Abstract

The red lionfish (Pterois volitans) is a popular marine aquarium species from the Scorpaenidae family, and is native to Indo-Pacific reef habitats. However, in the early 1990's they were introduced to waters off of Florida, and have since spread and thrived off of the southeastern U.S., Bermuda, Bahamas, and much of the Caribbean. Much research has been conducted to better understand the distribution, limitations, and impact of this invasive species.^1-5 However, in order to evaluate the physiological status of lionfish populations as they become established in their new range and monitor how their health status varies over time with changing ecological dynamics, basic health parameters need to be determined for this species. This study evaluates hematology, plasma biochemistry, and tissue enzyme activities of wild caught lionfish off the coast of North Carolina, USA. Findings will also be applicable to clinical evaluation of individual lionfish in aquarium settings.

Twenty-five lionfish with weight ranging from 223.9-1242.5 g were caught by hand net off the coast of North Carolina by research divers with the National Oceanic and Atmospheric Administration (NOAA). Fish were established in aquariums and sampled 3 days following capture. Each fish was anesthetized via bath administration of 125-ppm tricaine methanesulfonate (MS-222). Once immobilized, the fish were placed in dorsal or lateral recumbency, and blood was collected from the caudal tail vein using a heparinized 22-ga needle on a 3 ml syringe. Blood smears were prepared and hematocrit tubes centrifuged for in-house hematological analysis, and plasma was harvested from the remainder of the blood for biochemical analysis at a commercial laboratory (Antech Diagnostics). Blood smears were stained using Wright-Giemsa stain for estimated white blood cell and differential counts.

In addition, five lionfish (3 from NOAA and 2 from a display aquarium) were euthanized for health assessment of each population. Fish were euthanized by an overdose of MS-222, and full necropsies performed. Plasma was collected from each fish, along with 0.5 g samples of liver, kidney, muscle, and gastrointestinal tract, and 0.1 g samples of heart. Homogenates were prepared from each tissue, and the supernatants analyzed for alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyltransferase (GGT), lactate dehydrogenase (LD), and creatine kinase (CK).

Median (range) of values for selected analytes were as follows: PCV 34 (27-44) %, WBC 4.0 (2.0-8.2) x 10³/ml, TP 4.0 (2.9-6.3), AST 69 (24-236), ALT 1.0 (1.0-7.0), ALP 34.5 (16-66), CK 860 (198-4372), and glucose 26.5 (10-49). Neutrophils were the predominant white blood cell type, followed by lymphocytes.

Activity of ALP was high in liver and kidney, ALT was highest in heart and liver, AST was highest in heart and liver, LD had highest levels in heart and muscle, and CK was found in heart and muscle. Kidney was the only organ in which GGT activity was detected, but no measurable activities were detected in any plasma sample leaving it of questionable diagnostic value.

References

1.  Albins MA, Hixon MA 2008. Invasive Indo-pacific lionfish Pterois volitans reduce recruitment of Atlantic coral-reef fishes. Mar Ecol Prog Ser 367:233-238.

2.  Hammer RM, Freshwater DW, Whitfield PE 2007. Mitochondrial cytochrome b analysis reveals two invasive lionfish species with strong founder effects in the western Atlantic. J Fish Biol 71(Sup B):214-222.

3.  Kimbal ME, Miller JM, Whitfield PE, Hare JA 2004. Thermal tolerance and potential distribution of invasive lionfish (Pterois volitans/miles complex) on the east coast of the United States. Mar Ecol Prog Ser 283:269-278.

4.  Morris JA Jr, Akins JL, Barse A, Cerino D, Freshwater DW, Green SJ, Muñoz RC, Paris C, Whitfield PE 2008. Biology and ecology of the invasive lionfishes, Pterois miles and Pterois volitans. Proc Gulf Carib Fish Inst 61:1-6.

5.  Whitfield PE, Gardner T, Vives SP, Gilligan MR, Courtenay WR Jr., Ray GC, Hare JA. 2002. Mar Ecol Prog Ser 235:289-297.