Macrofaunal Composition Research Articles

Sampling effort required to recover the main gradients in marine benthic species composition

AbstractMarine benthic surveys and monitoring programs may have several goals. When the aim of such studies is to reveal and describe gradients in species composition, the gain in ecological insight achieved by the study depends on how well the spatial variability of species’ occurrence and abundance within the study area is covered by the sampling design. The common practice in such programs is to collect four or five grab samples from each visited site to capture the site's species composition. The rationale for this practice is based on the aim of capturing a large proportion of species at a specific site (i.e. point). We argue that this practice has been established without taking Iterative approaches into account, such as decreasing the sampling effort at each site and instead increase the number of sites visited. The collection and processing of data from marine sediment ecosystems are time‐consuming and, thus, expensive. Therefore, finding the optimal trade‐off between the number of sites visited and the number of samples per site is important. We examined this trade‐off by exploring how reduction of sampling effort per site affects the stability and recovery of gradients in species composition of marine benthic macrofauna. Our full data set consisted of four grab samples from each of 28 sites from the inner part of the Oslofjord, SE Norway. Procrustes analysis and calculation of Kendall's rank correlation coefficients showed that the main gradient in species composition extracted by detrended correspondence analysis of data sets with reduced per‐site sampling effort closely resembled the main gradient extracted for the full data set. Our results therefore suggest that marine benthic surveys that aim to identify the main gradient structure of species composition and relate this structure to main environmental complex gradients are likely to benefit from reducing the sampling effort at each site and, instead, increasing the number of visited sites. We argue that coverage of both the variation in species composition and the environment in the study area will then be improved. Monitoring programs with other aims than to identify the main gradients in species composition may also benefit from the adoption of a many‐sites, one‐sample sampling strategy. This may be particularly true if additional sampled sites are based on a stratified sampling strategy that ensures that the spatial variability in the study area is accounted for.

Bacterial and macrofaunal communities in the sediments of the West Gironde Mud Patch, Bay of Biscay (France)

Changes in (1) main sediment characteristics, and (2) benthic bacterial and macrofaunal communities were simultaneously addressed along an inner–outer transect within the West Gironde Mud Patch (Bay of Biscay, NE Atlantic), through the sampling of three stations (E: inner part, C: central part and W: outer part) during July 2010. Except in the top centimetre where a sandy layer was found at station E, all sediments were muddy and tended to be coarser and richer in photosynthetic pigments and particulate organic carbon and nitrogen at stations C and W than at station E. Maximum oxygen penetration depth was also lower at station E than at stations C and W. These results are consistent with: (1) the occurrence of strong hydrodynamics precluding current sedimentation in the inner part of the WGMP, and (2) conversely, inputs of particles originating from the Gironde Estuary in its central and outer part. Prokaryotic cell abundances were lower at station E than at stations C and W. Bacterial community composition also differed more clearly at station E as compared to stations C and W. Conversely, macrofaunal abundances and species richness decreased monotonously from station E to station W (i.e., along the inner–outer gradient). Macrofaunal composition strongly differed at station E on one side, and stations C and W on the other side. These results are consistent with the current paradigm regarding the long term effect of major rivers on benthic macrofauna given that strong hydrodynamics at station E precludes the sedimentation of fine particles originating from the Gironde Estuary. At last, we found no overall correlation between benthic bacterial and macrofaunal compositions, which may however clearly result from limitations in our sampling design.

