Decreased surface and bottom salinity and elevated bottom temperature in the Northern Baltic Sea over the past six decades.

Temperature and salinity are key factors in controlling marine habitats and gas fluxes. Finnish and Swedish temperature and salinity monitoring data from the northern Baltic Sea since the 1960s, and Argo buoy data from the eastern Gotland Basin and the Bothnian Sea from 2012 to 2021 were examined using linear trend analysis. Since the 1960's near-bottom temperature has increased by 0.75-2.9 °C (0.013-0.115 °C/a) and surface salinity declined by 0.31-1.14 units (0.005-0.019/a). Surface temperature trends at monitoring stations were negative (16 cases out of 33) but deemed unreliable. Near-bottom salinity has declined by 0.35-1.45 units (0.007-0.025/a), except in the northern Baltic Proper and the central-eastern Gulf of Finland. Most rapid increases in near-bottom temperature have occurred after 1993, especially in the northern Baltic Proper and the Gulf of Finland. Argo data corroborated declining surface salinity in the eastern Gotland Basin, increasing deep-water temperature in the eastern Gotland Basin and the Bothnian Sea and increasing deep-water salinity in the eastern Gotland Basin. Argo data from 2013 to 2021 indicated deep-water temperature increase in the Gotland basin was more rapid than the concomitant salinity increase and is probably related to global change.

Rapid and Highly Sensitive Non-Competitive Immunoassay for Specific Detection of Nodularin.

Nodularin (NOD) is a cyclic penta-peptide hepatotoxin mainly produced by Nodularia spumigena, reported from the brackish water bodies of various parts of the world. It can accumulate in the food chain and, for safety reasons, levels of NOD not only in water bodies but also in food matrices are of interest. Here, we report on a non-competitive immunoassay for the specific detection of NOD. A phage display technique was utilized to interrogate a synthetic antibody phage library for binders recognizing NOD bound to an anti-ADDA (3-Amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4(E),6(E)-dienoic acid) monoclonal antibody (Mab). One of the obtained immunocomplex binders, designated SA32C11, showed very high specificity towards nodularin-R (NOD-R) over to the tested 10 different microcystins (microcystin-LR, -dmLR, -RR, -dmRR, -YR, -LY, -LF, -LW, -LA, -WR). It was expressed in Escherichia coli as a single chain antibody fragment (scFv) fusion protein and used to establish a time-resolved fluorometry-based assay in combination with the anti-ADDA Mab. The detection limit (blank + 3SD) of the immunoassay, with a total assay time of 1 h 10 min, is 0.03 µg/L of NOD-R. This represents the most sensitive immunoassay method for the specific detection of NOD reported so far. The assay was tested for its performance to detect NOD using spiked (0.1 to 3 µg/L of NOD-R) water samples including brackish sea and coastal water and the recovery ranged from 79 to 127%. Furthermore, a panel of environmental samples, including water from different sources, fish and other marine tissue specimens, were analyzed for NOD using the assay. The assay has potential as a rapid screening tool for the analysis of a large number of water samples for the presence of NOD. It can also find applications in the analysis of the bioaccumulation of NOD in marine organisms and in the food chain.

[Harmful algae and health]. / Haitalliset levät ja terveys.

Harmful algae are a worldwide problem. Phycotoxins is a general term for toxic compounds produced by harmful species of the phytoplankton. This review deals with the occurrence of harmful algae and phycotoxins in the Baltic Sea and other domestic waters, the ways of getting exposed to them, and their effects. Advice on how to avoid the exposure is provided.

Production and sedimentation of peptide toxins nodularin-R and microcystin-LR in the northern Baltic Sea.

This seven-year survey was primarily targeted to quantification of production of nodularin-R (NOD-R), a cyclic pentapeptide hepatotoxin, in Baltic Sea cyanobacteria waterblooms. Additionally, NOD-R and microcystin-LR (MC-LR; a cyclic heptapeptide toxin) sedimentation rates and NOD-R sediment storage were estimated. NOD-R production (70-2450 microg m(-3); approximately 1 kg km(-2) per season) and sedimentation rates (particles; 0.03-5.7 microg m(-2)d(-1); approximately 0.3kg km(-2) per season) were highly variable over space and time. Cell numbers of Nodularia spumigena did not correlate with NOD-R quantities. Dissolved NOD-R comprised 57-100% of total NOD-R in the predominantly senescent, low-intensity phytoplankton blooms and seston. Unprecedentedly intensive MC-LR sedimentation (0.56 microg m(-2)d(-1)) occurred in 2004. Hepatotoxin sedimentation rates highly exceeded those of anthropogenic xenobiotics. NOD-R storage in surficial sediments was 0.4-20 microg kg(-1) ( approximately 0.1 kg km(-2)). Loss of NOD-R within the chain consisting of phytoplankton, seston and soft sediments seemed very effective.

