Sea polo-necks are distributed throughout the tropical and semitropical seas. They have a complex history, with juveniles and immature phases switching scrounging home grounds and grownup females executing long distance genteelness migrations ( Mazaris et al. , 2008 ) . In coastal and marine ecosystem, sea polo-necks have as of import function as a anchor species that transportation food and energy from the ocean to the land at nesting beaches when they deposit their eggs, and they affect the construction and operation of scrounging home grounds such as coral reefs, sea grass hayfields, algal beds, and soft substrate sea underside ( SWOT, 2006 ) .
Sea polo-necks select a nest site by make up one’s minding where to emerge from the breaker and where on the beach to set their eggs ( Witherington and Marti, 1996 ) . However, this is still bad in order to take to nest on some beaches and non others ( Van meter, 1992 ) . For case, In Japan, an analysis of nesting beaches revealed that factors impacting beach choice by polo-necks included softness of the sand and beach length ( Kikukawa et al.
, 1999 ) , while in the Mediterranean Loggerhead sea polo-neck emerge chiefly on beaches that are fronted by preponderantly flaxen countries ( Le Vin et al. , 1998 ) . Other factors that influence nesting site choice by sea polo-neck are flora screen, distance to flora, humidness, temperature of the sand, and distance to high tide line ( Kamel and Mrosovsky, 2004 ; Karavas et al. , 2005 ; Mazaris et al. , 2006 ; Pike, 2008 ) .
Sea grass is one of the most widespread coastal flora types in the universe. It protects shorelines against eroding in the center and lower intertidal and bomber tidal zones, because of their gregarious growing and heavy root systems ( Dahdouh-Guebas et al. , 2006 ) . They are besides known to roll up and stabilise deposits from the environing environment ( Fry et al. , 1983 ) . Sea grass beds are besides of import because they provide engendering and development evidences for many species of fish, shelfish and crustaceans ( Cccturtle.org, 2009 ) , scrounging land for herbivores ( Musick and Limpus 1997 ) and attachment sites to little macroalgae and epiphytic beings such as sponges, polyzoans, forams, and other taxa that use sea grasses as home ground ( SMS.si.edu, 2009 )
So far, there is no research has been done to see what is the relationship occurred between the Loggerhead sea polo-neck and presence of sea grass. This could be an interesting inquiry to reply the wonder of research worker about nesting behavior of this species.
Distribution and Nesting Ecology
Loggerhead sea polo-necks are circumglobal, happening throughout the temperate and tropical parts of the Atlantic, Pacific, and Indian Oceans ( NOAA-Fisheries. , 2009 ) . They are besides extremely migratory, capable of going 100s to 1000s of kilometers between scrounging and engendering countries. Female Dunce does non look to migrate to merely one scrounging country. Rather, they move continuously and therefore look to scrounge at a series of coastal countries. Furthermore, females migrate to nest at their natal beaches about every 3 old ages ( Plotkin, 1997 )
In Mediterranean, the of import nesting sites of Loggerhead sea polo-necks are found in Greece, Turkey and Cyprus ( Margaritoulis et al. , 2003 ) , while others nesting sites with lower denseness are found in Syria ( Kasparek, 1995 ) , Tunisia ( Laurent et al.,1990 ) and Israel ( Kuller, 1999 ) . For Greece, nesting Loggerhead are significantly smaller that those other parts of the universe ( Margaritoulis et al. , 2003 ) . Following nesting informations from several seasons, Margaritoulis ( 2000 ) classified nesting countries in Greece as “ major ” or “ moderate ” . “ Major ” nesting countries are those hosting on norm more than 100 nests/season and over 6 nests/km/season. Merely five countries in Greece fulfil the demands for “ major ” countries, there are: Laganas Bay ( Zakynthos island ) , Kyparissia Bay ( western Peloponnesus ) , Rethymno ( Crete ) , Lakonikos Bay ( southern Peloponnesus ) and the Bay of Chania ( Crete island ) ( Margaritoulis, 2000 ) .
Loggerhead nesting in Greece is extremely seasonal. The nesting season normally extends from terminal of May to late August ( Margaritoulis and Rees, 2001 ) . Nesting success varied from country to country, by and large caused by diverseness of nesting home ground ( Table 1-1 ) .