五大连池药泉山大型土壤动物对旅游踩踏的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 五大连池药泉山大型土壤动物对旅游踩踏的响应 DOI: 10.5846/stxb201603230518 作者: 作者单位: 哈尔滨师范大学;黑龙江大学,哈尔滨师范大学,黑龙江大学,北京林业大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41101048） Responses of soil macrofaunal communities to tourism trample in the Wudalianchi Yaoquan Mountains Author: Affiliation: Harbin Normal University;Heilongjiang University,Harbin Normal University,Heilongjiang University,Beijing Forestry University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以黑龙江省五大连池世界地质公园的药泉山为研究对象，按照距离游道的远近分为重度踩踏区，轻度踩踏区和非踩踏区3种踩踏干扰强度，分析大型土壤动物数量，群落组成，多样性对旅游踩踏干扰的响应。研究结果表明不同干扰区之间大型土壤动物类群数量差异显著（P<0.001），重度踩踏区显著低于轻度踩踏区和非踩踏区。不同干扰区大型土壤动物个体数差异明显（P<0.001），其中轻度踩踏区个体密度最大（68头/m2），重度踩踏区个体密度最小（10头/m2）。不同踩踏强度干扰区H’指数差异明显（P<0.05），轻度踩踏区及非踩踏区的多样性显著高于严重踩踏区。典型对应分析表明旅游踩踏主要通过改变土壤理化特性而影响大型土壤动物的组成及其多样性，重度踩踏区、轻度踩踏区和非踩踏区对大型土壤动物影响最显著的因子分别为土壤全氮含量，土壤含水率和土壤全磷含量。 Abstract:Trampling is widespread among various recreational activities, and this can become a significant problem as it represents a major disturbance affecting the vegetation and soil surface horizon. Soil macrofauna, mainly in the soil surface horizon, are good indicators for studying the impact of human activities. In the present study, Yaoquan Mountain of Wudalianchi World Geo-park was considered as a study example in 2012. The areas surrounding tourism trails were divided into no-trampling, mid-trampling, and high-trampling plots, which were divided based on three different interference types. The effect of human trampling on soil macrofaunal communities at a depth of 0-10 cm were studied along an increasing distance from the tourism trail of Yaoquan Mountain. A completely randomized design, including three replicates from three trampling interference sites, was used. Soil macrofauna were separated by hand, and were identified and counted. Soil bulk density, soil moisture content, soil organic matter content, total nitrogen content, and total phosphorus content were measured from each site. Our study evaluated the structure, composition, diversity, and distribution of soil macrofauna in three different tourism trample types, and assessed the impacts of human activity. The results were summarized as the following aspects:The total number of soil animal genera was significantly different in the three disturbance degree sites (P<0.001) and the least number of genera occurred in high trampling sites. The individual density of soil macrofauna was significantly different from the other kinds of soil animal fauna in the three disturbance degree sites (P<0.001), the maximum value was in the mid-trampling plots (68 ind./m2), and the minimum value was in the high-trampling sites (10 ind./m2). The Shannon index (H') of soil micro-fauna were seriously affected by trampling (P<0.05), and the high trampling sites had the lowest H' index. A canonical correspondence analysis indicated the soil macrofaunal distribution in the mid-trampling and high-trampling plots differed from the no-trampling plots. The main factor affecting soil macrofauna distribution was soil total nitrogen content, soil moisture content, and total phosphorus content in no-trampling, mid-trampling, and high-trampling plots, respectively. 参考文献 相似文献 引证文献

Impact of dike age on biodiversity and functional composition of soilmacrofaunal communities in poplar forests in a reclaimed coastal area

Four patches of poplar forest with different dike histories (about 30 to 200 years) were selected from the coastal area of Yancheng, China, for detecting the effect of dike age on soil macrofauna. A total of 825 individuals belonging to 21 taxonomic groups were collected. Omnivorous, phytophagous, predaceous, and saprophagous groups were classified on the basis of diet. Higher biodiversity values were observed in the forests with longer dike histories (100 and 200 years) than in those with shorter dike histories (30 and 50 years). By principal coordinate analysis, the soil macrofaunal communities from the forests were distinguished as three groups with shorter or longer dike histories (30 years, 50 years, and above 100 years). One-way ANOSIM analysis revealed significant differences among soil macrofaunal communities (P < 0.050), except for those with longer dike histories (100 and 200 years, P = 0.217). The groups of omnivorous and predaceous macrofauna showed no significant differences in taxonomic richness and abundance among habitats, while significant differences were observed between the other functional groups. A significant difference in functional composition between the soil macrofaunal communities in the forests with dike ages of 30 and 100 years was found with the chi-square test (P = 0.027). The biodiversity and functional composition of soil macrofauna was significantly affected by dike age in the reclaimed coast.

