Habitat Characterization Research Articles

Habitat selection by green turtles in a spatially heterogeneous benthic landscape in Dry Tortugas National Park, Florida

We examined habitat selection by green turtles Chelonia mydas at Dry Tortugas National Park, Florida, USA. We tracked 15 turtles (6 females and 9 males) using platform trans- mitter terminals (PTTs); 13 of these turtles were equipped with additional acoustic transmitters. Location data by PTTs comprised periods of 40 to 226 d in varying months from 2009 to 2012. Core areas were concentrated in shallow water (mean bathymetry depth of 7.7 m) with a comparably dense coverage of seagrass; however, the utilization distribution overlap index indicated a low degree of habitat sharing. The probability of detecting a turtle on an acoustic receiver was inversely associated with the distance from the receiver to turtle capture sites and was lower in shallower water. The estimated daily detection probability of a single turtle at a given acoustic sta- tion throughout the acoustic array was small (<0.1 in any year), and that of multiple turtle detec- tions was even smaller. However, the conditional probability of multiple turtle detections, given at least one turtle de tection at a receiver, was much higher despite the small number of tagged tur- tles in each year (n = 1 to 5). Also, multiple detections of different turtles at a receiver frequently occurred within a few minutes (40%, or 164 of 415, occurred within 1 min). Our numerical esti- mates of core area overlap, co-occupancy probabilities, and habitat characterization for green turtles could be used to guide conservation of the area to sustain the population of this species.

Fishing Areas Characterization: a demonstrative case of the SIMOcean platform

Fishing Areas Characterization: a demonstrative case of the SIMOcean platform

Distribution and Habitat Associations of California Black Rail (Laterallus jamaicensis coturniculus) in the Sacramento–San Joaquin Delta

Author(s): Tsao, Danika C.; Melcer, Jr., Ronald E.; Bradbury, Michael | Abstract: Past studies documenting the distribution and status of state “Threatened California black rail (Laterallus jamaicensis coturniculus; hereafter black rail) have largely omitted the Sacramento—San Joaquin Delta (hereafter Delta). During March to May of 2009–2011, we conducted call–playback surveys to assess the status of the species within a wide range of wetland habitats of the central Delta region. We detected black rails at 21 of 107 discrete wetland sites, primarily on in-channel islands with dense cover. To better understand the habitat and land cover characteristics, we developed a model of habitat suitability from these occurrence data and a fine-scale vegetation and land use dataset using MaxEnt. We also evaluated differences in the size of wetlands at sites where black rails were detected versus where they were not. Through surveys and quantitative modeling, we found black rail presence differed from other regions within California and Arizona, in that it was positively associated with tall (1 to 5 m) emergent vegetation interspersed with riparian shrubs. Specific plants correlated with black rail presence included emergent wetland (Bolboschoenus acutus, B. californicus, B. acutus, Typha angustifolia, T. latifolia, Phragmites australis) and riparian (Salix exigua, S. lasiolepis, Rosa californica, Rubus discolor, Cornus sericea) species. Median patch size was significantly larger and perimeter-to-area ratios were significantly lower at wetland sites where black rails were found. These results provide a preliminary characterization of black rail habitat in the Delta region and highlight the need for better understanding of this listed species’ population size and habitat use in the region, in light of anticipated climate change effects and proposed large-scale restoration in the Delta.

Larval habitat characterization of Anopheles darlingi from its northernmost geographical distribution in Chiapas, Mexico.

