Where do clonal coral larvae go? Adult genotypic diversity conflicts with reproductive effort in the brooding coral Pocillopora damicornis

Studi rekrutmen karang Pocillopora damicornis telah dilakukan dengan mengamati kerapatan juvenil pada substrat penempelan di dataran terumbu Pulau Panjang, Jepara, Jawa Tengah. Hasil menunjukkan bahwa rekrutmen terjadi sepanjang tahun dan tertinggi pada periode Agustus-Oktober. Laju rekrutmen karang di belakang terumbu (back reef) pada sisi bawah angin (selatan) lebih tinggi daripada di sisi atas angin (utara) Pulau Panjang, tampaknya hal ini berkorelasi dengan kerapatan populasi karang dewasanya. Kerapatan juvenil karang tertinggi pada substrat batu alam terjadi pada sisi bawah permukaan substrat, akan tetapi pertumbuhan juvenil karang tertinggi ditemukan di sisi atas permukaan substrat. Hal ini mengindikasikan bahwa kerapatan juvenil karang berhubungan dengan kelulusan hidup juvenil karang. Semakin tinggi kerapatan juvenil karang P. damicornis maka semakin rendah kelulusan hidup juvenil karang karena terjadinya peningkatan persaingan sesama juvenil karang dan akibat kekurangan cahaya. Kata kunci: rekrutmen, kerapatan, kelulushidupan, karang Pocillopora damicornis Recruitment of the brooding coral Pocillopora damicornis was studied by observing the juvenile density on the settlement plate substrate in reef flat of Panjang Island, Jepara, Central Java. The results show that recruitment occurs throughout the year and the highest in the period from August to October. The rate of recruitment of coral reefs in back reef on the leeward (south) is higher than on the windward (north) of the island, it seems to be correlated with population density of adult corals. The highest density of juvenile corals on natural substrata occurs on the lower side surface of the substrate, but the highest growth of juvenile are found on the upper side surface of the substrate. This indicates that the density of juvenile corals associated with the survival of juvenile corals. The higher density of juvenile corals P. damicornis, the lower the survival of juvenile corals due to an increase in competition among juvenile corals and due to lack of light. Keywords: recruitment, density, survivorship, coral Pocillopora damicornis

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Nutrient gradients simulate different adjustments of coral-algal symbiosis

10.21203/rs.3.rs-17147/v1 ◽

2020 ◽

Author(s):

Haoya Tong ◽

Guowei Zhou ◽

Fang Zhang ◽

Jin Sun ◽

Weipeng Zhang ◽

...

Keyword(s):

Nitrogen Metabolism ◽

Atp Synthesis ◽

Pocillopora Damicornis ◽

Material Transport ◽

Coral Larvae ◽

Coral Larva ◽

Algal Symbiosis ◽

Energy Synthesis ◽

Coral Reef Degradation ◽

Transcriptomic Responses

Abstract Background: Eutrophication is one of the major causes of coral reef degradation but the effect of eutrophication on coral and its symbiont algae remains unclear, particularly for the larval stage of coral. In the present study, the physiological and transcriptomic responses of the larvae of an ecologically important scleractinian coral Pocillopora damicornis were analyzed after a 5-day exposure to elevated nitrate in order to assess the survival and adaptation of coral-algal symbiosis under elevated nutrients. Results: The results showed that multiple larval transcripts were significantly correlated with Symbiodiniaceae transcripts. The major differentially expressed transcripts in coral/Symbiodiniaceae included those responsible for energy synthesis/comsumption, nitrogen metabolism and stressor response. Slightly elevated nitrate concentration could in fact promote the health of coral meta-organism. With increase in nitrate concentrations, coral larvae showed significant stress response to maintain the coral-algal symbiosis and coral-algal symbiosis was impaired, while Symbiodiniaceae switched photosynthetic states for ATP synthesis, material transport and nitrogen metabolism for symbiosis maintenance under the control of the coral hosts.Conclusions: Our results suggest that adjustment of coral-algal symbiosis via coral control and a shift in Symbiodiniaceae photosynthetic states serves as the basis of coral meta-organism adaptation under eutrophication stresses. The larvae of P. damicornis and Symbiodiniaceae displayed different transcriptomic responses to nitrate enrichment. Coral larva meta-organism can adapt to moderately elevated nutrient concentration while extreme eutrophication can impair coral-algal symbiosis and affect coral larvae survival ultimately.

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