First Report of a Toxic Nodularia spumigena (Nostocales/Cyanobacteria) Bloom in Sub-Tropical Australia. II. Bioaccumulation of Nodularin in Isolated Populations of Mullet (Mugilidae)

Fish collected after a mass mortality at an artificial lake in south-east Queensland, Australia, were examined for the presence of nodularin as the lake had earlier been affected by a Nodularia bloom. Methanol extracts of muscle, liver, peritoneal and stomach contents were analysed by HPLC and tandem mass spectrometry; histological examination was conducted on livers from captured mullet. Livers of sea mullet (Mugil cephalus) involved in the fish kill contained high concentrations of nodularin (median 43.6 mg/kg, range 40.8-47.8 mg/kg dry weight; n = 3) and the toxin was also present in muscle tissue (median 44.0 mu g/kg, range 32.3-56.8 mu g/kg dry weight). Livers of fish occupying higher trophic levels accumulated much lower concentrations. Mullet captured from the lake 10 months later were also found to have high hepatic nodularin levels. DNA sequencing of mullet specimens revealed two species inhabiting the study lake: M. cephalus and an unidentified mugilid. The two mullet species appear to differ in their exposure and/or uptake of nodularin, with M. cephalus demonstrating higher tissue concentrations. The feeding ecology of mullet would appear to explain the unusual capacity of these fish to concentrate nodularin in their livers; these findings may have public health implications for mullet fisheries and aquaculture production where toxic cyanobacteria blooms affect source waters. This report incorporates a systematic review of the literature on nodularin measured in edible fish, shellfish and crustaceans.

Chemical characteristics and behaviour of sediment phosphorus in the northeastern Baltic Sea.

Chemical characteristics and behaviour of sediment phosphorus in the northeastern Baltic Sea Eutrophication is a severe environmental problem in the Baltic Sea, especially in the Gulf of Finland and the Archipelago Sea, and it is enhanced by the release of phosphorus (P) from bottom sediments. The release of P from sediment reserves largely depends on the occurrence of P in different chemical forms and on the prevailing conditions, especially on the presence of oxygen. This study examines the chemical character and the vertical distribution of sediment P in two shallow estuaries, in shallow coastal sediments overlain by oxic near-bottom water, and in poorly oxygenated open sea sediments in the northeastern Baltic Sea. The objective was to evaluate how much of the sediment P is buried and removed from the nutrient cycle, and how much of it is in forms that can be released from the sediment to the overlaying water over time. Relationships between the distribution of the different P forms and the chemical and physical properties of the sediment, sediment pore water, and near-bottom water were determined in order to examine the behaviour of P at the sediment-water interface. The results show that the chemical character of sediment P varied in the different areas. Generally, in the outer estuaries and in the organic-rich coastal areas in the eastern Gulf of Finland, the sediments were higher in P than the sediments in the poorly oxygenated open sea areas in the central and western Gulf. The estuary sediments that received erosion-transported material were characterised by P bound to hydrated oxides of iron and aluminum. Iron-bound P is sensitive to changes in redox-conditions, but part of it was buried in the estuaries, possibly because of high sedimentation rates and incomplete reduction of iron. The open sea sediments in the central and western Gulf of Finland were dominated by apatite-P, which was also abundant in the areas strongly affected by sediment transportation. The burial of sediment P was most effective in the areas rich in apatite-P, which is a relatively stable form of P in sediment. In the eastern Gulf of Finland, organic P forms predominated in the organic-rich sediments. A part of these P forms will be buried, while part will be degraded in the long term, releasing soluble P to the pore water. In the poorly oxygenated areas, iron compounds at the sediment surface are not able to retain P released during mineralisation of organic matter or reduction-induced dissolution of iron-compounds in deep sediment layers. However, in the shallow coastal areas overlain by oxic near-bottom water, the organic-rich surface sediment can also become temporarily reduced and release P from the sediment to the overlaying water. The considerable variation in the chemical composition of sediment P reserves in the northeastern Baltic Sea proved that it is an important factor and should be taken into account when evaluating the release of sediment P and the role of P reserves in bottom sediments in eutrophication.

