ALBERT

Description: A large-scale database concerning benthic copepods from the Arctic, Baltic Sea, North Sea, British Isles, Adriatic Sea and Crete was compiled to assess species richness, biodiversity, communities, ecological rangesize and biogeographical patterns. The Adriatic showed the highest evenness and the most species-rich communities. Assemblages from the North Sea, British Isles, Baltic and Crete had a lower evenness. The British Isles were characterised by impoverished communities. The ecological specificity of copepod species showed two diverging trends: higher specificity of species in more diverse assemblages was observed in the Adriatic, North Sea and Baltic. A uniformly high species specificity disregarding sample diversity was found on Crete and in the British Isles. Benthic copepod communities showed distinct patterns that clearly fit the predefined geographical regions. Communities were distinguishable and b-diversity was found to be high around Europe, indicating a high species turnover on the scale of this investigation. The British Isles and the North Sea were found to be faunistic links to the Baltic and the Arctic.

Description: Argestidae Por, 1986 are one of the most abundant taxa in the muddy sediments of the deep oceans. This family with up to date 20 genera and 83 described species shows well visible diagnostic characters allowing quick identification at least to family level. In most of the cases, the Argestidae found in deep-sea samples, can be identified down to genus level. Identification to species level is rarely possible, since most of the detected species are new to science. Altogether, the occurrence in each deep-sea sample allover the world combined with the high recognition value, they are supposed to be representative for the biogeographical and chorological distribution of harpacticoid copepods in the deep oceans. The results from the expedition DIVA 1 (M48/1) showed differences between the two sampled stations within the Angola Basin. Preliminary results from DIVA 2 (M63/2), leading to the Cape, Angola and Guinea Basin show that, also comparing these three deep-sea basins, which are separated by ridges, geographic obstacles do not seem to be barriers for benthonic living meiofauna in the South Atlantic. Thus, for harpacticoid copepods, the results from DIVA 2 confirm the conclusion of DIVA 1, that other factors than geographic structures seem to rule the distribution or occurrence of species in the deep of the worlds oceans.

Description: Argestidae POR, 1986 sind überwiegend in der Tiefsee zu finden, wo sie einen Großteil der Copepoda Harpacticoida stellen. Innerhalb der Argestidae lässt sich das Taxon Mesocletodes SARS, 1909 in zwei Gruppen unterscheiden: die Mesocletodes abyssicola-Gruppe, deren Vertreter cuticuläre Fortsätze auf Cephalothorax und Telson tragen, und die Mesocletodes inermis-Gruppe, deren Arten bar derartiger Fortsätze sind. Um diese von BODIN (1968) vorgeschlagene Unterscheidung zu überprüfen, wurde eine auf morphologischen Merkmalen basierende phylogenetische Analyse durchgeführt. Hierzu dienten Tiermaterial der Expedition DIVA 1 im Jahre 2000 ins Angolabecken sowie Literaturdaten. Die Analyse ließ auf die Monophylie der Mesocletodes abyssicola-Gruppe schließen. Demgegenüber lassen jüngst vorgenommene Untersuchungen an zusätzlichem Probenmaterial (z. B. von der Expedition DIVA 2 im Jahre 2005 in das Guineabecken) Zweifel an der Monophylie der Mesocletodes abyssicola-Gruppe aufkommen.

Description: Identification of harpacticoid copepods sampled with a multiple corer during DIVA 1 expedition of RV METEOR (cruise M 48/1) from the Angola Basin yielded the enormous number of 684 species out of 2222 adult specimens. The species number is comparable to that provided by BAGULEY et al. (2006) for the Northern Gulf of Mexico deep-sea (696 species out of 3654 adults). However, BAGULEY et al. (2006) sampled 43 stations scattered over hundreds of kilometres, while we analysed data from only two stations 600 kilometres apart from each other. Regarding the two stations from the Angola Basin, significant diversity differences were detected, the Northern station # 346 being far more diverse than the Southern station # 325 with respect to species density.

Description: Drawing on the example of Argestidae Por, 1986b, community structure and large-scale distribution patterns of harpacticoid copepods at species level were examined in the three southeastern Atlantic deep-sea basins. The study was based on 30 multicorer deployments at depths from 5,035 to 5,655 m during the DIVA-2 expedition. The 1,176 adult and copepodid Argestidae from CIII onwards belong to 114 species. Some species occurred at all five stations; others appeared to be exclusive for single stations. Inclusion of copepodids revealed a higher similarity in species composition among the five stations than consideration of just adults and caused a slight shift toward dominance of single species in the sediments at most locations.

