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In the Northern Alboran Sea, artisanal small-scale fisheries using trammel nets suffer economic losses, and local fishermen see their way-of-life endangered, due to interactions with wildlife species such as alien species and dolphins. On the one hand, the alien seaweed Rugulopteryx okamurae, which was first recorded in the Alboran Sea in 2015, has undergone an intensive expansion in the sub-region, monopolizing the available seabed, causing radical changes in the underwater seascape and clogging the trammel nets. On the other hand, the damage caused to the fishing nets by dolphin fish predation is an ancient problem worldwide, but it is intensifying in the last years. The main objective of this study is to understand the main environmental and technical conditions that favor damages of fishing trammel nets in the Alboran Sea, which entails an important loss of catchability, due to (i) the clogging of the artisanal fishing trammel nets by invasive seaweed, and (ii) the breaking of the nets by dolphin predation. Through close monitoring of fishermen in port, we obtained direct information of 548 sets. Our results indicate that approximately 30% of trammel sets suffered a damage due to unwanted interaction with alien seaweeds and dolphins. As seaweeds invasion is a global problem while dolphin-fishing gear interaction is more local, we concluded that only a large-scale management of exotic algae, together with the involvement of local fishermen, could solve the economic problems of this activity. [ABSTRACT FROM AUTHOR]

Here, we report the draft genome of Aureococcus anophagefferens strain CCMP1851, which is susceptible to the virus Kratosvirus quantuckense . CCMP1851 complements an available genome for a virus-resistant strain (CCMP1850) isolated from the same bloom. Future studies can now use this genome to examine genetic hints of virus resistance and susceptibility., Competing Interests: The authors declare no conflict of interest.

Abstract Barrier island lagoons are the most common type of estuary in the world and can be prone to eutrophication as well as the formation and closure of ocean inlets via severe storm activity. This study describes the biological, chemical, and physical changes that occurred along the south shore of Long Island, NY, USA, following the formation of a new ocean inlet in eastern Great South Bay (GSB) by Hurricane Sandy in October of 2012. Time series sampling and experiments were performed at multiple locations within GSB and neighboring Moriches Bay from 2013 through to 2018. Historical comparisons to prior water quality monitoring data, fecal coliform concentrations, and hard clam growth rates were also made. Measurements indicated that the New Inlet provided asymmetrical ocean flushing. Within locations north (Bellport Bay) and east (Narrow Bay, western Moriches Bay) of the New Inlet, water residence times, summer water temperatures, total and dissolved nitrogen, chlorophyll a , the harmful brown tide alga, Aureococcus anophagefferens , pigments associated with diatoms and dinoflagellates (fucoxanthin and peridinin), and fecal coliform bacteria levels all significantly decreased, while salinity, dissolved oxygen, and water clarity significantly increased. In contrast, waters west of the New Inlet within the center of GSB experienced little change in residence times, significant increases in chlorophyll a and harmful brown tides caused by A. anophagefferens , as well as a significant decrease in water clarity and summer dissolved oxygen levels. Growth rates of juvenile hard clams (Mercenaria mercenaria) near the New Inlet increased compared to before the inlet and were significantly higher than in central GSB, where growth rates significantly declined compared to before the inlet. Hence, while enhanced ocean flushing provided a series of key ecosystem benefits for regions near the New Inlet, regions further away (> 10 km) experienced more frequent HABs and poorer performance of bivalves, demonstrating that enhanced ocean flushing provided by the breach was not adequate to fully restore the whole GSB ecosystem. Graphical abstract Image 1 Highlights • In 2012, Hurricane Sandy breached Fire Island and formed the "New Inlet". • The New Inlet has decreased residence time within Great South Bay. • Increased flushing has significantly improved water quality near the New Inlet. • Despite the creation of the New Inlet, central Great South Bay was mostly unaffected. • The New Inlet may improve the growth and performance of bivalves. [ABSTRACT FROM AUTHOR]

