Coastal wetlands, which act as buffer zones

between the marine and upstream land area, are

increasingly under pressure due to an array of

activities by multiple users. The wetlands are under

the influence of both fresh and saline water. Many

bird species including migratory seabirds and

resident coastal birds use wetlands as resting place,

for breeding or feeding purposes or to take cover

from predators

Kripa, V

Lavanya, S

Rohit, Prathibha

Sulochanan, Bindu

Lavanya, R

CMFRI Digital Repository

Mar. Fish. Infor. Serv., T & E Ser., No. 230, 2016 13made by the bull trawls result in insufficientpreservation leading to poor quality of the catchon reaching the harbour which  fetches lower pricesin the market as compared to catch made by regulartrawlers.The indiscriminate capture of juveniles by bulltrawls leads to growth overfishing and will have anadverse effect on the fishery. Operation of bull trawlin Karnataka was not prohibited till recently andthis type of fishing was carried out regularly alongthe coast. The Mangalore Research Centre of ICAR-CMFRI during its regular Stake Holders Meet, hascreated awareness among the trawl net operators,especially those practicing pair trawling on theharmful effects of large scale exploitation ofjuveniles and have urged the fishermen to refrainfrom such type of destructive fishing activities.Several fisher groups too started expressingconcerns on such unsustainable fishing practices andsome members of the Trawl Boat Owners Associationvoluntarily decided to stop this kind of fishing inthe near shore waters as well as tried to convinceother operators to stop such activities. However,this movement by a few fishers did not achieve muchsuccess and concerned stakeholders from severalquarters urged the Department of Fisheries,Government of Karnataka to take up some actionsto control bull/pair trawling activities. After severaldeliberations, the order (No: AHF 158 Dep. of Fish.Sch. 2016, Bengaluru dated 15-11-2016) to ban bulltrawling within 12 nautical miles (territorial waters)zone of Karnataka Coast  from 16th November 2016under the Karnataka Marine Fisheries Act,  wasissued by the Fisheries Department.Hydrodynamics of coastal wetlands in Dakshina Kannada and their importancefor avian faunaBindu Sulochanan1, S. Lavanya2,  Prathibha Rohit1 and V. Kripa21Mangalore Research Centre of ICAR-Central Marine Fisheries Research Institute, Mangaluru2ICAR-Central Marine Fisheries Research Institute, Kochie-mail: binduchaithanya@yahoo.co.inCoastal wetlands, which act as buffer zonesbetween the marine and upstream land area, areincreasingly under pressure due to an array ofactivities by multiple users. The wetlands are underthe influence of both fresh and saline water. Manybird species including migratory seabirds andresident coastal birds use wetlands as resting place,for breeding or feeding purposes or to take coverfrom predators. The Ramsar Convention onWetlands, of which India is a signatory, uses a broaddefinition of wetlands which includes all lakes andrivers, underground aquifers, swamps, marshes, wetgrasslands, peatlands, oases, estuaries, deltas, tidalflats, mangroves, other coastal areas, coral reefs,all human-made sites such as fish ponds, ricepaddies, reservoirs and salt pans. The contractingparties are committed to (a) work towards the wiseuse of all their wetlands;(b) designate suitablewetlands for the list of Wetlands of InternationalImportance (the “Ramsar List”) and ensure theireffective management;(c)cooperate internationallyon transboundary wetlands, shared wetland systemsand shared species.The coastal plain of Dakshina Kannada Districtin Karnataka is narrow and thickly populated.Though the district receives more than 3000 mmrainfall annually, problems such as flooding, coastalerosion, and salinity ingress in coastal aquifers andMar. Fish. Infor. Serv., T & E Ser., No. 230, 201614along river course exist and proper watermanagement strategies are required. The salinityingress of coastal aquifers is mainly during thesummer months when river flow decreases. Overthe years the percentage area of creeks, lagoon andwetlands in Dakshina Kannada has decreased dueto increasing urbanization resulting in loss of habitatto the multiple users of these wetland areas. Themotion or path of the water flow and the forceswhich act on the type of soil in the area determinesthe wetland formed. The most common feature ofall wetlands is that the water table (the groundwater level) is very near to the soil surface orshallow water covers for at least part of the year.The main characteristics of a wetland aredetermined by the combination of the salinity ofthe water in the wetland, the soil type and theplants and animals living in the wetland (Fig. 1).The coastal buffer zones of sandy beaches and marshlands help prevent saline water intrusion. Thetextural variation of a sandy shore with higher poresize helps in retention of fresh water during monsoonwhich in turn helps bind the grains together andaids in the growth of sand dune plants. The marshlands on the upstream have higher percentage ofclay, contain Kaolinite minerals joined by stronghydrogen bonds, and thus capable of retaining freshwater for longer duration even during dry weatherperiod.The coastal area between Baikampady (Fig. 2)and Chithrapur in Dakshina Kannada district ofKarnataka is a typical example of a coastal bufferzone. This wetland is a ‘Fern type’ and characterizedby peaty soil, with dominance of grass like plants,grasses, sedges and reeds. Peat soil is formed inwetland areas when plant material is inhibited fromdecaying fully due to anaerobic conditions. The‘Ferns type’ wetlands are alkaline, receiving watermostly from surface and subsurface flow. It receivessea water from the Arabian Sea during high tideand drains rainwater into the sea during monsoon.The subsurface flow is from upper Chithrapur areawhere marsh lands are present. However during theprocess of urbanization and development of citiesmost of these channels are converted into city wastewater drainages. Unfortunately, the preciousnutrient rich storm water mixes with waste waterand drains into the sea.  