Reproductive trade-off of the copepod Acartia tonsa in a hypersaline estuary of Southwestern Atlantic.Temporal variations in the morphology of eggs

BERASATEGUI A.; FERNÁNDEZ SEVERINI M.D.; MENÉNDEZ MC; BIANCALANA F; DUTTO MS; GUINDER V. A.; LÓPEZ ABBATE M. C.; CHAZARRETA, J.; HOFFMEYER M. S.

MARINE BIOLOGY RESEARCH

TAYLOR & FRANCIS AS

Lugar: Londres; Año: 2016

1745-1000

This studyinvestigates the seasonal variation of the production, morphology and hatching successof Acartia tonsa eggs taking into account the variations of female?s size,population abundance and environmental factors in a turbid and hypersaline estuary.Sampling were performed considering the favorable (18-23°C and 32-36 salinity)and unfavorable periods (5-7ºC; 32-38) for this species in the Bahía BlancaEstuary (BBE). Incubation of field females were performed in laboratorysimulating in situ condition and specimens from fixed samples were counted. Observationsof egg?s morphology were made by SEM. A positive relationship of egg productionwith increasing temperature and salinity was revealed. An inverse relationshipof the sizes of females and eggs with decreasing temperature was also detected.Acartia tonsa displayed a marked seasonality in its reproductive strategy whichenabled it to the maintenance in the water column allyear round in the BBE. Toensure high offspring during favorable period, this species invested its energyin the production of subitaneous eggs (12.95±2.38 eggs f-1d-124) with smoothappearance and high percentage of viable eggs. Otherwise, during unfavorableperiod, A. tonsa invests energy in body mass as well as in the production ofthree egg morphotypes (6.56±3.2 eggs f-1d26 -1) whichrespond to a phenotypicevolution to ensure its survival. Despite of differences in the length andshape of the egg s ´ spines, these three types of eggs had the same delayedhatching behavior and the eggs with shorter spines would integrate the restingegg bank in the bottom sediments of the estuary.