A review of the application of molecular genetics for fisheries management and conservation of sharks and rays

Since the first investigation 25 years ago, the application of genetic tools to address ecological and evolutionary questions in elasmobranch studies has greatly expanded. Major developments in genetic theory as well as in the availability, cost effectiveness and resolution of genetic markers were instrumental for particularly rapid progress over the last 10 years. Genetic studies of elasmobranchs are of direct importance and have application to fisheries management and conservation issues such as the definition of management units and identification of species from fins. In the future, increased application of the most recent and emerging technologies will enable accelerated genetic data production and the development of new markers at reduced costs, paving the way for a paradigm shift from gene to genome-scale research, and more focus on adaptive rather than just neutral variation. Current literature is reviewed in six fields of elasmobranch molecular genetics relevant to fisheries and conservation management (species identification, phylogeography, philopatry, genetic effective population size, molecular evolutionary rate and emerging methods). Where possible, examples from the Indo-Pacific region, which has been underrepresented in previous reviews, are emphasized within a global perspective. (C) 2012 The Authors Journal of Fish Biology (C) 2012 The Fisheries Society of the British Isles

Searching for common threads in threadfins: phylogeography of Australian polynemids in space and time

Proper management of marine fisheries requires an understanding of the spatial and temporal dynamics of marine populations, which can be obtained from genetic data. While numerous fisheries species have been surveyed for spatial genetic patterns, temporally sampled genetic data is not available for many species. We present a phylogeographic survey of the king threadfin Polydactylus macrochir across its species range in northern Australia and at a temporal scale of 1 and 10 yr. Spatially, the overall AMOVA fixation index was Omega(st) = 0.306 (F-st' = 0.838), p < 0.0001 and isolation by distance was strong and significant (r(2) = 0.45, p < 0.001). Temporally, genetic patterns were stable at a time scale of 10 yr. However, this did not hold true for samples from the eastern Gulf of Carpentaria, where populations showed a greater degree of temporal instability and lacked spatial genetic structure. Temporal but not spatial genetic structure in the Gulf indicates demographic interdependence but also indicates that fishing pressure may be high in this area. Generally, genetic patterns were similar to another co-distributed threadfin species Eleutheronema tetradactylum, which is ecologically similar. However, the historical demography of both species, evaluated herein, differed, with populations of P. macrochir being much younger. The data are consistent with an acute population bottleneck at the last glacio-eustatic low in sea level and indicate that the king threadfin may be sensitive to habitat disturbances.

Fish mediate high food web connectivity in the lower reaches of a tropical floodplain river

High levels of hydrological connectivity during seasonal flooding provide significant opportunities for movements of fish between rivers and their floodplains, estuaries and the sea, possibly mediating food web subsidies among habitats. To determine the degree of utilisation of food sources from different habitats in a tropical river with a short floodplain inundation duration (similar to 2 months), stable isotope ratios in fishes and their available food were measured from three habitats (inundated floodplain, dry season freshwater, coastal marine) in the lower reaches of the Mitchell River, Queensland (Australia). Floodplain food sources constituted the majority of the diet of large-bodied fishes (barramundi Lates calcarifer, catfish Neoarius graeffei) captured on the floodplain in the wet season and for gonadal tissues of a common herbivorous fish (gizzard shad Nematalosa come), the latter suggesting that critical reproductive phases are fuelled by floodplain production. Floodplain food sources also subsidised barramundi from the recreational fishery in adjacent coastal and estuarine areas, and the broader fish community from a freshwater lagoon. These findings highlight the importance of the floodplain in supporting the production of large fishes in spite of the episodic nature and relatively short duration of inundation compared to large river floodplains of humid tropical regions. They also illustrate the high degree of food web connectivity mediated by mobile fish in this system in the absence of human modification, and point to the potential consequences of water resource development that may reduce or eliminate hydrological connectivity between the river and its floodplain.

