Nutrient load and epiphytes are drivers of increased herbivory in seagrass communities

Jiménez–Ramos, Rocío; Egea, L.; Vergara, Juan J.; Brun, Fernando G.

doi:10.3354/meps12622

Cited by 13 publications

(10 citation statements)

References 101 publications

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“…Earlier studies have revealed that a large number of seagrass-associated organisms feed heavily on marine epiphytic algae, which are important primary producers in seagrass ecosystems and make a significant contribution to food webs (Borowitzka et al 2006, Myers andHeck 2013). Moreover, previous works have demonstrated that the presence of different species of epiphytes in seagrass leaves increases the consumption in these ecosystems by different consumers, such as sea urchins, fishes and mesograzers (Garcia et al 1999, Jaschinski and Sommer 2008a, Marco-Méndez et al 2015, Jiménez-Ramos et al 2018a. Overproduction by epiphytic algae, however, has been associated with large-scale losses of seagrasses in eutrophic waters (Silberstein et al 1986, Walker andMcComb 1992).…”

Section: Introductionmentioning

confidence: 99%

The role of flow velocity combined with habitat complexity as a top–down regulator in seagrass meadows

Jiménez–Ramos

Egea

Vergara

et al. 2018

Oikos

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Large‐scale losses of seagrass areas have been associated with eutrophication events, which have led to an overproduction of photosynthetic organisms including epiphytes. Grazers that feed on epiphytes can exert a significant top–down control in the system, but the effects of physical factors on grazing activity and feeding behaviour have been rarely examined. We addressed the combination of hydrodynamic regime and seagrass shoot density can alter the feeding and foraging behaviours of mesograzers. A full factorial experiment, with flow velocity (high, medium and low) and shoot density (high versus low) as main factors, was conducted in a racetrack flume using artificial seagrass plots. The results showed that when high flow velocity conditions were combined with low shoot density, consumption of epiphytes by mesograzers was strongly reduced. In contrast, when flow velocity was low or shoot density was high, mesograzers exhibited high feeding rates and vigorous swimming behaviour. These results clearly indicate that hydrodynamic stress reduces the time that mesograzers can spend feeding, since it inhibits their swimming behaviour, and thus indirectly affecting to the density of epiphytes. Therefore, the triggering of trophic cascade effects in seagrass communities under these experimental conditions depended on the interrelationship and feedbacks among shoot density, abiotic (flow velocity) and biotic (epiphytes and mesograzers) compartments, with flow velocity exerting a top–down control on seagrass ecosystems.

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Section: Introductionmentioning

confidence: 99%

The role of flow velocity combined with habitat complexity as a top–down regulator in seagrass meadows

Jiménez–Ramos

Egea

Vergara

et al. 2018

Oikos

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“…Direct consumption of epiphytes attached to seagrass leaves is usually by mesograzers and can have positive consequences on leaf growth and indirectly, for herbivores that consume seagrass (Borowitzka et al 2006). On the other hand, the removal of epiphytes might also negatively affect herbivores such as fish or sea urchins, many of which gain nutrition from the epiphytic algae, in addition to seagrass itself (Marco‐Méndez et al 2017) or could be also attracted by them (Jiménez‐Ramos et al 2018 b ).…”

Section: Discussionmentioning

confidence: 99%

“…Care was taken to collect shoots with intact vertical rhizomes to minimize changes in leaf properties and in order to allow the safeguarding of leaves throughout the experiment. Once transported to the laboratory and prior to any measurement, 40 healthy shoots (no necrosis or bites) from each location were carefully selected and epiphytes were carefully scraped off to avoid their potentially confounding role in feeding preference (Jiménez‐Ramos et al 2018 b ).…”

