scholarly journals Giant clam growth in the Gulf of Aqaba is accelerated compared to fossil populations

2021 ◽  
Vol 288 (1957) ◽  
pp. 20210991
Author(s):  
Daniel Killam ◽  
Tariq Al-Najjar ◽  
Matthew Clapham
Keyword(s):  
Aerosol Deposition ◽  
Gulf Of Aqaba ◽  
Giant Clam ◽  
Daily Growth ◽  
Giant Clams ◽  
Winter Temperatures ◽  
Tridacna Maxima ◽  
Modern Era ◽  
Northern Red Sea ◽  
Nitrate Fertilization

The health of reef-building corals has declined due to climate change and pollution. However, less is known about whether giant clams, reef-dwelling bivalves with a photosymbiotic partnership similar to that found in reef-building corals, are also threatened by environmental degradation. To compare giant clam health against a prehistoric baseline, we collected fossil and modern Tridacna shells from the Gulf of Aqaba, Northern Red Sea. After calibrating daily/twice-daily growth lines from the outer shell layer, we determined that modern individuals of all three species ( Tridacna maxima , T. squamosa and T. squamosina ) grew faster than Holocene and Pleistocene specimens. Modern specimens also show median shell organic δ 15 N values 4.2‰ lower than fossil specimens, which we propose is most likely due to increased deposition of isotopically light nitrate aerosols in the modern era. Nitrate fertilization accelerates growth in cultured Tridacna , so nitrate aerosol deposition may contribute to faster growth in modern wild populations. Furthermore, colder winter temperatures and past summer monsoons may have depressed fossil giant clam growth. Giant clams can serve as sentinels of reef environmental change, both to determine their individual health and the health of the reefs they inhabit.

scholarly journals Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>

2019 ◽  
Vol 16 (13) ◽  
pp. 2635-2650 ◽  
Author(s):  
Susann Rossbach ◽  
Vincent Saderne ◽  
Andrea Anton ◽  
Carlos M. Duarte
Keyword(s):  
Primary Production ◽  
Red Sea ◽  
Gross Primary Production ◽  
Dry Mass ◽  
Giant Clam ◽  
Light Levels ◽  
Unicellular Algae ◽  
Giant Clams ◽  
Intermediate Size ◽  
Tridacna Maxima

Abstract. Tropical giant clams of the subfamily Tridacninae, including the species Tridacna maxima, are unique among bivalves as they live in a symbiotic relationship with unicellular algae and generally function as net photoautotrophs. Light is therefore crucial for these species to thrive. Here we examine the light dependency of calcification rates of T. maxima in the central Red Sea as well as the patterns of its abundance with depth in the field. Red Sea T. maxima show the highest densities at a depth of 3 m with 0.82±0.21 and 0.11±0.03 individuals m−2 (mean ± SE) at sheltered and exposed sites, respectively. Experimental assessment of net calcification (µmol CaCO3 cm−2 h−1) and gross primary production (µmol O2 cm−2 h−1) under seven light levels (1061, 959, 561, 530, 358, 244, and 197 µmol quanta m−2 s−1) showed net calcification rates to be significantly enhanced under light intensities corresponding to a water depth of 4 m (0.65±0.03 µmol CaCO3 cm−2 h−1; mean ± SE), while gross primary production was 2.06±0.24 µmol O2 cm−2 h−1 (mean ± SE). We found a quadratic relationship between net calcification and tissue dry mass (DM in gram), with clams of an intermediate size (about 15 g DM) showing the highest calcification. Our results show that the Red Sea giant clam T. maxima stands out among bivalves as a remarkable calcifier, displaying calcification rates comparable to other tropical photosymbiotic reef organisms such as corals.

scholarly journals Drivers of the Abundance of Tridacna spp. Giant Clams in the Red Sea

2021 ◽  
Vol 7 ◽  
Author(s):  
Susann Rossbach ◽  
Andrea Anton ◽  
Carlos M. Duarte
Keyword(s):  
Red Sea ◽  
Large Scale ◽  
Multiple Roles ◽  
Giant Clam ◽  
Carbonate Budget ◽  
Giant Clams ◽  
Tridacna Squamosa ◽  
Tridacna Maxima ◽  
Large Scale Survey ◽  
Reef Zone

