The role of urbanisation in affecting Mytilus galloprovincialis

Abstract

Urbanisation is considered as one of the most critical and widespread threats to coastal marine ecosystems. The aim of this study was to compare the density, percentage cover, thickness of clumps, condition index and size-frequency distribution of Mytilus galloprovincialis between urban and non-urban shores, at nested spatial scales, in the Northern Portuguese coast. M. galloprovincialis was selected as model because it is economically and ecologically relevant. Moreover, the relationship between mussel size and the other variables (i.e. density, percentage cover, thickness and condition index) were investigated. Mussels on urban shores showed a smaller density and a greater frequency of larger individuals. A significant negative correlation between mussel length with density and with thickness of clumps was also found. Our results seem to indicate that recruitment has declined on urban shores and, as a result, intraspecific competition is also smaller, leading to more resources being available for a fewer individuals which can reach larger sizes. As mussel beds support a great biodiversity of invertebrates and provide many ecosystem services, urbanisation may have indirect effects on communities associated with mussels. Understanding the vulnerability of mussel beds to urbanisation could inform management.

Spatial-temporal variability of Mytilus galloprovincialis Lamarck 1819 populations and their accumulated sediment in northern Portugal

“…Along the northern Portuguese coast, intertidal area varies from soft to hard bottoms but they mostly present a mixture of both substrates. Sampling was done during low tide in the mid tide level of the rocky shores, that typically is dominated by the species M. galloprovincialis ( Veiga et al, 2020 ). In the north of Portugal, the spring–summer and the autumn–winter seasons are characterized by strong differences in mean monthly precipitation, air and water temperature, hydrodynamic conditions, wave height and storm frequency ( Dias et al, 2002 ; Bertocci et al, 2012 ).…”

“…However, for mussels this practice, requires the exploitation of wild populations, involving the collection of young mussels’ larvae directly from the water or harvesting of small mussels (0.5–2 cm) from intertidal and subtidal beds ( Consellería de Pesca, Marisqueo y Acuicultura, 2000 ; Cáceres-Martínez & Figueras, 2007 ; Figueras, 2007 ). This practice affects not only mussel juveniles but also adult stocks because it slows down the recovery of mussels ( Harris et al, 2003 ), and thus it may influence the whole communities associated with mussels ( Veiga et al, 2020 ).…”

“…Among anthropogenic disturbances, coastal urbanisation is one of the most persistent and increasing threats due to an increase of ocean sprawl and high diversity of pollutants coming from industry and domestic products ( Todd et al, 2019 ). Coastal urbanisation has proved to have negative effects on the abundance and size structure of intertidal M. galloprovincialis ( Veiga et al, 2020 ). Other anthropogenic disturbances like harvesting or trampling have also proved to have negative effects on mussels populations ( Smith & Murray, 2005 ).…”

The Subhabitat Dependence of Biogeographic Pattern

“…The sampling device was a metallic frame with 100 square subdivisions delimited with monofilament line. Abundance may be measured with different metrics in ecology (Veiga et al, 2020). We quantified abundance as percent cover, a non-destructive approach normally employed for sessile intertidal species (Menge et al, 2003;Catalán et al, 2020) that is also adequate for clonal seaweeds that grow in dense stands, for which the identification of individuals (as opposed to ramets) is very difficult (Scrosati, 2005).…”

Public perception of ecosystem services provided by the Mediterranean mussel Mytilus galloprovincialis related to anthropogenic activities

“…However, harvesting results in alteration of the features and extension of mussel beds thus affecting negatively the numbers (species abundance) and variety (total number of species) of the associated biodiversity ( Veiga et al, 2019 ). Although less charismatic than corals or kelps as perceived by people, M. galloprovincialis is a species ecologically important and especially vulnerable not only to harvesting but to other anthropogenic pressures such as trampling, presence of non-indigenous species or coastline urbanization ( Beukema & Cadée, 1996 ; Smith & Murray, 2005 ; Robinson et al, 2007 ; Carranza et al, 2009 ; Veiga et al, 2020 ). In this context, it is mandatory to involve society and improving its awareness about environmental policies to change its behaviour.…”