Long‐term temporal and spatial patterns in bioeroding sponge distribution at the Abrolhos Bank, Brazil, Southwestern Atlantic

Abstract

Bioeroding sponges belong to the most dominant bioeroders, significantly contributing to the erosion of coral reefs. Some species are tolerant or even benefit from environmental conditions such as ocean warming, acidification, and eutrophication. In consequence, increases in sponge bioerosion have been observed on some coral reefs over the last decades. The Abrolhos Bank is the largest coral reef system in the South Atlantic. It has been affected by sedimentation, eutrophication, overfishing, and climate change, mainly affecting coastal reefs, and at lesser intensity outer ones as well. This study aimed to describe spatial and temporal patterns in bioeroding sponge distribution in carbonate substrates in the Abrolhos Bank. Photo‐quadrats were used to compare bioeroding sponge abundance between two shallow reefs: a coastal, Pedra de Leste (PL), and an outer reef, Parcel dos Abrolhos (PAB). Each individual was delimitated over the substrate by determining the sponge surface through a line connecting the outermost papillae. The study was conducted over 6 years in 2008–2009 and 2013–2016. Four species of bioeroding sponges were identified: Cliona carteri Ridley, 1881, C. delitrix Pang, 1973, C. cf. schmidtii Ridley, 1881, and Siphonodictyon coralliphagum Rützler, 1971. The distribution and abundance of species varied between the inner and outer reefs and across the years, and displayed certain selectivity for the calcareous substrates recorded. Crustose coralline algae (CCA) were the main substrate excavated by the most abundant bioeroding species, C. carteri, and represented 70% of the substrate types occupied by this sponge (CCA, coral overgrown by CCA and plain coral). The highest abundance of bioeroding sponges observed in photo‐quadrats was 21.3 individuals/m2 at the outer reefs (PAB) in 2014. The abundances or areal extents of bioeroding sponges were up to 10 times greater on the outer reefs than on the coastal ones, where sedimentation is higher and more strongly influenced by siliciclastic material. Moreover, a higher herbivorous fish biomass has been reported on outer reefs which could also influence the higher abundance of bioeroding sponges in outer reefs. During the study period of 6 years, an increase in bioeroding sponge abundance was observed at the outer reefs (PAB), with the sea surface temperature increase. As CCA have an important role in reefal cementation and carbonate production in the Abrolhos reefs, a bioerosion impact might be expected, in particular, on the outer reefs.

Decadal (2006-2018) dynamics of Southwestern Atlantic’s largest turbid zone reefs

“…However, higher coral covers were observed on nearshore walls, which is consistent with previous observations of persistent coral assemblages under turbid conditions [ 20 ]. The relatively high abundance of sponges and CCA on walls seems related to their high tolerance to low light regimes [ 59 , 60 ]. Offshore, macroalgal cover was minimal, while some nearshore reefs were dominated by unpalatable forms (e.g., Canistrocarpus , Lobophora ) that are weakly controlled by herbivores fishes [ 61 , 62 ] due to either structural or chemical defenses.…”

Effects of elevated temperature and eutrophication on tropical lagoon sponges

“…The temporal variability of sponges has previously been described from the Caribbean (Zea, 1994;Wulff, 2006a), Indo-Pacific (Biggerstaff et al, 2017;Rovellini et al, 2019), tropical Atlantic (Kelmo et al, 2013;de Moraes et al, 2019), Mediterranean (Koopmans & Wijffels, 2008;Di Camillo et al, 2012) and Great Barrier Reef (Ramsby et al, 2017), but there have been no studies from the Indian Ocean. From these earlier studies, multiple biotic and abiotic factors, including macroalgal competition (Ávila et al, 2015;Ramsby et al, 2017), seawater temperature (Carballo et al, 2008;Kelmo et al, 2013), salinity (Corriero et al, 2007;Longo et al, 2015) and cyanobacterial blooms (Butler et al, 1995;Stevely et al, 2010), have been reported to correlate with sponge temporal variability.…”

“…The reduced spatial competition between corals and sponges provided sponges more space to proliferate. Furthermore, a six-year study on South Atlantic sponge reefs showed that the abundance of bioeroding sponges increased over time, which was correlated with elevated sea surface temperature (de Moraes et al, 2019). However, while multiple studies have been conducted on the temporal variability of reef sponges, few studies have explored temporal variation in lagoon-inhabiting sponges.…”

Effects of elevated temperature and eutrophication on tropical lagoon sponges

“…In the last two decades, multiple studies have investigated the impacts of climate change (Massaro et al, 2012;Bennett et al, 2017;Ramsby et al, 2018) and eutrophication on tropical sponges. While there have been multiple evidences indicating that sponges are more likely tolerant to other dominant calcifying benthic taxa such as corals (Bell et al, 2013;Kelmo et al, 2013;de Moraes et al, 2019), the mechanisms underlying the tolerance or acclimation of sponges (mostly bioeroding species) to climate change (Fang et al, 2014;Bell et al, 2018) and eutrophication are relatively unknown. Future work should therefore be focussed on the understanding the specific physiological and cellular mechanisms, which enable sponges to acclimate to enviromental stress.…”

“…The temporal variability of sponges has previously been described from the Caribbean (Zea, 1994;Wulff, 2006a), Indo-Pacific (Biggerstaff et al, 2017;Rovellini et al, 2019), tropical Atlantic (Kelmo et al, 2013;de Moraes et al, 2019), Mediterranean (Koopmans & Wijffels, 2008;Di Camillo et al, 2012) and Great Barrier Reef (Ramsby et al, 2017), but there have been no studies from the Indian Ocean. From these earlier studies, multiple biotic and abiotic factors, including macroalgal competition (Ávila et al, 2015;Ramsby et al, 2017), seawater temperature (Carballo et al, 2008;Kelmo et al, 2013), salinity (Corriero et al, 2007;Longo et al, 2015) and cyanobacterial blooms (Butler et al, 1995;Stevely et al, 2010), have been reported to correlate with sponge temporal variability.…”