The adoption of no-till instead of reduced tillage does not improve some soil quality parameters in Argentinean Pampas

No-till (NT) has been recognized worldwide as a more suitable system than tillage for enhancing soil quality. However, several concerns remain about its conservative nature, especially when it is performed either without cover crops or appropriate rotation schedules, and when it is accompanied by the usage of high amounts of agrochemicals. In this paper, we study some soil quality parameters when NT is adopted instead of reduced tillage, as well as the relevance of soil physical and chemical properties to explain the impact of management systems on soil macrofauna. We compared NT and reduced tillage (RT) systems, using natural grasslands (GR) as reference. We hypothesised that (1) soil quality will decline in both agricultural systems compared to the grassland but this declination will be less in no-till than in reduced tillage, and that (2) the changes in macrofauna community could be explained by changes in physical and chemical soil properties. Soil cover, organic matter, pH, moisture content, bulk density and mechanical resistance were assessed as indicators of soil physical and chemical quality. Soil macrofauna abundance and composition was determined by the TSBF method. We rejected our first hypotheses since from the assessed parameters only soil moisture content and spider abundance were favoured in NT compared to RT. Changes caused by both systems in the macrofauna composition (especially in soil inhabitants) were mainly explained by soil physical and chemical attributes. The ordination of sites according to canonical correspondence analyses clearly shows the influence of the management systems in the relationship between macrofauna assemblages and soil physical and chemical parameters; especially in the upper 30cm of soil. GR had both a better soil physical and chemical quality and a higher abundance of the main macrofauna taxa (earthworms, beetles and ants) compared to agricultural systems. NT and RT were similar, sharing low earthworm and ant abundance and high potworm abundance. Our results show that adopting NT instead of RT does not favour assessed soil quality parameters. Thus, NT is questioned as a system which enhances soil quality, at least in the way it is performed by most farmers from Argentine Pampa.

Macrobenthos in the central Arabian Gulf: a reflection of climate extremes and variability

The arid subtropical ecosystem of the central Arabian Gulf was used to explore the combined effects of low primary productivity, high salinities, and variable temperatures on the composition and structure of benthic macrofauna at 13 sites encircling the Qatar Peninsula in winter and summer (or late spring) of 2010 and 2011. The low abundance, biomass, and remarkably high species turnover may be a reflection of the oligotrophic, thermally variable, hypersaline coastal environment. The number of species and within-habitat diversity was lowest in the highest salinities but increased with finer-grained sediments and lower salinity. A remarkable temporal variation in species composition observed may reflect insufficient primary production to sustain new populations recruited from the seasonal exchange of water from the adjacent Sea of Oman. Low abundances accompanied by continued replacement of species may be a “new model” for extremely arid conditions associated with global warming.

Impact of deep-water fish farms on benthic macrofauna communities under different hydrodynamic conditions

In this study the environmental impacts of two fish farms located over deep water (180–190m) were compared. MC-Farm was located at a site with slightly higher water currents (mean current speed 3–5cms−1) than LC-farm (<2cms−1). Macrofauna composition, bioirrigation and benthic fluxes (CO2 and NH4+) were quantified at different stages of the production cycle, revealing very different impact of the two farms. Macrofauna abundance and bioirrigation were stimulated compared to a non-impacted reference site at MC-farm, while macrofauna diversity was only moderately reduced. In contrast, macrofauna communities and related parameters were severely impoverished at LC-Farm. This study suggests that deep-water fish farms should not be sited in low current areas (<2cms−1), since this will hamper waste dispersal and aggravate environmental impacts. On the other hand, fish farming at slightly more dynamic sites can lead to stimulated benthic macrofauna communities and only moderate environmental impacts.