Brown tides caused by Aureococcus anophagefferens have occurred annually and severely impacted on the local ecology and economy in the coastal waters of Qinhuangdao, China since 2009. The uptake preference, pigment composition and growth responses of the Chinese strain of A. anophagefferens to different nitrogen substrates were studied in the laboratory to better understand its nitrogen (N) strategies and compare the findings with those from the other strains in the U.S.A. Our results indicated that A. anophagefferens had a high absolute uptake rate (ρ max ) for NH 4 + and low half-saturation constants (K s ) for NO 3 − and urea. It grew faster on the organic substrates (urea and glutamic acid) than that on the inorganic substrates (NO 3 − and NH 4 + ). A. anophagefferens had higher contents of cellular pigments for both photosynthesis (chlorophyll a , chlorophyll c 2 , 19′-butanoyloxyfucoxanthin and fucoxanthin) and photoprotection (β-Carotene and diadinoxanthin) on urea than did on NO 3 − and NH 4 + , suggesting a stronger capability for photosynthesis on urea. A. anophagefferens had higher contents of cellular carbon, N and proteins on urea than did on NO 3 − and NH 4 + , suggesting a stronger capability for the acclimation and storage of C and N on urea. A. anophagefferens produced more β-carotene rather than chlorophyll a on glutamic acid and thus inhibited photosynthesis and carbon fixation. We found in this study that urea was the best N substrate for the growth of A. anophagefferens . A. anophagefferens might have a competitive advantage over other phytoplankton in waters enriched with DON, particularly with urea. [ABSTRACT FROM AUTHOR]

Brown tides of Aureococcus anophagefferens have occurred annually in the coastal waters of Qinhuangdao since 2009. High levels of dissolved organic matter (DOM) are always measured during bloom periods. Study focusing on the effect of DOM on the occurrences of brown tides in this area is scare by far. To analyze the efficiency of DOM hydrolysis by different groups of microorganisms and the possible influence of DOM on the formation of brown tides, extracellular enzymes such as α, β-glucosidases (α, β-GLUs), leucine aminopeptidase (LAP) and alkaline phosphatase (AP) as well as other environmental parameters were analyzed during a pre-bloom period of A. anophagefferens in June 2014. Dissolved organic nitrogen (DON) and phosphorus (DOP) contributed more than half of the total dissolved nutrient pools. Approximately 60–70% of the enzyme activities were associated with phytoplankton of size >5 μm. The hydrolysis rates of LAP were approximately 5 to 20 fold higher than those of AP and α, β-GLUs. The ratios of β-GLU activities: LAP activities indicated the hydrolysis potential related to proteins rather than polysaccharides. The differences in turnover time among the enzymes suggested that DOP was firstly hydrolyzed and recycled in the water in the early minutes, followed by the hydrolysis of DON and dissolved organic carbon (DOC)(in hours). Results suggest that the hydrolysis of DOM, in particular DOP, might significantly contribute to the occurrences of brown tides in the coastal waters of Qinhuangdao, China. [ABSTRACT FROM AUTHOR]

Brown tides caused by the excessive growth of the pelagophyte Aureococcus anophagefferens have occurred frequently in Qinhuangdao, China, since 2009. In this study, the temporal and spatial variations of A. anophagefferens and Minutocellus polymorphus were analyzed using real-time fluorescent quantitative PCR. The relationship between nutrient contents and brown tide events as well as the impacts of the brown tides on the composition of phytoplankton is discussed. The results showed that A. anophagefferens reached peak densities in July. Brown tides occurred in the coastal waters of Funing and Changli, and the main affected areas shifted from south to north throughout the experiment. The A. anophagefferens brown tide event was not monospecific, as M. polymorphus and Prorocentrum minimum were also observed. A redundancy analysis (RDA) indicated that decreasing concentrations of dissolved inorganic nitrogen (DIN) and increasing concentrations of the available organic nitrogen compounds (urea, dissolved free amino acids (DFAA), and dissolved combined amino acids (DCAA)) from March to June may have resulted in the outbreak of the brown bloom of A. anophagefferens, coinciding with a reduction in the community diversity of phytoplankton in the coastal waters of Qinhuangdao. [ABSTRACT FROM AUTHOR]

Many giant dsDNA algal viruses share a common ancestor with Mimivirus -one of the largest viruses' in terms of genetic content. Together' these viruses form the proposed 'Megaviridae' clade of nucleocytoplasmic large DNA viruses. To gauge Megaviridae diversity' we designed degenerate primers targeting the major capsid protein genes of algae-infecting viruses within this group and probed the clade's diversity during the course of a brown tide bloom caused by the harmful pelagophyte' Aureococcus anophagefferens. We amplified target sequences in water samples from two distinct locations (Weesuck Creek and Quantuck Bay' NY) covering 12 weeks concurrent with the proliferation and demise of a bloom. In total' 475 amplicons clustered into 145 operational taxonomic units (OTUs) at 97% identity. One OTU contained 19 sequences with ⩾97% identity to AaV' a member of the Megaviridae clade that infects A. anophagefferens' suggesting AaV was present during the bloom. Unifrac analysis showed clear temporal patterns in algal Megaviridae dynamics' with a shift in the virus community structure that corresponded to the Aureococcus bloom decline in both locations. Our data provide insights regarding the environmental relevance of algal Megaviridae members and raise important questions regarding their phylodynamics across different environmental gradients. [ABSTRACT FROM AUTHOR]

