Effect of sedimentation increase on Antarctic benthic Ecosystem: a mathematical approach in a Global Warming context

LUCIANA TORRE; RICARDO SAHADE; FERNANDO MOMO; JOAO MEYER

Campos do Jordão, S.P., Brazil

Simposio; International Symposium on Mathematical and Computational Biology (BIOMAT); 2008

Together with the Arctic, the Antarctic Peninsula is one of the regions on earth with the clearest evidence of recent rapid air warming as a consequence of the global warming trend. Air temperature has risen by 2.5C in the last 50 years and, in some areas of the Antarctic Peninsula, has caused massive glacier retreat leading to an increase in the influx of glacier meltwater. This entails hydrographical change in coastal waters, the effects of which on the coastal ecosystems, both marine and terrestrial, are not yet well understood. Changes observed in the area during the past years include increase of ice-scouring frequency and sediment discharge intensity. In Potter Cove (King George Island, South Shetland, Antarctica) changes in several hydrographic parameters have been observed, in particular surface freshening and warming, as well as a sediment concentration increase. During the same period remarkable changes in the benthic macrofauna community were reported. In order to analyze and to obtain a better understanding of the effect of sedimentation increase upon species of the benthic community of this region, and to be able to test hypothesis of the above mentioned effects, a mathematical model is proposed, discretized and an algorithmic scheme is designed in order to undertake numerical simulations. This model takes into account population dispersal, population dynamics including competition for space in and among species, as well as possible lethal effects of increase in sediment discharge: We defined four biological groups, according to the different life trails of these benthic organisms. Group A includes the stalked ascidians (Cnemidocarpa verrucosa and Molgula pedunculata) that are capable of excluding other ascidians by competition but are the most sensitive species to sediment disturbances. Group B is formed by flat ascidians, mainly Ascidia challengeri and Corella eumyota. These tunicates are less sensitive to sediment disturbance. Group C is the population of bivalves, particularly Laternula elliptica that is an infaunal species and may resist the ice perturbation. Finally group D is formed by pennatulids (sea pens). These organisms are not strong competitors but exhibit high growth rates. In consequence, they constitute the “pioneer” species that colonize empty habitats after physical disturbances events took place. For a concentration of sediment given by p(x,y,t) and for populations A(x,y,t), B(x,yt,), C(x,y,t) and D(x,y,t), the proposed non-linear system of partial differential equations on a domain
R2 is given by: This system takes into account diffusion and transport of sediment, population dynamics, competition in and between species using a classical Lotka-Volterra-type terms and a mortality term due to the effects of sediment. With the developed algorithm, and using a MATLAB environment, numerical simulations were undertaken for different scenarios of colonization, with different sedimentation rates in order to evaluate the effect of this phenomenon on biological dynamics. One of the main objectives is to compare these results with field data. The model not only recreates the community pattern but seems to be also able to recreate the modifications related to the increase in ice melting with the correlate enhancement of inorganic particles in the water column. Presentation will include visual and qualitative results of the above-mentioned evolutive behaviours. Antarctica is probably one of the most extreme places in the world where experimental work is always a challenge. In this context mathematical models are a powerful tool for studying, understanding and predicting the effects of the Climate Change on the ecosystems and to determinate the significance of involved phenomena.Cnemidocarpa verrucosa and Molgula pedunculata) that are capable of excluding other ascidians by competition but are the most sensitive species to sediment disturbances. Group B is formed by flat ascidians, mainly Ascidia challengeri and Corella eumyota. These tunicates are less sensitive to sediment disturbance. Group C is the population of bivalves, particularly Laternula elliptica that is an infaunal species and may resist the ice perturbation. Finally group D is formed by pennatulids (sea pens). These organisms are not strong competitors but exhibit high growth rates. In consequence, they constitute the “pioneer” species that colonize empty habitats after physical disturbances events took place. For a concentration of sediment given by p(x,y,t) and for populations A(x,y,t), B(x,yt,), C(x,y,t) and D(x,y,t), the proposed non-linear system of partial differential equations on a domain
