Toxicity estimates for diuron and atrazine for the tropical marine cnidarian Exaiptasia pallida and in-hospite Symbiodinium spp. using PAM chlorophyll-a fluorometry.

Effective ecotoxicological risk assessments for herbicides in tropical marine environments are restricted by a lack of toxicity data, sensitive test methods and endpoints for relevant species, and this requires rectification. The symbiotic sea anemone Exaiptasia pallida is a suitable test species, representing the phylum Cnidaria and allowing for assessments of toxicological responses of both the animal host and in-hospite Symbiodinium spp. Pulse amplitude modulated (PAM) chlorophyll-a fluorometry is recognised as a valuable ecotoxicological tool, and here newly-developed test methods are presented using PAM fluorometry to measure herbicide effects on photosynthetic efficiency of in-hospite Symbiodinium spp. Additionally, measurements on healthy laboratory-reared E. pallida provide baseline data demonstrating the normal effective quantum yield (EQY) and the maximum electron transport rate (ETRm) for Symbiodinium spp. in the absence of herbicide stress. Concentration-dependant reductions in the EQY and ETRm occurred during diuron and atrazine exposures; a mean 48-h EC50 (effective concentration; 50%) of 8µg/L of diuron was estimated, however atrazine elicited a much lower toxicity. Twelve-day exposures to 10-200µg/L diuron showed that the greatest EQY effect occurred during the first 48h, with little subsequent change. However, longer exposures to the lowest diuron treatment (1µg/L) showed the lowest EQYs after 96h followed by recovery to control levels within 12d. Furthermore, asexual reproduction was inhibited during 12-d exposures to diuron, and 12-d EC50 values of 100 and 132µg/L were estimated to inhibit successful reproduction of pedal lacerates and juveniles by 50% respectively. This study provides much needed data contributions to species sensitivity curves for development of diuron and atrazine water quality guidelines in tropical marine environments.

The effect of copper and temperature on juveniles of the eurybathic brittle star Amphipholis squamata--exploring responses related to motility and the water vascular system.

The limited availability of test organisms that represent tropical and deeper water environments is a significant concern when assessing the risk of contaminants in these environments. Amphipholis squamata (Delle Chiaje 1828) is a widely distributed brittle star with many phylogenetic clades reported from different latitudes, and it also occurs from the intertidal zone to a depth of ∼1300 m. In the present study, the effect of copper on four behavioural responses and mortality of A. squamata were quantified at four different temperatures including 25, 20, 15 and 10°C. At 25°C the four behavioural responses and mortality were relatively sensitive to copper, with 96 h EC50 values of 25 (confidence interval 18-44), 24 (7-26), 32 (24-41), 29 (9-41) µg L(-1) for the measured ability to turn from the oral surface up to oral surface down, curling behaviour, tube foot movement, and tube foot retraction respectively. The average 96-h LC50 value for copper at 25°C was 46 µg L(-1). Some endpoints investigated showed significant effects of reduced temperature compared to the optimal temperature. These effects were enhanced with increasing copper concentrations and significant differences in copper toxicity between temperature treatments were most notable when measuring the ability to turn from the oral surface up to oral surface down where the EC50 changed from 25 (18 to 44) to 6 (-18 to 14) µg L(-1) with a reduction of temperature from 25 to 15°C. The results showed that A. squamata is relatively sensitive to copper and that further investigation into the effects of other stressors on these endpoints is warranted.

Recent mercury contamination from artisanal gold mining on Buru Island, Indonesia--potential future risks to environmental health and food safety.

In November 2011 gold was found at Mount Botak, Buru Island, Mollucas Province, Indonesia. Since 2012 mercury has been used to extract the gold requiring large volumes of water and resulting in deposition of mercury into Wamsait River and Kayeli Bay. Total mercury in waste ponds was over 680 mg/kg. In sediments at the mouth of the local river and a small feeder creek >3.00 mg/kg and >7.66 mg/kg respectively. River and bay sediments were proportionately higher in available mercury than elemental mercury and more strongly bound mercuric sulfide compared to that in trommel waste. This preliminary investigation raises concerns about the long term distribution and speciation of mercury. The floodplain is an important agricultural resource, and Mollucas Province is recognised nationally as the centre for Indonesian fish stocks. Challenges for management include communicating the potential future risks to the community and leaders and identifying mechanisms to reduce mercury waste.

Aiptasia pulchella: a tropical cnidarian representative for laboratory ecotoxicological research.

An urgent need exists to identify suitable tropical marine species for use in the development of sensitive and reliable test methods for routine laboratory ecotoxicological testing. Corals are a group of organisms not represented in routine ecotoxicology due to inherent difficulties in laboratory husbandry, and sea anemones from the same phylum (cnidaria) may be useful proxies. Aiptasia pulchella is a tropical symbiotic sea anemone with a wide geographic range. It is well suited to laboratory conditions and has been used extensively in research. However, its suitability as a toxicity test species has not been investigated. Assessment of juvenile recruitment in laboratory and semi-outdoor conditions showed higher production in semi-outdoor conditions; however, laboratory rearing produced enough recruits to run routine toxicity tests. In investigations of the sensitivity of A. pulchella to contaminants, acute tests were conducted on 1- to 2-mm juveniles using copper. Lethal concentration, 50% (LC50) values at 96 h estimated from tests using five and 10 replicates ranged from 30 to 83 and 60 to 90 µg/L, respectively, and a 28-d LC50 of 26 µg/L was estimated. During the present study, sublethal endpoints were investigated; chronic assessment of inhibited asexual reproduction looks promising (12-d effective concentration, 50% [EC50] 15 µg/L) and should be assessed further. Aiptasia pulchella is a species worthy of investigation as a cnidarian representative, and will be an invaluable contribution to tropical marine ecotoxicologists.