Trophic Spectrum Research Articles

Fatty acids composition as an indicator of food intake inMerluccius hubbsilarvae

AbstractFatty acids (FA) analysis is a well-established approach for qualitatively studying feeding preferences. In the Argentinean Continental Shelf, Argentine hakeMerluccius hubbsisupports the major demersal finfish fishery. The Patagonian stock of the species spawns and nurses in austral summer in the north Patagonian shelf (NPS, 43°–45°30′S). Previous studies about larval feeding in the NPS have solely focused on gut contents, indicating selectivity upon calanoid copepods. Hence, our main objective was to apply the FA approach to confirm and/or broadenM. hubbsilarval food selection. Hake larvae and copepod FA profiles overlapped significantly, dominated by the saturated FA 16:0, the monounsaturated FAs 18:1n-9 and 22:1n-9, and the polyunsaturated FA 22:6n-3. Moreover, identified markers typical of bacteria (15:0, 17:0) and dinoflagellates (18:4n-3, 22:6n-3) suggest a microbial input at the base of the NPS food web, with the latter probably acting as an intermediate step between bacteria and hake larvae. Possible direct predation upon protozoans by larvae is postulated, broadening the known trophic spectrum derived from classical diet analyses. The FA approach allowed us to clarify feeding preferences in the NPS, with data being relevant in the context of hake recruitment studies.

An approach towards quantification of ecosystem trophic status and health through ecological network analysis applied in Hooghly-Matla estuarine system, India

The structure and function of food web of Hooghly-Matla estuarine system (HMES) including Sundarban mangroves is studied to assess the health of the system. HMES, provides shelter and make a home to many economically important shell and fin fishes. This estuary is exposed to various threats such as increasing salinity, deterioration of soil fertility and productivity, pollution and loss of biodiversity. Ecological network analysis (ENA) is applied for the HMES to model the trophic flows in 22 ecological compartments using Ecopath (a software for network analysis), integrating ecological data for the 2013–2015. ENA is performed, including a set of indices, keystoneness and trophic spectrum analysis to describe the contribution of the 22 groups to the HMES functioning. Results show that 22 compartments of the HMES including primary producers (trophic level TL 1) to the top consumers (elasmobranch, TL 3.5), the ecotrophic efficiency ranges from 0.016 to 0.989. Small demersal fishes, prawns, shrimps and crabs are the most exploited groups of this ecosystem. Herbivory and detritivory ratio is 1:1 indicating relative absence of top predators and low maturation level. Maturity of the system, organization, relative order and disorder within the system, diversity of flow of material among compartments and overhead of the system has been assessed. Biomass over Total system throughput ratio (TB/TST), Total primary production over total respiration ratio (TPP/TR), Total primary production over biomass (TPP/TB) and system omnivory index (SOI) indicate the moderate maturity level of the system. The HMES trophic network has a moderate recycling level (FCI = 12.99%), a high total system throughput (TST = 22976.03 tonnes km−2 yr−1) and a low ascendency (A = 25799 tonnes km−2 yr−1), but a relatively low connectance (CI = 0.27), high internal relative ascendency (A = 29.6%) and a high omnivory index (OI = 0.203), indicating that this estuary is immature but relatively organized and complex, with strong production. HMES has some unique features in comparison to similar functioning geographically close estuaries or estuaries with similar environmental characteristics. System robustness and exergy are also estimated to assess ecosystem health and compared with other tropical systems. From a holistic point of view, present study conveys fundamental information and categorizes the status of the system.

Diversification of foraging habits among Guadalupe fur seals from their only well-established breeding colony, Guadalupe Island, Mexico

Intra-population resource partitioning is a foraging strategy that could minimize intra-specific competition. This behavior may be ecologically relevant for species in recovery like the Guadalupe fur seal Arctocephalus philippii townsendi (GFS), which was considered extinct 70–80 years ago. The present study provides, via scat and stable isotope (δ15N and δ13C) analyses, trophic knowledge around GFSs from Guadalupe Island just prior to and the 2013 breeding season, with emphasis on inter-individual variability. A total of 107 scat samples were analyzed, and 98 neonate fur samples (proxies for adult female foraging) were isotopically assessed. The overall trophic spectrum included 12 items, with a slight increase in diversity among main prey during the second half of the breeding season. The isotopic analysis revealed three distinct groups, reflecting apparent variations in trophic position and coastal/oceanic habitat use. As in previous studies, a mostly teutophagous diet was clear; however, our work is the first to identify inter-individual prey and habitat partitioning. Based on our results and those of other studies, GFSs exhibited an opportunistic foraging strategy across the breeding season. Both analyses were complementary in terms of diversification and useful for the understanding GFS foraging strategies, which are relevant to evaluating population recovery as factors such as prey availability is suggested to be critical to this species recovery.