Table 1aˆ‘ . The chief nesting countries monitored during 2002 in Greece
Beach length ( kilometer )
Number of outgrowths
Number of nest
Overall nesting success ( % )
Nesting Density ( nest/km )
Laganas Bay ( Zakynthos )
Southern Kyparissia Bay
Bay of Chania
Bay of Messara
Beginnings: Margaritoulis and Rees ( 2003 )
Feeding and Diving Behaviour
Loggerhead sea polo-necks are known as a carnivorous, scrounging chiefly on benthal invertebrates throughout their distribution scope. Loggerhead populations from different geographic locations forage on different types of quarry, and the list of the types of quarry eaten by Loggerhead in the natural state is extended. The high diverseness in the types of their quarry demonstrates versatility in scrounging behavior, proposing that the Loggerhead is a Renaissance man ( Plotkin, et al. , 1993 ) .
Dodd ( 1988 ) stated that this species eats a assortment of nutrients for each phase. Juvenile Loggerhead peculiarly feed on cnidarians while sub grownup and grownup provender on jelly fish but they are chiefly feeder on benthal invertebrates. He besides mentioned that Loggerhead take alga on occasion, possibly consuming it while feeding invertebrates. Table 2 shows diet penchant of Loggerhead sea polo-necks.
Table 1aˆ‘ . Diet penchant Loggerhead sea polo-necks ( Carreta carreta )
4.0 – 5.6 centimeter ( SCL )
Cnidaria, Tar, Synthetics, Sargassum, Crustacean, Hydrozoans, Insects, Gastropods, Plant Material
Atlantic, away at sea
4.5 -47 centimeter ( CL )
Sargassum, Plant stuff, Insects, Crustacean, Cnidaria, Tar, Fish eggs, Plastics/synthetics
4.1 – 7.8 centimeter ( SCL )
Sargassum, Plant Material, Cnidaria, Copepods, Insects, Plastics & A ; Tar, Polycheates, Bryozoan
Sargassum, Gastropods, Crustacean
13.5 – 74.0 centimeter ( CCL )
Gastropods, Cephalopods, Crustaceans, Cnidaria, rochordata, Fish, Annelids, Algae
Average 61.4 centimeter ( SCL )
Pleuroncodes planipes – Pelagic crab
4.6 – 10.6 centimeter ( CCL )
Synthetics, Cnidaria, Crustacea, Gastropods, Plant Material
From assorted beginnings. Summarized by Boyle and Limpus, 2008
Diving plays a cardinal function in the lives of all air-breathing Marine craniates, including sea polo-neck ( Rice and Balazs, 2008 ) and it is influenced by organic structure size ( Schreer and Kovacs, 1997 ) . ( 2004 ) reported that the younger of Chelonian mydas ( 8-10 hebdomads of development period ) honkytonks were normally shallow ( a‰¤ 6 m ) and consisted of three ( V, S, U ) profiles. The older can plunge merely somewhat deeper than the younger. In contrast, grownup can plunge in surplus of 100 – 135 m ( Rice and Balazs, 2008 ) . Margaritoulis and Teneketzis ( 2001 ) reported that most of dunce were captured in Lakonikos Bay, Greece are dominated in 18 meters deepness.
Oceanic Loggerhead spend 75 % of the clip in the top of H2O column ; 80 % of honkytonks are 2-5 metre, and reminder of the honkytonks are distributed throughout the top 100 m. Occasionally this species can plunge greater than 200 m ( Bolton and Rieward, unpubl.data ) . In general, little size should restrict plunging deepness and continuance because of volume of tissue to hive away O is lower and mass specific metabolic rates of smaller animate being are higher ( Schmidt-Nielsen, 1997 ) .
The most of import nesting sites of the Loggerhead in the Mediterranean are located in Greece. The sites are dispersed along Greece ‘s western and southern seashore line and on Crete Island ( Margaritoulis et al. , 2003 ) . However, the population of the Loggerhead in Greece is declined quickly in the last decennary. Human activities such as fishing force per unit area, coastal development, extended urban enlargement for touristry and diversion, are the most factors that act uponing in decreasing of figure of this species ( Arianoutsou, 1988 ; Margaritoulis et al. , 2003 ) .
