Life History Patterns, Demography, and Population Dynamics

Author(s):  
Enric Cortés
Author(s):  
Kim K Jones ◽  
Trevan J Cornwell ◽  
Daniel L. Bottom ◽  
Staci Stein ◽  
Steven Starcevich

We quantified the population dynamics and life history diversity of seven brood years of coho salmon using a life-cycle approach. Four life history patterns, composed of fry, fry–nomad, parr, and yearling migrants indicated the importance of connectivity and access to a full range of freshwater and estuarine rearing environments through the year. Survival of each life history type varied annually with the yearling migrants contributing an average of 70% to the spawners in all but one return year. Fifty eight percent of the spawners of the 2013 return year had an estuarine rearing strategy, primarily parr migrants that overwintered in the estuary. Fry migrants, thought to be surplus production, were consistently observed in the estuary and represented in the returning spawners. The annual contribution of alternative rearing strategies to the spawners may support the resilience and viability of the population. We recommend that life cycle models of coho salmon account for the contribution of estuary migrants to the productivity and persistence of coho salmon in support of management and restoration of populations.


1987 ◽  
Vol 65 (4) ◽  
pp. 997-1000 ◽  
Author(s):  
Eric P. Hoberg

The Tetrabothriidae represent the dominant group of cestodes, previously known only as adult parasites, in marine birds and mammals. Recognition of their unique plerocercoid larvae provides the first definitive evidence for life history patterns and phylogenetic relationships with other cestodes. Affinities of the Tetrabothriidae and Tetraphyllidea, cestodes of elasmobranchs, are indicated by larval morphology and ontogeny. However, patterns of sequential heterochrony in the ontogeny of the adult scolex of Tetrabothrius sp. appear to be unique among the Eucestoda. Tetrabothriids constitute a fauna that originated by host switching from elasmobranchs to homeotherms, via ecological associations, following invasion of marine communities by birds and mammals in the Tertiary.


Crustaceana ◽  
2021 ◽  
Vol 94 (4) ◽  
pp. 413-429
Author(s):  
Ye Ji Lee ◽  
Won Gyu Park

Abstract The population dynamics of Stenothoe valida Dana, 1852 were studied at Cheongsapo beach of Busan, Republic of Korea, from March 2019 to March 2020. Sampling was conducted once a month at low tide during spring tides. Specimens were grouped by the cephalic length at 0.025 mm intervals, and classified into four categories: females, ovigerous females, males and juveniles. The sex ratio, defined as females : total males + females, exceeded 0.5 during most of the study period. Brood size was significantly coupled with ovigerous female size. Two to four cohorts appeared at each study period. New cohorts occurred at almost every sampling except in the samples Jun-2, and Nov-2. Life span was estimated at 1-2 months. The juvenile ratio, the ratio of ovigerous females, and the recruitment rate estimated by FiSAT were commonly high in summer and winter. The life history of S. valida was not coupled with water temperature, but had a strong seasonal pattern.


2006 ◽  
Vol 58 (4) ◽  
pp. 562-566 ◽  
Author(s):  
C. Reigada ◽  
W.A.C. Godoy

The effect of larval density on the survival, fecundity and body size at two temperatures in experimental populations of C. megacephala was studied. No effect from simultaneous influence of density and temperature on life history characteristics of C. megacephala was found. Significant effects of density and temperature on survival, fecundity and body size were observed. The importance of these results for the population dynamics of C. megacephala is discussed.


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