Characterization of archaeal symbionts of sponges from the coral reef ecosystems of the Gulf of Mannar,Southeast coast of India

Sponges accommodate a diverse group of microorganisms with varied metabolic capabilities. The bacterial associates of sponges are widely studied while our understanding of archaeal counterparts is scanty. In the present study, we report the archaeal associates of two sponges, Pseudoceratina purpurea (NCBI barcode: KX454492) and Cinachyra sp. (NCBI barcode: KX454495), found in the coral reef ecosystems of Gulf of Mannar, India. Archaea in the water column was predominated by members of class Halobacteria of Phylum Euryarchaeota (97%) followed by a minor fraction (3%) of Nitrosopumilus sp. of phylum Thaumarchaeota. Interestingly, Thaumarchaeota was identified as the sole archaeal population associated with the two sponges studied, among which Nitrosopumilus sp. occuppied 80 and 100% of the sequences in the clone library of P. purpurea and Cinachyra sp. respectively. Other archaea found in the P. purpurea were Nitrososphaera (10%) and unclassified ones (10%). The study identified Nitrosopumilus sp. as a unique symbiotic archaeon of sponges, P. purpurea and Cinachyra sp. The existence of host driven factors in selecting specific associates from a diverse group of archaea in the environment may need further investigations.     

Length-weight relationship of six coastal fish species from Gulf of Mannar,South-east coast of India

The parameters ‘a’ and ‘b’ of length weight relationship of 6 species (Scolopsis vosmeri (Bloch, 1792), Engyprosopon macrolepis (Regan, 1908), Bleekeria murtii Joshi, Zacharia&Kanthan, 2012), Centriscus scutatus Linnaeus, 1758, Samaris cristatus Gray, 1831 and Iniistius bimaculatus Ruppell, 1829) are reported from the Gulf of Mannar, South east coast of India. The fish samples were collected from experimental trawling conducted twice a month during the period August to December 2012 and September to December 2013 at a depth ranging from 8.5 to 20.5 m. Three hauls were made in a day with each haul of one hour duration. The total length of the gear was 32 m with a cod end mesh size of 30 mm. The total length of the fish was measured to the nearest 0.1 cm and weight to the nearest 0.1 g.     

Cushion star (Culcita schmideliana) preys on coral polyps in Gulf of Mannar,Southeast India

Corallivore animals play vital role in coral reef ecology. Predation on corals by other organisms has not been studied properly in the Indian waters. This study reports the first observation of predation by cushion star (Culcita schmideliana) on coral polyps in Gulf of Mannar (GoM), southeast India. During our regular underwater surveys in GoM, C. schmideliana was found preying on hard coral Acropora formosa and soft coral Sarcophyton sp. at a depth of 3 m in Vilanguchalli patch reef. Though C. schmideliana has been sighted often under water, it has not been observed to predate on corals in GoM before. The area where predation was observed has a major population of hard corals (50.21%) besides seagrasses (8.36%) and soft corals (6.11%). Temperature anomalies and the consequent coral bleaching could be the factors making C. schmideliana prefer coral polyps.     

Comparative morphometry,biochemical and elemental composition of three marine sponges (Petrosiidae) from Gulf of Mannar,India

Abstract

Three marine sponges Neopetrosia similis, Xestospongia testudinaria and Petrosia nigricans from the Gulf of Mannar, Southeast coast of India were compared based on their morphometric parameters and their biochemical and elemental composition. These sponges showed differences inspicule : protein (spongin) ratio of 5:1, 11:1 and 13:1, respectively. Xestospongia testudinaria possessed the longest oxeae, 3.05 times than P. nigricans and 1.47 times than N. similis. Spectral analysis revealed that the spicules of these sponges are mostly composed of O (>50%) and Si (29–45%), whereas Al and Ca (4–5%) were additionally detected only in the spicules of P. nigricans. In contrast, the percentage elemental composition in pinacodermal sections was significantly different as O and Si were the maximum (23–50%); followed by Cl and Al as moderate (1–17%); and Na, S, Fe and Ca in minor quantities (0.2–6%). Cluster analysis and traditional taxonomic arrangements show that X. testudinaria and N. similis have a close relationship whereas P. nigricans was hypothesized to be their sister group. The present findings could be the key for identifying sponges in situ as well as determining whether sponges could be used to assess pollution in the sea.     

