Marine Algal Blooms Research Articles

Structural determinants in phycotoxins and AChBP conferring high affinity binding and nicotinic AChR antagonism

Spirolide and gymnodimine macrocyclic imine phycotoxins belong to an emerging class of chemical agents associated with marine algal blooms and shellfish toxicity. Analysis of 13-desmethyl spirolide C and gymnodimine A by binding and voltage-clamp recordings on muscle-type alpha1(2)betagammadelta and neuronal alpha3beta2 and alpha4beta2 nicotinic acetylcholine receptors reveals subnanomolar affinities, potent antagonism, and limited subtype selectivity. Their binding to acetylcholine-binding proteins (AChBP), as soluble receptor surrogates, exhibits picomolar affinities governed by diffusion-limited association and slow dissociation, accounting for apparent irreversibility. Crystal structures of the phycotoxins bound to Aplysia-AChBP ( approximately 2.4A) show toxins neatly imbedded within the nest of ar-omatic side chains contributed by loops C and F on opposing faces of the subunit interface, and which in physiological conditions accommodates acetylcholine. The structures also point to three major features: (i) the sequence-conserved loop C envelops the bound toxins to maximize surface complementarity; (ii) hydrogen bonding of the protonated imine nitrogen in the toxins with the carbonyl oxygen of loop C Trp147 tethers the toxin core centered within the pocket; and (iii) the spirolide bis-spiroacetal or gymnodimine tetrahydrofuran and their common cyclohexene-butyrolactone further anchor the toxins in apical and membrane directions, along the subunit interface. In contrast, the se-quence-variable loop F only sparingly contributes contact points to preserve the broad receptor subtype recognition unique to phycotoxins compared with other nicotinic antagonists. These data offer unique means for detecting spiroimine toxins in shellfish and identify distinctive ligands, functional determinants and binding regions for the design of new drugs able to target several receptor subtypes with high affinity.

Palynological evidence of synchronous changes within the terrestrial and marine realm at the Triassic/Jurassic boundary (Csővár section, Hungary)

Linking marine and terrestrial events within the end-Triassic extinction is controversial, as is interpretation of carbon cycle perturbation as recorded in carbon isotope excursions. The palynofacies of the Csővár section, Hungary, was studied with the aim of inferring climatic and related vegetation changes within the Triassic/Jurassic boundary interval. The studied section represents a continuous key marine section of the NW Tethyan realm, yielding a typical Late Rhaetian to Hettangian microflora. The most striking feature within the boundary interval is the synchronous peaks of prasinophytes and trilete spores. The co-occurrence of spikes in both the marine and terrestrial signals is described for the first time from a marine boundary section. The prasinophyte and spore peaks also correspond to the previously documented prominent negative carbon isotope excursion and are proposed as a potentially powerful correlation tool. The inferred marine algal bloom and the temporary dominance of ferns in the terrestrial vegetation may signal the biotic response to the same environmental stress, which also affected the carbon cycle. A major perturbation of marine and terrestrial ecosystems is interpreted to be linked to the initial volcanic activity of the Central Atlantic Magmatic Province (CAMP) volcanism.

Characteristics of the marine environment and algal blooms in Gamak Bay

This study was conducted to gain insight into the characteristics of algal blooms in relation to the marine environment of Gamak Bay. From the first known occurrence of algal blooms in 1984 until 2006, 23 causal species have been identified, the most common ones being Prorocentrum sp., Cochlodinium polykrikoides, Chaetoceros sp., Skeletonema costatum, and Heterosigma akashiwo. A principal component analysis indicated that blooms of these species develop under different conditions in terms of water temperature, salinity, precipitation, and insolation. Field data showed Cochlodinium polykrikoides to be favored by high temperatures and to be euryhaline, whereas Skeletonema costatum appeared to be eurythermal and euryhaline. Prorocentrum sp. and Chaetoceros sp. appeared to be stenothermal and stenohaline. Finally, Heterosigma akashiwo appeared at the lowest temperature and highest salinity of the five species and was classified here as stenothermal and stenohaline.

