The non-linear relationship between body size and function in parrotfishes

Lokrantz, Jerker; Nyström, Magnus; Thyresson, Matilda; Johansson, Charlotte

doi:10.1007/s00338-008-0394-3

Cited by 140 publications

(135 citation statements)

References 39 publications

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“…Yet, even on Yap where human population is lowest and reef size is moderate, many desirable species were harvested below their mean reproductive sizes, including the iconic green bumphead parrotfish and humphead wrasse, as well as several other common herbivores. The collective trends have known affiliations with high fishing effort, decreased catch-per-unit-effort, less sustainable fishery yields, diminished stocks, and reduced ecological function on coral reefs (Jennings and Polunin 1996;Pauly et al 1998;Jennings and Greenstreet 1999;Graham et al 2005;Cinner and McClanahan 2006;Anderson et al 2008a;Lokrantz et al 2008;McClanahan 2010). Clearly, there is a high demand for reef fish throughout Micronesia, and as demand for any exhaustible resources grows, exploitation intensity increases (Hotelling 1991).…”

Section: Discussionmentioning

confidence: 99%

Commercial coral-reef fisheries across Micronesia: A need for improving management

et al. 2011

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A dearth of scientific data surrounding Micronesia's coral-reef fisheries has limited their formal assessment and continues to hinder local and regional management efforts. We approach this problem by comparing catch-based datasets from market landings across Micronesia to evaluate fishery status in the Commonwealth of the Northern Mariana Islands (CNMI), Guam, Yap, and Pohnpei. Initial examinations found that calm weather and low lunar illumination predicted between 6% (Yap) and 30% (CNMI) of the variances in daily commercial landings. Both environmentally driven catch success and daily catch variability increased in accordance with reef-fish demand indices. Subsequent insight from species composition and size-at-capture data supported these findings, highlighting reduced trophic levels and capture sizes where higher human-population-per-reef-area existed. Among the 12-15 target species and/or species complexes that accounted for 70% of the harvest biomass, capture sizes were consistently smallest for CNMI and Guam, often below the reported mean reproductive sizes. Comparatively, Pohnpei has the greatest potential for reef fisheries, with a large reef area (303 km 2 ) and a moderate human population (34,000 people). However, the estimated harvest volume of 476 mt year -1 was 8-9 times higher than other jurisdictions. Even on Yap where the reef-fish demand index was lowest (67.7 people km -2 reef habitat), many target fish were harvested below their mean reproductive sizes, including the iconic green bumphead parrotfish and humphead wrasse, as well as several other herbivores. We discuss our results with respect to the contemporary doctrine surrounding size-spectra, catch composition, and catch frequencies that afford insight into fishery pressure and status. We posit that regional catch-based policies (initially) instituted at the market level, combined with area and gear-based restrictions, represent plausible vectors for improving Micronesian fisheries.

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Section: Discussionmentioning

confidence: 99%

Commercial coral-reef fisheries across Micronesia: A need for improving management

et al. 2011

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“…This correction was considered highly conservative, as parrotfishes in these areas were often <10 cm in total length (TL) (the size that allowed them to escape fish traps). Examples of calculations from the literature include equivalent grazing estimates of one large (>25 cm TL) to 24 small (5-10 cm TL) parrotfishes (38), and one large (35 cm) to 75 small (15 cm) parrotfishes (39).…”

Section: Methodsmentioning

confidence: 99%

Chemical defenses and resource trade-offs structure sponge communities on Caribbean coral reefs

Loh

Pawlik

2014

Proc. Natl. Acad. Sci. U.S.A.

145

196

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Ecological studies have rarely been performed at the community level across a large biogeographic region. Sponges are now the primary habitat-forming organisms on Caribbean coral reefs. Recent species-level investigations have demonstrated that predatory fishes (angelfishes and some parrotfishes) differentially graze sponges that lack chemical defenses, while co-occurring, palatable species heal, grow, reproduce, or recruit at faster rates than defended species. Our prediction, based on resource allocation theory, was that predator removal would result in a greater proportion of palatable species in the sponge community on overfished reefs. We tested this prediction by performing surveys of sponge and fish community composition on reefs having different levels of fishing intensity across the Caribbean. A total of 109 sponge species was recorded from 69 sites, with the 10 most common species comprising 51.0% of sponge cover (3.6-7.7% per species). Nonmetric multidimensional scaling indicated that the species composition of sponge communities depended more on the abundance of sponge-eating fishes than geographic location. Across all sites, multiple-regression analyses revealed that spongivore abundance explained 32.8% of the variation in the proportion of palatable sponges, but when data were limited to geographically adjacent locations with strongly contrasting levels of fishing pressure (Cayman Islands and Jamaica; Curaçao, Bonaire, and Martinique), the adjusted R 2 values were much higher (76.5% and 94.6%, respectively). Overfishing of Caribbean coral reefs, particularly by fish trapping, removes sponge predators and is likely to result in greater competition for space between fastergrowing palatable sponges and endangered reef-building corals.chemical ecology | indirect effects | community structure | marine protected areas | trophic dynamics

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“…Future studies, particularly examining the formation and stability of these groups (e.g., Crook 1999 ), would give us more insight into the behavioral mechanisms involved in group formation. In addition, integrating these aspects of group structure into studies that examine competition and aggression among reef fishes (e.g., Mun˜oz and Motta 2000 ;Mumby and Wabnitz 2002 ;Francini-Filho et al 2010 ) may increase our understanding of the complex community dynamics present in reef systems (e.g., Lokrantz et al 2008 ;Mumby 2009 ).…”

Section: Discussionmentioning

confidence: 99%

Size assortment in mixed-species groups of juvenile-phase striped parrotfish (Scarus iserti) in The Bahamas

et al. 2012

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Striped parrotfish (Scarus iserti) often form heterospecific groups with other reef fishes. In this study, we examined the species and body size composition of these groups on reefs in The Bahamas. Groups averaged approximately 4 S. iserti and 2 associated species, with surgeonfish (Acanthurus chirurgus and A. bahianus), slippery dick (Halichoeres bivittatus), and bluehead wrasse (Thalassoma bifasciatum) as the most common associates. Fewer groups than expected had only 1 associate; groups with 3 or more associates were more common than expected. Both the S. iserti and associated species tended to be closely sizematched within a group, perhaps due to benefits of size assortment in lowering predation risk. Likewise, the high frequency of groups with greater than a single associate species suggests that associates may benefit from not being the only phenotypically different individual in a group.

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The non-linear relationship between body size and function in parrotfishes

Cited by 140 publications

References 39 publications

Commercial coral-reef fisheries across Micronesia: A need for improving management

Commercial coral-reef fisheries across Micronesia: A need for improving management

Chemical defenses and resource trade-offs structure sponge communities on Caribbean coral reefs

Size assortment in mixed-species groups of juvenile-phase striped parrotfish (Scarus iserti) in The Bahamas

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