Giant clams (Subfamily Tridacninae), are important members of Indo-Pacific coral reefs, playing multiple roles in the framework of these communities. Although they are prominent species in Red Sea reefs, data on their distribution and densities in the region are scarce. The present study provides the first large-scale survey of Red Sea Tridacna spp. densities, where we examined a large proportion of the Saudi Arabian Red Sea coast (1,300 km; from 18° to 29°N). Overall, Tridacninae were found at densities of 0.19 ± 0.43 individuals m–2 (±SD). Out of the total 4,002 observed clams, the majority (89%) were Tridacna maxima, with 0.17 ± 0.37 individuals m–2, while only 11% were Tridacna squamosa clams with 0.02 ± 0.07 individuals m–2. We also report on a few (total 6) Tridacna squamosina specimens, found at a single reef. We identified different geographical parameters (i.e., latitude and distance to shore) and local environmental factors (i.e., depth and reef zone) as the main drivers for local Tridacna spp. densities. Our results show that the drivers influencing the densities of Red Sea giant clams are complex due to their co-occurrence and that this complexity might explain the high variation in Tridacninae abundances across the Indo-Pacific, but also within a given reef. We also estimate that giant clam calcification likely contributes to an average of 0.7%, but potentially up to 9%, of the overall mean calcium carbonate budget of Red Sea coral reef communities.

scholarly journals Light-dependent calcification in Red Sea giant clam <i>Tridacna maxima</i>

2019 ◽  
Author(s):  
Susann Rossbach ◽  
Vincent Saderne ◽  
Andrea Anton ◽  
Carlos M. Duarte
Keyword(s):  
Primary Production ◽  
Red Sea ◽  
Gross Primary Production ◽  
Dry Mass ◽  
Giant Clam ◽  
Light Levels ◽  
Unicellular Algae ◽  
Giant Clams ◽  
Intermediate Size ◽  
Tridacna Maxima

Abstract. Tropical giant clams of the Tridacninae family, including the species Tridacna maxima, are unique among bivalves as they live in a symbiotic relationship with unicellular algae and generally function as net photoautotrophic. Light is therefore crucial for these species to thrive. Here we examine the light-dependency of calcification rates of T. maxima in the Central Red Sea as well as the patterns of its abundance with depth in the field. Red Sea T. maxima show highest densities in a depth of 3 m with 0.82 ± 0.21 and 0.11 ±  0.03 individuals m−2 (mean ± SE) at sheltered and exposed sites, respectively. Experimental assessment of net calcification (μmol CaCO3 cm−2 h−1) and gross primary production (μmol O2 cm−2 h−1) under seven light levels (1061, 959, 561, 530, 358, 244 and 197 μmol quanta m−2 s−1) showed net calcification rates to be significantly enhanced under light intensities corresponding to a water depth of 4 m (0.65 ± 0.03 μmol CaCO3 cm−2 h−1; mean ± SE), while gross primary production was 2.06 ± 0.24 μmol O2 cm−2 h−1 (mean ± SE). We found a quadratic relationship between net calcification and tissue dry-mass (DM in gram), with clams of an intermediate size (about 15 g DM), showing the highest calcification. Our results show that the Red Sea giant clam T. maxima stands out among bivalves as a remarkable calcifier, displaying calcification rates comparable to other tropical photosymbiotic reef organism, such as corals.

scholarly journals KEPADATAN DAN KONDISI HABITAT KERANG KIMA (CARDIIDAE: TRIDACNINAE) DI BEBERAPA LOKASI DI PERAIRAN SULAWESI UTARA

2017 ◽  
Vol 3 (2) ◽  
pp. 139
Author(s):  
Ucu Yanu Arbi
Keyword(s):  
Large Scale ◽  
Data Retrieval ◽  
Line Transect ◽  
Giant Clam ◽  
North Sulawesi ◽  
Giant Clams ◽  
Tridacna Squamosa ◽  
Tridacna Maxima ◽  
Tridacna Gigas ◽  
Tridacna Crocea