BackgroundAnopheles darlingi is considered the most efficient malaria vector in the Neotropical region. In Mexico, its role as an incriminated vector of Plasmodium has not been confirmed in the Lacandon forest. Similarly, knowledge about bionomic and larval ecology is scarce. The study aim was to identify and describe the larval habitats of An. darlingi in Chiapas, México.MethodsStandard larval collections were performed in the Lacandon forest region and in the Soconusco region of southern Chiapas from January 2010 to April 2014, including dry and rainy seasons. Mean larval density of An. darlingi was estimated according to hydrological types, and associations between the presence of An. darlingi and environmental factors including ecological parameters and geographic positions were statistically analysed.ResultsOne hundred and twelve aquatic habitats were analysed, 80 from the Lacandon forest region and 32 from the Soconusco region; 94.64 % of these sites presented anopheline larvae. In total, 10,977 larvae belonging to 11 Anopheles species were collected. The 19 (out of 112) larval habitats positive to An. darlingi were: rain puddles (26.32 %), ground pools (21.05 %), ponds (15.79 %), ditches (15.79 %), river margins (10.53 %) and streams (10.53 %). Overall, the average (±SD) larval density was 6.60 ± 2.41 larvae per dip. Multiple logistic regression analysis showed that temporary habitats, green algae presence and stagnant water were associated with An. darlingi larval presence. The positive habitats were found in the Lacandon forest region during the rainy season (May–September). No specimens were found in the Soconusco region of the coastal plain of Chiapas.ConclusionThe mosquito An. darlingi larval habitats were found in different hydrological types. The habitat stability, presence of algae and water current were the main factors for An. darlingi larval occurrence. The information on the characteristics of the larval habitats of An. darlingi will be useful in sustainable programmes for malaria control in the Lacandon forest region, Chiapas.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-1037-0) contains supplementary material, which is available to authorized users.

Satellite-based remote sensing of running water habitats at large riverscape scales: Tools to analyze habitat heterogeneity for river ecosystem management

We illustrate an approach to quantify patterns in hydraulic habitat composition and local heterogeneity applicable at low cost over very large river extents, with selectable reach window scales. Ongoing developments in remote sensing and geographical information science massively improve efficiencies in analyzing earth surface features. With the development of new satellite sensors and drone platforms and with the lowered cost of high resolution multispectral imagery, fluvial geomorphology is experiencing a revolution in mapping streams at high resolution. Exploiting the power of aerial or satellite imagery is particularly useful in a riverscape research framework (Fausch et al., 2002), where high resolution sampling of fluvial features and very large coverage extents are needed. This study presents a satellite remote sensing method that requires very limited field calibration data to estimate over various scales ranging from 1m to many tens or river kilometers (i) spatial composition metrics for key hydraulic mesohabitat types and (ii) reach-scale wetted habitat heterogeneity indices such as the hydromorphological index of diversity (HMID). When the purpose is hydraulic habitat characterization applied over long river networks, the proposed method (although less accurate) is much less computationally expensive and less data demanding than two dimensional computational fluid dynamics (CFD). Here, we illustrate the tools based on a Worldview 2 satellite image of the Kiamika River, near Mont Laurier, Quebec, Canada, specifically over a 17-km river reach below the Kiamika dam. In the first step, a high resolution water depth (D) map is produced from a spectral band ratio (calculated from the multispectral image), calibrated with limited field measurements. Next, based only on known river discharge and estimated cross section depths at time of image capture, empirical-based pseudo-2D hydraulic rules are used to rapidly generate a two-dimensional map of flow velocity (V) over the 17-km Kiamika reach. The joint distribution of D and V variables over wetted zones then is used to reveal structural patterns in hydraulic habitat availability at patch, reach, and segment scales. Here we analyze 156 bivariate (D, V) density function plots estimated over moving reach windows along the satellite scene extent to extract 14 physical habitat metrics (such as river width, mean and modal depths and velocity, variances and covariance in D and V over 1-m pixels, HMID, entropy). A principal component analysis on the set of metrics is then used to cluster river reaches in regard to similarity in their hydraulic habitat composition and heterogeneity. Applications of this approach can include (i) specific fish habitat detection at riverscape scales (e.g., large areas of riffle spawning beds, deeper pools) for regional management, (ii) studying how river habitat heterogeneity is correlated to fish distribution and (iii) guidance for site location for restoration of key habitats or for post regulation monitoring of representative reaches of various types.

