Diversity and Distribution Patterns in High Southern Latitude Sponges

Abstract

Sponges play a key role in Antarctic marine benthic community structure and dynamics and are often a dominant component of many Southern Ocean benthic communities. Understanding the drivers of sponge distribution in Antarctica enables us to understand many of general benthic biodiversity patterns in the region. The sponges of the Antarctic and neighbouring oceanographic regions were assessed for species richness and biogeographic patterns using over 8,800 distribution records. Species-rich regions include the Antarctic Peninsula, South Shetland Islands, South Georgia, Eastern Weddell Sea, Kerguelen Plateau, Falkland Islands and north New Zealand. Sampling intensity varied greatly within the study area, with sampling hotspots found at the Antarctic Peninsula, South Georgia, north New Zealand and Tierra del Fuego, with limited sampling in the Bellingshausen and Amundsen seas in the Southern Ocean. In contrast to previous studies we found that eurybathy and circumpolar distributions are important but not dominant characteristics in Antarctic sponges. Overall Antarctic sponge species endemism is ∼43%, with a higher level for the class Hexactinellida (68%). Endemism levels are lower than previous estimates, but still indicate the importance of the Polar Front in isolating the Southern Ocean fauna. Nineteen distinct sponge distribution patterns were found, ranging from regional endemics to cosmopolitan species. A single, distinct Antarctic demosponge fauna is found to encompass all areas within the Polar Front, and the sub-Antarctic regions of the Kerguelen Plateau and Macquarie Island. Biogeographical analyses indicate stronger faunal links between Antarctica and South America, with little evidence of links between Antarctica and South Africa, Southern Australia or New Zealand. We conclude that the biogeographic and species distribution patterns observed are largely driven by the Antarctic Circumpolar Current and the timing of past continent connectivity.

Patrones de diversidad y estructura genética en especies antárticas y subantárticas de Nacella (Nacellidae)

“…El advenimiento de nuevas aproximaciones metodológicas en biología molecular y genética de poblaciones ha revolucionado los estudios en biogeografía, particularmente en la biota del Océano Austral Griffiths et al 2009;Fraser et al 2009;González-Wevar et al 2010Downey et al 2012;Pierrat et al 2013;Poulin et al 2014). El uso de distintas fuentes de información provenientes de la paleontología, paleoclimatología y de la paleogeografía, junto a aquellos obtenidos de secuencias de DNA hace posible la interpretación de los patrones actuales de distribución en un marco biogeográfico más preciso (Pearse et al 2009).…”

Two new species of calcareous sponges (Porifera: Calcarea) from the deep Antarctic Eckström Shelf and a revised list of species found in Antarctic waters

“…Of particular interest was the discovery of five isolated specimens of calcareous sponges, three new to science, collected from five different bathyal and abyssal stations in the Weddell Sea . , examination of original material and collections held by the authors and a re-evaluation of the records used in a recent publication on the distribution of sponges in the Southern Oceans (Downey et al 2012). All together 50 species of calcareous sponges are considered to be part of the Antarctic sponge fauna (here defined as below 50 °S).…”

“…The Antarctic sponge fauna has been characterized by a high degree of endemism (Janussen & Tendal 2007;Downey et al 2012), many eurybathic species (Janussen & Tendal 2007) and a circumpolar distribution pattern (Janussen & Tendal 2007;Downey et al 2012). The Weddell Sea area is of special interest from a zoogeographical point of view as it seems to be a strong link between the sponge faunas of the Antarctic and South America (Downey et al 2012).…”

Publication impact in sponge chemical and microbial ecology

“…Sponges are considered an ecologically important group in marine benthic communities (McClintock et al 2005, Downey et al 2012, as evidenced in our search record. The vast majority of studies in chemical ecology deal with the biological activity of natural products from sponges (Wright et al 2011, Freeman and Gleason 2012, Nuñez-Pons et al 2012 and their biotechnological potential (Leal et al 2012a, b, Acevedo et al 2013, Kampa et al 2013).…”