Section: Methodsmentioning

confidence: 99%

Factors modulating herbivory patterns in Cymodocea nodosa meadows

Jiménez–Ramos

Egea

Vergara

et al. 2021

Limnology & Oceanography

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In coastal marine food webs, seagrass‐grazer interactions play a fundamental role in ecological processes by regulating the structure and functioning of plant communities. Therefore, assessing the strength of these seagrass‐grazer links and identifying the mechanisms that regulate these relationships are crucial to increasing our understanding of community and ecosystem structure and dynamics. Herbivory on the temperate seagrass Cymodocea nodosa was evaluated in four locations with contrasting abiotic and biotic factors (i.e., depth; meadow size; seagrass shoot density, productivity, and leaf traits; and herbivore presence) using cross‐transplantation experiments carried out once per season to account for seasonal variation. Patterns of feeding rates on C. nodosa meadows showed high temporal variability, with peaks occurring in spring and summer. Results indicate that between 46.59% and 74.08% of the annual leaf production is lost to herbivory at the locations sampled in this study. Herbivory rates increased with higher nitrogen content and shoot density for all types of consumers (mesograzers, fishes, and sea urchins). This work highlights the need to integrate the abiotic and biotic factors modulating herbivory patterns, particularly in a foundation species like C. nodosa, for which changes in plant traits and grazer abundance may trigger trophic cascades with far‐reaching consequences for associated species.

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“…al, 2020). Limited studies exist on dugong feeding biology from India (D'Souza et al, 2015;Nair & Mohan, 1975) given the difficulty to observe them in the wild. Thus, stranded dugongs provide an opportunity to understand their dietary composition through gut sampling.…”

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confidence: 99%

“…Since availability of seagrasses is a limiting factor, understanding foraging patterns of dugongs is crucial in mapping their distribution. So far, dugong foraging preferences are known through direct observations of feeding or by analysis of stomach contents (Preen, 1992;Andre et al, 2005; De longh et al, 2007;D'souza et al, 2015). Data available from stomach content analysis has provided most detailed information on feeding habits of dugongs (Preen, 1995) and their energy requirements (Andre et al, 2005).Indian dugong populations are imperilled due to various threats with an estimated population of less than 300 individuals left in the wild (Pandey et al, 2010;Sivakumar & Nair, 2013).…”

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confidence: 99%

Opportunistic gut sampling indicates differential diet and plastic ingestion risk in Indian dugongs

Prajapati

Ghanekar

Pathan

et al. 2021

Preprint

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Dugongs, exclusively seagrass foragers, are globally threatened marine mammals. Knowledge on their feeding biology has been derived from few direct observations and mostly by analysis of stomach contents. Given limitations in data from Indian populations, dugong strandings serve as an opportunity to understand their dietary composition through gut sampling. In this paper, we utilize the gut contents collected from stranded dugongs to detect differences in the seagrass foraging between two isolated pockets of dugong distribution (Tamil Nadu and Gujarat) and supplement existing knowledge on dugong feeding biology in Indian waters. We extracted, enumerated and identified seagrass species from dugong gut contents. The proportion of seagrass leaf fragments were found higher (>40%) than other fragments in all the gut samples analysed. We recorded two seagrass genera (Halophila spp. and Halodule spp.) from Gujarat and five seagrass genera (Halophila spp., Halodule spp., Cymodocea spp., Enhalus spp., Syringodium spp.) from Tamil Nadu dugong individuals. We also obtained anthropogenic debris such as plastic, fishing net and wood fragments from the gut samples. We suggest enhanced monitoring of seagrass habitats and fine spatial scale threat mapping in entire dugong distribution range in India.

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Nutrient load and epiphytes are drivers of increased herbivory in seagrass communities

Cited by 13 publications

References 101 publications

The role of flow velocity combined with habitat complexity as a top–down regulator in seagrass meadows

The role of flow velocity combined with habitat complexity as a top–down regulator in seagrass meadows

Factors modulating herbivory patterns in Cymodocea nodosa meadows

Opportunistic gut sampling indicates differential diet and plastic ingestion risk in Indian dugongs

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