&lt;b&gt;Habitat structure determining the spatial distribution of ichthyofauna in a Brazilian stream

This work aimed to evaluate the relationship between parameters of fish communities and the habitat structure of a stream. Twenty three stretches six meters long were evaluated in the Samambaia stream located inside the Sumidouro Park, Rio das Velhas basin, state of Minas Gerais, Brazil. Fish samplings and habitat characterization were made for each stretch. Seven variables of habitat (vegetal cover, width, depth, substrate, flow, presence of aquatic plants and leaf litter) and two variables characterizing the longitudinal gradient (altitude and distance from the Sumidouro lagoon) were assessed. The fish community responded to habitat changes, presenting variation in richness and composition of species. Richness was positively influenced by the presence of leaf litter and aquatic plants. Furthermore, through similarity data (NMDS) and habitat structure (PCA), it was possible to observe the separation of the 23 stretches into two groups with a dissimilarity of approximately 90%. We concluded that the variation in richness and composition of species throughout the stream was strongly related to the variables of habitat structure. This variation is clearer when considering the longitudinal gradient which highlights a great difference between stretches nearer and farther from the mouth of Samambaia stream.

Spatial scale and geographic context in benthic habitat mapping: review and future directions

Understanding the effects of scale is essential to the understanding of natural eco - systems, particularly in marine environments where sampling is more limited and sporadic than in terrestrial environments. Despite its recognized importance, scale is rarely considered in benthic habitat mapping studies. Lack of explicit statement of scale in the literature is an impediment to better characterization of seafloor pattern and process. This review paper highlights the impor- tance of incorporating ecological scaling and geographical theories in benthic habitat mapping. It reviews notions of ecological scale and benthic habitat mapping, in addition to the way spatial scale influences patterns and processes in benthic habitats. We address how scale is represented in geographic data, how it influences their analysis, and consequently how it influences our under- standing of seafloor ecosystems. We conclude that quantification of ecological processes at multi- ple scales using spatial statistics is needed to gain a better characterization of specieshabitat relationships. We offer recommendations on more effective practices in benthic habitat mapping, including sampling that covers multiple spatial scales and that includes as many environmental variables as possible, adopting continuum-based habitat characterization approaches, using statistical analyses that consider the spatial nature of data, and explicit statement of the scale at which the research was conducted. We recommend a set of improved standards for defining benthic habitat. With these standards benthic habitats can be defined as 'areas of seabed that are (geo)statistically significantly different from their surroundings in terms of physical, chemical and biological characteristics, when observed at particular spatial and temporal scales'.

Remote sensing and habitat mapping for bearded capuchin monkeys (Sapajus libidinosus): landscapes for the use of stone tools

Application of remote sensing and geographic information systems to the characterization of wildlife habitats is an area of growing significance for conservation. We examine the use of space of a group of bearded capuchin monkeys, a species unique in their use of stone tools to extract encapsulated foods. We define important landscape variables associated with the monkeys’ behavior, especially the use of stone tools. Maximum entropy modeling is used to define the landscape characteristics associated with the monkeys’ use of space. The variables evaluated in model building include normalized difference vegetation index, distance to roads, distance to areas of human influence, distance to vertical scarps, elevation, land cover/land use class, and percentages of green vegetation, bare soil, and shadow from spectral mixture analysis. Distance to areas of human influence and distance to vertical scarps were the variables most closely associated with capuchin habitat suitability (permutation importance 31.7% and 21%, respectively). Stone tool use occurred in areas of lower elevation and higher percent green vegetation relative to other behavior. These results may inform efforts for conserving the unique stone tool use of this species, especially relevant due to the recent expansion and intensification of industrial agriculture in the region.

Characterization of a Romanian saline habitat – Resources for obtaining biofertilizers to increase salt tolerance of cultivated plants

Characterization of a Romanian saline habitat – Resources for obtaining biofertilizers to increase salt tolerance of cultivated plants

Assessing Avian Richness and Diversity in Different Regions of Oil Palm Plantation in Selangor, Malaysia

Malaysia is characterized by a variety of habitats such as forests, clearings, thickets, and cropland that attract various species of birds. This study examined the bird community in terms of richness and diversity at oil palm plantations habitat. The abundance of birds was determined by using distance sampling point count method. A total of 2722 birds belonging to 38 families representing 86 species of birds were detected. Diversity analysis indicates that the species of birds in the oil palm plantation at Sungai Pelek is more diverse (Shannon-Wiener Diversity Index H; 3.52) and richness (Margalef’s Richness Index R1; 10.2) than oil palm plantation in Teluk Panglima Garang-Pulau Carey and Banting-Jenjarum. However, the species of birds in the oil palm plantations at Teluk Panglima Garang-Pulau Carey and Banting-Jenjarum show higher evenness (Pielou’s Evenness Index E; 0.82) compared with oil palm plantations in Sungai Pelek. The results of this study indicate that the species composition and distribution of the avian species in the oil palm plantations are affected by habitat characterization of that particular area and its vicinity.

