Tim Wyatt

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UNESCO Harmful Algae News NO.34

Zenodo (CERN European Organization for Nuclear Research), Jan 23, 2023

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Deterministic signals in Scottish and Irish herring (Clupea harengus) catches

Scientia Marina, 1995

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Deterministic signals in European fish catches, wine harvests, and sea-level, and further experiments

International Journal of Climatology, Sep 1, 1993

Maximum entropy spectrum analysis of six fish catch series, seven series giving dates of wine har... more Maximum entropy spectrum analysis of six fish catch series, seven series giving dates of wine harvest, and forty four height of sea-level records from Europe yields evidence for two peaks with periods 18-19 and 10-11 years, the same terms recently reported in European tree-ring chronologies. For each series the two wavetrains are obtained by bandpass filters, summed, superimposed on the trend-like components of the raw data, and plotted against the raw data. The contribution, on average, of the waves to total variance in the raw data varies from a high of 50 per cent for fish catches to a low of 14 per cent for dates of wine harvest (the mean contribution for height of sea-level is 18 per cent). The peaks are identified as the 18.6-year luni-solar, M,, and 10-1 1-year solar cycle, S,, signals, which also have been reported recently in other climate variables, such as air temperature, air pressure, in rain-gauge and tree-ring data from North and South America, South Africa, Tasmania, and New Zealand; and in sea-surface temperature as well as in American crop yield and other economic data. Further experiments show that with 110 years, or more, of data the Yule-Walker method of spectrum analysis has sufficient resolution to resolve both signals. It is also shown that failure to apply a properly designed digital high-pass filter to climate records prior to spectrum analysis usually leads to failure in detecting the terms.

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The growth season in the sea

Journal of Plankton Research, 1980

UNESCO Harmful Algae News NO.19

Zenodo (CERN European Organization for Nuclear Research), Oct 13, 1999

Table 1.-Species of phytoplankton infected experimentally with the "diablillo parasite". C, cultu... more

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UNESCO Harmful Algae News NO.35

Zenodo (CERN European Organization for Nuclear Research), Nov 27, 2007

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Long term changes in marine fish populations : a symposium in Vigo. España. 18-21 Nov. 1986 = Cambios de largo termino en poblaciones de peces marinos : un simposio en Vigo. España. 18-21 Nov. 1986

Application of a model to an estuarine ecosystem

Limnology and Oceanography, Mar 1, 1973

should be carried through the calculations so that the final estimates of production will appear ... more should be carried through the calculations so that the final estimates of production will appear as a range of values rather than as a single value (see Table 2). The ranges of the mortality coefficients, and of the values derived from them, are not confidence limits. Rather, they are the limiting values of the coefficients that would be consistent with the observed relative abundances. Confidence limits can only be determined if replicate samples are available and if the assumption is made that each stage has a constant characteristic mortality within the period and area represented by the set of samples. The ranges given for the estimates of "equal mortality" in Table 1 indicate broad confidence limits for many stages. Some of the variability is certainly due to sampling error. However, calculations with the numbers in one class halved and those in the adjacent class doubled, and the reverse for the two classes, produced ranges appreciably smaller than those given in Table 1, suggesting that violation of the assumption that each pair of stages had a single constant mortality rate over a period of 4 months was probably also contributing to the large ranges observed. As stated at the outset, there is no satisfactory way of obtaining a single estimate for a mortality coefficient unless the initial Application of a model to an estuarine ecosystem ABSTRACT The annual cycles of primary production and plankton succession in the Cochin Backwater, South India, are examined in the context of a model given by Margalef. The increased flushing of the estuary caused by the southwest monsoon is seen as the main driving force behind the changes which take place. Fish production in the estuary is high when compared with primary production; it is suggested that detritus is an important component of the food web.

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The interaction of lunar and solar time in relation to fish abundance

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Ekman transport and sardine yields in Western Iberia

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Further Remarks on Red Tide Models

Environmental Letters, 1975

Vertical migration as an accumulation mechanism in the formation of red tide models is discussed ... more Vertical migration as an accumulation mechanism in the formation of red tide models is discussed with reference to extant mathematical models. Its relationship to other biological and physical factors such as population density changes, tidal rhythms, nutrient limitation and light intensity is evaluated in terms of its possible causal role in red tides.

