The Sponge Community of a Semi-Submerged Mediterranean Cave

Abstract. The sponge fauna of a semi-submerged cave from the Tremiti Archipelago (Adriatic Sea) was studied, and its distribution was analyzed in relation to abiotic (water-movement and light gradients) and biotic (algae and anthozoan substrate cover) ecological factors. Fifty-five species of sponges were recorded. The number of species and the abundance values of sponges increase in the first part of the cave, then progressively decrease, with a sharp fall at the end of the cave. The quick disappearance of algae along the light gradient allows sponges to thrive in the first portion of the cave. The subsequent, progressive decrement of sponges could be the result of food depletion phenomena due to a long persistence of the water body in this long cavity. A high water-turbulence, due to the peculiar morphology of the cave and indicated by the recorded values of water-movement, occurs at the end of the cavity and probably determines the sharp decrement of sponges in the inner portion of the cave. This turbulence may also explain the absence of typical still-water cave species and probably affects the type of development (shape, overgrowth) of the sponges in the community.     

Water Flow, Trophic Depletion, and Benthic Macrofauna Impoverishment in a Submarine Cave from the Western Mediterranean

Abstract. Biotic zonation and severe impoverishment of benthic macrofauna are two of the most conspicuous features of submarine caves. The prevailing explanation assumes trophic depletion caused by reduction of water flow. However, no isolation of water was found in the studied Catalan submarine cave, even in the wall microlayer. Fluorescein diffusion was so fast that it was detectable everywhere in the cave already only a few minutes after the injection. The rate of dissolution of plaster spheres was even greater in the cave than in a nearby tunnel – without benthic macrofauna impoverishment – showing a considerable water flow. The oxygen concentration of water in dialysis bags placed at varying distances from the cave walls showed that no wall microlayer gradients were present.
Biochemical gradients did not indicate any decrease in food supply. Although photosynthetic pigment concentration generally decreased inside the cave, and although the gradients were not linear but formed different patterns throughout the cave, the BOD₅, the POM, the C:N ratio, the [³H]-thymidine incorporation rate, and the ETS activity were higher in the inner part of the cave. There was an accumulation of detritic material and bacteria in the inner parts that constitute a plausible food supply for benthic macrofauna.
If neither water motion nor food supply can be invoked, research into the causes of zonation and disappearence of benthic macrofauna is proposed to be carried out on biotic interactions and behavioural processes.     

The Sponge Community in a Semi-Submerged Temperate Sea Cave: Density, Diversity and Richness

Abstract. The sponge communities inhabiting a temperate semi-submerged sea cave were investigated at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. Thirty-one species of sponge were reported, the majority of which exhibited either an encrusting or massive morphology. Sponge density (averaged over depth) increased with horizontal distance (5  m intervals) into the cave until approximately 30  m, corresponding to the maximum algal intrusion (algal information from Norton et al. , 1971) . Species diversity and richness (averaged over depth) were highest at 10  m horizontal distance from the cave entrance. Variability in sponge density, diversity and richness was observed with increasing vertical depth (0.5  m intervals) at most horizontal intervals sampled (5  m apart). These three variables increased initially with depth, but then decreased towards the seabed. Bray-Curtis Similarity Analysis and Multi-Dimensional Scaling (MDS) showed cave sponge community composition to have greater similarity (50 %) with local loose rock habitats than the nearby cliffs. Similar processes structuring cave and loose rock sponge communities may account for this situation. Information collected from this and previous studies on the biotic (algal communities, other fauna and competition) and abiotic factors (water flow rate, depth, aerial exposure, light, cave morphology, nutrient depletion and humidity) affecting this and other caves is discussed with respect to its influence on the sponges inhabiting different parts of the cave. Although horizontal zonation patterns have been considered analogous to vertical distribution patterns for algal communities (due to similar decreases in light), this was not the case for the studied sponge communities.     

