Influence of predicted sea-level rise on the salt marsh of the Swartkops, Kromme and Knysna estuaries
- Authors: Schmidt, Jadon
- Date: 2013
- Subjects: Sea-level -- South Africa , Salt marshes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3765 , vital:20462
- Description: Salt marshes are coastal wetlands that are highly productive and biologically diverse ecosystems. These systems are under threat from rising sea levels which are predicted to accelerate in the future. Salt marsh habitats of the Swartkops, Kromme and Knysna estuaries were examined to determine their structure along an elevation gradient and how this structure has changed over the past six decades, what the primary drivers of this structure were and whether the salt marsh surface is stable, rising or declining relative to predicted sea level rise. During this study the following main hypothesis was tested: The environmental drivers of salt marsh zonation are elevation above mean sea level (AMSL), soil moisture and soil salinity, all of which will be impacted by the predicted rise in sea level of 1.48 mm.y-1, unless the salt marshes are able to accrete at a rate such that surface elevation gain is sufficient to offset the rate of sea level rise. The results showed that the salt marsh vegetation structure followed a predictable pattern down the elevation gradient with distinct supratidal, intertidal and subtidal habitats identified for each estuary. These three zones occurred between elevations around Mean Sea Level of -0.86 to 2.42 AMSL for Swartkops, -0.3 to 2.95 m AMSL for Kromme and -0.48 to 3.14 m AMSL for Knysna. A floodplain component was also identified in the Swartkops estuary, which was restricted to the upper reaches. During the last 60 years, losses of intertidal and supratidal salt marsh for Swartkops were 74.31 ha and 30.23 ha respectively, 17.01 ha of intertidal and supratidal salt marsh was lost in Kromme while intertidal salt marsh in Knysna has diminished by 168 ha. These losses were mainly attributed to developmental pressure, although there are indications that rising sea levels are becoming more influential in the lower reaches. The main environmental drivers for salt marsh structure in the Swartkops were shown to be soil moisture content and elevation, soil moisture and organic content for Kromme while elevation and soil redox potential were dominant in Knysna. In a comparison of all three systems, soil moisture content and redox potential were found to be the most important drivers of vegetation distribution. Elevation dictates tidal inundation periodicity and frequency, and thus acts to influence all edaphic factors driving vegetation distribution. Results indicated that the salt marsh surface elevation of the lower and middle sections of the Swartkops, Kromme and Knysna estuaries are generally declining relative to current sea level rise. Where increases in surface elevation (relative to current sea level rise) were recorded, the majority of the accretion occurred after episodic flooding in winter 2011. These increases typically occurred in the upper reaches and were attributed to the deposition of fluvial sediments as a result of these floods. Results for Knysna indicate that while a majority of the salt marsh surface is accreting vertically, only three areas are increasing their elevation at a rate at least equal to current sea level rise. In these areas, developmental pressures will prevent a landward transgression of the salt marsh, forming an artificial “coastal squeeze”. Geomorphological limitations (steep hills adjacent to the salt marsh) will prevent any transgression in the upper reaches of the Kromme Estuary. Supratidal habitat in the upper reaches of the Swartkops estuary, if undeveloped, will provide the only viable habitat for the salt marsh to migrate into, given sufficient surface elevation.
- Full Text:
- Date Issued: 2013
- Authors: Schmidt, Jadon
- Date: 2013
- Subjects: Sea-level -- South Africa , Salt marshes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3765 , vital:20462
- Description: Salt marshes are coastal wetlands that are highly productive and biologically diverse ecosystems. These systems are under threat from rising sea levels which are predicted to accelerate in the future. Salt marsh habitats of the Swartkops, Kromme and Knysna estuaries were examined to determine their structure along an elevation gradient and how this structure has changed over the past six decades, what the primary drivers of this structure were and whether the salt marsh surface is stable, rising or declining relative to predicted sea level rise. During this study the following main hypothesis was tested: The environmental drivers of salt marsh zonation are elevation above mean sea level (AMSL), soil moisture and soil salinity, all of which will be impacted by the predicted rise in sea level of 1.48 mm.y-1, unless the salt marshes are able to accrete at a rate such that surface elevation gain is sufficient to offset the rate of sea level rise. The results showed that the salt marsh vegetation structure followed a predictable pattern down the elevation gradient with distinct supratidal, intertidal and subtidal habitats identified for each estuary. These three zones occurred between elevations around Mean Sea Level of -0.86 to 2.42 AMSL for Swartkops, -0.3 to 2.95 m AMSL for Kromme and -0.48 to 3.14 m AMSL for Knysna. A floodplain component was also identified in the Swartkops estuary, which was restricted to the upper reaches. During the last 60 years, losses of intertidal and supratidal salt marsh for Swartkops were 74.31 ha and 30.23 ha respectively, 17.01 ha of intertidal and supratidal salt marsh was lost in Kromme while intertidal salt marsh in Knysna has diminished by 168 ha. These losses were mainly attributed to developmental pressure, although there are indications that rising sea levels are becoming more influential in the lower reaches. The main environmental drivers for salt marsh structure in the Swartkops were shown to be soil moisture content and elevation, soil moisture and organic content for Kromme while elevation and soil redox potential were dominant in Knysna. In a comparison of all three systems, soil moisture content and redox potential were found to be the most important drivers of vegetation distribution. Elevation dictates tidal inundation periodicity