한국 연안에 출현하는 무각와편모조류 5종에 대한 형태 및 분자계통학적 특성

Many species in Gymnodiniales, which are unarmored dinoflagellates, are responsible for marine algal blooms and some of them have potent toxin in the cell. Their taxonomy has so far been well-defined, and several genera (e.g. Akashiwo, Gymnodinium, Karenia) have recently been re-described. In Korea, few works have been carried out on their taxonomical and molecular studies. This study focused on comparison of both morphological and molecular characteristics of five unarmored dinoflagellates on Korean coastal water: Akashiwo sanguinea, Cochlodinium polykrikoides, Gymnodinium catenatum, Gymnodinium impudicum and Karenia aureolum (

Vulnerability of coastal environments to land use and abuse: the example of southeast Florida

The Atlantic coastal zone of subtropical southeast Florida supports nearly 7 million inhabitants. Since the mid‐19th century urbanization intensified along the shore and spread westward into freshwater marshlands. Population densities approaching 2500 persons per km−2 and dredge and fill operations to create urban land in western marshes has degraded coastal environments bringing environmental sustainability into question. Efforts to maintain environmental integrity initially focused on shore protection via ‘hard’ engineering works, which later included massive beach renourishment projects along developed coasts subject to critical erosion. Marine algal blooms, degraded coastal water quality and the deterioration of coral reefs indicate environmental problems more serious than beach erosion. Recognition of a potential eco‐catastrophe prompted the Everglades Restoration Project, the largest single environmental recovery effort in the world. The cleanup of terrestrial systems is essential to sustainability of marine ecosystems now jeopardized by nutrient loading.

Guest Editorial: Satellite Remote Sensing Can Improve Chances of Achieving Sustainable Health

Guest Editorial: Satellite Remote Sensing Can Improve Chances of Achieving Sustainable Health

A review of acid sulfate soil impacts, actions and policies that impact on water quality in Great Barrier Reef catchments, including a case study on remediation at East Trinity

An estimated 666 000 ha of acid sulfate soils (ASS) occur within the Great Barrier Reef (GBR) catchments of Queensland, Australia. Extensive areas have been drained causing acidification, metal contamination, deoxygenation and iron precipitation in reef receiving waters. The close proximity of ASS to reef waters makes them a substantial threat to water quality. Another important issue linked with ASS is their release of soluble iron, which is known to stimulate nuisance marine algal blooms, in particular Lyngbya majuscula. Known blooms of the cyanobacteria in reef waters have been confirmed at Shoalwater Bay, Corio Bay, the Whitsunday area and Hinchinbrook Channel. Acid sulfate soils are intimately related to coastal wetland landscapes. Where landscapes containing ASS have been disturbed (such as for agriculture, aquaculture, marinas, etc.) the biodiversity of adjacent wetlands can be adversely affected. However, there is no clear knowledge of the real extent of the so-called “hotspot” ASS areas that occur within the GBR catchments. Management of ASS in reef catchments has benefited from the implementation of the Queensland Acid Sulfate Soils Management Strategy through policy development, mapping, training programs, an advisory service, research and community participation. However, major gaps remain in mapping the extent and nature of ASS. Areas of significant acidification (i.e. hotspots) need to be identified and policies developed for their remediation. Research has a critical role to play in understanding ASS risk and finding solutions, to prevent the adverse impacts that may be caused by ASS disturbance. A case study is presented of the East Trinity site near Cairns, a failed sugar cane development that episodically discharges large amounts of acid into Trinity Inlet, resulting in periodic fish kills. Details are presented of scientific investigations, and a lime-assisted tidal exchange strategy that are being undertaken to remediate a serious ASS problem.

