Community Structure of Coastal Fishes in Relation to Heavily Impacted Human Modified Habitats

Diversity and community structure of coastal fishes were compared between reforested mangrove and reclaimed sandy habitats at Pasir Ris, in the eastern part of Singapore. Both habitats supported a total of 91 species, but a single species, Ambassis kopsii dominated in abundance. Mean fish density was significantly higher at the reclaimed sandy shore than the reforested mangrove, but the reforested mangrove habitat yielded higher diversity. Apart from A. kopsii, abundant species in the mangroves included Ambassis interrupta, Thryssa hamiltonii, Acentrogobius sp., Scatophagus argus and Arius sagor. Anodontostoma chacunda, Acentrogobius sp., Leiognathus decorus, Sillago sihama and Stolephorus sp. were abundant in the reclaimed sandy habitat. Both habitats exhibited a higher mean density and average species richness during high tide. Several species from the family Gobiidae dominated the catch during low tide while pelagic fishes were most abundant during high tide. Diel variation showed significantly higher density during the day than at night, a result that contrasts to similar studies elsewhere. However, species richness showed no significant variation between day and night catches. Interaction between combined factors of time of the day and tidal height on fish density and average species richness was significantly different. The results indicated both habitat types to be important fish nurseries.     

Feeding ecology of two sillaginid fishes and trophic interrelations with other co-existing species in the southern part of South China Sea

Feeding ecology of Sillago sihama and Sillago ingenuua and interrelationship with other 15 fish species, including Stolephorus commersonii, Escualosa thoracata, Lutjanus russelli, Terapon puta, Ambassis kopsii, Ambassis vachellii, Dendrophysa russelli, Gerres filamentosus, Leiognathus decorus, Leiognathus splendens, Leiognathus equulus, Thryssa hamiltonii, Carangoides praeustus, Lethrinus lentjan, and Pomadasys maculatum, utilizing coastal waters off the southern part of the South China Sea were investigated. Dietary contents from 4308 guts of those species collected during July 2003–May 2005 were examined. They were significantly grouped, based on similarity coefficient, into five feeding clusters (P < 0.01). Of these, most of the diets were dominated by calanoid copepods, shrimps, polychaetes and gammarid amphipods. Comparative study on two sillaginid species showed that both Sillago sihama and Sillago ingenuua were carnivores fed mainly on polychaetes and other benthic organisms. Dietary ontogenetic change of Sillago sihama was very distinctive where small sized classes started feeding mainly on calanoid copepods before changing almost completely to polychaetes. The two species applied both sharing and partitioning strategies for food, depending on size classes, to live with each other.     

The role of floods in the lives of fish-eating birds: predator loss or benefit?

Floods accompanied by high flow and high water turbidity are usually believed to cause problems to fish-eating birds and mammals searching visually for their prey. In the present study the diets of breeding kingfishers were studied during the normal river situation and during a long-lasting flood event with respect to diet composition, size of fish prey and food diversity index. During the normal situation (flow 1.75 m³ s^?1, Secchi disc depth 0.5–1 m), the diet of a kingfisher was dominated by benthic fish species (52.9% by numbers, 63.9% by weight), the average size of fish taken was 6.5 cm L _T and 3.0 g and the food diversity index reached its lowest value (1.57). In contrast, during the long-lasting flood event (flow 5–28 m³ s^?1, Secchi disc depth 0.03–0.4 m) the diet of the kingfisher was dominated by sub-surface fish species (72.4% by numbers, 76.1% by weight) and both the average size of fish taken (7.4 cm L _T and 3.7 g) and the food diversity index (1.83) increased significantly. The birds provided their nestlings with lower numbers of fish of larger sizes, which resulted in very similar weights of the young birds prior to fledging when the flood and normal situations were compared. This study provides evidence that in different foraging conditions the kingfishers adopt different foraging strategies to maintain their high breeding success.     

