PARENT SESSION
70 - Metal Pollution: From Exposure to Ecological Effects
8:00 AM to 6:30 PM, Wednesday, 15 May 2002
Exhibition Area

(70-85) Lethal and sublethal effects of cadmium on Crangon crangon from contrasting environments .

Culshaw, Caroline^*,1, Newton, Lyn¹, Bird, David¹, ¹ University of the West of England, Bristol, UK.

ABSTRACT- Heavy metals such as cadmium (Cd) are persistent pollutants, which accumulate in and can be toxic to marine organisms. The Severn Estuary, UK, has a history of metal contamination and high bioavailability of Cd. The brown shrimp, Crangon crangon is a benthic, coastal species and is vulnerable to metal contamination. C. crangon are abundant in the Severn Estuary but studies have suggested that shrimp size has decreased since the 1940s which could be due to anthropogenic activity. In this study, the effects of Cd on a key species in coastal ecosystems have been investigated. C. crangon from the Severn Estuary contain significantly higher levels of Cd (15.4±7.9g g^-1 dwt) than C. crangon from an uncontaminated site, the Exe Estuary, UK (1.2±0.3g g^-1 dwt). Storage of Cd requires a method of detoxification such as production of the metal binding protein, metallothionein (MT). MT levels in Severn Estuary shrimp (336±38g g^-1) are significantly higher than in shrimp from the Exe Estuary (227±37g g^-1). Studies of acute toxicity of Cd to C. crangon using 96h LC50 tests suggests that Severn Estuary shrimp (1.72±0.58mg l^-1) may be more tolerant to Cd than Exe Estuary shrimp (1.16±0.64mg l^-1) and this could be attributed to enhanced MT production. Sub-lethal effects of Cd were investigated to examine environmentally relevant implications at the population level. Cd is thought to affect locomotor activity in Severn Estuary C. crangon; exposure to waterborne Cd for 3 weeks significantly reduced tendency to bury. Disruption of normal behaviour patterns such as burying to avoid predators and the ability to catch prey could impact on populations and will be discussed.

Key words: Crangon crangon, cadmium, metallothionein, sub-lethal effects