Horizontal Transfer of Matter by a Cave-Dwelling Mysid

Abstract. The role of a cave-dwelling mysid population as a matter carrier was evaluated in a cave of the Medes Is. (NW Mediterranean) during 1988–89. Hemimysis spehmcola (Ledoyer , 1963) is a gregarious mysid whose swarms migrate daily from the inner end of the cave - where they remain during the day–to the exterior where they feed during the night. Fecal pellet composition, pellet egestion and pellet decomposition were measured in order to evaluate the transfer of matter by mysids. Based on the strong daily behavioural rhythms of these mysids. special importance was attached to the sampling frequency (every 2 h). In order to assess seasonal variability, four daily cycles were evaluated within a year. In situ incubations were carried out to determine changes on the egestion rates, morphology, weight and composition (AA. C: N ratios) of pellets in the course of a day. The number of pellets deposited inside the cave was estimated using containers distributed along the cave bottom by SCUBA divers. Fecal pellets showed an amorphous composition, whereby diatom frustules, dinoflagellate loricae and coccolithoporids were very scarce. About 25% of the body weight were estimated to be egested daily as fecal pellets, suggesting a detritivorous feeding habit. The population oscillated seasonally between 1 and 12 millions. Individuals egested between 1.6 and 3.5 pellets a day into the cave, each averaging from 9.4 to 11.9 μg DW, 0.5 to 1.0 μg C and 0.046 to 0.27 μg N. Therefore, the population carried daily about 20 407 g DW POM. 2–21 g C and 0.5 2.7 g N from outside to inside the cave. Pellets decomposed very quickly; between 20 to 50% of both C and N were released from pellets in less than 2 h after egestion. Oxidation of pellets theoretically consumes an amount of oxygen which agrees with the high BOD values previously reported for this cave. Marine caves are generally viewed as strictly oligotrophic systems; dense mysid populations, however, could strongly modify the trophic relationships in marine caves.     

中国龙虾栖息习性的观察

于1999年5月在集美大学水产学院海水养殖试验场进行中国龙虾栖息习性的试验观察。结果表明 ,正常温度、盐度条件下 ,中国龙虾有隐匿穴居、昼伏夜出的栖息习性 ,喜欢栖息于紧身或身体易于找到依靠的水平洞穴中 ,并有同穴共居现象 ,低层洞穴的栖息率高于高层洞穴 ;温度低于12℃时 ,中国龙虾夜间也很少离穴活动 ,温度低于8.6℃或高于34℃ ,盐度低于14.1或高于44.6时 ,中国龙虾都会逃离洞穴     

Occurrence and distribution pattern of Palaemon spp. shrimps in a shallow submarine cave environment: a study case in South‐eastern Italy

The common shrimps of the genus Palaemon are often reported as living in Mediterranean submarine caves. The present study quantifies the distribution pattern of a Palaemon spp. populations throughout 1 year of observations in a shallow submarine cave in South‐eastern Italy, Ionian Sea. The cave was subdivided into six sectors from the entrance towards the inner portion of the ‘blind cave’ and 16 dives (four per season, during both day and night) were performed with SCUBA equipment. The population was estimated in situ using visual census. Four different species of Palaemon were identified. This study has shown that Palaemon spp. assemblages live throughout the year in submarine caves. Moreover, the results suggest submarine caves play an important role in the biology of Palaemon spp. populations, by providing refuge, juvenile recruitment and food resources.     

