Reproductive cycle and energetic cost of reproduction of the neogastropod Buccinum undatum in the Irish Sea

1993 ◽  
Vol 73 (2) ◽  
pp. 391-403 ◽  
Author(s):  
A. E. Kideys ◽  
R. D. M. Nash ◽  
R. G. Hartnoll
Keyword(s):  
Reproductive Cycle ◽  
Cost Of Reproduction ◽  
Egg Laying ◽  
Irish Sea ◽  
Energetic Cost ◽  
Ovary Development ◽  
Breeding Period ◽  
Laboratory Observation ◽  
Buccinum Undatum ◽  
The Irish Sea

The annual reproductive cycle and cost of reproduction of the common whelk, Buccinum undatum L. (Gastropoda: Prosobranchia) were studied off Douglas, south-east of the Isle of Man. Sexual maturity was reached at 60–70 mm shell length. Two years of laboratory observation and field data indicated an autumn to mid-winter breeding season. Egg-laying occurred in the laboratory mainly between December and January, and hatching of juveniles between April and early May, 3–5 months after spawning. The cycles of testis and ovary development were very similar, especially during the breeding period. The annual energy invested in reproduction was estimated to be at least 4.1 kj m-2. The investment by females (3.84 kj m-2 y-1) was much greater than by males (0.26 kj m-2 y-1).

INCUBATION IN MALLARDS (ANAS PLATYRHYNCHOS): CHANGES IN PLASMA LEVELS OF PROLACTIN AND LUTEINIZING HORMONE

1980 ◽  
Vol 86 (2) ◽  
pp. 371-379 ◽  
Author(s):  
A. R. GOLDSMITH ◽  
D. M. WILLIAMS
Keyword(s):  
Luteinizing Hormone ◽  
Breeding Season ◽  
Reproductive Cycle ◽  
Plasma Levels ◽  
Fixed Time ◽  
Prolactin Secretion ◽  
Egg Laying ◽  
Breeding Period ◽  
Male And Female ◽  
Incubation Behaviour

The concentrations of prolactin and LH were measured in the plasma of male and female mallards (Anasplatyrhynchos) during the breeding season. The concentration of prolactin in the female birds was low before and during egg-laying, increased threefold (P < 0·001 ) during incubation and returned to basal levels immediately after the young were hatched. The drakes, which do not participate in incubation in this species, had fairly low prolactin levels throughout the breeding period; levels being slightly higher during the incubation phase than at other times but still much lower (P < 0·001) than in the incubating females. Concentrations of LH in the females were high during egg-laying but declined at the onset of incubation. In the drakes levels of LH remained high for much longer and did not appear to decline at a fixed time relative to the reproductive cycle of the female birds. These observations support the view that prolactin is associated with incubation in birds, though the data do not permit a conclusion as to whether an increase in prolactin secretion causes incubation behaviour or is stimulated by it.

scholarly journals The Occurrence and Breeding of Sagitta Elegans Verrill and Sagitta Setosa J. Müller in Parts of the Irish Sea

1941 ◽  
Vol 25 (1) ◽  
pp. 113-124 ◽  
Author(s):  
E. Lowe Pierce
Keyword(s):  
Irish Sea ◽  
Annual Number ◽  
Breeding Period ◽  
Spawning Period ◽  
Liverpool Bay ◽  
Isle Of Man ◽  
Three Stages ◽  
The Irish Sea ◽  
Reproductive Cycles ◽  
Breeding Seasons

An investigation has been made of the species of Sagitta present in parts of the Irish Sea, their relative occurrence, and the annual number of reproductive cycles of each species. Three stages of maturity as described by Russell (1932a) have been used. To determine the maturity the Sagitta were transferred to a solution of 75% alcohol and stained with borax carmine.S. elegans Verrill and S. setosa J. Müller were collected in Liverpool Bay and in Port Erin harbour, Isle of Man. The former species was predominant at Port Erin. The coasts of Liverpool Bay have been added to the permanent range of S. setosa.At Port Erin there appears to be but one chief spawning period for S. elegans which extends generally from January through May. Following May the young forms appear in numbers and gradually mature through December to repeat the annual cycle.There appear to be two main breeding seasons for S. setosa in the outer Mersey Channels. The first and most noticeable begins in April and extends into June. There is evidence for a second breeding period in August.Both species were found in the samples taken from Morecambe Bay and Anglesey. The stage of maturity of these agreed with the Sagitta caught at the same time at Port Erin and Liverpool.The total monthly catches of Sagitta from Port Erin and the outer Mersey Channels have been recorded.

Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser
Keyword(s):  
Predation Risk ◽  
Reproductive Cycle ◽  
Perceived Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Size Variation ◽  
Egg Laying ◽  
Offspring Size ◽  
Natural Predation ◽  
Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

The medieval cultures of the Irish sea and the North Sea: Manannan and his neighbors [Book Review]

2019 ◽  
Vol 15 ◽  
pp. 142-144
Author(s):  
John Kennedy
Keyword(s):  
North Sea ◽  
Irish Sea ◽  
The North ◽  
The North Sea ◽  
The Irish Sea

Review(s) of: The medieval cultures of the Irish sea and the North Sea: Manannan and his neighbors, by MacQuarrie, Charles W., and Nagy, Joseph Falaky Nagy (eds), (Amsterdam: Amsterdam University Press, 2019) hardcover, 212 pages, 1 map, 4 figures, RRP euro99; ISBN 9789462989399.

scholarly journals Morphological abnormality in thornback ray Raja clavata in the Irish Sea

2021 ◽  
Author(s):  
L. J. Clarke
Keyword(s):  
Irish Sea ◽  
Beam Trawl ◽  
Morphological Abnormality ◽  
Free Swimming ◽  
Pectoral Fins ◽  
North Wales ◽  
Head Section ◽  
Thornback Ray ◽  
Raja Clavata ◽  
The Irish Sea

AbstractA free-swimming thornback ray Raja clavata specimen demonstrating significant morphological abnormality is reported, captured by beam trawl in the Irish Sea off north Wales, UK. The anterior sections of both pectoral fins were separated from the head section for a length of approximately 140 mm extending from the rostrum tip to a point posterior of the spiracles, along with abnormal morphology of the gill slits. This phenomenon has been observed elsewhere but is the first documented example of this abnormality in the eastern Irish Sea, despite widespread targeting of the species across the region by commercial and recreational fishers. Possible causes and consequences of the observed abnormality are discussed.

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