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We documented the current status of the macrobenthic community of Lake Nojiri (surface area: 4.56 km2; maximum depth: 38.5 m; altitude: 654 m above sea level; mesotrophic lake), and examined changes over time in the densities of chironomids and oligochaetes, by comparison with previous quantitative data of the lake reported in 1931 and 1973. We discussed the succession of benthic macroinvertebrates in relation to changes in the lake bottom environment, as evidence of lake eutrophication. On March 10, 2015, a bathymetrical sampling survey was carried out using a standard Ekman grab at each of the 5 stations (min. ca. 6 m – max. ca. 27 m) in Lake Nojiri. The average densities of the benthic communities for all the stations were ca. 5000m-2, comprised principally of oligochaetes ca. 2800 m-2 (57%) and chironomids ca. 2100 m-2 (43%), whereas their benthic biomass averaged ca. 9.7 g m-2, chironomids ca. 7.6 g m-2 (77%) and oligochaetes ca. 2.3 g m-2 (23%). In the shallower stations, the dominant species was Heterotrissocladius sp., but Chironomus nipponensis Tokunaga was the dominant species in the deeper stations. The densities of C. nipponensis was ca. 14 times higher than those reported by Miyadi in 1931 and 4 times higher than reported by Kitagawa in 1973a. In recent years the density of the oligochaete Tubifex tubifex, has tended to increase and the anoxic- and anaerobic-layer have thickened, especially in deeper regions where they are widely distributed. Moreover, we found differences in the C. nipponensis larval growth rate with water depth, i.e., small IV-instar larvae that dominated at the deepest Station 5. At this station, we suggest that low dissolved oxygen concentration and low water temperature during summer-fall suppresses growth of C. nipponensis. Large environmental changes must have affected chironomid and oligochaete densities and growth rate of C. nipponensis, especially in the deeper regions with low dissolved oxygen concentrations, low water temperature and high organic matter (ignition loss; 15.0% in St. 4 and 13.9% in St. 5) in the sediments. This is a strong evidence that the eutrophication of this lake is continuing., Article, JOURNAL OF LIMNOLOGY.77(1):81-87(2018)

西湖湖底に生息するミズムシ類の水平分布と生息密度、現存量などを明らかにし、過去のデータと比較することにより、湖底環境の変化を推測することを目的として、2009年3月に湖全域にわたる水平分布調査を行った。全18調査地点のうち、Asellus (s. str.) hilgendorfi Bovallius が捕獲されたのは7地点で、最大1170±1054匹/㎡ (St.7；水深29.6m) であった。捕獲された地点のうち、最も水深の深い地点は58.0m (St.10；119±68匹/㎡) で、浅い地点は29.6mであった。密度の高い地域は湖中央部の北岸に集中していた。Miyadi (1932) の報告と比較すると、A. hilgendorfi の水深分布が近年、水深60m 以深では分布しなくなったこと、分布域が狭くなっていること、最大個体数密度も浅いほうにシフトしていること、などが明らかとなり、60m 以深の湖底環境に変化が生じていることが示唆された。, Article, 環動昆.21(4):231-237(2010)

Gorgonians are important components of coastal ecosystems, as they provide niches, natural compounds with medical applications and are used as bioindicators. Species composition and assemblage structure of gorgonians (Anthozoa: Octocorallia) were studied along a bathymetric profile in the Southern Mexican Pacific coast. Species composition was based on specimens collected within a depth range of 0-70m in 15 sites. The relative abundance of species was determined in six sites at four depths (5, 10, 20 and 25m) using three 10m2 transects at each depth level. Twenty-seven species of gorgonians belonging to six genera and three families were registered. The species composition varied with depth: 11 species were distributed between 0-25m depth, while 17 species were found between 40-70m depth interval. The shallow zone is characterized by a relatively large abundance of gorgonians, dominated by colonies of Leptogorgia cuspidata and L. ena. In contrast, the deepest zone was characterized by relatively low abundance of gorgonians, dominated by L. alba, the only species observed in both depth intervals. The similarity analysis showed differences in the composition and abundance of species by depth and site, suggesting that the main factor in determining the assemblage structure is depth. Results of this study suggest that the highest richness of gorgonian species in the study area may be located at depths of 40-70m, whereas the highest abundances are found between 5 and 10m depth. This study represents a contribution to the poorly known eastern Pacific gorgonian biota. La composición de especies y estructura de la comunidad de gorgonáceos se determinó a lo largo de un perfil batimétrico en la costa suroeste del Pacífico Mexicano. La composición de especies se realizó a través de una revisión y recolecta de especímenes entre 0 y 70m de profundidad en 15 sitios de muestreo. La caracterización de la estructura de la comunidad se realizó en seis sitios, en los cuales se colocaron tres transectos de 10m2 cada uno a 5, 10, 20 y 25m de profundidad. Se encontraron 27 especies de gorgonáceos pertenecientes a seis géneros y tres familias; aunque seis especies requieren ser confirmadas. La mayor riqueza de especies se registró entre 40 y 70m. La estructura de la comunidad entre 5 y 25m de profundidad mostró la existencia de dos zonas con la misma composición de especies pero con diferente abundancia relativa: una somera entre 5 y 10m de profundidad, caracterizada por una mayor abundancia de gorgonáceos y dominado por colonias de Leptogorgia cuspidata y Leptogorgia ena y una zona profunda entre 20 y 25m de profundidad, caracterizada por una baja abundancia de gorgonáceos y dominada por colonias de Leptogorgia alba.

