Habitat Suitability Index Model Research Articles

Integrated Hydraulic Modelling, Water Quality Modelling and Habitat Assessment for Sustainable Water Management: A Case Study of the Anyang-Cheon Stream, Korea

Recent ecological stream restoration projects have focused on expanding the water-friendly space of streams, promoting the health of aquatic ecosystems, and restoring various habitats, which raise the need for relevant research. Applying integrated environmental analysis, this study quantifies the change in hydraulic characteristics before and after the restoration projects through physical habitat simulation and links the results of physical impacts to estimate benefits of increase in water quality and aquatic ecosystem health due to the implementation of the project. For this, the study area is a 3.3 km long reach of the Anyang-cheon Stream, Korea. Field monitoring revealed that five fish species are dominant and sub-dominant, and account for 76% of the total fish community. To assess the change of before and after ecological stream restoration project, the River2D and Coastal Modelling System (CMS)-Flow 2D models were used for hydraulic and water quality simulations, respectively. For the habitat simulation, the HSI (Habitat Suitability Index) model was used. In addition, the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) was used to calculate changes in water quality index and to examine changes in habitat areas with an integrated quantitative index, the methodology of Zingraff-Hamed et al. was adopted. It was found that the ecological stream restoration project significantly increased for the eco-friendly area. In addition, the changes in water quality and habitat suitability grades before the ecological river restoration project were improved to two stages and one stage, respectively. This study applied the integrated analytical framework as a policy/project assessment tool and the results of this study will be useful for the integrated water management policy.

Assessing habitat suitability and habitat fragmentation for endangered Siberian cranes in Poyang Lake region, China

Poyang Lake is located in the middle and lower reaches of the Yangtze River in China. It is the most important wintering area for the endangered Siberian cranes. Identifying the scale characteristics of habitat selection for Siberian cranes is essential for habitat conservation. In this study, a habitat suitability index (HSI) model based on multiscale habitat features was developed to assess the distribution and fragmentation degree of the suitable habitat for Siberian cranes before and after the construction of the proposed Poyang Lake Hydraulic Project (PLHP). The habitat of the entire lake area was divided into four ranks on the basis of HSI values. 2D shallow-water equations (SWEs), combined with remote sensing and geographic information system technology, were utilized to determine the key habitat features. Results indicated that the established HSI model could effectively recognize the potentially suitable habitats for Siberian cranes in Poyang Lake. The highly suitable habitat in the wet year was larger than that in the dry year, and the complexity of patch shapes and patch fragmentation increased. The influence of the PLHP on the suitable habitat for cranes mainly depended on its regulated water level, and this project could promote the formation and reduce the fragmentation degree of the suitable habitat under a properly regulated water level in the dry year. However, a higher regulated water level may cause a considerable negative impact on the distribution of suitable habitats in both years. This study provided a quantitative method to evaluate the potentially suitable habitats for Siberian cranes, and it could serve as a reference for the water level management of the proposed PLHP.

Determinants of fish distribution pattern and habitat preference in protected Karaj River, Iran

Lack of information about ichthyofauna makes it difficult to predict human effects on the communities. In this study, the effects of the environmental and human factors were examined on altitudinal patterns of fish habitat selection, faunal changes, species richness and fish abundance from upstream to downstream in the southern part of the central Alborz Protected Area during 2016 and 2017. 366 fish individuals of five species in three families were identified and brown trout was the dominant species. The river was divided into three zones based on habitat structure, species composition and influence of physical and chemical variables. The results indicate that, in some situations, including small changes in habitat structure indices, physical and chemical variables along the altitudinal gradient are more effective in habitat preference, describing the composition, and abundance. Chemical variables can help to have a better understanding of the conventional patterns, shaped by the habitat structure and physical variables. Habitat suitability index model for brown trout in three zones is completely different over the two years and this species could overcome these conditions. However, upstream areas were more appropriate. Dam, with decreases of outlet water temperature, also creates homogeneous and simple habitats leading to changes in expected fish distribution patterns with decreasing altitude. These conditions may have increased habitat suitability index for the brown trout in downstream, while despite favorable ecological conditions in the middle zone, habitat suitability index and alternative habitats available in this zone are likely to decline due to density and interspecific competition. The natural pattern of fish distribution and habitat selection varies along the altitudinal gradient due to various factors and human disturbances. Optimal management of protected areas can control the effects of some of these factors at least temporarily.

