Diel Pelagic Foraging by a Pandalid Shrimp (Pandalus montagui) off Resolution Island (Eastern Hudson Strait)

1992 ◽  
Vol 49 (3) ◽  
pp. 565-576 ◽  
Author(s):  
C. Hudon ◽  
D. G. Parsons ◽  
R. Crawford
Keyword(s):  
Sex Ratio ◽  
Vertical Distribution ◽  
Feeding Activity ◽  
Bottom Trawl ◽  
Staple Food ◽  
Benthic Organisms ◽  
Size Frequency Distribution ◽  
Ratio Size ◽  
Plankton Sampler ◽  
The Vertical Distribution

The vertical distribution and diet of shrimp (Pandalus montagui) were investigated using a multistage plankton sampler (BIONESS) and were compared with those of shrimp captured on the bottom using a trawl. Massive nocturnal vertical migrations of shrimp were observed in association with intense pelagic feeding activity. The sex ratio, size frequency distribution, and diet of shrimp caught in the water column differed markedly from shrimp caught during their stay on the bottom. Pelagic migrants were mostly males (75%), extending their planktonic foray into morning hours, whereas ovigerous (12%) and nonovigerous (13%) females returned to the bottom at dawn. In the trawl, the representation of males (43%) and ovigerous females (45%) differed, but also fluctuated on a diel cycle. Stomachs of shrimp captured in the BIONESS were fuller and the contents were in better condition than found in shrimps captured in the bottom trawl. Pelagic shrimp fed opportunistically on a variety of zooplankters, using copepods as a staple food. Stomachs of shrimp from the bottom trawl contained chitinous debris, sand grains, and small amounts of benthic organisms. The occurrence of daily vertical feeding migrations results in the unavailability of a variable proportion of the total shrimp biomass to bottom trawls.

scholarly journals Population attributes of Littoraria angulifera (Gastropoda: Littorinidae) in mangroves in Bahia State, northeastern Brazil

2022 ◽  
Vol 82 ◽  
Author(s):  
G. Boehs ◽  
L. A. de Freitas
Keyword(s):  
Sex Ratio ◽  
Vertical Distribution ◽  
Spartina Alterniflora ◽  
Time Distribution ◽  
Northeastern Brazil ◽  
Mangrove Tree ◽  
Red Mangrove ◽  
Continuous Reproduction ◽  
Average Size ◽  
The Vertical Distribution

Abstract Littoraria angulifera (Lamarck, 1822) is an estuarine gastropod of tropical occurrence, which lives mainly on trunks of mangrove tree species. This study aimed to evaluate the population attributes of this species, such as abundance, space-time distribution, sex ratio and recruitment in mangroves in Bahia State, northeastern Brazil. The specimens were collected monthly throughout 2018, on trunks of the red mangrove Rhizophora mangle L. at two heights and on two horizontal levels. Specimens that were on the marine grass Spartina alterniflora Loisel were also collected. After counting, biometrics and sexing, the specimens were returned alive to the environment. The average size and weight of L. angulifera was higher (p<0.05) in places with taller and less sparse trees and the vertical distribution on the trunks showed a preference for strata close to the soil. Both results are related to shading and protection against desiccation. Females were more abundant than males, at an approximate sex ratio F: M of 1.4: 1. Recruits were observed throughout the period, showing continuous reproduction of the species with a recruitment peak in spring (September to November). The study revealed the importance of keep the mangroves intact to allow the maintenance of the natural stocks of the species.

An Acoustic Study of Shrimp (Pandalus montagui) Distribution near Resolution Island (Eastern Hudson Strait)

1992 ◽  
Vol 49 (5) ◽  
pp. 842-856 ◽  
Author(s):  
R. E. Crawford ◽  
C. Hudon ◽  
D. G. Parsons
Keyword(s):  
Vertical Distribution ◽  
Vertical Migration ◽  
Horizontal Distribution ◽  
Bottom Trawl ◽  
Diel Migration ◽  
Acoustic Study ◽  
Downward Migration ◽  
Plankton Sampler ◽  
Horizontal And Vertical Distribution

Echo integration, a multistage plankton sampler (BIONESS), and a bottom trawl were used to examine the horizontal and vertical distribution of shrimp (Pandalus montagui) near Resolution Island in eastern Hudson Strait. Shrimp were concentrated in two locations within the study area and they maintained this pattern of horizontal distribution for at least 7 d. Acoustic observations revealed a scale of horizontal patchiness that was obscured by the "homogenization effect" of sampling by bottom trawl and plankton net. The shrimp underwent a nocturnal vertical migration with other zooplankton to > 200 m from the bottom and a subsequent downward migration during early daylight hours. This diel migration resulted in reduced availability of shrimp to the bottom trawl at night. Timing of the migrations varied, possibly as a result of interaction with oceanographic processes.

The vertical distribution of thin features over the Arctic analysed from CALIPSO observations. Part I: Optically thin clouds

Tellus B ◽  
2011 ◽  
Vol 63 (1) ◽  
Author(s):  
Abhay Devasthale ◽  
Michael Tjernström ◽  
Karl-Göran Karlsson ◽  
Manu Anna Thomas ◽  
Colin Jones ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
The Arctic ◽  
The Vertical Distribution

scholarly journals Continuous borehole optical televiewing reveals variable englacial debris concentrations at Khumbu Glacier, Nepal

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Katie E. Miles ◽  
Bryn Hubbard ◽  
Evan S. Miles ◽  
Duncan J. Quincey ◽  
Ann V. Rowan ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Water Supply ◽  
Depth Profile ◽  
Variable Thickness ◽  
Surface Melting ◽  
High Mountain ◽  
Ablation Area ◽  
The Mean ◽  
Surface Melt ◽  
The Vertical Distribution

AbstractSurface melting of High Mountain Asian debris-covered glaciers shapes the seasonal water supply to millions of people. This melt is strongly influenced by the spatially variable thickness of the supraglacial debris layer, which is itself partially controlled by englacial debris concentration and melt-out. Here, we present measurements of deep englacial debris concentrations from debris-covered Khumbu Glacier, Nepal, based on four borehole optical televiewer logs, each up to 150 m long. The mean borehole englacial debris content is ≤ 0.7% by volume in the glacier’s mid-to-upper ablation area, and increases to 6.4% by volume near the terminus. These concentrations are higher than those reported for other valley glaciers, although those measurements relate to discrete samples while our approach yields a continuous depth profile. The vertical distribution of englacial debris increases with depth, but is also highly variable, which will complicate predictions of future rates of surface melt and debris exhumation at such glaciers.

A case study on the vertical distribution and characteristics of aerosols using ground-based raman lidar, satellite and model over Western India

2021 ◽  
Vol 42 (17) ◽  
pp. 6421-6436
Author(s):  
Sourita Saha ◽  
Som Sharma ◽  
K. Niranjan Kumar ◽  
Prashant Kumar ◽  
Vaidehi Joshi ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Western India ◽  
Raman Lidar ◽  
The Vertical Distribution
Sign in / Sign up

Export Citation Format

Share Document