A coral reef refuge in the Red Sea

The stability and persistence of coral reefs in the decades to come is uncertain due to global warming and repeated bleaching events that will lead to reduced resilience of these ecological and socio‐economically important ecosystems. Identifying key refugia is potentially important for future conservation actions. We suggest that the Gulf of Aqaba (GoA) (Red Sea) may serve as a reef refugium due to a unique suite of environmental conditions. Our hypothesis is based on experimental detection of an exceptionally high bleaching threshold of northern Red Sea corals and on the potential dispersal of coral planulae larvae through a selective thermal barrier estimated using an ocean model. We propose that millennia of natural selection in the form of a thermal barrier at the southernmost end of the Red Sea have selected coral genotypes that are less susceptible to thermal stress in the northern Red Sea, delaying bleaching events in the GoA by at least a century.     

Petroleum production platforms as sites for the expansion of ciguatera in the northwestern Gulf of Mexico

Ciguatera is a common human disease of tropical, coral reef ecosystems acquired by consuming finfish-containing ciguatoxins (CTX). There are few records of this disease in the northwestern Gulf of Mexico, a region characterized by soft muddy bottoms that are considered poor habitat for the CTX source dinoflagellate Gambierdiscus toxicus. However, the approximately 4000 petroleum production platforms and hundreds of state-sponsored artificial reefs located in the Gulf of Mexico provide hard substrate and often support coral and other components of the tropical benthos. In addition to their role in their resource extraction, these oil production platforms are also popular sites for recreational fishing and sport diving. We examined these platforms as potential substrate for G. toxicus and report a first record of this species in the NW Gulf of Mexico. All the platforms (n = 6) examined harbored the dinoflagellate as an epiphyte on the fouling community, with three finds of G. toxicus associated with the pelagic macroalga Sargassum. Only minor toxicity (<0.15 ppb) was noted in two of 20 great barracuda (Sphyraena barracuda) examined. Tagging data suggest trans-Gulf migrations by barracuda are common; thus, we cannot determine if the toxicity was acquired locally or transported in migrating fish.These platforms are a clear example of how human activity has altered the environment in a way that allows expansion of a HAB population. The rapid increase in production platforms since 1942 has provided novel substrate in a sandy/muddy bottom environment generally considered to be poor habitat for these benthic dinoflagellates. These platforms create a unique habitat in the upper euphotic zone and serve as intersection points for fishermen and potentially toxic fish. Many Gulf of Mexico states have active programs to turn non-producing platforms into artificial reefs. Our results suggest that the use of these platforms as fisheries enhancement structures could have unintended consequences for human health, particularly if projected rising sea-surface temperatures over the next century alter benthic distributions and fish migration patterns. These concerns also extend to mariculture operations around oil production rigs or offshore wind farms, both of which would also add substrate for epibenthic microalgae.     

Coral communities in the northern part of the Gulf of Tonkin, south China Sea

The reefs and benthic communities of 15 islands in Ha Long Bay, listed by UNESCO as a world heritage site, have been studied using scuba. Two reef types have been distinguished: structured and unstructured reefs. The changes in the composition and structure of reef-building corals takes place in these reefs under conditions of heavy silting in the surrounding waters. Poritids that primarily form the reef carcass become dominant scleractinians. More than 250 species of macrobenthos are found; the greatest species diversity was recorded in the reefs of Bo Hung and Kong Do islands, which we recommend be organized into a national nature reserve.     

Holding steady: Little change in intensity or timing of bird migration over the Gulf of Mexico

Quantifying the timing and intensity of migratory movements is imperative for understanding impacts of changing landscapes and climates on migratory bird populations. Billions of birds migrate in the Western Hemisphere, but accurately estimating the population size of one migratory species, let alone hundreds, presents numerous obstacles. Here, we quantify the timing, intensity, and distribution of bird migration through one of the largest migration corridors in the Western Hemisphere, the Gulf of Mexico (the Gulf). We further assess whether there have been changes in migration timing or intensity through the Gulf. To achieve this, we integrate citizen science (eBird) observations with 21 years of weather surveillance radar data (1995–2015). We predicted no change in migration timing and a decline in migration intensity across the time series. We estimate that an average of 2.1 billion birds pass through this region each spring en route to Nearctic breeding grounds. Annually, half of these individuals pass through the region in just 18 days, between April 19 and May 7. The western region of the Gulf showed a mean rate of passage 5.4 times higher than the central and eastern regions. We did not detect an overall change in the annual numbers of migrants (2007–2015) or the annual timing of peak migration (1995–2015). However, we found that the earliest seasonal movements through the region occurred significantly earlier over time (1.6 days decade^?1). Additionally, body mass and migration distance explained the magnitude of phenological changes, with the most rapid advances occurring with an assemblage of larger‐bodied shorter‐distance migrants. Our results provide baseline information that can be used to advance our understanding of the developing implications of climate change, urbanization, and energy development for migratory bird populations in North America.     