Generalized assessments of composition, quantitative distribution and biomass of benthic macrofauna on the shelf and slope in the North-West Pacific

Generalized assessments of composition, quantitative distribution and biomass of benthic macrofauna on the shelf and slope in the North-West Pacific

The effect of pesticides on the composition of aquatic macrofauna communities in field ditches

Ditches surrounding agricultural fields in the Netherlands are predominantly used for flood control, and they accommodate aquatic plant and animal species. Studies addressing the effects of pesticides in combination with abiotic and biotic factors on aquatic biota in ditches are scarce. The current study aimed to investigate the effects of pesticides along with environmental factors, presence of other biota and time on the community composition of aquatic macrofauna in ditches next to flower bulb fields and pastures. Macrofauna samples and environmental data were collected during two consecutive years. Ponds in a sandy dune area of a nature reserve next to the polders were sampled as control sites. Data was analyzed with the variance partitioning procedure based on the redundancy analysis (RDA). The total variance in macrofauna community composition was divided into the variance explained by pesticides, environmental factors (water chemistry parameters and macrophyte coverage), time (study year and the number of the month), shared variance, and unexplained variance. The total explained variance in macrofauna community reached 22.6%. The largest proportion of explained variance was attributed to environmental factors (10.1%) followed by pesticides (5.4%) and time (4.8%). When each macrofauna group was analyzed separately, presence of other biota and environmental factors explained the largest proportion of variance in most of the macrofauna groups. Results of the study indicate that environmental factors, biotic interactions and temporal variation influence freshwater macrofauna considerably along with pesticides. We suggest that environmental managers should consider the multiple stressor contexts of aquatic ecosystems.

Combined effects of wrack identity and solar radiation on associated beach macrofaunal assemblages

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 531:167-178 (2015) - DOI: https://doi.org/10.3354/meps11304 Combined effects of wrack identity and solar radiation on associated beach macrofaunal assemblages Iván F. Rodil1,*, Celia Olabarria2, Mariano Lastra2, Francisco Arenas1 1Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, 4050-123 Porto, Portugal 2Department of Ecology and Animal Biology, University of Vigo, 36310 Vigo, Spain *Corresponding author: ifrodil@gmail.com ABSTRACT: The ecological role of wrack as a habitat-forming species for beach macrofauna was investigated by experimental manipulation of 2 macroalgal species: Laminaria ochroleuca Bachelot de la Pylaie, 1824, and Sargassum muticum (Yendo) Fensholt. Both species are abundant in rocky bed communities, and commonly found shaping wrack patches on Atlantic sandy beaches in NW Spain. In beach ecosystems, this resource subsidy provides macroinvertebrates with accessible food, refuge and nursery in an otherwise inhospitable environment. Our analysis indicated a substantial shift in the dominant macrofauna, from wrack-dependent consumers in L. ochroleuca patches to terrestrial larval species in S. muticum patches. In addition, we examined in situ for the first time the direct impacts of changes in ambient solar radiation on the macroalgal biochemical content, and the consequent effects on wrack-associated macrofauna. During a 5 d experiment, cut-off filters were applied to generate treatments: P: photosynthetically active radiation (PAR) (400-700 nm), PA: PAR + UVA (320-700 nm), PAB (procedural control): PAR + UVA + UVB (280-700 nm), and C: control with no filter. Lack of natural radiation affected the biochemical content of the wrack and promoted differences in the associated macrofaunal composition; taxa assemblages among wrack patches exposed to C and PAB treatments were more similar compared to P or PA exposed patches. Our results indicated that changes in wrack nutritional quality and phenols caused by a moderate manipulation of the UVR had consequent effects on beach macrofauna looking for shelter, food or both. We suggest that in a scenario of global impacts, changes in the identity and fundamental biochemical traits of wrack can affect beach macrofaunal assemblages with unpredictable implications for coastal food-webs and ecosystem functioning. KEY WORDS: Cut-off filters · Macrofaunal assemblages · Sandy beaches · Solar radiation · Wrack · Laminaria ochroleuca · Sargassum muticum Full text in pdf format Supplementary material PreviousNextCite this article as: Rodil IF, Olabarria C, Lastra M, Arenas F (2015) Combined effects of wrack identity and solar radiation on associated beach macrofaunal assemblages. Mar Ecol Prog Ser 531:167-178. https://doi.org/10.3354/meps11304 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 531. Online publication date: July 02, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Determinacion y evaluacion de los componentes presentes en las pinturas anti incrustantes utilizadas en la acuicultura y sus posibles efectos en sedimentos marinos del sur de Chile

