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European Journal of Applied Sciences – Vol. 12, No. 5

Publication Date: October 25, 2024

DOI:10.14738/aivp.125.17339.

Dasat, G. S., Christopher, F., Tim, J., & Dunn, C. (2024). Examining Microbial Decomposition, Carbon Cycling and Storage in Cefni

Coastal Salt Marsh, Anglesey Island, Wales, United Kingdom. European Journal of Applied Sciences, Vol - 12(5). 204-216.

Services for Science and Education – United Kingdom

Examining Microbial Decomposition, Carbon Cycling and Storage

in Cefni Coastal Salt Marsh, Anglesey Island, Wales, United

Kingdom

Dasat, G. S.

Department of Science,

Plateau State Polytechnic Barkin Ladi, Jos Nigeria

Christopher, F.

College of Natural Science Bangor University, Wales UK

Tim, J.

College of Natural Science Bangor University, Wales UK

Dunn, C.

College of Natural Science Bangor University, Wales UK

ABSTRACT

Salt marshes sequester carbon dioxide from the atmosphere into the soil,

however, anthropogenic activities could release centuries of buried carbon

dioxide, a major greenhouse gas implicated with climate change. Therefore, this

study investigated biogeochemical activities in soil samples from low, mid and

high zones of Cefni salt marsh, within the Maltreat estuary, on the island of

Anglesey, north Wales, United Kingdom for a consortium of laboratory

experiments using standard operating protocols to quantify soil organic matter

contents and the rate of microbial decomposition and carbon storage. Results of

investigations reveals that the mid zone had 56.23% and 9.98% of soil water and

soil organic matter contents respectively higher than the low and high zones.

Phenol oxidase activity (1193.53μmol dicq g-1 h-1) was highest at the low zone

compared to the high and mid zones (867.60 and 608.74 μmol dicq g-1 h-1)

respectively. Soil phenolic concentration was highest in the mid zone (53.25 μg-1 g- 1) compared with high (15.66 μg-1 g-1) and low (4.18 μg-1 g-1) zones respectively.

Activities of hydrolases showed similar trend for the high and low zones and much

lower activities in the mid zone. CO2 flux from the mid zone (6.79 ug g-1 h-1) was

significantly greater than those from high (-2.29 ug g-1 h-1) and low (1.30 μg g-1 h-1)

zones. Since salt marshes provide essential ecosystem services, their degradation

or alteration in whatever form could compromise vital ecosystem services,

converting them from net sinks into net sources with consequential effects to the

global environment.

Keywords: Salt marsh, Decomposition, Carbon Cycling, Enzymes, Greenhouse gases.

INTRODUCTION

Most discussions of late on anthropogenic climate change is commonly centered on fossil fuel

emissions with less focus on the destruction of the natural ecosystems which accounts for

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205

Dasat, G. S., Christopher, F., Tim, J., & Dunn, C. (2024). Examining Microbial Decomposition, Carbon Cycling and Storage in Cefni Coastal Salt

Marsh, Anglesey Island, Wales, United Kingdom. European Journal of Applied Sciences, Vol - 12(5). 204-216.

URL: http://dx.doi.org/10.14738/aivp.125.17339

nearly 30% of global emissions of greenhouse gases (GHGs) [1]. Nevertheless, a number of

research investigations in relation to ecosystem destruction focuses mostly on terrestrial

deforestation with less attention on coastal wetlands ecosystems, even though the later

contain much more carbon stocks per unit area than that of the forests. But in recent years,

some researchers have started paying attention in the carbon stored in coastal and marine

ecosystems thereby generating more interest to carbon-dense stocks in the salt marsh

ecosystems [1].

Coastal salt marshes are considered as one of the Worlds’ most valued ecosystems due to its

promising potential to store blue carbon which is one of the most valuable GHGs mitigating

the effect of climate change [2]. Blue carbon is carbon stored in the biomass and deep

sediments of vegetated coastal ecosystems such as tidal marshes, mangroves, and sea grass

beds [3].Therefore, Barry et al. (2022) & Macreadie et al. (2013) [4&5] submitted that salt

marshes could sequester substantial quantities of atmospheric carbon dioxide (CO2) and

burry sedimentary carbon for several decades at the rate of 55 times faster than tropical

rainforests. Similarly, Macreadie et al. (2013) and Orson et al. (2018) [5 &3] submitted that

salt marshes in their natural state could consistently sequester and bury carbon in soil

sediments much faster and greater than those stored in rainforests.

Alongi (2020) [6] opined that salt marshes are among the most productive and vital

ecosystems globally and can hold up to 334 Mg CORG ha1 of carbon in storage as below ground

mass and can sequester more than 24% net primary production (NPP) than mangroves

(12%).

