Responses of the infaunal peracarid Monokalliapseudes schubarti (Tanaidacea: Kalliapseudidae) to a bottom trawling disturbance and seasonality in an estuary of southern Brazil

ABSTRACT

The tanaid Monokalliapseudes schubarti is one of the dominant macrobenthic species in the shallow mudflats of southern Brazil. This species plays an important role in local trophic webs as a primary consumer and as a prey. This work investigated (1) the temporal variations in the population densities and structure of M. schubarti in the Patos Lagoon Estuary and (2) the potential impacts of shrimp trawling on the population densities, population structure and vertical stratification of the species in shallow areas of the estuary. The species exhibited significant temporal variability in its total densities and population structure, with a reproductive period observed during late summer and autumn, following an increase in salinity within the estuary. There were significant differences in M. schubarti densities, which appeared to be associated with variations in sediment texture and salinity. No well-defined pattern of trawling impact was identified; however, after high-impact trawling, decreases in the abundance of males and juveniles in the sediment superficial layer were recorded, and ovigerous females disappeared from the sampled area with relatively higher percentages of medium sand. Changes in the densities of different morphological categories observed after trawling were likely due to mortality, resuspension or rapid movement deeper into their tubes.

SUBJECT EDITOR:

• Francesc Maynou

KEYWORDS:

• Macrobenthos
• tanaid
• population structure
• disturbance
• experimental fishery

Acknowledgements

The authors thank all the participants in the field trips, the undergraduate students for their help with the laboratory work, the Laboratório de Oceanografia Geológica (LOG/IO/FURG) for providing laboratory materials and equipment for sediment analysis, and Andres Sajo and Andres Martín for reviewing the manuscript. Additionally, we thank the electronic microscopy centre of the Universidade Federal de Rio Grande (CEME-SUL) for the photographs of M. schubarti.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Ileana Ortega http://orcid.org/0000-0002-6234-5720

Additional information

Funding

This work was supported by the Project REBYC LAc -II FAO (FAO- GCP/RLA/201/GFF and GEF Project ID 5304). This study is also part of the Brazilian Long Term Ecological Research (PELD) project financed by CNPq (403805/2012-0). Ileana Ortega was granted a scholarship from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).