Gorgonians are important components of coastal ecosystems, as they provide niches, natural compounds with medical applications and are used as bioindicators. Species composition and assemblage structure of gorgonians (Anthozoa: Octocorallia) were studied along a bathymetric profile in the Southern Mexican Pacific coast. Species composition was based on specimens collected within a depth range of 0-70m in 15 sites. The relative abundance of species was determined in six sites at four depths (5, 10, 20 and 25m) using three 10m2 transects at each depth level. Twenty-seven species of gorgonians belonging to six genera and three families were registered. The species composition varied with depth: 11 species were distributed between 0-25m depth, while 17 species were found between 40-70m depth interval. The shallow zone is characterized by a relatively large abundance of gorgonians, dominated by colonies of Leptogorgia cuspidata and L. ena. In contrast, the deepest zone was characterized by relatively low abundance of gorgonians, dominated by L. alba, the only species observed in both depth intervals. The similarity analysis showed differences in the composition and abundance of species by depth and site, suggesting that the main factor in determining the assemblage structure is depth. Results of this study suggest that the highest richness of gorgonian species in the study area may be located at depths of 40-70m, whereas the highest abundances are found between 5 and 10m depth. This study represents a contribution to the poorly known eastern Pacific gorgonian biota. La composición de especies y estructura de la comunidad de gorgonáceos se determinó a lo largo de un perfil batimétrico en la costa suroeste del Pacífico Mexicano. La composición de especies se realizó a través de una revisión y recolecta de especímenes entre 0 y 70m de profundidad en 15 sitios de muestreo. La caracterización de la estructura de la comunidad se realizó en seis sitios, en los cuales se colocaron tres transectos de 10m² cada uno a 5, 10, 20 y 25m de profundidad. Se encontraron 27 especies de gorgonáceos pertenecientes a seis géneros y tres familias; aunque seis especies requieren ser confirmadas. La mayor riqueza de especies se registró entre 40 y 70m. La estructura de la comunidad entre 5 y 25m de profundidad mostró la existencia de dos zonas con la misma composición de especies pero con diferente abundancia relativa: una somera entre 5 y 10m de profundidad, caracterizada por una mayor abundancia de gorgonáceos y dominado por colonias de Leptogorgia cuspidata y Leptogorgia ena y una zona profunda entre 20 y 25m de profundidad, caracterizada por una baja abundancia de gorgonáceos y dominada por colonias de Leptogorgia alba.

12 pages, 7 figures, 3 tables, Submarine canyons are known as one of the seafloor morphological features where living cold-water coral (CWC) communities develop in the Mediterranean Sea. We investigated the CWC community of the two westernmost submarine canyons of the Gulf of Lions canyon system: the Cap de Creus Canyon (CCC) and Lacaze-Duthiers Canyon (LDC). Coral associations have been studied through video material recorded by means of a manned submersible and a remotely operated vehicle. Video transects have been conducted and analyzed in order to obtain information on (1) coral bathymetric distribution and density patterns, (2) size structure of coral populations, and (3) coral colony position with respect to the substrate. Madrepora oculata was the most abundant CWC in both canyons, while Lophelia pertusa and Dendrophyllia cornigera mostly occurred as isolated colonies or in small patches. An important exception was detected in a vertical cliff in LDC where a large L. pertusa framework was documented. This is the first record of such an extended L. pertusa framework in the Mediterranean Sea. In both canyons coral populations were dominated by medium and large colonies, but the frequent presence of small-sized colonies also indicate active recruitment. The predominant coral orientation (90° and 135°) is probably driven by the current regime as well as by the sediment load transported by the current flows. In general, no clear differences were observed in the abundance and in the size structure of the CWC populations between CCC and LDC, despite large differences in particulate matter between canyons, The authors acknowledge Fugro Survey, AOA Geophysics and the Universitat de Barcelona for providing the Cap de Creus Canyon multibeam bathymetry, and Serge Berne and IFREMER for providing the Lacaze-Duthiers Canyon ´multibeam bathymetry. We are indebted to the crews of the RV García del Cid and the Minibex, the JAGO team (J. Schauer and K. Hissmann) from IFM-GEOMAR (Kiel, Germany) and the scientific team onboard the Minibex during the MEDSEACAN sampling cruises; without their help it would not have been possible to carry out the field work. This work was funded by the European project LIFE+INDEMARES “Inventario y designacion de la red natura 2000 en areas marinas del estado espanol” (LIFE07/NAT/E/000732), and HERMIONE (Grant ˜Agreement Number 226354), the Spanish project DEEP CORAL (CTM2005-07756-C02-02/MAR), the Acciones Complementarias (CTM2005-24174-E, CTM2006- 27063-E/MAR, CTM2007- 28758-E/MAR), and the Agence des Aires Marines Protegées ´ (AAMP) for organizing and financing the MEDSEACAN cruises.A. G., C. O., T. M. and C. L. I. were supported by I3P and JAEDOC contract of the Consejo Superior de Investigaciones Cientificas