The continuous trophic spectrum of food web in Dalian marine area, China.

This study analyzed the values of δ13C and δ15N by the application of stable isotope technique from the marine mammals (Phoca largha, Neophocaena asiaorientalis sunameri, Balaenoptera acutorostrata) and major biological species in Dalian marine area based on the animals collected due to stranding and death after bycatch from January, 2008 to June, 2017, and the fisheries resources investigation between autumn, 2016 and spring, 2017 in the same area. The trophic level was then calculated in order to establish the continuous trophic spectrum of the food web in Dalian marine area. The results showed that the value of δ15N ranged from 8.0‰ to 14.7‰ and the value of δ13C ranged from -21.1‰ to -16.7‰ of the food web in Dalian marine area. The major biological species could be categorized into three groups, namely primary consumer, secondary consumer and top predator. The analysis of δ15N revealed that the trophic level ranged from 2.63 to 4.59 for the major biological species. The trophic level of B. acutorostrata, N. asiaorientalis sunameri, P. largha, echinoderm, cephalopods, gastropod, bivalve, crustacean and fish were 3.16, 4.11, 4.25, 3.24-3.84, 3.81-3.93, 3.65-4.13, 2.63-3.15, 3.58-4.12 and 3.20-4.59, respectively. The characteristics of the trophic structure demonstrated that the primary consumer was bivalve, the secondary consumers were B. acutorostrata, cephalopods, Echinoderms, gastropod and crustacean, and top predators were N. asiaorientalis sunameri, P. largha and fish. The value of δ15N increased with the increase in the body length, indicating the feeding of N. asiaorientalis sunameri tended to be at a higher trophic level with the growth and feeding ability enhanced. This study established the continuous trophic spectrum of food web in Dalian marine area and would provide the information for the marine mammal and fisheries resources protection.

Dietary overlap among ruminants, geese, and lemmings of Wrangel Island in summer

Trends in the dynamics of herbivore community related to trophic competition in summer have been analyzed on Wrangel Island. The results show that the trophic spectra overlap considerably, resources are partitioned on the principle “weak competitors after strong competitors,” and community dynamics in the absence of extermination depend on specific competitive advantages related to the width of food spectrum. We conclude that the dynamics of this insular community prior to the establishment of nature reserve on the island have been determined by human activities, as well as the structure of arctic herbivore communities in general.

Ecología y reproducción de Opsanus beta (Actinopterygii: Batrachoididae) en la Laguna de Alvarado, Veracruz, México

Opsanus beta is a permanent species in the Alvarado Lagoon System (ALS), Veracruz, and eventhough it is not of economic importance, it might be actively involved in the energy transfer of the system. Currently, there is no information about the reproductive and ecological characteristics of this common fish, so this work aimed to evaluate those aspects, and to contribute with some ecological features. For this, a total of six sampling sites were selected and studied from April 2008 to December 2012. Per site, we determined fish seasonality, feeding, sex ratio, gonadosomatic index, hepatosomatic and condition factors for both sexes, as well as the fecundity and length-weight relationships. We also considered some environmental parameters such as temperature, water temperature, depth, salinity and pH. Our results on the environmental parameters analysis did not show significant differences for the study period; besides, salinity data confirmed an oligohaline environment, and the rest of the physico-chemical parameters, varied in accordance with the climatic pattern in the area. We captured a total of 519 fishes, 311 (59.9 %) males and 208 (41.1 %) females; the proportion of males resulted favorable against females throughout the study. The standard length found along the study period showed that the average was higher in males than in females. The trophic spectrum was composed of 13 food items, principally crustaceans, molluscs and fishes; in addition, cannibalism was observed over young individuals during March and April. The most advanced stages of gonadal maturation were recorded from November to March for males, and from November to February in females; generally, the Gonadosomatic index (IGS) recorded the highest values from November to April. The Hepatosomatic Index (IHS) and the Condition Factor (FC) presented an inverse relationship with the Gonadosomatic index (IGS). The fecundity of this species ranged from 96 to 428 oocytes per female. The weight-length relationship by sexes and seasons, showed a higher growth rate for males than for females, and an allometric growth type. The biological and ecological information of O. beta in ALS evidenced the importance of this species and its ecological role in the structure and dynamics of these aquatic communities. This species may be used as a model for future proposals dealing with the management and sustainable use of this ecosystem.

Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic.

Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles-hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta-exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO)-the strongest on record-combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r=-.94) and the Multivariate ENSO Index (MEI) for all years (r=.74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study demonstrates the importance of region-wide collaborations.

Striped marlin (Kajikia audax) diet variability off Cabo San Lucas, B.C.S., Mexico during El Niño–La Niña events

The stomach contents of 1261 striped marlins caught from 2007 to 2010 by the sport-fishing fleet of Cabo San Lucas, Baja California Sur, Mexico, were analysed, taking into account sea surface temperatures estimated using satellite images of the study area and the Oceanic Niño Index (ONI). The analysis allowed the identification of three anomalously cold periods during 2007, 2008 and 2010 and a warm period in 2009. The stomach content results showed 89 different prey items eaten during the study period. Of the specimens captured, 868 (69%) stomachs contained food items. The most important prey items were cephalopods (Dosidicus gigasandArgonautaspp.) and fish (Scomber japonicus,Selar crumenophthalmusandSardinops caeruleus). Despite having a broad trophic spectrum, the striped marlin was classified as a specialist consumer, withBi = 0.03. Based on the diet breadth value and the prey-specific index of relative importance (PSIRI), the jumbo squid,D. gigas, was the main prey species, coinciding with cold periods. On the other hand, the fishesS. caeruleusandS. japonicusshowed the highest PSIRI values during the 2009 warm anomalies. Analysis of similarity showed the formation of four groups in relation to PSIRI values. According to a non-metric multidimensional scaling ordination, these groups were formed with a similarity of 30% and a stress of 0.17. These results demonstrate inter-annual variation in the diet as well as in the availability and abundance of prey items.

Diet and trophic level of the longnose spurdog Squalus blainville (Risso, 1826) in the deep waters of the Aegean Sea

Knowledge of the diet and trophic level of marine predators is essential to develop an understanding of their ecological role in ecosystems. Research conducted on the trophic ecology of the deep-sea sharks is rather limited. The purpose of this study was to examine the diet of the longnose spurdog Squalus blainville, a deep-sea shark categorized as “data deficient” within its distribution range, with respect to sex, maturity, age, season and sampling location. The stomach contents of 211 specimens, captured in the Aegean (off Skyros and the Cyclades Islands) and Cretan Seas, using commercial bottom-trawlers from 2005 to 2012, were analysed. The cumulative prey curve showed that the sample size was adequate to describe the species’ diet. The identified prey items belonged to five major groups: Teleostei, Crustacea, Cephalopoda, Annelida and Phanerogams. Higher diet diversity was observed in females compared to males, in immature individuals compared to mature ones, regardless of sex, and in spring and winter compared to other seasons. Age and sampling location seemed to influence both the diet diversity and trophic spectrum of the species. Feeding intensity based on the vacuity index was not significantly influenced by any of the factors examined, while the stomach filling degree was significantly influenced by all factors, except sex, showing significantly higher values in mature females compared to immature ones, in older individuals, in autumn compared to winter, and a significantly lower value in the Cyclades Islands compared to other locations. Females showed a significant larger mouth length compared to males of the same length, while no between-sex differences were found in gut morphometrics. The estimated fractional trophic level (TROPH=4.41) classified the species as carnivore with a preference for Teleostei and Cephalopoda, confirming its high trophic position.

Parasite burden in decapod crustaceans from the central coast of Chile: is there any association with the relationship with definitive host abundances?

Crustaceans play an important role in parasite life cycles, serving as second intermediate hosts. However, there are scarce parasitological studies in crustaceans from the rocky intertidal habitats, in Chile and around de world. In this study we aimed to record the parasites in decapod crustaceans, compare their parasitic loads between localities and relate them with the abundance of the definitive hosts (fishes and birds). Between July and September 2013, 409 crustacean specimens, corresponding to 16 species, were collected from the rocky intertidal zone of two localities of central Chile (33°S), Las Cruces and Montemar. Of out the sample, 65.5% was parasitized; counting 2,410 metacercariae and 18 nematodes. One group of these metacercariae belonged to the family Opecoelidae; while others corresponded to the family Microphallidae. Nematodes belonged to the family Cystidicolidae. The highest prevalence and abundance of opecoelids were in P. violaceus (96.9%, 13.59 ± 17.50 parasites/crustacean), microphallids were mostly recorded in the crab Petrolisthes tuberculosus (42.3%, 11.08 ± 4.8 parasites/crustacean), while cystidicolids were less prevalent and abundant than digenean at both localities. Parasite loads was affected by body size, locality and species of crustacean hosts. No association was found between parasite loads in these intermediate hosts and the abundance of definitive hosts. The low relationships between parasite loads and host abundances may be due to several reasons, such as a wide trophic spectrum and great capacity of movement, which would not contribute to the parasite transmission and the direct relationship with the definitive host abundances.

