Effects of intertidal seagrass habitat fragmentation on turbulent diffusion and retention time of solutes

Lara, Maria Aparecida Cassiano; Peralta, Gloria; Alonso, J.J. Jose; Morris, Edward P.; González-Ortiz, Vanessa; Rueda-Márquez, J.J.; Pérez‐Lloréns, José Lucas

doi:10.1016/j.marpolbul.2012.07.044

Cited by 18 publications

(11 citation statements)

References 51 publications

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“…The nutrients in small patches may be flushed out of the patch due to the increased mixing between the patch and the nearby gap. This predicted increase in the mixing level in fragmented canopies also supports the observed increased diffusion coefficient in fragmented canopies under unidirectional flows [ 44 ]. Modifications in the mixing and turbulent processes in gapped canopies may also result in changes in the water turbidity, which in turn may reduce light intensity and the consequent loss of seagrass areas [ 45 ].…”

Section: Discussionsupporting

confidence: 73%

Interactions between Fragmented Seagrass Canopies and the Local Hydrodynamics

et al. 2016

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The systematic creation of gaps within canopies results in fragmentation and the architecture of fragmented canopies differs substantially from non-fragmented canopies. Canopy fragmentation leads to spatial heterogeneity in hydrodynamics and therefore heterogeneity in the sheltering of canopy communities. Identifying the level of instability due to canopy fragmentation is important for canopies in coastal areas impacted by human activities and indeed, climate change. The gap orientation relative to the wave direction is expected to play an important role in determining wave attenuation and sheltering. Initially we investigated the effect of a single transversal gap within a canopy (i.e. a gap oriented perpendicular to the wave direction) on hydrodynamics, which was compared to fully vegetated canopies (i.e. no gaps) and also to bare sediment. The wave velocity increased with gap width for the two canopy densities studied (2.5% and 10% solid plant fraction) reaching wave velocities found over bare sediments. The turbulent kinetic energy (TKE) within the gap also increased, but was more attenuated by the adjacent vegetation than the wave velocity. As expected, denser canopies produced a greater attenuation of both the wave velocity and the turbulent kinetic energy within an adjacent gap, compared to sparse canopies. Using non-dimensional analysis and our experimental data, a parameterization for predicting TKE in a canopy gap was formulated, as a function of easily measured variables. Based on the experimental results, a fragmented canopy model was then developed to determine the overall mixing level in such canopies. The model revealed that canopies with large gaps present more mixing than canopies with small gaps despite having the same total gap area in the canopy. Furthermore, for the same total gap area, dense fragmented canopies provide more shelter than sparse fragmented canopies.

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Section: Discussionsupporting

confidence: 73%

Interactions between Fragmented Seagrass Canopies and the Local Hydrodynamics

et al. 2016

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“…These can vary by an order of magnitude across fragmented canopies because of the great difference in flow speed between canopy throughflow, and flow over and around patches (Lightbody et al, 2008). This can affect the canopies themselves, for example by varying their exposure to pollution or their access to dissolved nutrients and gasses (Lara et al, 2012).…”

Section: Consequences Of Patch-scale Interactions At Landscape-scalementioning

confidence: 99%

Biophysical Interactions in Fragmented Marine Canopies: Fundamental Processes, Consequences, and Upscaling

Folkard

2019

Front. Mar. Sci.

