Lethal and sublethal impacts of a micropredator on post-settlement Caribbean reef fishes

Sellers, Joseph C.; Holstein, Daniel M.; Botha, Tarryn L.; Sikkel, Paul C.

doi:10.1007/s00442-018-4262-8

Cited by 17 publications

(12 citation statements)

References 78 publications

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“…DISCUSSION Predation is a central tenet in ecologypredators capture, kill and consume their prey (Lima and Dill, 1990). By contrast, micropredators attack multiple hosts, may briefly feed on blood, and can influence the mortality schedules of fish through changes in physiology, morphology and behaviour (Grutter et al, 2011(Grutter et al, , 2017Binning et al, 2013Binning et al, , 2014Artim et al, 2015;Triki et al, 2016;Sellers et al, 2019). Here, we demonstrate that experimental infection by a single gnathiid has a marked influence on the fast-start escape kinematics and the routine swimming behaviour of settlement-stage ambon damselfish.…”

Section: Cortisol Analysismentioning

confidence: 63%

Parasite infection directly impacts escape response and stress levels in fish

Allan

Illing

Fakan

et al. 2020

Journal of Experimental Biology

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Parasites can account for a substantial proportion of the biomass in marine communities. As such, parasites play a significant ecological role in ecosystem functioning via host interactions. Unlike macropredators, such as large piscivores, micropredators, such as parasites, rarely cause direct mortality. Rather, micropredators impose an energetic tax, thus significantly affecting host physiology and behaviour via sublethal effects. Recent research suggests that infection by gnathiid isopods (Crustacea) causes significant physiological stress and increased mortality rates. However, it is unclear whether infection causes changes in the behaviours that underpin escape responses or changes in routine activity levels. Moreover, it is poorly understood whether the cost of gnathiid infection manifests as an increase in cortisol. To investigate this, we examined the effect of experimental gnathiid infection on the swimming and escape performance of a newly settled coral reef fish and whether infection led to increased cortisol levels. We found that micropredation by a single gnathiid caused fast-start escape performance and swimming behaviour to significantly decrease and cortisol levels to double. Fast-start escape performance is an important predictor of recruit survival in the wild. As such, altered fitness-related traits and short-term stress, perhaps especially during early life stages, may result in large scale changes in the number of fish that successfully recruit to adult populations.

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Section: Cortisol Analysismentioning

confidence: 63%

Parasite infection directly impacts escape response and stress levels in fish

Allan

Illing

Fakan

et al. 2020

Journal of Experimental Biology

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“…While our data do demonstrate that on low‐coral plots, there is a higher likelihood of fish encountering a hyperabundance of gnathiid parasites, we have no evidence of an increase in average impact to fish on low‐coral reefs—the volume of blood extracted per fish biomass appears to remain constant across low‐ and high‐coral plots. Regardless, smaller fish and especially recently settled juveniles are more likely to suffer increased mortality due to gnathiid hyperabundance (Grutter et al 2017, Sellers et al 2019). Current molecular techniques (Hendrick et al 2019) provide tools to begin to characterize which fish species are being most impacted by gnathiid micropredation, which may clarify whether or not there may be a change in the flow of energy and nutrients that is due to gnathiid interaction with the fish within Brandl et al’s four functional compartments.…”

Section: Discussionmentioning

confidence: 99%

“…2013). Settlement‐stage fish are also parasitized by gnathiids (Penfold et al 2008, Artim et al 2015) with survivorship a function of fish size at time of settlement (Grutter et al 2017) but even sublethal levels of infestation have significant negative impacts on performance (Sellers et al 2019). Taken together, these results suggest that impacts to host fish range from mild to severe and are dependent on gnathiid parasite abundance, especially relative to local fish abundance.…”

