The thin(ning) green line? Investigating changes in Kenya's seagrass coverage

Harcourt, William D.; Briers, Robert A.; Huxham, Mark

doi:10.1098/rsbl.2018.0227

Cited by 27 publications

(36 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Seagrass is a globally threatened habitat. Across the Kenyan coast, total coverage of seagrass is declining at 1.59% yr −1 , and in Gazi losses are faster at 1.68% yr −1 ; decline here is likely to be caused mostly by small-scale but persistent damage from fishing activities (Harcourt et al, 2018). There are many reasons for concern about these losses, since they may undermine the livelihoods of local fishers, enhance erosion and diminish the natural beauty of these coasts.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Seagrass Removal Leads to Rapid Changes in Fauna and Loss of Carbon

et al. 2019

Self Cite

View full text Add to dashboard Cite

Seagrass habitats are important natural carbon sinks, with an average of ∼14 kg C m −2 buried in their sediments. The fate of this carbon following seagrass removal or damage has major environmental implications but is poorly understood. Using a removal experiment lasting 18 months at Gazi Bay, Kenya, we investigated the impacts of seagrass loss on sediment topography, hydrodynamics, faunal community structure and carbon dynamics. Sediment pins were used to monitor surface elevation. The effects of seagrass removal on water velocity was investigated using Plaster of Paris dissolution. Sediment carbon concentration was measured at the surface and down to 50 cm. Rates of litter decay at three depths in harvested and control treatments were measured using litter bags. Drop samples, cores, and visual counts of faunal mounds and burrows were used to monitor the impact of seagrass removal on the epifaunal and infaunal communities. Whilst control plots showed sediment elevation, harvested plots were eroded (7.6 ± 0.4 and −15.8 ± 0.5 mm yr −1 respectively, mean ± 95% CI). Carbon concentration in the surface sediments was significantly reduced with a mean carbon loss of 2.21 Mg C ha −1 in the top 5 cm. Because sediment was lost from harvested plots, with a mean difference in elevation of 3 cm, an additional carbon loss of up to 2.54 Mg C ha −1 may have occurred over the 18 months. Seagrass removal had rapid and dramatic impacts on infauna and epifauna. There was a loss of diversity in harvested plots and a shift toward larger bodied, bioturbating species, with a significant increase in mounds and burrows. Buried seagrass litter decomposed significantly faster in the harvested compared with the control plots. Loss of seagrass therefore led to rapid changes in sediment dynamics and chemistry driven in part by significant alterations in the faunal community.

show abstract

Section: Discussionmentioning

confidence: 99%

“…den Hartog, and Thalassia hemprichii (Enhrenberg) Aschers. These occur either as monospecific stands or mixed with other seagrass species with their coverage extending from low intertidal to 7 or 8 m depth below chart datum (Harcourt et al, 2018). The other six species are: Halodule uninervis (Forssk.)…”

Section: Study Sitementioning

confidence: 99%

Seagrass Removal Leads to Rapid Changes in Fauna and Loss of Carbon

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…This study, to the best of our knowledge, is one of the first to systematically estimate the current and historic extent of seagrasses in any country and place it in the context of associated ecosystem services (see also, Ruiz et al, 2015 ; Harcourt et al, 2018 ). With high certainty, at least 44% of United Kingdom’s seagrasses has been lost since 1936.…”

Section: Discussionmentioning

confidence: 99%

Historical Analysis Exposes Catastrophic Seagrass Loss for the United Kingdom

et al. 2021

View full text Add to dashboard Cite

The spatial extent of seagrass is poorly mapped, and knowledge of historical loss is limited. Here, we collated empirical and qualitative data using systematic review methods to provide unique analysis on seagrass occurrence and loss in the United Kingdom. We document 8,493 ha of recently mapped seagrass in the United Kingdom since 1998. This equates to an estimated 0.9 Mt of carbon, which, in the current carbon market represents about £22 million. Using simple models to estimate seagrass declines triangulated against habitat suitability models, we provide evidence of catastrophic seagrass loss; at least 44% of United Kingdom’s seagrasses have been lost since 1936, 39% since the 1980’s. However, losses over longer time spans may be as high as 92%. Based on these estimates, historical seagrass meadows could have stored 11.5 Mt of carbon and supported approximately 400 million fish. Our results demonstrate the vast scale of losses and highlight the opportunities to restore seagrass to support a range of ecosystems services.

show abstract

“…This study was done in parallel to the work described in Githaiga et al (2019). The intertidal seagrass meadows in Gazi Bay are intensively used for artisanal fishing activities (Harcourt et al 2018) and the Bay is home to one of the major fish landing sites in South East Kenya (FAO 2015). These activities resulted in visible scars within the seagrass meadows and are thought to have contributed to the decline of ~2% yr -1 in seagrass coverage between 2000 and 2016 (Harcourt et al 2018).…”

Section: Introductionmentioning

confidence: 99%

“…The intertidal seagrass meadows in Gazi Bay are intensively used for artisanal fishing activities (Harcourt et al 2018) and the Bay is home to one of the major fish landing sites in South East Kenya (FAO 2015). These activities resulted in visible scars within the seagrass meadows and are thought to have contributed to the decline of ~2% yr -1 in seagrass coverage between 2000 and 2016 (Harcourt et al 2018). The overall aim of this study was to identify impact pathways of seagrass perturbation by investigating changes in infauna and epifauna abundance as well as overall fauna community structure, resulting from seagrass removal.…”

Section: Introductionmentioning

confidence: 99%

Experimental harvest in a tropical seagrass meadow leads to shift in associated benthic communities

Cadier

Frouws

2019

Community Ecology

View full text Add to dashboard Cite

Seagrass meadows represent key ecosystems in coastal areas worldwide, hosting a great biodiversity of associated communities and thereby providing a large range of ecosystem services. In this study we present an experimental approach to investigate the effects of seagrass losses on related macrofauna assemblages. Over a three year period, seagrass canopies were removed in experimental plots and changes in epifauna, infauna and respective functional groups were recorded. The experimental removal of seagrass leaves resulted in a decline of 74% of overall macrofaunal abundance and the loss of several taxa. The immediate response of associated communities was followed by the establishment of an alternative assemblage, characterized by an increased number of bioturbators and deposit feeders. The colonization of disturbed seagrass plots by burrowing shrimps (Callianassidae) might have hindered the reestablishment of seagrass after the removal. Our findings highlight the important role of seagrasses as habitat forming species that provide relevant functioning and services in coastal ecosystems.

show abstract

The thin(ning) green line? Investigating changes in Kenya's seagrass coverage

Cited by 27 publications

References 14 publications

Seagrass Removal Leads to Rapid Changes in Fauna and Loss of Carbon

Seagrass Removal Leads to Rapid Changes in Fauna and Loss of Carbon

Historical Analysis Exposes Catastrophic Seagrass Loss for the United Kingdom

Experimental harvest in a tropical seagrass meadow leads to shift in associated benthic communities

Contact Info

Product

Resources

About