and frequency, and thus acts to influence all edaphic factors driving vegetation distribution. Results indicated that the salt marsh surface elevation of the lower and middle sections of the Swartkops, Kromme and Knysna estuaries are generally declining relative to current sea level rise. Where increases in surface elevation (relative to current sea level rise) were recorded, the majority of the accretion occurred after episodic flooding in winter 2011. These increases typically occurred in the upper reaches and were attributed to the deposition of fluvial sediments as a result of these floods. Results for Knysna indicate that while a majority of the salt marsh surface is accreting vertically, only three areas are increasing their elevation at a rate at least equal to current sea level rise. In these areas, developmental pressures will prevent a landward transgression of the salt marsh, forming an artificial “coastal squeeze”. Geomorphological limitations (steep hills adjacent to the salt marsh) will prevent any transgression in the upper reaches of the Kromme Estuary. Supratidal habitat in the upper reaches of the Swartkops estuary, if undeveloped, will provide the only viable habitat for the salt marsh to migrate into, given sufficient surface elevation.
- Full Text:
- Date Issued: 2013
The potential impact of diving charges on the demand for diving and the diving industry in the Aliwal Shoal Marine Protected Area: a pilot study
- Authors: Schmidt, Jadon
- Date: 2011
- Subjects: Marine parks and reserves -- South Africa -- KwaZulu-Natal Recreational dive industry -- South Africa -- KwaZulu-Natal Recreational dive industry -- Licenses -- South Africa -- KwaZulu-Natal Marine parks and reserves -- South Africa -- KwaZulu-Natal -- Management Conservation of natural resources -- South Africa -- KwaZulu-Natal Environmental management -- South Africa -- KwaZulu-Natal Marine resources conservation -- South Africa -- KwaZulu-Natal Waste disposal in the ocean -- South Africa -- KwaZulu-Natal Marine pollution -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:756 , http://hdl.handle.net/10962/d1003877
- Description: This research is presented in three sections. Section 1 presents the research report in an Academic Paper format. Section 2 provides a comprehensive literature review and Section 3 describes the research methodology and methods employed. Sustainable management of natural resources is a global imperative. It is particularly significant in a country like South Africa that is blessed with an abundance of biological diversity but faces many socio economic challenges that are associated with developing nations. Toward addressing these issues, diver permit fees were implemented in South Africa in 2005, making it a legal requirement for all scuba divers undertaking a dive in a Marine Protected Area (MPA) to purchase a permit. This pilot study is the first attempt since the inception of the dive permit fees to determine their impact on the demand for diving and the diving industry in the Aliwal Shoal MPA, one of the premier dive destinations in the country. In order to address key questions, qualitative data was gathered during interviews with 12 dive operators active in the MPA and 28 divers that utilised the operators to dive. In addition, independent quantitative data on the number of dive boat launches during the past 20 years was used in conjunction with mean paying diver data obtained from the operators to ascertain the demand for diving at the Aliwal Shoal during the past two decades. Results indicate that were no significant differences (at the 5% level of significance) between paying divers during 2005 compared to 2004 and 2006 [H =.1923366, N= 36, p =0.9083]. Paying diver data for the period 2000 - 2004 were compared to 2005 - 2010 and no significant differences were found at the 5% level of significance (U= 2040, Npost = 72, Npre= 60, p = 0.584981). Diver interviews revealed that only 36% of divers had paid for a permit, representing a loss of R7 438 499 during the past five years, enough to support the current budget of the MPA for 10.6 years. Operator interviews revealed that alternative destinations, economic climate and local competition had the most impact on their businesses, with permit fees having no impact on the 50% of the operators’ businesses. Operators also reported that there was little or no enforcement of the permit fees, 9 of the operators indicated that there has been no improvement in the MPA or its management since the inception of the fees and all were dissatisfied with the current management MPA. Operators and divers complained about the current purchasing and handling practices associated with the permits. Despite offering a world class diving opportunity, the dive operators currently have no incentive to enforce the permit system and due to price pressure in the local market, and have adopted a mute stance on diver permits. Consequently, there has been no significant impact on the demand for diving since the inception of the permits in 2005. The initial hypothesis that the increased costs to divers as a result of the permits would drive down the demand for diving is therefore rejected. If the permits are more strictly enforced, it is likely that more divers may seek alternative destinations due to the perception of poor value as a result of the Sappi Saiccor effluent discharge, existence of shark nets and poor management, in accordance with existing literature. The resultant decrease in demand will be detrimental to the diving industry at Aliwal Shoal. The second hypothesis, that the costs associated with the better enforcement of the MPA regulations-in terms of impacts on the diving industry- might outweigh the benefits, is therefore accepted. All the results produced by this study suggest that authorities may have been too enthusiastic to have all the boxes ticked in order to meet deadlines for international targets for marine conservation and paid little or no attention to lessons learnt from MPAs globally. Every negative aspect highlighted by existing international literature as symptomatic of MPA failure is occurring at Aliwal Shoal MPA, albatrossing it with “paper park” status. Due to the size and scope of this study, the results should be interpreted with caution and not be utilised to guide policy but rather encourage further research.