Did the giant extinct shark Carcharocles megalodon target small prey? Bite marks on marine mammal remains from the late Miocene of Peru

We report on bite marks incising fossil mammal bones collected from upper Miocene deposits of the Pisco Formation exposed at Aguada de Lomas (southern Peru) and attributed to the giant megatooth shark Carcharocles megalodon. The bitten material includes skull remains referred to small-sized baleen whales as well as fragmentary cetacean and pinniped postcrania. These occurrences, the first in their kind from the Southern Hemisphere, significantly expand the still scarce record of bite marks for C. megalodon; moreover, for the first time a prey (or scavenging item) of C. megalodon is identified at the species level (as Piscobalaena nana, a diminutive member of the extinct mysticete family Cetotheriidae). Due to the fragmentary nature of the studied material, the exact origin of the detected marks (i.e., by scavenging or by active predation) cannot be ascertained. Nevertheless, relying on actualistic observations and size-based considerations, we propose that diminutive mysticetes (e.g., cetotheriids) were some of the target prey of adult C. megalodon, at least along the coast of present-day Peru. C. megalodon is thus here interpreted as an apex predator whose trophic spectrum was focused on relatively small-sized prey. Lastly, we propose a link between the recent collapse of various lineages of diminutive mysticetes (observed around 3Ma) and the extinction of C. megalodon (occurring around the end of the Pliocene).

Сравнение трофических спектров и охотничьих стратегий некоторых крупных паукообразных (Arachnida: Scorpiones, Solifugae, Aranei) в полупустынных биоценозах Гобустана (Восточный Азербайджан)

Сравнение трофических спектров и охотничьих стратегий некоторых крупных паукообразных (Arachnida: Scorpiones, Solifugae, Aranei) в полупустынных биоценозах Гобустана (Восточный Азербайджан)

Food-Web and Ecosystem Structure of the Open-Ocean and Deep-Sea Environments of the Azores, NE Atlantic

The Marine Strategy Framework Directive intends to adopt ecosystem-based management for resources, biodiversity and habitats that puts emphasis on maintaining the health of the ecosystem alongside appropriate human use of the marine environment, for the benefit of current and future generations. Within the overall framework of ecosystem-based management, ecosystem models are tools to evaluate and gain insights in ecosystem properties. The low data availability and complexity of modelling deep-water ecosystems has limited the application of ecosystem models to few deep-water ecosystems. Here, we aim to develop an ecosystem model for the deep-sea and open ocean in the Azores exclusive economic zone with the overarching objective of characterising the food-web and ecosystem structure of the ecosystem. An ecosystem model with 45 functional groups, including a detritus group, two primary producer groups, eight invertebrate groups, 29 fish groups, three marine mammal groups, a turtle and a seabird group was built. Overall data quality measured by the pedigree index was estimated to be higher than the mean value of all published models. Therefore, the model was built with source data of an overall reasonable quality, especially considering the normally low data availability for deep-sea ecosystems. The total biomass (excluding detritus) of the modelled ecosystem for the whole area was calculated as 24.7 t km-². The mean trophic level for the total marine catch of the Azores was estimated to be 3.95, similar to the trophic level of the bathypelagic and medium-size pelagic fish. Trophic levels for the different functional groups were estimated to be similar to those obtained with stable isotopes and stomach contents analyses, with some exceptions on both ends of the trophic spectra. Omnivory indices were in general low, indicating prey speciation for the majority of the groups. Cephalopods, pelagic sharks and toothed whales were identified as groups with key ecological roles in the ecosystem. Due to concerns on the use of ecosystem models with low confidence in exploring management decisions and ecological theories, the current version of this model should only be use with caution until biomass estimates are validated with survey data or the model is fitted to time

<b>Trophic ecology of <i>Loricariichthys melanocheilus</i> Reis & Pereira, 2000 (Siluriformes: Loricariidae) in Ibicuí river, southern Brazil

