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Nobhula Nomvula
ENVS 319 Assignment 2: Research proposal
An investigation of climate and human activities as constraints for reliability of lake sediment archives in relation to Lake St Lucia Introduction
Lake sediment archives are viewed as exceptional as they contain variety of other materials suspended in it that are useful for palaeoclimatic studies (von Gruten et al, 2012; Smol, 2002). These can be referred to as multi-proxy analysis with the most common proxy occurring in sediment being fossil pollen. Lake sediments archives are obtained by drilling using a coring device such as gravity corer. Lake sediment archives have been the fascination of researchers of the Northern hemisphere and the tropics because of water availability, there are more lakes to study the lake sediments than the Southern hemisphere. Whereas the Southern hemisphere as whole lack studies on lake sediment archives, especially the arid to semi-arid southern Africa, this has resulted in inconclusive and discontinuous paalaeoclimatic records with low spatial resolution (Neumann et al, 2008). South Africa is no exception from scarcity of palaeoclimatic records, hence numerous palaeoclimatic studies have dwelled on springs and swamps (Neumann et al, 2008). Therefore the available palaeoclimatic have low spatial resolution such as the fossil pollen of St Lucia which is > 45000 year old also AMS dating reveal weak correlations of this the Holocene climate record (Neumann et al, 2008; Finch, 2005). Since the east coast of South Africa is relatively wetter due the presence of warm Mozambique current, most lake sediment archives used for palaeoclimate reconstruction are from the KwaZulu-Natal eastern coastline such as the Lake St Lucia estuarine lake which is the focus of this study. The lake St Lucia receives a mean precipitation of about 1000 mm on a yearly basis which is expected for a substantially subhumid eastern coastline of South Africa (Bate and Taylor, 2008). In other arid and semi-arid areas, lake sediment climate records are non-existent due to difficulties in dating, as the stratigraphy might have recurring hiatuses and subjected to contamination caused by immature organic matter and CO2 resulting inconclusive palaeoclimate record (Olago, 2001). Due to lack of research on lake sediment in South Africa, more research still critical. Also palaeolimnological studies on Lake St Lucia are limited, much of the available literature focus on other lakes in the Northern KwaZulu Natal coastline with many being based at Lake Eteza. The fact that Lake St Lucia is also an estuary makes it a unique site due to the hydrodynamic processes occurring in the estuary during mouth closure or openness (Lawrie and Stretch, 2011) Lake St Lucia has been recognised as the biggest coastal lagoon system in South Africa covering an extensive area of 350 km2 (Bate and Taylor, 2008). The lake has been also granted a UNESCO Heritage site status and also given a Ramsar wetland of international significance (Lawrie and Stretch, 2011). Since the lake is also a wetland, it is highly affected by anthropogenic activities like catchment land use changes, water pollution both from industries and domestic sources, water diversion or abstraction and mouth state manipulation (Lawrie and Stretch, 2011). Anthropogenic effect started through the introduction of agriculture to the uMfolozi floodplain in the 20th century (Lawrie and Stretch, 2011). Climate has also caused major changes to the lake such as the drought event that occurred during the period of years 2002-2006, which resulted in extremely high salinity and low lake levels (Bate and Taylor, 2008).

Aims and objectives of the study
The aim of the study is to determine if such changes affected the palaeoclimatic records or the use of these records by using sediment cores from the Lake St Lucia. There are three main research questions that are as follows; a) does the sediment sequence or stratigraphy show...
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