Observations of pigmented foci
and skin ulcers in silver porgy in the
St. Lucie Estuary

This webpage links to gross pathology observations from silver porgy (Diplodus argenteus) collected from St. Lucie Estuary Inlet, collection sites 10 and 30, March 24, 2011 (see interactive Google map for details). Silver porgy are part of this study because they are common inhabitants throughout the St. Lucie Estuary, have an ecology that is closely tied to the St. Lucie environment (generally benthic carnivores; feeds upon algae, mulloscs, crabs), and this species appears susceptable enviromental stress based on observations of external pigmented foci (colored spots) and ulceration.

Silver porgy were collected by hook and line from two locations in the St. Lucie River Inlet: Site 10 (South of Sailfish Point docks; West of Sailfish Point heliport) and Site 30 (South jetty of St. Lucie Inlet State Park); see interactive Google Map, below:

Phylum: Chordata
Subphylum: Vertebrata
Class: Actinopterygii (Ray-finned fishes)
Order: Perciformes (Perch-like fishes)
Family: Sparidae (Porgies)
Genus, species, subspecies: Diplodus argenteus caudimacula

 

 

The St. Lucie River is located in Southeast Florida and is fed from freshwater surface input as well as the Atlantic Ocean. This biologically diverse estuarine system is an essential component of the environmental and economic well-being of Martin, St. Lucie, and surrounding counties. The St. Lucie Estuary ecosystem is threatened by increasing residential and commercial development, industry and agriculture, and human negligence. Construction of extensive agricultural and urban drainage projects has substantially expanded the watershed of the St. Lucie Estuary. Effects of these man-made changes have caused significant alterations in the timing (excess wet season flows, insufficient dry season flows), distribution, quality, and volume of freshwater entering the estuary. Stressors such as these may have an impact on fish populations, and the health of individuals, including silver porgy.

External pigmented spots can be observerd in many fish species, either as part of their natural species-specific coloration, or in response to some sort of exposure or changing environmental condition. In our study, orange pigmented foci are not uncommon on silver porgy in the St. Lucie during certain seasonal collections. The image of the ventral surface of a silver porgy seen in the top banner of this webpage, shows a single orange focus bewteen the pelvic fins. The image to the right shows an ulcer of mild to moderate severity from the left side of a silver porgy. This ulcer is surrounded by orange pigment in the skin. Anecdotal evidence suggests that pigmented foci may be associated ulcer pathogenesis. This website links to gross- and histological images of pigmented foci and ulcers observed from silver porgy, in order to better understand the relationship between pigmented alterations, water quality and the pathogenesis of ulcerative lesions.

 

View case images showing pigmented foci:

[Case 11] [Case 12] [Case 13] [Case 14]

[Case 16] [Case 23] [Case 35]