Verdonk, J. (2015) Problems occurring during the transplantation of marine cultured Tridacna squamosa.

Verdonk, J. (2015) Problems occurring during the transplantation of marine cultured Tridacna squamosa. Bachlors thesis, Utrecht University. 10pp.

 

Summary

Coral reefs and their inhabitants are facing serious problems, threatening their very existence. One of the inhabitants with declining populations is Tridacna, the largest bivalve molluscs with the genus Tridacna gigas reaching lengths up to 1.4 meters being the largest and fastest growing in this family. Tridacna sp. are important habitants of the reef due to the fact that they provide shelter and food for other coral reef organisms, moreover their hard calcium carbonate shells are used by corals for substrate and are a way for the coral to venture out of the existing boundaries of the reef.

Giant clams are overfished for their meat and shells, however marine culturing of the giant clams has brought a change in the giant clam fishing industry. Detailed recruitment and nursery protocols have been established, artificial spawning can be induced and marine-culturing as well as land-culturing of giant clams is successful nowadays . This reduced the pressure on natural population greatly. Moreover with the marine-culturing of giant clams new possibilities for the conservation opened up; the so called gardening concept can be implemented with giant clams. This concept involves the marine-culture of organisms to a suitable transportation and releasing size.

This concept however has not been implemented successfully yet. Research for the restocking of Giant Clams started almost 20 years ago through the WorldFish Center and the Australian Centre For International Agricultural Research (ACIAR) (Gomez & Mingoa-Licuanan, 2006). Nevertheless a proper protocol is still lacking and much research is still needed to solve the occurring problems. The main problem at the moment is the fact that high mortality rates are common while restocking areas with marine cultured Tridacna squamosa. Due to the slow growth rate of 2-8 cm per year and high mortality rates might make the restocking of reefs with adult clams too costly and are thus unacceptable.

This study hence focuses on three different topics: firstly the impact of the enclosures on the constitutive and behavioral responds towards predators, secondly the impact of stress on the behavioral responds towards predators and lastly the natural distribution pattern of giant clams.

 

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Problems occurring during the transplantation of marine cultured Tridacna squamosa