In the natural course whenrainfall is less, there is an inflow of saline waterinto the region. The higher the ground water tablealong the adjacent landmass, the less will be thesaline water intrusion due to hydrostatic pressuredifference in the system. However, during unplanneddevelopment activities, more of these precious andnatural marsh lands are filled with debris, hencedisturbing the natural balance of water flow in theseFig. 2. Coastal wetland and bird sighting areaFig. 1. Soil types in a wetlandMar. Fish. Infor. Serv., T & E Ser., No. 230, 2016 15ecosystems. The marsh lands on the upstream areaof Chithrapur, act as hydrologic sponge, temporarilystoring flood waters and releasing them slowly, thusreducing flood peaks and protecting downstreamareas. These functions are all the more importantin urban areas where development has increasedthe rate and volume of runoff. Wetlands generally host a number of avian faunaand the value of a wetland to a specific bird speciesis dependent on the moisture present in the soiland the duration and timing of flooding. At times,the water may not be present at the surface, butbe close enough to support growth of vegetationand organisms that are needed as food by birds.Birds generally use wetlands formed as depressionsin an otherwise dry landscape. These generally occuralong streams or in tidally influenced areas nearshorelines. The coastal birds especially the shanksand the sandpipers, feed on the beaches during earlymorning and late evening and take shelter in theinland areas as the beach sand heats up during theday time. The red-wattled lapwing Vanellus indicusanother  bird  sighted in this area scrape the groundand make small depressions on which they lay theireggs. Breeding season is during March to August.The  need for  lapwings to be near a wetland is thatthe adult  soak their belly feathers to provide waterto their chicks as well as to cool the eggs during hotweather. On the other hand the water hens preferto nest in the marsh lands and ponds in the upstreamareas. The decrease in number of sightings of thewater hens is an indicator of reduction in wetlandareas and stress on the ecosystem. The whitebreasted water hen Amaurornis phoenicurus is anomnivorous species preferring insects, molluscs,grains, shoots of paddy and marsh plants availablein its foraging area, which include grass land, mudand shallow water.  They usually nest during JuneRed-wattled lapwing Vanellus indicus(A) White breasted waterhen Amaurornis phoenicurus (B)Kentish plover Charadrius alexandrinus (C) Little ringedplover Charadrius dubius (D) Black headed gull Larusridibundus and Brown headed gull Larus brunnicephalusSchematic diagram of the hydrodynamics and soil type of a wetlandMar. Fish. Infor. Serv., T & E Ser., No. 230, 201616Abundance of natural fish seed resources prioritized for mariculture in theKali estuaryJayasree Loka, K. K. Philipose, Smruta Phal, K. Navanath, S. M. Sonali, N. G. VaidyaKarwar Research Centre of ICAR-Central Marine Fisheries Research InstituteEmail: lokasree@gmail.comMariculture is a promising fish producing industryin India with cage farming of marine finfish andshellfish becoming popular along the entire coast.Fish seed availability is the need of the hour forsustaining and supporting expansion of cage farmingof fishes in India. Capture Based Aquaculture (CBA),can be considered as an economic activity forfishermen communities to practise where byaccessing natural fish seed resources for culture, itenhances the fish production, yield and marketvalue. To undertake CBA as one of the maricultureactivity in India, it is necessary to understand theavailability of commercially important fish seedresources of Indian coast. Hence, a study wasto October. The nests are a shallow cup of twigs,creeper stems which is positioned in bushes inproximity to the water bodies. The other birdssighted in this area were cattle egret Bubulcus ibis,which chiefly feeds on grass hopper, other insects,frogs, lizards, fish etc., Kentish plover Charadriusalexandrinus which nests in sandy bed above thehigh tide mark in seashore or in dry river bed, Littleringed plover Charadrius dubius, Brown headed gullLarus brunnicephalus, black headed gull Larusridibundus and the Eurasian oyster catcherHaematopus ostralegus, which is a winter visitorto India.Conservation of these coastal buffer zones is ofprime importance for the preservation of manydiverse species of flora and fauna.  Urbanization inthese coastal buffer zones has led to peopledisposing off litter in these empty spaces whichobstructs the natural hydrodynamic flow and leadsto stagnation of water, eutrophication and breedingof mosquitoes.  When more sand dune in the beachesare transported elsewhere and less of marsh landsare available for the retention of rainfall, therecharge capacity of the  ground water table  isreduced, which in turn can lead to saline waterintrusion.  Population increase compels more peopleto depend on ground water for their daily need.These zones could be cleared of debris andmaintained as protected sites with a limited touristaccess. The study of the ecology of wetland birdsby identifying the patterns of use of habitat,breeding site and resources such as food will beuseful for designing strategies to conserve ourwetlands.Eurasian oyster catcher Haematopus ostralegus

Hydrodynamics of coastal wetlands in Dakshina Kannada and their importance

for avian fauna

http://eprints.cmfri.org.in/12076/1/MFIS_230_5.pdf

Hydrodynamics of coastal wetlands in Dakshina Kannada and their importance for avian fauna

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