Do different sympatric seagrasses support macrobenthic faunas of differing composition, abundance, biodiversity or patchiness?

Intertidal macrobenthic assemblages associated with monospecific areas of different sympatric though not syntopic seagrasses [Cymodocea, Halodule, Zostera and Halophila] were investigated in Moreton Bay across a continuous <0.12 ha seagrass area with minimal potentially-confounding environmental variables. Results indicated patterns of unchanging faunal metrics across seagrass types (abundance, richness, diversity, evenness, taxonomic distinctness, and patchiness) but variation in relative proportions of dominant taxa, particularly microgastropods (abundant in Zostera, insignificant in Cymodocea and Halodule). Although assemblage composition varied, faunal dissimilarities (except with Zostera) were very low and of similar magnitudes within and between different 'host' seagrasses. This suggests that such macroecological faunal characteristics are not consequent on the precise local ecosystem engineer but largely reflect those of a common pool of locally available species, so that the differences in animal abundance and biodiversity described in some studies relate not directly to features inherent in the different seagrasses, but to associated habitat variables.

Relationships between plastic litter and chemical pollutants on benthic biodiversity

Five Descriptors (D) of Marine Strategy Framework Directive (MSFD): marine litter (D10), non-indigenous species (D2) and organic and inorganic pollutants (D8), were estimated in a coastal area of GSA 16 (Augusta harbour, Central Mediterranean Sea) in order to study their effects on the biodiversity (D1) of the benthic community D6) and to improve data for the MSFD. Investigation of plastic debris had led to the identification of 38 fragments divided into four categories, among which microplastics resulted as the most abundant. Six non-indigenous species, belonging to Polychaeta (Kirkegaardia dorsobranchialis, Notomastus aberans, Pista unibranchia, Pseudonereis anomala, Branchiomma bairdi) and Mollusca (Brachidontes pharaonis) were found. Biodiversity and benthic indices suggested a generalised, slightly disturbed ecological status. Anthracene, Zinc and Chrome were the most abundant chemical compounds in analysed sediments. Significant correlations were found between the abundance of trace elements vs biotic indices and between plastic debris vs biodiversity and benthic indices. This study represents the first report about the abundance of plastic debris and its relationship to contaminants and infauna in Augusta harbour. Our results can provide useful information for national and international laws and directives.