Public Outreach Materials Regarding Harmful Algal Blooms and Their Possible Effects on Human Health

AbstractThe potential interactions between marine and freshwater harmful algal blooms (HABs) and humans are increasing. Humans are exposed through food, drinking water, and recreational and occupational water use to an increasing number of organisms and their toxins. Nevertheless, the amount of clinical and epidemiologic research concerning acute and chronic human health effects from the HAB organisms and their toxins is relatively sparse. At the same time, the public is increasingly aware of and interested in the potential dangers associated with exposure to HABs. Public health authorities and researchers must respond to these public health concerns. The development of appropriate educational and outreach materials based on limited scientific databases is the challenge of informing the public concerning the possible human health effects of HAB organisms and their toxins, and their prevention. Educational materials developed by a group of researchers and public health personnel for general HABs, Florida Red Tide Toxins (brevetoxins), Cyanobacteria, and Ciguatera are discussed, as well as methods for their dissemination.

Occurrence and distribution of Karenia brevisulcata (Dinophyceae) during the 1998 summer toxic outbreaks on the central east coast of New Zealand

Massive mortality of marine life and algal blooms around central New Zealand during January and March 1998 have been attributed to the toxic dinoflagellate, Karenia brevisulcata (= Gymnodinium brevisulcatum). Phytoplankton surveys in January and February 1998 showed the presence of K. brevisulcata both offshore, in the relatively warm, southwards-directed East Auckland and East Cape Currents, and inshore, in the relatively cold, northwards-directed Wairarapa Coastal Current, along the entire east coast of the North Island. Small numbers of this species (200 cells 1−1) were also recorded on the southwest coast of North Island. A bloom of K. brevisulcata occurred in Wellington Harbour during February–March 1998. Reports of human respiratory distress progressed northwards along the Wairarapa Coast at about the same speed (0.23 m s−1) as observed for the Wairarapa Coastal Current, suggesting the passage of a bloom along the coast. We relate the timing of these events to local oceanographic conditions.

Dinoflagellates from marine algal blooms produce neurotoxic compounds: effects on free calcium levels in neuronal cells and synaptosomes

In this report, evidence is presented that the marine unicellular eukaryotic dinoflagellates can cause neurotoxicity very likely by an increase in intracellular free calcium ions ([Ca 2+] i ). Determinations of the effects of culture supernatants from different clones of the dinoflagellate Alexandrium sp. isolated from algal blooms on the viability of rat primary neuronal cells revealed that all clones tested were toxic for these cells. In addition, all Alexandrium clones tested, except for A. ostenfeldii BAH ME-141, were found to be toxic for rat pheochromocytoma PC12 cells. No toxicity was observed for culture supernatants from Gonyaulax and Coolia monotis. Calcium ions are important in the process of apoptotic cell death; our studies revealed that the dinoflagellate supernatants from A. lusitanicum K2, A. lusitanicum BAH ME-091, and A. tamarense 1M caused an increase in [Ca 2+] i levels in both PC12 cells and primary neuronal cells. These dinoflagellate supernatants, as well as the A. tamarense ccmp 115 supernatant, were found to cause also an increase in free calcium concentration in isolated synaptosomes. Our results suggest that the neurotoxic effects of certain dinoflagellate supernatants may be associated with disturbances in [Ca 2+] i levels.

Changes of ICE protease activities caused by toxic supernatants of dinoflagellates ( Prorocentrum species) from marine algal blooms