The Sponge Population of the Cabrera Archipelago (Balearic Islands): Characteristics, Distribution, and Abundance of the Most Representative Species

Abstract. The abundance, distribution, and species richness of the littoral sponges (0–55 m) from the Cabrera Archipelago (Balearic Islands) were studied along light gradients from the surface to the sea bottom and from cave mouths to their inner parts. A total of 98 species (11 Calcarea and 87 Demospongiae ) were recorded, 8 of which are new records for the Spanish coast.
Cluster and correspondence analyses enabled the identification of a sciophilous sponge group including three subgroups: sponges found only in semi-dark cave habitats, a subgroup common to the coralligenous, precoralligenous, and semi-dark cave biocoenoses, and a third subgroup exclusive to the coralligenous biocoenosis. A small number of photophilic species and other species having a wide bathymetric distribution made up another separate group. No species clusters for the different semi-sciophilous (either fleshy or carbonate) or photophilic seaweed communities were discernible. The number of sponge species was negatively correlated with the irradiance level.     

洞库扩挖截面和施工方案选择

为了取得良好的经济效益和利用原有洞库良好的地理位置,洞库扩挖成为岩石洞库施工中一项非常值得考虑的方案。但是目前关于洞库扩挖所涉及到的截面选择和施工方案等问题研究还很少。对岩石洞库扩挖截面和施工方案选择进行了综述,并根据工程实例进行了各施工方案的比选。     

Alien biodiversity in Mediterranean marine caves

The number of alien species in the Mediterranean Sea is increasing rapidly, but few attempts have been made to evaluate impacts on specific habitat types. The present study investigated alien biodiversity in Mediterranean marine caves, both by contributing new records of Eastern Mediterranean cave aliens, and by reviewing the scattered existing literature; the main goals were to highlight potential impacts and investigate the importance of cave environments for the expansion of alien species. Seven new alien species were found in marine caves of the Aegean and Ionian seas, raising the total number of aliens reported from Mediterranean marine caves to 56 species, classified as molluscs, cnidarians, bryozoans, polychaetes, crustaceans, macroalgae, fishes and tunicates. Most cave aliens (66%) were recorded from the Southeastern Levantine coasts, specifically from Lebanese caves. Shipping and Lessepsian migration have been suggested as the main pathways of alien introduction into caves of the Mediterranean Sea. The comparison of alien cave biodiversity with the updated Mediterranean alien inventory (32 species added to the latest inventory) showed similar patterns and trends for species richness, biogeographical origin and major introduction pathways, corroborating previous findings on the high local representativeness of Mediterranean cave biodiversity. Alien species seem to have invaded mostly the entrance and semi‐dark zones of shallow and/or semi‐submerged caves and tunnels, whereas only a few have reached the dark inner sectors or caves of the anchialine type; thus, the unfavourable cave environment seems to be naturally protected from impacts related to opportunistic invasive species, at least to a certain point. Currently there is no research confirming any direct impacts of alien biota on the native cavernicolous one. However, some issues have emerged, implying potential threats that need to be further explored: (i) the presence of a considerable proportion of aliens in most studied marine caves of the Southeastern Mediterranean basin, (ii) the recently observed population explosion of alien cave‐dwelling fishes in the same area, (iii) several indications that alien diversity in marine caves is much higher than we know today. Quantitative surveys and monitoring schemes are needed in order to evaluate potential effects of alien diversity on cave community structure and the role of marine caves as stepping stones for its expansion in the Mediterranean.     

桂林洞穴滴水对应CaCO3沉积物的稳定同位素特征与环境意义

桂林地区降水及茅茅头大岩滴水滴速和现代碳酸盐的碳氧同位素研究表明:(1)滴水沉积的δ18O达到了同位素沉积平衡,洞穴滴水的δ18O与同期降雨的δ18O值呈正相关关系;(2)在旱季和湿季交替时,滴水δ18O值滞后于降雨δ18O,受活塞效应的影响;(3)δ13C难以达到同位素沉积平衡,主要受滴水动力学影响;(4)同一洞穴不同滴水对环境的响应不同,如果洞穴顶板覆盖较厚,水分在土壤和岩层中滞留时间较长,滴水则反映受到平滑作用的降雨,反之则波动较大.     