Dietary overlap among early juvenile stages in an Antarctic notothenioid fish assemblage at Potter Cove,South Shetland Islands

To date, studies of food overlap in Antarctic fish have been performed on a mixture of late juvenile and adult stages, leaving the young immature specimens (TL ≤ 10 cm) practically unexplored. We studied diet overlap and potential competition among early juvenile individuals in a coastal notothenioid community at Potter Cove, by analysing the stomach contents of 225 fish of 5 species collected in the summer of 2009–2010. We used frequency of occurrence (F %) and the coefficient “Q” for diet evaluation and the method of Tyler and the similarity index “S” for food overlap. Amphipods of the suborder Gammaridea were the main (Q > 2.900) and most frequent (% F) prey for all species, although Notothenia coriiceps also consumed gastropods of the family Littorinidae, mostly Laevilitorina antarctica. Secondary prey were algae for Notothenia rossii and N. coriiceps, calanoid (pelagic) and harpacticoid (benthic) copepods for Trematomus newnesi and the latter copepods and isopods of the family Munnidae for Lepidonotothen nudifrons. The reoccurrence of prey among fish species was 39.6 % and food overlap between 90 % of species pairs was under 58 %. Because similarly low values of diet overlap were reported for intermediate/advanced juveniles and adults of the same species at the same site, we conclude that there is no difference in the degree of interspecific food overlap and therefore potential competition between the immature and mature fraction of the fish community. Food competition is avoided by resource partitioning along a depth gradient or by different prey species.     

Length-weight relationships of eight fish from seagrass meadows in Wenchang,China

The length-weight relationships (LWRs) were studied for eight seagrass fish from Wenchang, China, using gill nets (150*1 m, mesh size 0.5 cm), including Gerres oblongus, Ambassis kopsii, Halichoeres nigrescens, Sillago aeolus, Yongeichthys criniger, Oxyurichthys tentacularis, Lethrinus haematopterus and Hypoatherina tsurugae, in November 2017, March and August 2018. Results suggest that mean LWR parameters b for these eight seagrass fish varied from 2.801 for L. haematopterus to 3.640 for A. kopsii, and r² valued from .950 for L. haematopterus to 0.993 for H. nigrescens. This study will help us to better understand the ecological parameters these seagrass fish.     

Redescriptions ofGerres baconensis (Evermann & Seale, 1907),G. equulus Temminck & Schlegel, 1844 andG. oyena (Forsskål, 1775), included in the “G. oyena complex”, with notes on other related species (Perciformes: Gerreidae)

The gerreid species,Gerres baconensis (Evermann &; Seale),G. equulus Temminck &; Schlegel andG. oyena (Forsskål), were re-assessed as valid following examination of their holotypes and other specimens, and included in the “G. oyena complex”.Gerres haconensis is currently known only from Bacon, Luzon Island, Philippines and the Ogasawara (=Bonin) Islands, Japan, andG. equulus only from southern Japan (except Ryukyu Islands) and southern Korea.Gerres oyena is widely distributed in the Indo-West Pacific (in Japan, only from the Ryukyu Islands).Gerres baconensis differs from bothG. equulus andG. oyena in having higher counts of both the pored lateral line scales (39–42 vs 35–41 in the latter two species) and the lower gill raker series (8 or 9 vs. usually 7). A U-shaped premaxillary groove, formed on the dorsum of the forehead by the long ascending processes of the premaxillae, is scaleless inG. equulus andG. oyena, whereas it is fully scaled just behind the level of the posterior nostrils inG. baconensis over ca. 160 mm in standard length (SL) (partially scaled in specimens of ca. 100 mm SL).Gerres equulus differs fromG. oyena in having the posterior margin of the maxilla not extending beyond a vertical through the anterior margin of the inner dermal eye opening, shorter second dorsal and anal fin spines (means 18.5% and 8.5% of SL, respectively vs. 21.2% and 10.3% of SL), lower body depth at first anal fin spine base (27.0% vs. 29.6% of SL) and dorsomedial U-shaped groove scaleles throughout life (vs. tiny squamation anteriorly in specimens over ca. 130 mm SL). OtherGerres species of uncertain status and/or related species are discussed.     