Habitat hierarchies distribution of Sargassum muticum in Lidao bay, Shandong, China based on habitat suitability index model.

We used the habitat suitability index (HSI) model to determine the habitat suitability of Sargassum muticum in Lidao bay, Shandong Province. Eight environmental factors, including temperature, salinity, depth, turbidity, sediment, inorganic nitrogen concentration, phosphate concentration, distance from seaweed bed, were used as input variables for HSI model. The weight of each factor was defined by the analytic hierarchy process (AHP). We implemented the distribution of S. muticum suitable habitat along the coast of Lidao bay with the HSI model, based on the investigation of the environmental factors in spring and autumn 2018. The results showed that most of the S. muticum natural habitats were identified as excellent habitat and suitable habitat, accounting for 14.2% in spring and 18.6% in autumn. The distribution of habitat hierarchies varied across seasons, while habitat hierarchies showed spatial intersections in different seasons. There were significant seasonal differences in the factor suitability indices of temperature and phosphate concentration, which accounted for the seasonal HSI variations of S. muticum in Lidao bay. The S. muticum HSI model could be used to detect the habitat hierarchies distribution of S. muticum, and also to find its potential suitable habitat, which could provide a reference for future resource conservation and artificial proliferation of S. muticum.

Impacts of El Niño(2007) and La Niña(2015) events on spatial and temporal distribution of potential habitat of <italic>Scomber japonicus</italic> in the East China Sea

Chub mackerel <italic>Scomber japonicus</italic> is one of economically important fish species in the ocean, and it is also an important fishing target for Chinese distant-water fishery. The resources of <italic>Scomber japonicus</italic> are strongly affected by environmental changes, thus understanding the response of changes in the habitat suitability of <italic>Scomber japonicus</italic> in the East China Sea to different anomalous climate conditions can help better know the stock dynamics of its resources and fishing grounds, and make sustainable exploitation of fishery resources of <italic>Scomber japonicus</italic>. According to the fishery data of <italic>Scomber japonicus</italic> obtained from National Data Center for Distant-water Fisheries of China at Shanghai Ocean University, combined with three key environmental factors: sea surface temperature (SST), sea surface height (SSH) and net primary productivity (NPP), this study investigated and compared the differences in the habitat of <italic>Scomber japonicus</italic> in the East China Sea between 2007 (a La Niña year) and 2015 (an El Niño year), based on the method of arithmetic average habitat suitability index (HSI) modeling analysis. The results showed that the catch, fishing effort and CPUE (catch per unit effort) of <italic>Scomber japonicus</italic> in the La Niña year (2007) was higher than those in the El Niño year (2015). The latitudinal gravity centers of fishing ground (LATG) in 2007 were in the northern waters compared with that of 2015. Comparing the environmental conditions between the two years, it was found that the spatial distributions of SST, SSH and NPP from July to September in 2007 were significantly different from those in 2015. The habitat modeling analysis indicated that the environmental conditions in 2007 were favorable for the formation of high-quality habitat for <italic>Scomber japonicas</italic>. Moreover, the areas of suitable habitat (HSI>0.6) from July to September in 2007 were significantly larger than that in 2015, and the location of suitable habitats in 2007 was northward compared with 2015, leading to the LATG in 2007 more northerly. Our findings suggested that La Niña and El Niño events strongly affected the ranges and spatial distributions of suitable habitats of <italic>Scomber japonicus</italic> in the East China Sea and the impacts showed large differences under different climate variabilities.

Applications of Integrating Wildlife Habitat Suitability and Habitat Potential Models

