Mercury concentrations in south Texas game fishes

Authors

E. Anthony Reisinger, University of Texas at Brownsville

Date of Award

3-2006

Document Type

Thesis

Degree Name

Master of Science in Interdisciplinary Studies (MSIS)

Department

Biology

First Advisor

Dr. Genaro Lopez

Second Advisor

Dr. Gene J. Paull

Third Advisor

Dr. Nancy Schlight

Abstract

Mercury (Hg) is one of the most ubiquitous and controversial metals in the world primarily due to the toxicity of the organic form of the metal, methylmercury (MeHg). MeHg is a neurotoxin at high levels, known to manifest its effects on humans primarily through consumption of certain fish and marine mammals, which tend to bioaccumulate MeHg in their tissues over time. Increased fish consumption and, thus, mercury intake in residents of coastal areas necessitates a better awareness of MeHg content in game fish species, thus the subject of this study.

Three hundred thirty-nine tissue samples were taken from 19 south Texas marine species collected primarily at three fishing tournaments in 2004, tested for total Hg concentrations and analyzed with regression analyses and ANOVA. Results of individual species regression analyses all indicate exponential correlations for the comparisons of fish length (curved fork length for pelagic species and total length for the remainder) vs. total Hg. Sampled species were divided into four groups for further analysis: demersal vs. pelagic and inshore vs. offshore. Inshore and demersal fish species were found to exhibit mean concentrations of total Hg of 0.22 and 0.19 ppm. Both offshore and pelagic fish species had higher mean total Hg concentrations of 0.80 ppm. Two species were found to equal or exceed the U.S. Food and Drug Administration's action level of 1.0 ppm for fish. Those were blackfin tuna (Thunnus atlanticus) and king mackerel (Scomberomorus cavalla). Tissue samples were analyzed from blue crab (Callinectes sapidus) taken from the Arroyo Colorado, yielding a low unadjusted mean total Hg concentration of 0.15±0.08 ppm for a mean carapace length 14. 5 cm. Consumption limit comparisons are presented for 11 south Texas game fish species using EPA recommendations based on a reference dose (RID) of 0.0001 mg/kg of body weight/day (U.S. EPA, 1999). Similar comparisons are offered for different size ranges of nine of those species with significant length to total Hg relationships.

Comments

Copyright 2006 E. Anthony Reisinger Jr. All Rights Reserved.

Granting Institution

University of Texas at Brownsville