Mysid Life History and Seasonal Variation in Predation Pressure on Zooplankton

1983 ◽  
Vol 40 (11) ◽  
pp. 1968-1974 ◽  
Author(s):  
Paul A. Murtaugh
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Feeding Rate ◽  
Size Structure ◽  
Seasonal Fluctuations ◽  
Predation Intensity ◽  
Lake Washington ◽  
History Of ◽  
Relative Vulnerability

The bivoltine life history of Neomysis mercedis in Lake Washington, Seattle, results in seasonal variation in population size structure that influences the amount and quality of predation suffered by its zooplankton prey. Population densities and size–frequency data for Neomysis are combined with information on the influence of body size on feeding rate and composition of the diet to predict relative predation intensity on five size classes of Daphnia over a 27-mo period. An imperfect relationship between mysid numbers and expected predation intensity and seasonal fluctuations in the relative vulnerability of different-sized prey are two consequences of the mysid's pattern of life history.

Influence of a reservoir with surface release on the life history of the mayfly Heterocloeon curiosum (McDunnough) (Ephemeroptera: Baetidae)

1981 ◽  
Vol 59 (2) ◽  
pp. 305-314 ◽  
Author(s):  
Boris C. Kondratieff ◽  
J. Reese Voshell Jr.
Keyword(s):  
Life History ◽  
Benthic Macroinvertebrates ◽  
Temperature Regime ◽  
Life Histories ◽  
Second Generation ◽  
Larval Instars ◽  
History Of ◽  
Lake Anna

The life history of Heterocloeon curiosum was compared in the impounded North Anna River (NAR) and the free-flowing South Anna River (SAR) in Virginia, U.S.A. The study site on the NAR was 32 km below Lake Anna, a surface-release reservoir. Heterocloeon curiosum was bivoltine in both rivers with two summer generations and probable overwintering in the egg stage. It passed through 10 larval instars (range 9–12) in both rivers. The density of larvae was twice as great in the SAR as the NAR. Factors which may have contributed to the lesser success of H. curiosum in the NAR included bottom scouring produced by sudden increases in discharge, absence of the macrophyte Podostemum, quality of available food, and alterations of the temperature regime. Of these four factors, temperature probably had the most significant effect. The emergence of the second generation was 1 month later in the NAR because the reservoir delayed the normal seasonal cooling of the river. The nonoptimal temperature regime appeared to significantly reduce the fecundity of H. curiosum in the NAR. Our data indicate that surface-release reservoirs may have subtle but significant effects on the life histories of benthic macroinvertebrates.

Imperial Business in Africa Part II. Interpretations

1976 ◽  
Vol 17 (2) ◽  
pp. 267-290 ◽  
Author(s):  
A. G. Hopkins
Keyword(s):  
Spatial Distribution ◽  
East Africa ◽  
Size Structure ◽  
Colonial Period ◽  
Business History ◽  
African History ◽  
Colonial History ◽  
History Of ◽  
And Performance

This article, which is in two parts, aims to establish expatriate business history as a necessary and important part of modern African history. Part I surveyed approximately fifty histories of European companies in West, Central and East Africa during the colonial period and drew attention to newly-discovered and little-known records. Part II begins by assessing the quality of the studies listed in Part I, and suggests ways in which the level of scholarship can be raised to meet standards set by professionally-written business history. The article then formulates and explores a number of propositions concerning the spatial distribution and changing size, structure, strategy and performance of expatriate business in Africa. It is argued that many of these propositions cut across established but inadequately supported views, and that the development of business history has wider implications for the study of the colonial history of Africa.

The Life History of the Cirratulid Worm, Cirriformia Tentaculata, on an Intertidal Mudflat

1964 ◽  
Vol 44 (1) ◽  
pp. 47-65 ◽  
Author(s):  
J. D. George
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Seasonal Variation ◽  
Annual Cycle ◽  
Seasonal Fluctuation ◽  
Mortality Data ◽  
Intertidal Mudflat ◽  
History Of ◽  
Causes Of Mortality ◽  
Sexually Mature

