Effects of ocean acidification on sponge communities

Abstract

The effects of ocean acidification on lower invertebrates such as sponges may be pronounced because of their low capacity for acid-base regulation. However, so far, most studies have focused on calcifiers. We present the first study of the effects of ocean acidification on the Porifera. Sponge species composition and cover along pH gradients at CO 2 vents off Ischia (Tyrrhenian Sea, Italy) was measured at sites with normal pH (8.1-8.2), lowered pH (mean 7.8-7.9, min 7.4-7.5) and extremely low pH (6.6). There was a strong correlation between pH and both sponge cover and species composition. Crambe crambe was the only species present in any abundance in the areas with mean pH 6.6, seven species were present at mean pH 7.8-7.9 and four species (Phorbas tenacior, Petrosia ficiformis, Chondrilla nucula and Hemimycale columella) were restricted to sites with normal pH. Sponge percentage cover decreased significantly from normal to acidified sites. No significant effect of increasing CO 2 levels and decreasing pH was found on spicule form in Crambe crambe. This study indicates that increasing CO 2 concentrations will likely affect sponge community composition as some demosponge species appear to be more vulnerable than others. Further research into the mechanisms by which acidification affects sponges would be useful in predicting likely effects on sessile marine communities.

Acidification effects on biofouling communities: winners and losers

“…Leucosolenia produces calcite spicules that are protected in organic sheaths (Jones, ). Our data, however, do not support the prediction that calcareous sponges will necessarily be losers in the event of increased OA, although in naturally high CO 2 sites, siliceous sponges are more successful (Goodwin et al ., ). Previous work has indicated that settlement and recruitment is neither facilitated, nor inhibited by previous colonists in biofouling communities (Watson & Barnes, ; Bowden et al ., ), hence either low pH directly improved conditions for recruitment and growth of our ascidians, or numbers increased because of reduced competition.…”

Interactive effects of temperature and pCO2 on sponges: from the cradle to the grave

“…Studies focussing exclusively on the effects of OA at volcanic CO 2 seep sites have reported contrasting results. While sponge diversity was found to increase at low pH sites (pH 7.8–7.9) in the Mediterranean (Goodwin et al ., ), sponge diversity decreased at low pH sites (pH 7.73–8.00) in Papua New Guinea (Fabricius et al ., ), although particular species did become significantly more abundant at sites with active CO 2 bubbling (Morrow et al ., ). Although these studies provide some insight into sponge responses to a changing climate, the co‐occurrence of OW and OA requires studies that consider these factors concurrently (Dupont & Pörtner, ).…”

Restructuring of the sponge microbiome favors tolerance to ocean acidification

“…In contrast, it has been suggested that some sponge species may remain unaffected by OA (Durkworth et al ., ; Goodwin et al . ; Morrow et al ., ) and, overall, sponge taxa could benefit from acidic conditions (Bell et al ., ; Morrow et al ., ). However, the lack of knowledge about the mechanisms by which sponges respond to altered pH has become a limiting step in understanding how some sponge species resist OA.…”