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CURATOR
A pinboard by
Molly Scott

I'm a PhD researcher from Australia studying the impacts of global warming on tropical fisheries

PINBOARD SUMMARY

How do increasing ocean temperatures impact fish species habitat use, movement, and feeding?

Global climate change, particularly ocean warming, is increasingly considered one of the major threats to tropical coastal fisheries, potentially undermining important revenue and food security provided by coral reef ecosystems. Millions of people from tropical nations are directly reliant on food harvested from coral reefs and fish is the most common constituent of dietary protein. Tropical marine fishes however, are particularly vulnerable to ocean warming, because many species are already exposed to summer temperatures that may have negative consequences for individual health and fitness.

Why study coral trout?

Coral trout are amongst the most important tropical fisheries species, targeted by commercial and artisanal fishers throughout the Indo-Pacific. More information is needed to determine the impacts of increasing ocean temperature on coral trout to see if and how they are able to withstand higher water temperatures, with a view to better understand the impacts of climate change on wild stocks of these important fishes.

Which aspects of coral trout behaviour do I study?

My research focuses on three aspects of coral trout behaviour that are critical to their survival: habitat use, movement patterns, and feeding rates. Any change to these behaviours as a result of rising ocean temperatures may affect their catchability, productivity and viability of wild fisheries stocks.

My vision is for my research to inform management decisions related to coral trout, and other targeted fisheries species throughout the Indo-Pacific region to enable the sustainable use of wild stocks into the future.

8 ITEMS PINNED

Effects of climate change on coral grouper ( Plectropomus spp.) and possible adaptation options

Abstract: Abstract Global climate change is increasingly considered one of the major threats to tropical coastal fisheries, potentially undermining important revenue and food security provided by coral reef ecosystems. While there has been significant and increasing work on understanding specific effects of climate change on coral reef fishes, few studies have considered large-bodied fisheries target species, limiting understanding of the effects of climate change on tropical fisheries. This review focuses on coral grouper (Plectropomus spp., and mainly Plectropomus leopardus), which are heavily fished throughout the Indian and Pacific oceans, and represent an exemplar group to assess potential effects of climate change on coral reef fisheries. In experimental studies, P. leopardus appear to be extremely sensitive to increasing ocean temperature, exhibiting declines in survivorship, aerobic scope and activity with relatively moderate increases in temperature. As such, ongoing ocean warming may jeopardize the catchability of coral grouper and sustainability of reef-based fisheries, especially at low latitudes. Notably, a significant portion of wild stocks of P. leopardus are already exposed to temperatures (≥30 °C) that have been shown to compromise individual performance and body condition. While there are considerable knowledge gaps in predicting effects of global climate change on coral grouper, such as their capacity to avoid, acclimate or adapt to changes in local environmental conditions, current information suggests that there is cause for concern. As such, we take the formative steps to outline both ecological and socioeconomic adaptations that could reduce vulnerability of coral reef fisheries to climate impacts on stocks of coral grouper, using a linked socio-economic framework.AbstractGlobal climate change is increasingly considered one of the major threats to tropical coastal fisheries, potentially undermining important revenue and food security provided by coral reef ecosystems. While there has been significant and increasing work on understanding specific effects of climate change on coral reef fishes, few studies have considered large-bodied fisheries target species, limiting understanding of the effects of climate change on tropical fisheries. This review focuses on coral grouper (Plectropomus spp., and mainly Plectropomus leopardus), which are heavily fished throughout the Indian and Pacific oceans, and represent an exemplar group to assess potential effects of climate change on coral reef fisheries. In experimental studies, P. leopardus appear to be extremely sensitive to increasing ocean temperature, exhibiting declines in survivorship, aerobic scope and activity with relatively moderate increases in temperature. As such, ongoing ocean warming may jeopardize the catchability of coral grouper and sustainability of reef-based fisheries, especially at low latitudes. Notably, a significant portion of wild stocks of P. leopardus are already exposed to temperatures (≥30 °C) that have been shown to compromise individual performance and body condition. While there are considerable knowledge gaps in predicting effects of global climate change on coral grouper, such as their capacity to avoid, acclimate or adapt to changes in local environmental conditions, current information suggests that there is cause for concern. As such, we take the formative steps to outline both ecological and socioeconomic adaptations that could reduce vulnerability of coral reef fisheries to climate impacts on stocks of coral grouper, using a linked socio-economic framework.PlectropomusPlectropomus leopardusP. leopardusP. leopardus

