Activity and feeding ofDotilla fenestrata(Brachyura: Ocypodidae) in a warm, temperate South African estuary

Abstract

The activity of and consumption of organic material by the sand-bubbler crab Dotilla fenestrata was studied over neap and spring tides on a sheltered sand bank close to the mouth of the warm, temperate Kowie Estuary, South Africa. Crabs emerged from their burrows only after the tide receded, and it was light. Time to emergence therefore varied from about 30 minutes to three hours after exposure, depending on the time of low water in the early morning vs at midday. General activity of the crab population was longer on a spring tide (about five hours) than on a neap tide (about three hours). Maximum densities of active crabs were 140 m -2 and 41 m -2 on spring and neap tides, respectively. After emergence, crabs spent 60% to 80% of their time feeding. In the Kowie Estuary, D. fenestrata produced between 7 and 12 pseudofaecal pellets, average weight 0.0358 g per pellet, per minute. These pellets had a significantly lower organic and chlorophyll a content than the substratum, and it was estimated that crabs removed about 25% of the organic content from the sediment.

Scratch Traces of Large Ediacara Bilaterian Animals

“…These clusters of pellets appear to be the result of scratch excavation of the matcoated, sandy substrate at or near the focal point of scratch arrays. As such, they partly resemble sand pellets arrayed by a variety of modern tropical, intertidal sand bubbler crabs, including the genera Dotilla and Scopimera (Bulcao and Hodgson, 2012).…”

The effects of near-future coastal acidification on the concentrations of Cd and Pb in the crab Dotilla fenestrata

“…Dotilla fenestrata (Hilgendorf, 1869), the sand-bubbler crab, is a small species and is about 1cm across the carapace (Dray and Paula, 1998;Gherardi et al, 2002;Flores et al, 2005). They belong to the Ocypodidae family of brachyuran crabs and are widely distributed along the East African coast from Kenya to South Africa and also found in Madagascar and The Comoro Islands (Hartnoll, 1973;Bulcao and Hodgson, 2012). They are burrowing decapod crustaceans and occur abundantly on soft sediment shores in tropical and sub-tropical climates (Maitland, 1986;Bulcao and Hodgson, 2012).…”

Osmotic response of Dotilla fenestrata (sand bubbler crab) exposed to combined water acidity and varying metal (Cd and Pb)

“…Dotilla fenestrata (Hilgendorf, 1869), the sand-bubbler crab, is a small species and is about 1cm across the carapace ( Dray and Paula, 1998 ; Gherardi et al., 2002 ; Flores et al., 2005 ). They belong to the Ocypodidae family of brachyuran crabs and are widely distributed along the East African coast from Kenya to South Africa and also found in Madagascar and The Comoro Islands ( Hartnoll, 1973 ; Bulcao and Hodgson, 2012 ). They are burrowing decapod crustaceans and occur abundantly on soft sediment shores in tropical and sub-tropical climates ( Maitland, 1986 ; Bulcao and Hodgson 2012 ).…”

“…They belong to the Ocypodidae family of brachyuran crabs and are widely distributed along the East African coast from Kenya to South Africa and also found in Madagascar and The Comoro Islands (Hartnoll, 1973;Bulcao and Hodgson, 2012). They are burrowing decapod crustaceans and occur abundantly on soft sediment shores in tropical and sub-tropical climates (Maitland, 1986;Bulcao and Hodgson 2012). Sand bubbler crabs are distributed mainly in the north of Durban, South Africa (29 52 0 S; 31 04 0 E), although small numbers are found in warm temperate regions as far south of the Breede River estuary (Day, 1974(Day, , 1981Rius et al, 2010).…”