The diet of the subantarctic fur seal Arctocephalus tropicalis at Marion Island

Scats of subantarctic fur seals Arctocephalus tropicalis at Marion Island were collected from 1996 to 2,000, to examine temporal variability in the diet, factors affecting the variability and how the diet differed from that of the Antarctic fur seal A. gazella in the same period. For A. tropicalis, 19 prey species, of which 18 were fish and one a cephalopod, were identified in 213 scats. Fish were the main prey, occurring in 98.1 % of scats, whereas the cephalopod was present in only 1.4 % of scats. Amongst fish species, Myctophidae were most abundant, with Gymnoscopelus piabilis, G. fraseri and Electrona carlsbergi being the commonest prey items. Other fish families present in the diet in small numbers were Channichthyidae, Paralepididae, Nototheniidae, Microstomatidae and Notosudidae. Fish eaten ranged in size from Protomyctophum bolini and Krefftichthys anderssoni of standard length (SL) 25 mm to a single Dissostichus eleginoides of SL 249 mm. Differences in the diet existed between summer and winter. However, prey type accounted for most variability in the diet. In previous studies based on scats, a dominance of fish in the diet of A. tropicalis was also found at Possession Island (Iles Crozet), Amsterdam Island and Macquarie Island, but the dominant prey species differed between the various localities, also suggesting that prey availability is a major determinant of diet. At Marion Island, from 1996 to 2000 the diet of A. gazella comprised similar prey to that of A. tropicalis, but the proportional contribution of prey types differed in instances.     

A survey of coccidian infections of freshwater fishes of Peninsular Malaysia,with descriptions of three species of Goussia Labbé, 1896 (Apicomplexa: Eimeriidae)

Ninety-five specimens of 14 freshwater fish species from small streams in the Kuala Terengganu district and the Lake Kenyir Reservoir, Malaysia, were surveyed for coccidian infections. Six fish species proved to be infected with apicomplexans belonging to the genus Goussia. In all of these fishes Goussia species were found in unsporulated and semisporulated stages. Oöcysts of four species inhabiting the intestinal epithelium became sporulated in tap-water within 24 hours. In two fish species sporulation failed and only unsporulated oöcysts were recorded in the intestine. Three of the intestinal species finishing sporulation proved to be new to science and were described as Goussia malayensis n. sp., G. bettae n. sp. and G. pogonognathi n. sp. from Apocheilus panchax, Betta splendens and Hemirhamphodon pogonognatus, respectively. The fourth species, found in Trichogaster pectoralis, was identified as G. trichogasteri Székely &; Molnár, 1992, a species known from aquarium-cultured T. trichopterus.     

Effect of dietary fish meal replacement by red algae, Gracilaria arcuata, on growth performance and body composition of Nile tilapia Oreochromis niloticus

A 12-week long feeding experiment was initiated to evaluate the effect of dietary supplementation of red algae, Gracilaria arcuata, on the growth performance, feed utilization and body composition of Nile tilapia Oreochromis niloticus (Linnaeus, 1758). The fish were fed with an algae-free control diet (C) and three experimental diets which replaced conventional fish meal with varying levels of dried G. arcuata (20%, 40% and 60%, represented as G20, G40 and G60, respectively). The growth parameters of final weight (FW), weight gain (WG), percentage of weight gain (WG%), daily growth rate (DGR) and specific growth rate (SGR) were significantly reduced (P < 0.05) at all levels of algae incorporation compared to the control diet. Moreover, the negative impact of Gracilaria meal on the growth performance of Nile tilapia increased as the proportion of algae in the diet increased, with fish on diet G20 exhibiting a significantly higher growth performance than the fish on either of the G40 and G60 diets. On the other hand, the feed utilization parameters feed conversion ratio (FCR) and protein efficiency ratio (PER) did not show significant differences between the fish in the control group and those on diet G20, although poorer FCR and PER outcomes were achieved in the case of fish on diet G60. The content of moisture, protein and ash in muscle and carcass increased as the proportion of Gracilaria meal in the diets increased, but the reverse was true for lipid level. These results indicate that incorporation of less than 20% red algae, Gracilaria arcuata, could be feasible in the diet of Nile tilapia and further studies are recommended to optimize the level of algae to improve growth performance.     