Aiming to characterize aspects of the trophic ecology of Loricariichthys melanocheilus in the Ibicuí river, bimonthly samples were taken in lotic and lentic ecosystems. Fish were caught and fixed in 10% formalin and dissected for stomach content analysis. Items were identified to the lowest taxonomic level possible. Stomach fullness (SF), repletion index (RI) and intestinal quotient (IQ) were estimated. Diet was assessed by the frequency of occurrence and the volumetric method, combined to obtain a Alimentary index. Feeding activity was analyzed with mean values of SF, RI and vacuity index (VI), which represents the percentage of empty stomachs. These parameters were compared seasonally, spatially, and according to the circadian rhythm. The main items in the trophic spectrum of L. melanocheilus were detritus, sediment, plant organic matter, nematodes, micro crustaceans (Copepoda, Cladocera) and insects (Diptera, Trichoptera, Ephemeroptera and Odonata). No environmental or seasonal variations were found for the consumed items. Feeding activity showed seasonal and environmental variations according to RI but did not significantly change according to SF. The IQ was 1.51, and showed seasonal variations, indicating changes in the diet.

Trophic associations and specialization of phytophagous beetles (Coleoptera: Chrysomeloidea, Curculionoidea) in the east of the Russian Plain

Data on the trophic associations of beetles with plants in the east of the Russian Plain are summarized and comparative analysis of host specialization of different groups of phytophagous beetles is performed. In terms of the width of the regional trophic spectrum, monophages and narrow oligophages prevail among the Curculionoidea as a whole and in the families Curculionidae and Apionidae in particular, while moderate and broad oligophages prevail in the Chrysomeloidea and in the family Chrysomelidae. Two-thirds of the regional fauna (66%) of Curculionoidea are closely associated with plants of one genus; by contrast, in Chrysomeloidea almost 40% of the species can develop on plants from different genera of one family, the fraction of the narrowly specialized forms comprising only 43%. The higher level of trophic specialization of weevils (Curculionidae, Apionidae) and seed beetles (Bruchidae), as compared to leaf beetles (Chrysomelidae), is probably due to the larval endophagy of most species of these families. Analysis of the distribution of beetles over host plants has shown that the specialized forms are associated with plants of 65 families (about 60% of the regional flora in the east of the Russian Plain). Distribution of beetles over plant families is very non-uniform. Most of the specialized forms (78%) are associated with plants of 15 families, three of which (Asteraceae, Fabaceae, and Brassicaceae) include hosts of more than onethird of the beetle species (37%). Monophages and narrow oligophages are recorded on 201 genera of plants from 59 families. Polyphagous species are recorded on plants of 58 families. The specific features of the distribution of phytophagous beetles over host plants (as compared to other insects) is a high fraction of species developing on coenophobes (particularly those of the family Brassicaceae) typical of the pioneer stages of successions with sparse herbaceous cover, and a small number of species associated with grasses and sedges. These features are most conspicuous in the fauna of Curculionidae.

Feeding of Characidium rachovii (Characiformes: Crenuchidae) and Pyrrhulina australis (Characiformes: Lebiasinidae) in shallow lakes of Corrientes, Argentina

Fishes display diverse feeding strategies that may undergo modifications through ontogeny or seasonally with ecological implications in the food webs. Even though the significance of fishes as top predators is recognized, the diet of many of them is still scarcely known; especially in fish that inhabit shallow lakes densely vegetated. The aim of this study was to investigate the diet of Characidium rachovii and Pyrrhulina australis of different size classes (I, II and III); during winter and summer, and estimate their trophic niche breadth. The field work was carried out in two shallow lakes fed by rain (Soto and Pampin lake, Corrientes province), from July 2011 to August 2012. The stomach contents of 104 individuals of C. rachovii and 91 specimens of P. australis were examined. Accumulation curve showed that the number of analyzed stomachs was representative for both species. Twenty three food items for C. rachovii and twenty eight for P. australis were recognized in the gut contents. According to the index of relative importance (IRI), both species feed preferably on cladocerans and midges (Chironomidae), and both species showed a large overlap in their diets (85 %), according to Morisita index. However the diversity of food items and the trophic niche breadth of P. australis (1D = 8.86; B = 4.76) were higher than C. rachovii (1D = 3.37; B = 2.25). Significant differences were observed in the diet of three sizes of P. australis (χ2, p < 0.01) and between the sizes I and III of C. rachovii (χ2, p = 0.03). In both species the diversity of food items increased with increasing their size. Between seasons, the diet differences were significant for both species (χ2, p < 0.0001). The high feeding overlap indicates that both species mostly use the same resources. Notwithstanding this, both the number of food items as the diversity and breadth of the trophic niche, suggest that these species use different feeding strategies, C. rachovii showed a trend towards specialization in microcrustacean consumption; while P. australis exhibited a broader trophic spectrum, incorporating insects from littoral areas and from the terrestrial community. The loss of the trophic dominant resource, by increasing urbanization on the margin of the studied shallow lakes, could lead to increased competition, due to the wide diet overlap in both species.

