The Effect of Shading and Nutrient Addition on the Microphytobenthos, Macrofauna, and Biogeochemical Properties of Intertidal Flat Sediments

Tolhurst, T.J.; Chapman, M. G.; Murphy, Richard J.

doi:10.3389/fmars.2020.00419

Cited by 14 publications

(9 citation statements)

References 104 publications

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“…Benthic diatoms have evolved multiple adaptations to cope with the dynamic light conditions and the strong attenuation of incident light by the sediment 22 – 24 . Many benthic diatoms exhibit maximal growth rates at relatively low photon flux densities (PFD, in this manuscript often simply referred to as “light intensity”) below 50 µE m −2 s −1 , allowing them to thrive in shaded conditions 25 – 29 . In addition to physiological photoprotection, diatoms from the raphid pennate clade perform behavioural photoprotection by actively migrating through the sediment using their raphe, a longitudinal slit in the frustule equipped with an actin/myosin motility system 30 , 31 .…”

Section: Introductionmentioning

confidence: 99%

Light intensity and spectral composition drive reproductive success in the marine benthic diatom Seminavis robusta

Bilcke

Craenenbroeck

Castagna

et al. 2021

Sci Rep

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The properties of incident light play a crucial role in the mating process of diatoms, a group of ecologically important microalgae. While species-specific requirements for light intensity and photoperiod have been observed in several diatom species, little is known about the light spectrum that allows sexual reproduction. Here, we study the effects of spectral properties and light intensity on the initiation and progression of sexual reproduction in the model benthic diatom Seminavis robusta. We found that distinct stages of the mating process have different requirements for light. Vigorous mating pair formation occurred under a broad range of light intensities, ranging from 10 to 81 µE m−2 s−1, while gametogenesis and subsequent stages were strongly affected by moderate light intensities of 27 µE m−2 s−1 and up. In addition, light of blue or blue–green wavelengths was required for the formation of mating pairs. Combining flow cytometric analysis with expression profiling of the diatom-specific cyclin dsCyc2 suggests that progression through a blue light-dependent checkpoint in the G1 cell cycle phase is essential for induction of sexual reproduction. Taken together, we expand the current model of mating in benthic pennate diatoms, which relies on the interplay between light, cell cycle and sex pheromone signaling.

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Section: Introductionmentioning

confidence: 99%

Light intensity and spectral composition drive reproductive success in the marine benthic diatom Seminavis robusta

Bilcke

Craenenbroeck

Castagna

et al. 2021

Sci Rep

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“…Although we found most of the environmental parameters, we measured were relatively homogenous across the degradation gradient, shading, which obviously declined with a decrease in canopy cover, might have been a key factor responsible for the decline in faunal richness and diversity. Under shadier conditions, due to denser canopies, mangroves produce more leaf litter, cycles more nutrients and maintain higher soil moisture (Tolhurst et al 2020). Heavy shading can significantly modify processes and properties at the sediment-water interface, such as increased carbohydrate accumulation on the burrow surface, which may affect faunal abundance and distribution (Khon et al 2010;Tolhurst et al 2020), as was shown Similar patterns were also observed by Ruwa (1988), who found species diversity greater in moderate shade conditions.…”

Section: Discussionmentioning

confidence: 66%

“…Under shadier conditions, due to denser canopies, mangroves produce more leaf litter, cycles more nutrients and maintain higher soil moisture (Tolhurst et al 2020). Heavy shading can significantly modify processes and properties at the sediment-water interface, such as increased carbohydrate accumulation on the burrow surface, which may affect faunal abundance and distribution (Khon et al 2010;Tolhurst et al 2020), as was shown Similar patterns were also observed by Ruwa (1988), who found species diversity greater in moderate shade conditions.…”

Section: Discussionmentioning

confidence: 66%

Functional responses of mangrove fauna to forest degradation

et al. 2022

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Structural degradation of mangroves through the partial removal of trees is globally pervasive and likely to affect ecological functioning, including habitat provisioning for biodiversity. Biodiversity responses will depend on the severity of degradation, yet few studies have contraste and quantified several degradation states. Addressing this knowledge gap, we sampled faunal diversity across a range of mangrove forests in southern Kenya. Canopy cover was the strongest predictor of faunal responses among forest structural variables. Faunal abundance, species richness and biodiversity all decreased with reduction in canopy cover, and taxonomic and functional composition changed. The trophic diversity of crabs peaked at intermediate canopy cover, with degraded habitats having more generalist species and fewer specialists. Functional redundancy was unaffected by canopy thinning. The decline in functional diversity and richness of brachyuran crabs with canopy cover implies that resource-use efficiency weakens with increasing degradation. Our results are indicative of significant alterations to forest functioning with degradation, because epibenthic fauna are important regulators of mangrove ecosystem processes, including nutrient cycling and carbon.

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“…Examples include long-term moored vessels, docks, wharfs, jetties, and pontoon moorings. Light and shading are known to reduce photosynthesis, growth, and depth distribution of seagrasses [226,227], alter water column and benthic primary production, metabolism and nutrient dynamics [228,229] and benthic community structure and function [230,231]. Studies documenting the effects of shading by dock structures on seagrasses include those by Loflin [232] and Shafer [233].…”

Section: Light Conditionsmentioning

confidence: 99%

Boating- and Shipping-Related Environmental Impacts and Example Management Measures: A Review

Byrnes¹,

Dunn²

2020

JMSE

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Boating and shipping operations, their associated activities and supporting infrastructure present a potential for environmental impacts. Such impacts include physical changes to bottom substrate and habitats from sources such as anchoring and mooring and vessel groundings, alterations to the physico-chemical properties of the water column and aquatic biota through the application of antifouling paints, operational and accidental discharges (ballast and bilge water, hydrocarbons, garbage and sewage), fauna collisions, and various other disturbances. Various measures exist to sustainably manage these impacts. In addition to a review of associated boating- and shipping-related environmental impacts, this paper provides an outline of the government- and industry-related measures relevant to achieving positive outcomes in an Australian context. Historically, direct regulations have been used to cover various environmental impacts associated with commercial, industrial, and recreational boating and shipping operations (e.g., MARPOL). The effectiveness of this approach is the degree to which compliance can be effectively monitored and enforced. To be effective, environmental managers require a comprehensive understanding of the full range of instruments available, and the respective roles they play in helping achieve positive environmental outcomes, including the pros and cons of the various regulatory alternatives.

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The Effect of Shading and Nutrient Addition on the Microphytobenthos, Macrofauna, and Biogeochemical Properties of Intertidal Flat Sediments

Cited by 14 publications

References 104 publications

Light intensity and spectral composition drive reproductive success in the marine benthic diatom Seminavis robusta

Light intensity and spectral composition drive reproductive success in the marine benthic diatom Seminavis robusta

Functional responses of mangrove fauna to forest degradation

Boating- and Shipping-Related Environmental Impacts and Example Management Measures: A Review

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