Diet composition of the electric eel Electrophorus voltai (Pisces: Gymnotidae) in the Brazilian Amazon region

The diet composition of the electric eel Electrophorus voltai was studied in specimens collected from the River Jari, state of Amapá, eastern Amazon region, Brazil. Analysis on their stomach contents revealed that fish, especially Megalechis thoracata, were the most frequent prey item, whereas arthropods and plant material were the least frequent intakes. This is the first stomach content analysis on E. voltai, and it corroborates that electric eel species are piscivorous.     

The feeding habits of Sargochromis Codringtonii in Lake Kariba, Zimbabwe

The food of adult Sargochromis codringtonii in Lake Kariba was dominated by prosobranch snails with pulmonate snails forming an insignificant dietary component. S. codringtonii does not show particular preference for any snail species, feeding on those species that are readily available. Morphometrical analysis of the feeding structures of S. codringtonii showed that the fish is well adapted to handling a molluscivorous diet. The pharyngeal jaws with their flat crowned teeth are well adapted to crushing molluscs. The daily food consumption rate of S. codringtonii was estimated over different seasons. Estimates of food consumption indicate that the fish consumed 13.96% of their dry body weight per day in summer falling to 4.46% in winter. The low consumption of pulmonate snails suggests that S. codringtonii can not be a successful biological control agent against the vectors of schistosomiasis.     

Dietary Administration of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> Enhanced Growth Performance and Innate Immune Response of Siberian Sturgeon, <Emphasis Type="Italic">Acipenser baerii</Emphasis>

We investigated the effects of Lactobacillus plantarum used as a dietary supplement on the growth performance and innate immune response in juvenile Siberian sturgeon Acipenser baerii. Juvenile fish (14.6 ± 2.3 g) were fed three experimental diets prepared by supplementing a basal diet with L. plantarum at different concentrations [1 × 10⁷, 1 × 10⁸ and 1 × 10⁹ colony-forming units (cfu) g^?1] and a control (non-supplemented basal) diet for 8 weeks. Growth performance indices were increased in fish fed the 1 × 10⁸ cfu g^?1 L. plantarum diet compared to the other groups. There was an increased innate immune response in fish fed the experimental diets. The highest levels of lysozyme activity, total immunoglobulin (IgM) and complement component 3 (C3) were observed in fish fed the diet containing L. plantarum at a concentration of 1 × 10⁸ cfu g^?1, but there was no significant difference in the level of complement component 4 (C4) in fish fed the experimental diets or the control diet. The present study underlying some positive effects (growth performance and immune indices) of dietary administration of L. plantarum at a concentration of 1 × 10⁸ cfu g^?1 in the Siberian sturgeon.     

The importance of zooplankton in the diets of three native fish species in floodplain waterholes of a dryland river,the Macintyre River,Australia