Racial Differences in Irish Sea and North Sea Plaice (Pleuronectes platessa)

Nature, May 1, 1969

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Red tides and algal strategies

Springer eBooks, 1974

Several models have emphasized the importance of turbulence in relation to the dynamics of plankt... more Several models have emphasized the importance of turbulence in relation to the dynamics of plankton distribution. Two very simple but instructive examples are those of Kierstead and Slobodkin (1953) in which the size of a plankton patch is determined by the magnitude of the turbulent diffusion, and of Margalef (1967) in which the flushing rate of an estuary plays a similar role. In both these models the potential increase in plankton populations through their reproductive activities is offset by turbulence or advection, and the latter processes effectively determine the minimum reproductive rates of the populations if they are to remain in existence. Margalef’s model has been used to interpret data from an Indian estuary in which there is a marked seasonal change in flushing rate as a result of the southwest monsoon (Wyatt and Qasim, 1973). This study suggested that increased reproductive effort is not the only possible response to the problem posed by the model, and that other strategies can be adopted to circumvent the losses consequent on turbulent processes. In the model presented here, loss of reproductive effort through turbulence is again central, though not made explicit in the mathematical formulation.

UNESCO Harmful Algae News NO.24

Zenodo (CERN European Organization for Nuclear Research), Oct 12, 2003

Microscopic analysis, over 70 years ago, of the stomach contents of the Lesser Flamingo, Phoenico... more Microscopic analysis, over 70 years ago, of the stomach contents of the Lesser Flamingo, Phoeniconaias minor, confirmed what is apparent from the birds' ecology, feeding habits and bill structure: they feed on cyanobacteria [1]. The massive populations, at times over a million, of Lesser Flamingo at Kenya's Rift Valley saline, alkaline lakes, receive nutrients and energy from the local blooms of cyanobacteria, mainly Arthrospira spp. (formerly termed Spirulina). Although flamingos also feed on diatoms and invertebrates, e.g. brine shrimp, it is thought that the cyanobacteria can serve as the sole food of P. minor. Over the past decade, episodic mass mortalities of Lesser Flamingos have occurred at the lakes [2]. The locations involved, including Lakes Nakuru, Bogoria

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UNESCO Harmful Algae News NO.20

Zenodo (CERN European Organization for Nuclear Research), May 15, 2000

The publication of Harmful Algae News is sponsored by the Botanical Institute, University of Cope... more

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UNESCO Harmful Algae News NO.9

Zenodo (CERN European Organization for Nuclear Research), Nov 27, 1994

An investigation into the agent responsible for food poisoning events associated with eating seaf... more An investigation into the agent responsible for food poisoning events associated with eating seafood has led to the incrimination of molluscs collected on the Mediterranean shoreline of Morocco. Their gathering and sale are now banned. The study was carried out on two species currently consumed in the region: the cockle, Cardium tuberculatum , and the hard-shell clam, Cuterce chrome. These species were sampled at regular intervals over a year, from May 1993 to May 1994, in the region of Tetouan at Kaa Stras and Oued Laou, in order to assess the toxicity of the bivalves there. Extracts of the molluscs were prepared according to the official method (Association of Official and Analytical Chemists, 1980). The toxicity of the extracts was assayed on Swiss Albjno mice, Cardium tuberculatum gave the highest toxicities at Kaa Stras, but in both cases toxicity levels remained high throughout the year and produced rapid death, preceded by PSP-type symptoms, while Cuterce chrome gave lower levels, whatever the period of collection. Cardium tuberculatum: Kaa Stras, toxicity 1207 Mouse Units (MU)/100g of meat. Oued Laou, 773 MU/100g Cuterce chrome: 190 MUI100g Comparative investigation of the toxicity in different organs of the cockles showed that toxicity levels were clearly higher in the foot (5580 MU/100g) than in the mantle (1030 MIUl100g). The investigation carried out has shown that biotoxin presence is permanent in cockles in the region of Tetouan, but varies over the year.

