Anthropogenic Impact on the Pulicat Lagoon Monitoring with Foraminifera, East coast of India

Abstract

Coastal lagoons are well investigated areas because of their economical and ecological importance. Pulicat Lagoon system which is a store house of all resources is under great threat following the anthropogenic pollution. This complex lagoon ecosystem's surface area is about 500 sq.kms. In spite of the System's conservation statutes its structure has been degenerating rapidly because of pressures fishing, tourism and agricultural activities. Fishing production of Pulicat Lagoon System is approximately 52 tons/ha/year. Although a serious fishery pressure has been determined in the area, according to mortality rate and age compositions, it has been found that the growth of marine life in the environment is in unhealthy condition. The date show that land based and atmospheric sources account about two-thirds of the total impact of contaminants in to the marine lagoon constituting 44 % and 33 % respectively. A total of 30 sediment samples were collected with in the depth zone of 5 fathoms from the lagoon. The study yielded 50 benthic foraminiferal species belongs to 24 genera, 16familys, 8 super families and 3 sub-orders. Variations are also reflected on the foraminiferal test morphology, diversity and distribution. A high percentage of foraminifers almost exclusively Ammonia have damaged shells with a few channels to entire whorl missing. The phenomenon is stress response to the anthropogenic pollution. The Ammonia-Elphidium assemblage is dominant in all stations followed by Spiroloculina -Bolivina assemblage.Suggestions for development of the lagoon management and maximum sustainable marine life production have been offered by determining the present lagoon management and some a biotic characteristics of this ecosystem. Many studies assume or conclude that foraminiferal assemblages and the frequency of deformed tests are proxy indicators of pollution, but others present confounding results. Under studying the complexity of anthropogenic pollution, coastal waters and sediment is critical to the design and interpretation of meaningful studies.Keywords Lake, Foraminifera, Ecology, Anthropogenic Pollution, Ecological Parameters 1.IntroductionThe study area, is located in the Survey of India toposheets nos: 66 B/2, 66 B/3, 66 C/2 respectively at the scale of 1: 50,000. The study area lies between longitudes 80o 02' -80o 20' E and latitudes 13o22'-13o 45' N (Fig.1). The total area of the lagoon is about 500 sq kms. The lake is marked by steeply rising ridges, having a height of about 17m from the mean sea level (MSL) and composed of Quartzites of Cuddapah Super group (Proterozoic) [1]. The steep and plain topography is due to the great difference in age between the Archean of the plain country and the Proterozoic of the high lands and also due to the greater resistance for erosion offered by quartzites compared to gneisses. The important ephemeral rivers that join the lake include Arani and Kalangi (Fig.1)[2]. Enormous quantities of fresh water influx along * Corresponding author: sundherreddy@gmail.com (Sundar...

Spatial and temporal analyses of salinity changes in Pulicat lagoon, a transitional ecosystem, during 1996–2015

“…Datasets for 1996Datasets for -1997Datasets for , 1999Datasets for -2000 and 2015 are coincident to high flood events as described in the literature (Padma & Periakali, 1999; No impact zone studies, 2003; Santhanam & Natarajan, 2018); we expected that these datasets could reflect high fluctuations in the salinities between premonsoon and postmonsoon periods, corresponding to low or no entrance closures. Data for 2000-2001 and 2007-2008 reflect the periods of lean monsoon (Ramesh et al, 2001;Reddy, Jayaraju, & Reddy, 2012). Such data could be useful to indicate the carryover of salinities post the periods of low precipitation.…”

“…To identify the entrance statuses, we used field investigation reports (Coulthard, 2008;IOM report, 2003;Nagarjuna, Kumar, Kalarani, & Reddy, 2010;Reddy et al, 2012) as well as selected satellite imageries from the Landsat 1-5 MSS imageries with a spatial resolution of 30 m and ETM+ (NASA Landsat Program, 2013; 20 scenes) licensed for free use by USGS and NASA, as well as Google Earth imageries from 1996 to 2015.…”

“…Data for 2015 are not included here. The statuses of connectivity to the sea (BoB) via the southern main entrance are marked as 'C' = closed; 'O' = open, visually interpreted using imageries from Google Earth and field reports (Coulthard, 2008;Nagarjuna et al, 2010;Reddy et al, 2012) without any band transformations or geospatial analyses.…”

Short-term desalination of Pulicat lagoon (Southeast India) due to the 2015 extreme flood event: insights from Land-Ocean Interactions in Coastal Zone (LOICZ) models

“…Several studies across the years provide a comprehensive understanding of the multi-environmental nature of the lagoon (e.g. Kaliyamurthy 1974, Radhakrishnan 1975, Ramesh et al 2002, Shalini et al 2006, Purvaja et al 2008, Reddy et al 2012and Jayakumar et al 2013). The two major fish landing centres at Pulicat and Arambakkam that contribute significantly to the socioeconomics of the region are located on the western shores of this lagoon, which is vulnerable to sudden salinity shifts.…”

“…We averaged the observed values to obtain a representative system salinity due the event to be used for the LOICZ modelling. For the purpose of comparison, we compiled the available salinity observations from the past pre-monsoon periods for the years 1997 (Padma and Periakali 1999), 1999(Institute of Ocean Management AUC 2003(Santhanam 2009), 2007(Reddy et al 2012) and 2015 (present investigation). We derived spatial interpolation plots for six datasets of post-monsoon salinities with observations at different sites within the lagoon, for the years 1997, 1999, 2005, 2006, 2007 and 2015 using the spline interpolation algorithm of Brovelli et al (2002) in GRASS GIS environment ( Fig.…”