Sediment samples were taken in three areas related to the use of antifouling paints in salmon farming in southern Chile, in order to detect changes in the abundance and diversity of benthic macrofauna due to the accumulation of metals such as Cu and Zn in sediments. The results show that if there especially Cu accumulation in sediments adjacent to cages each crop, but there were no significant changes in the composition or abundance of benthic macrofauna that accompanies these farms, even when concentrations Cu exceeded 800 µg g -1 in sediments.

Macrobenthic assemblages, sediment characteristics and heavy metal concentrations in soft-bottom Ebre Delta bays (NW Mediterranean)

The spatial distribution of soft-bottom macrofaunal assemblages and their relationship with sediment characteristics were examined in two semi-enclosed shallow-water bays (Alfacs Bay and Fangar Bay) in the Ebre Delta (Catalonia, NW Mediterranean) during 2006 and 2011. Three assemblages were identified: group 1, present in sediments that contain a high percentage of silt-clay, small median particle size and high organic matter content and located at the most external areas of both bays and in the central basin of Alfacs Bay; group 2, present in the shallow northern platform in Alfacs Bay and in both platforms in Fangar Bay, the locations which feature highly variable sediment characteristics; and group 3, present in the shallow areas of both bays, which are characterised by low silt-clay and organic matter content. In Alfacs Bay, the differentiation of these assemblages has persisted since 1987, independently of the increase in organic matter content and heavy metal concentrations and of the shift in macrofaunal composition that have occurred over the past 20years, most likely the result of increased agricultural activity.

Studies on the Mangrove Macro Faunal Diversity and Assessment among Different Sites in Port Blair Bay, South Andaman Islands

The mangrove intertidal zone is characterised by plenty floral and faunal diversity. The mangroves provide important habitat for a wide range of species like diverse communities of benthic organisms and function as nursery habitats for different types of crab, prawn and fish species and support offshore fish populations and fisheries. To assess the occurrence, spatial distribution and species composition of macro fauna in a mangrove area, core samples were taken along with transect in Portblair bay, South Andaman Islands. Three sites were taken; each study area was divided into three zones viz. Proximal, middle and distal zones, which were analyzed according to the floral composition. The highest value was observed at Barmanallah (2061 no.m-2), followed by Carbyn’s Cove (1710 no.m-2) and the lowest value was noticed at Manjery (882 no.m-2). Terebralia palustris, Cerithidea sp., Periopthalmus sp., Uca sp., Balanus sp. and Polychaetes were dominated in order. Some locations were found to support a high diversity of organisms across habitats, while other locations had high densities of a few species only.

Macrofauna do solo em uma cronosequência de capoeiras, florestas e pastos no Centro de Endemismo Belém, Amazônia Oriental

