Marine Ecology

Abstract

On the 25-26 January 2008 a diurnal study was conducted in Oso Bay Nueces County , Texas , by students from the Texas A M University-Corpus Christi . Samples were taken every four hours for a 24 hour period from five stations located within the bay . Each station had an associated sampling gear that was used there , these were shallow bag seine , deep bad seine , benthic sled , benthic core and plankton tow . Meteorological and Hydrographic data was collected at station one every four hours while at the other four stations , biological data was collected

using the specific sampling gear assigned to that station . After every sample organisms that were caught were identified and counted . Meteorological data gathered included air temperature , wind speed and wind direction while hydrological parameters tested included water temperature salinity , dissolved oxygen and pH . A collected during the diurnal study period

The Shannon-Wiener species diversity index was used to measure species diversity , and showed a result of 1 .69 , which was lower than for previous years . The Benthic sled showed to be the most productive with a species diversity of 2 .04 , while the Vegetated Benthic core showed the lowest diversity with a H ' value of 0 .59 . Plankton tow net results could not be quantified and were therefore not included in the results however , when compared with 2007 results from the same location it is clear that the two show similar trends in diversity and abundance

Introduction

Estuaries are formed along the coast at the interface between salt and freshwater and as such provide a wide array of diverse ecological habitats and niches , such as marshes , tidal flats and sea grass beds These unique environments fulfill many important ecological functions such as acting as protective nursery areas for many fish species and as important breeding grounds for migratory birds . They also act as important filtering systems for terrestrial toxins and pollutants (www .estauries .gov . Biologically , estuarine habitats are amongst the most highly productive ecosystems in the world , with only Coral Reefs having a higher species diversity . Because of their shallow and semi-enclosed nature as well as their reliance on the amounts of incoming saline and freshwater , estuaries are subject to intense fluctuations in abiotic factors such as salinity , temperature and pH on a daily basis . This means that estuarine species must be hardy and able to withstand these daily fluctuations . Most species found within estuaries are therefore euryhaline , meaning they are able to withstand a wide range of salinities (Tait and Dipper , 1998 . Tides and freshwater inflow are essential as they help to stabilize the salinity as well as provide the necessary nutrients for organisms living within the estuary (Bilton et al . 2002 . They also act to flush the system of wastes that would otherwise foul the water quality and lead to anoxic conditions (Britton and Morton , 1989 ) and are important for sediment transport which would otherwise fill up the estuary . Finally , tidal exchanges act to disperse larval organisms that use the estuary as a nursery area (Holt...