ABSTRACTAssessment of habitat suitability provides natural resource managers with insights on the quality and spatial distribution of habitat for wildlife species. However, habitat suitability models only provide information on current habitat parameters, and do not consider changes in habitat due to forest succession and disturbances. Habitat potential models have been developed by identifying habitat types and their successional trajectories to provide insights on how landscapes change with time. We developed habitat suitability index (HSI) models and habitat potential models for elk (Cervus elaphus nelsoni) on public and private lands within the Michigan elk range (1,220 km2) in northeastern lower Michigan, USA. Our objective was to demonstrate how integration of habitat suitability and habitat potential models can provide spatiotemporal insights on wildlife habitat. When constructing public‐lands models, we used state forest compartment‐inventory data to identify cover types important to elk, and assigned suitability values (0 = low, 1 = high) to each cover type for elk life requisites (i.e., spring food, winter food, winter thermal cover). Additionally, we modified suitability values based on stand conditions acquired from state forest inventory records (e.g., stand size, percent canopy closure, age of aspen [Populus spp.]). For our private‐lands models, we used satellite imagery to classify cover types and assigned suitability values to cover types for each elk life requisite, and modified values based on percent canopy closure for winter thermal cover. Elk habitat potential was modeled by delineating habitat types by overlaying digital spatial data layers (soils, land‐type associations, vegetation) and identifying successional trajectories using habitat classification guides and literature. We assigned suitability values to each habitat type for life requisites at early to late successional stages. The highest suitability value of each habitat type's successional stage determined the habitat potential for each habitat type. Our winter thermal cover HSI model indicated several large areas (5–13 km2) of high suitability (i.e., lowland conifers) in the southern third of our study area. Our winter food HSI model indicated a heterogeneous arrangement of high suitability areas (hardwoods, upland conifers, aspen) throughout our study area. Our spring food HSI model indicated few areas of high suitability (openings) primarily on private lands. Our habitat potential models indicated high potential for each elk life requisite across the elk range. Comparisons between current elk habitat suitability and habitat potential identify key areas where managers can maximize management efforts for elk in Michigan. Areas determined to have high habitat potential (e.g., mature aspen stands) may become focus areas if they currently have low habitat suitability. Conversely, managers can avoid committing resources to areas with low habitat potential. Integrating habitat suitability and potential models provides insights on how wildlife habitats may respond to forest succession, land management practices, and disturbances, and ultimately help natural resource professionals prioritize and meet a diversity of wildlife management goals. © 2021 The Wildlife Society.

Climate-related changes in seasonal habitat pattern of Sthenoteuthis oualaniensis in the South China Sea

ABSTRACT A habitat suitability index model (HSI) was established to examine seasonal habitat pattern of Sthenoteuthis oualaniensis in the South China Sea and assessed the impacts of the El Niño event on habitat variations based on sea surface temperature (SST), chlorophyll-a (Chla) and sea surface height (SSH). Environmental conditions and habitat patterns showed significant seasonal and spatial variations. Spatial pattern of favorable environmental conditions played important roles in regulating the ranges and longitudinal and latitudinal distributions of suitable habitats (areas with HSI≥0.6) of S. oualaniensis across seasons. Significant positive correlation was found between SST and HSI, whereas negative relationship was revealed between HSI and Chla as well as SSH by correlation analysis. Comparing to normal climate condition in spring 2014, the El Niño events in spring 2015 and 2016 yielded lower SST and higher Chla and SSH, which were unfavorable for the formation of high-quality habitats. Favorable ranges of environmental conditions showed decreasing trend from spring 2014 to 2016. Consequently, the suitable habitats in spring 2015 and 2016 largely contracted and became discontinuity. Our findings indicated that seasonal habitat patterns of S. oualaniensis in the South China Sea were strongly affected by the El Niño events and local environmental conditions.

Can La Redonda lagoon (Cuba) be a suitable habitat for largemouth bass (Micopterus salmoides, Lacepède) recovery?

For decades, La Redonda lagoon was an excellent location for fishing the largemouth bass (Micopterus salmoides, Lacepède) in Cuba. There are indications that the species disappeared from the lagoon in 2009. Three water surveys were carried out in 2013 and 2014. Physicochemical parameters, including nutrients, were measured in all surveys. Chlorophyllaand water transparency were only measured in November 2013. Results showed that this lagoon is a fresh to brackish water system, with common salinization episodes. There were some hypoxic conditions, but mean dissolved oxygen value was above 5.0 ± 2.8 mg L−1for the entire survey period. The trophic state was evaluated as oligotrophic and Nitrogen and Phosphorus were limiting in most of the survey sites. The Habitat Suitability Index model (HSI) for largemouth bass had a mean value of 0.63 ± 0.02 (moderate degree of suitability). All results showed that bass recovery could be possible in La Redonda lagoon, but management criteria are necessary. The largemouth bass recovery could help to increase visitations of American anglers to this place and a portion of the revenue could be used to conduct environmental monitoring and studies of the largemouth bass ecology in Cuba.

