Abstract:

Cyprinodontiform fishes are dominant in marshes, but the patterns of habitat use can vary among species as well as life history stages. Therefore, when evaluating their potential as sentinel species, specifically responses to environmental stressors (e.g., oil spills), it is important to consider the temporal and spatial distribution of these highly localized fish within different marsh subhabitats (marsh edges, creeks, ponds, and depressions). Our recent work indicates the four most abundant cyprinodontiformes in Louisiana marshes are gulf killifish (Fundulus grandis), diamond killifish (Fundulus xenicus), sheepshead minnow (Cyprinodon variegatus), and sailfin molly (Poecilia latipinna). While the abundance of these fish in ponds and depressions is high, only a small portion (<1%) occur along the marsh edge. Fish in these subhabitats can be exposed to varying levels of temperature, salinity, and trace metal concentrations. These three factors control the uptake of trace elements into the otoliths of fish, an uptake that occurs in daily growth increments and provides a record of the fish’s chemical environment. Our objective was to determine if the otoliths of fish from different marsh subhabitats have distinguishing elemental signatures. The chemical compositions of 200 sagittal otoliths from the four fish species mentioned above were analyzed. Fish were collected across four subhabitats in marshes near Chauvin, Louisiana.

Suggested Citation:

Lopez-Duarte, Paola. 2016. Evaluating otolith microchemistry as a method to distinguish habitat-use patterns in marsh-resident fish. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7SQ8XBG

Purpose:

The ultimate goal of this study is to inform habitat-use patterns of marsh fish based on the chemical history of their otoliths.

Data Parameters and Units:

Sample ID: User defined sample identifier Subhabitat: Four marsh habitats from which fish were collected (pond, edge, creek, depression) Life history targeted in otolith: adult or juvenile Scientific name: Genus and species of fish from which otolith was collected Site: One of two locations (areas) where fish were collected (A or B) Elemental Isotopes (all expressed in mmol/mol and ratios to 48Ca): 24Mg, 31P, 34S, 55Mn, 57Fe, 63Cu, 66Zn, 85Rb, 88Sr, 118Sn, 138Ba, 208Pb, 238U. Site Information: Site A: 29.255658,-90.664247 Site B: 29.256922,-90.662714

Methods:

The levels of trace elements in recently-formed otolith rings were quantified using laser ablation with highly sensitive mass spectrometry. Fish samples collected in June-July 2012, otolith chemical analysis conducted August 2015. Species, sub-habitat, and sample size: Fundulus grandis (creek n=20, depression n=19, edge n=10, pond n=19), Fundulus xenicus (creek n=18, depression n=20, edge n=1, pond n=20), Poecilia latipinna (creek n=10, depression n=11, edge n=4, pond n=22), Cyprinodon variegatus (depression n=4, pond n=20)

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