The zooplankton of freshwater systems has been recognized as an important energy resource for fish of small body size that, in turn, provide energy to piscivorous fish consumers higher up the food web. This study evaluates the importance of zooplankton to the diets of three species of fish living in floodplain waterholes of an Australian dryland river. The species selected for study represent different trophic categories in waterhole food webs: Ambassis agassizii is a microcarnivore, Leiopotherapon unicolor is an omnivore, and Nematalosa erebi is a detritivore. Dietary differences among size classes of each species were also evaluated to understand possible ontogenetic shifts in zooplankton consumption. Ambassis agassizii fed primarily on zooplankton (99.9%, made up mostly of 81.6% Calanoida and 17.4% Moinidae), regardless of the size of individual fish. Leiopotherapon unicolor fed on zooplankton (47%, mostly Daphniidae and Moinidae) and aquatic insects (46.7%). Smaller individuals of Leiopotherapon unicolor (30–49 mm TL—total length) were responsible for 36.1% of the plankton consumed by the species. Nematalosa erebi fed on detritus (84.6%) with zooplankton (Calanoida, Moinidae, and Cyclopoida) contributing only 13.7% of the mean diet. Smaller individuals (40–69 mm TL) were responsible for 98% of the plankton consumed by Nematalosa erebi, and individuals of 40–49 mm (TL) fed exclusively on zooplankton (53.8% Moinidae and 46.2% Calanoida). Although the three fish species had different diets, reflecting differences in species-specific and ontogenetic morphological and behavioral characteristics, zooplankton formed the basis of the diet of all species when young. These results confirm the importance of zooplankton as a major food resource for three fish species and smaller size classes of these species in floodplain waterholes of the Macintyre River, Australia. Guest editors: U. M. Azeiteiro, I. Jenkinson & M. J. Pereira Plankton Studies     

长江口和杭州湾凤鲚胃含物与海洋浮游动物的种类组成比较

2009年6月—8月期间在长江口及杭州湾水域收集了1355尾的凤鲚（Coilia mystus）标本,对其胃含物进行分析,期间采用出现频率（F）、个数百分比（N）、重量百分比（W）、相对重要性指标（IRI）、优势度（Y）公式计算,并进行种类的相似性分析,同步采集了取样点附近的浮游动物,比较了凤鲚胃含物食谱与该海域浮游动物种类组成。结果表明：河口性的长额刺糠虾IRI 为703.25,%IRI为62.94%,远远超过其他种类,甚至超过任何一个桡足类优势种,因而是凤鲚食谱中的最重要的种类。凤鲚摄食的其他主要种类包括：火腿许水蚤（Schmackeria poplesia）（IRI = 261.04）,虫肢歪水蚤（Tortanus vermiculus）（IRI = 107.53）、真刺唇角水蚤（Labidocera euchaeta）（IRI = 27.27）。以上四种浮游动物重要性合计%IRI为98.36%。在主要食物种类占绝对优势。因而是凤鲚饵料中最重要的优势种。种类组成相似性分析结果显示：胃含物和海域浮游动物之间的相似度值大致在0.363—0.365之间;而两者桡足类之间的相似值在0.521—0.575之间。推测凤鲚对个体较小的桡足类摄食方法是过滤性摄食,对种类的选择性较低。而对个体较大的糠虾则是有选择性追逐摄食。     

Diet Composition and Intensity of Feeding of Tenualosa ilisha (Hamilton, 1822) Occurring in the Northern Bay of Bengal,India

Feeding intensity and diet composition of Hilsa Shad (Tenualosa ilisha) from Northern Bay of Bengal were studied between June 2010 and March 2011. The stomach contents of 320 fishes were analyzed from the northern part of the Bay of Bengal to understand the food items of this species. The major constituents of food are organic debris (26.06 ± 5.19 % SD), diatoms (31.22 ± 11.97 % SD), other algae (12.41 ± 2.62 % SD), and crustaceans (3.50 ± 1.28 % SD). The most abundant species of diatoms were Coscinodiscus, Pleurosigma, Bacillaria, Nitzschia, Biddulphia, Diatoma and Asterionella. The stomach of Hilsa was found to be almost empty during June to October while it was almost full during November to March. Significant positive correlation among feeding intensity, chlorophyll-A concentration and salinity of the ambient water indicated that feeding in T. ilisha is influenced by a number of factors. Strong positive correlation between percentage occurrence of diatoms and intensity of feeding indicated their preference for diatom–food.     

