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Biogeochemical Consequences of Graci...

Toothman, Byron R., III,

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Biogeochemical Consequences of Gracilaria vermiculophylla Invasion: Impacts on Mercury Cycling and Consumer Uptake /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Biogeochemical Consequences of Gracilaria vermiculophylla Invasion: Impacts on Mercury Cycling and Consumer Uptake // Byron R Toothman III.
Author:	Toothman, Byron R., III,
Description:	1 electronic resource (158 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 86-04, Section: B.
Contained By:	Dissertations Abstracts International86-04B.
Subject:	Biogeochemistry. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31484359
ISBN:	9798384476528

Biogeochemical Consequences of Gracilaria vermiculophylla Invasion: Impacts on Mercury Cycling and Consumer Uptake /
Toothman, Byron R., III,

Biogeochemical Consequences of Gracilaria vermiculophylla Invasion: Impacts on Mercury Cycling and Consumer Uptake /Byron R Toothman III. - 1 electronic resource (158 pages)

Source: Dissertations Abstracts International, Volume: 86-04, Section: B.

As the transition between surface waters and seawater, estuaries are a catchment and center for mercury (Hg) transformation to neurotoxic intermediates such as methylmercury (MeHg). Contemporary sources of mercury continually contribute to legacy sources in the biosphere. Estuarine waters are also an essential natural resource and the majority of commercially important food fish rely on them for some portion of their life cycle. Nuisance macroalgal blooms of Gracilaria vermiculophylla (Gracilaria) contribute to stratification, hypoxia, and support microbial communities responsible for Hg cycling. Here we hypothesize that the enhancement of Hg by Gracilaria mats increases the exposure of estuarine consumers and food webs to intermediates such as methylmercury (MeHg).This work takes a two-phase approach to determine if Gracilaria mats impact invertebrate assimilation of Hg: 1) Investigating algal mat impacts on mercury uptake as total mercury (THg) by Ilyanassa obsoleta in two southeastern North Carolina estuaries, and Great Bay, New Hampshire, and 2) an analysis of THg and MeHg concentrations in invertebrates with differing mobility and feeding strategies: Crassostrea virginica (oyster), juvenile penaeid shrimp (shrimp), and the eastern mudsnail, Ilyanassa obsoleta (mudsnail). Analysis of δ 15N and δ 13C is used to infer relative trophic level and carbon sources of the invertebrates.Spatial sampling revealed that mean THg concentrations in mudsnails collected from Gracilaria mats (1.32 μg/g) were more than twice that of those collected from unvegetated mudflat in North Carolina (p < 0.001) and exceeded the U.S. FDA standard for human consumption. Similar significant increases were observed (>60%) in Great Bay (p < 0.001). Gracilaria cover is a good predictor of THg (linear regression, p < 0.001) from both regions as well. Comparisons of invertebrate THg and MeHg indicate a more complex story and δ 13C and δ 15N analysis suggests that mobility and feeding strategies appear to impact uptake and assimilation. Association with algal mats resulted in significantly higher (p< 0.007) THg and MeHg in oysters and shrimp, and only THg in mudsnails. Mudsnails contained comparatively little MeHg and much higher THg than the other invertebrates resulting in extremely low THg:MeHg. Increased concentrations of Hg species in consumers collected from mats confirm our hypotheses. However, increases in methylation potential within algal mats cannot sufficiently explain the side-by-side comparisons of THg and MeHg in the invertebrates, considering the large discrepancy between THg and MeHg in mudsnails. This warrants additional investigation considering the likelihood that these effects are likely to occur in blooms of any macroalga in any location and impacting human health.

English

ISBN: 9798384476528Subjects--Topical Terms:

545717
Biogeochemistry.
Subjects--Index Terms:

Ecosystem engineer

Biogeochemical Consequences of Gracilaria vermiculophylla Invasion: Impacts on Mercury Cycling and Consumer Uptake /
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502 $b Ph.D. $c The University of North Carolina at Wilmington $d 2024.
520 $a As the transition between surface waters and seawater, estuaries are a catchment and center for mercury (Hg) transformation to neurotoxic intermediates such as methylmercury (MeHg). Contemporary sources of mercury continually contribute to legacy sources in the biosphere. Estuarine waters are also an essential natural resource and the majority of commercially important food fish rely on them for some portion of their life cycle. Nuisance macroalgal blooms of Gracilaria vermiculophylla (Gracilaria) contribute to stratification, hypoxia, and support microbial communities responsible for Hg cycling. Here we hypothesize that the enhancement of Hg by Gracilaria mats increases the exposure of estuarine consumers and food webs to intermediates such as methylmercury (MeHg).This work takes a two-phase approach to determine if Gracilaria mats impact invertebrate assimilation of Hg: 1) Investigating algal mat impacts on mercury uptake as total mercury (THg) by Ilyanassa obsoleta in two southeastern North Carolina estuaries, and Great Bay, New Hampshire, and 2) an analysis of THg and MeHg concentrations in invertebrates with differing mobility and feeding strategies: Crassostrea virginica (oyster), juvenile penaeid shrimp (shrimp), and the eastern mudsnail, Ilyanassa obsoleta (mudsnail). Analysis of δ 15N and δ 13C is used to infer relative trophic level and carbon sources of the invertebrates.Spatial sampling revealed that mean THg concentrations in mudsnails collected from Gracilaria mats (1.32 μg/g) were more than twice that of those collected from unvegetated mudflat in North Carolina (p < 0.001) and exceeded the U.S. FDA standard for human consumption. Similar significant increases were observed (>60%) in Great Bay (p < 0.001). Gracilaria cover is a good predictor of THg (linear regression, p < 0.001) from both regions as well. Comparisons of invertebrate THg and MeHg indicate a more complex story and δ 13C and δ 15N analysis suggests that mobility and feeding strategies appear to impact uptake and assimilation. Association with algal mats resulted in significantly higher (p< 0.007) THg and MeHg in oysters and shrimp, and only THg in mudsnails. Mudsnails contained comparatively little MeHg and much higher THg than the other invertebrates resulting in extremely low THg:MeHg. Increased concentrations of Hg species in consumers collected from mats confirm our hypotheses. However, increases in methylation potential within algal mats cannot sufficiently explain the side-by-side comparisons of THg and MeHg in the invertebrates, considering the large discrepancy between THg and MeHg in mudsnails. This warrants additional investigation considering the likelihood that these effects are likely to occur in blooms of any macroalga in any location and impacting human health.
546 $a English
590 $a School code: 1537
650 4 $a Biogeochemistry. $3 545717
650 4 $a Biological oceanography. $3 2122748
650 4 $a Microbiology. $3 536250
650 4 $a Biology. $3 522710
653 $a Ecosystem engineer
653 $a Estuaries
653 $a Gracilaria vermiculophylla
653 $a Invasive species
653 $a Mercury
690 $a 0425
690 $a 0416
690 $a 0410
690 $a 0306
710 2 $a The University of North Carolina at Wilmington. $b Biology and Marine Biology. $e degree granting institution. $3 3816917
720 1 $a Cahoon, Lawrence B. $e degree supervisor.
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791 $a Ph.D.
792 $a 2024
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31484359