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Recovery of macrobenthic assemblages following experimental sand burial

100%

Yanez B., Carballo J. L., Olabarria C., Barron J. J.

Oceanologia

2008

tom 50

nr 3

391-420

Periodic inundation by sand is a very common feature of rocky coasts throughout the world. Even so, there have been few direct observations or experiments to investigate the role of sediments on intertidal rocky shores. We designed a field experiment in Mazatl´an Bay, Mexico, to test the initial impact and subsequent recovery of intertidal macrobenthic assemblages exposed to sand burial at two sites of varying wave exposure. Both sites supported different natural assemblages. Treatment plots for the addition of sediment and control plots (50×50 cm), separated by at least 1.5 m, were randomly placed across the mid-water tidal level. The initial response of the resident macrobenthos and the subsequent recolonization was monitored over a period of 95 days. The main effect of sediment deposition at both sites was mortality and removal of biota due to smothering. The recovery process was rapid and may in part have been the result of the mechanism by which the small, disturbed patches were recolonized. Most of the invertebrates colonized the patches as adults; several seaweeds exhibited vegetative growth as the major mechanism of colonization (e.g., Ulva lactuca Linnaeus, 1753, Amphiroa valonioides Yendo, 1902 and Chaetomorpha antennina (Borgensen) Kutzing, 1849). The rate of recovery varied between the sites, however. Recovery of species numbers proceeded quickly at the sheltered site (day 7), but took 95 days at the exposed site. In contrast, biomass reached control levels by day 45 at the sheltered site, but already by day 15 at the exposed site. By day 95, the assemblages recovered to 83.5% and 81% similarity with the controls at the sheltered and exposed sites respectively. Although differences in wave exposure could be very important in determining the different patterns of recovery at both sites, other biological processes may also play an important part.

Individual variation in the over-summering areas of immature Short-toed Snake Eagles Circaetus gallicus

76%

Yanez B., Munoz A.-R., Bildstein K. L., Newton I., Toxopeus A. G., Ferrer M.

Acta Ornithologica

2014

tom 49

nr 1

Satellite tracking is an invaluable tool in the study of bird movements. However, the normally small sample size it involves makes it difficult to obtain data spanning the entire range of migratory behaviour found in particular populations. We recently reported that Spanish immature Short-toed Snake Eagles leave their winter quarters in sub- Saharan Africa to occupy summering areas in northern Africa (north of the Sahara), in contrast to previously reported behaviour of a young French eagle which remained during the summer in the sub-Saharan wintering range. A more recent increase in the sample size of tracked young snake eagles further extends our knowledge of the summering behaviour of this species with one immature reaching the European range but occupying four widely-separated areas during the course of the summer. In the short-term, technology progress may provide the normal use of representative samples to increase accuracy in movement ecology studies.

Ograniczanie wyników

1 Acta Ornithologica

1 Oceanologia

2 Yanez B.

1 Barron J. J.

1 Bildstein K. L.

1 Carballo J. L.

1 Ferrer M.

1 Munoz A.-R.

1 Newton I.

1 Olabarria C.

1 Toxopeus A. G.

1 2014

1 2008

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Recovery of macrobenthic assemblages following experimental sand burial

Individual variation in the over-summering areas of immature Short-toed Snake Eagles Circaetus gallicus