Habitat characterization of a tidal energy site using an ROV: Overcoming difficulties in a harsh environment

The Snohomish County Public Utility District (Snohomish) in Washington State USA has undertaken a tidal turbine site investigation at Admiralty Head, the entrance into the Puget Sound, to determine the feasibility of installing two energy conversion plants that will supply electrical power to the local grid. This site is close to shore and to major metropolitan areas that can benefit from this cleanly generated power. Large tidal exchanges take place at this site and can provide predictable and sustainable tidal energy. As part of the permitting process Snohomish has undertaken a seafloor investigation to determine the habitat characteristics of the seafloor and inform the appropriate location for the turbines' placement. In 2010, to assess habitat types multibeam echosounder (MBES) images were produced and ground-truth video surveys using an ROV were undertaken with the requirement that little disturbance occurs to the seafloor. Collection of these data was challenging as the highly dynamic oceanographic and geologic (tectonic) environment made it difficult to undertake in situ observations of the seafloor. Strong tidal currents, even during predicted slack tides, forced new thinking on how data should be collected in order to evaluate the seafloor substrate, habitats and ecology in light that a statistically methodology could not be accomplished, or if indeed a statistical analysis was necessary at all. Additional information on tidal currents has been gathered since these surveys, which should aid in the future collection of data, although the underlying questions about the possibility of, and need for, a statistical analysis remain. Extensive video assessment was needed to produce a map that could exhibit habitat types. This was attempted by focusing on the geology of the seafloor and selecting common organisms, such as sessile and encrusting fauna (e.g., sea anemones, barnacle fields, crinoids) and epifauna (e.g., sea stars) to relate to substrate types. Heavily encrusted and lightly encrusted substrates were mapped to show areas where sediment is presently being transported through the area. ROV line- or timed-transects to count biota appears not to be necessary to obtain information needed to validate marine benthic habitat types. Rather, general observational transects and more stabilized in situ observational stations used for close examination of the biota and measurement of the substrate is recommended

Assessing Avian Richness and Diversity in Different Regions of Oil Palm Plantation in Selangor, Malaysia

Malaysia is characterized by a variety of habitats such as forests, clearings, thickets, and cropland that attract various species of birds. This study examined the bird community in terms of richness and diversity at oil palm plantations habitat. The abundance of birds was determined by using distance sampling point count method. A total of 2722 birds belonging to 38 families representing 86 species of birds were detected. Diversity analysis indicates that the species of birds in the oil palm plantation at Sungai Pelek is more diverse (Shannon-Wiener Diversity Index H; 3.52) and richness (Margalef’s Richness Index R1; 10.2) than oil palm plantation in Teluk Panglima Garang-Pulau Carey and Banting-Jenjarum. However, the species of birds in the oil palm plantations at Teluk Panglima Garang-Pulau Carey and Banting-Jenjarum show higher evenness (Pielou’s Evenness Index E; 0.82) compared with oil palm plantations in Sungai Pelek. The results of this study indicate that the species composition and distribution of the avian species in the oil palm plantations are affected by habitat characterization of that particular area and its vicinity.

An assessment of river habitat quality as an indicator of conservation status. A case study in the Northwest of Spain

There are several methodologies for the characterization and evaluation of river habitats. The scientific community has made a great effort in designing the best indexes for this purpose, and they have also been tested in different countries and rivers. Nevertheless, there has not been a transfer of that knowledge to land managers of these spaces or, at least, to those who design improvement and restoration measures. The aim of our research was the assessment of the Riparian Forest Quality Index (QBR), the “Riparian Quality Index” (RQI) and the “Fluvial Habitat Index” (IHF) as indicators of the ecological status of fluvial habitats and their application in restoration projects. The main results of this study were that the IHF index could be used as a support resource and as a monitoring tool to assess the habitat heterogeneity before and after any action is taken. However, when we evaluated the QBR and RQI indexes, the best results were with the first one. The total QBR suggests the urgency level of restoration in the section that is evaluated, and each of its sub-indexes identifies which element of the river is affected. Therefore, it will be a useful tool in decision making for the conservation of these characteristic spaces, especially for engineers who, as a result of their experience in biological and ecological processes, are involved in the design and building of ecosystems, particularly in rivers and on their banks.

