Use of stable isotopes in benthic organic material as a baseline for estimating fish trophic positions in lakes

Estimating the trophic position of predators in food webs using stable isotopes requires establishing a “baseline”, typically served by bivalves or snails. However, the frequent absence of such organisms in lakes leaves researchers in a difficult situation. Here we test the hypothesis that trophic position (TP) of largemouth bass (LB; Micropterus salmoides) in lakes can be estimated from δ15N of benthic organic material (BOM) in littoral surficial sediment. δ15NLB as a function of δ15NBOM was significant across 51 lakes with an R2 of 0.84, supporting our hypothesis. In a subset of six lakes, the mean TPLB did not differ significantly when calculated using baselines of δ15N in BOM, unionid mussels (UN), gastropods (SN), or from a stable isotope mixing model. In a subset of 26 lakes, mean TPLB calculated from δ15NBOM and δ15NUN baselines were not significantly different, but TPLB calculated using δ15NBOM was not significantly correlated with TPLB calculated using δ15NUN. Although δ15NBOM should not be used interchangeably with δ15NUN as a baseline for estimating TPLB, δ15NBOM can be useful as a separate baseline where estimates of fish TP are needed in all study lakes given that mussels are frequently absent and BOM is always available for collection.

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Stable nitrogen isotopes as indicators of anthropogenic activities in small freshwater systems

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f01-038 ◽

2001 ◽

Vol 58 (5) ◽

pp. 870-878 ◽

Cited By ~ 95

Author(s):

James L Lake ◽

Richard A McKinney ◽

Frank A Osterman ◽

Richard J Pruell ◽

John Kiddon ◽

...

Keyword(s):

Largemouth Bass ◽

Trophic Position ◽

Anthropogenic Activities ◽

Inorganic Nitrogen ◽

Micropterus Salmoides ◽

Anthropogenic Activity ◽

Dissolved Inorganic Nitrogen ◽

Shoreline Development ◽

Freshwater Systems ◽

Nitrogen Concentrations

Stable nitrogen isotope ratios (δ15N) were measured in fish, mussel, and sediment samples taken from 17 small freshwater sites to examine food chain length and trophic position across sites affected by differing levels of anthropogenic activity. Both shoreline development and fish species composition varied greatly among sites, and a range of up to 11.2 was found for the δ15N values of largemouth bass (Micropterus salmoides). Fish δ15N values were baseline corrected using unionid mussel (Elliptio complanata) δ15N values. Predators, such as largemouth bass and chain pickerel (Esox niger), exhibited normalized δ15N values that were less variable than those of benthic-feeding fishes. Relationships between δ15N and dissolved inorganic nitrogen concentrations indicated that δ15N was a valid descriptor of eutrophication at sites with low dissolved inorganic nitrogen concentrations. The fraction of residential land in buffer zones surrounding sites was correlated with fish δ15N, indicating that urban development, and presumably human wastewater, resulted in elevated δ15N values in these small freshwater systems.

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Balancing Fisheries Management and Water Uses for Impounded River Systems

Balancing Fisheries Management and Water Uses for Impounded River Systems ◽

10.47886/9781934874066.ch26 ◽

2008 ◽

Keyword(s):

Largemouth Bass ◽

Micropterus Salmoides ◽

Adult Population ◽

Wild Fish ◽

Adult Size ◽

Catch Per Unit Effort ◽

Adult Age ◽

Mean Size ◽

The Mean

<em>Abstract</em>.—Despite the widespread use of supplemental stocking, survival of age-0 and age-1 stocked fish is often variable and stocking success is not commonly evaluated through adult size-classes. We evaluated the long-term contribution of stocked largemouth bass <em>Micropterus salmoides </em>from three annual stockings in 15 reservoirs in Illinois. Stocked largemouth bass were marked with fin clips and sampled for 5 years. Contribution of stocked fish to the population was highest for age-0 (21%) and age-1 largemouth bass (17%) but decreased significantly in adult fish (5%). Contribution of stocked bass was not associated with either populations of wild largemouth bass or latitude. Survival of stocked fish was similar to survival of wild fish through age 1. Age-0 abundance of wild and stocked largemouth bass were positively correlated in the fall following stocking, suggesting that similar factors may influence initial survival. Survival of stocked fish from age-1 to adult age decreased significantly compared to wild fish, resulting in low contribution of stocked bass to the adult population. Adult and age-1 catch per unit effort of stocked largemouth bass were positively correlated with the mean size of stocked bass in the first fall after stocking and the following spring, indicating that lakes with higher growth rates have increased contribution of stocked fish. We found limited contribution of stocked fish to adult largemouth bass populations due to low survival from age-1 to adult age. Assessments of fish stocking success should evaluate survival of stocked fish through adult ages or they may omit a critical period for mortality.

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