Depth plays a crucial role in shaping marine biodiversity patterns, with species richness typically decreasing with depth. Despite extensive documentation of this pattern, the drivers of richness changes across depth remain unclear. Richness–depth patterns can arise from multiple proximate mechanisms acting simultaneously, such as changes in abundance, evenness, and the spatial aggregations of individuals. Using a unified fram...

Understanding how gene‐flow and selection interact across environmental gradients is essential for assessing population resilience and evaluating the deep‐refugia potential of mesophotic habitats under rapid climate change. In the context of depth, genetic connectivity patterns have been documented for broadcast‐spawning species, but that of brooding marine invertebrates remains largely unexplored, leaving the role of mesophot...

Accumulating data on the increasing degradation of coral reefs worldwide has led to a focus on the unique mesophotic coral ecosystem (MCE) as a potential refuge for threatened shallow-water species (i.e., the deep reef refugia hypothesis: DRRH). Sponges play a crucial role in coral-reef functioning but are often overlooked in benthic surveys. This knowledge gap is especially true for the Red Sea, where data on sponge abundance...

Sponges are animals that feed by filtering water through their perforated body. We examined the in situ diel dynamics of sponge metabolism by continuously measuring the oxygen concentrations in the water inhaled and exhaled by undisturbed sponges. A clear daily pattern of oxygen removal was evident for six of the seven species we studied with their nocturnal oxygen removal being almost double the diurnal values (+ 86 ± 57%). O...

Climate change is predicted to have detrimental impacts on sessile invertebrates, including sponges. Mesophotic ecosystems have been suggested to play a major role as refugia for coral reef sponge species, however knowledge regarding the ability of mesophotic sponges to cope with thermal stress is scarce. In this study we compared the response of the sponge Diacarnus erythraeanus , a widespread Red Sea sponge, from the shallow...

Polychaetes are among the most common marine organisms, and in many habitats they dominate both in species richness and abundance. They are often found in association with other organisms. Specifically, sponges with their complex three-dimensional internal architecture, are known to host a great diversity of polychaetes. Due to the fact that a large number of sponge-associated polychaete species are known to be common on other...

Rich and diverse mesophotic sponge grounds were recently discovered along the easternmost part of the Mediterranean Sea (Israeli coast). Six sites have been surveyed over the last decade (2009-2019) and the sponge specimens discovered and collected in these expeditions have increased the known sponge richness of the Israeli fauna by ~34%. Here we provide an updated checklist along with the distribution of the various species i...

Sponges have long been considered as “living hotels” due to the great diversity and abundance of other taxonomic groups often found in association with them. Sponges are the dominant components of benthic communities in the Levant Sea; and especially in the recently discovered mesophotic sponge grounds off the coast of Israel. However, almost no data exist regarding their associated macrofauna. The current study sought to iden...

Sponges hold a key role in benthic environments, and specifically in the Mediterranean Sea. Past events of mass mortality in sponge communities have been linked to extended periods of high-temperature anomalies, yet it is unknown how a gradual change, such as the constant rise in global seawater temperatures, will affect biodiversity. Here we present a case study of Agelas oroides , a common massive sponge in the Mediterranean...

Determining demosponge reproductive strategies is essential to understanding their ecology and life history, as well as for the management of benthic marine environments. This is especially important in mesophotic ecosystems, which have been suggested to serve as a refuge for shallow-water populations and for which knowledge is lacking. Here we compared the reproductive strategies of two common Mediterranean demosponges specie...

Sponges are a diverse and abundant phylum, globally inhabiting many hard-bottom habitats. However, data on the East-Mediterranean sponge communities are scarce, outdated, and limited to the shallow waters. This study sought to expand the knowledge of the poriferan fauna along the Mediterranean shore of Israel. A newly-discovered mesophotic sponge ground at ~100 m depth was studied using a remotely-operated vehicle (ROV), in ad...

Summary Sponges are benthic filter feeders that play pivotal roles in coupling benthic‐pelagic processes in the oceans that involve transformation of dissolved and particulate organic carbon and nitrogen into biomass. While the contribution of sponge holobionts to the nitrogen cycle has been recognized in past years, their importance in the sulfur cycle, both oceanic and physiological, has only recently gained attention. Spong...

Secondary metabolites protect many marine sponges ( P hylum: P orifera) from settlement by fouling organisms. Previous studies on the subtidal demosponge A xinella verrucosa collected in the W estern M editerranean led to the isolation of compounds that inhibited the settlement of cyprids larvae of the intertidal barnacle B alanus amphitrite , and the enzyme chitinase, which plays a key role in the molting cycle of crustaceans...

Coral reef ecosystems are characterized by high species diversity and intense levels of biotic interaction, particularly competition for space among sessile benthic invertebrates. Using in situ pulse amplitude modulated fluorometry, we demonstrate that secondary metabolites present in the tissues of some Caribbean sponge species have rapid allelopathic effects on the symbiotic algae (zooxanthellae) that live in coral tissues a...