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Spatial fragmentation is a near-ubiquitous characteristic of marine canopies. Biophysical interactions with fragmented canopies are multi-faceted and have many significant implications at multiple scales. The aims of this paper are to review research on biophysical interactions in fragmented marine canopies, identify current gaps in knowledge and understanding, and propose ways forward. The review starts at the patch/gap scale and focuses initially on hydrodynamic interactions. It then considers the consequences of these interactions for particulate and dissolved material, and distributions of canopy-associated organisms. Finally, it addresses issues of upscaling to landscape-scale and ways in which this research can be applied to marine landscape management. Work on a broad range of canopy types is considered, including micro-algal biofilms and turf algae; macro-algae, seagrasses and coral reefs; saltmarsh vegetation and mangroves. Although the focus is on marine canopies, insights from studies of fragmented canopies in other contexts are drawn on where relevant. These include freshwater environments and terrestrial forests, grasslands, crop canopies, and urban areas. Specific areas requiring greater attention are highlighted. As a result of this meta-analysis, the following recommendations are made for further research. A lack of basic data is identified across all canopy types regarding the formation, fate and spatial and temporal characteristics of canopy patches, gaps, and spatial structure. Studies of hydrodynamics with fragmented canopies would benefit from shifting focus toward more non-uniform, realistic configurations, while ecological research in this area would benefit from a move toward configurations that are more controlled and tractable for quantitative modeling. More comparative studies across canopy types would enable understanding of their biophysical interactions and their consequences to be more fully tested and developed. A greater incorporation of chemical aspects of canopy systems into work that has hitherto focused on biophysical interactions would also be pertinent. Upscaling of patch and gap-scale phenomena to landscape-scale is identified as a crucial topic, since it is at the latter scale that management efforts are most readily carried out. Overall, an approach that balances hydrodynamics, marine canopy ecology, spatial analysis of landscapes, biogeochemistry, and socio-environmental interactions is recommended.

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“…Distributional and structural patterns of C. nodosa meadows depend on various environmental factors that characterize the coastline such as substrate, depth, slope, lighting and salinity (Barberá et al, 2005;Barquín-Diez et al, 2005;Reyes et al, 1995). However, coastal hydrodynamics may be the driving force that controls the upper limit distribution of C. nodosa, as found in the case of Z. noltei (Lara et al, 2012). Herein, we report on the rare but consistent presence of the common seagrass C. nodosa in several semi-exposed and sheltered intertidal rocky pools of Fuerteventura (Canary Islands) throughout a six-year period.…”

Section: Introductionmentioning

confidence: 99%

“…While Z. marina and Z. noltei are temperate species widely distributed along the European Atlantic and Mediterranean coastlines, C. nodosa is a tropical seagrass present throughout the Mediterranean sea, the Macaronesian archipelagos of Madeira and the Canary Islands, the Mauritania region, and the Algarve coastline, where it occurs intermixed with temperate seagrasses (Cacabelos et al, 2015;Hemminga & Duarte, 2000;Short et al, 2007). Although C. nodosa can be present in intertidal zones such as sheltered bays (Bay of Cádiz; de los Santos, Brun, Vergara, & Pérez-Lloréns, 2013;Lara et al, 2012) or coastal lagoons (Ria Formosa; Silva & Santos, 2003), its distribution is mostly restricted to the subtidal or lower intertidal zones, and always associated with sandy substrates. In the particular case of the Bay of Cadiz, C. nodosa is also present in one exposed site facing the open ocean, forming small-scattered patches in intertidal pools with sandy accumulations (de los Santos et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The underreported presence of the subtidal seagrass Cymodocea nodosa in rocky intertidal pools of the Canary Islands

González-Lorenzo

Toledo-Guedes

Rodríguez-Riesco

et al. 2020

Marine Biology Research

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During 2014, 21 patches of Cymodocea nodosa were found in intertidal pools in Fuerteventura (Canary Islands). Pool substratum was mixed sand and rock, but mostly dominated by stone bottoms. Most plants were established with fully exposed rhizomes, filling small fissures without sediment. During subsequent sampling surveys between 2016 and 2019, the presence of these patches was consistent over time in an environment normally considered extreme for most seagrasses. As far as we know, the presence of various intertidal areas with Cymodocea nodosa patches has not been observed previously in the Canary Islands. If the presence of C. nodosa patches in these intertidal pools is stable over time, it raises new environmental management and conservation questions for this endangered species in the Canary Islands. In addition, due to the current regression of C. nodosa meadows, our observations represent an optimistic perspective that underline the need for specific monitoring plans for this ecosystem.

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Effects of intertidal seagrass habitat fragmentation on turbulent diffusion and retention time of solutes

Cited by 18 publications

References 51 publications

Interactions between Fragmented Seagrass Canopies and the Local Hydrodynamics

Interactions between Fragmented Seagrass Canopies and the Local Hydrodynamics

Biophysical Interactions in Fragmented Marine Canopies: Fundamental Processes, Consequences, and Upscaling

The underreported presence of the subtidal seagrass Cymodocea nodosa in rocky intertidal pools of the Canary Islands

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