Predation impacts by the dominant soft bodied and durophagous predators on temperate intertidal shores
Data files
May 23, 2024 version files 621.58 KB
Abstract
Substantial research exists on predation and its ecology. Most research has focused on durophagous fish, brachyuran crabs, and lobsters. Data are lacking, however, on soft bodied predators like anemones, and their contribution to overall levels of predation remains largely unevaluated. Here we compared predation rates of the durophagous predator, the crab Carcinus maenas and the soft bodied predator, the anemone Actinia equina on 15 intertidal shores around Anglesey, north Wales. We employed a novel approach to assess predation based on measuring faecal output from recently collected individuals and converting to food consumed using absorption efficiencies measured using potential prey species inhabiting the same shores. Anemone mean abundance was 8.21 (±0.27, s.e.), whereas for C. maenas it was 0.23± 0.02. Absorption efficiencies when fed mussel tissue, a polychaete worm, or a shrimp were 92.8%-94.0% in C. Maenas and 40.5%-95.8% in A. equina. This reflected the different feeding modes of the two predators. Unexpectedly A. equina consumed 3.5-7 times more prey than C. maenas. The consumption of larger amounts of prey by an anemone than the dominant durophagous predator has important consequences for calculating energy flows in food webs, understanding predation controls in assemblages, and potentially for wider predation trends
README: Predation impacts by the dominant soft bodied and durophagous predators on temperate intertidal shores
The file entitled "Raw data - predator abundance and size" gives data on surveys of numbers of anemone and crab predators on 15 beaches around the Isle of Anglesey between 22 June and 10 July 2021. It details the name of the bay, shore type, exposure rating (following the method of Lewis (1964)), the number of the transect taken at the site, the transect length, the distance between quadrats along the transect, the number of the quadrat, whether the substratum was underwater (“wet”, typically a pool), or above water and hence “dry”, and both the numbers of crabs or anemones present, with their sizes, in any given quadrat.
The file entitled "Raw data - faecal egestion - final" provides data on amounts of faeces produced by recently collected individuals. It gives the number of the aluminium boat that was used to process faeces, the boat weight (g), the weight of the boat plus wet faeces (g), and the dry weight and ash weight of faeces plus the boat (g). Ash-free dry weight values (g) were calculated as the difference between dry and ash weights, and are presented as amounts produced by each individual for a period of 7 days after collection. It also gives values for the size of each individual studied in terms of Wet, dry, ash, and ash-free dry weights, using the same methods and terminology as those for faecal production.