Aureococcus anophagefferens causes economically and ecologically destructive “brown tides” in the United States, China and South Africa. Here we report the 370,920 bp genomic sequence of AaV, a virus capable of infecting and lysing A. anophagefferens . AaV is a member of the nucleocytoplasmic large DNA virus (NCLDV) group, harboring 377 putative coding sequences and 8 tRNAs. Despite being an algal virus, AaV shows no phylogenetic affinity to the Phycodnaviridae family, to which most algae-infecting viruses belong. Core gene phylogenies, shared gene content and genome-wide similarities suggest AaV is the smallest member of the emerging clade “Megaviridae”. The genomic architecture of AaV demonstrates that the ancestral virus had an even smaller genome, which expanded through gene duplication and assimilation of genes from diverse sources including the host itself – some of which probably modulate important host processes. AaV also harbors a number of genes exclusive to phycodnaviruses – reinforcing the hypothesis that Phycodna- and Mimiviridae share a common ancestor. [ABSTRACT FROM AUTHOR]

Abstract: Several field data and experiments show that zooplankton may react to the presence of toxic phytoplankton by reducing its consumption up to the point of starvation. We propose a mathematical system to model this situation using a Monod–Haldane response function. Our results indicate that this mechanism ensures that the toxic phytoplankton does not drive the zooplankton population towards extinction. Also, the insurgence of brown tides is shown numerically under the assumptions underlying this model. [Copyright &y& Elsevier]

Abstract: The detection of brown tide dominated by the pelagophyte Aureococcus anophagefferens in Saldanha Bay in 1997 was the first occurrence of such blooms outside the north-east coast of the USA. Repeated brown tides in a semi-isolated aquaculture facility in the bay have resulted in poor oyster yields during bloom periods threatening the economic viability of the farming venture. The dramatic economic and ecological consequences of brown tides in the USA initiated a considerable research effort for over two decades that has revealed a number of ecophysiological adaptations of Aureococcus proposed to confer an advantage over competing phytoplankton. The aim of the present study was to investigate certain physiological and ecological characteristics of natural brown tide assemblages to provide a comparison with findings from elsewhere. Investigations were conducted on a number of occasions between 1998 and 2003 during visible brown tide events in a semi-isolated oyster culture facility within Saldanha Bay. Microscope counts revealed that Aureococcus was the most abundant phytoplankton species present during these blooms amounting to 96.7% of total phytoplankton and other nanoplankton numbers. Size fractionated experiments confirmed that primary productivity was dominated by the <10μm fraction (87.4%). Nitrogen (N) uptake rates based both on calculations from kinetic parameters and on direct measurements using 15N isotopes show reduced N as NH4 and urea to be far more important than oxidised N as NO3 (f-ratio between 0.04 and 0.24). Organic N as urea provided an important N resource for these brown tides. Uptake affinity estimated from the initial slope of the Michaelis–Menten equation did not reveal any marked preference for either N source; the small contribution from NO3 being dictated largely by low environmental concentrations. There was a marked separation of primary production and N uptake in the vertical such that C/N assimilation ratios ranged from 28.5 at the surface to 1.6 at depth. Depth integrated values more closely approximated the Redfield ratio. Studies investigating the effect of irradiance on primary productivity and N uptake were consistent with a low-light adapted species with light saturation parameters of 71–102μmolm−2 s−1 for photosynthesis and 14–68μmolm−2 s−1 for N uptake. Dark uptake of reduced N was in excess of 50% of maximum rates in the light. The findings of this study support the idea of a species well adapted to growth in turbid waters that are poor in dissolved inorganic nutrients, particularly as NO3, though with significant supplies of organic N. A salient characteristic of Saldanha Bay brown tides was the co-occurrence of a Chrysochromulina sp. that may have exerted some degree of grazing control over Aureococcus. [Copyright &y& Elsevier]