Mangrove Architects: How can sedimentary structures maximize food capture of fiddler crab?

• Grant number: 22/02276-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2022
• End date: August 31, 2023
• Field of knowledge: Biological Sciences - Zoology - Animal Behavior
• Principal Investigator: Tânia Marcia Costa
• Grantee: Tainá Moreira Ferreira
• Host Institution: Instituto de Biociências (IB-CLP). Universidade Estadual Paulista (UNESP). Campus Experimental do Litoral Paulista. São Vicente , SP, Brazil
• Associated scholarship(s): 22/14395-6 - Pathways of carbon cycling in fiddler crab burrows and their sedimentary structures in mangroves, BE.EP.IC

Abstract

Construction of sedimentary structures can be observed in the most diverse animal groups. In addition to playing an important role in the survival and evolution of the animals that produce them, they can also influence ecological processes in ecosystems such as the biogeochemical cycling of nutrients and the hydrodynamics of the environment. Fiddler crabs are organisms that build sedimentary structures, which can vary in function according to species, sex, and life stage. The Fiddler crab Leptuca thayeri builds sedimentary structures in the form of chimneys at the entrance to the burrows. Chimneys are mainly constructed during the reproductive months and are larger in the burrows of females that are hatching their eggs (ovigerous females) than in the burrows of non-ovigerous females and adult males. Since the species can feed on phytoplankton, and considering that sedimentary structures can help in the formation of vorticity regions that slow down the flow of water, we hypothesized that chimneys could act as a phytoplankton trap during high tide. Greater efficiency of phytoplankton capture could be advantageous for females to supply their energy needs mainly during the incubation of eggs, a period in which their movements may be limited and their foraging efficiency reduced. In this context, to test whether the amount of phytoplankton captured in burrows varies according to chimney size, we will carry out a field experiment in which we will build burrow simulacra with chimneys of different heights (simulating chimneys built by ovigerous females, non-ovigerous females, and adult males) and we will compare the amount of phytoplankton captured after the high tide period. In a second experiment, to assess whether the incubation period imposes restrictions on the foraging of females, we will compare feeding-related behaviors, such as plucking in the sediment and the period outside the burrow in ovigerous females, non-ovigerous females, and adult males. Thus, we expect the chimneys to increase the phytoplankton capture rate favoring the feeding of ovigerous females during the incubation period. (AU)