Sedimentary facies, geomorphic features and habitat distribution at the Hudson Canyon head from AUV multibeam data

Mapping of physical benthic habitats at the head of Hudson Canyon was performed by means of integrated analysis of acoustic data, video surveys and seafloor sampling. Acoustic mapping, performed using AUV-mounted multibeam sonar, provided ultra-high resolution bathymetric and backscatter imagery for the identification of geomorphological features and the characterization of surficial sediments. Habitat characterization in terms of seafloor texture and identification of benthic and demersal communities was accomplished by visual analysis of still photographs from underwater vehicles. Habitat classes were defined on the basis of the seafloor texture observed on photos and then compared with the geophysical data in order to associate habitats to acoustic classes and/or geomorphological features. This enabled us to infer habitat distribution on the basis of morpho-acoustic classes and extrapolate results over larger areas. Results from bottom trawling were used to determine the overall biodiversity within the identified habitats. Our analysis revealed a variety of topographic and sedimentological structures that provide a wide range of physical habitats. A variety of sandy and muddy substrates, gravel patches and mudstone outcrops host rich and varied faunal assemblages, including cold-water corals and sponge communities. Pockmark fields below 300m depth suggest that methane-based chemosynthetic carbonate deposition may contributes to creation of specific benthic habitats. Hummocky terrain has been delineated along the canyon rims and associated with extensive, long-term burrowing activity by golden tilefish (Lopholatilus chamaeleonticeps). These results show the relationships of physical features to benthic habitat variation, support the notion of the area as a biodiversity hotspot and define essential habitats for planning of sustainable regional fisheries.

Let the concept of indicator species be functional!

AbstractAimsThe identification of diagnostic or indicator species with high fidelity to a given group of sites is an important step for the ecological characterization of habitats or community types. The determination of the degree of fidelity to a target group is traditionally performed by analysing the concentration of species occurrences or abundances in different groups of sites. Surprisingly, although one of the main purposes of indicator species analysis is to give ecological meaning to groups of sites, none of the methods proposed to date take into account the functional ecology of diagnostic species. Therefore, the question we address here is: can we use functional traits of species to improve the diagnostic value of indicator species?LocationSand dune communities in central Italy.MethodsIn this paper we propose a two‐step procedure for incorporating the functional traits of a given species in the evaluation of its diagnostic value. For a given set of plots that are classified into different groups, first the indicator species that best characterize each group of plots are identified with the usual statistical tools based on species occurrences. Next, the functional association between the indicator species and the target groups of plots is tested by measuring the functional distance between the indicator species and the centroids of all plots in the target group. A species is positively associated with a group if its mean functional distance from all plot centroids in the group is significantly lower than expected.ResultsIn this example, we show that the functional association of the indicator species with a given habitat type is represented by less species than the association highlighted solely through species occurrences and/or abundances. This subset of species appears to better characterize the functional ecology of coastal dune plant assemblages and shows a higher diagnostic value in comparison with those obtained through the traditional indicator analysis.ConclusionsAs functional traits are the main ecological attributes by which different species influence ecosystem processes, we believe that the methodology proposed here provides a relevant tool for ecological applications as distinct as vegetation science, conservation biology or landscape management.

The physicochemical and environmental factors affecting the distribution of Anopheles merus along the Kenyan coast.