Kima merupakan salah satu jenis kerang laut yang telah dieksploitasi oleh nelayan Sulawesi Utara dalam skala besar karena memiliki nilai ekonomis yang tinggi. Penelitian ini bertujuan untuk mengetahui kepadatan dan kondisi habitat kerang kima di perairan Sulawesi Utara pada tahun 2007-2009. Daerah penelitian ini meliputi perairan Bitung, Pulau Lembeh, Taman Nasional Bunaken, Likupang, Pulau Talise, Kepulauan Sangihe, dan Kepulauan Talaud. Pengambilan data dilakukandengan metode rapid reef resources inventory dan metode kuadrat transek garis. Ditemukan 1.064 individu kima yang terdiri atas tujuh jenis, yaitu Tridacna crocea, Tridacna squamosa, Tridacna maxima, Tridacna derasa, Tridacna gigas, Hippopus hippopus, dan Hippopus porcelanus. Kepadatan kimasecara keseluruhan di lokasi penelitian rata-rata 0,53 ind./m2. Kepadatan tertinggi adalah jenis Tridacna crocea (rata-rata 0,32 ind./m2), sedangkan terendah adalah jenis Tridacna gigas, Tridacna derasa, dan Hippopus porcelanus (0,01 ind./m2). Giant clam is one of the sea shells that have been exploited by the fisherman of North Sulawesi, a large scale because it has a high economic value. This study aims to determine the distribution and density of giant clams in North Sulawesi waters in 2007-2009. Research conducted in the waters of Bitung, Pulau Lembeh, Bunaken National Park, Likupang, Talise Island, Sangihe Islands, and Talaud Islands. Data retrieval is done by the rapid reef resources inventory method and the quadrat line transect method. 1.064 individual of giant clams was found consisting of seven species, there are Tridacna crocea, Tridacna squamosa, Tridacna maxima, Tridacna derasa, Tridacna gigas, Hippopus hippopus and Hippopus porcelanus. Density of giant clams density is 0,53 ind./m2. The highest density of individuals is Tridacna crocea (0,32 ind./m2), while the lowest is Tridacna gigas, Tridacna derasa and Hippopus porcelanus (0.01 ind./m2).

scholarly journals Tissue-Specific Microbiomes of the Red Sea Giant Clam Tridacna maxima Highlight Differential Abundance of Endozoicomonadaceae

2019 ◽  
Vol 10 ◽  
Author(s):  
Susann Rossbach ◽  
Anny Cardenas ◽  
Gabriela Perna ◽  
Carlos M. Duarte ◽  
Christian R. Voolstra
Keyword(s):  
Red Sea ◽  
Giant Clam ◽  
Differential Abundance ◽  
Tissue Specific ◽  
Tridacna Maxima

scholarly journals Scorpaena decemradiata new species (Teleostei: Scorpaenidae) from the Gulf of Aqaba, northern Red Sea, a species distinct from Scorpaena porcus

2018 ◽  
Vol 82 (3) ◽  
pp. 169
Author(s):  
Ronald Fricke ◽  
Daniel Golani ◽  
Brenda Appelbaum-Golani ◽  
Uwe Zajonz
Keyword(s):  
New Species ◽  
Red Sea ◽  
Gulf Of Aqaba ◽  
Pectoral Fin ◽  
Dorsal Fin ◽  
Lower Jaw ◽  
Fin Ray ◽  
Fin Rays ◽  
Northern Red Sea ◽  
Scorpaena Porcus

The scorpionfish Scorpaena decemradiata n. sp. is described from off the coast of Israel in the Gulf of Aqaba, northern Red Sea. The new species is similar to S. porcus Linnaeus, 1758, but is characterized by dorsal fin spines XII, soft dorsal fin rays 10 (the last divided at base); pectoral fin rays 16, uppermost branched pectoral fin ray is the second; lacrimal with 2 spines over maxilla that point at nearly right angle from each other, the posterior pointing ventrally and slightly anteriorly; occipital pit well developed; anteriormost mandibular lateral-line pores small, separated; scales ctenoid; 59-62 scale rows in longitudinal series; scales absent on chest and pectoral fin base; and cirri developed over entire head and body, but no cirri on lower jaw. An updated checklist of the species of the genus Scorpaena Linnaeus, 1758 and a key to the species of the eastern Atlantic, Mediterranean Sea and Red Sea are presented.

scholarly journals Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

Microbiome ◽  
2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Isis Guibert ◽  
Gael Lecellier ◽  
Gergely Torda ◽  
Xavier Pochon ◽  
Véronique Berteaux-Lecellier
Keyword(s):  
Giant Clam ◽  
Tridacna Maxima
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