Environmental Drivers of Seagrass-Associated Nekton Abundance Across the Northern Gulf of Mexico

Belgrad, Benjamin A.; Correia, Kelly M.; Darnell, Kelly M.; Darnell, M. Zachary; Hayes, Christian; Hall, Margaret O.; Furman, Bradley T.; Martin, Charles W.; Smee, Delbert L.

doi:10.1007/s12237-021-00927-0

Cited by 11 publications

(6 citation statements)

References 48 publications

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“…In the species richness SEM, depth had a direct negative effect on species richness, indicating a greater diversity of fishes at shallower sites. This could be due to correlations between depth and unmeasured characteristics of the meadow, such as meadow area, patchiness, or shoot density (Aoki et al., 2020a; Belgrad et al., 2021). For example, in the shallower and more frequently flushed South Bay meadow, average seagrass shoot densities were 4.4 times greater than in Hog Island Bay during the study period (365 vs. 84 shoots/m 2 ) (McGlathery 2017; Aoki et al., 2020a) (Appendix S6).…”

Section: Discussionmentioning

confidence: 99%

Effects of seagrass restoration on coastal fish abundance and diversity

Hardison

McGlathery

Castorani

2023

Conservation Biology

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Restoration is accelerating to reverse global declines of key habitats and recover lost ecosystem functions, particularly in coastal ecosystems. However, there is high uncertainty about the long‐term capacity of restored ecosystems to provide habitat and increase biodiversity, and the degree to which these ecosystem services are mediated by spatial and temporal environmental variability. We addressed these gaps by sampling fishes biannually for 5–7 years (2012–2018) at 16 sites inside and outside of a rapidly‐expanding restored seagrass meadow in coastal Virginia, USA. Despite substantial among‐year variation in abundance and species composition, seine catches in restored seagrass beds were consistently more numerous (6.4× more fish, P < 0.001) and speciose (2.6× greater species richness, P < 0.001; 3.1× greater Hill‐Shannon diversity, P = 0.03) than adjacent unvegetated areas, with larger catches particularly during summer (vs. autumn, P < 0.01). Structural equation modeling revealed that depth and water residence time interacted to control seagrass presence, leading to higher fish abundance and richness in shallow, well‐flushed areas that supported seagrass. Together, our results indicate that seagrass restoration yields large and consistent benefits for many coastal fishes, but that restoration and its benefits are sensitive to the dynamic seascapes within which it is established. Consideration of how seascape‐scale environmental variability impacts both the success of habitat restoration as well as subsequent ecosystem function will improve restoration outcomes and the provisioning of ecosystem services.This article is protected by copyright. All rights reserved

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Section: Discussionmentioning

confidence: 99%

Effects of seagrass restoration on coastal fish abundance and diversity

Hardison

McGlathery

Castorani

2023

Conservation Biology

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“…Prior to blue crab tethering, seagrass structural complexity was measured near each tethering pole (6-12 measurements per station). Percent cover of seagrass by species and bare sediment were quantified in 1-m 2 PVC quadrats sectioned into 10-cm x 10-cm squares placed near the tethering area following methods from Belgrad et al (2021). The presence of drift and attached macroalgae was also noted within each quadrat.…”

Section: Predation Experimentsmentioning

confidence: 99%

Regional variation in seagrass complexity drives blue crab Callinectes sapidus mortality and growth across the northern Gulf of Mexico

Hayes

Alford

Belgrad

et al. 2022

Mar. Ecol. Prog. Ser.