Organic pollution of an inland marine cave from Bermuda

Inland marine caves have served as biological refugia and, as such, frequently contain unique assemblages of taxonomically significant relict populations known only from a single cave or cave system. However, the absence of photosynthesis in this totally lightless environment and the presence of a highly stratified water column and long residence times for cave waters, characteristically result in depleted dissolved oxygen levels. Under such circumstances, organic pollution, even at low levels, can produce anoxic conditions and may consequently result in the extinction of entire species of cavernicolous fauna. We here present data on the normal environment of marine caves in Bermuda and cite as an example a cave which has become grossly polluted as a result of indiscriminate dumping.     

塔里木盆地塔北露头区的古岩溶发育模式

目前塔里木盆地海相碳酸盐岩的油气勘探已进入高峰期,为弥补钻井岩心资料不足,进一步认识井下岩溶发育规律及发育模式特征,开展塔北露头区奥陶系风化壳古岩溶缝洞系统发育特征及发育模式研究。研究表明,岩溶发育主要受控于岩性因素和不整合面,主要发育层位为一间房组地层;主要岩溶作用期为吐木休克组／一间房组沉积间断岩溶期。为井下岩溶缝洞系统的认识及岩溶地质模型的建立提供了重要理论依据。     

Unexpected records of ‘deep‐sea’ carnivorous sponges Asbestopluma hypogea in the shallow NE Atlantic shed light on new conservation issues

Marine cave communities have been a continued source of ecological surprises, among other things because of their close ecological and evolutionary ties with the deep sea. The discovery of cladorhizid sponges, the deepest occurring poriferan family, in shallow Mediterranean caves in the 1990s was one such surprise, leading to the generally accepted hypothesis that the whole family was carnivorous, an unprecedented feeding mode for sponges. The recent observation of the cave species Asbestopluma hypogea in the Mediterranean bathyal, confirmed the view that some shallow caves can occasionally shelter otherwise deep‐dwelling species. Here we present new distribution data of A. hypogea, from deep Mediterranean locations, and for the first time from Atlantic locations. Among the new Atlantic records, the most surprising ones are located in three different geographic areas (Ria de Arousa, Groix Island and Cherbourg) of the NW European coasts, from the Iberian Peninsula to the English Channel, where A. hypogea reaches SCUBA depths (5–50 m), while not sheltered in marine caves. The carnivorous sponge however reaches its shallowest occurrence (5 m), in a small cave at Groix Island. The ecological significance of these discoveries, particularly the very patchy distribution and peculiar dynamics, are noteworthy, and the shallow occurrence of A. hypogea, together with other deep‐water or uncommon species, constitute unique assemblages that must be considered in conservation plans.     

三沙永乐龙洞洞内侧壁礁体矿物和元素组成及其晚更新世以来的形成演化

三沙永乐龙洞深度在300m左右,是目前全球已知最深的海洋蓝洞,但是对其性质和成因了解极其有限。本研究使用X射线粉晶衍射仪、X射线荧光光谱仪、AMS14C测年等分析测试方法对采自不同深度的洞壁礁体的矿物物相、元素含量和形成年代进行了测定,探讨了洞壁性质和龙洞的演化。研究结果表明:三沙永乐龙洞洞内侧壁矿物均属于碳酸盐矿物,包括文石、高镁方解石和低镁方解石,平均含量分别为49.0%、46.6%、14.3%,它们主要来自钙质生物碎屑;洞内侧壁的主要元素是Ca、Mg、Sr,平均含量分别为36.8%、0.98%、0.48%。三沙永乐龙洞是一个复合体,17m以上岩石年龄晚于7.5cal kaBP,是全新世海平面上升时期形成的现代珊瑚礁体,没有经历过海平面下降引起的成岩作用; 17—35m岩石形成时代早于25cal ka BP,是经历了大气淡水成岩作用的晚更新世喀斯特溶洞,且在高海平面时期于17—23m以浅的空间内广泛发育洞内珊瑚礁。     