Gutsy genetics: identification of digested piscine prey items in the stomach contents of sympatric native and introduced warmwater catfishes via DNA barcoding

A major focus of ecology is understanding trophic relationships and energy flows in natural systems, associated food web dynamics and changes in food webs due to introduced species. Predator-prey interactions are often assessed by examining stomach contents. However, partially digested remains may be difficult to accurately identify by traditional visual analysis. Here we evaluate the effectiveness of DNA barcoding to identify digested piscine prey remains in invasive Blue Catfish Ictalurus furcatus, non-native, but established Channel Catfish Ictalurus punctatus and native White Catfish Ameiurus catus from Chesapeake Bay, USA. Stomach contents were examined and piscine prey items were scored as lightly digested, moderately digested or severely digested. A 652 base pair region of the cytochrome c oxidase subunit I (COI-5P) mitochondrial DNA gene was sequenced for each prey item. Edited barcode sequences were compared to locally-caught and validated reference sequences in BOLD (Barcode of Life Database). A large majority of prey items were sufficiently digested to limit morphological identification (9.4 % to species and an additional 12.1 % to family). However, overall barcoding success was high (90.3 %) with little difference among the digestion classifications. Combining morphological and genetic identifications, we classified 91.6 % of fish prey items to species. Twenty-three fish species were identified, including species undergoing active restoration efforts (e.g., Alosa spp.) and commercially important species, e.g., Striped Bass Morone saxatilis, White Perch Morone americana, American Eel Anguilla rostrata and Menhaden Brevoortia tyrannus. We found DNA barcoding highly successful at identifying all but the most heavily degraded prey items and to be an efficient and effective method for obtaining diet information to strengthen the resolution of trophic analyses including diet comparisons among sympatric native and non-native predators.     

Seasonal variation of food and feeding in burrowing goby <Emphasis Type="Italic">Parapocryptes serperaster</Emphasis> (Gobiidae) at different body sizes

Diet composition and feeding habits of the burrowing fish Parapocryptes serperaster were investigated on different fish sizes across dry and wet seasons in the Mekong Delta, Vietnam. The gut length was positively related to fish length; the gut length was 1.57 ± 0.30 times the total length, which is in the range for omnivore (1–3). Detritus, algae and copepods were the main food items in the foregut. The diet composition showed seasonal and intraspecific variations in all fish sizes. The diet diversity varied with fish size and the dry-wet season pattern, and small fish had a higher diet diversity than large fish. The diet evenness index and Costello graphic analysis indicate that this goby is a generalist feeder and feeds mainly on detritus, followed by diatoms, and could obtain food from the bottom and the water column. The feeding intensity of P. serperaster was higher in the wet season than in the dry season, but was not significantly affected by fish size. The P. serperaster fed on Navicula spp. in the wet season, but on Nitzschia spp. in the dry season. The understanding of food and feeding habits of P. serperaster contributes to our knowledge on feeding adaptation of small-bodied bottom-dwelling gobies to the mud flat habitats in tropical monsoonal regions.     

Distribution and diet of demersal Arctic Cod, <Emphasis Type="Italic">Boreogadus saida</Emphasis>, in relation to habitat characteristics in the Canadian Beaufort Sea