Spatial-temporal Distribution of Spawning Grounds in the Western Guangdong Waters Based on Habitat Suitability Index Model

Spatial-temporal Distribution of Spawning Grounds in the Western Guangdong Waters Based on Habitat Suitability Index Model

Trans-Pacific multidecadal changes of habitat patterns of two squid species

Trans-Pacific changes in the habitat patterns of neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean and jumbo flying squid (Dosidicus gigas) in the Southeast Pacific Ocean during 1950–2015 were examined on a decadal scale using a habitat suitability index (HSI) model. The HSI model involved two environmental drivers for the occurrence of O. bartramii and D. gigas: sea surface temperature (SST) and sea surface height anomaly (SSHA). Significant seesaw-like patterns of environmental variability and habitat changes, consistent with the regime shift of positive and negative Pacific Decadal Oscillation (PDO), were observed for the two squid species. In a negative PDO phase, SST anomaly and SSHA increased on the fishing grounds of O. bartramii. The areas of suitable habitat of O. bartramii contracted markedly due to the decrease in suitable SST and SSHA. In contrast, cooling SST and decreasing SSHA on the fishing grounds of D. gigas during a negative PDO phase led to the formation of more suitable SST and SSHA, yielding expansive suitable habitats for D. gigas. Moreover, the most favorable SST for O. bartramii and D. gigas moved northward in the negative PDO regime, and the suitable habitat for both squids shifted into the northern regions as well. When the climate regime shifted into a positive PDO phase, the responses of the two squids were opposite to those in the negative PDO phase. Our findings indicate that interannual-to-decadal variability in habitat patterns of O. bartramii and D. gigas can be detected from climate regime shifts in the Pacific Ocean.

Habitat suitability response to sea-level height changes: Implications for Ommastrephid squid conservation and management

Sea level rise, amplified by anthropogenic climate change, causes visible impacts on wildlife habitats in low-lying coastal areas. However, the potential consequences of sea level height (SLH) changes for pelagic fish habitats in the open oceans are poorly understood, especially for climate-sensitive Ommastrephid squid. In this study, the impacts of SLH changes were estimated under three different SLH change scenarios (5 cm, 20 cm, and 35 cm) for the western stock of winter-spring neon flying squid Ommastrephes bartramii, an ecologically- and commercially-important species in the northwest Pacific Ocean (NWPO). A habitat suitability index (HSI) modeling approach was applied to predict the habitat suitability of O. bartramii, using data from 2006 to 2014 for model construction and data from 2015 for model validation. Results showed that the decreasing catch-per-unit-effort (CPUE) of O. bartramii from 2006 to 2015 was highly correlated with the increases in sea level height (SLH). Significant positive relationships were found between the HSI values for latitudinal centers of gravity (LATGHSI) and SLH. The monthly-averaged HSI of O. bartramii was negatively correlated with the SLH, except in July and November. SLH scenarios revealed that the predicted suitable habitat (areas with HSI≥0.6) exhibited a decreasing trend with increasing SLH from August to October. In July and November, the suitable habitat initially increased in the +5 cm and +20 cm scenarios, but largely declined under the +35 cm scenario. The poor habitat (areas with HSI≤0.2) significantly increased under all SLH scenarios. A poleward shift of LATGHSI was observed under all scenarios. These findings suggest that the O. bartramii habitats in the NWPO are at risk to SLH changes and have important implications for better conservation and fishery management regarding pelagic short-lived Ommastrephid squid in global oceans.

Spatial Analysis of Potential Nesting Habitat for Florida Sandhill Cranes

AbstractThe Florida sandhill crane Antigone canadensis pratensis is designated as threatened by the state of Florida, where there is an urgent need to map and quantify available habitat. First, we used habitat suitability index (HSI) modelling to map and assess potential nesting habitat for sandhill cranes in Florida. Second, we used spatial optimization approaches to calculate the maximum number of breeding pairs that can simultaneously occupy potential nests given that they both must be of some minimum quality and must be spaced some minimal distance apart. Mapping results reveal that nesting habitat is concentrated in the central portion of the state, with adequate brooding habitat appearing to be the most limiting factor affecting habitat suitability. Assuming nesting only occurs in habitat rated as high quality (HSI ≥ 0.7) and spacing between adjacent nests is ≥1,000 m, we conservatively estimate that 5,540 nesting pairs of Florida sandhill cranes can potentially be supported. Additional nesting pairs may be supported in habitats of marginal (HSI ≥ 0.3; 14,530) to moderate (HSI ≥ 0.5; 8,723) quality. The suitability maps and breeding pair estimates can be used to identify important habitat areas to focus crane conservation efforts, determine potentially limiting habitat features across the landscape, and potentially guide future population monitoring efforts. For example, grassland or prairie restoration could be used to potentially increase nesting pairs in the southern portion of the state where emergent wetlands are abundant but brooding habitat is lacking.

