Biodiversity and community structure of free-living marine nematodes from intertidal areas in the Persian Gulf
Sahraean, N. (2017). Biodiversity and community structure of free-living marine nematodes from intertidal areas in the Persian Gulf. PhD Thesis. Ghent University, Faculty of Sciences: Gent. 233 pp.
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Document type: Dissertation
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| Abstract |
The Persian Gulf is a semi-enclosed marginal sea, connected to the Gulf of Oman through the Strait of Hormuz. About one third of the world’s oil is produced in this region. It is an important military, economic and political region due to its oil and gas resources and it is one of the most important waterways in the world. Moreover, the Persian Gulf is located in a subtropical, hyper-arid region with often extreme air temperatures, a high evaporation rate and hence a high water salinity. The Persian Gulf hosts a variety of marine habitats such as rocky shores, estuarine ecosystems, mangrove habitats, salt marshes, sandy beaches, mud flats and coral reefs. Intertidal mud flats and sandy beaches are among the most widespread coastal habitats in the area. Because of the intensive human exploitation, the Persian Gulf is considered as one of the world's most polluted bodies of water. In addition to often wide-ranging pollution from oil-related activities, industrialization, urbanization, local sewage discharges and the building of numerous piers and docks all pose potentially serious threats to the marine life in this strategic location. In this PhD study, focus is on the northeastern part of the Persian Gulf, specifically the area of Bandar Abbas, the capital city of the Hormuzgan province, which is situated in the southeast of Iran. In the Iranian part of the Persian Gulf, only biodiversity and distribution of macrobenthos taxa or assemblages in intertidal marine habitats have hitherto received some attention. The meiobenthos has remained a completely neglected component of the benthos. This PhD therefore provides the very first study on the free-living marine nematode assemblages in coastal habitats of the Persian Gulf. It thus contributes substantially to the knowledge of the coastal marine biodiversity in the Iranian part of the Persian Gulf. Since this is a pioneering study, we first investigate biodiversity of nematode assemblages with a focus on spatial patterns in relation to local (so non-overarching) point sources of pollution, asking the question whether in such a broadly stressed environment, local pollution sources would still have a measurable impact on nematode assemblages. For this purpose, we focus on four beaches, and within each beach location, we assign three stations at different distances from local point sources of pollution. We then repeat the same sampling design almost exactly one year later to get a first impression of the consistency of the obtained spatial patterns over time, more specifically year-to-year variability. Finally, we look into the population-genetic structure of the two most abundant nematode species across a somewhat broader stretch (52 km) of coastline with the aim of studying connectivity and gene flow between populations from beach locations at a scale at which in other population-genetic studies of coastal nematodes, significant structuring has regularly been observed. Since both nematode species studied here tend to occupy different depth layers of the sediment, we also tested the hypothesis that the surface-dwelling species would show a lesser population-genetic structuring compared to the real endobenthic species. |
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