environmental benefits
Oysters are both keystone species and ecological engineers, meaning they greatly impact their surrounding ecosystem. Growing efforts via farms and restoration initiatives both positively enhance their localized waterways by:
- Filtration - Oysters feed on phytoplankton by filtering water; this removes particles from the water, resulting in increased water clarity. This allows underwater vegetation to receive more sunlight and nurture their growth.
- Nutrient removal - Excess nitrogen and phosphorus are nutrients that can cause harmful algal blooms. By water filtration, oysters sequester nitrogen and phosphorus into their shells and tissue. If oysters are harvested from the water, these nutrients are removed permanently. If oysters stay in water, they've still minimized the accumulation of these nutrients in the water column.
- Shoreline protection - Oyster reefs stabilize underwater sediment, minimizing erosion and damage from storm events.
- Creating habitat - Accumulation of oysters creates a habitat supporting a diverse ecosystem. A developed reef provides shelter for invertebrates and small fish while giving larger fish a place to dwell and feed. Oyster reefs also provide a setting place for new oyster larvae to attach to in the wild.
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Spat-on-shell: Oyster larvae are set onto and grow on a discarded, adult-sized oyster shell. Several spat may grow on one shell eventually forming a cluster of oysters. Spat-on-shell is typically used in restoration due to their reef building capabilities. Single seed: Oyster larvae are set onto a small piece of material. When the spat grows large, the oyster shakes off this piece and is a stand-alone oyster! Single seed oysters are typically grown for the consumption market. |
Spat-on-Shell Oysters
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Single Seed Oysters
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consumption vs. restoration
Consumption: These oysters are grown by farmers for market/human consumption. Typically, single seed oysters, also called "cultchless" (see above), are grown for the consumption market and are sold at a "market size" of 2-3 inches. Oysters are high in nutritional value, having high protein content, vitamin D, zinc, iron and copper.
Restoration: These oysters are grown with the end-goal of outplanting them to a reef site to re-establish their population. Typically, spat-on-shell oysters (see above) are used because of their larger, reef-building structure.
Restoration: These oysters are grown with the end-goal of outplanting them to a reef site to re-establish their population. Typically, spat-on-shell oysters (see above) are used because of their larger, reef-building structure.
life cycle
Wallace, R.K., P. Waters, and F.S. Rikard. 2008. Oyster hatchery techniques. SRAC (Southern Regional Aquaculture Center), Publication 4302.
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Male and female oysters can reproduce in the wild and in hatcheries where natural conditions are mimicked. When ready to spawn, oysters release their respective gametes into the water column where eggs are fertilized. The fertilized eggs hatch into free-swimming larvae that develop via three separate life stages (trochophore, veliger, and pediveliger) over the next few weeks. The non-feeding trochophore stage transitions into the feeding veliger stage. After the thin-shelled veliger develops a "foot" and eye spots, it is considered a pediveliger. Pediveligers are responsible for finding suitable substrate (cultch) to attach itself for life and metamorphose spat, a small version of the classic oyster. From here, the oyster feeds and grows into adulthood.
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