Kelmo F et al. (2013), Tolerance of sponge assemblages to temperature ...

ECB-ART-50082

PLoS One 2013 Jan 01;810:e76441. doi: 10.1371/journal.pone.0076441.

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Tolerance of sponge assemblages to temperature anomalies: resilience and proliferation of sponges following the 1997-8 El-Niño southern oscillation.

Kelmo F , Bell JJ , Attrill MJ .

Abstract
Coral reefs across the world are under threat from a range of stressors, and while there has been considerable focus on the impacts of these stressors on corals, far less is known about their effect on other reef organisms. The 1997-8 El-Niño Southern Oscillation (ENSO) had notable and severe impacts on coral reefs worldwide, but not all reef organisms were negatively impacted by this large-scale event. Here we describe how the sponge fauna at Bahia, Brazil was influenced by the 1997-8 ENSO event. Sponge assemblages from three contrasting reef habitats (reef tops, walls and shallow banks) at four sites were assessed annually from 1995 to 2011. The within-habitat sponge diversity did not vary significantly across the study period; however, there was a significant increase in density in all habitats. Multivariate analyses revealed no significant difference in sponge assemblage composition (ANOSIM) between pre- and post-ENSO years for any of the habitats, suggesting that neither the 1997-8 nor any subsequent smaller ENSO events have had any measurable impact on the reef sponge assemblage. Importantly, this is in marked contrast to the results previously reported for a suite of other taxa (including corals, echinoderms, bryozoans, and ascidians), which all suffered mass mortalities as a result of the ENSO event. Our results suggest that of all reef taxa, sponges have the potential to be resilient to large-scale thermal stress events and we hypothesize that sponges might be less affected by projected increases in sea surface temperature compared to other major groups of reef organisms.

PubMed ID: 24116109
PMC ID: PMC3792017
Article link: PLoS One

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References [+] :

Aronson, Coral bleach-out in Belize. 2000, Pubmed

	Figure 1. The location of the coral reefs of northern Bahia (After Leão et al., 1997).
	Figure 2. Summary of wide-scale (A–B) and locally measured (C–F) environmental variables recorded from the studied reefs throughout the sampling period, demonstrating changes in ambient conditions during the El Niño period (1998).(A) Annual sea surface temperature and sunlight irradiance; (B) Annual rainfall and mean daily cloud cover; (C) Mean seawater temperature (ERT and CRW); (D) Mean salinity (ERT and CRW); (E) Mean seawater temperature and salinity (SBR); (F) Mean water clarity (CRW and SBR). Error bars indicate SE around the mean between replicate reef systems; Vertical bars represent the timing of the 1997–8 El Niño event.
	Figure 3. Changes in density and species richness (Mean ± SE) of the sponge assemblage recorded over a 17-year period (1995–2011) in Bahia, Brazil.Vertical bars represent the timing of the severe 1997–8 El Niño.
	Figure 4. Changes in density of Cliona spp., Cinachyrella spp. and Siphonodictyon spp. recorded from the three contrasting reef habitats from Bahia, Brazil.Vertical bars represent the timing of the 1997–8 El Niño event.
	Figure 5. Non-metric multidimensional scaling ordination of sponge assemblage data from the four assessed shallow-bank reefs from northern Bahia (Praia do Forte, Itacimirim, Guarajuba and Abai) throughout the sampling period, 1995–2011.Based on [ln (x+1)]) transformed species densities and Bray Curtis similarities. (A): ERT; (B): CRW; (C): SBR. Codes refer to the year of sampling (i.e. 00 = 2000).