Summary Marine phytotoxins may become a major health problem for humans because of their ability to contaminate seafood and to cause shellfish poisoning. In this report, the cytotoxic effects and the effects on intracellular caspase activities of culture supernatants from different dinoflagellate Prorocentrum clones were determined. Among the clones tested, P. tepsium BAH ME-140 and P. lima BAH ME-130 K1 and K2 clones but not P. minimum and P. micans were found to be toxic on rat pheochromocytoma PC12 cells, mouse lymphoma L5178Y cells and rat primary neurons. A significant increase in the specific activities of caspase 1 (ICE), caspase 3 (CPP32) and caspase 6 (Mch2) to 149–167% was observed after treatment of neurons with P. lima BAH ME-130 K2 supernatant for 72 h; in PC 12 cells, the increase in these enzyme activities was much smaller. An even stronger and faster effect on caspase activities, compared to the K2 clone, was observed following treatment of PC12 cells and neuronal cells with P. lima BAH ME-130 Kl supernatant. The maximal increase in caspase activities in PC 12 cells (CPP32, 364%; and Mch2,166%) and in neurons (CPP32,162%; and Mch2,111%) was observed after 24 h; no significant change of ICE activity was found during that incubation period. After 48 h the specific activities of all caspases strongly decreased. Incubation of PC 12 cells with P. tepsium BAH ME-140 for 24 h had almost no effect on caspase activities, while a small increase in CPP32- (148%) and Mch2- (115%) but not in ICE-activity was detected after 48 h. In neurons, only an increase in CPP32 activity (to 130%) was observed with this dinoflagellate supernatant after 24 h. The P lima protein phosphatase inhibitor okadaic acid (0.5 ng/ml) caused a time-dependent increase in caspase activities in PC12 cells. A much higher effect was observed in neuronal cells; after 72 h, the specific activities of ICE, CPP32 and Mch2 increased to 295%, 146% and 235%, respectively. These results indicate that disturbances of caspase activities may contribute to the neurotoxic effects of certain dinoflagellate supernatants.

Discharges from hydroelectric power schemes as a trigger for marine algal blooms

It has been suggested that the occurrence of marine algal blooms world-wide, has increased over the last few decades due in large part to nutrient eutrophication (Smayda, 1990). Specific reference was made to the Skagerrak and Kattegat where reports of unusual blooms (North Sea Task Force, 1993) contributed to their classification as eutrophication ‘Problem Areas’ by the Paris Commission (Oslo and Paris Commissions, 1992). Part of the supporting evidence was based on two exceptional blooms, with associated deoxygenation and fish kills in 1980 and 1981 (Lindahl and Hernroth, 1983; Dahl et al., 1982; Edler, 1984). This paper shows that these blooms coincided with unusually large run-off from rivers regulated by hydroelectric power schemes. Such large freshwater discharge to the sea causes shallow and stable stratification; ideal conditions for rapid phytoplankton growth (Cloern, 1984; Therriault and Levasseur, 1985). These events, as does a similar example in 1982 in France (Rossignol-Strick, 1985), throw in doubt any direct causative relationship with eutrophication, and highlights the need for a careful evaluation of all parameters that are used as assessment criteria for eutrophication problem areas.

A Study of the Effects of the San Francisco Oil Spill on Marine Organisms

ABSTRACT The San Francisco oil spill occurred on January 18, 1971, during the early morning hours when two Standard Oil vessels collided almost directly under the Golden Gate Bridge, releasing 840,000 gallons of Bunker C fuel. This asphalt-like oil was washed up on intertidal shores of the area. Duxbury Reef, northwest of the Golden Gate Bridge, is literally the “backyard” of the author and the College of Marin's Bolinas Marine Station staff. Baseline transects have been established on this reef since 1958. The oil was heavily deposited on the reef's mussel beds and high tidal berm rocks. From comparative transect and laboratory observations, it was determined that marine organisms died from being smothered by the oil, with certain species, such as acorn barnacles and limpets, suffering the highest mortality at Sausalito and on Duxbury Reef. Comparison of pre-oil and post-oil transect counts showed there was a significant decrease in marine life after the oil spill on the reef Marine snails suffered less mortality than the sessile barnacles and other sedentary animals. The normally large population of striped shore crabs is missing from the rocky crevices. Finally, marine algal blooms were also observed in certain reef localities. The present condition of Duxbury Reef (December, 1971) is one of apparent good health; the recruitment of some marine animals appear to be approaching normal levels. The oil has disappeared from much of the reef surfaces and is barely discernible in the most heavily deluged areas. Continued studies will be aimed at watching the effects of oil on the recruitment of marine life throughout the afflicted areas of the Marin County coastline.