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

Abstract

Mytilus galloprovincialis is an ecosystem engineer that provides habitat and generates environmental heterogeneity, increasing local biodiversity. Moreover, it is an economically important species representing 14% of the global production of marine bivalves. Natural drivers and the increase of anthropogenic pressures, such as sediment stress, influence its populations on rocky shores. The objective of this study was to explore the spatial-temporal patterns of different M. galloprovincialis attributes along the north of Portugal. For that purpose, six rocky shores were selected and sampled six times along the year 2019. The percentage of cover, density, spat density, condition index, clump thickness, size classes and clump sediment content were considered. Results showed the lack of seasonality in M. galloprovincialis along the north coast of Portugal. However, density, spat stage, clump thickness, condition index and size classes showed some variability among dates and shores. The percentage cover and sediment content only significantly differed among shores. Our results indicated an absence of seasonality for all the studied variables, probably because temperature was always within the optimum range for this species and the abundance of food supply in the study area independently of the season. The accumulated sediment on mussel clumps did not show any temporal variability with only significant differences among shores. The accumulated sediment was composed mainly by medium and coarse sand and it was correlated with mussel average size, condition index, but especially with the mussel clump thickness.

Differences in the Structure and Diversity of Invertebrate Assemblages Harbored by an Intertidal Ecosystem Engineer between Urban and Non-Urban Shores

“…Similarly, a reduction in the abundance of ecosystem engineers was also found in the same study area for native canopy macroalgae [51]. However, a recent study [12] about the spatial and temporal variability of M. galloprovincialis along the north Portuguese shore showed that differences in its abundance among shores was dependent on sampling dates. Therefore, the inconsistency between results of [32] and those of our study may be the result of different sampling dates and natural variability in the abundance of M. galloprovincialis on the studied area rather than the effect of urbanization.…”

“…The Mediterranean mussel Mytilus galloprovincialis Lamarck, 1819 is an intertidal filterfeeding bivalve, widely distributed on the Atlantic rocky shores of the Iberian Peninsula, 2 of 12 and is one of the most abundant species at intertidal Portuguese rocky shores [11,12]. Furthermore, this species also plays an important role in intertidal food chains [13] and offers valuable ecosystem services, such as food, coastal protection or elimination of pollutants [14][15][16].…”

Effects of habitat homogenisation on assemblages associated with mussel clumps

“…Many of them (e.g., canopy macroalgae, corals and mussels) are considered ecosystem engineers because they alter local environmental conditions maintaining useful habitat for other organisms, thus enhancing local biodiversity [e.g., 9–12]. The Mediterranean mussel Mytilus galloprovincialis Lamarck, 1819 is an important economic marine resource and very abundant along the south Atlantic European and Mediterranean coasts, where this species is native [ 13 , 14 ]. It is a gregarious species that attaches to hard substrates using byssal threads and establishes dense clumps or beds on exposed or moderately exposed temperate rocky shores, such as in the northwest portion of the Iberian Peninsula, where temperature and food supply are optimal for the species [ 14 ].…”

“…The Mediterranean mussel Mytilus galloprovincialis Lamarck, 1819 is an important economic marine resource and very abundant along the south Atlantic European and Mediterranean coasts, where this species is native [ 13 , 14 ]. It is a gregarious species that attaches to hard substrates using byssal threads and establishes dense clumps or beds on exposed or moderately exposed temperate rocky shores, such as in the northwest portion of the Iberian Peninsula, where temperature and food supply are optimal for the species [ 14 ]. In areas where mussel species are dominant, they can prevent the attachment of other sessile organisms by competing for primary substratum [ 9 , 12 ].…”

“…Although M . galloprovincialis reaches high abundances in this region [ 14 ], wild populations are severely exploited since most of the mussel seed used in farming is collected from natural populations [ 28 ]. In addition to harvesting, mussel beds also suffer the effects of other anthropogenic disturbances, such as acidification, pollution and urbanization [ 29 – 35 ] as well as being submitted to natural disturbances (e.g., predation, wave exposure) [ 36 , 37 ].…”