SPONGE RESEARCH DEVELOPMENTS

Hydrobiologia

, Volume 687, Issue 1, pp 163-177

First online:

Role of deep sponge grounds in the Mediterranean Sea: a case study in southern Italy

  • Marzia BoAffiliated withDip. Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche Email author 
  • , Marco BertolinoAffiliated withDip. Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche
  • , Giorgio BavestrelloAffiliated withDip. Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche
  • , Simonepietro CaneseAffiliated withISPRA
  • , Michela GiustiAffiliated withISPRA
  • , Michela AngiolilloAffiliated withISPRA
  • , Maurizio PansiniAffiliated withDip. per lo Studio del Territorio e delle sue Risorse, Università degli Studi di Genova
  • , Marco TavianiAffiliated withISMAR-CNR

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

The Mediterranean spongofauna is relatively well-known for habitats shallower than 100 m, but, differently from oceanic basins, information upon diversity and functional role of sponge grounds inhabiting deep environments is much more fragmentary. Aims of this article are to characterize through ROV image analysis the population structure of the sponge assemblages found in two deep habitats of the Mediterranean Sea and to test their structuring role, mainly focusing on the demosponges Pachastrella monilifera Schmidt, 1868 and Poecillastra compressa (Bowerbank, 1866). In both study sites, the two target sponge species constitute a mixed assemblage. In the Amendolara Bank (Ionian Sea), where P. compressa is the most abundant species, sponges extend on a peculiar tabular bedrock between 120 and 180 m depth with an average total abundance of 7.3 ± 1.1 specimens m−2 (approximately 230 gWW m−2 of biomass). In contrast, the deeper assemblage of Bari Canyon (average total abundance 10.0 ± 0.7 specimens m−2, approximately 315 gWW m−2 of biomass), located in the southwestern Adriatic Sea between 380 and 500 m depth, is dominated by P. monilifera mixed with living colonies of the scleractinian Madrepora oculata Linnaeus, 1758, the latter showing a total biomass comparable to that of sponges (386 gWW m−2). Due to their erect growth habit, these sponges contribute to create complex three-dimensional habitats in otherwise homogenous environments exposed to high sedimentation rates and attract numerous species of mobile invertebrates (mainly echinoderms) and fish. Sponges themselves may represent a secondary substrate for a specialized associated fauna, such zoanthids. As demonstrated in oceanic environments sponge beds support also in the Mediterranean Sea locally rich biodiversity levels. Sponges emerge also as important elements of benthic–pelagic coupling in these deep habitats. In fact, while exploiting the suspended organic matter, about 20% of the Bari sponge assemblage is also severely affected by cidarid sea urchin grazing, responsible to cause visible damages to the sponge tissues (an average of 12.1 ± 1.8 gWW of individual biomass removed by grazing). Hence, in deep-sea ecosystems, not only the coral habitats, but also the grounds of massive sponges represent important biodiversity reservoirs and contribute to the trophic recycling of organic matter.

Keywords

Deep benthos Porifera Mediterranean Sea Biodiversity Pelagic–benthic coupling