The Biology of Echinocardium cordatum

Abstract

1. Monthly samples of Echinocardium cordatum were taken at Port Erin in 1932,1933 and 1934, and at intervals at Fairlie Sands in the Clyde.2. Growth is continuous throughout the year with the exception of February-March. In their first winter the young urchins attain a length of about 10 mm. at Millport and 15–20 mm. at Port Erin. In their second winter they are about 20 mm. at Millport, and 30–35 mm. at Port Erin.4. The year 1931 was cold and produced a very small brood of young urchins; 1932 and 1933 were warm years and produced very large broods.5. The young settle below low water and migrate into the interval zone after an interval of four to twelve months.6. The gonads of the young urchins mature in their second year. Spawning takes place in June–July–August.7. The nutritive bodies in the ovaries are shown to be derived from the disintegration of relict ova.

Climate effects and benthic–pelagic coupling in the North Sea

“…The abundance of adult Echinocardium cordatum is influenced by temperature (Moore 1936, Beukema 1985 and our analyses also suggest that sea temperature has an important influence on the numbers of E. cordatum larvae in the plankton. Discontinuity analysis indicates that a stepwise change towards a warmer thermal regime occurred in the North Sea after 1987.…”

“…Together with the phenological changes in the North Sea among phytoplankton and grazing holozooplankton that has created a mismatch in the food chain (Edwards & Richardson 2004), changes in phytoplankton in the northern North Sea may help support the increase in abundance of Echinocardium cordatum in this region. Increased larval abundance may improve recruitment (Ólafsson et al 1994, Millar & Emlet 1999 and warmer winters after 1987 may reduce adult mortality (Moore 1936, Beukema 1985. In this way, warmer conditions in the North Sea after 1987, together with increased phytoplankton, may act synergistically to increase the reproductive output, population density and habitat range of Echinocardium cordatum year after year.…”

Skeletal growth zones as age-markers in the sea urchinPsammechinus miliaris

“…This has allowed the age of specimens to be read, as in the trunk of a tree, in estimating size/age relationships and growth rates in individuals of echinoid populations (Deutler 1926, Kume 1929, Moore 1935, 1937, Zoeke 1952, Durham 1955, Moore 1966, Gamble 1967, Jensen 1969a, b, Weber 1969, Pearse et al 1970, Birkeland and Chia 1971, Dix 1972, Taki 1972a, b, Miller and Mann 1973, Sumich and McCauley 1973, Crapp and Willis 1975, Allain 1978, Smith 1980, Walker 1981, Ebert 1982, Sime 1982, Duineveld and Jenness 1984, White et al 1984, Gage and Tyler 1985, Nichols et al 1985, Sime and Cranmer 1985, Gage et al 1986, Gage 1987, Comely and Ansell, 1988. The implied assumption of an annual periodicity in growth of the test is supported from study of size frequencies in sample time-series (Moore 1935, 1936, Lewis 1958, Kawamura 1966, Fuji 1967 and by size measurements of specimens reared in aquaria (Bull 1939, Jensen 1969b, Pearse and Pearse 1975. Further convincing, albeit indirect, evidence for an annual growth periodicity has been obtained by relating the position of t...…”

Differences in growth rates of the sea urchin Echinocardium cordatum as estimated by the parameter w of the von Bertalanffy equation applied to skeletal rings

“…Although Moore (1936) reported that Echinocardium cordatum is essentially a littoral species, more recent studies have shown that the greater portion of the population, at least in the North Sea, is found well offshore, reaching a maximum density at depths of 40 m (Ursin, 1960). The species is ubiquitous throughout the North Sea, but high variations in test lengths and density exist among the various stocks (Ursin, 1960;Buchanan, 1966;van Noort et al, 1979).…”