Pub.: 19 Dec '16, Pinned: 28 Jul '17

Increasing ocean temperatures reduce activity patterns of a large commercially important coral reef fish.

Abstract: Large-bodied fish are critical for sustaining coral reef fisheries, but little is known about the vulnerability of these fish to global warming. This study examined the effects of elevated temperatures on the movement and activity patterns of the common coral trout Plectropomus leopardus (Serranidae), which is an important fishery species in tropical Australia and throughout the Indo West-Pacific. Adult fish were collected from two locations on Australia's Great Barrier Reef (23°S and 14°S) and maintained at one of four temperatures (24, 27, 30, 33 °C). Following >4 weeks acclimation, the spontaneous swimming speeds and activity patterns of individuals were recorded over a period of 12 days. At 24-27 °C, spontaneous swimming speeds of common coral trout were 0.43-0.45 body lengths per second (bls(-1)), but dropped sharply to 0.29 bls(-1) at 30 °C and 0.25 bls(-1) at 33 °C. Concurrently, individuals spent 9.3-10.6% of their time resting motionless on the bottom at 24-27 °C, but this behaviour increased to 14.0% at 30 °C and 20.0% of the time at 33 °C (mean ± SE). The impact of temperature was greatest for smaller individuals (<45 cm TL), showing significant changes to swimming speeds across every temperature tested, while medium (45-55 cm TL) and large individuals (>55 cm TL) were first affected by 30 °C and 33 °C, respectively. Importantly, there was some indication that populations can adapt to elevated temperature if presented with adequate time, as the high-latitude population decreased significantly in swimming speeds at both 30 °C and 33 °C, while the low-latitude population only showed significant reductions at 33 °C. Given that movement and activity patterns of large mobile species are directly related to prey encounter rates, ability to capture prey and avoid predators, any reductions in activity patterns are likely to reduce overall foraging and energy intake, limit the energy available for growth and reproduction, and affect the fitness and survival of individuals and populations.

Pub.: 28 Nov '13, Pinned: 04 Sep '17

Global warming will disproportionately affect larger adults in a predatory coral reef fish.

Abstract: Global warming is expected to reduce body sizes of ectothermic animals. Although the underlying mechanisms of size reductions remain poorly understood, effects appear stronger at latitudinal extremes (poles and tropics) and in aquatic rather than terrestrial systems. To shed light on this phenomenon, we examined the size-dependence of critical thermal maxima (CTmax) and aerobic metabolism in a commercially important tropical reef fish, the leopard coral grouper (Plectropomus leopardus) following acclimation to current-day (28.5°C) versus projected end-of-century (33°C) summer temperatures for the northern Great Barrier Reef (GBR). CTmax declined from 38.3°C to 37.5°C with increasing body mass in adult fish (0.45-2.82 kg), indicating that larger individuals are more thermally sensitive than smaller conspecifics. This may be explained by a restricted capacity for large fish to increase mass-specific maximum metabolic rate (MMR) at 33°C compared with 28.5°C. Indeed, temperature influenced the relationship between metabolism and body mass (0.02-2.38 kg), whereby the scaling exponent for MMR increased from 0.74±0.02 at 28.5°C to 0.79±0.01 at 33°C, and the corresponding exponents for standard metabolic rate (SMR) were 0.75±0.04 and 0.80±0.03. The increased metabolic scaling exponents at higher temperatures suggest that energy budgets may be disproportionately impacted in larger fish and contribute to reduced maximum adult size. Such climate-induced reductions in body size would have important ramifications for fisheries productivity, but are also likely to have knock-on effects for trophodynamics and functioning of ecosystems. This article is protected by copyright. All rights reserved.