Section: Introductionmentioning

confidence: 99%

Abundance of a cryptic generalist parasite reflects degradation of an ecosystem

et al. 2020

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Ecosystem degradation due to anthropogenic activities is the primary issue of our times. Theoretical analyses as well as efforts to restore and manage ecosystems depend on comprehensive metrics of ecosystem function. In the case of complex ecosystems such as tropical coral reefs-especially where monitoring, management, and restoration are important-multiple metrics reflecting key functional groups are required to accurately reflect ecosystem function and when necessary, diagnose degree and kind of ecosystem degradation. We propose inclusion of the generalist ectoparasite functional group as a measure of ecosystem function of coral reefs. This functional group is adaptable to loss of other community members and may experience an increase in abundance as ecosystem function declines. Fish-parasitic gnathiid isopods are a member of this group, resident though inconspicuous in coral-reef communities. On Caribbean coral reefs, based on 938 light-trap samples, we observed a negative correlation between abundance of smallersized gnathiids and abundance of live coral, a natural predator of gnathiids. Plots grouped by coral cover-a measure of success of the ecosystem engineer-and ectoparasite abundance varied significantly in community composition including abundance of macroalgae, turf algae, and farming Stegastes spp. damselfish reflecting shifts in community structure. Changes in gnathiid abundance with respect to the abundance of organisms participating in each of the core functional processes driving coral-reef ecosystems reflect broad connectivity of gnathiid parasites across the ecosystem. We conclude that the hyperabundance of a small, cryptic, generalist parasite, when used in combination with a metric of abundance of the primary ecosystem engineer, can provide one nuanced measure of the ecosystem vulnerability to collapse.

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“…In large numbers, they can even kill adult fish (Mugride and Stallybrass 1983;Hayes et al 2011). Fish larvae and juveniles are particularly sensitive to such ectoparasites, with only a few gnathiids necessary to kill their host (Grutter et al 2008(Grutter et al , 2017Artim et al 2015;Sellers et al 2019).…”

Section: Introductionmentioning

confidence: 99%

The role of corals on the abundance of a fish ectoparasite in the Great Barrier Reef

et al. 2021

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Gnathiid isopods, common fish ectoparasites, can affect fish physiology, behaviour and survival. Gnathiid juveniles emerge from the benthos to feed on fish blood. In the Caribbean, gnathiids are positively associated with dead coral and negatively associated with live coral, due to coral predation on gnathiids. However, such interactions were unstudied in the Great Barrier Reef (GBR). Due to recent extreme weather events (two cyclones and one mass warm-water coral bleaching event, 2014-2016), it is now urgent to understand the role of corals on the abundance of these ectoparasites. Here, to understand parasite-coral dynamics at the micro-habitat level, we examined substrate associations of gnathiid isopods on Lizard Island (GBR) using demersal plankton emergence traps. Additionally, we determined whether two abundant hard coral species, Goniopora lobata and Pocillopora damicornis, predate on gnathiids in a laboratory experiment using containers with gnathiids and fragments from each coral species or dead coral as controls. The abundance of gnathiids over natural substrates was higher for dead compared to live hard coral and sand, but not live soft coral. Moreover, we found that free-swimming gnathiids decreased in containers with live coral compared to dead coral controls. This was attributed to predation as we also directly observed a coral ingesting a gnathiid. Our results suggest that dead coral is a suitable microhabitat for gnathiids, but that live coral is not since live corals can predate on gnathiids. We propose that following extreme events, such as cyclones and heat waves, gnathiids might benefit from more dead coral substrate and a decrease in predation by the reduction in coral cover on the reef. We advocate that an increase in the frequency of extreme events may have cascading effects for the fish population through changes in the population of benthos-dependent ectoparasites.

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Lethal and sublethal impacts of a micropredator on post-settlement Caribbean reef fishes

Cited by 17 publications

References 78 publications

Parasite infection directly impacts escape response and stress levels in fish

Parasite infection directly impacts escape response and stress levels in fish

Abundance of a cryptic generalist parasite reflects degradation of an ecosystem

The role of corals on the abundance of a fish ectoparasite in the Great Barrier Reef

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