Are "empty forests" of planarians occurring in the Atlantic Forest? An initial approach in Southeastern Brazil

• Grant number: 24/22450-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Biological Sciences - Ecology
• Principal Investigator: Marcos Ricardo Bornschein
• Grantee: Alexandre de Campos Fernandes
• Host Institution: Instituto de Biociências (IB-CLP). Universidade Estadual Paulista (UNESP). Campus Experimental do Litoral Paulista. São Vicente , SP, Brazil

Abstract

Terrestrial planarians are nocturnal, sensitive to environmental disturbances, and susceptible to desiccation due to variations in temperature and humidity, which is why they are used as bioindicators of soil and environmental quality. Little is known about this group in the Atlantic Forest, where we hypothesize that there may be areas lacking this mesofaunal group due to the environmental degradation of remaining forests. We aim to evaluate this hypothesis through sampling in the southeastern region of Brazil (state of São Paulo), both in Dense Ombrophilous Submontane Forest (continuous forest) and in stages of regeneration of this vegetation. We will collect leaf litter from 0.5 m x 0.5 m plots. Twenty plots will be allocated every 2 meters along a transect, and three transects will be set up per environment. We will sample four environments (control, forest regenerated after clear-cutting, and two stages of tree vegetation that have not yet regenerated to a forest condition), totaling 12 transects and 240 plots. We will also characterize the tree and herbaceous vegetation in two 10 m x 10 m plots per transect (24 plots) and the microclimate (temperature and humidity) for each environment using data loggers. The leaf litter will be exposed to light to capture the planarians escaping from the heat. The specimens will be fixed in 10% formalin and preserved in 70% alcohol. We will prepare histological slides of the gonadal and cephalic regions and stain them using conventional techniques for species identification by analyzing characteristics such as morphology of the testicles, efferent ducts, prostate vesicle, male atrium, penial papilla, ovaries, oviducts, and female atrium. The material will be deposited in the Ecology and Evolution Laboratory (USP-EACH). We will characterize and compare abiotic and biotic data of planarian and vegetation communities using conventional descriptors such as richness, abundance, frequency, diversity, and similarity/dissimilarity, which will be statistically evaluated using Generalized Linear Models (GLMs), comparing them with different regeneration gradients. We will assess which environmental characteristics most influence the terrestrial planarian communities through GLMs, comparing community metrics with ecological and environmental parameters. The absence of species in regenerated areas that are frequent in the control sites will indicate the condition of an empty forest, unless there are microclimatic differences between the sampled locations. This study will be one of the few on the Atlantic Forest biome involving planarians and the first with a conservationist approach.