Seasonal changes in population structure of the tropical deep-water kelpLaminaria abyssalis

2013 ◽  
Vol 62 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Bianca V. Marins ◽  
Gilberto M. Amado-Filho ◽  
Elisabete Barbarino ◽  
Guilherme H. Pereira-Filho ◽  
Leila L. Longo
Keyword(s):  
Population Structure ◽  
Deep Water ◽  
Seasonal Changes

scholarly journals Population structure and reproductive characteristics of the silky shark Carcharhinus falciformis (Müller & Henle, 1839) (Carcharhiniformes: Carcharhinidae) off the coast of Oaxaca, Mexico

2017 ◽  
Vol 44 (3) ◽  
pp. 513-524
Author(s):  
María del Carmen Alejo-Plata ◽  
Miguel Ángel Ahumada-Sempoal ◽  
José Luis Gómez-Márquez ◽  
Adrián González-Acosta
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Seasonal Changes ◽  
Sexual Maturity ◽  
Size Structure ◽  
Landing Sites ◽  
Silky Shark ◽  
Oceanic Species ◽  
Carcharhinus Falciformis ◽  
Gravid Females

Carcharhinus falciformis is an abundant oceanic species, which occurs in equatorial and tropical zones, with an important catch in the Atlantic and Pacific coasts of Mexico. Samples were taken from December 2000 to December 2007 in four landing sites of the artisanal fleet on the coast of Oaxaca. During the period of study 1236 specimens (602 females and 634 males) of C. falciformis were registered. Total length (TL) ranged from 49 to 217 cm for females (mean = 111.3 cm) and from 59 to 265 cm for males (mean = 111.7 cm). The sex ratio of females to males was 1:1 ( 2 0.05 = 0.78, P > 0.05). The present data suggest a size at first sexual maturity of about 184.8 cm TL for females and 178.5 cm TL for males. The catches were composed mainly of young. In the 52 gravid females examined, the average number of embryos per female was seven; with a range of 3-14 embryos. Mean TL of embryos ranged from 10 to 66 cm with evidence of seasonal changes in the size structure. Results obtained showed that C. falciformis gives birth most of the year, with the highest proportion of births during the rainy season (May to October).

scholarly journals Population structure and morphology of South African deep‐water parapagurid hermit crabs

2019 ◽  
Vol 101 (3) ◽  
pp. 227-241
Author(s):  
Amy G. Wright ◽  
Charles L. Griffiths ◽  
Thomas P. A. Botha
Keyword(s):  
Population Structure ◽  
South African ◽  
Deep Water ◽  
Hermit Crabs ◽  
Structure And Morphology

scholarly journals Temperate fish community variation over seasons in relation to large-scale geographic seascape variables

2018 ◽  
Vol 75 (10) ◽  
pp. 1723-1732 ◽  
Author(s):  
Diana Perry ◽  
Thomas A.B. Staveley ◽  
Linus Hammar ◽  
Alyssa Meyers ◽  
Regina Lindborg ◽  
...  
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Seasonal Changes ◽  
Fish Community ◽  
Large Scale ◽  
Spatial Scales ◽  
Wave Exposure ◽  
Fish Assemblage Structure ◽  
Swedish West Coast ◽  
Latitudinal Position

In shallow-water marine environments, ecosystem functioning is a complex interworking of fine-scale characteristics and region-wide factors, and the importance of these variables can vary on multiple temporal and spatial scales. This underwater video study targeted seasonal changes in the fish community of seagrass habitats along the Swedish west coast and the influence of offshore seascape variables (latitudinal position, wave exposure, open ocean, and deep water). Results showed that fish assemblage structure exhibited seasonal changes between summer and autumn and strong spatiotemporal variations in the importance of offshore factors affecting shallow-water fish communities. In summer, abundance from the Gobiidae family responded to wave exposure, whereas the Gadidae family and juvenile migrant habitat preference guild responded to latitudinal position and proximity to deep water. In autumn, deep water was related to abundance of Gadidae and juvenile migrants, whereas latitudinal position influenced Gasterosteidae. These findings underscore the importance of understanding the influence of offshore factors on facets of coastal fish assemblages to address large-scale geographic connectivity along nearshore–offshore gradients.

scholarly journals Seasonal changes in size, sex-ratio and body condition of the damselfishChromis chromisin the central Mediterranean Sea

2014 ◽  
Vol 94 (5) ◽  
pp. 1053-1061 ◽  
Author(s):  
Claudia Bracciali ◽  
Susanna Piovano ◽  
Gianluca Sarà ◽  
Cristina Giacoma
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Body Condition ◽  
Seasonal Changes ◽  
Marine Protected Area ◽  
Reproductive Period ◽  
Rocky Shores ◽  
Central Mediterranean ◽  
Monthly Basis ◽  
Spawning Period

Chromis chromisis one of the most abundant fish species on the Mediterranean rocky shores. Acting as a by-pass of nutrients from the pelagic to the rocky littoral system, it plays an important role as a resource provider and has a relevant function in the community assemblage.Chromis chromishas many of the characteristics required of an indicator species (e.g. it is easy to recognize in the field, small sized, widespread and abundant). In this study we focused on individual size, sex-ratio and body condition in a damselfish population occurring in a central Mediterranean marine protected area. Fishing trials on a monthly basis (April–November) allowed us to assess seasonal changes in population structure. Fish were measured and weighed and a subsample was aged and sexed. On average, males were larger than females. The allometric coefficient,b, for the whole population was 2.99; the maximum age recorded was 7.5 yr. Before reproduction sex-ratio was close to parity (M:F 1:0.78), while a larger proportion of females was captured during the reproductive period. In conclusion, our results show that the population dynamics ofC. chromisis influenced by both sex and size. Since males and females have different behavioural strategies, and since the length of the spawning period is shorter in the smaller than in the larger-sized individuals, this is reflected in temporal changes observed in the population structure.

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