BackgroundMembers of the Anopheles gambiae complex are the main transmitters of malaria. Anopheles merus is a member of the complex found along the Kenyan coast because it breeds in saline waters. An entomological study was conducted in Garithe Malindi District, to investigate the physicochemical and environmental factors affecting the distribution of An. merus.MethodsField and laboratory studies were used to investigate the breeding habitats of the subspecies. Mosquito larvae were sampled using standard dipping technique from small pockets of pools, ponds, hoof prints, road drain, wells and mangrove swamps found in Garithe. All 3rd and 4th instars of Anopheles larvae sampled were identified microscopically into species. A representative of Anopheles gambiae complex was then identified to specific sibling species using r-DNA PCR technique.The habitats were characterized based on temperature, conductivity, salinity, dissolved oxygen, total dissolved solids, pH, size, distance to nearest house, canopy coverage, surface debris, presence of algae, emergent plants, turbidity and habitat types.ResultsA total of 159 morphologically identified late stage instar Anopheles gambiae s.l larvae were selected for r-DNA analysis by PCR. Out of these, 60.4% (n = 96) were Anopheles merus, 8.8% (n = 14) were Anopheles arabiensis, 18.2% (n = 29) were Anopheles gambiae s.s and 12.6% (n = 20) were unknown.Using paired t-test (t (121) = −3.331, P = 0.001) a significantly high proportion of An. merus was observed in all habitats compared to An. arabiensis, and An. gambiae s. s.In habitat characterization, Pearson’s correlation analysis test showed different parameters being associated with the occurrence of An. merus larvae in the different habitats sampled. Six out of the 55 correlation coefficients (10.9%) were statistically significant, suggesting non-random association between some pairs of variables. Those that had a significantly high positive correlation with An. merus included temperature, salinity, conductivity, total dissolved solids and algae.ConclusionsDifferent physicochemical parameters and environmental parameters affect the occurrence of An. merus. In this study, higher temperatures accelerate the growth of the larvae and aids in growth of micro-organisms and algae which are food sources for the larvae. Saline waters favour the growth and development of An. merus larvae; they are also able to develop in a range of saline waters. Conductivity, total dissolved solids and canopy coverage are among the important factors influencing the development and abundance of An. merus larvae in their habitats. Habitat type also influences the abundance of An. merus larvae. They mainly prefer to breed in pools and ponds, but not swamps, hoof prints and wells.

Habitat characterization for striped marlin in the Pacific Ocean

Striped marlin (Kajikia audax) are highly valuable in commercial and recreational fisheries, and recently determined to be overfished in the Western and Central North Pacific Ocean, but direct field observations of their vertical habitats are lacking. To characterize their spatial and oceanographic associations across multiple regions in the Pacific (Australia, New Zealand, Hawaii, Southern California, Baja California, Costa Rica, Panama, and Ecuador), we analyzed behavioral data returned by 159 pop-up satellite archival tags (median, maximum deployment: 61; 259 days). Striped marlin demonstrated pronounced use of the mixed layer, with fish spending at least 54% of their time between 0 and 10m across all regions. Individuals remained near the surface in nighttime and were located near the bottom of the mixed layer during daytime. Although striped marlin shared a thermal niche >20°C and remained within ∼8°C of sea surface temperature (SST), even when 15–31°C SSTs were experienced, the deepest depth (532m) and coldest temperature (8.6°C) recorded to date indicated broader habitat associations. Vertical activity below the mixed layer comprised a lesser portion (5–45%) of their time at depth but suggests that key ecological functions occur there. We examined the effects of spatiotemporal and environmental factors on percent time spent at ≥60m and maximum depth through the use of generalized additive mixed models. Location, SST, mixed layer depth, temperature at 100m and dissolved oxygen at 100m and 300m were significant predictors of vertical activity. Striped marlin exploited cold (<15°C) or low oxygen (<3.5mlL−1) environments for short durations (10–40min), presumably for foraging and predator avoidance. Understanding vertical habitat characteristics of striped marlin is necessary for evaluating their vulnerability to gear, for identification of realistic bycatch reduction measures, and for providing spatially explicit information in stock assessments.

