Intestinal Microbial Ecology and Fillet Metal Chemistry of Wild Grey Mullets Reflect the Variability of the Aquatic Environment in a Western Mediterranean Coastal Lagoon (Santa Giusta, Sardinia, Italy)

Rosanna Floris,Francesco Sanna,Gabriele Sanna,Cecilia Teodora Satta,Carlo Piga,Nicola Fois,Antonella Lugliè

doi:10.3390/w13060879

Rosanna Floris, Francesco Sanna + Show 5 more

Open Access

https://doi.org/10.3390/w13060879

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Journal: Water	Publication Date: Mar 23, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: Sardegna Agricoltura, University of Sassari

Abstract

Fish populations play an active role in the maintenance of aquatic ecosystems biodiversity. Their intestinal microbiota and fillet chemistry depend on abiotic and biotic factors of the water environments that they inhabit. The present study investigated the grey mullets’ gut microbiota from a transitional aquatic ecosystem (Santa Giusta Lagoon, Sardinia, Italy) by a multidisciplinary approach which refers the results of (1) gut cultivable microbiota analyses (MA), (2) the trace metal assessment of fish muscle (TM), (3) the physico-chemical water monitoring (PC). MA detected the greatest number of total aerobic heterotrophic bacteria, Enterobacteriaceae and coliforms in Autumn (mean values 1.3 × 105, 2.4 × 104, 1.1 × 104 cfu g−1, respectively) when the accumulated rain and mean values of nutrients (reactive phosphorous and silica) were the highest. Marine bacteria were more numerous in Summer (mean value 7.4 × 105 cfu g−1) when the highest mean values of water temperature and salinity were registered. The gut bacteria were identified as Pseudomonas spp. (64%), Aeromonas spp. (17%), Ochrobactrum pseudogrignonense (10%), Providencia spp. (5%), Enterobacter ludwigii (2%) and Kocuria tytonicola (2%). TM showed that Ca, Na, B and Ni increased their concentrations in Winter while maxima of P, Zn, Cu and Fe were found in muscles of fish sampled in Summer. This study highlighted that the fish intestinal microbiota and metal composition of the fillet reflected the seasonal aquatic environmental variability.

Highlights

Transitional ecosystems such as marine lagoons represent a source of a wide and complex range of ecological goods and services, which are influenced by a range of physical, chemical and biological factors [1]
A multi-compartment and multi-disciplinary approach was carried out in order to investigate the microbial gut ecology and the metal contents of wild fish species from Santa Giusta Lagoon, a Mediterranean transitional ecosystem recognized as Site of Community Importance by the European Commission Habitat Directive
The bacteria quantified on the intestinal tract of the mullets reached values one or two orders of magnitude higher than what registered on the gut of gilthead seabreams from other Sardinian transitional ecosystems, in Winter, under the same laboratory growing conditions [12]

Summary

Introduction

Transitional ecosystems such as marine lagoons represent a source of a wide and complex range of ecological goods and services, which are influenced by a range of physical, chemical and biological factors [1]. Fish fauna constitute important indicators of anthropogenic stress, ecosystem recovery and resilience [6,7] because of their various form, diet, behavior, ability to migrate and the capacity to bio-accumulate toxic substances (metals, bacteria and other pollutants) in their edible parts and organs [8,9]. In this regard, fish intestinal microbiota plays a crucial role, being the reflection of the aquatic surroundings and favoring the adaptability of species to new environments [10]. Gut microbiota was explored both on reared and wild fish from all over the world [11], including coastal Mediterranean aquatic ecosystems [12,13]

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