Cyanobacteria and prawn farming in northern New South Wales, Australia--a case study on cyanobacteria diversity and hepatotoxin bioaccumulation.

Harmful cyanobacteria pose a hazard to aquatic ecosystems due to toxins (hepatotoxic microcystins, nodularins, and cylindrospermopsin) they produce. The microcystins and nodularins are potent toxins, which are also tumor promoters. The microcystins and nodularins may accumulate into aquatic organisms and be transferred to higher trophic levels, and eventually affect vector animals and consumers. Prawn farming is a rapidly growing industry in Australia. Because information regarding effects of cyanobacteria at prawn farms was lacking, we examined diversity of cyanobacteria and toxin production plus bioaccumulation into black tiger prawns (Penaeus monodon) under both field (northern New South Wales, Australia, December 2001-April 2002) and laboratory conditions. Samples were analyzed for hepatotoxins using enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The maximum density of cyanobacteria (1 x 10(6) to 4 x 10(6) cells/l) was reached in April. Cyanobacteria encountered were Oscillatoria sp. (up to 4 x 10(6) cells/l), Pseudanabaena sp. (up to 1.8 x 10(6) cells/l), Microcystis sp. (up to 3.5 x 10(4) cells/l), and Aphanocapsa sp. (up to 2 x 10(4) cells/l). An uncommon cyanobacterium, Romeria sp. (up to 2.2 x 10(6) cells/l), was also observed. Contrasting earlier indications, toxic Nodularia spumigena was absent. Despite that both Oscillatoria sp. and Microcystis sp. are potentially hepatotoxic, hepatotoxin levels in phytoplankton samples remained low (up to 0.5-1.2 mg/kg dw; ELISA) in 2001-2002. ELISA was found suitable not only for phytoplankton but prawn tissues as well. Enzymatic pretreatment improved extractability of hepatotoxin from cyanobacteria (nodularin from N. spumigena as an example), but did not generally increase toxin recovery from prawn hepatopancreas. There were slightly increasing hepatotoxin concentrations in prawn hepatopancreas (from 6-20 to 20-80 microg/kg dw; ELISA) during the study. Hepatotoxin concentrations in surface sediment remained low (<5 microg/kg dw; ELISA) throughout the study. Laboratory experiments indicated that prawn hepatopancreas, heart, and brain were primary organs for hepatotoxin bioaccumulation. Toxin concentration in other organs, including muscle, was less effective. Orally administered nodularin levels in hepatopancreas rapidly decreased from initial 830 to 250 microg/kg dw in 96 h. Similarly, concentration of microcystin-LR injected in prawns decreased from 130 to 30 microg/kg dw (hepatopancreas) in 2 h. These results demonstrate that potential risks caused by cyanobacteria in prawn farming (farmers, prawns, and consumers) were not substantial in 2001-2002. Although prawns may act as vectors for toxin transfer, they did not accumulate alerting amounts of hepatotoxins and were able to effectively detoxify them. Because bloom toxicity may vary, low-frequency toxin monitoring is recommended.

Eiders (Somateria mollissima) obtain nodularin, a cyanobacterial hepatotoxin, in Baltic Sea food web.

Nodularin (NODLN) is a cyclic pentapeptide hepatotoxin produced by the cyanobacterium Nodularia spumigena, which occurs regularly in the Baltic Sea during the summer season. Nodularia blooms have caused several animal kills in the Baltic Sea area, and NODLN has been found in mussels and fish caught from the northern Baltic Sea in 1996 to 2002. We analyzed liver samples of common eider (Somateria mollissima) for NODLN by enzyme-linked immunosorbent assay (ELISA) and liquid chromatography/mass spectrometry (LC-MS). Eiders feed extensively on mussel and can be exposed to NODLN by contaminated mussels. Fifteen eiders were shot and collected from three different sites in the western Gulf of Finland (northern Baltic Sea) in August and September 2002. Analyses by ELISA and LC-MS showed that eider liver samples contained 3 to 180 microg NODLN/kg dry weight and 0.1 to 5.8 microg NODLN/liver (dry wt). This is the first documentation of NODLN in seabirds and additional evidence for the transfer of NODLN in different parts of the Baltic Sea food web.