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Interannual variation of growth and recruitment in Pontoporeia affinis (Lindström) (Crustacea: Amphipoda) in relation to abundance fluctuations

1986; Elsevier BV; Volume: 101; Issue: 1-2 Linguagem: Inglês

10.1016/0022-0981(86)90041-9

1879-1697

Jouko Sarvala,

Marine and coastal plant biology

Marked and regular changes in growth and recruitment were found to accompany abundance fluctuations of the amphipod Pontoporeia affinis (Lindström) in a northern Baltic coastal area. Seasonal series of quantitative macrobenthos samples were collected in 1967–1970 from different depths and archipelago zones near Tvärminne Zoological Station, southwestern Finland. Strong interannual fluctuations in the abundance of P. affinis, consistent with earlier long-term studies in the area, were observed at a 34-m soft-bottom site: the numbers declined from 1967 to a minimum of 1800 ind. · m−2 in 1968, and then increased to a maximum of 27600 ind. · m−2 in 1970. During the decline, relative length growth rates were low and population mortalities high, while the maximum growth rate accompanied by low mortality coincided with the population minimum in 1968. Differences in recruitment were even more pronounced. Although the age group due to reproduce was only 1.4 times more abundant in autumn 1969 than in autumn 1967, the population of young released by these animals in spring 1970 was 10.8 times that released in spring 1968; recruitment in spring 1970 was close to the maximum possible. These variations of recruitment were not correlated with temperature or primary production. A model is proposed for the regulation of P. affinis abundance. At high abundance levels, intraspecific competition for food may lead to overgrazing of the microbial food and sediment organic matter. The ensuing impaired growth and reproduction in turn lead to low numbers, which again allows recovery of the food source, good growth and successful reproduction. Thus, density-dependent success of recruitment may cause the cyclic changes of P. affinis abundance.