Saltmarsh ecosystems are well known for supporting rich mixture of terrestrial and marine

biodiversity forming unique estuarine food webs, and play an important role in linking food

webs, inorganic and organic materials, and biogeochemical cycles between the coast and

adjacent coastal zone [7].

Similarly, Cragg et al. (2020) [8] asserted that salt marshes and mangroves harbor few plant

species, but they are functionally complex, having ecosystem attributes similar to those of

other grasslands and forests.

Mcleod et al. (2011) & Macreadie et al. (2013) [9&5] noted that though salt marshes occupy

only 0.5% of terrestrial soil globally, they could sequester an estimated blue carbon of up to

87.2 ± 9.6 Tg C yr1 which is far greater than that of tropical rainforests (53 ± 9.6 Tg C yr-1).

Whereas, Sousa et al. (2017) [10] posited that coastal salt marshes could bury carbon at a rate

of 245 ± 26 g C m−2 y−1. Arriola & Cable (2017) [11] stated that carbon burial in salt marshes

ranges from 49.5-109.5 g C m-2 y−1, asserting that factors such as vegetation type and density,

period of inundation, sediment sources and geomorphology being the reasons for variability

in storage rates.

The high burial rate of carbon in salt marshes is not unconnected to the net primary

production exceeding that of decomposition thereby encouraging huge built ups of organic

matter in such soil environment [12]. Consequently, the high accretion of organic matter in

such ecosystem as a result of low microbial decomposition rates is atrributed to its anoxic

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European Journal of Applied Sciences (EJAS) Vol. 12, Issue 5, October-2024

condition. Accordingly, Orsan (2018) & Perera et al. (2022) [3&7] pointed out that soil

temperature, microbial community, redox potentials, vegetation type and hydrology regime

are the main factors impacting on the rate of decomposition of organic matter in salt marsh

ecosystems.

Decomposition rates in salt marsh ecosystem have been identified as a key control of the

build-up of organic matter, promoting net carbon sequestration and storage which plays a

vital role in protecting coastal ecosystems from the effect of climate change [13,4].

Furthermore, coastal salt marsh habitats provide vital ecosystem services to coastal

communities including protection from soil erosion, protection from the danger of rising sea

level and as an important tool in mitting the effect of climate change [14,15&16].

Despite the important ecosystem services of salt marshes, anthropogenically induced

activities and natural causes continue to threaten this all-important ecosystem. As a result, an

estimated 25% of global salt marshes has been lost since the 18th century [12,17,13].

Therefore, Hopkinson et al. (2012) & Arriola & Cable, (2017) [18 &11] stated that globally,

salt marshes are declining at 0.7–7% annually. This rate of loss if sustained could convert

these ecosystems from net sinks to net sources with serious implications for global carbon

storage and could aggravate global warming.

Therefore, the degradation of these vital coastal ecosystems mostly due to anthropogenic

activities is currently estimated to release up to 1.02 Pg of carbon dioxide annually [1].

Accordingly, quantifying anthropogenic effects on coastal wetlands and their carbon

sequestration ability, is critical in addressing the existing knowledge gaps in understanding of

the global carbon cycle, which is a fundamental in climate change mitigation and adaptation

strategy. Consequently, there still exits some important uncertainties such as depth, spatial

extent and carbon content in this quantification efforts [1].

In recent times there is a growing interest in estimation of wetland carbon stock as a vital tool

in counterbalancing the effect of climate change, large knowledge gaps and uncertainties still

remain, particularly in coastal salt marshes. Therefore, this investigation seeks to quantify the

carbon stock and cycling by examining the soil organic matter contents and the process of

microbial decomposition in the low, mid and high zones of the Cefni salt marsh soils in north

Wales, UK. It is therefore hypothesised that the low zone of the salt marsh will have a higher

carbon stock than the mid and high zones due to frequent flooding by seawater and therefore

more anoxic.

METHODOLOGY

Study Site and Sample Collection

Samples of soil for laboratory analyses were collected from Cefni salt marsh (Figure 1), within

the Maltreat estuary, on the island of Anglesey, north Wales, United Kingdom (SH400664).

The region is protected for its sand dune and salt marsh habitat under Site of Special Scientific

Interest and Conservation designations. The area is dominated by Atlantic Salt Meadow and

Salicornia species plants. This habitat is characterised into three zones of low, mid and high

zones base on proximity to the sae and gradient with the low zone being the closest to the

water edge and poorly vegetated with a longer inundation period due to tidal action, followed