Scale-Dependent Habitat Selection of Nesting Great Egrets and Snowy Egrets

Foraging habitat selection of nesting Great Egrets ( Ardea alba ) and Snowy Egrets ( Egretta thula ) was investigated within an estuary with extensive impounded salt marsh habitat. Using a geographic information system, available habitat was partitioned into concentric bands at five, ten, and 15 km radius from nesting colonies to assess the relative effects of habitat composition and distance on habitat selection. Snowy Egrets were more likely than Great Egrets to depart colonies and travel to foraging sites in groups, but both species usually arrived at sites that were occupied by other wading birds. Mean flight distances were 6.2 km (SE = 0.4, N = 28, range 1.8-10.7 km) for Great Egrets and 4.7 km (SE = 0.48, N = 31, range 0.7-12.5 km) for Snowy Egrets. At the broadest spatial scale both species used impounded (mostly salt marsh) and estuarine edge habitat more than expected based on availability while avoiding unimpounded (mostly fresh water wetland) habitat. At more local scales habitat use matched availability. Interpretation of habitat preference differed with the types of habitat that were included and the maximum distance that habitat was considered available. These results illustrate that caution is needed when interpreting the results of habitat preference studies when individuals are constrained in their choice of habitats, such as for central place foragers.

Distribuição espacial dos foraminíferos no perfil transversal ao manguezal da margem da baía de Sepetiba-RJ: habitat e paleoambiente

Os foraminíferos de zona entre-marés são amplamente utilizados como na reconstituição paleoambiental holocênica. Entretanto, a despeito dos manguezais, estudos com foraminíferos são relativamente escassos. A estrutura do habitat e seu grau de exposição atuam na distribuição espacial das espécies de zona entre-marés. Em um perfil transversal ao manguezal que margeia a baía de Sepetiba (RJ), foi investigada a influência parâmetros estruturais do habitat e da riqueza na distribuição espacial dos foraminíferos do manguezal. Os parâmetros escolhidos neste estudo foram serapilheira, litologia, matéria orgânica total, microtopografia, zonação botânica, espécies botânicas, altura média das árvores e densidade de árvores. Um testemunho de 144 cm também foi descrito em termos da sua litologia, matéria orgânica total, composição biogênica, incluído foraminíferos. O perfil apresentou textura silte argilosa, matéria orgânica total concentrada por todo manguezal e a serapilheira acumulada principalmente no mangue superior. Os forminíferos (24) ocorreram apenas no manguezal, com predomínio de aglutinantes e presença significativa de formas calcárias. A densidade de testas se concentrou no mangue superior. A. beccarii f. tepida, E. excavatum, A. mexicana, Q. seminulum e T. inflata foram as espécies mais constantes. A diversidade não apresentou variabilidade espacial significativa e foi marcada pela baixa dominância e alta equitabilidade. Notou-se diferença significativa da riqueza de foraminíferos entre habitats expostos e protegidos. A riqueza específica apresentou moderada correlação com a serapilheira e densidade de árvores. A. mexicana e H. wilberti apresentaram moderada correlação com a riqueza. Q. seminulum apresentou significativa correlação com a matéria orgânica total e altura média das árvores. T. inflata apresentou significativa correlação com a riqueza e serapilheira. Em relação ao testemunho, foi possível identificar três paleoambientes de baía restrita: infralitoral, mesolitoral e supralitoral. O manguezal este presente entre o nível 124 62 cm e a planície hipersalina a partir do nível 24 cm.

Variations saisonnières des facteurs hydrologiques et du biovolume microalgal benthique au sein d'un habitat artificiel (acadja-enclos) dans la lagune Ebrié: site d'Adjapoté

This paper presents the results of a comparative study of chemical and physical characteristics (temperature, oxygen, salinity, turbidity, pH, nutrient: phosphates, nitrates, nitrites, ammoniac) within the extensive aquaculture structure (acadja-enclosure or artificial habitats for fishes) and in the surrounding water. Biological characteristics of the periphyton growing on bamboos from acadja-enclosure were also described.