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Seagrass meadows provide greater predator refuge and resource availability than unvegetated habitats and generally improve the survival and growth rates of associated animals. Few studies, however, have examined how these relationships might vary at a region-wide spatial scale. The blue crab Callinectes sapidus is a commercially important species that uses turtlegrass Thalassia testudinum habitats, but it is unclear if blue crab use of seagrass habitats varies across the northern Gulf of Mexico (GOM), USA. We conducted synoptic predation and growth experiments at 6 turtlegrass-dominated estuaries in the northern GOM to evaluate the role of seagrass structural complexity on juvenile (9.7-44 mm carapace width) blue crab mortality due to predation and growth. Relationships of blue crab predation and growth rate with seagrass shoot density, canopy height, temperature, and seagrass leaf area index (LAI) were evaluated using linear and generalized linear mixed effects models. Mortality rates due to predation (50 ± 9.6% [mean ± SD] crabs eaten, n = 286) showed negative relationships with LAI across the northern GOM. Conversely, mean crab growth rate (0.513 ± 0.317 mm d-1) varied across the northern GOM but was independent of seagrass shoot density or canopy height. We found that: (1) turtlegrass-dominated beds with a greater seagrass LAI provided more effective cover for juvenile blue crabs across the northern GOM, (2) blue crabs across multiple GOM estuaries responded similarly to changes in LAI, and (3) blue crab growth varied across the northern GOM and was likely dependent on regional factors unrelated to structural complexity. This study illustrates the value of conducting synchronous field-based experiments across broad spatial scales to identify regional patterns and the influence of regional versus local drivers.

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“…Sites were selected by overlaying a tessellated hexagonal grid (500 m edge length) on each estuary in ArcGIS (Moore, 2009;Neckles et al, 2012;Wilson and Dunton, 2012). One station was randomly generated within each of the 20-25 grid cells that contained more than 50% seagrass coverage, with a minimum of 500 m distance between sites (Belgrad et al, 2021). Across all regions, turtle grass (T. testudinum) was the dominant macrophyte taxa; however, manatee grass (Syringodium filiforme) and shoal grass (Halodule wrightii) were also common.…”

Section: Study Regionsmentioning

confidence: 99%

“…At each sampling site, abiotic conditions (i.e., temperature, salinity, dissolved oxygen, and depth) were recorded, drift macroalgal biomass was measured, and seagrass cover/abundance and morphometrics [i.e., percent cover (0-100%), shoot height (mm), and shoot density] were assessed. Because we sampled synoptically using the same methods, we were able to evaluate algal biomass and distribution within and among locations across the northern Gulf of Mexico (Supplementary Table S1; Belgrad et al, 2021;Correia, 2021).…”

Section: Study Regionsmentioning

confidence: 99%

Drift macroalgae positively influence seagrass-associated nekton communities of the northern Gulf of Mexico

Correia

Alford

Belgrad

et al. 2022

Front. Environ. Sci.

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Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can provide additional food resources and habitat complexity, leading to increased animal abundance, but large concentrations can also inhibit faunal movements, smother benthic communities, and contribute to hypoxia, reducing nekton abundance. Despite its ubiquity, few studies have quantified drift macroalgal prevalence over large spatial scales or its effects on seagrass-associated nekton, hindering our understanding of the functional role of drift macroalgae in ecosystems. We quantified the relationship between drift macroalgal biomass and the seagrass-associated nekton community within five estuaries spanning 2000 km across the northern Gulf of Mexico. Overall, increases in macroalgal biomass within seagrass meadows significantly influenced community structure, increasing shrimp, crab, and fish abundances, but the effect varied by region. Relationships between species richness, diversity, organism size, and macroalgal biomass were not observed, suggesting that drift macroalgae provide additional habitat but not necessarily new niche space. Small nekton play a vital role in many local fisheries, providing valuable food resources for fish and invertebrates. Increased recruitment into macroalgae can benefit local fisheries by providing shelter and increased food resources, which may increase the survival, growth, and population size of recreationally and economically important species. While excess levels of drift macroalgae can negatively impact benthic plant and animal communities, particularly in eutrophic areas, the moderate levels observed during this survey were associated with positive effects on organismal abundance, suggesting that drift algal dynamics should be considered in habitat-based management strategies for coastal estuaries.

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Environmental Drivers of Seagrass-Associated Nekton Abundance Across the Northern Gulf of Mexico

Cited by 11 publications

References 48 publications

Effects of seagrass restoration on coastal fish abundance and diversity

Effects of seagrass restoration on coastal fish abundance and diversity

Regional variation in seagrass complexity drives blue crab Callinectes sapidus mortality and growth across the northern Gulf of Mexico

Drift macroalgae positively influence seagrass-associated nekton communities of the northern Gulf of Mexico

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