Genetic diversity and microcystin production by Anabaena in the Gulf of Finland, Baltic Sea

Syanobakteerit (sinilevät) ovat olleet Itämeressä koko nykymuotoisen Itämeren ajan, sillä paleolimnologiset todisteet niiden olemassaolosta Itämeren alueella ovat noin 7000 vuoden takaa. Syanobakteerien massaesiintymät eli kukinnat ovat kuitenkin sekä levinneet laajemmille alueille että tulleet voimakkaimmiksi viimeisten vuosikymmenien aikana. Tähän on osasyynä ihmisten aiheuttama kuormitus, joka rehevöittää Itämerta. Suomenlahti, jota tämä tutkimus käsittelee, on kärsinyt tästä rehevöitymiskehityksestä muita Itämeren altaita enemmän. Syanobakteerit muodostavat jokakesäisiä kukintoja Suomenlahdella - niin sen avomerialueilla kuin rannoillakin. Yleisimmät kukintoja muodostavat syanobakteerisuvut ovat Nodularia, Anabaena ja Aphanizomenon. Kukinnat aiheuttavat paitsi esteettistä haittaa myös terveydellisen riskitekijän. Niiden myrkyllisyys liitetään usein Nodularia-suvun tuottamaan nodulariini-maksamyrkkyyn. Itämeren Aphanizomenon-suvun on todettu olevan myrkytön. Vaikka Itämeren kukintoja aiheuttavista Nodularia- ja Aphanizomenon-syanobakteereista tiedetään varsin paljon, on molekyylimenetelmiin pohjautuva syanobakteeritutkimus ohittanut Itämeren Anabaena-suvun monelta osin. Tämän työn tarkoituksena oli syventää käsitystämme Itämeren Anabaena-syanobakteerista, sen mahdollisesta myrkyllisyydestä, geneettisestä monimuotoisuudesta ja fylogeneettisista sukulaisuussuhteista. Tässä työssä eristettiin 49 planktista Anabaena-kantaa, joista viisi tuottivat mikrokystiinejä. Tämä oli ensimmäinen yksiselitteinen todiste, että Itämeren Anabaena tuottaa maksamyrkyllisiä mikrokystiini-yhdisteitä. Jokainen eristetty myrkyllinen Anabaena-kanta tuotti useita mikrokystiini-variantteja. Lisäksi mikrokystiinejä löydettiin kukintanäytteistä, joissa oli myrkkyä syntetisoivia geenejä sisältäneitä Anabaena-syanobakteereita. Myrkkyjä löydettiin molempina tutkimusvuosina 2003 ja 2004. Myrkkyjen esiintyminen ei siten ollut vain yksittäinen ilmiö. Tässä työssä saimme viitteitä siitä, että maksamyrkyllinen Anabaena-syanobakteeri esiintyisi vähäsuolaisissa vesissä. Tämä riippuvuussuhde jää kuitenkin tulevien tutkimuksien selvitettäväksi. Tässä työssä havaittiin mikrokystiinisyntetaasi-geenien inaktivoituminen Itämeren Anabaena-kannassa ja kukintanäytteissä. Kuvasimme Anabaena-kannan mikrokystiinisyntetaasigeenien sisältä insertioita, jotka hyvin todennäköisesti inaktivoivat myrkyntuoton. Insertion sisältäneeltä kannalta löysimme kuitenkin kaikki mikrokystiinisyntetaasigeenit osoittaen, että geenien olemassaolo ei välttämättä varmista kannan mikrokystiinintuottoa. Mielenkiintoista oli se, että inaktivaation aiheuttavia insertioita löytyi kukintanäytteistä molemmilta tutkimusvuosilta. Vastaavia insertioita ei kuitenkaan löydetty makean veden Anabaena-kannoista tai järvinäytteistä. On yleistä, että syanobakteerikukinnoista löytyy usean syanobakteerisuvun edustajia. Myrkyllisiä sukuja tai lajeja ei voida kuitenkaan erottaa mikroskooppisesti myrkyttömistä. Käsillä olevassa tutkimuksessa kehitettiin molekyylimenetelmä, jolla on mahdollista määrittää kukinnan mahdollisesti maksamyrkylliset syanobakteerisuvut. Tätä menetelmää sovellettiin Itämeren kukintojen tutkimiseen. Itämeren pintavesistä ja ranta-alueiden pohjasta eristetyt Anabaena-kannat osoittautuivat geneettisesti monimuotoisiksi. Tämä Anabaena-syanobakteerien geneettinen monimuotoisuus vahvistettiin monistamalla geenejä suoraan kukintanäytteistä ilman kantojen eristystä. Makeiden vesien ja Itämeren Anabaena-kannat ovat geneettisesti hyvin samankaltaisia. Geneettisissä vertailuissa kävi kuitenkin ilmi, että pohjassa elävien Anabaena-kantojen geneettinen monimuotoisuus oli suurempaa kuin pintavesistä eristettyjen kantojen. Itämeren Anabaena-kantojen sekvenssit muodostivat omia ryhmiä sukupuun sisällä, jolloin on mahdollista, että nämä edustavat Itämeren omia Anabaena-ekotyyppejä. Tämä tutkimus oli ensimmäinen, jossa uusin molekyylimenetelmin systemaattisesti selvitettiin Itämeren Anabaena-syanobakteerin geneettistä populaatiorakennetta, fylogeniaa ja myrkyntuottoa. Tulevaisuudessa monitorointitutkimuksissa on otettava huomioon myös Itämeren Anabaena-syanobakteerin mahdollinen maksamyrkyntuotto – erityisesti vähäsuolaisemmilla rannikkovesillä.

