Demosponges from the sublittoral and shallow-circalittoral (lt;24m depth) Antarctic Peninsula with a description of four new species and notes on br />in situ identification characteristics.

Specimens were collected by SCUBA diving from 22 sites along the Antarctic Peninsula, spanning latitudes from Diomedea Island (62°12.185'S) to Jenny Island (67°43.325'S). The aims of the survey were to record the sponge biodiversity of the sublittoral and shallow-circalittoral and to provide information on in situ identification features. In total 24 sponge species were recorded, ranging from 0 to 12 species per site. The most widespread species were Dendrilla antarctica (10 sites), Sphaerotylus antarcticus (11 sites); and Mycale (Oxymycale) acerata (13 sites). Four species new to science were discovered and are described here: Megaciella cardenasi sp. nov., Crella (Crella) hennequinae sp. nov., Hymedesmia (Hymedesmia) noramaloneae sp. nov., Clathria (Clathria) priestleyae sp. nov. Suberites topsenti (Burton, 1929) is reassigned to Hemimycale topsenti (Burton, 1929) comb. nov. General habitat notes are provided for the survey sites, many of which were previously unsurveyed.

Hexactinellida (Porifera) from the Drake Passage (Southern Ocean) with a description of three new species.

The Drake Passage has over 20 seamounts and ridges but it is notorious for large waves, fierce storms and strong currents that make benthic sampling difficult and therefore infrequent. Seamounts often have diverse sponge communities and may have high levels of endemism. Hexactinellida from Sars Seamount, an area in which the sponges had not previously been studied, and the Shackleton fracture zone were collected on a research cruise by the Nathaniel B Palmer in the Drake Passage, Southern Ocean. In total, from all cruise stations, 103 specimens of Hexactinellida were collected, however many appeared to be fragments of dead specimens and could not be identified due to missing microscleres. From Sars Seamount 127 sponge specimens were taken and from the Shackleton Fracture Zone 76 sponge specimens were taken; of these 36 and 16 respectively were Hexactinellida. From these two areas three new species of Hexactinellida are described: Doconesthes robinsoni sp. nov., Sympagella walleri sp. nov. and Caulophacus palmeri sp. nov and new records were made of Aulocalyx irregularis and Rossella antarctica.

Reduced diversity and high sponge abundance on a sedimented Indo-Pacific reef system: implications for future changes in environmental quality.

Although coral reef health across the globe is declining as a result of anthropogenic impacts, relatively little is known of how environmental variability influences reef organisms other than corals and fish. Sponges are an important component of coral reef fauna that perform many important functional roles and changes in their abundance and diversity as a result of environmental change has the potential to affect overall reef ecosystem functioning. In this study, we examined patterns of sponge biodiversity and abundance across a range of environments to assess the potential key drivers of differences in benthic community structure. We found that sponge assemblages were significantly different across the study sites, but were dominated by one species Lamellodysidea herbacea (42% of all sponges patches recorded) and that the differential rate of sediment deposition was the most important variable driving differences in abundance patterns. Lamellodysidea herbacea abundance was positively associated with sedimentation rates, while total sponge abundance excluding Lamellodysidea herbacea was negatively associated with rates of sedimentation. Overall variation in sponge assemblage composition was correlated with a number of variables although each variable explained only a small amount of the overall variation. Although sponge abundance remained similar across environments, diversity was negatively affected by sedimentation, with the most sedimented sites being dominated by a single sponge species. Our study shows how some sponge species are able to tolerate high levels of sediment and that any transition of coral reefs to more sedimented states may result in a shift to a low diversity sponge dominated system, which is likely to have subsequent effects on ecosystem functioning.