A Migration Model to Predict the Distribution of Scottish Herring and Mackerel

To identify climate-related habitat changes and variations in abundance and distribution of herring and mackerel around the waters of Scotland, a new habitat suitability index (HSI) model and Markov Model were developed in this study. The study only used the distribution of annual catch and fishing efforts. The suitability index (SI) was constructed by newly defined estimate-catch-per-unit-effort (ECPUE). Through the voting method and data of sea surface temperature (SST), the habitat suitability index model (HSI) was established. Based on the HSI, Markov Model was established to predict the movement of shoals. Using the predicted data of future SST, this model can simulate the changes of fish distribution.

Development and evaluation of habitat suitability models for nesting white-headed woodpecker (Dryobates albolarvatus) in burned forest.

Salvage logging in burned forests can negatively affect habitat for white-headed woodpeckers (Dryobates albolarvatus), a species of conservation concern, but also meets socioeconomic demands for timber and human safety. Habitat suitability index (HSI) models can inform forest management activities to help meet habitat conservation objectives. Informing post-fire forest management, however, involves model application at new locations as wildfires occur, requiring evaluation of predictive performance across locations. We developed HSI models for white-headed woodpeckers using nest sites from two burned-forest locations in Oregon, the Toolbox (2002) and Canyon Creek (2015) fires. We measured predictive performance by developing one model at each of the two locations and quantifying discrimination of nest from reference sites at two other wildfire locations where the model had not been developed (either Toolbox or Canyon Creek, and the Barry Point Fire [2011]). We developed and evaluated Maxent models based on remotely sensed environmental metrics to support habitat mapping, and weighted logistic regression (WLR) models that combined remotely sensed and field-collected metrics to inform management prescriptions. Both Maxent and WLR models developed either at Canyon Creek or Toolbox performed adequately to inform management when applied at the alternate Toolbox or Canyon Creek location, respectively (area under the receiver-operating-characteristic curve [AUC] range = 0.61-0.72) but poorly when applied at Barry Point (AUC = 0.53-0.57). The final HSI models fitted to Toolbox and Canyon Creek data quantified suitable nesting habitat as severely burned or open sites adjacent to lower severity and closed canopy sites, where foraging presumably occurs. We suggest these models are applicable at locations similar to development locations but not at locations resembling Barry Point, which were characterized by more (pre-fire) canopy openings, larger diameter trees, less ponderosa pine (Pinus ponderosa), and more juniper (Juniperus occidentalis). Considering our results, we recommend caution when applying HSI models developed at individual wildfire locations to inform post-fire management at new locations without first evaluating predictive performance.

Optimization of environmental variables in habitat suitability modeling for mantis shrimp Oratosquilla oratoria in the Haizhou Bay and adjacent waters

Habitat suitability index (HSI) models have been widely used to analyze the relationship between species abundance and environmental factors, and ultimately inform management of marine species. The response of species abundance to each environmental variable is different and habitat requirements may change over life history stages and seasons. Therefore, it is necessary to determine the optimal combination of environmental variables in HSI modelling. In this study, generalized additive models (GAMs) were used to determine which environmental variables to be included in the HSI models. Significant variables were retained and weighted in the HSI model according to their relative contribution (%) to the total deviation explained by the boosted regression tree (BRT). The HSI models were applied to evaluate the habitat suitability of mantis shrimp Oratosquilla oratoria in the Haizhou Bay and adjacent areas in 2011 and 2013–2017. Ontogenetic and seasonal variations in HSI models of mantis shrimp were also examined. Among the four models (non-optimized model, BRT informed HSI model, GAM informed HSI model, and both BRT and GAM informed HSI model), both BRT and GAM informed HSI model showed the best performance. Four environmental variables (bottom temperature, depth, distance offshore and sediment type) were selected in the HSI models for four groups (spring-juvenile, spring-adult, fall-juvenile and fall-adult) of mantis shrimp. The distribution of habitat suitability showed similar patterns between juveniles and adults, but obvious seasonal variations were observed. This study suggests that the process of optimizing environmental variables in HSI models improves the performance of HSI models, and this optimization strategy could be extended to other marine organisms to enhance the understanding of the habitat suitability of target species.

