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

Abstract

Nowadays, coastal urbanization is one of the most serious and prevalent pressures on marine ecosystems, impacting their biodiversity. The objective of this study was to explore differences in attributes and biodiversity associated with an intertidal ecosystem engineer, the mussel Mytilus galloprovincialis Lamarck, 1819 between urban and non-urban shores. For this, mussel attributes and their associated macrofauna were compared between urban and non-urban rocky shores in the north of Portugal. Results showed that the largest sized mussels were more frequent on urban shores, whereas the smallest size class was only present in non-urban shores. Regarding macrofauna associated with mussels, the number of taxa was significantly higher on non-urban shores. Moreover, the structure of the macrobenhic assemblages was significantly different between urban and non-urban shores. Most important taxa responsible for differences were more abundant on non-urban shores except for Nucella lapillus, Idotea pelagica and Oligochaeta that were more abundant on urban shores. Therefore, our results showed that the mussel size frequency and the structure of the associated macrobenthic assemblages changed in urban shores. Considering the relevance of mussel beds for biodiversity and human well-being, our results indicate the need of adopting proper management plans to minimize these effects on urban intertidal ecosystems.

Influence of Urbanization on Patterns of Variability of Mytilus galloprovincialis Populations

“…In this way, studies assessing the variability of populations can be useful to detect disturbance impacts since changes in patterns of variability can be detected even before responses in mean values were detected [43], as results of the present study showed. Moreover, previous studies conducted in the same area have also indicated a decreasing of mussel density, an increasing of shell length beside changes in abundance of native macroalga canopy and in macrofaunal assemblages associated with M. galloprovincialis beds in intertidal urban shores, in comparison to non-urban ones [6,38,62]. A recent study indicates that Mytilus populations are declining in North Atlantic waters by their extreme exploitation, linked to direct and indirect effects of climate change [63].…”

“…They attach to hard substrates through their byssal threads and establish dense clumps or beds that can be mono-or multilayered [3,4]. This species bears great ecological importance in coastal ecosystems, being considered an ecosystem-engineer [5,6]. On one hand, being an active filter-feeder organism, they play a relevant role as linkage in trophic chains between benthic organisms and phytoplankton [3,7] and improve water quality by removing pollutants, particles, excess nitrogen and other hazardous substances from the aquatic environment [3,4].…”

“…On one hand, being an active filter-feeder organism, they play a relevant role as linkage in trophic chains between benthic organisms and phytoplankton [3,7] and improve water quality by removing pollutants, particles, excess nitrogen and other hazardous substances from the aquatic environment [3,4]. On the other hand, mussel beds enhance habitat complexity and therefore biodiversity, by providing useful habitat and protection to many organisms and nurseries to juveniles [6,8]. Mytilus galloprovincialis is also an economically relevant marine resource, severely exploited in many European countries such as Italy, Spain and Portugal for human consumption [9].…”