Description: Die Familie der Argestidae Por, 1986 gehört zu den benthonisch lebenden Copepoda Harpacticoida, wird vornehmlich in Probenmaterial aus der Tiefsee gefunden und scheint überdies weltweit verbreitet zu sein. Innerhalb der durch klare Apomorphien charakterisierten Argestidengattung Mesocletodes Sars 1909, der in Tiefseeproben etwa 50% aller Argestidae zufallen, ist die Mesocletodes abyssicola-Gruppe ebenfalls klar gegenüber den übrigen Vertretern dieser Gattung abgegrenzt: kräftige, cuticuläre dorsale Fortsätze auf Cephalothorax und/oder Telson sowie extrem verlängerte Furcaläste werden als Apomorphien für diese Gruppe interpretiert. Zusammen mit ihrer relativ großen Körperlänge (ca. 1mm) und ihrem kompakten, zylindrischen Habitus sind diese Tiere anhand dieser Merkmale eindeutig zu identifizieren und gut in Probenmaterial zu erkennen. Die Mesocletodes abyssicola-Gruppe ist daher und aufgrund ihrer zwar geringen, aber dennoch ausreichend gesammelten Anzahl an Individuen ein ideales Taxon, um die Verbreitung von Tiefsee-Harpacticoida auf Artebene zu untersuchen. Bislang konnte die Art Mesocletodes robustus Por, 1964, von F.D. Por aus einem norwegischen Fjord beschrieben, in den Proben der Expeditionen DIVA (Südostatlantik), ANDEEP (Antarktischer Ozean), NODINAUT (Pazifik) und sogar im östlichen Mittelmeer in nur 180m Tiefe nachgewiesen werden. Gepaart mit Verbreitungsdaten anderer benthonischer Tiefseeorganismen, die jüngst während des „Workshop on Cosmopolitan Deep-Sea Species“ vom 15.-17.12.2008 am DZMB in Wilhelmshaven zusammengetragen wurden, deutet dieser Umstand darauf hin, dass geographische Barrieren wie unterseeische Gebirge oder gar Landmassen, anders als bislang angenommen, die Ausbreitung von Tiefseeorganismen nicht maßgeblich zu beeinträchtigen scheinen.

Description: Argestidae Por, 1986 (Copepoda: Harpacticoida) are one of the most abundant taxa in muddy sediments of the deep oceans. This family with up to date 20 known genera and 83 described species shows well visible morphological characters, allowing quick identification not only at family level, but also at generic and even species level. Altogether, their high abundances, their frequent occurrence in deep-sea samples all over the world, combined with their high recognition value, Argestidae are supposed to be excellent representatives for chorological and biogeographical studies of Harpacticoida the deep oceans. During DIVA 1 expedition of RV METEOR (July/August 2000), two stations at the Angola Basin were sampled quantitatively. As first analyses show, both stations differ remarkably regarding their taxa composition. During DIVA 2 cruise of RV METEOR (February/March 2005), the Cape Basin, Angola Basin, and Guinea Basin were sampled. First results indicate that both Cape and Guinea Basin show considerable similarity considering species occurrence but differ remarkably from the Angola Basin. Since the Angola Basin is geographically positioned between the Cape and Guinea Basin, the obtained results indicate, that other factors than geographic structures seem to rule the occurrence of benthonic living harpacticoid copepods in the deep oceans.

Description: The harpacticoid families Ancorabolidae Sars, 1909 and Argestidae Por, 1986, are both regarded as representatives for deep-sea meiofauna, either being worldwide distributed with predominant occurrence in deep-sea habitats. In contrast to Ancorabolidae, Argestidae include more described species, show higher frequency and higher individual numbers in deep-sea samples. The body of Argestidae is of compact, cylindrical shape whereas the body of Ancorabolidae appears to be more delicate through conspicuous processes on all body somites, indicating different life styles and needs to the habitat in the two families. Anyhow, due to clear morphological features in the two families and possibly different preferences, Ancorabolidae and Argestidae are both excellent groups for biogeographical studies on species level. To date, predominantly data from the Atlantic region are available. Thus, the actual distribution might be misrepresented by the generic and the specific distribution focused on the Atlantic ocean including the southern ocean. One single record of Ceratonotus steiningeri George, 2006 in the south Atlantic as well as in the Pacific ocean leads to the assumption, that there indeed is a species distribution exceeding only Atlantic dispersal. This is supported by five additional records on generic level of argestid and ancorabolid specimens from the Atlantic, the Southern, the Indian, and the Pacific ocean.

Description: Belonging to the Argestidae Por, 1986, the genus Mesocletodes Sars, 1909 is known as a typical, but not exclusive deep-sea taxon. Within this genus, species belonging to the Mesocletodes abyssicolagroup have dorsal cuticular processes at the cephalothorax and/or the last abdominal somite and extremely elongated furcal rami. Up to date, 9 species of this group are described. During the expedition Diva 1 of RV #8220; Meteor #8221; in August 2000 to the Angola Basin, 20 specimens of the Mesocletodes abyssicola- group were sampled. Distributed to 11 species, all 20 specimens are new to science. The aim of this project was to elucidate the phylogenetic status of the Mesocletodes abyssicola-group. Altogether 14 species (included 5 new described species from the Angola Basin) of the Mesocletodes abyssicola- group were used for a phylogenetic analysis based on morphological characters.