O Centro de Endemismo Belém (CEB) -região biogeográfica localizada entre os rios Tocantins e Pindaré- é a área mais desmatada da Amazônia. Estudar a biota do solo dos remanescentes florestais e de áreas em regeneração (capoeiras) do CEB é fundamental para promover práticas agrícolas mais sustentáveis e orientar ações de restauração de áreas degradadas. Dessa forma, o objetivo desse estudo foi identificar os principais determinantes da composição e da diversidade dos grandes táxons de macrofauna do solo (uso atual do solo, núcleos geográficos, histórico de uso, freqüência de fogo) em uma cronoseqüência de capoeiras e florestas no CEB. A macrofauna foi amostrada em oito áreas de capoeiras baixas (4-7 anos), seis áreas de capoeiras médias (11-15 anos), sete áreas de capoeiras altas (20-40 anos), oito áreas de remanescentes de florestas e três áreas de pastagem. Sua composição e diversidade foi estudada através de Análises de Componentes Principais e Entre-classes. Um total de 9.225 indivíduos pertencentes a 29 grandes taxóns (ordens ou famílias) foram coletados nas 32 parcelas amostradas. A composição da macrofauna se mostrou sensível ao efeito do histórico de uso do solo e identificou comunidades significativamente distintas entre as micro-regiões, havendo nessa escala efeito da cronosequência de capoeiras e florestas. A intensidade do uso do solo levou a redução da abundância e da riqueza de predadores, indicando alterações significativas no funcionamento do solo. Esses resultados mostram um efeito duradouro da degradação sobre a macrofauna do solo e conseqüentemente sobre suas funções ecológicas.

Abyssal macrofauna of the Kuril–Kamchatka Trench area (Northwest Pacific) collected by means of a camera–epibenthic sledge

Abyssal macrofaunal composition of 21 epibenthic sledge hauls from twelve stations taken in the Kuril–Kamchatka Trench (KKT) and at the adjacent abyssal plain, Northwest Pacific, is presented. Sampling with the fine meshed epibenthic sledge yielded higher abundances and species richness than was reported from previous expeditions from board of RV Vityaz. In total 84,651 invertebrates were sampled with RV Sonne between July and September of 2012 (31,854 invertebrates if standardised for 1000m2 trawled distances) from 41 taxa of different taxonomic ranks (15 phyla, 28 classes, 7 orders) were sampled from a trawled area of 53,708m² and have been analyzed. Few taxa were frequent and most taxa were rare in the samples, twelve taxa occurred with more than 1% frequency. Of these, the Polychaeta were most abundant followed by the benthic Copepoda and Isopoda. Total numbers of individuals varied between stations and were highest with 4238 individuals at station 2-10 close to the KKT in 4865m depth and lowest with 374 individuals at station 6-11 in 5305m depth. At this station also the lowest number of taxa occurred (18 taxa) while the highest number occurred with 31 taxa at station 3-9 in 4991m depth. Numbers of individuals decreased with increasing depth between 4830 and 5780m. Crustaceans of the superorder Peracarida were one of the dominating taxa with four orders occurring frequently in most samples. In total, Isopoda were most important and occurred with 59% of all peracarid orders sampled, followed by Amphipoda with 21%, Tanaidacea with 11%, Cumacea with 9%, and Mysidacea with <1%. The communities of the stations (and hauls) of the KKT abyssal area differ in terms of taxon composition from each other. A cluster analysis (nMDS) performed for all sampled stations revealed no clear pattern of community similarity between stations or hauls. All hauls close to the trench (2-9 and 2-10 close to the eastern slope of the KKT; and 3-9 and 4-3 at the western slope) were most different to the other hauls. Hauls 8-9 and 8-12 as well as 5-10 and 7-10 in the approximate centre of the overall research area were most similar (88% similarity). The non-isolated KKT area is characterized by higher abundances and higher benthic species richness than the geographically isolated and young deep-sea basin of the Sea of Japan.

Spatiotemporal changes in surface sediment characteristics and benthic macrofauna composition off the Rhône River in relation to its hydrological regime

