Hyalella azteca

Hyalella azteca

Hyalella azteca
scud
Taxonomic classification
Class:	Malacostraca
Order:	Amphipoda
Family:	Dogielinotidae
Genus:	Hyalella
NCBI taxid:	294128
Resources
Information
Research interest:	ecotoxicology
Nomination:	i5K initiative
Date:	2011/08/19

i5K Arthropod Sequencing Initiative  Supported by: 1 (List of supporters)

Summary - Hyalella azteca is a freshwater epibenthic amphipod of interest to ecotoxicology and evolutionary biology. It is the primary invertebrate crustacean used in the U.S. for sediment toxicity testing and have been the subject of recent gene expression studies in ecotoxicogenomics. H. azteca is a species complex which has diverged in North America over the past 11 million years creating numerous ecotypes which are the subject of divergent evolutionary studies.

Introduction- Hyalella azteca is a freshwater epibenthic amphipod which lives near the sediment surface, burrowing in sediment and also scavenging on the leaf litter, algae, and detritus material on the sediment surface. They are primarily found on the sediment surface and in algal mats in nature and while their primary source of food varies by habitat, they appear to prefer epiphytic algae over detrital organic matter (Wang et al. 2004). However, under laboratory conditions, they may be found often burrowing in sediments (Ingersoll et al. 2000). They have a generation time of approximately 33 days (dependent on temperature) and reach a maximum length of about 7 mm in 120 days (Othman and Pascoe 2001).

H. azteca are tolerant of a wide range of habitats. The can survive temperature extremes of 0o C to 33o C; although optimal growth and reproduction occurs at 20-28o C. In addition, they are primarily found in freshwater habitats, but they are resistant to salinity, tolerating salinities up to15 o/oo (U.S. EPA 2000). They are also very amenable to different sediment types from silty to sandy sediments of various grain sizes (U.S. EPA 2000).

Toxicological Significance – Their nearly continuous contact with sediment, rapid generation time, and tolerance to varied environmental parameters has made H. azteca an ideal species for assessing sediment toxicity and the bioavailability of sediment contaminants. H. azteca is the primary amphipod crustacean used in the United Stated as an indicator of toxicity in freshwater contaminated sediment assessments and standard protocols for acute (10-day) and chronic (42-d) bioassays have been developed in the US and other countries for these organisms (Burton et al. 2003). H. azteca is a very sensitive indicator of toxicity in freshwater sediment toxicity tests, often showing increased sensitivity over other sediment-dwelling organisms. Sediment management decisions to protect aquatic life, such as site cleanup, and dredged material disposal are often influenced by sediment toxicity testing with H. azteca (U.S. EPA 2000). The organisms maintained by the US EPA for toxicity testing originated from a collection by A. Nebeker (ca. 1982) from a small stream near Corvallis, Oregon (Duan et al. 1997).

Evolutionary Significance – Hyalella azteca is a species complex, which due to its low morphological divergence was originally characterized as a single cosmopolitan species indigenous in lakes, streams and ponds from Latin America to Canada. The species H. azteca was first described from Mexico by Saussure in 1858 and was later redescribed from the original library collection by Gonzales and Watling in 2002 (Gonzalez and Watling 2002). Studies have revealed life history and morphological differences in H. azteca collected from different locations and habitats (e.g. Strong 1972, Wellborn 1994) , leading scientists to explore genetics of the H. azteca, which quickly delineated several different species (Duan et al. 1997, Thomas et al. 1997, Hogg et al. 1998, Witt and Herbert 2000, Duan et al. 2000). Evolution of different ecotypes of Hyalella has become of recent interest because isolated populations have become genetically distinct over the past 11 million years (Witt and Herbert 2000); however, convergent evolution appears to be occurring in similar habitats separated by large geographic distances (Wellborn et al. 2005). Understanding the differences in the sensitivity of genetically distinct populations of Hyalella to pollutants is also extremely relevant given their significance to environmental health and ecotoxicology (Hogg et al. 1998, Duan et al. 2000b).

References:

Burton, G. A., D. L. Denton, K. Ho, and D. S. Ireland. 2003. Sediment Toxicity Testing: Issues and Methods. Pages 111-150 in D. J. Hoffman, B. A. Rattner, G. A. Burton, and J. Cairns, editors. Handbook of Ecotoxicology. Lewis Publishers, Boca Raton, FL.

Duan, Y. H., S. I. Guttman, and J. T. Oris. 1997. Genetic differentiation among laboratory populations of Hyalella azteca: Implications for toxicology. Environmental Toxicology and Chemistry 16:691-695.

Duan, Y. H., S. I. Guttman, J. T. Oris, and A. J. Bailer. 2000a. Genetic structure and relationships among populations of Hyalella azteca and H-montezuma (Crustacea : Amphipoda). Journal of the North American Benthological Society 19:308-320.

Duan, Y. H., S. I. Guttman, J. T. Oris, and A. J. Bailer. 2000b. Genotype and toxicity relationships among Hyalella azteca: I. Acute exposure to metals or low pH. Environmental Toxicology and Chemistry 19:1414-1421.

U.S. EPA, 2000. Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates. Office of Research and Development, U.S. Environmental Protection Agency, Duluth, Minnesota.

Gonzalez, E. R. and L. Watling. 2002. Redescription of Hyalella azteca from its type locality, Vera Cruz, Mexico (Amphipoda : Hyalellidae). Journal of Crustacean Biology 22:173-183.

Hogg, I. D., C. Larose, Y. de Lafontaine, and K. G. Doe. 1998. Genetic evidence for a Hyalella species complex within the Great Lakes St Lawrence River drainage basin: implications for ecotoxicology and conservation biology. Canadian Journal of Zoology-Revue Canadienne De Zoologie 76:1134-1140.

Ingersoll, C. G., C. D. Ivey, E. L. Brunson, D. K. Hardesty, and N. E. Kemble. 2000. Evaluation of toxicity: whole-sediment versus overlying-water exposures with amphipod Hyalella azteca. Environ Toxicol Chem 19:2906-2910.

Othman, M. S. and D. Pascoe. 2001. Growth, development and reproduction of Hyalella azteca (Saussure, 1858) in laboratory culture. Crustaceana 74:171-181.

Strong, D. R. 1972. Life history variation among populations of an Amphipod (Hyalella azteca). Ecology 53:1103-1111.

Thomas, P. E., D. W. Blinn, and P. Keim. 1997. Genetic and behavioural divergence among desert spring amphipod populations. Freshwater Biology 38:137-143.

Wang, F., R. R. Goulet, and P. M. Chapman. 2004. Testing sediment biological effects with the freshwater amphipod Hyalella azteca: the gap between laboratory and nature. Chemosphere 57:1713-1724.

Wellborn, G. A. 1994. The Mechanistic Basis of Body-Size Differences between 2 Hyalella (Amphipoda) Species. Journal of Freshwater Ecology 9:159-168.

Wellborn, G. A., R. Cothran, and S. Bartholf. 2005. Life history and allozyme diversification in regional ecomorphs of the Hyalella azteca (Crustacea : Amphipoda) species complex. Biological Journal of the Linnean Society 84:161-175.