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Mercury in biota in the Tyrrhenian SeaPilot Study 2011 MEDOCEANOR Project Fenice workshop, March 27, 2012 Oksana Lane, David Evers Biodiversity Research Institute, Maine and Kate Buckman- Dartmouth college, New Hampshire, USA
Pelagic Food Web +suro
Outline • Surface water sampling/results • Zooplankton sampling/results • Megafauna: fish and calamari sampling/results • Human hair on board Urania results
Taxa collected • Zooplankton: copepods, euphausiids, salps • Tiny fish (1-2 cm); lantern fish • Benthic invertebrates: annalida, etc • Cephalopods: calamari and totano • Predatory fish-Suro=Mediterranean Horse Mackerel • Fish from the stomachs of Suro • Human hair on board Urania • Also filtered water samples were analyzed
Surface water results • Hg in filtered surface water was below detection limits for all sites • Dissolved Cd, Pb, Sn, Zn, & Cu all below reporting limits • Measurable dissolved As & Se, As but not Se different across sites • Preliminary analyses of particulates were near detection limits for MeHg & inorganic Hg, needs additional sample analysis
Collection methods-Zooplankton • Neuston net-1/2 x 1 x 5m; day and night time towing • Twin ring net (60cm diameter); for water column sampling
Zooplankton Neat-looking things • Euphausiid • Isopods and megalope Photos by Kate Buckman
Results: Hg speciation in Zooplankton • To our knowledge, this is the first measurement of Hg & MeHg in field sampled zooplankton from the Mediterranean, as well as the first measures on euphausiids. • Euphausiids eat phytoplankton and small zooplankton and likely have slightly higher trophic status than the small fish. Life span~1 month. • 3 composite samples per site, alpha = 0.05, Tukey’s HSD used to assess pairwise differences.
Mediterranean horse mackerel=Suro(Trachurusmediterraneus) • Carnivore • Diet: zooplankton=Crustacea: Euphausiids, Mysidacea, Decapods Teleostei (fish) and Cephalopoda (calamari) Polychaeta (annelid worms) • Important commercially Stomach contents of Suro, October 2011.
Squid=Calamari, totano • Cephalopods (phylum: molluska) • Predator • Important food source for marine mammals, fish, humans • Diet: fish, crustaceans, other squids
THg concentrations (µg/kg=ppb) 2011in 3 taxa from Livorno. Maximum Mean + Standard Deviation Adult 30% reduction Juvenile 20% 10% DUNL SESA ROSA REPH Figure 2. Blood Hg concentrations in Alaskan shorebirds. Lines show blood mercury levels associated with 10% (0.7 μg/g), 20% (1.2 μg/g), 30% (1.7 μg/g) reduced nesting success based on the Carolina wren model. All juveniles and adult ROSA sampled during migration; adult DUNL, REPH, and SESA sampled during breeding season at Barrow, AK. ROSA = rock sandpiper, DUNL= dunlin, REPH= red phalarope, SESA= semipalmated sandpiper.
Mean THg in Suro muscle( wet wt. ppm) • Wilcoxonnonparametric test: Piombino >Ustica, p=0.0085; Livorno >Ustica, p=0.052 • Red line represents 0.3 ppm=recommended (by US EPA)upper level for human consumption of contaminated fish and wildlife. • Dashed yellow line represents 0.15 ppm=threshold level for piscivorous wildlife
Suro size Fish length in cm of Mackerel (Suro) analyzed for Hg, 2011. There is no statistical difference in fish length among sites, p>0.1
Comparison of calamari/totano Hg (µg/g, fw) by site, 2011 Over 90% of total Hg was MeHg in mackerel and calamari. Piombino is significantly higher than other sites, p<0.05. (number)=sample size analyzed
Hg speciation in Megafauna • Mackerel are skin-off tissue plugs, squid are tentacles only, n = 3 for all • Mackerel & calamari from Livorno, totano from Open Sea 1 • No significant differences between species of edible megafauna
Additional zooplankton taxa collected Shrimp (large in center), euphausiids, hyperiid amphipod, mysid, copepod amphipods
Sediment dwelling benthic macroinvertebrates Digging for gold
Hair Hg concentrations in crew and scientists on board Urania, November 2011 • Hair Hg in Italians ranged from 924 to 7690 ppb. • Over 2000 ppb is considered elevated and at higher risk to heart attack, risk is greater in smokers • 1000 ppb, a level that corresponds with the exposure limit • recommended by the National Research Council committee, 2000.
Summary of Findings • Mackerel from Piombino area have tissue wwTHg concentrations (over 300 ppb) reaching wildlife “effect” levels • Mackerel and calamari from Piombino site have significantly higher muscle THg concentrations than from other sampled sites • Euphausiids appear to be a good indicator species and are more appropriate than tiny smelt fish. MeHg in euphausiids on average is~ 81% vs. 57% in small fish. They are an important food species and are likely contributing to the higher MeHg in larger fish at industrial sites. • Hair THg concentrations in Urania crew are elevated. It could be attributed to eating swordfish=pescespada (Xiphiasgladius). Swordfish is known to have high Hg concentrations (over 1.5 ppmww) and was served twice on board Urania during the 2-week mission.
Potential future analysis • Particulates • Copepods • Amphipods • Mysids • Euphausiids from additional sites • Stable C & N for trophic analysis
Recommendations • Continue sampling euphausiids, mackerel and calamari throughout Mediterranean Sea to characterize Hg exposure in biota. • Sample along a transect downwind and downstream of the industrial sites to establish the spatial impact of the contamination (i.e., the “Footprint”) • Link biota Hg concentrations with air and water Hg data • Create a map of Hg “hot spots” of fish/calamari for the Mediterranean Sea.