Effects of season, sex and age on the diet of Homonota fasciata (Squamata, Phyllodactylidae) from Monte region of Argentina

Abstract This study aimed to investigate the diet of the gecko Homonota fasciata (Duméril &amp; Bibron, 1836) in a population from Monte of San Juan Province, Argentina, and to analyze possible temporal, sexual, and ontogenetic variations in feeding behavior. We determined the total volume, number, and occurrence frequency of each prey item and calculated the relative importance indexes. We also assessed trophic diversity and trophic equity. Homonota fasciata had a generalist and diverse diet based on arthropods, including insects and arachnids. Individuals adopted a passive 'sit and wait' foraging strategy. There were seasonal-, sex-, and age-related variations in the trophic spectra. The results of this study provide a valuable contribution to our understanding of the biology of this species, with implications for the establishment of management guidelines both for the species and its habitat.

Structure and dynamics of the trophic spectrum of the American mink (Neovison vison) in the Southern Urals

The peculiarities of feeding of the American mink (Neovison vison) near lakes and mountain rivers of the Southern Urals are studied. Significant differences are shown between structure and dynamics of the mink diet near lakes and mountain rivers. The diet of minks near mountain rivers depends on the abundance of small-sized mammals inhabited at the banks, which is determined by properties of the hydrological regime in each season.

Quantile regression analysis as a predictive tool for lake macroinvertebrate biodiversity

The Water Framework Directive introduced in Europe major changes to improve the management of water resources. This study aims to highlight some of the potential implications of its implementation for lake water monitoring in Italy. A Life+ project was launched to plan the first monitoring of lake macroinvertebrates standardized at the national level.Quantile regression analysis was used to explain different metrics of diversity describing macroinvertebrate communities in response to twenty-one variables representing chemical, physical and morphological characteristics of the environment. Nine lakes located in two Italian regions (Piedmont and Sardinia) were analyzed covering a wide trophic spectrum, from oligotrophy to hyper-eutrophy. The lakes were sampled following the national standardized protocol with samples covering the three recognized lake zones: littoral, sublittoral, profundal.The studied lakes had high chemical variability with conductivity ranging between 53 and 561μS/cm, pH between 6.5 and 9.1, and alkalinity between 14 and 398mg/l. The bottom sediments were characterized by fine sand (range 51–99%), followed by silt (1–35%) and clay (0–28%). When the Lake Habitat Survey was also applied to these lakes, its synthetic indices (LHMS, Lake Habitat Modification Score and LHQA, Lake Habitat Quality Assessment) produced higher values in natural lakes (mean values±SD: LHMS=26±7, LHQA=57±3) than in the reservoirs (LHMS=22±4, LHQA=52±6). In all lakes, macroinvertebrates mainly consisted of chironomids and oligochaetes characterized by relative abundances up to 80% and >90%, respectively.Using quantile regression to evaluate limiting responses, only two variables, namely sampling depth and oxygen percent saturation (oxygen content), resulted the ones that best explained all the analyzed metrics of diversity of the macroinvertebrate communities. Depth and oxygen were then used to suggest synthetic models describing the various metrics of potential community diversity. These models can help the environmental agencies responsible for monitoring at the national level in distinguishing entire lakes or part of them with high biodiversity from those in altered conditions and then address remediation efforts toward the water bodies with the most critical conditions. Such approach could also be used to optimize the sampling procedures for the application of the Benthic Quality Index for lakes currently adopted at national level.

Значение минерального питания в жизни кавказской серны в Сочинском национальном парке

The trophic spectrum of wild hoofed animals Caucasus, mineral nutrition is important. As an experiment, 67 quarter forestry Adler, Sochi National Park, near the habitat of the сaucasian chamois was laid artificial source of salt. Materials for the study of the value of mineral nutrition of wild animals were the photos produced by the installation of the pilot area of automatic photo-recorder. Gathered for the annual period photographs were processed and systematized. The data allowed analyzing the dynamics of artificial source of salt visit.