River Wyre salmon and sea trout spawning habitat restoration / creation project. Final report April 1995

Adult salmon and sea trout rod catches in the River Wyre have been subject to considerable variability over the years. Annual rod catches ranging from 6 to 401 have been reported since records began in 1905. It has long been suspected that the physical nature of the catchment, combined with anthropogenic influences, has resulted in a deleterious effect on the Wyre fishery. Acidification problems in the head water streams (Marshaw Wyre and Tarnbrook Wyre) have been reported and are thought to threaten salmon juvenile survival. The construction of Abbeystead Reservoir and an increased tendency towards rapidly rising water levels during storms (flashiness) 1 are thought to have a significant impact on spawning gravel quality and quantity, both of which are thought to be deteriorating. As part of an overall desire to maintain and improve the migratory salmonid population in the River Wyre, this project has been commissioned to investigate remedial action which may improve and enhance spawning success, leading to an eventual improvement in the status of adult stocks. The primary objective is to establish whether the quantity and/or quality of available spawning gravels are limiting migratory salmonid productivity. The investigations undertaken confirm the general observation that useable spawning gravels appear to be in short supply in the River Wyre, and may be the limiting factor influencing returning adult stock.

A working guide to the assessment, implementation and post project monitoring of fisheries habitat improvement schemes in South Cumbria

Due to changes in land use over the last century, the physical nature of many streams and rivers in the British Isles has probably changed. In some cases this change may be large for example as a result of flood defence schemes and is easily observed, whilst in other cases altered land use, farming, forestry or urbanization may have resulted in more subtle changes to river features. This working guide draws together a way of assessing habitat in any stream or river and determine sites or reaches on the assessed watercourse that may benefit from habitat improvement schemes. It will determine a method of measuring existing habitat in a broad sense, whilst referring to R and D studies currently being undertaken in this area. A method of prioritising any proposed habitat restoration work will be suggested. The limitations of fisheries improvement schemes in terms of cross functional acceptance (flood defence and conservation) will be examined along with suggested proposals for some example watercourses. The need for pre and post enhancement monitoring will be discussed as will the requirement for maintenance programs on schemes. Finally methods for determining the cost benefits of small schemes will be examined, compared to other currently used enhancement strategies. This will allow small scale revenue schemes to be used to back up pre project cost benefit analysis as required in future capital submissions.

Rivers Ribble and Hodder - habitat improvement

In order to improve the habitat of the Rivers Ribble and Hodder in the north west of England it is necessary to assess existing fish stocks. To assist the Ribble Fisheries Association a test census of stock has been made on the rivers Hodder and Ribble. The fish have been taken by electro fishing techniques. The following fish were collected over six days in September 1965: dace, chub, grayling, eel, salmon and trout. This short report summarises the findings of the survey.

River Wyre salmon and sea trout spawning habitat restoration / creation project. Gravel enhancement schemes.

As part of an overall desire to maintain and improve the migratory salmonid population in the River Wyre, a project was commissioned to investigate remedial action which may improve and enhance spawning success and lead to an eventual improvement in the status of adult stocks. The report, titled "River Wyre Salmon and Sea Trout Spawning Habitat Restoration/Creation Project", concluded that usable spawning gravels appeared to be in short supply in the River Wyre catchment and may be the limiting factor influencing the returning adult stock, as juvenile nursery habitat was not found to be limiting. This report looks at gravel enhancement schemes to improve River Wyre salmon and sea trout spawning habitat restoration. It examines methods for gravel enhancement schemes: mechanical cleaning and construction of gravel addition structures. Includes sites figures of sites identified for enhancement.

Habitat degradation - its nature, causes and treatment

Since the latter part of the 19th century the Ribble and its tributaries have suffered habitat degradation to varying degrees. This report examims the causes for its degradation, specific problems and their treatment, progress, plans and procedures, and benefits of restoration including species identified by English Nature as threatened or declining and which are listed in the UK Biodiversity Action Plan.

