Survival, growth ... of non-indigenous Nile tilapia

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Bojan Dolenc
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Survival, growth ... of non-indigenous Nile tilapia

Post by Bojan Dolenc » Tue Jun 14, 2011 5:19 am

Pamela J. Schofield, Mark S. Peterson, Michael R. Lowe, Nancy J. Brown-PetersonB & William T. Slack (2011): Survival, growth and reproduction of non-indigenous Nile tilapia, Oreochromis niloticus (Linnaeus 1758).I. Physiological capabilities in various temperatures and salinities. Marine and Freshwater Research, 2011, 62, 439–449.
http://www.publish.csiro.au/journals/mfr

Abstract

The physiological tolerances of non-native fishes is an integral component of assessing potential invasive risk. Salinity and temperature are environmental variables that limit the spread of many non-native fishes. We hypothesised that combinations of temperature and salinity will interact to affect survival, growth, and reproduction of Nile tilapia, Oreochromis niloticus, introduced into Mississippi, USA. Tilapia withstood acute transfer from fresh water up to a salinity of 20 and survived gradual transfer up to 60 at typical summertime (30°C) temperatures. However, cold temperature (14°C) reduced survival of fish in saline waters ≥10 and increased the incidence of disease in freshwater controls. Although fish were able to equilibrate to saline waters in warm temperatures, reproductive parameters were reduced at salinities ≥30. These integrated responses suggest that Nile tilapia can invade coastal areas beyond their point of introduction. However, successful invasion is subject to two caveats: (1) wintertime survival depends on finding thermal refugia, and (2) reproduction is hampered in regions where salinities are ≥30. These data are vital to predicting the invasion of non-native fishes into coastal watersheds. This is particularly important given the predicted changes in coastal landscapes due to global climate change and sea-level rise.
Additional keywords: dispersal, estuary, invasive species, osmoregulation, salinity.

Marine and Freshwater Research
62(5) 439-449 doi:10.1071/MF10207
Change in habit, producing change of function, is the main cause of the production of change in living structure. F. Wood Jones (1953) Trends of life

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Lisachromis
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Re: Survival, growth ... of non-indigenous Nile tilapia

Post by Lisachromis » Tue Jun 14, 2011 8:48 am

They've introduced Nile Tilapia into Mississippi? :shock:

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Bojan Dolenc
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Re: Survival, growth ... of non-indigenous Nile tilapia

Post by Bojan Dolenc » Tue Jun 14, 2011 9:40 am

Lisachromis wrote:They've introduced Nile Tilapia into Mississippi? :shock:
Nile tilapia is a relatively recent addition to the coastal Mississippi fauna, having escaped from an aquaculture facility in the late 1980s (Peterson et al. 2004, 2005; Schofield et al. 2007). It is the first cichlid fish known to become established in the region, which is one of the least studied areas of the USA in terms of non-indigenous species (Ruiz et al. 2000; Carlton 2001). Established populations in Mississippi have access to coastal marshes that lead directly to Mississippi Sound, where salinity rarely exceeds 20–28 in nearshore areas (Eleuterius 1976a, 1976b) and connect almost all estuaries in the State. Thus, there is concern that Nile tilapia could use estuarine regions as ‘salt bridges’ (sensu Brown et al. 2007) to spread along the Mississippi coastline and access new watersheds throughout the northern Gulf of Mexico. Once established, eradication of an invasive species is not always feasible (Lodge et al. 1998; Walther et al. 2009) and, therefore, it is important to not only understand how likely the fish are to survive various salinities when exposed to different seasonal temperatures, but also to document the effects of those environmental variables on the species’ ability to grow and reproduce.

In fact, tilapias appear to be the most widely distributed non-indigenous fishes worldwide, and have established in many of the tropical and subtropical environments to which they have gained access (Courtenay 1997; Costa-Pierce 2003). For example, Nile tilapia, Oreochromis niloticus, is one of the top 10 aquaculture species in the world (in terms of tonnage production) and has been introduced to at least 85 countries (third-most after common carp, Cyprinus carpio, and Mozambique tilapia, O. mossambicus). Although valued in aquaculture, once tilapia escape into native environments they have been linked to the decline of native species through several mechanisms, including egg predation, competition and habitat damage (e.g. increased eutrophication, vegetation destruction: reviewed by Canonico et al. 2005).
Change in habit, producing change of function, is the main cause of the production of change in living structure. F. Wood Jones (1953) Trends of life

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