多波束测深系统中凹凸变形地形的分析与处理

在平坦海区测量工作中,多波束测深系统质量监控窗口经常会显示出凹凸变形地形,如果处理不及时或处理不当,将会导致测量的海底地形呈现凹凸不平的伪地形,严重影响测量工程的质量。分析了多波束系统测量凹凸变形地形的原因,论述了在测量中以及数据后处理中解决测量凹凸变形地形故障的方法,实际应用证明方法有效、实用。     

The distribution of iodide and iodate in anchialine cave waters — Evidence for sustained localised oxidation of iodide to iodate in marine water

A study of inorganic iodine speciation in the waters of seven Croatian coastal caves is described. These are anchialine caves as they are connected hydraulically with Adriatic Sea surface water, with the tide inside the cave rising and falling with that outside, but replenishment of the water is restricted by the karst rock. In effect, the water in the cave probably acts more like a piston, and although moving slightly vertically, has a long residence time compared to a fully-flushing cave. Anchialine environments display a number of unusual features, e.g., a well-developed pycnocline, hypoxia and endemic fauna. Iodate and iodide were determined by differential pulse voltammetry and cathodic stripping square wave voltammetry, respectively. Low iodide concentrations (< 10 nM) have been consistently identified in the bottom water of the caves where concentrations of 90–100 nM would ordinarily be expected from intrusion of Eastern Adriatic surface seawater. Where total inorganic iodine concentrations behave conservatively with salinity the loss of the iodide implies oxidation to iodate. As iodide oxidation remains one of the enduring academic problems of the marine iodine system the study of iodine in anchialine caves may help unravel it. Iodate reduction was observed in mid-water, at the halocline, and mechanisms for the reduction involving either respiration or chemolitho-autotrophic bacteria are considered. The respiration mechanism is favoured because of enhanced alkalinity found in the near surface waters of the caves.     

Biogenic stalactites in submarine caves at the Cape of Otranto (SE Italy): dating and hypothesis on their formation

Submarine caves at the Cape of Otranto (SE, Italy) host pseudostalactites. Only recently have they been recognised as originating mainly from the marine tube worm Protula tubularia (Serpulidae, Polychaeta). Their formation depends on the adaptability, life history and behaviour of that species in the cave habitat. The dating of calcareous tubes in the pseudostalactite core represents the first attempt to describe the formation of such bio-construction, and the gregarious behaviour of the species. Calcareous tubes along the core axis of three pseudostalactites removed from the cave lu Lampiùne (Otranto, South East Italy) have been dated using the ¹⁴C method. Measures established ages from 2600 to 5000 years for the three structures. This extremely long period (when compared with the life span of each worm) suggests that each tube aggregation is the result of punctuated growth periods alternated with long standstill phases. At the end of a growth period, each tube aggregation was covered with a brownish concretion, completing the pseudostalactite.     

亚洲季风区石笋氧同位素环境机理研究进展

洞穴石笋作为古气候研究重要载体之一,其氧同位素指标运用极为广泛,逐渐成为低纬甚至全球古气候变化的参比标准。然而,已有研究对洞穴碳酸盐沉积δ18 O气候意义的解译存在很大差异,包括洞穴温度、降雨量、降雨过程、大气环流模式等,亚洲季风区相关研究的分歧尤其突出,至今仍未统一。因此,洞穴古气候学界必须加强现代观测等机理研究,探明石笋δ18 O各种控制因子及其相互关系,充分发挥其气候地层学方面的优势,进一步促进区域间和全球气候对比。     

长岛地质遗迹成因与综合评价

对世界罕见的海洋地质遗迹--黄渤海分界线砾脊、海蚀栈道等成因进行了探讨.综合评价认为,长岛是开展海洋动力沉积作用和新生代以来全球气候与海平面变化研究的极佳基地;13处主要地质遗迹的美学价值半定量评价表明高观赏度者达69%.