Effects of salinity on growth and ion regulation of juvenile alligator gar Atractosteus spatula

Schwarz, Daniel; Allen, Peter J.

doi:10.1016/j.cbpa.2013.12.012

Cited by 22 publications

(23 citation statements)

References 40 publications

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“…Trials conducted at 50-d posthatch resulted in greater than 90% survival to 18‰ salinity, and 100% survival of advanced age-0 fish (330 d old) was reported at 24‰ (Suchy 2009;Schwarz and Allen 2014). Salinity tolerance often increases with size and age (Parry 1960;Conte and Wagner 1965;Stickney 1991;Altinok et al 1998;Schwarz and Allen 2014), which is consistent with our observation that few fish exhibited a bay signature near the core, yet many fish used salt water later in life. Bay habitats are extensive, supporting more than 500,000 ha of coastal wetland and 100,000 ha of submerged aquatic vegetation in Texas (Table 1; USEPA 1999).…”

supporting

confidence: 86%

Population Structure of Alligator Gar in a Gulf Coast River: Insights from Otolith Microchemistry and Genetic Analyses

Daugherty

Pangle

Karel

et al. 2017

N American J Fish Manag

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Growing interest in the Alligator Gar Atractosteus spatula among anglers and fishery managers has inspired efforts to better manage populations. Successful management requires identifying population structure and understanding the distribution of stocks and associated differences in life history. This is particularly important in river systems along the coast of the Gulf of Mexico, where transitions from freshwater rivers to saltwater bays provide the potential for life history diversification. We used otolith microchemistry and genetics to assess population structure of Alligator Gars in the Guadalupe River–San Antonio Bay system, Texas. Lifetime Sr:Ca revealed three, distinct life histories that differed in prevalence across the system. River‐resident fish (i.e., fish exclusive to freshwater) were present throughout the river but were most common in the uppermost river reach (74% of upper river fish). Transient fish that used both river and bay habitats were also found throughout the river but were most prevalent in the lowermost river reach (66% of lower river fish) and bay (91% of bay fish). Bay residents (i.e., fish exclusive to salt water) were detected but comprised only 9% of bay fish. Haplotype diversity based on mitochondrial DNA was lowest in the upper river, indicating limited gene flow compared with the lower river and bay. Similarly, nuclear DNA analyses indicated nonrandom mating between fish from the upper river, lower river, and bay. The differences in Alligator Gar movement and genetics along the river–bay continuum suggest the presence of a river resident stock that predominates the upper river, and a transient stock that predominates the lower river and bay. Therefore, a local‐scale management approach, consistent with the spatial partitioning between stocks, would conserve life history and genetic diversity within the system and provide opportunities to meet the needs of a diverse angling constituency. Understanding how population dynamics differ between stocks is needed to develop appropriate fishery management objectives and corresponding regulations for Alligator Gar. Received May 20, 2016; accepted December 2, 2016 Published online February 27, 2017

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supporting

confidence: 86%

Population Structure of Alligator Gar in a Gulf Coast River: Insights from Otolith Microchemistry and Genetic Analyses

Daugherty

Pangle

Karel

et al. 2017

N American J Fish Manag

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“…DYB allocated energy for osmoregulation at the expense of growth. This is consistent with the observations of Schwarz and Allen [29], who demonstrated that growth rate diminished in juvenile alligator gar (Atractosteus spatula) at hyperosmotic salinities whereas Na + /K + -ATPase activity increased with increasing environmental salinity. Evidences of such tradeoffs have been also reported for the rotifer Brachionus plicatilis in which exposure to gradually increasing salinity resulted in negative correlations between Na + /K + -ATPase activity and both growth rate and egg production [30].…”

Section: Discussionsupporting

confidence: 93%

Salinity fluctuation influencing biological adaptation: growth dynamics and Na⁺/K⁺-ATPase activity in a euryhaline bacterium