Spatial Habitat Suitability Models of Mangroves with Kandelia obovata

Mangrove forests provide important estuarine ecosystem services but are threatened by rising sea levels and anthropogenic impacts. Understanding the habitat characteristics required for mangrove growth is significant for mangrove restoration and integrated management. This study aims to build spatial habitat suitability index (HSI) models for Kandelia obovata mangrove trees. Biological and habitat-related environmental data were collected in the Wazwei and Guandu wetlands in northern Taiwan. We adopted inundation frequency, soil sorting coefficient, and water salinity as the key environmental factors to build HSI models. The dependent variable of these environmental factors was the mangrove biomass per unit area. Significant differences were found for the mangrove biomass on different substrata and shore elevations. The tidal creek had the lowest elevation, and mangrove areas were found at the highest elevations. The oxidization level of the substrate under mangrove forests was high, indicating that the root system of mangroves could carry oxygen into the soil and result in oxidation. Human activities were found to lead to the reduced growth conditions of mangroves. The validation of the HSI model, considering the inundation frequency and soil sorting coefficient, proved to be reliable, with an accuracy ranging from 78% to 90%. A better simulation was found after revising the model by incorporating the factor of water salinity. The model forecast of the mangrove responses to the sea-level rise indicated an increase in the inundation frequency and thus an induced shift and shrinkage of the mangrove area. The increased HSI values of the bare mudflat area demonstrate an option for the potential restoration of mangrove trees. Given the findings of this study, we concluded that mangroves could spread from estuaries to upstream areas due to rising sea levels and might be limited by humanmade impacts. Restoring degraded floodplains is suggested for mangrove habitat rehabilitation.

Effect of Beaver on Brook Trout Habitat in North Shore, Lake Superior, Streams

AbstractThe Brook Trout Salvelinus fontinalis is a native salmonid that provides a valued and productive sport fishery in northeastern Minnesota. Revival of North American beaver Castor canadensis (hereafter, “beaver”) populations since their near extermination and concern over their impacts on Brook Trout habitat prompted a reexamination of the complex ecological relationship where the two taxa interact. Suitable Brook Trout habitat is characterized by cold, spring‐fed water with silt‐free rocky substrate and abundant cover, all of which beaver may directly or indirectly affect. Data collection occurred on 79 stream sections (200 m each) and 21 beaver ponds spanning the North Shore of Lake Superior during the summer in 2017 and 2018. Habitat suitability index (HSI) models determined the average HSI and quantity of suitable Brook Trout habitat (m2/100 m2) at stream and beaver pond sites, and a bioenergetics model calculated Brook Trout growth availability (m2/100 m2) and mean growth (g/d) at stream sites. Classification regression trees identified significant thresholds at which beaver activity (e.g., number of dams upstream of sampled sites and beaver pond age) influenced the quantity or quality of Brook Trout habitat and growth. No significant variables were identified as affecting Brook Trout habitat or growth rates in stream sites. Alternatively, the quantity and quality of Brook Trout habitat in this region appeared to be influenced by microhabitat variables (depth, velocity, and temperature) that are eminent at individual stream sites. Brook Trout growth was strongly influenced by velocity (m/s) and mean prey concentration (mg dry mass/m3). Results indicated that 12 of the 21 sampled beaver ponds contained suitable Brook Trout habitat, with dissolved oxygen (mg/L) identified as a threshold. This study recommends focusing on individual stream characteristics and beaver pond dissolved oxygen concentrations to achieve desired Brook Trout habitat and aid in the development of management strategies pertaining to these two taxa in Lake Superior's North Shore streams.

