­Reproductive strategies of two common sympatric Mediterranean sponges:Dysidea avara(Dictyoceratida) andPhorbas tenacior(Poecilosclerida)

Abstract

Despite their abundance in benthic ecosystems, life cycles and reproductive features of most sponge species remain unknown. We have studied the main reproductive features of two demosponges, Dysidea avara and Phorbas tenacior, belonging to phylogenetically distant groups: Orders Dictyoceratida and Poecilosclerida, respectively. Both sponges are abundant and share habitat in the Mediterranean rocky sublittoral. They brood parenchymella larvae with different morphology and behaviour. Sampling was conducted monthly over a two-year period in a locality where both species coexist. The two species reproduced in spring-summer, and presented species-specific reproductive features despite being subject to the same environmental conditions. D. avara has a shorter reproductive period than P. tenacior, ending before the peak of temperature in summer, while the reproductive period of P. tenacior lasts until beginning of autumn. Brooding larvae were present in June-July in D. avara, and in August-October in P. tenacior. Larval size, reproductive effort and number of larvae produced (measured the month with the maximum production) were significantly higher in D. avara than in P. tenacior. A higher reproductive effort and larval traits point to a more opportunistic life strategy in D. avara than in P. tenacior. A lack of overlap in the timing of larval release, as well as different reproductive traits, may reduce competition and facilitate the coexistence of these two sympatric and abundant sponges.

Reproductive Biology of Geodia Species (Porifera, Tetractinellida) From Boreo-Arctic North-Atlantic Deep-Sea Sponge Grounds

“…For instance, individuals of G. barretti with mature female gametes and those of G. atlantica with premature female gametes were found at the same location and year, e.g., in Rosemary Bank Seamount in September 2016. This phenomenon has also been observed in Mediterranean species sharing the same habitat, which have to cope with the same nutrient regimes, staggering in time their resource allocation (Riesgo and Maldonado, 2008;Pérez-Porro et al, 2012;De Caralt et al, 2018). The different timing in gametogenesis and spawning among species could also be a strategy for avoiding cross-fertilization between different species and therefore hybridization.…”

Size Is the Major Determinant of Pumping Rates in Marine Sponges

“…The reproductive investment and spawning in most Mediterranean sponges occur between spring and fall (Coma et al, 2000;Mariani et al, 2005). C. reniformis, D. avara, and C. crambe reproduce from June to August (Mariani et al, 2005;Riesgo and Maldonado, 2008;de Caralt et al, 2018), A. oroides reproduces from June to July (Liaci and Sciscioli, 1975), and the onset of oogenesis in P. ficiformis has been observed in May although spawning occurs in late autumn-early winter (November-December, Maldonado and Riesgo, 2009). Unfortunately, we did not collect histological samples in this study.…”

Enjoying the warming Mediterranean: Transcriptomic responses to temperature changes of a thermophilous keystone species in benthic communities

“…7° and 22°C marked the lower and upper thresholds, respectively, at which all individuals used for the trials remained alive, visually healthy (intact skin, no algae or microorganism colonies growing up over the animal surface and no massive spine lost) and active (feet and spines movement). For the cold treatment, 7°C (a decrease of 6°C relative to the control) was the limit temperature achievable in winter in shallow embayments in the NW Mediterranean (e.g., Ordóñez et al, 2015), while for the warm treatment we increased temperature by 9°C (relative to the control), being 22°-23°C the conditions encountered in mid-summer in the study area (e.g., De Caralt, González, Turon, & Uriz, 2018;Marbà et al, 2015;Pastor, 2012). Over 22°C, experimental animals either died or presented clear signs of infection with microorganism colonies over the skin and/or massive loss of spines.…”