基于MaxEnt模型的小兴安岭东北虎潜在生境适宜性评价

小兴安岭是东北虎的历史分布区之一,近年来东北虎数次重返小兴安岭,预示了小兴安岭东北虎种群恢复的可能性。为了探明小兴安岭作为东北虎栖息地的适宜程度,本文以我国小兴安岭及俄罗斯联邦阿穆尔州、犹太自治州为整体研究区域,利用该区域内东北虎出现点数据,采用Maxent模型,以植被、气候、地形、积雪4类环境数据为基础,分析自然环境条件下小兴安岭东北虎潜在生境的适宜性及空间分布。结果显示：小兴安岭东北虎潜在适宜生境面积为0.96×10⁴~1.03 ×10⁴ km²,主要位于小兴安岭北部和东部,中部、西部和东南部有少量分散适宜生境;次适宜生境面积为2.46×10⁴~1.76 ×10⁴ km²,主要位于适宜生境周边区域;叶灌层差异、蒸散量、归一化植被指数、叶面积指数等植被相关因素及降水季节性、最冷季降水量等气候因素是影响东北虎栖息地适宜程度的主要环境特征变量。小兴安岭仍具备东北虎种群生存的自然条件。     

北部湾儒艮现状的调查兼记印度洋白海豚

为了解北部湾中国水域儒艮的现状 ,于 2 0 0 0年 9月 15日至 11月 17日在广东、海南、广西三省区的沿岸海域进行了 36次舟船考察。调查结果表明 ,在北部湾的部分海域仍有儒艮存在 ,但数量比 2 0世纪 80年代已显著减少。建议把海南省西海岸近海的儒艮及其栖息地的保护作为最优先的海兽保护项目。另外在 11月 3日和 4日在广西壮族自治区北海市大风江口 (2 1°36′N ,10 8°5 4′E)的舟船考察中 ,还分别观察到约 7头和 4头印度洋白海豚的小群 ,它们属于在中国海域已知的唯一印度洋白海豚种群 ,建议广西合浦国家级儒艮自然保护区把印度洋白海豚也作为其重点保护对象之一。     

A late Devonian (Frasnian) coral-bafflestone reef at Houshan in Guilin, South China

Summary Givetian to early Carboniferous sediments of South China are characterized by carbonates. Middle and Late Devonian strata are best developed in the Guilin area. Reefs and organic shoals are recorded by various lithofacies types indicating the existence of an extended carbonate platform and a change of the composition of reef communities in time. Starting in the late Devonian, stromatoporoids and corals were replaced by algae that subsequently played an important role together with stromatoporoids, receptaculitids and fasciculate rugose corals in reef communities. In Houshan, 5 km west of Guilin, a coral-bafflestone reef occurs in the Frasnian strata, situated near an offshore algal-stromatoporoid reef. The coral reef was formed in a back-reef area adjacent to the inner platform margin. The coral-bafflestone reef is unique among the late Devonian reefs of South China with regard to the biotic composition. The reef is composed of fasciculate colonies ofSmithiphyllum guilinense n. sp. embedded within in packstones and wackestones. The height of colonies reaches 1 m. The community is low-diverse. The species ofSmithiphyllum occurring in the Frasnian reef complexes of Guilin exhibit a distinct facies control:Smithiphyllum guilinense occurs in or near to margin facies and formed bafflestone, constituting a coral reef whereasSmithiphyllum occidentale Sorauf, 1972 andSmithiphyllum sp.—characterized by small colonies with thin corallites—are restricted to the back-reef and marginal slope facies. The bush-like coral colonies baffled sediments. Algae and stromatoporoids (mainlyStachyodes) are other reef biota. Reef-dwelling organisms are dominated by brachiopods. The reefs are composed from base to top of five lithofacies types: 1) cryptalgal micrite, 2) peloidal packstone, 3) stromatactis limestone, 4) coral-bafflestone, and 5) pseudopeloidal packstone. The reef complex can be subdivided into back-reef subfacies, reef flat and marginal subfacies, and marginal fore-slope subfacies. The Houshan coral-bafflestone reef is not a barrier reef but a coral patch reef located near the inner margin of a carbonate platform.     

