scholarly journals The Role of Predator Removal by Fishing on Ocean Carbon Dynamics

2021 ◽  
Author(s):  
Richard Stafford ◽  
Zach Boakes ◽  
Alice E. Hall ◽  
Georgia C. A. Jones
Keyword(s):  
Trophic Level ◽  
Carbon Dynamics ◽  
Predatory Fish ◽  
Predator Removal ◽  
Phytoplankton Communities ◽  
Total Fish ◽  
Ocean Carbon ◽  
Ocean Sequestration ◽  
Global Carbon

AbstractTotal ocean carbon exceeds 40,000 GT either dissolved in the water column or buried in ocean sediments, and the ocean continues to sequester carbon from the atmosphere. Selective removal of predatory fish through extractive fishing alters the community structure of the ocean. This altered community results in increased biomass of more productive, low trophic level fish, higher overall fish respiration rates and lower carbon sequestration rates from fish, despite possible decreases in total fish biomass. High-pressure fishing on high trophic level fish, a globally occurring phenomenon, may result in as much as a 19% increase in respiration from fish communities overall. This increase in respiration will reduce sequestration rates and could prove highly significant in global carbon budgets. Preliminary estimates suggest a loss of sequestration equating to around 90Mt C.year−1 (~ 10% of total ocean sequestration or ~ 1% of anthropogenic fossil fuel emissions per year). Ultimately, to reduce these carbon emissions, fishing needs to be carbon optimised, alongside other fisheries management outcomes, which may mean that fewer higher trophic level fish are removed. This study highlights the potential magnitude of fishing on ocean carbon dynamics and presents the key uncertainties (including understanding the effects of fishing on zoo- and phytoplankton communities) we need to urgently research to accurately quantify the effects and model future fishing practices. Graphical Abstract

scholarly journals The role of predator removal by fishing on ocean carbon dynamics

2021 ◽  
Author(s):  
Rick Stafford ◽  
Zach Boakes ◽  
Alice Hall ◽  
Georgia Jones
Keyword(s):  
Predatory Fish ◽  
Fish Biomass ◽  
Predator Removal ◽  
High Productivity ◽  
Respiration Rates ◽  
Total Fish ◽  
Ocean Carbon ◽  
Global Carbon ◽  
Phytoplankton Photosynthesis

Abstract The ocean is a net sequester of carbon dioxide, predominantly through low biomass, high productivity phytoplankton photosynthesis. Selective removal of predatory fish through extractive fishing alters the community structure of the ocean, with an increased biomass of more productive, low trophic level fish and higher overall respiration rates, despite possible decreases in total fish biomass. High pressure fishing on predators may result in as much as a 19% increase in respiration from fish communities and could prove highly significant in global carbon budgets.

scholarly journals CO2 dynamics and heterogeneity in a cave atmosphere: role of ventilation patterns and airflow pathways

2021 ◽  
Author(s):  
Lovel Kukuljan ◽  
Franci Gabrovšek ◽  
Matthew D. Covington ◽  
Vanessa E. Johnston
Keyword(s):  
Temporal Variations ◽  
Observation Point ◽  
Spatially Distributed ◽  
Combined Action ◽  
Karst Systems ◽  
The Relationship ◽  
Co2 Dynamics ◽  
Global Carbon

AbstractUnderstanding the dynamics and distribution of CO2 in the subsurface atmosphere of carbonate karst massifs provides important insights into dissolution and precipitation processes, the role of karst systems in the global carbon cycle, and the use of speleothems for paleoclimate reconstructions. We discuss long-term microclimatic observations in a passage of Postojna Cave, Slovenia, focusing on high spatial and temporal variations of pCO2. We show (1) that the airflow through the massif is determined by the combined action of the chimney effect and external winds and (2) that the relationship between the direction of the airflow, the geometry of the airflow pathways, and the position of the observation point explains the observed variations of pCO2. Namely, in the terminal chamber of the passage, the pCO2 is low and uniform during updraft, when outside air flows to the site through a system of large open galleries. When the airflow reverses direction to downdraft, the chamber is fed by inlets with diverse flow rates and pCO2, which enter via small conduits and fractures embedded in a CO2-rich vadose zone. If the spatial distribution of inlets and outlets produces minimal mixing between low and high pCO2 inflows, high and persistent gradients in pCO2 are formed. Such is the case in the chamber, where vertical gradients of up to 1000 ppm/m are observed during downdraft. The results presented in this work provide new insights into the dynamics and composition of the subsurface atmosphere and demonstrate the importance of long-term and spatially distributed observations.

scholarly journals The changing global carbon cycle: linking plant-soil carbon dynamics to global consequences

2009 ◽  
Vol 97 (5) ◽  
pp. 840-850 ◽  
Author(s):  
F. Stuart Chapin III ◽  
Jack McFarland ◽  
A. David McGuire ◽  
Eugenie S. Euskirchen ◽  
Roger W. Ruess ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Soil Carbon ◽  
Carbon Dynamics ◽  
Global Carbon Cycle ◽  
Soil Carbon Dynamics ◽  
Plant Soil ◽  
Global Carbon

scholarly journals A Model Study on the Role of Wetland Zones in Lake Eutrophication and Restoration

2001 ◽  
Vol 1 ◽  
pp. 605-614 ◽  
Author(s):  
J.H. Janse ◽  
W. Ligtvoet ◽  
S. Van Tol ◽  
A.H.M. Bresser
Keyword(s):  
Nutrient Loading ◽  
Predatory Fish ◽  
Nutrient Concentrations ◽  
Fish Stock ◽  
Mixing Rate ◽  
Marsh Vegetation ◽  
Model Calculations ◽  
Critical Loading ◽  
Marsh Area

Shallow lakes respond in different ways to changes in nutrient loading (nitrogen, phosphorus). These lakes may be in two different states: turbid, dominated by phytoplankton, and clear, dominated by submerged macrophytes. Both states are self-stabilizing; a shift from turbid to clear occurs at much lower nutrient loading than a shift in the opposite direction. These critical loading levels vary among lakes and are dependent on morphological, biological, and lake management factors. This paper focuses on the role of wetland zones. Several processes are important: transport and settling of suspended solids, denitrification, nutrient uptake by marsh vegetation (increasing nutrient retention), and improvement of habitat conditions for predatory fish. A conceptual model of a lake with surrounding reed marsh was made, including these relations. The lake-part of this model consists of an existing lake model named PCLake[1]. The relative area of lake and marsh can be varied. Model calculations revealed that nutrient concentrations are lowered by the presence of a marsh area, and that the critical loading level for a shift to clear water is increased. This happens only if the mixing rate of the lake and marsh water is adequate. In general, the relative marsh area should be quite large in order to have a substantial effect. Export of nutrients can be enhanced by harvesting of reed vegetation. Optimal predatory fish stock contributes to water quality improvement, but only if combined with favourable loading and physical conditions. Within limits, the presence of a wetland zone around lakes may thus increase the ability of lakes to cope with nutrients and enhance restoration. Validation of the conclusions in real lakes is recommended, a task hampered by the fact that, in the Netherlands, many wetland zones have disappeared in the past.

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