Distribution, movements, and habitat use of small striped bass (Morone saxatilis) across multiple spatial scales

Distribution, movements, and habitat use of small (<46 cm, juveniles and individuals of unknown maturity) striped bass (Morone saxatilis) were investigated with multiple techniques and at multiple spatial scales (surveys and tag-recapture in the estuary and ocean, and telemetry in the estuary) over multiple years to determine the frequency and duration of use of non-natal estuaries. These unique comparisons suggest, at least in New Jersey, that smaller individuals (<20 cm) may disperse from natal estuaries and arrive in non-natal estuaries early in life and take up residence for several years. During this period of estuarine residence, individuals spend all seasons primarily in the low salinity portions of the estuary. At larger sizes, they then leave these non-natal estuaries to begin coastal migrations with those individuals from nurseries in natal estuaries. These composite observations of frequency and duration of habitat use indicate that non-natal estuaries may provide important habitat for a portion of the striped bass population.

Comparison of habitat-based indices of abundance with fishery-independent biomass estimates from bottom trawl surveys

Rockfish species are notoriously difficult to sample with multispecies bottom trawl survey methods. Typically, biomass estimates have high coefficients of variation and can fluctuate outside the bounds of biological reality from year to year. This variation may be due in part to their patchy distribution related to very specific habitat preferences. We successfully modeled the distribution of five commercially important and abundant rockf ish species. A two-stage modeling method (modeling both presence-absence and abundance) and a collection of important habitat variables were used to predict bottom trawl survey catch per unit of effort. The resulting models explained between 22% and 66% of the variation in rockfish distribution. The models were largely driven by depth, local slope, bottom temperature, abundance of coral and sponge, and measures of water column productivity (i.e., phytoplankton and zooplankton). A year-effect in the models was back-transformed and used as an index of the time series of abundance. The abundance index trajectories of three of five species were similar to the existing estimates of their biomass. In the majority of cases the habitat-based indices exhibited less interannual variability and similar precision when compared with stratified survey-based biomass estimates. These indices may provide for stock assessment models a more stable alternative to current biomass estimates produced by the multispecies bottom trawl survey in the Gulf of Alaska.

Análise espaço-temporal do uso do habitat pelo boto-cinza (Sotalia Guianensis) na Baía de Guanabara, Rio de Janeiro

Determinar áreas de vida tem sido um tema amplamente discutido em trabalhos que procuram entender a relação da espécie estudada com as características de seu habitat. A Baía de Guanabara abriga uma população residente de botos-cinza (Sotalia guianensis) e o objetivo do presente estudo foi analisar o uso espacial de Sotalia guianensis, na Baía de Guanabara (RJ), entre 2002 e 2012. Um total de 204 dias de coleta foi analisado e 902 pontos selecionados para serem gerados os mapas de distribuição. A baía foi dividida em quatro subáreas e a diferença no esforço entre cada uma não ultrapassou 16%. O método Kernel Density foi utilizado nas análises para estimativa e interpretação do uso do habitat pelos grupos de botos-cinza. A interpretação das áreas de concentração da população também foi feita a partir de células (grids) de 1,5km x 1,5km com posterior aplicação do índice de sobreposição de nicho de Pianka. As profundidades utilizadas por S. guianensis não apresentaram variações significativas ao longo do período de estudo (p = 0,531). As áreas utilizadas durante o período de 2002/2004 foram estimadas em 79,4 km com áreas de concentração de 19,4 km. Os períodos de 2008/2010 e 2010/2012 apresentaram áreas de uso estimadas em um total de 51,4 e 58,9 km, respectivamente e áreas de concentração com 10,8 e 10,4 km, respectivamente. As áreas utilizadas envolveram regiões que se estendem por todo o canal central e região nordeste da Baía de Guanabara, onde também está localizada a Área de Proteção Ambiental de Guapimirim. Apesar disso, a área de vida da população, assim como suas áreas de concentração, diminuiu gradativamente ao longo dos anos, especialmente no entorno da Ilha de Paquetá e centro-sul do canal central. Grupos com mais de 10 indivíduos e grupos na classe ≥ 25% de filhotes em sua composição, evidenciaram reduções de mais de 60% no tamanho das áreas utilizadas. A população de botos-cinza vem decrescendo rapidamente nos últimos anos, além de interagir diariamente com fontes perturbadoras, sendo estas possíveis causas da redução do uso do habitat da Baía de Guanabara. Por esse motivo, os resultados apresentados são de fundamental importância para a conservação desta população já que representam consequências da interação em longo prazo com um ambiente costeiro altamente impactado pela ação antrópica.