The consequences of changes in the water flow of the Rhône River on surface sediment characteristics and benthic macrofauna composition were assessed within 3 distinct areas: (1) the delta front, (2) the prodelta, and (3) the distal zone. Five stations were sampled during or closely after: (1) an oceanic flood (April 2007), (2) a generalized flood (May 2008), (3) a Cevenol flood (December 2008), and (4) a dry period (July 2011). Measurements of sediment characteristics included granulometry (D0.5), bulk descriptors of sedimentary organics (OC, TN and THAA), descriptors of labile components of sedimentary organics (chloropigments, EHAA), and both descriptors of origin (Chl-b/Chl-a, C/N) and lability (Chl-a/(Chl-a+Phaeo-a), EHAA/THAA) of sedimentary organics. Sediment Profile Images were collected during April 2007, May 2008 and July 2011. Temporal changes in both sedimentary organics and benthic macrofauna were more important in the delta front and the prodelta than in the distal zone. Bulk characteristics of sedimentary organics presented decreasing inshore/offshore gradients during both April 2007 and July 2011 but not during May and December 2008. There were significant temporal changes in EHAA/THAA at all stations. Changes in benthic macrofauna composition differed between: (1) the delta front and the prodelta, and (2) the distal zone. In the former area, the dry period was associated with establishing a mature community characterized by high abundances and species richness. The best description of spatiotemporal changes in benthic macrofauna composition by surface sediment characteristics was obtained using D0.5, Chl-b/Chl-a, Chl-a/(Chl-a+Phaeo-a) and EHAA, which supports the role of the quality of sedimentary organics in controlling benthic macrofauna composition.

Biodiversity and community composition of sediment macrofauna associated with deep-sea Lophelia pertusa habitats in the Gulf of Mexico

Scleractinian corals create three-dimensional reefs that provide sheltered refuges, facilitate sediment accumulation, and enhance colonization of encrusting fauna. While heterogeneous coral habitats can harbor high levels of biodiversity, their effect on the community composition within nearby sediments remains unclear, particularly in the deep sea. Sediment macrofauna from deep-sea coral habitats (Lophelia pertusa) and non-coral, background sediments were examined at three sites in the northern Gulf of Mexico (VK826, VK906, MC751, 350–500m depth) to determine whether macrofaunal abundance, diversity, and community composition near corals differed from background soft-sediments. Macrofaunal densities ranged from 26 to 125 individuals 32cm−2 and were significantly greater near coral versus background sediments only at VK826. Of the 86 benthic invertebrate taxa identified, 16 were exclusive to near-coral habitats, while 14 were found only in background sediments. Diversity (Fisher’s α) and evenness were significantly higher within near-coral sediments only at MC751 while taxon richness was similar among all habitats. Community composition was significantly different both between near-coral and background sediments and among the three primary sites. Polychaetes numerically dominated all samples, accounting for up to 70% of the total individuals near coral, whereas peracarid crustaceans were proportionally more abundant in background sediments (18%) than in those near coral (10%). The reef effect differed among sites, with community patterns potentially influenced by the size of reef habitat. Taxon turnover occurred with distance from the reef, suggesting that reef extent may represent an important factor in structuring sediment communities near L. pertusa. Polychaete communities in both habitats differed from other Gulf of Mexico (GOM) soft sediments based on data from previous studies, and we hypothesize that local environmental conditions found near L. pertusa may influence the macrofaunal community structure beyond the edges of the reef. This study represents the first assessment of L. pertusa-associated sediment communities in the GOM and provides baseline data that can help define the role of transition zones, from deep reefs to soft sediments, in shaping macrofaunal community structure and maintaining biodiversity; this information can help guide future conservation and management activities.

Towards a suitable ecological status assessment of highly stratified mediterranean estuaries: A comparison of benthic invertebrate fauna indices

