Crassostrea rhizophorae

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Crassostrea rhizophorae
Crassostrea rhizophorae 000.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Ostreida
Family: Ostreidae
Genus: Crassostrea
Species:
C. rhizophorae
Binomial name
Crassostrea rhizophorae
(Guilding, 1828)

Crassostrea rhizophorae, also known as the mangrove cupped oyster, is a species of bivalve in the family Ostreidae. [1] [2] C. rhizophorae is one of the predominant oyster species in the South Atlantic, specifically in Central and South America. [1] [3] It is often found in the vast mangrove ecosystem along the coast of Brazil. [1]

Contents

Environment

C. rhizophorae is typically found in the intertidal or shallow subtidal regions of tropical mangroves and other estuarine regions. The optimal vertical range for C. rhizophorae is between 1.0 m and 1.5 m above the 0.0 m level of spring tides. [4] At greater depths, the substrate is too soft for the oysters to settle and the pressure from predators like crabs and fish is too extreme. [5] [4] Above 1.5 m, C. rhizophorae will not settle due to extensive exposure time. [4] Due to the narrow vertical band that C. rhizophorae inhabits, species survive best when securely fixed on rocks, hard substrates, and on mangrove roots, such as the aerial roots of the red mangrove ( Rhizophora mangle ). [5] Like most oysters, C. rhizophorae tend for form clusters of individuals which may develop into oyster reefs.

The optimal salinity range for C. rhizophorae is approximately 7.2 to 28.8‰, however, it can tolerate significant salinity fluctuations of short duration, which are experienced in Central and South America during the rainy seasons. [4] C. rhizophorae thrives best in temperatures below 30 °C (86 °F). While it is able to withstand fluctuations, very few larvae are found at temperatures exceeding 30 °C. [4]

Characteristics

C. rhizophorae is often called the Caribbean or mangrove oyster due to the environment that it is found in. This species of oysters is an oviparous species, which indicates that they are animals that reproduce by laying their eggs without much embryonic development within the mother. C. rhizophorae, and more generally the genus, Crassostrea, are cup-like, or cupped, oysters, meaning that the shell itself has a cup shape to it. [4]

C. rhizophorae has a promyal chamber and small ostia. [4] [5] The oyster also has a thin, foliaceous, deeply cupped right valve and the upper left valve is small and flat, which enables it to fit into the lower one. The beak is twisted dorsally, and the muscle scar is near the dorsal margin of the shell. The muscle scar is often unpigmented. [4]

Adult C. rhizophorae can reach up to 10 cm in height. However, in their natural environment, their growth is stunted, leading to a maximum height of 5 cm. [4]

Diet

C. rhizophorae tend to consume any microscopic particles that are carried in suspension in the water, regardless of their nutritional value. They consume a great range of organisms belonging to the following groups: Cyanobacteria, Xanthophyta, Bacillariophyta, Dinophyta, Euglenophyta, Chlorophyta, Protozoa, Rotifera, Annelida, Arthropoda, and Mollusca. C. rhizophorae have also been shown to consume fragments of Phytoplankton, Zooplankton, and Phanerogamae and grains of sediment. A study found that Bacillariophyta was the dominant group of consumption by C. rhizophorae at 63% of the food content in the stomach, followed by Chlorophyta at 12% of the food content in the stomach. [6] This study also looked at the percentage of food items in the stomach contents. They categorized certain amounts of food as "full", "almost full", "almost empty", and "empty". 57% of the individuals were categorized as being in the full stage, which suggests the existence of good availability of food for C. rhizophorae in the environment that they are in. [6]

Reproduction and growth

Reproduction

C. rhizophorae have primary bisexual gonads that form associations of cells in the connective tissue anterior to the heart by the time they reach 0.7 cm or 45 days after setting. The gonada has cells for both sexes but this is shown the most with spermatogenesis cells in 90% of animals that are sexually mature before reaching 2.0 cm or 120 days after setting. In older individuals ranging from 6 to 18 months and 4 to 6 cm in size, 83.5% were females so most change happened between 2 and 4 cm in size, yet only 0.5% are hermaphrodictic. [4] The active gonad goes through prematuration and maturation stage before spawning and then after partial spawning, the gonad enters a recuperation stage. During this stage, the gametogenesis starts a new maturation that leads to the complete cytolysis of the gamete and obliteration of the follicles. Most adult oysters ranging from 4 to 6 cm in length become mature without an undifferentiated stage after the spawning or resting stage. [4]

