The importance of grazing intensity and frequency for physiological responses of the tropical seagrass Thalassia hemprichii

Eklöf, Johan; Gullström, Martin; Björk, Mats; Asplund, Maria E.; Hammar, Lena Marmstål; Dahlgren, Annika; Öhman, Marcus

doi:10.1016/j.aquabot.2008.03.009

Cited by 21 publications

(18 citation statements)

References 16 publications

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“…Wetland plants suffer also from a diversity of herbivory effects (Lodge, 1991;Schmieder et al, 2006;Van den Wyngaert et al, 2003). Herbivory has been shown to influence plant photosynthesis (Retuerto et al, 2004), growth rates (Cebriá n et al, 1998;Meyer, 1998;Schooler et al, 2007;Engloner, 2009), mortality of species (Reichman and Smith, 1991), inflorescence production (Canto et al, 2004;Mauricio, 1993) and physiological characters (Eklöf et al, 2008). Plant responses to herbivory depend on the type of tissue removed (i. e. root, leaf, stem, meristem, tuber) (Hjälté n et al, 1993;Raghu et al, 2006), the frequency and intensity of herbivory (Hayball and Pearce, 2004), the timing of herbivory and the availability of resources in the environment (McNaughton, 1983;Rosenthal and Kotanen, 1994).…”

Section: Introductionmentioning

confidence: 99%

Flooding effects on rapid responses of the invasive plant Alternanthera philoxeroides to defoliation

Liu

et al. 2010

Flora - Morphology, Distribution, Functional Ecology of Plants

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Section: Introductionmentioning

confidence: 99%

Flooding effects on rapid responses of the invasive plant Alternanthera philoxeroides to defoliation

Liu

et al. 2010

Flora - Morphology, Distribution, Functional Ecology of Plants

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“…Removing fish biomass in such intensity, as reported here, can significantly alter the trophic structure of seagrass and adjacent habitats, especially when slow-developing and economically important species are removed (Unsworth and Cullen 2010). Given that seagrass communities are defined by top-down predator control (Eklof et al 2009;Burkholder et al 2013), a significant loss of these predatory species can result in higher intensity (and frequency) urchin grazing events, resulting in a loss of seagrass structure and function (Eklof et al 2008b). Coral reef fisheries provide substantial support for communities within Palma Bay.…”

Section: Discussionmentioning

confidence: 73%

The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

Jones

Unsworth

2019

Ambio

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Malaria is a serious global health issue, with around 200 million cases per year. As such, great effort has been put into the mass distribution of bed nets as a means of prophylaxis within Africa. Distributed mosquito nets are intended to be used for malaria protection, yet increasing evidence suggests that fishing is a primary use for these nets, providing fresh concerns for already stressed coastal ecosystems. While research documents the scale of mosquito net fisheries globally, no quantitative analysis of their landings exists. The effects of these fisheries on the wider ecosystem assemblages have not previously been examined. In this study, we present the first detailed analysis of the sustainability of these fisheries by examining the diversity, age class, trophic structure and magnitude of biomass removal. Dragnet landings, one of two gear types in which mosquito nets can be utilised, were recorded across ten sites in northern Mozambique where the use of Mosquito nets for fishing is common. Our results indicate a substantial removal of juveniles from coastal seagrass meadows, many of which are commercially important in the region or play important ecological roles. We conclude that the use of mosquito nets for fishing may contribute to food insecurity, greater poverty and the loss of ecosystem functioning.

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“…Simulated grazing is commonly used to test grazing effects on seagrasses (see e.g. Cebrián et al 1998;Eklöf et al 2008a), but it cannot be ruled out that effects of actual grazing differ from those reported here (see Ibarra-Obando et al 2004 and references therein). Treatments were established in an orthogonal and replicated design, resulting in six treatments (UC, UL, UR, SC, SL and SR).…”

Section: Experiments 2: Effects Of Shading and Simulated Swan Grazingmentioning

confidence: 80%

“…While grazing generally reduces biomass (Hughes et al 2004), there is generally a parabolic response in seagrass growth to grazing intensity (Valentine et al 1997;Cebrián et al 1998;Ibarra-Obando et al 2004); moderate to intermediate grazing can increase production through use of stored carbohydrates. The nature of the response curve differs extensively between populations, probably because carbohydrate content is affected by environmental conditions (Cebrián et al 1998) including grazing history (Eklöf et al 2008a). The response also varies between species as larger 'climax'species of seagrass have greater carbohydrate reserves to utilise compared with smaller 'pioneer' species.…”

Section: Introductionmentioning

confidence: 99%

Effects of multiple disturbances in seagrass meadows: shading decreases resilience to grazing

Eklöf

McMahon

Lavery

2009

Mar. Freshwater Res.

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Abstract. Ecosystem shifts are often associated with multiple disturbances, but limited knowledge on the mechanisms involved hampers management. This study investigated how short-term shading affected the resilience of the seagrass Halophila ovalis to grazing by black swans (Cygnus atratus) -a historically dominant grazer currently recovering from hunting and habitat loss -in south-western Australian estuaries, using field surveys and a grazing-shading experiment. Black swans were heterogeneously distributed and, in a high-density site, consumed 23% of seagrass production. Seagrasses recovered rapidly from a single disturbance (i.e. short-term shading or grazing), even though shading alone halved carbohydrate content. When seagrasses were exposed to both disturbances, recovery depended on the type of grazing; where grazing was confined to leaves, leaf densities recovered within 3 weeks, but where grazing was on both leaves and rhizomes there was no recovery. Shading increased the frequency of apex initiation, as did rhizome grazing, but only if the plants had not been shaded. This indicates that shading alters the flow of energy needed to produce apices and leaves following disturbance on rhizomes. Based on the historical swan densities and continuing recurring phytoplankton blooms, management actions reintroducing swans without controlling algal blooms could have an on impact seagrass resilience and associated organisms.

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The importance of grazing intensity and frequency for physiological responses of the tropical seagrass Thalassia hemprichii

Cited by 21 publications

References 16 publications

Flooding effects on rapid responses of the invasive plant Alternanthera philoxeroides to defoliation

Flooding effects on rapid responses of the invasive plant Alternanthera philoxeroides to defoliation

The perverse fisheries consequences of mosquito net malaria prophylaxis in East Africa

Effects of multiple disturbances in seagrass meadows: shading decreases resilience to grazing

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