Essays on the Bioeconomics of the Northern Baltic Fisheries

World marine fisheries suffer from economic and biological overfishing: too many vessels are harvesting too few fish stocks. Fisheries economics has explained the causes of overfishing and provided a theoretical background for management systems capable of solving the problem. Yet only a few examples of fisheries managed by the principles of the bioeconomic theory exist. With the aim of bridging the gap between the actual fish stock assessment models used to provide management advice and economic optimisation models, the thesis explores economically sound harvesting from national and international perspectives. Using data calibrated for the Baltic salmon and herring stocks, optimal harvesting policies are outlined using numerical methods. First, the thesis focuses on the socially optimal harvest of a single salmon stock by commercial and recreational fisheries. The results obtained using dynamic programming show that the optimal fishery configuration would be to close down three out of the five studied fisheries. The result is robust to stock size fluctuations. Compared to a base case situation, the optimal fleet structure would yield a slight decrease in the commercial catch, but a recreational catch that is nearly seven times higher. As a result, the expected economic net benefits from the fishery would increase nearly 60%, and the expected number of juvenile salmon (smolt) would increase by 30%. Second, the thesis explores the management of multiple salmon stocks in an international framework. Non-cooperative and cooperative game theory are used to demonstrate different "what if" scenarios. The results of the four player game suggest that, despite the commonly agreed fishing quota, the behaviour of the countries has been closer to non-cooperation than cooperation. Cooperation would more than double the net benefits from the fishery compared to a past fisheries policy. Side payments, however, are a prerequisite for a cooperative solution. Third, the thesis applies coalitional games in the partition function form to study whether the cooperative solution would be stable despite the potential presence of positive externalities. The results show that the cooperation of two out of four studied countries can be stable. Compared to a past fisheries policy, a stable coalition structure would provide substantial economic benefits. Nevertheless, the status of the salmon stocks would not improve significantly. Fourth, the thesis studies the prerequisites for and potential consequences of the implementation of an individual transferable quota (ITQ) system in the Finnish herring fishery. Simulation results suggest that ITQs would result in a decrease in the number of fishing vessels, but enables positive profits to overlap with a higher stock size. The empirical findings of the thesis affirm that the profitability of the studied fisheries could be improved. The evidence, however, indicates that incentives for free riding exist, and thus the most preferable outcome both in economic and biological terms is elusive.

