Unique spicules may confound species differentiation: Taxonomy and biogeography of Melonanchora Carter, 1874 and two new related genera (Myxillidae: Poecilosclerida) from the Okhotsk Sea

Sponges are amongst the most difficult benthic taxa to properly identify, which has led to a prevalence of cryptic species in several sponge genera, especially in those with simple skeletons. This is particularly true for sponges living in remote or hardly accessible environments, such as the deep-sea, as the inaccessibility of their habitat and the lack of accurate descriptions usually leads to misclassifications. However, species can also remain hidden even when they belong to genera that have particularly characteristic features. In these cases, researchers inevitably pay attention to these peculiar features, sometimes disregarding small differences in the other “typical” spicules. The genus Melonanchora Carter, 1874, is among those well suited for a revision, as their representatives possess a unique type of spicule (spherancorae). After a thorough review of the material available for this genus from several institutions, four new species of Melonanchora, M. tumultuosa sp. nov., M. insulsa sp. nov., M. intermedia sp. nov. and M. maeli sp. nov. are formally described from different localities across the Atlanto-Mediterranean region. Additionally, all Melonanchora from the Okhotsk Sea and nearby areas are reassigned to other genera; Melonanchora kobjakovae is transferred to Myxilla (Burtonanchora) while two new genera, Hanstoreia gen. nov. and Arhythmata gen. nov. are created to accommodate Melonanchora globogilva and Melonanchora tetradedritifera, respectively. Hanstoreia gen. nov. is closest to Melonanchora, whereas Arhythmata gen. nov., is closer to Stelodoryx, which is most likely polyphyletic and in need of revision.publishedVersio

Sponge Mass Mortalities in a Warming Mediterranean Sea: Are Cyanobacteria-Harboring Species Worse Off?

Mass mortality events are increasing dramatically in all coastal marine environments. Determining the underlying causes of mass mortality events has proven difficult in the past because of the lack of prior quantitative data on populations and environmental variables. Four-year surveys of two shallow-water sponge species, Ircinia fasciculata and Sarcotragus spinosulum, were carried out in the western Mediterranean Sea. These surveys provided evidence of two severe sponge die-offs (total mortality ranging from 80 to 95% of specimens) occurring in the summers of 2008 and 2009. These events primarily affected I. fasciculata, which hosts both phototrophic and heterotrophic microsymbionts, while they did not affect S. spinosulum, which harbors only heterotrophic bacteria. We observed a significant positive correlation between the percentage of injured I. fasciculata specimens and exposure time to elevated temperature conditions in all populations, suggesting a key role of temperature in triggering mortality events. A comparative ultrastructural study of injured and healthy I. fasciculata specimens showed that cyanobacteria disappeared from injured specimens, which suggests that cyanobacterial decay could be involved in I. fasciculata mortality. A laboratory experiment confirmed that the cyanobacteria harbored by I. fasciculata displayed a significant reduction in photosynthetic efficiency in the highest temperature treatment. The sponge disease reported here led to a severe decrease in the abundance of the surveyed populations. It represents one of the most dramatic mass mortality events to date in the Mediterranean Sea

Spongiaires bathyaux de la mer d’Alboran et du golfe ibéro-marocain

Les peuplements bathyaux d’éponges du détroit de Gibraltar et des regions limitrophes méditerranéenne et atlantique (mer d’Alboran et golfe ibéro-marocain) sont étudiés du point de vue systématique, biogéographique et écologique. Environ 1270 exemplaires ont été récoltés, appartenant à 96 espèces dont 12 sont nouvelles pour la Science, 51 nouvelles pour le golfe ibéro-marocain et 15 nouvelles pour la Méditerranée. L’analyse de la répartition verticale des peuplements révèle trois contingents d’espèces clairement différenciés : l’un formé d’éléments à affinités littorales jusqu’à 250 m, un deuxième constitué d’espèces entre 250 et 1000 m, et un troisième formé par 18 espèces caractéristiques des fonds bathyaux au-delà de 1000 m de profondeur. Aucune corrélation entre les espèces et les masses d’eau méditerranéenne ou atlantique n’a pu être mise en évidence. La mer d’Alboran montre un aspect appauvri de celui du golfe ibéro-marocain.Maurizio Pansini est chercheur auprès de la Faculté des Sciences de l’Université de Gènes (Italie). Maria-Jesus Uriz est chercheur du Consejo Superior de Investigaciones Cientificas, Directeuradjoint du Centro de Estudios Avanzados de Blanes (Espagne) et responsable du Département d’Ecologia Acuatica du même Centre. Nicole Boury-Esnault est chercheur au Centre national de la Recherche scientifique et, après quinze ans passés au Muséum national d’Histoire naturelle, travaille actuellement au Centre d’Océanologie de Marseille, Station marine d’Endoume, URA-41 du CNRS. Les trois auteurs sont des spécialistes reconnus des Spongiaires, travaillant sur la systématique et la biogéographie ainsi que sur la chemotaxonomie, les interactions entre espèces, la biologie, la cytologie et la génétique.</p

