Initial recolonization of benthic fauna in defaunated sediment contaminated with octylphenol: Field microcosm exposure study

Abstract

Recolonization of benthic fauna in defaunated sediment contaminated with octylphenol (OP) has been investigated by the use of in situ microcosm exposure study. Trays with defaunated sediment (control) and those treated with five OP concentrations (0.59, 5.4, 7.6, 66, and 660 μg g 1 , sediment dry weight (DW)) were exposed at the subtidal (ca. 10 m), in the southern coast of Korea, over two months. The initial response (after one-month exposure) of macrozoobenthos at the trays of control and three lower OP (0.59-7.6 μg g 1 DW) showed rapid colonization of macrozoobenthos with high diversity and abundance. However, the species number sharply decreased after two-month exposure, particularly at the tray of greatest OP (660 μg g 1 DW) treated with species number from 15 (after 30-days) to 3 (after 70-days). Other univariate indices such as abundance and biomass of benthic macrofauna also showed concentration-and time-dependent declines, indicating a potential adverse effect of OP on benthic community recolonization. Further, the multi-dimensional scaling (MDS) analysis that clearly separated two distinct faunal groups of macrobenthos during exposure supported the concentration-dependant recolonization followed by succession at the OP concentration of ¤7.6 μg g 1 DW. Similar to macrofauna, the meiofaunal abundance significantly decreased at the OP concentration of ¤7.6 μg g 1 DW, indicating certain threshold of OP between 7.6-66 μg g 1 DW that caused adverse effect on benthic community recolonization. Although the critical adverse OP concentration found in community level was relatively high compared to the environmental concentrations (ppb levels) reported in coastal sediments, it should be pointed out that certain species could be influenced by the exposure of lower OP concentrations.

Macrofaunal recolonization of copper-contaminated sediments in San Diego Bay

“…Sediment used in the experiment was collected from the high-Cu and low-C study sites by multiple deployments of a small custom-made gravity corer containing a removable Plexiglas tube (surface area = 20.4 cm -2 ). Sediment from each site (mouth and head) was defaunated by successive freezing and thawing at -20˚C (Santos and Simon 1980;Bolam et al 2004;Stocum and Plante 2006;Ryu et al 2010). Sediment was further wet-sieved (500 µm) to remove large particles, shell remains and dead fauna.…”

“…Freezing (and sieving) of sediment prior to deployment has been used extensively in field experiments examining the effects on recolonization or community structure of a broad range of pollutants such as metals (e.g. Austen et al 1994;Olsgard 1999;Trannum et al 2004), octylphenol (Ryu et al 2010), crude oil (Berge et al 1987;Berge 1990); and tributyltin (Austen and McEvoy 1997) without apparent alteration of bioavailability. The tray design (Appendix A Fig.…”