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UNESCO Harmful Algae News NO.8

Zenodo (CERN European Organization for Nuclear Research), Jun 27, 1994

This event assembled 273 registered participants and some occasional visitors, in all about 300 p... more This event assembled 273 registered participants and some occasional visitors, in all about 300 persons from more than 40 countries, during five days of plenary sessions and round table discussions. Four scientific themes were explored: the mechanisms of harmful bloom formation, identification and dete&"on of responsible species, cellular biochemistry and physiology, and bioaccumulation effects of phycotoxins. These themes were treated in oral communications and 160 posters, while round table discussions were devoted to subjects previously given less consideration, such as toxic Cyanobacteria blooms and the ecology of benthic dinoflagellates.

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UNESCO Harmful Algae News NO.28

Zenodo (CERN European Organization for Nuclear Research), Aug 15, 2005

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UNESCO Harmful Algae News NO.27

Zenodo (CERN European Organization for Nuclear Research), Dec 8, 2004

The Intergovernmental Oceanographic Commission of UNESCO HARMFUL ALGAE NEWS An IOC Newsletter on ... more The Intergovernmental Oceanographic Commission of UNESCO HARMFUL ALGAE NEWS An IOC Newsletter on toxic algae and algal blooms No. 27 December 2004 http://ioc.unesco.org/hab/news.htm (Cont'd on p. 2) Cape Agulhas marks the geographical boundary between Indian and Atlantic Oceans, but the dynamic boundary where the Agulhas and Benguela Currents meet fluctuates, and usually lies nearer Cape Point where the Agulhas casts eddies into the Atlantic. Here Asian (A. tamiyavanichi) and American (A. catenella) clades of Alexandrium meet (Carlos Ruiz Sebastián). One of them may have been responsible for the deaths of half a million fur seals on Possession Island in the early 19th century [1]. This conjunction of members of different clades centred on distant waters leads to the question of whether there are genuinely cosmopolitan species. Karenia brevis was briefly regarded as cosmopolitan, but improved taxonomic knowledge has shown that it is not, and now we have several newly described ones to contend with (Miguel de Salas). Grethe Hasle recently reviewed the cosmopolitanism of Pseudo-nitzschia [2], and it is clear from her discussion that the concept is as much operational as biological. Morphologically 'difficult' species are more cosmopolitan than others [3], but sexual compatibility and genetic studies of P. pungens appear to support a cosmopolitan interpretation (Griet Casteleyn). If true cosmopolitanism (in Ekman's [4] sense) should eventually be rejected ('we are still far from a reliable assessment of taxonomic units that are phylogenetically significant [5]), yet genetic homogeneity of some widespread species convincingly demonstrated, then anthropogenic spreading by vectors like ballast water would be even more strongly indicated [6]. Studies of intra-and interspecific Cape Agulhas Ehrenberg's sketches (from sheet 957) of «Peridinium splendor-maris», courtesy the Ehrenberg Collection, Museum für Naturkunde, Berlin. The entire collection of drawings is online an available free for non-commercial uses at: http://www.museum.hu-berlin.de:55080/Ehrenberg/.

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UNESCO Harmful Algae News NO.29

Zenodo (CERN European Organization for Nuclear Research), Dec 15, 2005

Cont'd on p.2) (Cont'd on p. 3) Alexandrium monilatum (Howell) Balech bloom in the Gulf of Nicoya... more Cont'd on p.2) (Cont'd on p. 3) Alexandrium monilatum (Howell) Balech bloom in the Gulf of Nicoya, Puntarenas The Gulf of Nicoya, an estuary on the pacific coast of Costa Rica, extends 80 Km, from the Tempisque River to the Pacific, with a maximum width of 50 Km at the mouth, and an area of 1550 Km 2. Hydrography of the Gulf depends on rainfall and wind patterns. Nutrient advection into the Gulf, during the rainy season (May to November) carried by the Grande de Tárcoles and Tempisque Rivers [1], have a stimulant effect on phytoplankton abundance [1-3] and composition [4]. The Gulf of Nicoya is a very important fishing ground on the Pacific coast. About 800 families make their living from shellfish extraction in the Gulf. The Gulf waters and the surrounding mangroves are also important nursery areas for larvae and juveniles of commercially

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