Biotic indices developed to assess the ecological status of coastal waters according to the European Water Framework Directive (WFD) often show discrepancies when they are applied in transitional environments. Although several indices have been widely used in transitional waters throughout Europe, there is still a lack of knowledge about their suitability assessing ecological status. We evaluated the performance of most common used biotic indices and community parameters (e.g. Multivariate AZTI's Marine Biotic Index (M-AMBI), BENTIX, Benthic Opportunistic Polychaetes Amphipods index (BOPA), diversity indices, species richness, abundance) that have been proposed in the scope of WFD, using data of macroinvertebrate community coming from a special case of transitional water body, the highly stratified Ebro estuary. Additionally, we tested their ability to respond to the main pressures affecting the Ebro estuary, the hydrological alteration due to regulation and the pollution pressure due to nutrient enrichment. Estimation of hydrological alteration was based on flow historical data (period from 1913 to 1963), that we assumed as 'hydrological reference conditions' for Ebro estuary. Pollution pressure was estimated by means of PCA analysis including organic and nutrient enrichment related variables, expressed as a synthetic index by PCA factor scores extraction. All the community parameters were able to detect changes in macrofauna composition along the estuarine gradients and were able to differentiate between the impoverished stations and the healthier ones. Regarding indices, the ratings were contradictory and only M-AMBI classified the stations in the correct way. Strong significant correlations were found between indices and metrics and the calculated pressures; nevertheless, these correlations showed a paradoxical result, since increasing hydrological alteration benefited the macrofauna, achieving great complexity. Other identified limitations of biotic indices were the opposite classifications, overestimation of ecological status and low resolution ability. We conclude that for transitional water ecosystems, where each water body has particular characteristics, is difficult the use of 'common biological' assessment tools as the results of this study, among others (more details in discussion section), have demonstrated. Nevertheless, M-AMBI seemed to work in the correct way, so further investigation about its use for transitional waters is necessary. The development of new strategies such as the use of historical data, the use of metrics as a complement for the assessment could be a reliable alternative.

Species Composition of the Benthic Macroinvertebrates on the Coastline Vegetated Rocky Substrates of the Southern Caspian Sea

Abstract For studying benthic macrofaunal composition associated with seagrass rocky beds of the southern Caspian Sea, two time samplings were carried out along the coast line in the winter and summer of 2013. In total, 1,286 specimens of the five species were identified: Pontogammarus maeoticus, Balanus improvisus, Mytilaster lineatus, Palaemon elegans and Alitta succinea. The total recorded abundance was 5,675 and 755 ind./m2, with a biomass of 147,271 and 31,238 mg/m2 in the winter and summer respectively. The collected species in this study are generally non-indigenous (except P. maeoticus) and could potentially have an effect on native benthic fauna, as an additional food source could facilitate the commercially exploited fish stocks. Thus further studies are required to monitor their potential interactions on the Caspian Sea fauna

Macroinfauna Dynamics and Sediment Parameters of a Subtropical Estuarine Lake—Coombabah Lake (Southern Moreton Bay, Australia)

Dunn, R.J.K.; Lemckert, C.J.; Teasdale, P.R., and Welsh, D.T., 2013. Macroinfauna dynamics and sediment parameters of a subtropical estuarine lake—Coombabah Lake (Southern Moreton Bay, Australia).The distribution, composition, density, and biomass of benthic macrofauna within estuarine environments typically exhibit significant variations attributable to heterogeneity in and interactions between physical, biological, and chemical processes. The spatial and temporal dynamics of benthic macroinfauna assemblages and physicochemical sediment parameters within the intertidal mudflats of a subtropical estuarine lake (Coombabah Lake, Southern Moreton Bay) were studied at four sites from August 2006 to April 2007. No significant seasonal changes were observed at any site for all physical sediment parameters. The northern sample sites were characterised by fine- to medium-grained to moderately to poorly sorted sediments and the southern sample sites by fine-grained to moderately well to well-sorted. A total of 1029 individuals representing species from three orders, including deposit feeding and filter feeding macroinfaunal groups, were collected. The highest combined species densities occurred in the fine-grained southern sites, with the greatest combined species density occurring at Site 4 during winter. Amphipods (Victoriopisa australiensis) and polychaete worms (Simplisetia aequisetis) dominated the lake-wide faunal community with V. australiensis, representing 49% of the total retrieved macroinfauna. Significant correlations between mean macroinfauna densities, biomassDW, sediment parameters, and seasonal maximum monthly temperatures were identified during the study. Seasonal trends in combined site densities were observed at each of the lake sites, with the highest combined density occurring during winter. Spatial and temporal variations might also be partially explained by the predation pressures of fish and migratory wading birds within the lake, with the seasonal presence of migratory wading birds coinciding with the minimum observed macroinfauna densities at each sample site.