Patterns of resource allocation to somatic, defensive, and reproductive functions in the Mediterranean encrusting sponge Crambe crambe (Demospongiae, Poecilosclerida)

Abstract

The pattern of resource allocation in the sponge Crambe crambe (Schmidt) (Demospongiae, Poecilosclerida) in 2 contrasting habitats and in specimens of 3 size classes was studied. The sponge biomass per unit area increased with sponge size in both illuminated and dark environments. An increase with size was also found in the illuminated habitat for the investment in organic matter per unit area This parameter was almost constant among the 3 size classes from the shaded habitat, with values similar to those of the medium-slzed specimens from the lllum~nated environment The amount of sihca per mm2 was higher in the dark site where it proved size-dependent, whereas ~t dld not vary with size in the illuminated habitat Investment in reproduction per unit area was higher in the illuminated wall and was positively correlated with size in both habitats. The amount of calcareous debris included by the sponge during its growth did not vary across size classes in either habitat. All variables related to sponge thickness showed significant differences between the 2 sites studied, while neither the size nor the interaction of habitat and size significantly influenced their values. The specimens were thicker in the illuminated habitat, both in their choanosome and ectosome layers. No variations with size or site were found for the canal system. There was a significant habitat effect on the amount of matrix, which was higher in the illuminated environment. Sponges produced more collagen in the shaded environment than in the illuminated site. This was particularly true for specimens larger than 1000 mm2 (medium and large size classes). As for the number of fibres, there was also significantly more fibre material in the sciaphilous sponges. A significant Interaction was found between habitat and size effects on the number of cells per sponge section. The pattern of resource allocation to the different functions considered was similar in medium-sized specimens from the 2 contrasting habitats except for the number of cells and amount of collagen per sponge section. Small and large sponges, on the other hand, featured the highest between-habitat differences in resource allocation. Large sponges from the illuminated habitat invested relatively more energy in organic matter and less in mineral and collagen structures than their sciaphilous counterparts. Small photophilic sponges invested more in silica than small sciaphilous specimens. Investment in reproduction was notably hlgher In the whole size range of photophilic sponges than in the corresponding size classes from the dark site. Consequently, thls species seems able to shift its resource allocation as a function of size and environmental conditions. We propose an interpretation in terms of a higher competitive pressure in the shaded environment that results in increased investment in defensive/supportive (mineral and organic) structures and a lower investment in somatic growth (organic matter) and reproductive output (larvae).

Decadal demographic trends of a long-lived temperate encrusting sponge

“…The number of genets varied little over time (annual mean change: 3.6 ± 0.76 genets), their survival was high and recruitment via larvae was very low (mean: 0.9 ± 0.26 recruits yr -1 ). We did not detect mortality of large specimens despite their comparatively small size in relation to those encountered in the field and previously reported (Uriz et al 1995. Overall, this population is mainly characterized by the inputs (fission) and outputs (fusion and partial mortality) of asexual ramets.…”

“…This pattern of relative constancy may result from the generally low dynamics of this species, where low mortality is accompanied by low growth and/or infrequent or unsuccessful recruitment events. This lack of recruitment is not due to the failure of larvae production, as specimens with a size range of 1 to 1000 mm 2 include larvae (Uriz et al 1995), but rather the low survival of juveniles , De Caralt et al 2007. During the 14 yr study period, only 10% (14/132) of newly recruited sponges resulted from sexually produced larvae and survived successfully.…”

Chemical mediation of interactions among marine organisms

“…226 The deterrent properties of two Mediterranean sponges, Crambe crambe and Dysidea avara, were studied at three stages of their life cycles, larvae, recruits and adults. 227 Crambe crambe was effectively defended as an adult from grazing by the sea urchin Paracentrotus lividus, but larvae and young recruits were readily eaten by the fish Parablennius incognitus. In contrast, Dysidea avara larvae and recruits were avoided by the fish but adult tissues and extracts were readily eaten by the sea urchin.…”

Antibiotic, cytotoxic and enzyme inhibitory activity of crude extracts from Brazilian marine invertebrates

“…Marine sponges, ascidians, soft-bodied cnidaria and bryozoans are representative groups of marine invertebrates which are chemically defended against predators (for selected examples, see Aceret et al, 2001;Becerro et al, 1998;Burns et al, 2003;Chanas et al, 1996;Epifanio et al, 1999a;Epifanio et al, 1999b;Kubanek et al, 2002;Lindel et al, 2000;Lindquist, 1996;Marin et al, 1998;McClintock and Baker, 1997;O'Neal and Pawlik, 2002;Pawlik et al, 1995;Pisut and Pawlik, 2002;Stachowicz and Lindquist, 1997;Van Alstyne et al, 1994;Vervoort et al, 1998;Waddell and Pawlik, 2000), fouling (Becerro et al, 1997;Bhosale et al, 2002;Hattori et al, 2001;Henrikson and Pawlik, 1995;Kelly et al, 2003;Wahl et al, 1994), larval settlement (reviewed in Davis et al, 1989;Fusetani, 1997;Martín and Uriz, 1993;Pawlik, 1992) and solar UV radiation (Bandaranayake et al, 1996;Dionisio-Sese et al, 1997;Dunlap et al, 1986;Stachowicz and Lindquist, 1997). The chemical defenses of sessile marine invertebrates may not only possess a specifi c ecological or physiological role, but may also exert a multitude of biological activities, as it has been demonstrated for the Mediterranean sponge Crambe crambe (Becerro et al, 1994;Uriz et al, 1995;Turon et al, 1996;Uri...…”