Yang

Song

et al. 2017

J Basic Microbiol

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Although salinity fluctuation is a prominent characteristic of many coastal ecosystems, its effects on biological adaptation have not yet been fully recognized. To test the salinity fluctuations on biological adaptation, population growth dynamics and Na /K -ATPase activity were investigated in the euryhaline bacterium Idiomarina sp. DYB, which was acclimated at different salinity exposure levels, exposure times, and shifts in direction of salinity. Results showed: (1) bacterial population growth dynamics and Na /K -ATPase activity changed significantly in response to salinity fluctuation; (2) patterns of variation in bacterial growth dynamics were related to exposure times, levels of salinity, and shifts in direction of salinity change; (3) significant tradeoffs were detected between growth rate (r) and carrying capacity (K) on the one hand, and Na /K -ATPase activity on the other; and (4) beneficial acclimation was confirmed in Idiomarina sp. DYB. In brief, this study demonstrated that salinity fluctuation can change the population growth dynamics, Na /K -ATPase activity, and tradeoffs between r, K, and Na /K -ATPase activity, thus facilitating bacterial adaption in a changing environment. These findings provide constructive information for determining biological response patterns to environmental change.

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“…Additional trials 50 d posthatch resulted in over 90% survival to 18‰. Schwarz and Allen () reported 100% survival of advanced age‐0 fish (<400 mm TL) at 24‰. Increases in salinity tolerance with size and age have been reported for other fishes (Parry ; Conte and Wagner ; Stickney ; Altinok et al.…”

Section: Discussionmentioning

confidence: 88%

Alligator Gars in Texas Coastal Bays: Long‐Term Trends and Environmental Influences

2018

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Recognition of the recreational and conservation value of the Alligator Gar Atractosteus spatula has spurred efforts to understand its biology, ecology, and status in river–reservoir systems throughout their range. However, Alligator Gars have also been found in the coastal bays that link these rivers to the Gulf of Mexico. Little is known about the species in saltwater environments or their potential role in coastal fish communities. For that reason, we analyzed 37 years (1975–2012) of standardized gill‐net catches of Alligator Gars in 10 Texas bays to characterize spatiotemporal trends in abundance and size structure and identify influential environmental covariates. Over 28,000 Alligator Gars (113–2,040 mm TL) were collected during 24,756 net‐nights of effort. The species was generally omnipresent both spatially and temporally; however, catch per unit effort varied by two orders of magnitude and was both cyclical and synchronous among bays. Trends in catch and size structure were consistent in most bays, which is indicative of stable abundance and dynamic rates. Current salinity and freshwater inflows, as well as catch rates, salinity, and freshwater inflows during the previous sampling year, explained significant proportions of the variation in catch in all but one system. Generally, periods of increased catch were associated with lower salinity and higher freshwater inflow, though Alligator Gars continued to be collected at salinities over 35‰. Analyses revealed that Alligator Gar catches in Texas bays were similar to or considerably greater than those of Bull Sharks Carcharhinus leucas, which are considered the most abundant top predator in these systems. The broad distribution of the Alligator Gars along the coast, coupled with its high relative abundance, highlight the need to understand the species’ role in coastal food webs and ecosystem function, with the ultimate goal of improving our ability to manage both Alligator Gar populations and coastal communities.

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Effects of salinity on growth and ion regulation of juvenile alligator gar Atractosteus spatula

Cited by 22 publications

References 40 publications

Population Structure of Alligator Gar in a Gulf Coast River: Insights from Otolith Microchemistry and Genetic Analyses

Population Structure of Alligator Gar in a Gulf Coast River: Insights from Otolith Microchemistry and Genetic Analyses

Salinity fluctuation influencing biological adaptation: growth dynamics and Na⁺/K⁺-ATPase activity in a euryhaline bacterium

Alligator Gars in Texas Coastal Bays: Long‐Term Trends and Environmental Influences

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Effects of salinity on growth and ion regulation of juvenile alligator gar Atractosteus spatula

Cited by 22 publications

References 40 publications

Population Structure of Alligator Gar in a Gulf Coast River: Insights from Otolith Microchemistry and Genetic Analyses

Population Structure of Alligator Gar in a Gulf Coast River: Insights from Otolith Microchemistry and Genetic Analyses

Salinity fluctuation influencing biological adaptation: growth dynamics and Na+/K+-ATPase activity in a euryhaline bacterium

Alligator Gars in Texas Coastal Bays: Long‐Term Trends and Environmental Influences

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Salinity fluctuation influencing biological adaptation: growth dynamics and Na⁺/K⁺-ATPase activity in a euryhaline bacterium