Biochemical and Behavioural Alterations Induced by Arsenic and Temperature in Hediste diversicolor of Different Growth Stages

Abstract

Contamination with Arsenic, a toxic metalloid, is increasing in the marine environment. Additionally, global warming can alter metalloids toxicity. Polychaetes are key species in marine environments. By mobilizing sediments, they play vital roles in nutrient and element (including contaminants) cycles. Most studies with marine invertebrates focus on the effects of metalloids on either adults or larvae. Here, we bring information on the effects of temperature increase and arsenic contamination on the polychaete Hediste diversicolor in different growth stages and water temperatures. Feeding activity and biochemical responses-cholinesterase activity, indicators of cell damage, antioxidant and biotransformation enzymes and metabolic capacity-were evaluated. Temperature rise combined with As imposed alterations on feeding activity and biochemical endpoints at different growth stages. Small organisms have their antioxidant enzymes increased, avoiding lipid damage. However, larger organisms are the most affected class due to the inhibition of superoxide dismutase, which results in protein damage. Oxidative damage was observed on smaller and larger organisms exposed to As and temperature of 21 °C, demonstrating higher sensibility to the combination of temperature rise and As. The observed alterations may have ecological consequences, affecting the cycle of nutrients, sediment oxygenation and the food chain that depends on the bioturbation of this polychaete.

Keywords: behaviour; global warming; invertebrates; metalloids; oxidative stress.

Figure 1

Total Arsenic in Hediste diversicolor tissues from different class sizes after exposure to Arsenic at 16 °C (A) and at 21 °C (B). Different letters represent significant differences (p < 0.05) between conditions (lowercase letters for 16 °C; uppercase letters for 21 °C).

Figure 2

Feeding activity (time needed to detect and grab the food) 21 days after exposure to Arsenic and a temperature of 16 °C (A) and Arsenic and a temperature of 21 °C (B) of Hediste diversicolor from different class sizes. Different letters represent significant differences (p < 0.05) between conditions (lowercase letters for 16 °C; uppercase letters for 21 °C). Asterisk (*) represents significant differences (p < 0.05) among temperatures for the same class size.

Figure 3

Cholinesterase (ChE) activity measured in Hediste diversicolor from different class sizes after 28 days of exposure to Arsenic at a temperature of 16 °C (A) and 16 °C (B). Different letters represent significant differences (p ≤ 0.05) between conditions (lowercase letters for 16 °C; uppercase letters for 21 °C). Asterisk (*) represents significant differences (p < 0.05) among temperatures for the same class size.

Figure 4

Metabolism related parameters. (1) Electron transport system (ETS) at a temperature of 16 °C (A) and 21 °C (B) of Hediste diversicolor after 28 days of exposure to Arsenic. (2) Sugars content measured in H. diversicolor from different class sizes after 28 days of exposure to Arsenic at a temperature of 16 °C (A) and 21 °C (B). (3) Protein content 28 days after exposure to Arsenic and a temperature of 16 °C (A) and Arsenic and a temperature of 21 °C (B) of Hediste diversicolor from different class sizes. Different letters represent significant differences (p < 0.05) between conditions (lowercase letters for 16 °C; uppercase letters for 21 °C). Asterisk (*) represents significant differences (p < 0.05) among temperatures for the same class size.

Figure 5

Antioxidant enzymes: (1) Superoxide dismutase activity (SOD) measured in H. diversicolor from different class sizes after 28 days of exposure to Arsenic at 16 °C (A) and 21 °C (B). (2) Catalase (CAT) activity measured in H. diversicolor from different class sizes after 28 days of exposure to Arsenic at 16 °C (A) and 21 °C (B). Different letters represent significant differences (p < 0.05) between conditions (lowercase letters for 16 °C; uppercase letters for 21 °C). Asterisk (*) represents significant differences (p < 0.05) among temperatures for the same class size.

Figure 6

Glutathione-S-transferases (GSTs) activity measured in H. diversicolor from different class sizes after 28 days of exposure to Arsenic at 16 °C (A) and 21 °C (B) of Hediste diversicolor after 28 days of exposure. Different letters represent significant differences (p < 0.05) between conditions (lowercase letters for 16 °C; uppercase letters for 21 °C). Asterisk (*) represents significant differences (p < 0.05) among temperatures for the same class size.

Figure 7

Indicators of oxidative damage: (1) Lipid peroxidation (LPO) measured in Hediste diversicolor from different class sizes after 28 days of exposure to Arsenic and at 16 °C (A) and 21 °C (B). (2) Protein carbonylation (PC) measured in Hediste diversicolor from different class sizes after 28 days of exposure to Arsenic and 16 °C (A) and 21 °C (B). Different letters represent significant differences (p < 0.05) between conditions (lowercase letters for 16 °C; uppercase letters for 21 °C). Asterisk (*) represents significant differences (p < 0.05) among temperatures for the same class size.

Figure 8

Centroids ordination diagram (PCO) based on feeding activity and biochemical parameters, measured in Hediste diversicolor exposed to different As concentrations and sizes (0; 0.05; 0.25 mg/L and Small (S), Medium (M) and Large (L)) from both temperatures (16 °C and 21 °C). Pearson correlation vectors are superimposed as supplementary variables, namely feeding activity and biochemical data (r > 0.8).