The macrofauna associated to the bamboo coral Isidella elongata: to what extent the impact on isideidae affects diversification of deep-sea fauna

Abstract

Macrofauna associated with the bamboo coral Isidella elongata was analysed in the Balearic Basin at depths of 697–1308 m. The diversity of associated macrofauna and the specific associations identified depended on different morphological characteristics of colonies, such as height or density of rami. Species associated with Isidella consisted mainly of sessile fauna, such as cnidarians (the actinian Amphianthus dornhii and the solitary coral Desmophyllum dianthus) and cirripeds (Gibossaverruca sp.). The strongest relationship (commensalism) occurred for the Pontogeneiidae amphipod Dautzenbergia megacheir, living attached to colonies of Isidella and represented by all population stages from adult (oostegal) females and males to juveniles. Species-coral relationships between Dautzenbergia and bamboo corals (Isididae) are plausible. Dautzenbergia spp. showed morphological differences between Atlantic (described by Walker 1897 as “eyes wanting”) and Mediterranean (with well-developed reddish eyes) specimens. This would suggest diversification of this genus, as has been recently suggested for Pleustidae associated with deep gorgonians. The diversity of the macrofaunal community associated with I. elongata was higher in the most mature (larger colonies with higher density) fields found NW of Mallorca, with higher colonies than in other parts of the Mediterranean. This was the only site where Gibossaverruca sp. (a first Mediterranean faunal record) and D. dianthus were collected. These complex associations between macrofauna and deep-water corals may provide arguments to protect these fragile ecosystems as a source of faunal diversity and diversification.

A new amphipod species of the bathyal genus Dautzenbergia Chevreux, 1900 (Amphipoda, Calliopioidea, Pontogeneiidae) associated with cold-water corals off Angola

“…nov. is associated with deep-water corals and their sponge assemblages. Species-coral relationships between Dautzenbergia and azooxanthellate scleractinian corals (Caryophylliidae, Isididae, and Oculinidae) and plexaurid gorgonians have been observed and reported previously (Stephensen 1944, Myers & Hall-Spencer 2004, Cartes et al 2022. In contrast to other species of the genus, D. concavipalma sp.…”

“…7, figs. 6-12;Stephensen 1944: 5, (Stephensen 1944); Mediterranean Sea: 650 m (Diviacco 1982), >1000 m (Cartes et al 2022). Found on a finely ramose gorgonid (see Stephensen 1944, p. 5) and the bamboo coral, Isidella elongata (see Cartes et al 2022).…”

Litophellia enoplosa sp. nov., a new species of sea anemone (Actiniaria, Metridioidea) from cold-water coral environments in the North-western Mediterranean Sea

“…Most of these species are distributed in the coastal and shallow waters, with only nine species of sea anemones (i.e., Actinauge richardi (Marion, 1906), Amphianthus dorhnii Koch (1878), Calliactis palliata (Fabricius, 1779) (listed as Adamsia palliata), Calliactis parasitica (Couch, 1842), Hormathia alba (Andres, 1881), H. coronata (Gosse, 1858), Kadophellia bathyalis Tur, 1989, Sagartia undata (Müller, 1778) (listed as Sagartiogeton undulatus), and Segonzactis hartogi Vafidis & Chintiroglou, 2002) distributed in waters deeper than 100 m (Vafidis & Chintiroglou, 2002). Recent studies of Mediterranean deep-sea and cold-water corals environments (e.g., Mas-trototaro et al, 2017;Taviani et al, 2019;Gerovasileiou et al, 2019;Angeletti et al, 2020;Cartes et al, 2022) have cited mainly two species of Mediterranean deep-sea anemones (A. dorhnii and Protanthea simplex Carlgren, 1891), adding another species of deep-sea anemone for the region. Nevertheless, the identity of some of the deepsea Mediterranean actiniarian records has been contested [e.g., H. alba was mistaken and described as Paracalliactis mediterranea Ross & Zamponi, 1982 according to Tur (1993)], others are deemed nomen dubium (e.g., K. bathyalis, see Rodríguez et al, 2023), and in other cases, the identity of the records must be corroborated because the studies did not have a taxonomic focus (e.g., P. simplex in Angeletti et al, 2020).…”

Healthy assemblages of Isidella elongata unintentionally protected from trawling offshore of Asinara Island (northwestern Sardinia, NW Mediterranean Sea)

“…It can form important facies (sensu Pérès and Picard 15 ) in the middle horizon of bathyal soft bottoms, mainly at depths greater than 500 m 4,18,19 . The height of its colonies hardly exceeds 80 cm in the Mediterranean Sea 14,20 .The bamboo coral plays multiple important ecological roles in the deep sea. It is a habitat-forming species able to form extensive aggregations of colonies that can increase the heterogeneity and three-dimensional complexity of the habitat (Ref.…”

“…It can form important facies (sensu Pérès and Picard 15 ) in the middle horizon of bathyal soft bottoms, mainly at depths greater than 500 m 4,18,19 . The height of its colonies hardly exceeds 80 cm in the Mediterranean Sea 14,20 .…”