Loggerhead sea polo-necks ( Caretta Caretta ) have defined as endanger species in the universe By IUCN. Therefore, many international pacts and understanding have been set up to protect the being of this species ( NOAA-Fisheries. , 2009 ) . Many surveies have been done in order to understand nesting habitat suitableness standards, but they are seldom reach consolidation ( Miller et al. , 2003 ) and chiefly focused on the nesting beaches, and take less attending on non nesting beaches that are comparative nearby. Knowing that sea turtle spend most of their life in the Marine environment, understanding how they interact in their environment is one of of import factor for measuring habitat suitableness and can take to heighten successful of direction determination and preservation schemes.
The chief aim of this survey is to look into the relationship between sea grass and nesting sites choice by Loggerhead sea polo-necks ( Caretta Caretta ) in Crete, Greece.
To qualify per centum screen of sea grass as a parametric quantity to find nesting site choice by Loggerhead sea polo-necks ( Caretta Caretta ) .
a. What are the differences between coastal physical parametric quantities in nesting beaches and non-nesting beaches?
B. Which are the of import coastal physical parametric quantities that are more correlative with the nesting home ground of the Loggerhead sea polo-neck?
Can the per centum screen of sea grass be confirmed as an index to find sea turtle nesting site choice?
H10: The coastal physical parametric quantities do non hold a important difference in nesting beaches and non-nesting beaches.
H11: The coastal physical parametric quantities do hold a important difference in nesting beaches and non-nesting beaches.
H20: There are no coastal physical parametric quantities that are significantly of import to nesting home ground of Loggerhead sea polo-neck.
H21: There are coastal physical parametric quantities that are significantly of import to nesting home ground of Loggerhead sea polo-neck.
H30: There is no association between per centum screen of sea grass and the figure of nests.
H31: There is a negative association between per centum screen of sea grass and the figure of nests.
Material and Methods
Crete is the largest island in Greece and the 2nd biggest ( after Cyprus ) of the east Mediterranean ( Figure 2-1 ) . It lies at the southern Aegean Sea ( 23A°31 ‘ to 26A°18 ‘ Tocopherol and from 34A°55 ‘ to 35A°41’N ) and at the hamlets of three continents Europe, Asia and Africa. Crete covers an country of 8,336 km2, with a length of 260 kilometers, and a breadth that from 12 to 60 kilometer. The entire length of the Cretan coastline is 1046 kilometer and consists of both flaxen beaches and bouldery shores ( West-Crete, 2008 ) .
Figure 2.1aˆ‘ Map of Crete Island, Greece.
Administratively, Crete is one of the 13 parts of Greece and is divided to four prefectures ( Hania, Rethymnon, Heraklion and Lassithi ) and 70 municipalities. The population of the island is about 630.000 ( 2005 ) , and over a 3rd of it is found in the three major metropoliss, Iraklion ( ~150.000 ) , Hania ( ~50.000 ) and Rethymnon ( ~30.000 ) located on the north seashore of the island ( Interkriti.org, 2009 ) .
Crete was chosen as a survey country because of this island has been categorized as one of of import nesting sites for Loggerhead sea polo-neck in the Mediterranean. There are 3 countries that were indicated as chief nesting sites in Crete i.e Rethimnon, Hania and Messara ( Margaritoulis and Rees, 2003 ) .
In the Mediterranean Sea, Posidonia Oceania is the dominant endemic sea grass and its hayfields are considered as one of the most of import and productive ecosystems in coastal Waterss. It covering the sea bed from the surface down to about 40 m ( Montefalcone et al. , 2008 ) .
Figure 2.2aˆ‘ . Research Scheme
In situ informations aggregation
Fieldwork was carried out from September 28th to October 18th. The informations were collected includes the information about nesting beaches, not nesting beaches, and presence/absence of sea grass. Most of the beaches was been visited in this survey are based on the information from the old survey ( Asaad, 2009 ) . There are 4 extra sample points that have been added in this survey. All of point observations are presented in Table 2-1.
Table 2aˆ‘ . Point of Observations
Sea grass Presence/Absence
Vai ( Palm Beach )
1: Asaad ( 2009 ) ; 2: This survey
* : It was indicated as non-nesting sites
Datas from Natura 2000 were used to turn up sea grass presence. There are 6 countries covered by Natura 2000 undertaking in Crete i.e Setia, Zakros, Rethimnon bay, Kissamos, Paleohora, and Elafonissos ( Figure 2-2 ) . The methods that are used to roll up the sand samples are based on Asaad, ( 2009 ) . The sand samples were taken merely for new nesting and non-nesting beaches.