Spatio-temporal variations in the potential habitat of a pelagic commercial squid

An integrated habitat suitability index (HSI) model was developed for a pelagic commercial squid Ommastrephes bartramii in the Northwest Pacific Ocean based on three crucial environmental variables: sea surface temperature (SST), chlorophyll-a concentration (Chla) and sea surface height (SSH). The model was established by data from 2006 to 2014 and validated by data in 2015 on the basis of fishing effort and CPUE (catch-per-unit-effort). Results suggested that the HSI model had good capacity to predict habitat suitability for O. bartramii . Squid habitat quality showed significant monthly variation, the ranges of suitable habitats in July and August were much larger than those in September. Besides, the latitudinal location of suitable habitats gradually moved northward from July to September. Further, the spatial extents of potential habitat of O. bartramii across months were strongly regulated by favorable environmental conditions. The variability trends of monthly CPUE and LATG (latitudinal distribution of fishing efforts) were closely associated and consistent with spatio-temporal habitat variations during 2006–2015. Moreover, climate variability strongly affected habitat variations and squid stocks. Relative to the El Niño event in 2015, the La Niña event in 2007 yielded expanded suitable habitat from July to September, consequently, the CPUE was much higher. And the potential high-quality habitats in 2007 mainly located in northern regions except July comparing to 2015, leading to the higher latitudinal distribution of LATG in August and September 2007. Our findings indicated that O. bartramii habitats obviously varied from month to month and were largely affected by environmental changes. • Habitat patterns of Ommastrephes bartramii was examined by habitat modeling approach. • Spatio-temporal variations of O. bartramii habitats showed monthly patterns. • Climatic and environmental variability strongly affected O. bartramii habitats.

Hit or miss? Evaluating the effectiveness of Natura 2000 for conservation of forest bird habitat in Sweden

Biodiversity conservation often requires a landscape perspective. When establishing the Natura 2000 (N2k) network, the effectiveness of the sites and the influence of the surrounding landscapes for species of interest was often disregarded. We analyzed the effectiveness of N2k sites in Sweden for three forest bird species of conservation interest in the European boreal landscapes: lesser spotted woodpecker (LSW), Siberian jay (SJ) and hazel grouse (HG). Our objectives were to: 1) quantify effective suitable habitat area in N2k sites with and without consideration of the adjoining landscapes; 2) examine effective habitat area within N2k sites along the north-south vegetation gradient 3) analyze functionality of N2k sites and assess how forests outside the sites affect habitat suitability inside N2k. GIS-based habitat suitability index models were applied to calculate the amount of effective habitat within and outside N2k sites. N2k sites contributed with 10% (HG), 13% (SJ) and 51% (LSW) suitable habitat identified in Sweden. Functionality of forest environments as habitat was higher inside N2k sites for LSW within all vegetation zones, and for SJ in the Alpine and Middle Boreal zones; for HG habitat outside the sites was more functional in all zones accept Alpine and Middle Boreal. The majority of N2k sites were of quite small size (<500 ha) and the size influenced their functionality for LSW and HG, with larger N2k sites being more functional. For SJ, however, average functionality of N2k sites was not influenced by their size. The largest average habitat increase linked to considering the contribution of areas outside N2k sites for their functionality as habitat was for the N2k sites of smaller size (1-500 ha). Therefore, the presence and quality of forests outside of N2k sites are of a greater importance for smaller sites, and as such these should be carefully managed. To improve conservation efficiency of the N2k sites in Sweden, we call for incorporating them into the development and implementation of the regional Green Infrastructure plans.

Integrating Large Wood Jams into Hydraulic Models: Evaluating a Porous Plate Modeling Method

AbstractLarge wood (LW) jams are key riverine habitat features that affect hydraulic processes and aquatic habitat. The hydraulic influence of LW jams is poorly understood due to the complexity of fluid dynamics around irregular, porous structures. Here we validated a method for two‐dimensional hydraulic modeling of porous LW jams using the open‐source modeling software Delft3D‐FLOW. We sampled 19 LW jams at three reaches across the Columbia River Basin in the United States. We used computer‐generated porous plates to represent LW jams in the modeling software and calibrated our modeling method by comparing model outputs to measured depths and velocities at validation points. We found that modeling outputs are error‐prone when LW jams are not represented. By representing LW jams as porous plates we reduced average velocity root mean square error (RMSE) values (i.e., improved model accuracy) by 42.8% and reduced average depth RMSE values by 5.2%. These differences impacted habitat suitability index modeling. We found a 15.1% increase in weighted useable area for juvenile steelhead at one test site when LW jams were simulated vs. when they were ignored. We investigated patterns in average RMSE improvements with varying jam size, bankfull obstruction, porosity, and structure type, and river complexity. We also identified research gaps related to field estimation of LW jam porosity and porous structure modeling methods.