Clinical Copper Toxicosis in a Large Mixed Group of Marine Invertebrates

Abstract

A mixed group of 441 marine invertebrates was collected in Southern California. After a large mortality event, numerous water quality parameters were evaluated. Copper was present at 33 μg/L, which is below the documented toxic level. No other toxins were identified. To investigate whether copper was the etiology for the mass mortality, purple sea urchins, Strongylocentrotus purpuratus , were used as sentinel species, as they were the most severely affected during the mortality event. Purple sea urchins were placed in multiple test systems of varying copper concentrations and died in periods of time proportionate to copper concentrations. Clinical signs, disease progression, and pathologic lesions were similar between test systems and the original mortality event. Copper caused disease and death in purple sea urchins at concentrations from 15 to 50 μg/L. The source of the copper toxicity was identified as sand filters contaminated by brass pump components.

Lesions of Copper Toxicosis in Captive Marine Invertebrates With Comparisons to Normal Histology

“…42 The clinical investigation and diagnostic methods used to determine that copper was the etiologic agent are available. 42 Six animals were euthanized with 30% magnesium sulfate (Safeway Inc, Pleasanton, CA) and submitted for histologic examination.…”

“…Group 1 was submitted in 10% neutral buffered formalin by an aquarium in Southern California that had a mass mortality event due to copper toxicosis; 333 of 441 wild-caught marine invertebrates died due to a water copper concentration of 33 ppb. 42 The clinical investigation and diagnostic methods used to determine that copper was the etiologic agent are available. 42 Six animals were euthanized with 30% magnesium sulfate (Safeway Inc, Pleasanton, CA) and submitted for histologic examination.…”

“…42 The clinical investigation and diagnostic methods used to determine that copper was the etiologic agent are available. 42 Six animals were euthanized with 30% magnesium sulfate (Safeway Inc, Pleasanton, CA) and submitted for histologic examination. Following fixation in 10% neutral buffered formalin, entire specimens or calcified tissues from purple sea urchins and sea stars were decalcified using 0.5 M ethylenediamine tetra-acetic acid, pH 8.0 (Fisher Scientific, Pittsburg, PA) for 24 to 72 hours prior to trimming.…”

“…Group 2 was submitted in formalin by the same aquarium and consisted of 4 purple sea urchins that were experimentally exposed to 40-ppb copper in the water. 42 For this experiment, 4 newly caught purple sea urchins from the same wild population as group 1 were placed in a test tank with 2-ppb copper for 1 week. 42 At the end of 1 week, copper was added to the test system until the water concentration equilibrated to 40 ppb.…”

“…Three groups were examined histologically: Group 1: 6 animals with spontaneous copper toxicosis-a California sea hare, purple sea urchin, sunburst anemone, knobby star, bat star, and brittle star Group 2: 4 purple sea urchins with experimentally induced copper toxicosis Group 3: 6 wild-caught animals representing all aforementioned species, used as histologic controls Group 1 was submitted in 10% neutral buffered formalin by an aquarium in Southern California that had a mass mortality event due to copper toxicosis; 333 of 441 wild-caught marine invertebrates died due to a water copper concentration of 33 ppb. 42 The clinical investigation and diagnostic methods used to determine that copper was the etiologic agent are available. 42 Six animals were euthanized with 30% magnesium sulfate (Safeway Inc, Pleasanton, CA) and submitted for histologic examination.…”