The chronic effects of oil pollution on marine phytoplankton in a subtropical bay, China

Abstract

To evaluate the effects of crude oil water accommodated fraction (WAF) on marine phytoplankton community, natural phytoplankton collected seasonally from the Yueqing bay were exposed to eight groups of crude oil WAF for 15 days under laboratory conditions. Chlorophyll a and cell density were measured, and species of phytoplankton were identified every 24 h to reflect the change of phytoplankton community. The results showed that (1) High concentrations (≥ 2.28 mg l(-1)) of oil pollution would greatly restrain phytoplankton growth (p<0.001), decrease chlorophyll a content and cell density, whereas low concentrations (≤ 1.21 mg l(-1)) did not restrain its growth but rather promoted the phytoplankton growth. (2) The biodiversity, evenness, and species number of phytoplankton were all significantly influenced by crude oil WAF in all seasons (p<0.001). (3) The dominant species changes were different under different pollutant concentrations in different seasons. Different species had different tolerances to the oil pollution, thus leading to abnormal succession.

Effects of Macondo Oil on Phytoplankton from Grand Isle, Louisiana

“…The mechanisms by which low concentrations of oil enhance phytoplankton growth are unclear, but enhancements of growth or photosynthetic rates similar to the effects we observed (Figure 1) have been reported in several other studies [13,15,19,23,29,31,57]. The positive effects may be indirect and involve interactions with into lipids or other components of the cell in sufficient concentrations to upset normal metabolic functions.…”

“…The extent of inhibitory effects depends very much on the composition of the oil. Analogous studies have examined the effects on natural phytoplankton communities of crude oil [28][29][30][31][32][33][34], pyrene [35], and fuel oil [23,29,36,37]. The results of those studies have been generally consistent with the studies on individual species.…”

“…A number of previous investigators have reported stimulatory effects of oil on phytoplankton growth or photosynthesis at low oil concentrations, typically less than 1 mg L -1 , and inhibition at high oil concentrations [13,15,19,23,[29][30][31]. The toxicity of crude oil to phytoplankton results from a variety of effects that reflect the complex composition of crude oil.…”

“…Several studies, for example, have indicated that diatoms are more tolerant to oil than other classes of phytoplankton [28,30,34,59], although diatoms are sometimes outcompeted by other classes of phytoplankton in the presence of oil [60,61]. The impact of oil on diatoms varies between species and as a function of cell size [15,30,31,34,62]. The mechanisms that underlie the cell size effects are unclear and may involve surfaceto-volume considerations [33,63] as well as changes in predation pressure [30].…”

“…The results of those studies have been generally consistent with the studies on individual species. Low concentrations of oil apparently have a positive effect on at least some components of natural phytoplankton communities [29][30][31]37], whereas high concentrations are invariably inhibitory. Remarkably, Varela et al [36] detected few if any adverse effects of the Prestige oil spill on plankton communities off the northwestern coast of Spain, although the sunken tanker released an estimated 63,000 tons of fuel oil and polluted thousands of kilometers of coastline.…”