Due to the constant high water temperature, gametogenesis happens twice during the year, March and October. These peaks happen when drastic changes in salinity, rainy periods, but intense rains like 150 mm per week depress spawning. [5] If done in the lab, C. rhizophorae embryonic development can be done in 24 hours at a density of to ovocyte per liter when fertilized at concentrations of 500 to 5000 spermatozoans per ovocyte. From this it was determined that the best range of salinities for embryonic development is 25% to 37% and the best temperatures are around 25 but below 30 degrees Celsius. [4]  

Growth

C. rhizophorae can grow in a variety of locations, but grow best in the roots of mangroves. C. rhizophorae tend to grow to 4 to 7 cm in length, and it can take up to 18 months for most members of the species to reach their full size. The maximum size of C. rhizophorae is approximately 7 to 8 cm. [4] Adult C. rhizophorae can reach up to 10 cm in height. However, in their natural environment, their growth is stunted, leading to a maximum height of 5 cm. [4]

C. rhizophorae begin their life as floating larvae, which soon settle onto a solid substrate. Once settled onto their substrate, the growing oysters are known as spat. Spat grow 1 cm a month for the first 3 months and then growth rates slow to an approximate growth of 0.78 cm a month. [5] After reaching 6.5 cm, growth rates drop considerably. C. rhizophorae grow best during the rainy season due to a higher influx of nutrients into estuarine areas.

The size class between 4.1 and 6.0 cm is of most interest for fishers, as oysters of this size tend to yield the most meat. [4] The best time to harvest C. rhizophorae is 2 years after spawning.  

Fishing industry

C. rhizophorae is a vital fishery resource for the Caribbean and South Atlantic. [4] In the early 2000s, as many as 5,600 metric tons of C. rhizophorae were harvested in the Caribbean and South Atlantic. [7] Due to high consumer demands and declines in C. rhizophorae populations due to pollution, C. rhizophorae is now most commonly farmed using artificial reefs known as farming platforms. [7] These platforms are typically made of branches of mangrove trees suspended from racks in the inter- and sub-tidal regions. These allow for farmers to maintain populations of C. rhizophorae that meet consumer demands while preventing overfishing.

The artificial reefs of C. rhizophorae have also acted as nursery environments for many marine and estuarine species in the Caribbean. These artificial reefs also provide a reproductive substrate for fishes and protect them from predation. [8] [7]

Related Research Articles

<span class="mw-page-title-main">Oyster</span> Variety of families of Mollusc

Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not all oysters, are in the superfamily Ostreoidea.

<span class="mw-page-title-main">Eastern oyster</span> Species of bivalve

The eastern oyster —also called the Atlantic oyster, American oyster, or East Coast oyster—is a species of true oyster native to eastern North and South America. Other names in local or culinary use include the Wellfleet oyster, Virginia oyster, Malpeque oyster, Blue Pointoyster, Chesapeake Bay oyster, and Apalachicola oyster. C. virginica ranges from northern New Brunswick south through parts of the West Indies to Venezuela. It is farmed in all of the Maritime provinces of Canada and all Eastern Seaboard and Gulf states of the United States, as well as Puget Sound, Washington, where it is known as the Totten Inlet Virginica. It was introduced to the Hawaiian Islands in the 19th century and is common in Pearl Harbor.

<i>Crassostrea</i> Genus of bivalves

Crassostrea is a genus of true oysters containing some of the most important oysters used for food. Some species in the genus have been moved to the genus Magallana.

Broodstock, or broodfish, are a group of mature individuals used in aquaculture for breeding purposes. Broodstock can be a population of animals maintained in captivity as a source of replacement for, or enhancement of, seed and fry numbers. These are generally kept in ponds or tanks in which environmental conditions such as photoperiod, temperature and pH are controlled. Such populations often undergo conditioning to ensure maximum fry output. Broodstock can also be sourced from wild populations where they are harvested and held in maturation tanks before their seed is collected for grow-out to market size or the juveniles returned to the sea to supplement natural populations. This method, however, is subject to environmental conditions and can be unreliable seasonally, or annually. Broodstock management can improve seed quality and number through enhanced gonadal development and fecundity.