Cover fraction of sea grass are identified based on still images taken along the sea grass country utilizing transect trying method. The exposures are captured utilizing an submerged camera, Olympus ST 8000 at 4 proceedingss interval from gum elastic boat along the transect line. The camera and GPS were attached to the chromium steel stick. The leveler was used to maintain the place of the camera when submerged in saltwater. The clip cast of the GPS place and of the exposure allowed the geolocation of each exposure.
Figure 2.3aˆ‘ . Map of Observation points in Crete Island, Greece
Percentage screen of sea grass
Image stitchingA orA exposure stitchingA is the technique of uniting numerousA imagesA with overlapping Fieldss of position to bring forth a segmentedA panoramaA or high-resolution image ( Wikipedia, 2009 ) . It is performed through autostitch Panorama package was used to acquire the usage ofA computing machine package, most attacks to image sewing require about exact convergences between images and indistinguishable exposures to bring forth seamless consequences. It is besides known asA mosaicing ( M. Brown et al. , 2003 ) .
Sand Samples Analysis
Sand samples were analysed at ITC research lab for 7 parametric quantities of beach features i.e pH, conduction content, grain form, grain cleanliness, Sodium Chloride ( NaCl ) content, Calcium Carbonate ( CaCO3 ) content, and grain size. All methods in this analysis are following methods which is done by ( 2009 ) .
The statistical analyses were used in this survey are concentrating on determine the difference in value of each coastal parametric quantities in both nesting and non-nesting, the designation of the relationship between sea grass presence and nesting happening, to find the parametric quantities that are correlated with nesting activity, and the designation of the relationship between per centum screen of sea grass and figure of nest. All of the analyses were done utilizing SPSS 16.
Each parametric quantity is tested utilizing independent t-test and chi-square important trials. The relationship between per centum screen of sea grass and figure of nest is tested utilizing a correlativity trial. The independent t-test is used to see the important difference between the agencies of uninterrupted variable of two groups on some independent variable where those two groups are independent of one another. Nesting and non-nesting beaches are independent variables of two groups while the other independent variables are pH, conduction, NaCl content, CaCO3 content, and figure of nest. The other variables, sand grain form and sand cleanliness are tested utilizing a qi square trial.
The factor that extremely correlated to suitable nesting beaches is tested utilizing a logistic arrested development. To find whether the coastal parametric quantities are influenced to handiness of se grass, a multiple additive arrested development was used, normalized in order to relieve the influences of the said parametric quantities therefore the increasing the variableness of the handiness of sea grass utilizing Multiple Linear arrested development.
A sum of 7 parametric quantities were analysed for sand features in ITC research lab i.e pH, conduction content, grain form, grain cleanliness, Sodium Chloride ( NaCl ) content, Calsium Carbonate ( CaCO3 ) content, and grain size. All of this informations are presented in Appendix.
( B )
( a )
( degree Celsius )
Figure 3.1aˆ‘ . Comparison of pH fluctuations of the sand in non-nesting beaches and nesting beaches. A. This survey, B. Asaad ( 2009 ) , and C. All
( a )
( B )
( degree Celsius )
Figure 3.1aˆ‘ . Comparison of conduction fluctuations ( AµS/cm ) of the sand in non-nesting beaches and nesting beaches. A. This survey, B. Asaad ( 2009 ) , and C. All
( B )
( a )
( degree Celsius )
Figure 3.1aˆ‘ . Comparison of NaCl content fluctuations ( ppm ) of the sand in non-nesting beaches and nesting beaches. A. This survey, B. Asaad ( 2009 ) , and C. All
Figure 3.1aˆ‘ . Comparison of three major grain size of the sand in non-nesting beaches and nesting beaches. A. This survey, B. Asaad ( 2009 ) , and C. All
( a )
( B )
( degree Celsius )
Figure 3.1aˆ‘ . Comparison of grain form of the sand in non-nesting beaches and nesting beaches. A. This survey, B. Asaad ( 2009 ) , and C. All
Figure 3.1aˆ‘ . Comparison of grain cleanliness of the sand in non-nesting beaches and nesting beaches. A. This survey, B. Asaad ( 2009 ) , and C. All
Sea grass presence and nesting happening
Figure 3.2aˆ‘ . The relationship between sea grass presence/absence and figure of nest.
Precentage screen of sea grass
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