气候变化对东北濒危动物驼鹿潜在生境的影响

气候变化是造成生物多样性下降和物种灭绝的主要因素之一。研究气候变化对物种生境,尤其是濒危物种生境影响对未来保护物种多样性和保持生态系统功能完整性具有重要意义。以驼鹿乌苏里亚种(Alces alces cameloides)为研究对象,选取了对驼鹿分布可能存在影响的22个环境因子,利用最大熵(Maxent)模型模拟了驼鹿基准气候条件下在我国东北的潜在生境分布,并预测了RCP4.5和RCP8.5两种气候变化情景下2041—2060年(2050s)、2061—2080年(2070s)驼鹿潜在分布,采用接收工作曲线下面积(AUC)对模型预测能力进行评估。研究结果表明:最大熵模型预测驼鹿潜在生境分布的精度较高(平均AUC值为0.845),22个环境因子中,年均温、最暖季均温、年降水、平均日较差是影响驼鹿生境分布的主要因子。基准气候条件下,驼鹿的潜在生境面积占研究区域总面积的36.4%,潜在生境分布区主要在大、小兴安岭。随着时间的推移,研究区内驼鹿当前潜在生境面积明显减少,而新增潜在生境面积较少,总面积呈现急剧减少的趋势,其中RCP8.5情景减少程度大于RCP4.5情景。至2050s阶段,当前潜在生境面积平均将减少62.3%,新增潜在分布面积平均仅为3.6%,总潜在生境面积最高将减少65.6%,平均将减少58.8%;至2070s阶段,当前潜在生境面积平均将减少75.8%,新增潜在分布面积平均仅为1.9%,总潜在生境面积最高将减少93.1%,平均减少73.9%。空间分布上,驼鹿的潜在生境的几何中心将先向西北移动,然后再向高纬度地区西南方向迁移,至2050s阶段,潜在分布生境的几何中心在RCP4.5和RCP8.5情景下的迁移距离分别为183.5 km和210.8 km;至2070s阶段,相应情景下的迁移距离将缩短至28.7 km和33.8 km。潜在生境分布整体呈现向高海拔、高纬度迁移的趋势。     

Use of the green alga Ulva rigida C. Agardh as an indicator species to reassess metal pollution in the Thermaikos Gulf, Greece, after 13 years

The concentrations of metals (Mn, Pb, Fe, Zn, Cu, Cd,Co, Ni, Cr, Na, K, Ca, Mg) were determined in thegreen alga Ulva rigida, in the sediment andseawater of Thermaikos Gulf (Greece) during monthlysamplings in 1994–1995. This Gulf is the recipientof domestic and industrial effluents. Pb, Fe, Cu, Coand Cr concentrations in U. rigida at the studyarea were higher than those 13 years earlier andapparently came from different sources than those forZn, Cd and Ni. The relative abundance of metals inthe alga decreased in the order: Mg > Na > K >Ca > Pb > Fe > Mn > Zn > Cr, Cu > Ni >Co > Cd. Only Cu concentrations in the alga fromKalochori and Cd ones from Viamyl showed significantseasonal changes. Cu and Cd concentrations ingeneral followed the same pattern of variation, withminimum values in winter-spring. This pattern isdiscussed in relation to growth dynamics and tissueage. Only Pb concentrations in the alga showed asignificant positive correlation with concentrationsin the seawater. There were both positive andnegative correlations among some metals in the alga. It is concluded that U. rigida can be used as anindicator species, especially for Pb.     

Impact assessment of an invasive flatworm, Convoluta convoluta, in the Southern Gulf of Maine

Convoluta convoluta (Abildgaard 1806) is a small (2-3 mm long) acoellous turbellarian flatworm from Europe that has invaded the Gulf of Maine within the last 5 years. Although it has been reported in densities of up to 19 individuals/cm², its ecological impact remains unknown. In its native habitat, it consumes harpacticoid copepods and primary settling mussels <0.5-mm shell length. This study estimated the impact of C. convoluta on juvenile blue mussel populations (Mytilus edulis Linnaeus 1758) around the Isles of Shoals in the southern Gulf of Maine, USA as well as looking at their distribution in their new habitat. We surveyed worm densities at sites of differing wave exposure over three substrates (hard substrates, bladed algae, filamentous algae) to quantify patterns of worm abundance. We found worms on all substrate types with their highest abundances occurring in areas of maximal sunlight exposure and minimal physical disturbance. We showed a definite pattern of consumption of mussels in the lab and found C. convoluta to consume up to 35% of primary settling mussels in the field, but only under certain conditions. Per capita impact on juvenile mussels was found to vary greatly in correlation with mussel recruitment rate and water temperature, but not with the consumption of harpacticoids. Our results also suggested that per capita interaction strength was reduced by intraspecific density-dependent competition and water temperature. The overall impact of C. convoluta on mussel populations in the southern Gulf of Maine is therefore estimated to be minimal.     