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<span class="mw-page-title-main">Fish hatchery</span> Aquaculture facility

A fish hatchery is a place for artificial breeding, hatching, and rearing through the early life stages of animals—finfish and shellfish in particular. Hatcheries produce larval and juvenile fish, shellfish, and crustaceans, primarily to support the aquaculture industry where they are transferred to on-growing systems, such as fish farms, to reach harvest size. Some species that are commonly raised in hatcheries include Pacific oysters, shrimp, Indian prawns, salmon, tilapia and scallops.

<span class="mw-page-title-main">Pacific oyster</span> Species of bivalve

The Pacific oyster, Japanese oyster, or Miyagi oyster, is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand.

<span class="mw-page-title-main">Oyster farming</span> Commercial growing of oysters

Oyster farming is an aquaculture practice in which oysters are bred and raised mainly for their pearls, shells and inner organ tissue, which is eaten. Oyster farming was practiced by the ancient Romans as early as the 1st century BC on the Italian peninsula and later in Britain for export to Rome. The French oyster industry has relied on aquacultured oysters since the late 18th century.

<span class="mw-page-title-main">Apalachicola Bay</span>

Apalachicola Bay is an estuary and lagoon located on the northwest coast of the U.S. state of Florida. The Apalachicola Bay system also includes St. George Sound, St. Vincent Sound and East Bay, covering an area of about 208 square miles (540 km2). Four islands, St. Vincent Island to the west, Cape St. George Island and St. George Island to the south, and Dog Island to the east, separate the system from the Gulf of Mexico. Water exchange occurs through Indian Pass, West Pass, East Pass and the Duer Channel. The lagoon has been designated as a National Estuarine Research Reserve and the Apalachicola River is the largest source of freshwater to the estuary. Combined with the Chattahoochee River, Flint River, and Ochlockonee River they drain a watershed of over 20,000 square miles (50,000 km2) at a rate of 19,599 cubic feet per second according to the United States Geological Survey in 2002.

<span class="mw-page-title-main">Spawn (biology)</span> Process of aquatic animals releasing sperm and eggs into water

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<i>Ostrea lurida</i> Species of bivalve

Ostrea lurida, common name the Olympia oyster, after Olympia, Washington in the Puget Sound area, is a species of edible oyster, a marine bivalve mollusk in the family Ostreidae. This species occurs on the northern Pacific coast of North America. Over the years the role of this edible species of oyster has been partly displaced by the cultivation of non-native edible oyster species.

<i>Crassostrea tulipa</i> Species of bivalve

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<span class="mw-page-title-main">Portuguese oyster</span> Species of bivalve

The Portuguese oyster is a species of oyster found in the southwest Iberian Peninsula, closely related to the Pacific oyster. Although first identified as a native European species, genetic studies have suggested the Portuguese oyster originated from the Pacific coast of Asia and was introduced to Europe by Portuguese trading ships in the 16th century. The species is usually found in coastal river mouths and estuaries.

<i>Ischadium</i> Genus of bivalves

Ischadium is a monotypic genus of mussels in the family Mytilidae. The sole species is Ischadium recurvum, known as the "Hooked mussel" or "Bent mussel". It can be found along the Atlantic coast of North America, ranging from Cape Cod to the West Indies. They are often found growing on Eastern oysters, either intertidal or subtidal. They also attach to other hard substrates, including artificial reefs and dead shells of brackish water clams, Rangia cuneata.

<i>Isognomon alatus</i> Species of bivalve

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<i>Amphibalanus amphitrite</i> Species of barnacle

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<i>Saccostrea cucullata</i> Species of bivalve

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<i>Ostrea equestris</i> Species of bivalve

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References

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  3. Cavaleiro, Nathalia P.; Solé-Cava, Antonio M.; Lazoski, Cristiano; Cunha, Haydée A. (2013-12-01). "Polymorphic microsatellite loci for two Atlantic oyster species: Crassostrea rhizophorae and C. gasar". Molecular Biology Reports. 40 (12): 7039–7043. doi:10.1007/s11033-013-2823-9. ISSN   1573-4978. PMID   24178344. S2CID   254836984.
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  6. 1 2 Dué, A; Costa, M; Silva Filho, E. A.; Guedes, E. A. C (2010). "Food items of Crassostrea rhizophorae (Guilding, 1828) (Bivalvia: Ostreidae) cultivated in a tropical estuary in Northeast Brazil". Bioikos. 24 (2): 83–93.
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