The seasonal fluctuation in numbers of C. tentaculata was investigated from December 1959 until February 1962. The lowest numbers were recorded in April followed by a rapid increase in numbers during May. The magnitude of the increase varied from year to year, as also did the number of peaks that occurred during the summer months.The worm was shown to have an extended breeding season from the end of March to September during which several spawning ‘bursts’ took place. Experiments suggest that some spawning may occur when the mudflat is inundated by the rising tide, although spawning was not observed in the field.The population of C. tentaculata exhibited an annual cycle of growth which was influenced by the seasonal variation in temperature. Laboratory observations suggest that a temperature of about 20° C is optimal for the growth of young worms. The growth rate (8 mm/year) is slow compared with that of other polychaetes.It is tentatively concluded from the field mortality data that between 10 and 16 % of animals survive to an age at which they are sexually mature; between 6 and 8 % of each generation reach an age of 15 months. Causes of mortality in the population are briefly discussed.

scholarly journals The biology and ecology of the jumbo squid Dosidicus gigas (Cephalopoda) in Chilean waters: a review

2016 ◽  
Vol 43 (3) ◽  
pp. 402-414
Author(s):  
Christian M. Ibáñez ◽  
Roger D. Sepúlveda ◽  
Patricio Ulloa ◽  
Friedemann Keyl ◽  
M. Cecilia Pardo-Gandarillas
Keyword(s):  
Life History ◽  
Pacific Ocean ◽  
Size Structure ◽  
Feeding Habits ◽  
Marine Ecosystem ◽  
Background Information ◽  
Dosidicus Gigas ◽  
Southeastern Pacific ◽  
Jumbo Squid ◽  
History Of

The jumbo squid Dosidicus gigas is the most abundant cephalopod species in the southeastern Pacific Ocean, which supports the biggest cephalopod fishery in the world. Due to its growing economic importance, the population growth and distributional expansion of this squid is being increasingly studied. Nevertheless, some basic features of the biology of D. gigas are still unknown or have been poorly investigated. In this review we summarize the known information regarding the biology and ecology of this species in the southeastern Pacific Ocean; we focus on the Chilean region in order to propose hypotheses and research lines for a better understanding the life history of this organism. Available data on the size structure, reproduction and genetics of D. gigas allows us to propose hypotheses related to the squid’s life history traits. Based on the current literature and publications of colleagues, we propose two hypotheses regarding the effect of spatial variation on the life history of D. gigas. Hypothesis 1: Squids mature at large sizes and spawn in oceanic waters with warm temperatures where paralarvae and juveniles develop. Immature squids migrate near shore to feed, grow and mature, and then return to the offshore sites to spawn. Hypothesis 2: Alternatively, juvenile D. gigas in the oceanic zone do not migrate to coastal waters and mature at small sizes compared to individuals living near the coast that mature at larger size and migrate to oceanic waters to spawn. We provide background information about the feeding behavior and parasitism of this species, suggesting that D. gigas is an important trophic link in the southeastern Pacific marine ecosystem. However, more studies on the feeding habits, reproduction and parasite load are needed not only to test hypotheses proposed in this study, but also to advance the overall knowledge of this species.

Status and Aspects of the Life History of the Bottlenose Dolphin, Tursiops truncatus, in Florida

1975 ◽  
Vol 32 (7) ◽  
pp. 1055-1058 ◽  
Author(s):  
Daniel K. Odell
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
National Park ◽  
Bottlenose Dolphins ◽  
Everglades National Park ◽  
History Of

Aerial censuses in waters of the Everglades National Park, Florida every 1–2 mo between September 1973 and August 1974 resulted in sightings of a minimum of five, a maximum of 79, bottlenose dolphins. Seasonal variation in numbers apparently occurs.

Seasonal variation in the biochemical composition of Mytilicola intestinalis

Parasitology ◽  
1969 ◽  
Vol 59 (4) ◽  
pp. 775-782 ◽  
Author(s):  
C. S. Williams
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Seasonal Changes ◽  
Biochemical Composition ◽  
Free Living ◽  
Protein Levels ◽  
Copepod Parasite ◽  
History Of ◽  
Research Assistantship ◽  
The University

The biochemical constitution of the copepod parasite Mytilicola intestinalis was determined and seasonal changes were detected which, in general, could be correlated with the life-history of the parasite.Biochemical constituents have been discussed in relation to those in other endoparasites and free-living crustaceans. It was concluded that carbohydrates and lipids both formed important stores of energy in M. intestinalis. Protein levels were reduced compared with those in free-living forms.This work forms part of a Ph.D. thesis in the University of London. It was completed during the tenure of a Research Assistantship at The Polytechnic, Regent Street, London W. 1.

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