- Full Text:
- Date Issued: 2011
- Authors: Schmidt, Jadon
- Date: 2011
- Subjects: Marine parks and reserves -- South Africa -- KwaZulu-Natal Recreational dive industry -- South Africa -- KwaZulu-Natal Recreational dive industry -- Licenses -- South Africa -- KwaZulu-Natal Marine parks and reserves -- South Africa -- KwaZulu-Natal -- Management Conservation of natural resources -- South Africa -- KwaZulu-Natal Environmental management -- South Africa -- KwaZulu-Natal Marine resources conservation -- South Africa -- KwaZulu-Natal Waste disposal in the ocean -- South Africa -- KwaZulu-Natal Marine pollution -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:756 , http://hdl.handle.net/10962/d1003877
- Description: This research is presented in three sections. Section 1 presents the research report in an Academic Paper format. Section 2 provides a comprehensive literature review and Section 3 describes the research methodology and methods employed. Sustainable management of natural resources is a global imperative. It is particularly significant in a country like South Africa that is blessed with an abundance of biological diversity but faces many socio economic challenges that are associated with developing nations. Toward addressing these issues, diver permit fees were implemented in South Africa in 2005, making it a legal requirement for all scuba divers undertaking a dive in a Marine Protected Area (MPA) to purchase a permit. This pilot study is the first attempt since the inception of the dive permit fees to determine their impact on the demand for diving and the diving industry in the Aliwal Shoal MPA, one of the premier dive destinations in the country. In order to address key questions, qualitative data was gathered during interviews with 12 dive operators active in the MPA and 28 divers that utilised the operators to dive. In addition, independent quantitative data on the number of dive boat launches during the past 20 years was used in conjunction with mean paying diver data obtained from the operators to ascertain the demand for diving at the Aliwal Shoal during the past two decades. Results indicate that were no significant differences (at the 5% level of significance) between paying divers during 2005 compared to 2004 and 2006 [H =.1923366, N= 36, p =0.9083]. Paying diver data for the period 2000 - 2004 were compared to 2005 - 2010 and no significant differences were found at the 5% level of significance (U= 2040, Npost = 72, Npre= 60, p = 0.584981). Diver interviews revealed that only 36% of divers had paid for a permit, representing a loss of R7 438 499 during the past five years, enough to support the current budget of the MPA for 10.6 years. Operator interviews revealed that alternative destinations, economic climate and local competition had the most impact on their businesses, with permit fees having no impact on the 50% of the operators’ businesses. Operators also reported that there was little or no enforcement of the permit fees, 9 of the operators indicated that there has been no improvement in the MPA or its management since the inception of the fees and all were dissatisfied with the current management MPA. Operators and divers complained about the current purchasing and handling practices associated with the permits. Despite offering a world class diving opportunity, the dive operators currently have no incentive to enforce the permit system and due to price pressure in the local market, and have adopted a mute stance on diver permits. Consequently, there has been no significant impact on the demand for diving since the inception of the permits in 2005. The initial hypothesis that the increased costs to divers as a result of the permits would drive down the demand for diving is therefore rejected. If the permits are more strictly enforced, it is likely that more divers may seek alternative destinations due to the perception of poor value as a result of the Sappi Saiccor effluent discharge, existence of shark nets and poor management, in accordance with existing literature. The resultant decrease in demand will be detrimental to the diving industry at Aliwal Shoal. The second hypothesis, that the costs associated with the better enforcement of the MPA regulations-in terms of impacts on the diving industry- might outweigh the benefits, is therefore accepted. All the results produced by this study suggest that authorities may have been too enthusiastic to have all the boxes ticked in order to meet deadlines for international targets for marine conservation and paid little or no attention to lessons learnt from MPAs globally. Every negative aspect highlighted by existing international literature as symptomatic of MPA failure is occurring at Aliwal Shoal MPA, albatrossing it with “paper park” status. Due to the size and scope of this study, the results should be interpreted with caution and not be utilised to guide policy but rather encourage further research.
- Full Text:
- Date Issued: 2011
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