Arnon River - Dead Sea

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Organic contaminants - occurrence and biological effects in the Baltic Sea

The Baltic Sea was studied with respect to selected organic contaminants and their ecotoxicology. The research consisted of analyses of total hydrocarbons, polycyclic aromatic hydrocarbons, bile metabolites, hepatic ethoxyresorufin-O-deethylase (EROD) activity, polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). The contaminants were measured from various matrices, such as seawater, sediment and biota. The methods of analysis were evaluated and refined to comparability of the results. Polyaromatic hydrocarbons, originating from petroleum, are known to be among the most harmful substances to the marine environment. In Baltic subsurface water, seasonal dependence of the total hydrocarbon concentrations (THCs) was seen. Although concentrations of parent polycyclic aromatic hydrocarbons (PAHs) in sediment surface varied between 64 and 5161 ug kg-1 (dw), concentrations above 860 ug kg-1 (dw) were found in all the studied sub-basins of the Baltic Sea. Concentrations commonly considered to substantially increase the risk of liver disease and reproductive impairment in fish, as well as potential effects on growth (above 1000 ug kg-1 dw), were found in all the studied sub-basins of the Baltic Sea except Kattegat. Thus, considerable pollution in sediments was indicated. In bivalves, the sums of 12 PAHs varied on a wet weight basis between 44 and 298 ug kg-1 (ww). The predominant PAHs were high molecular weight and the PAH profiles of M. balthica differed from those found in sediment from the same area. The PAHs were both pyrolytic and petrogenic in origin, and a contribution from diesel engines was found, which indicates pollution of the Baltic Sea, most likely caused by the steadily increasing shipping in the area. The HPLC methods developed for hepatic EROD activity and bile metabolite measurements proved to be fast and suitable for the study of biological effects. A mixed function oxygenase enzyme system in Baltic Sea perch collected from the Gulf of Finland was induced slightly: EROD activity in perch varied from 0.30 14 pmol min-1 mg-1 protein. This range can be considered to be comparable to background values. Recent PAH exposure was also indicated by enhanced levels (213 and 1149 ug kg-1) of the bile metabolite 1-hydroxypyrene. No correlation was indicated between hepatic EROD activity and concentration of 1-hydroxypyrene in bile. PCBs and OCPs were observed in Baltic Sea sediment, bivalves and herring. Sums of seven CBs in surface sediment (0 5 cm) ranged from 0.04 to 6.2 ug kg-1 (dw) and sums of three DDTs from 0.13 to 5.0 ug kg-1 (dw). The highest levels of contaminants were found in the most eastern area of the Gulf of Finland where the highest total carbon and nitrogen content was found and where the lowest percentage proportion of p,p -DDT was found. The highest concentrations of CBs and the lowest concentration of DDTs were found in M. balthica from the Gulf of Finland. The highest levels of DDTs were found in M. balthica from the Hanö Bight, which is the outer part of the Bornholm Basin close to the Swedish mainland. In bivalves, the sums of seven CBs were 72 108 ug kg-1 (lw) and the sums of three DDTs were 66 139 ug kg-1 (lw). Results from temporal trend monitoring showed, that during the period 1985 2002, the concentrations of seven CBs in two-year-old female Baltic herring were clearly decreased, from 9 16 to 2 6 ug kg-1 (ww) in the northern Baltic Sea. At the same time, concentrations of three DDTs declined from 8 15 to 1 5 ug kg-1 (ww). The total concentration of the fat-soluble CBs and DDTs in Baltic herring muscle was shown to be age-dependent; the average concentrations in ten-year-old Baltic herring were three to five-fold higher than in two-year-old herring. In Baltic herring and bivalves, as well as in surface sediments, CB 138 and CB153 were predominant among CBs, whereas among DDTs p,p'-DDD predominated in sediment and p,p'-DDE in bivalves and Baltic herring muscle. Baltic Sea sediments are potential sources of contaminants that may become available for bioaccumulation. Based on ecotoxicological assessment criteria, cause for concern regarding CBs in sediments was indicated for the Gulf of Finland and the northern Baltic Proper, and for the northern Baltic Sea regarding CBs in Baltic herring more than two years old. Statistical classification of selected organic contaminants indicated high-level contamination for p,p'-DDT, p,p'-DDD, p,p'-DDE, total DDTs, HCB, CB118 and CB153 in muscle of Baltic herring in age groups two to ten years; in contrast, concentrations of a-HCH and g-HCH were found to be moderate. The concentrations of DDTs and CBs in bivalves is sufficient to cause biological effects, and demonstrates that long-term biological effects are still possible in the case of DDTs in the Hanö Bight.