Feeding dynamics of Terebralia palustris (Gastropoda: Potamididae) from a subtropical mangrove ecosystem

ABSTRACT

Mangrove gastropods are largely recognised for their roles as benthic deposit feeders that consume macrophyte-derived detritus. However, microalgae may also make a significant contribution towards the diet of these snails. Here we provide the first report on the rates at which microphytobenthos (MPB) is consumed by Terebralia palustris, an Indo-Pacific mangrove gastropod. Although juvenile T. palustris are generally detritivorous, there is increasing evidence that their occurrence on the seaward edge of the mangrove habitat allows them to incorporate a more nutritious food source to their diets in the form of microalgae. Using an experimental approach that incorporated fluorometric techniques, we found that the feeding activity of T. palustris on MPB was not clearly related to diel and tidal cycles at the subtropical location of Kosi Bay, South Africa during two sampling occasions in February and July 2015. However, a faster ingestion rate and higher consumption/digestion efficiency were recorded during experiments carried out in July. On this sampling occasion a higher percentage consumption of the available MPB was recorded, which corresponded to a lower per-capita availability in this resource. As T. palustris is able to consume MPB at variable rates, the impact of this species on benthic primary productivity within Indo-Pacific mangroves should not be overlooked when considering its integral ecological role within these threatened habitats.

KEYWORDS:

• Consumption/digestion efficiency
• estuarine lake
• feeding rate
• gut evacuation rate
• gut fluorescence technique
• microalgae
• South Africa

Acknowledgements

We thank the iSimangaliso Wetland Park Authority and Ezemvelo KZN Wildlife for supporting this research. Additional thanks go to Bradley Ah Yui, Schalk du Plooy and Christopher Nolte for their assistance with data collection. We are also grateful to the two anonymous reviewers as well as the Associate Editor for providing valuable input that strengthened the manuscript. The funders played no role in the study design, the decision to publish or the preparation of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Funding was provided by the National Research Foundation (NRF) of South Africa and the Nelson Mandela Metropolitan University. This work is based on the research supported by the South African Research Initiative of the Department of Science and Technology and the NRF.