Pub.: 04 Nov '16, Pinned: 04 Sep '17

Contrasting patterns of vertical and horizontal space use of two exploited and sympatric coral reef fish

Abstract: Abstract Understanding spatial distribution and temporal variation in movement patterns of closely related species is relevant for deciphering how resources are selected and whether interactions between species affect resource use patterns. The horizontal space use and vertical space use of two exploited reef fish, Plectropomus leopardus and P. laevis (all adults), were compared at mid-shelf Helix Reef and Lodestone Reef in the Great Barrier Reef over ~3 years using passive acoustic telemetry. Both species were detected throughout the 12-month duration of transmitters (mean detection period: ~270 days) and often made deep movements to ~40 m possibly related to reproductive behaviour (spawning). Differences in space use were apparent between species, with P. laevis consistently using greater area around reefs throughout the year. Overall, depth use patterns were similar between species; however, when daily detections were grouped in 2-h periods, P. laevis remained shallower and had greater variation in depth use compared to P. leopardus. Contrasting patterns of space use between these co-occurring species, in conjunction with known dietary dissimilarities, indicate distinct habitat use and resource preferences that are important for conservation and fisheries management.AbstractUnderstanding spatial distribution and temporal variation in movement patterns of closely related species is relevant for deciphering how resources are selected and whether interactions between species affect resource use patterns. The horizontal space use and vertical space use of two exploited reef fish, Plectropomus leopardus and P. laevis (all adults), were compared at mid-shelf Helix Reef and Lodestone Reef in the Great Barrier Reef over ~3 years using passive acoustic telemetry. Both species were detected throughout the 12-month duration of transmitters (mean detection period: ~270 days) and often made deep movements to ~40 m possibly related to reproductive behaviour (spawning). Differences in space use were apparent between species, with P. laevis consistently using greater area around reefs throughout the year. Overall, depth use patterns were similar between species; however, when daily detections were grouped in 2-h periods, P. laevis remained shallower and had greater variation in depth use compared to P. leopardus. Contrasting patterns of space use between these co-occurring species, in conjunction with known dietary dissimilarities, indicate distinct habitat use and resource preferences that are important for conservation and fisheries management.Plectropomus leopardusP. laevisP. laevisP. laevisP. leopardus

Pub.: 17 Nov '16, Pinned: 04 Sep '17

Rising temperatures may drive fishing-induced selection of low-performance phenotypes.

Abstract: Climate warming is likely to interact with other stressors to challenge the physiological capacities and survival of phenotypes within populations. This may be especially true for the billions of fishes per year that undergo vigorous exercise prior to escaping or being intentionally released from fishing gear. Using adult coral grouper (Plectropomus leopardus), an important fisheries species throughout the Indo-Pacific, we show that population-level survival following vigorous exercise is increasingly compromised as temperatures increase from current-day levels (100-67% survival at 24-30 °C) to those projected for the end of the century (42% survival at 33 °C). Intriguingly, we demonstrate that high-performance individuals take longer to recover to a resting metabolic state and subsequently have lower survival in warm water compared with conspecifics that exercise less vigorously. Moreover, we show that post-exercise mortality of high-performance phenotypes manifests after 3-13 d at the current summer maximum (30 °C), while mortality at 33 °C occurs within 1.8-14.9 h. We propose that wild populations in a warming climate may become skewed towards low-performance phenotypes with ramifications for predator-prey interactions and community dynamics. Our findings highlight the susceptibility of phenotypic diversity to fishing activities and demonstrate a mechanism that may contribute to fishing-induced evolution in the face of ongoing climate change.

Pub.: 18 Jan '17, Pinned: 04 Sep '17