Coral bleaching in turbid waters of north-western Australia

Abstract

We report severe bleaching in a turbid water coral community in north-western Australia. Towed still imagery was used for a benthic survey near Onslow in March 2013 to assess thermal stress in hard and soft corals, finding 51–68% of all corals fully bleached in 10–15-m water depth. Tabulate or foliaceous Turbinaria was the locally most abundant hard coral (46%), followed by massives such as faviids and poritids (25%) and encrusting coral (12%), thus over 80% of the local corals could be considered to be bleaching resistant. All coral groups were bleached in similar proportions (massive hard corals 51%<soft corals 60%<encrusting hard corals 62%<Turbinaria 62%<‘others’ 68%). NOAA data and environmental assessments suggest previous recurrent thermal stress throughout the last 10 years in the study area. On the basis of these records this stress apparently changed the community structure from bleaching vulnerable species such as Acropora, leaving more tolerant species, and reduced coral cover. We could see no evidence for adaptation or acclimation of corals in this area. Towed still imagery was found to be a suitable means for rapid and large-scale bleaching studies in shallow, turbid areas where diving can be difficult or impossible.

A novel stereo‐video method to investigate fish–habitat relationships

“…Previous studies have demonstrated positive relationships between live coral cover and the abundance and diversity of fish assemblages (Carpenter et al 1981;Connell & Kingsford 1998;Komyakova, Munday & Jones 2013). However, in the current study, the per cent cover of (live) hard and soft corals was low (~8% combined) compared to dead corals (~25%) possibly due to a bleaching event in March 2013 (Lafratta et al 2016) (Fig. S6); hence, the observed relationships between fish assemblages and dead coral cover (as also indicated by macroalgae) were stronger.…”

“…However, in the current study, the per cent cover of (live) hard and soft corals was low (~8% combined) compared to dead corals (~25%) possibly due to a bleaching event in March 2013 (Lafratta et al . ) (Fig. S6); hence, the observed relationships between fish assemblages and dead coral cover (as also indicated by macroalgae) were stronger.…”

Gradients of disturbance and environmental conditions shape coral community structure for south‐eastern Indian Ocean reefs

“…Indeed, in the last two decades, abnormally intense warm‐water events have affected both high and low‐latitude reefs in the SEIO, of which the 2011 heatwave was the most severe (Abdo, Bellchambers, & Evans, ; Depczynski et al., ; Feng, McPhaden, Xie, & Hafner, ; Hobbs & McDonald, ; Moore et al., ; Wernberg et al., ; Zhang, Feng, Hendon, Hobday, & Zinke, ; Zinke et al., ). Moreover, since 2011, anomalously warm SSTs have caused persistent summer heat stress and severe coral bleaching at many SEIO reefs (Caputi, Jackson, & Pearce, ; Feng et al., ; Lafratta, Fromont, Speare, & Schönberg, ). These stresses are likely to interact with aspects of background temperature variation to produce changes in coral communities that may not be linearly related to historical temperature variation.…”

How Reliable Is Structure from Motion (SfM) over Time and between Observers? A Case Study Using Coral Reef Bommies

“…Record temperatures in early 2016 caused unprecedented levels of coral bleaching and mortality [3][4][5]. Despite these widespread perturbations on coral reefs, research conducted by Cinner et al [6] has revealed many 'bright spot' and 'dark spot' reefs that, for unexplained reasons, are more or less resilient to climate change.…”