Arctic Cod (Boreogadus saida) occur throughout the circumpolar north; however, their distributions at localized scales are not well understood. The seasonal habitat associations and diet preferences across life-history stages of this keystone species are also poorly known, thereby impeding effective regulatory efforts in support of conservation objectives. The distribution of Arctic Cod in the Canadian Beaufort Sea was assessed using bottom trawling in shelf and slope habitats between 20 and 1000 m depths. Highest catch biomasses occurred at 350 and 500 m depth slope stations, coinciding with >0 °C temperatures in the Pacific–Atlantic thermohalocline and Atlantic water mass. Calanus glacialis, Calanus hyperboreus, Themisto libellula, and Themisto abyssorum were identified as key prey species in the diet of Arctic Cod, comprising approximately 86 % of total biomass in guts. Hierarchical cluster analysis with a SIMPROF test identified five statistically significant (p < 0.05) diet groups among gut samples. Arctic Cod shifted from a primarily Calanus diet at shelf stations (<200 m depth) to a Themisto diet in slope habitats (>200 m depth) coinciding with an associated increase in fish standard length with depth. Smaller Arctic Cod fed primarily on Calanus copepods and larger Arctic Cod fed primarily on the larger Themisto species. The habitat and diet associations presented here will inform knowledge of structural and functional relationships in Arctic marine ecosystems, aid in mitigation and conservation efforts, and will enhance our ability to predict the effects of climate change on the local spatial and depth associations of this pivotal marine fish.     

Continued feeding on <Emphasis Type="Italic">Diporeia</Emphasis> by deepwater sculpin in Lake Huron

Monitoring changes in diets of fish is essential to understanding how food web dynamics respond to changes in native prey abundances. In the Great Lakes, Diporeia, a benthic macroinvertebrate and primary food of native benthivores, declined following the introduction of invasive Dreissena mussels and these changes were reflected in fish diets. We examined the diets of deepwater sculpin Myoxocephalus thompsonii collected in bottom trawls during 2010–2014 in the main basin of Lake Huron, and compared these results to an earlier diet study (2003–2005) to assess if their diets have continued to change after a prolonged period of Dreissena mussel invasion and declined Diporeia densities. Diporeia, Mysis, Bythotrephes, and Chironomidae were consumed regularly and other diet items included ostracods, copepods, sphaerid clams, and fish eggs. The prey-specific index of relative importance calculated for each prey group indicated that Mysis importance increased at shallow (≤55 m) and mid (64–73 m) depths, while Diporeia importance increased offshore (≥82 m). The average number of Diporeia consumed per fish increased by 10.0% and Mysis decreased by 7.5%, while the frequency of occurrence of Diporeia and Mysis remained comparable between time periods. The weight of adult deepwater sculpin (80 mm and 100 mm TL bins) increased between time periods; however, the change in weight was only significant for the 80 mm TL group (p?<?0.01). Given the historical importance of Diporeia in the Great Lakes, the examination of deepwater sculpin diets provides unique insight into the trophic dynamics of the benthic community in Lake Huron.     

Trophic Segregation of Small Carnivorans (Carnivora: Mustelidae and Mephitidae) from the Southern Cone of South America

Remarkable adaptations in the Carnivora have evolved as a way of dealing with feeding competition, accentuating hypocarnivorous or hypercarnivorous morphotypes. The Carnivora is a highly successful order with 47 living species in South America. Their history in South America is recent, and includes few lineages that arrived before the Panamanian bridge was completed (procyonids), and others that arrived later (felids, mephitids). Here, we evaluated the trophic segregation of small carnivorans (Conepatus chinga, Galictus cuja, Lontra provocax, Lyncodon patagonicus, and the introduced Neovison vison) from southern South America, using a geometric morphometric approach, i.e., Principal Component and Canonical Variate Analysis, to study shape variations and t-tests to study size variation. We also performed Canonical Phylogenetic Ordination to study the association between shape, size, diet, and phylogeny. We identified C. chinga as the most hypocarnivorous member of the guild, G. cuja, L. patagonicus, and N. vison as hypercarnivores, with L. provocax in an intermediate position. Semiaquatic habits segregate Lontra provocax, and partially N. vison, from other species. Significant differences in size were observed between all species pairs, except C. chinga and N. vison. Phylogeny accounts for a very important part of morphological variance, with cladogenetic events between mustelids and mephitids responsible for almost 55 % of it. The small carnivoran guild of southern South America is represented by species adapted to different feeding strategies, with C. chinga and L. provocax preying mainly on invertebrates, G. cuja and L. patagonicus specifically on small vertebrates, and the non-native N. vison with a highly diverse diet.