Unique spicules may confound species differentiation: Taxonomy and biogeography of Melonanchora Carter, 1874 and two new related genera (Myxillidae: Poecilosclerida) from the Okhotsk Sea

Sponges are amongst the most difficult benthic taxa to properly identify, which has led to a prevalence of cryptic species in several sponge genera, especially in those with simple skeletons. This is particularly true for sponges living in remote or hardly accessible environments, such as the deep-sea, as the inaccessibility of their habitat and the lack of accurate descriptions usually leads to misclassifications. However, species can also remain hidden even when they belong to genera that have particularly characteristic features. In these cases, researchers inevitably pay attention to these peculiar features, sometimes disregarding small differences in the other “typical” spicules. The genus Melonanchora Carter, 1874, is among those well suited for a revision, as their representatives possess a unique type of spicule (spherancorae). After a thorough review of the material available for this genus from several institutions, four new species of Melonanchora, M. tumultuosa sp. nov., M. insulsa sp. nov., M. intermedia sp. nov. and M. maeli sp. nov. are formally described from different localities across the Atlanto-Mediterranean region. Additionally, all Melonanchora from the Okhotsk Sea and nearby areas are reassigned to other genera; Melonanchora kobjakovae is transferred to Myxilla (Burtonanchora) while two new genera, Hanstoreia gen. nov. and Arhythmata gen. nov. are created to accommodate Melonanchora globogilva and Melonanchora tetradedritifera, respectively. Hanstoreia gen. nov. is closest to Melonanchora, whereas Arhythmata gen. nov., is closer to Stelodoryx, which is most likely polyphyletic and in need of revision

Two-way ANOVA results for Cabrera NP <i>Ircinia fasciculata</i> and <i>Sarcotragus spinosulum</i> densities and % of injured specimens, with site (random) and time (fixed) factors.

<p>ANOVA results for Scandola RP <i>Ircinia fasciculata</i> and <i>Sarcotragus spinosulum</i> densities and % of injured specimens across time.</p

Localities and geographical position where the presence (+) or absence (−) of mass mortality was assessed.

*<p>Present study</p>**<p>Maldonado et al. 2010.</p

The effective quantum yield (Φ_PSII) and photosynthetic electron transfer (ETR) during the experiment for the "control,” “medium” and “extreme” treatments.

<p>Bars represent standard errors.</p

Mean percentages of injured <i>Ircinia fasciculata</i> (a) and <i>Sarcotragus spinosulum</i> (b) specimens recorded in Cabrera NP (circles) and Scandola RN (triangles) during the monitoring period.

<p>Bars represent standard errors. Mean concentrations, which were not significantly different in a Tukey test, are joined by horizontal lines.</p

Relationship between the percentage of time above a temperature threshold (26°C) from August 1 to September 30 and the percentage of affected <i>I. fasciculata</i> colonies in Cabrera NP.

<p>Relationship between the percentage of time above a temperature threshold (26°C) from August 1 to September 30 and the percentage of affected <i>I. fasciculata</i> colonies in Cabrera NP.</p

Temperature records (from 1 August to 30 September) at 15 m depth obtained in Scandola RN and Cabrera NP.

<p>TX and T max refer to the average mean and maximum temperatures, respectively, obtained for the available period in each study area.</p