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

Abstract

Abstract. Growth of the inshore sea urchin Psammechinus miliaris (Gmelin) was studied in Loch Creran, western Scotland, using the skeletal growth-marker tetracycline in order to test the validity of natural growth-banding in the coronal test plates as annual age-markers. In order to test whether tetracycline affected the growth of P. miliaris, an injected and a control group of urchins were held in identical conditions in running sea water aquaria for 21 mo from 1989 to 1991 and measured periodically. A small but significant difference in mean size of injected compared to controls was recorded at 12 too, but none during subsequent measurements. Size measurements during the trial were consistent with an annual growth cycle, with a maximum in spring and slowing or cessation of growth during autumn/winter. Tetracyclinelabelled juveniles were recovered up to 18 mo after initial tagging in mark/recapture experiments undertaken from 1987 to 1989 at two intertidal marked quadrats in Loch Creran. Large numbers of P. mitiaris were also marked with tetracycline and held for 1 yr at 10 m depth in seabed cages in Loch Creran during [1988][1989][1990]. All of the intertidal recoveries, and about 69% of the caged specimens that had been successfully labelled, showed a consistent relationship between the position of the tetracycline tag and the pattern of natural growth zones. The remainder were mostly large, slow-growing urchins with the tag positioned near the plate margin. In these the outer growth bands were closely spaced and, particularly if major growth bands seemed to be broken up into double or multiple lines, the major bands were impossible to resolve at the margin. The results support the assumption that in wild populations the dark bands visible with reflected light (translucent in transmitted light) after charring the plate are formed when skeletal growth has stopped or slowed in winter. These lie between wider, lighter coloured (opaque in transmitted light) zones of active plate growth in spring/summer. The dark band formed beyond the tag usually was made up of several closely spaced fine lines, or sometimes of two closely spaced dark bands. The wide growth zones beyond the tag, like those formed previously, usually were broken by fine, dark lines that may represent brief discontinuities in growth. From tagging, the double dark bands can be related to growth over one year; but such anomalous bands, along with the general presence of fine, dark lines interrupting the growth zones, make it difficult reliably to estimate age from the closely spaced peripheral banding on older, slow-growing urchins.

Growth zones and back-calculation for the sea urchin,Sphaerechinus granularis, from the Bay of Brest, France

“…Pearse & Pearse (1975) suggested that natural growth zones should not be used to estimate age without corroborative evidence (ii). The most powerful direct tests of validity were undertaken by several authors by rearing sea urchins tagged with tetracycline in aquaria or cages (Taki, 1972;Ebert, 1988;Gage, 1991Gage, ,1992. Sampling sea-urchins from the field at different seasons (Moore, 1935;Kawamura, 1966;Jensen, 1969;Dix, 1972) showed that the natural growth zones are formed annually.…”

“…Reviews of those studies utilizing growth bands in echinoids have been made by Moore (1935), Jensen (1969), Pearse & Pearse (1975), 1 Smith (1980), Sime (1982), Nichols et al (1985), Comely & Ansell (1988), Ebert (1988) and Gage (1991Gage ( ,1992. Reviews of those studies utilizing growth bands in echinoids have been made by Moore (1935), Jensen (1969), Pearse & Pearse (1975), 1 Smith (1980), Sime (1982), Nichols et al (1985), Comely & Ansell (1988), Ebert (1988) and Gage (1991Gage ( ,1992.…”

Evaluating Age Determination and Spatial Patterns of Growth in Red Sea Urchins in Southeast Alaska

“…Robinson and MacIntyre (1997) documented a positive correlation between test diameter and growth rings found on a part (rotula) of the Aristotle's lantern complex in green sea urchins Strongylocentrotus droebachiensis. Brey et al (1995) documented that growth lines could be accurately used for Antarctic sea urchins Sterechinus neumayeri, while Russell and Meredith (2000) compared tetracycline marking with growth lines on urchin plates and rotulae (see also Gage 1991Gage , 1992. Russell and Meredith (2000) concluded that growth lines on both plates and rotulae were formed annually in some individuals, while more than one band was created in some and less than one complete band was observed in others.…”

Use of plate growth measurement for the estimation of skeletal growth of two sand dollars, Astriclypeus manni (Verrill 1867) and Clypeaster japonicus (D^|^ouml;derlein 1885), in Jeju, Korea

“…Seasonal changes in plate growth often result in alternation of light and dark bands on the plate owing to the differing growth rates between warm and cold seasons (Brykov & Parasyna 1978, Gage 1990, 1991. According to Pearse & Pearse (1975) and Gage (1991), the dark or opaque bands (slow growth) form in winter, while light or translucent bands (fast growth) form in summer when water temperatures are warmer. Consequently, the plate banding patterns have been used in studies of age determination of regular as well as irregular sea urchins (Brykov & Parasyna 1978, Gage 1991, Sano et al 2001).…”

“…According to Pearse & Pearse (1975) and Gage (1991), the dark or opaque bands (slow growth) form in winter, while light or translucent bands (fast growth) form in summer when water temperatures are warmer. Consequently, the plate banding patterns have been used in studies of age determination of regular as well as irregular sea urchins (Brykov & Parasyna 1978, Gage 1991, Sano et al 2001). …”