea Lions ◽  
Patagonian Shelf ◽  
Important Prey ◽  
Top Predators

AbstractCephalopods are important prey in the diet of top predators, such as marine mammals and seabirds. However, detailed information on their trophic relationships in the Patagonian marine ecosystem is scarce, including those cephalopod species with commercial interest. The aims of this study were to evaluate the composition of the cephalopod component in the diet of Otaria byronia and determine the habitat use and trophic levels of their main cephalopod prey by measuring the stable isotopic signature of cephalopod beaks. Between May 2005 and February 2009, fresh faecal samples were collected from two sea lions rookeries in San Matias Gulf. Cephalopods occurred in 39.4% of the 1112 samples collected during the whole period of study. The dominant prey species was Octopus tehuelchus, which occurred in 45.8% of scats containing cephalopod remains, and represented 58.7% in terms of numerical abundance and 52.0% in mass of cephalopods consumed. The second species most consumed was the myopsid Doryteuthis gahi. The significant higher δ15N values of O. tehuelchus beaks in comparison with those of D. gahi showed that these two species have different trophic levels while occupying similar habitat (δ13C values) in neritic waters of the Patagonian shelf.

scholarly journals Diel changes in acoustic and catch estimates of krill biomass

2009 ◽  
Vol 66 (6) ◽  
pp. 1318-1325 ◽  
Author(s):  
Yvan Simard ◽  
Marc Sourisseau
Keyword(s):  
Spatial Scales ◽  
Target Strength ◽  
Night Time ◽  
Diel Changes ◽  
Strobe Light ◽  
Light Pulses ◽  
Diel Vertical Migrations ◽  
Temporal And Spatial ◽  
The Difference ◽  
Fixed Distribution

Abstract Simard, Y., and Sourisseau, M. 2009. Diel changes in acoustic and catch estimates of krill biomass. – ICES Journal of Marine Science, 66: 1318–1325. Krill-biomass estimates can be compromised by diel variabilities in acoustic backscatter and the catch efficiencies of various nets. This paper describes an effort to quantify these variabilities at fine temporal and spatial scales during a three-day experiment at a fixed location, using high-resolution, stratified Bioness samples and echo-integration, and assuming a fixed distribution of krill orientations. Night-time catches in the krill scattering layer (SL) were 15 times the acoustic estimates. The situation was reversed during daytime, when the acoustic estimates in the SL were 5 times larger than the catches. This collectively resulted in a ±10‐dB gradual diel cycle in the difference of vertically integrated biomass from both sampling methods. Use of a strobe light on the Bioness reduced avoidance of the net by krill and significantly increased (×10) daytime catches in the SL, but had no significant effect on night-time catches. The difference in volume-backscattering strength at 120 and 38 kHz (ΔSv120–38) in the densest parts of the SL agreed with predictions using a target-strength (TS) model and an assumed normal distribution of tilt (mean θ = 11°; s.d. = 4°). The ΔSv120–38 was smaller for lower densities and during night-time. It appears that the θ and, therefore, TS distributions of krill significantly change during their diel vertical migrations. At twilight and at night, when they are feeding and swimming vertically, they exhibit lower mean TS and ΔSv120–38 and react less to strong strobe-light pulses, in contrast to daytime. Diel patterns in TS and net avoidance should be taken into account in krill-biomass assessments that use round the clock acoustic-survey data and multi-frequency TS models for target classification.

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