Abstract
The glass sponge Aphrocallistes vastus contributes to the formation of large reefs unique to the Northeast Pacific Ocean. These habitats have tremendous filtration capacity that facilitates flow of carbon between trophic levels. Their sensitivity and resilience to climate change, and thus persistence in the Anthropocene, is unknown. Here we show that ocean acidification and warming, alone and in combination have significant adverse effects on pumping capacity, contribute to irreversible tissue withdrawal, and weaken skeletal strength and stiffness of A. vastus. Within one month sponges exposed to warming (including combined treatment) ceased pumping (50–60%) and exhibited tissue withdrawal (10–25%). Thermal and acidification stress significantly reduced skeletal stiffness, and warming weakened it, potentially curtailing reef formation. Environmental data suggests conditions causing irreversible damage are possible in the field at +0.5 °C above current conditions, indicating that ongoing climate change is a serious and immediate threat to A. vastus, reef dependent communities, and potentially other glass sponges.
Highlights
The glass sponge Aphrocallistes vastus contributes to the formation of large reefs unique to the Northeast Pacific Ocean
Sponges have an important functional role in ecosystems worldwide and over the entire marine bathymetric gradient where they efficiently filter water, link food webs, and facilitate the flow of carbon between trophic levels[1,2,3], alter the water column and its processes[4,5], and provide biogenic habitat[6]. This is true for the glass sponge Aphrocallistes vastus, which – along with Heterochone calyx and Farrea occa – form large biogenic reefs that cover several square kilometres of the seafloor off the west coast of Canada[7,8]
These reefs are built through larval sponges settling atop the fused dead skeletons of previous generations, and mechanical integrity of the sponge skeleton is vital to reef formation, persistence, and growth
Summary
A greater proportion of sponges exposed to warming and/or acidification treatments ceased pumping than the control sponges over the course of the experiment (Fig. 1a), but there was no significant effect of acidification, warming, or their interaction on apparent pumping arrest over time (Table 1a). The onset of apparent pumping arrest was seen as early as two weeks in sponges exposed to warming (including OW and OAW), and the proportion of individuals not filtering remained relatively stable in the OA and OW treatments, but there were fluctuations observed in the OAW treatment combination (Fig. 1a)
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