Preliminary Insight into Winter Native Fish Assemblages in Guadiana Estuary Salt Marshes Coping with Environmental Variability and Non-Indigenous Fish Introduction

Abstract

This work aims to undertake a preliminary characterization of winter fish assemblages in the salt marsh areas of Guadiana lower estuary (South-East Portugal) and discusses the potential risks of habitat dominance by a non-indigenous species (NIS). To this effect, six field campaigns were carried out in four sampling sites during winter season targeting the collection of fish species. A total of 48 samples were collected. Individuals from seven different taxa (marine and estuarine) were collected, although the assemblage was dominated by two estuarine species-the native Pomatoschistus sp. (goby) and the NIS Fundulus heteroclitus (mummichog). Goby was the most abundant taxa in the majority of salt marsh habitats, except for one specific, marsh pool, where extreme environmental conditions were registered, namely high temperature and salinity. Such conditions may have boosted the intrusion of mummichog in this area. This species is well adapted to a wide range of abiotic factors enabling them to colonize habitats where no predators inhabit. Impacts of mummichog introduction in the Guadiana salt marsh area are still unpredictable since this is the first time they have been recorded in such high density. Nevertheless, in scenarios of increased anthropogenic pressure and, consequently, habitat degradation, there is a potential risk of mummichog spreading to other habitats and therefore competing for space and food resources with native species.

First record of Synidotea laticauda Benedict, 1897 (Crustacea: Isopoda) in the Guadiana Estuary (SW Iberian Peninsula)

“…Shipping traffic of medium and small vessels along the lower 50 km of the Guadiana Estuary, mainly for recreational use, and coming from all over the world, could have acted as vectors for the accidental introduction of this species. Some authors have also reported recent alien species invasions and establishment in this estuary and nearby salt marshes, and have pointed to shipping traffic and flow regulation as potential causes (Chícharo et al, 2009;Gonçalves et al, 2017).…”

Peer Review #1 of "Invasion genetics of the mummichog (Fundulus heteroclitus): recent anthropogenic introduction in Iberia (v0.1)"

“…In the Iberian Peninsula, F. heteroclitus was first detected in the 1970s, in the Guadalquivir and Guadiana saltmarshes (southwestern coast of Spain) (Hernando 1975) and in the Guadiana Delta (Coelho et al 1976). More recently, its presence was also reported in the Ebro Delta, northeastern coast of Spain (Gisbert & López 2007) and in the Ria Formosa, south of Portugal (e.g., Catry et al 2006) where it can reach high densities (Gonçalves et al 2017).The species was probably introduced between 1970 and 1973 in the Spanish saltmarshes (Fernández-Delgado 1989) either involuntarily via aquarium trade (e.g. Elvira & Almodóvar 2001), ballast water (Fernández-Delgado 2010; García-Revillo & Fernández-Delgado 2009), or intentionally for purposes of biological control (Gozlan 2010).…”

Invasion genetics of the mummichog (Fundulus heteroclitus): recent anthropogenic introduction in Iberia

“…In the Iberian Peninsula, F. heteroclitus was first detected in the 1970s, in the Guadalquivir and Guadiana saltmarshes (southwestern coast of Spain) (Hernando, 1975) and in the Guadiana Delta (Coelho, Gomes & Ré, 1976). More recently, its presence was also reported in the Ebro Delta, northeastern coast of Spain (Gisbert & López, 2007) and in the Ria Formosa lagoon, south of Portugal (e.g., Catry et al, 2006) where it can reach high densities (Gonçalves et al., 2017). The species was probably introduced between 1970 and 1973 in the Spanish saltmarshes (Fernández-Delgado, 1989) either involuntarily via aquarium trade (e.g., Elvira & Almodóvar, 2001), ballast water (Fernández-Delgado, 2010; García-Revillo & Fernández-Delgado, 2009), or intentionally for purposes of biological control (Gozlan, 2010).…”