Modelling climate,CO2 and management impacts on soil carbon in semi-arid agroecosystems

In agroecosystems, there is likely to be a strong interaction between global change and management that will determine whether soil will be a source or sink for atmospheric C. We conducted a simulation study of changes in soil C as a function of climate and CO₂ change, for a suite of different management systems, at four locations representing a climate sequence in the central Great Plains of the US.Climate, CO₂ and management interactions were analyzed for three agroecosystems: a conventional winter wheat-summer fallow rotation, a wheat-corn-fallow rotation and continuous cropping with wheat. Model analyses included soil C responses to changes in the amount and distribution of precipitation and responses to changes in temperature, precipitation and CO₂ as projected by a general circulation model for a 2 × CO₂ scenario.Overall, differences between management systems at all the sites were greater than those induced by perturbations of climate and/or CO₂. Crop residue production was increased by CO₂ enrichment and by a changed climate. Where the frequency of summer fallowing was reduced (wheat-corn-fallow) or eliminated (continuous wheat), soil C increased under all conditions, particularly with increased (640 L L^–1) CO₂. For wheat-fallow management, the model predicted declines in soil C under both ambient conditions and with climate change alone. Increased CO₂ with wheat-fallow management yielded small gains in soil C at three of the sites and reduced losses at the fourth site.Our results illustrate the importance of considering the role of management in determining potential responses of agroecosystems to global change. Changes in climate will determine changes in management as farmers strive to maximize profitability. Therefore, changes in soil C may be a complex function of climate driving management and management driving soil C levels and not be a simple direct effect of either climate or management.     

林隙干扰和升温对小兴安岭红松和臭冷杉径向生长的影响

通过建立小兴安岭阔叶红松(Pinus koraiensis)林内林隙与非林隙红松、臭冷杉(Abies nephrolepis)轮宽年表,分析林隙干扰(微环境差异)和1980年后显著升温对树木径向生长的影响。结果表明:升温减缓了非林隙红松生长,却加快了林隙红松生长;升温后,非林隙红松受温度影响减弱,而林隙红松则增强,林隙和非林隙红松径向生长与帕默尔干旱指数(Palmer drought severity index,PDSI)均由负相关变为正相关;林隙干扰导致臭冷杉径向生长减缓,升温导致林隙与非林隙臭冷杉年生长量均下降了约50%,非林隙木对温度的负响应要高于林隙木;升温后,5—10月温度对非林隙木抑制作用明显,非生长季(1—5月)降水对非林隙臭冷杉的抑制作用加强,而对林隙臭冷杉则由抑制变为促进;PDSI与非林隙臭冷杉由升温前的负相关变为升温后的正相关,而林隙臭冷杉则负相关更显著;林隙干扰减少耐荫喜湿树木径向生长,而对阳性树种影响不大或略有增加;林隙木比非林隙木更易受外界环境变化的影响,林隙干扰可使喜湿耐荫树种提前适应暖干环境,以提高了对升温适应性;升温导致林隙木与非林隙木年轮气候响应差异变大。     

1996-2015年滇西北香格里拉植被净初级生产力变化

地处青藏高原东南缘的滇西北香格里拉,其植被NPP的时空格局变化,对于深入了解青藏高原区域植被对气候变化的响应具有重要的科学意义。基于地面气象数据和MODIS-NDVI等遥感数据,运用改进的CASA模型,估算了1996—2015年香格里拉区域不同植被类型NPP,分析探讨了区域植被NPP的演变特征及其对气候变化的响应规律。研究显示:1)1995—2015年间,香格里拉区域6—8月平均气温总体呈上升趋势,增速为0.037℃/a; 6—8月总降水量为373.1 mm,呈微弱下降趋势;20年间辐射量基本维持波动稳定状态;2)1996—2015年,香格里拉区域6—8月最大月植被NPP平均值为176.9 gC/m~2,不同植被类型的变化范围为128.9—286.9 gC/m~2;空间格局上,表现为"从西北、东南及金沙江沿岸向中部递减"的特征;3)香格里拉区域植被NPP显著地受到气温变化的调控(P<0.05),20年间随着气温的持续升高,区域NPP总体呈增加趋势;4)区域植被NPP未表现出受降水变化的显著影响(P>0.05),水分条件对区域植被NPP未形成限制性的影响作用。区域内植被NPP...