Reproducción de la nécora Macropipus puber (L.) (Decapoda, Brachyura) en la Ría de Arousa (Galicia, NW España), y primeros datos sobre la dinámica de la población
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[1] Instituto Español de Oceanografía
Instituto Español de Oceanografía
Madrid, España
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- Localización: Boletín. Instituto Español de Oceanografía, ISSN 0074-0195, Vol. 2, Nº. 1, 1985, págs. 10-32
- Idioma: español
- Texto completo no disponible (Saber más ...)
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Resumen
M. puber attains maturity in the “pubertal molt” and males show a clear discontinuity in the pre-ecdysis width/post-ecdysis width relationship. It is possible to establish a maturity size of 57 mm carapace width (CW). Using the presence of spermatophores as maturity criteria, 50% of the individuals are mature at 56 mm CW. Females show the above mentioned discontinuity at a size around 53 mm CW: 50% reach maturity at approximately 50 mm CW using the presence of “sperm plugs”, sperm in the spermatheca, the ripeness of the gonad and the presence of eggs attached to the pleopods as maturity criteria.
Pairing occurs prior to the female molting after which copulation takes place, and the attendance by the male lasts after copulation. Pairing was found to occur from 1 to 9 days before copulation (average value 5 days) and between several hours to 2 days (or up to 3 days intermitently) after. The pair remains in the copulation position from 4(+) to 20 hours (average value 8 + hours); at this moment the “sperm plug” is formed, lasting while the female is in the first post-ecdysial stages. The size of the pairing male is the same or larger than the pairing female, referring to the width prior to ecdysis.
After impregnation the female gonads begin to develop, and it is at the spawning when the eggs are fertilized. After only one impregnation, the female is able to spawn more than once and can even molt between the spawnings.
The egg diameter ranges from 0.360 mm at the time of spawning (0.352 mm was the lowest value found) to 0.460 mm (0.477 mm was the highest value) at the time of hatching. The average period between spawning and hatching is 48 days at 12-13 ºC (varying from 40 to 55 days), and hatching lasts around 40 hours.
Males do not show any reproductive cycle and there is a large number of mature individuals during the whole year.
The female, on the other hand, has a very clear reproductive cycle. This can be seen in the variation of the percentage of females with eggs, as well as in the values of the gonosomic index (G.I.) and the different stages of gonad development in the successive samplings. This reproductive cycle is clearly related to the growth cycle.
The highest values of the percentage of ovigerous females were found in January and March when two peaks are distinguishable. The G.I. shows a similar variation. It can be concluded that these two peaks are due to the fact that 85% of the females can have two successive spawnings. This is related to the high G.I. values of the ovigerous females in January and the stages of maturity of the eggs.
Fecundity was calculated according to the number of eggs (N) females can carry. The values chance according to the size of the individuals shown in the exponential equation, N= 0.105 CW^3.446 The minimum number of eggs was 34 491 (female of 47 mm CW) and 448 786 was the maximum (individual of 89 mm CW).