A modeling approach to identify optimal habitat and suitable fishing grounds for neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean

We developed a habitat suitability index (HSI) model to understand and identify the optimal habitat and potential fishing grounds for neon f lying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean. Remote sensing data, including sea surface temperature, sea surface salinity, sea surface height, and chlorophyll-a concentrations, as well as fishery data from Chinese mainland squid f leets in the main fishing ground (150–165°E longitude) from August to October, from 1999 to 2004, were used. The HSI model was validated by using fishery data from 2005. The arithmetic mean modeling with three of the environmental variables—sea surface temperature, sea surface height anomaly, and chlorophyll- a concentrations—was defined as the most parsimonious HSI model. In 2005, monthly HSI values >0.6 coincided with productive fishing grounds and high fishing effort from August to October. This result implies that the model can reliably predict potential f ishing grounds for O. bartramii. Because spatially explicit fisheries and environmental data are becoming readily available, it is feasible to develop a dynamic, near real-time habitat model for improving the process of identifying potential fishing areas for and optimal habitats of neon flying squid.

Environmental characterization of seasonal trends and foraging habitat of bottlenose dolphins (Tursiops truncatus) in northern Gulf of Mexico bays

A description of the foraging habitat of a cetacean species is critical for conservation and effective management. We used a fine-scale microhabitat approach to examine patterns in bottlenose dolphin (Tursiops truncatus) foraging distribution in relation to dissolved oxygen, turbidity, salinity, water depth, water temperature, and distance from shore measurements in a highly turbid estuary on the northern Gulf of Mexico. In general, environmental variation in the Barataria Basin marine environment comprises three primary axes of variability (i.e., factors: temperature and dissolved oxygen, salinity and turbidity, and distance and depth) that represent seasonal, spatial-seasonal, and spatial scales, respectively. Foraging sites were differentiated from nonforaging sites by significant differences among group size, temperature, turbidity, and season. Habitat selection analysis on individual variables indicated that foraging was more frequently observed in waters 4–6 m deep, 200–500 m from shore, and at salinity values of around 20 psu. This fine-scale and multivariate approach represents a useful method of exploring the complexity, gradation, and detail of the relationships between environmental variables and the foraging distribution patterns of bottlenose dolphin.

Assessment of habitat quality for juvenile California halibut (Paralichthys californicus) in a seasonally arid estuary

We evaluated habitat quality for juvenile California halibut (Paralichthys californicus) in a Pacific Coast estuary lacking in strong salinity gradients by examining density, recent otolith growth rates, and gut fullness levels of wild-caught and caged juveniles for one year. Juveniles <200 mm standard length were caught consistently in the inner, central, and outer sections of the estuary. The density of juveniles was two times higher in the inner estuary during most of the year, consistent with active habitat selection by part of the population. A generalized linear model indicated temperature, sampling time, and the interaction between salinity and temperature were significantly related to density. However, the model explained only 21% of the variance. Gut fullness levels of wild-caught juveniles were highest during the summer, but recent otolith growth rates were not related to temperature. The proportion of individuals feeding successfully indicated that seasonal differences in food availability are more important than spatial variation in prey abundance in driving feeding success. Feeding success of caged fishes was limited, precluding the use of growth rates as indicators of local habitat quality. However, marginal increment widths were reliable indicators of somatic growth at low growth rates over two-week periods. The relatively high growth rates and abundance of small wild-caught juveniles found throughout the estuary indicates that the entire estuary system has the potential for serving as nursery habitat.