Population structure, relative growth and morphological sexual maturity of the snapping shrimp Alpheus brasileiro Anker, 2012 (Caridea: Alpheidae) from the south-eastern coast of Brazil

ABSTRACT

The present study investigated the population structure of the snapping shrimp Alpheus brasileiro. We tested the hypotheses that the sex ratio of the population differs from the expected 1:1 and that the growth pattern differs between adults and juveniles and between sexes. Reproductive period, juvenile recruitment and morphological sexual maturity were estimated. Samples were collected in two periods. The first sampling occurred bimonthly from March 2013 to January 2014. The second sampling occurred monthly from April 2015 to March 2016. The population structure was determined based on the size-frequency distribution of different demographic categories. To analyse the relative growth, we measured the second pleuron length, major cheliped propodus length, major cheliped propodus width, major cheliped propodus height, appendix interna length, appendix masculina length. The results showed that the sex ratio did not differ from 1:1 (male:female). Reproduction and juvenile recruitment were continuous throughout the study period. The analysis of relative growth confirmed the hypothesis that males and females, and juveniles and adults, have different growth patterns, indicating distinct strategies of energy allocation. The estimated carapace length at the onset of morphological sexual maturity was 4.9 mm in males and 4.7 mm in females. The results obtained in this study are probably related to the monogamous social behaviour of A. brasileiro. Monogamy can influence demographic parameters such as sex ratio and the size at which males and females reach morphological sexual maturity.

SUBJECT EDITOR:

• Audrey J. Geffen

KEYWORDS:

• Population structure
• sex ratio
• allometry
• energy allocation
• sexual maturity

Acknowledgements

We thank the LABCAM co-workers for their help during the fieldwork, and João Alberto Farinelli Pantaleão for illustration of body dimensions.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Régis Augusto Pescinelli http://orcid.org/0000-0003-4109-3859

Alexandre Oliveira Almeida http://orcid.org/0000-0003-0470-8658

Rogério Caetano Costa http://orcid.org/0000-0002-1342-7340

Additional information

Funding

This research was financed by the São Paulo Research Foundation – FAPESP (Scholarship Grant No. 2013/12136-4 to RAP; Thematic Biota Grant No. 2010/50188-8 to RCC), to the National Council for Scientific and Technological Development – CNPq (Research Scholarships No. 305919/2014-8 to RCC, 305939/2015-7 to AOA and 140608/2015-0 to RAP).