Preliminary data on habitat characterization relevance for red coral conservation and management

Through a non-invasive and interdisciplinary approach, distribution and size/age structure of deep dwelling populations of the precious red coral Corallium rubrum (LINNAEUS, 1758), were described in two different areas of the south Sardinia continental shelf: San Pietro Island and Capo Carbonara. Although its presence in south Sardinian waters is known, data on coral populations dwelling in deeper waters (below 50 meters of depth) are still represented by few studies. Data collected in the framework of the project MaGIC (Marine Geohazard along Italian Coasts), carried out in summer 2009 and spring 2010, furnished the guideline to map and identify rocky habitats (e.g. submarine canyons and outcrops) along the continental margin, which are suitable for red coral settlement. An extensive ROV survey, carried out in autumn 2011, provided useful information on occurrence, abundance, density and morphometric parameters of coral colonies. Red coral was found in both sites, distributed in patches, in different scenarios characterized by different habitat complexity. Over 1400 colonies were found in Capo Carbonara along the steep walls of a secondary channel of the Carbonara Canyon, while hundreds of specimens were found west of San Pietro Island along the outcrops ridges and on small boulders. Both populations were mainly composed by small and young colonies, while densities were different among sites, possibly affected by the role that habitat complexity plays in hydrodynamic and, consequently, on food supply, sedimentation, and settlement of colonies. These preliminary results contribute to advance knowledge on distribution and demography of deep dwelling populations of C.rubrum, which gain considerable importance in conservation and management of this precious resource. We strongly stress that interdisciplinary approaches that combines different scales of multibeam and ROV investigation are today fundamental to better understand distribution patterns within habitats, at species or community level.

Inter-epidemic abundance and distribution of potential mosquito vectors for Rift Valley fever virus in Ngorongoro district, Tanzania

BackgroundRift Valley fever (RVF) is a mosquito-borne viral zoonosis that primarily affects ruminants but also has the capacity to infect humans.ObjectiveTo determine the abundance and distribution of mosquito vectors in relation to their potential role in the virus transmission and maintenance in disease epidemic areas of Ngorongoro district in northern Tanzania.MethodsA cross-sectional entomological investigation was carried out before the suspected RVF outbreak in October 2012. Mosquitoes were sampled both outdoors and indoors using the Centre for Disease Control (CDC) light traps and Mosquito Magnets baited with attractants. Outdoor traps were placed in proximity with breeding sites and under canopy in banana plantations close to the sleeping places of animals.ResultsA total of 1,823 mosquitoes were collected, of which 87% (N=1,588) were Culex pipiens complex, 12% (N=226) Aedes aegypti, and 0.5% (N=9) Anopheles species. About two-thirds (67%; N=1,095) of C. pipiens complex and nearly 100% (N=225) of A. aegypti were trapped outdoors using Mosquito Magnets. All Anopheles species were trapped indoors using CDC light traps. There were variations in abundance of C. pipiens complex and A. aegypti among different ecological and vegetation habitats. Over three quarters (78%) of C. pipiens complex and most (85%) of the A. aegypti were trapped in banana and maize farms. Both C. pipiens complex and A. aegypti were more abundant in proximity with cattle and in semi-arid thorn bushes and lower Afro-montane. The highest number of mosquitoes was recorded in villages that were most affected during the RVF epidemic of 2007. Of the tested 150 pools of C. pipiens complex and 45 pools of A. aegypti, none was infected with RVF virus.ConclusionsThese results provide insights into unique habitat characterisation relating to mosquito abundances and distribution in RVF epidemic-prone areas of Ngorongoro district in northern Tanzania.

Oviposition Site Selection and Habitat Characterization of Anopheles Mosquito in Abraka, Delta State, Nigeria

Background: Malaria still remains a life - threatening disease worldwide causing between 190 and 311 million cases of malaria in 2008. Due to the ever increasing resistance to malaria drugs, source reduction has been recognized as a complementary approach to further reduce malaria transmission. Given that the availability of suitable habitats for the oviposition of anopheline mosquitoes increases their breeding and possibly malaria transmission. We p roposed that characterizing the breeding site of Anopheles is of major importance for the transition from malaria control to elimination in our study area. However, information on the oviposition sites, characteristics and influencing factors of breeding s ites of Anopheles mosquitoes is lacking. This study aimed to determine the preferential oviposition sites, breeding site characteristics and related environmental parameters. Methods: A study was undertaken in Abraka, Delta State to determine the preferent ial oviposition