Ecology: Pectinatella magnifica are typically found in lentic environments including freshwater lakes, ponds, and swamps, but can also be found in lotic environments (i.e., streams). The colonies are sessile with little preference among attaching surfaces (Joo et al. 1992), frequently found attached to rocks, wood, aquatic vegetation, pilings, or other submerged surfaces. On rare occasions the colonies will be found free-floating (Ricciardi and Reiswig 1994, Wood 2010, Joo et al. 1992). Pectinatella magnifica has been defined as a warm water species (Ricciardi and Reiswig 1994) although the species can display a wide temperature tolerance (4-32 °C) (Everitt 1975, Ricciardi and Reiswig 1994), but cannot tolerate saline waters (Everitt 1975).
Pectinatella magnifica can reproduce in several ways. Zooids can “clone” themselves by budding, but they can also create eggs and sperm and reproduce sexually. Pectinatella magnifica, like other freshwater bryozoans, can also form hard, round “statoblasts” which function like seeds. The creation of statoblasts is unique to bryozoans allowing them to endure variable and uncertain conditions of freshwater environments (Ricciardi and Reiswig 1994), although the statoblasts do not tolerate freezing temperatures (Wood pers. comm. 1997). Each statoblast can create a new colony (Ricciardi and Reiswig 1994). Pectinatella magnifica are known to have oscillating, annual population sizes in a waterbody. The current overwintering theory from Wood (pers. comm. 1997) is that statoblasts are created in the fall, which can disperse widely as the bryozoans decompose. The statoblasts attach to free clumps of algae or debris which then sinks to the bottom of the waterbody. The following spring, as that material decays, the statoblasts are released to float back to the surface and germinate. The summer germination produces quantities of "larvae," or little colonies that look like miniature blimps. The larvae are free-swimming for 2-24 hours and then settle on a suitable substrate and establish new colonies for a late summer statoblast-producing generation.
The individual P. magnifica zooids have mucous-coated tentacles that trap diatoms, phytoplankton, and other microscopic organisms, where cilia, or tiny hairs lining the tentacles, sweep the food to the mouth (Ricciardi and Reiswig 1994, Wood 2010). Individual zooids may filter an average of 8.8 ml of water/ day (Bullivant 1968).
Impact of Introduction: Pectinatella magnifica can become so abundant during warm months they have the potential to clog fishing nets, foul power plant water systems, and obstruct municipal water systems and other types of water pipes (Ricciardi and Reiswig 1994, Wood 2010).
Pectinatella magnifica can increase water clarity by removing large quantities of suspended material from the water including diatoms, suspended algae, and inorganic clay/silt. Over time, the clearer waters may promote algal and macrophytic growth that can restructure the ecosystem (Wood pers. comm. 1997).
Pectinatella magnifica can serve as an intermediate host of Tetracapsuloides bryosalmonae, a myxozoan parasite that causes Proliferative Kidney Disease (PKD) in salmonids (Okamura and Wood 2002). PKD is especially problematic for rainbow trout (Oncorhynchus mykiss) aquaculture in the western U.S. (Merck 2015).
References: (click for full references)
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Everitt, B. 1975. Fresh-water Ectoprocta: distribution and ecology of five species in southeastern Louisiana. Transactions of the American Microscopical Society:130-134.
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This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.