Premium
Time‐patterns of macrobenthic species in Moreton Bay
Author(s) -
STEPHENSON W.
Publication year - 1980
Publication title -
australian journal of ecology
Language(s) - English
Resource type - Journals
eISSN - 1442-9993
pISSN - 0307-692X
DOI - 10.1111/j.1442-9993.1980.tb01251.x
Subject(s) - bay , range (aeronautics) , sampling (signal processing) , environmental science , abiotic component , ecology , biology , oceanography , physics , geology , detector , optics , composite material , materials science
Data were obtained at 2‐month intervals for ea 31/2 years by quintuplicate sampling with an 0.1 m 2 Smith‐Mclntyre grab at six selected sites in Moreton Bay. A total of 312 species‐in‐sites was obtained; when considering species‐in‐all‐sites this was reduced to 158. Both sets of data were analysed with and without data (species) reduction. After trials of several analytical methods single cyclical regressions involving Fourier transforms were selected as the main method. By prescribing a range of wavelengths, those giving the best and most significant fit to the data were obtained. Two ranges of wavelengths were used, near‐annual and long‐term. The former showed a wide range of optimal periodicities from ca 38 to 60 weeks for one set of data and ca 38 to ca 65 weeks for the other. Species with the more rapid cycles are believed to be under particularly severe control by predator/disturbers. ‘Imposing’ a 52‐week cycle on the data and determining the estimated times of attainment of the first maximum shows a modal distribution with most species attaining maximum populations in September. This agrees with previous, but less intensive work, in Moreton Bay. More species show significant long‐term cycles than show annual cycles, with a spectrum of cycles of from 2 to 7 years (the range scanned), with concentrations at 3, 5 and 6 years. It is impossible to ‘explain’ these varying cycles by any conceivable combination of abiotic factors. Considering cycles of 5, 6 and 7 years, there is convincing evidence in each case that an earlier group of species is replaced, in a synchronous fashion, by a later group. Quite often species disappear from one site and are synchronously replaced at another. It was suspected that the overall situation would be complex, and although this complexity has been partially partitioned and partly clarified, much remains unexplained.