R2 is given by: This system takes into account diffusion and transport of sediment, population dynamics, competition in and between species using a classical Lotka-Volterra-type terms and a mortality term due to the effects of sediment. With the developed algorithm, and using a MATLAB environment, numerical simulations were undertaken for different scenarios of colonization, with different sedimentation rates in order to evaluate the effect of this phenomenon on biological dynamics. One of the main objectives is to compare these results with field data. The model not only recreates the community pattern but seems to be also able to recreate the modifications related to the increase in ice melting with the correlate enhancement of inorganic particles in the water column. Presentation will include visual and qualitative results of the above-mentioned evolutive behaviours. Antarctica is probably one of the most extreme places in the world where experimental work is always a challenge. In this context mathematical models are a powerful tool for studying, understanding and predicting the effects of the Climate Change on the ecosystems and to determinate the significance of involved phenomena.Ascidia challengeri and Corella eumyota. These tunicates are less sensitive to sediment disturbance. Group C is the population of bivalves, particularly Laternula elliptica that is an infaunal species and may resist the ice perturbation. Finally group D is formed by pennatulids (sea pens). These organisms are not strong competitors but exhibit high growth rates. In consequence, they constitute the “pioneer” species that colonize empty habitats after physical disturbances events took place. For a concentration of sediment given by p(x,y,t) and for populations A(x,y,t), B(x,yt,), C(x,y,t) and D(x,y,t), the proposed non-linear system of partial differential equations on a domain
R2 is given by: This system takes into account diffusion and transport of sediment, population dynamics, competition in and between species using a classical Lotka-Volterra-type terms and a mortality term due to the effects of sediment. With the developed algorithm, and using a MATLAB environment, numerical simulations were undertaken for different scenarios of colonization, with different sedimentation rates in order to evaluate the effect of this phenomenon on biological dynamics. One of the main objectives is to compare these results with field data. The model not only recreates the community pattern but seems to be also able to recreate the modifications related to the increase in ice melting with the correlate enhancement of inorganic particles in the water column. Presentation will include visual and qualitative results of the above-mentioned evolutive behaviours. Antarctica is probably one of the most extreme places in the world where experimental work is always a challenge. In this context mathematical models are a powerful tool for studying, understanding and predicting the effects of the Climate Change on the ecosystems and to determinate the significance of involved phenomena.Laternula elliptica that is an infaunal species and may resist the ice perturbation. Finally group D is formed by pennatulids (sea pens). These organisms are not strong competitors but exhibit high growth rates. In consequence, they constitute the “pioneer” species that colonize empty habitats after physical disturbances events took place. For a concentration of sediment given by p(x,y,t) and for populations A(x,y,t), B(x,yt,), C(x,y,t) and D(x,y,t), the proposed non-linear system of partial differential equations on a domain
R2 is given by: This system takes into account diffusion and transport of sediment, population dynamics, competition in and between species using a classical Lotka-Volterra-type terms and a mortality term due to the effects of sediment. With the developed algorithm, and using a MATLAB environment, numerical simulations were undertaken for different scenarios of colonization, with different sedimentation rates in order to evaluate the effect of this phenomenon on biological dynamics. One of the main objectives is to compare these results with field data. The model not only recreates the community pattern but seems to be also able to recreate the modifications related to the increase in ice melting with the correlate enhancement of inorganic particles in the water column. Presentation will include visual and qualitative results of the above-mentioned evolutive behaviours. Antarctica is probably one of the most extreme places in the world where experimental work is always a challenge. In this context mathematical models are a powerful tool for studying, understanding and predicting the effects of the Climate Change on the ecosystems and to determinate the significance of involved phenomena.
R2 is given by: This system takes into account diffusion and transport of sediment, population dynamics, competition in and between species using a classical Lotka-Volterra-type terms and a mortality term due to the effects of sediment. With the developed algorithm, and using a MATLAB environment, numerical simulations were undertaken for different scenarios of colonization, with different sedimentation rates in order to evaluate the effect of this phenomenon on biological dynamics. One of the main objectives is to compare these results with field data. The model not only recreates the community pattern but seems to be also able to recreate the modifications related to the increase in ice melting with the correlate enhancement of inorganic particles in the water column. Presentation will include visual and qualitative results of the above-mentioned evolutive behaviours. Antarctica is probably one of the most extreme places in the world where experimental work is always a challenge. In this context mathematical models are a powerful tool for studying, understanding and predicting the effects of the Climate Change on the ecosystems and to determinate the significance of involved phenomena.