A B S T R A C TFor the future use of the marine benthic copepod Tisbe biminiensis in solid-phase sediment toxicological bioassays, the present study investigated the effect of muddy sediment from the Maracaípe estuary (northeastern Brazil), sediment particle size and the reference toxicant potassium dichromate on the species. Muddy sediment from Maracaípe can be used as control sediment, since it does not interfere in the copepod life-cycle and has metal contamination levels that are unlikely to produce any detrimental biological effects on benthic invertebrates. Neither survival nor fecundity was affected by grain size, suggesting that this species can be used with any kind of sediment from muddy to sandy. The sensitivity of T. biminiensis to K 2 Cr 2 O 7 in acute tests was similar to that of other organisms. The LC 50 (lethal concentration to 50% of the test organisms) medium values for T. biminiensis were 7.51, 4.68 and 3.19 mg L -1 for Cr in 48, 72 and 96 h, respectively. These results suggest that T. biminiensis is a promising organism for use in solid-phase sediment toxicity assessments. R E S U M OVisando o uso futuro do copépodo marinho bentônico Tisbe biminiensis em bioensaios toxicológicos de sedimentos na fase sólida, o presente estudo investigou o efeito do sedimento lamoso do estuário de Maracaípe (Nordeste do Brasil). Foram considerados a granolometria e o tóxico de referência dicromato de potássio sobre a espécie. O sedimento lamoso de Maracaípe pode ser usado como controle, uma vez que não interfere no ciclo de vida do copépodo e possui níveis de contaminação de metais que não causariam efeitos biológicos em invertebrados bentônicos. Nem a sobrevivência ou fecundidade foi afetada pelo tamanho do grão, sugerindo que esta espécie pode ser usada com qualquer tipo de sedimento, de lama a areia. A sensibilidade de T. biminiensis ao K 2 Cr 2 O 7 em testes agudos foi similar a de outros organismos. Os valores de CL 50 (concentração letal a 50% dos organismos) para T. biminiensis foram em média 7,51, 4,68 e 3,19 mg L -1 para o Cr em 48, 72 e 96h, respectivamente. Estes resultados sugerem que T. biminiensis é um organismo promissor para uso em avaliações de toxicidade com a fase sólida do sedimento.

The sister chromatid exchange test as an indicator of marine pollution: some factors affecting SCE frequencies in Mytilus galloprovincialis 'Dpto Bioloxia Fundamental, Xenetica, Universidade d e Vigo, E-36200 Vigo, Spain *~p t oBioloxia Celular e Molecular, Xenetica, Universidade da Corufia. E-15071 A Corufia, Spain ABSTRACT: The sister chromatid exchange (SCE) test is a widely used method to detect chemically induced genetic damage. This method has been applied in some aquatic species to monitor genetic pollutants in estuarine and marine environments. Dose response to 5-bromodeoxyuridine (BrdU) was investigated in the mussel Mytilus gallopror~incialis Lmk. Experimental assays were carried out by incorporating 4, 10, 20 and 40 pg ml-l BrdU in asynchronously growing mussel gill cell populations. SCE frequency was dose dependent both for mussel cells labelled with BrdU for a first round of replication followed by a second round without BrdU (24 + 3 6 h), and for mussel cells labelled with BrdU for 2 consecutive rounds of replication (60 h). For every dose assayed, s~gnificant differences in SCE frequencies were also found between these 2 kinds of BrdU treatments. The relationship between the duration of the BrdU treatment and the frequency of SCEs was also Investigated in M. galloprovincial~s.We tested the effect of in vivo BrdU incorporation for either the flrst cell cycle, or the first and second cell cycles in mussel gill cells. This paper shows that SCE frequencies remain constant for the different BrdU exposures (12+36, 12+48, 24+24, 2 4 + 3 6 and 36+24 h) assayed to obtain first cell cycle labell~ng, but a striking increase was noted in BrdU treatments (48, 60. 72, 84 and 96 h) for 2 consecutive cycles of labelling. A monthly study of SCE frequencies occurring in 2 natural populations from NW Spain was also performed during 1993. Significant differences in the frequency of SCE were detected both between populations and among months in the mussel populations. In most of the cases, noticeable interindividual variations in SCE frequencies were detected in mussels exposed to the same BrdU conditions.KEY WORDS: 5-Bromodeoxyuridine (BrdU) Biomonitoring -Mytilus galloprovincialis . Sister Chromatid Exchange (SCE)