Bruinvis verhongert soms in zee vol vis : tien jaar onderzoek naar menu zeezoogdier
Leopold, Mardik - \ 2016
phocoena - animal behaviour - animal ecology - population ecology - feeding behaviour - feeding ecology - marine biology
Avoiding Competition? Site Use, Diet and Foraging Behaviours in Two Similarly Sized Geese Wintering in China
Zhao, Meijuan ; Cao, Lei ; Klaassen, Marcel ; Zhang, Yong ; Fox, Anthony D. - \ 2015
Ardea 103 (2015)1. - ISSN 0373-2266 - p. 27 - 38.
Anser albifrons - Anser fabalis - dietary composition - feeding ecology - interspecific competition
Competition may occur when two species with similar feeding ecologies exploit the same limited resources in time and space. In recent years, the Eastern Tundra Bean Goose Anser fabalis serrirostris and Greater White-fronted Goose Anser albifrons frontalis have increased in wintering numbers at Shengjin Lake, China. To examine the potential for coexistence and possible avoidance strategies, we studied (1) their habitat use, (2) foraging behaviours and (3) diets of birds foraging in mixed- and single-species flocks. Both species extensively exploited sedge meadows, where they showed considerable overlap in spatial distribution and diet. The percentage feeding time and diet of both species were unaffected by the presence of the other. Greater White-fronted Geese appeared diurnal sedge meadow specialists, almost never feeding in other habitats. Eastern Tundra Bean Geese were less selective, exploiting other habitats, which they increasingly exploited at night in mid-winter. The use of alternative habitats and night feeding may have avoided interspecific competition. While the specialised feeding ecology of Greater White-fronted Geese may make them particularly vulnerable to loss of sedge meadow habitat, Eastern Tundra Bean Geese may be able to adjust because of their use of alternative habitats and a less restricted diet.
The role of structuring benthos for juvenile flatfish
Rabaut, M. ; Audfroid Calderon, M. ; Moortel, L. van de; Dalfsen, J.A. van; Vincx, M. ; Degraer, S. ; Desroy, N. - \ 2013
Journal of Sea Research 84 (2013). - ISSN 1385-1101 - p. 70 - 76.
plaice pleuronectes-platessa - polychaete lanice-conchilega - sole solea-solea - platichthys-flesus - feeding ecology - habitat suitability - l. - community - flounder - growth
Within coastal nurseries, the distribution of juvenile flatfish may depend on small-scale habitat variability. The presence of ecosystem engineers is known to have important impacts in coastal sediments. Lanice conchilega is a well-known marine ecosystem engineer of shallow soft bottom ecosystems, shaping the macrobenthic community and attracting flatfish. The present study examines the relation between juvenile flatfish and L. conchilega reefs through two experiments. In a field experiment in the Dutch part of the North Sea, the benthic habitat is evaluated by comparing relative differences in numbers of juvenile flatfish between ecosystem engineered habitats and adjacent bare sand (i.e. non-ecosystem engineered) habitats. The hypothetical shelter seeking behaviour was further examined using stomach content analyses. Results show that juvenile plaice Pleuronectes platessa was the dominant species within the tube worm habitat and the species selects specifically for this biogenic habitat. This selection was explained as feeding behaviour. In a complementary laboratory study, food was excluded and the shelter function of the ecosystem engineered habitat was investigated. This experiment quantifies the selection for this habitat by juveniles of the common sole Solea solea. Results from the flume experiment, manipulating the number of tube worms, show that distribution of sole was not random when current velocities are high. The selected habitat is the one with low density tube worm aggregations. Overall, we conclude that structuring benthos plays an important role for juvenile flatfish, both as refuge and as feeding ground
Harbour porpoises Phocoena phocoena in the Eastern Scheldt: A resident Stock or trapped by a storm surge barrier?
Jansen, O.E. ; Aarts, G.M. ; Reijnders, P.J.H. - \ 2013
PLoS ONE 8 (2013)3. - ISSN 1932-6203
sea-level rise - stable-isotope analysis - food-web - feeding ecology - carbon isotopes - marine mammals - north-sea - nitrogen - diet - delta-c-13
Coastal protection measures are planned and executed worldwide to combat the effects of global warming and climate change, in particular the acceleration of sea level rise, higher storm surge flooding and extensive coastal inundation. The extent to which these defensive measures may impact coastal and estuarine ecosystems is still poorly understood. Since the building of a storm surge barrier, movement of harbour porpoises Phocoena phocoena in and out of the Eastern Scheldt tidal bay (SW-Netherlands) may be limited. To measure residency, porpoises stranded along the Dutch North Sea coast between 2006 and 2008 were sampled for muscle (n = 102) and bone tissue (n = 118), of which 9 muscle (8.8%) and 12 bone samples (10.2%) were collected from animals stranded within the Eastern Scheldt. Stable carbon (d13C) was analysed to get insight into the habitat use and residency of porpoises in the Eastern Scheldt. Our data showed significantly higher d13C values in the muscle of porpoises stranded within the Eastern Scheldt (µ = -17.7‰, SD = 0.4‰) compared to animals stranded along the Dutch coast (µ = -18.3‰, SD = 0.5‰). This suggests that most porpoises stranded in the Eastern Scheldt foraged there for a longer period. The distinct d13C signature of animals from the Eastern Scheldt was not observed in bone tissue, suggesting a relatively recent shift in habitat use rather than life-long residency of porpoises within the Eastern Scheldt. The high number of strandings within the Eastern Scheldt suggests a higher mortality rate compared to the Dutch coastal zone. Our study indicates that along with other changes in the physical environment, the storm surge barrier may play an important role in determining the residency of porpoises in the Eastern Scheldt, and that the area might act as an ecological trap for porpoises entering it.
Fishing for food : feeding ecology of harbour porpoises Phocoena phocoena and white-beaked dolphins Lagenorhynchus albirostris in Dutch waters
Jansen, O.E. - \ 2013
Wageningen University. Promotor(en): Peter Reijnders, co-promotor(en): Marten Scheffer. - S.l. : s.n. - ISBN 9789461734228 - 173
phocoena - lagenorhynchus - dolfijnen - voedingsecologie - diëten - kustwateren - noordzee - oosterschelde - nederland - phocoena - lagenorhynchus - dolphins - feeding ecology - diets - coastal water - north sea - eastern scheldt - netherlands
Harbour porpoises and white-beaked dolphins are the most common small cetaceans in the North Sea and Dutch coastal waters. The distribution and relative abundance of harbour porpoises and white-beaked dolphins from the Dutch coastal waters has changed significantly over the past decades. This thesis describes the past and present feeding ecology of these two species in Dutch coastal waters and investigates whether changes in abundance and relative distribution of porpoises reflect changes in their foodbase. For porpoises, three techniques for dietary analyses were combined, including stomach contents-, stable isotope- and fatty acid analysis, providing the most detailed description of their diet in time and space, elucidating differences between their short- and longer term diet.
Stable isotope analysis (δ13C and δ15N) were carried out in bone and muscle samples collected from porpoises stranded along the Dutch coast. Muscle δ15N values revealed that neonatal enrichment occurred and that larger porpoises, in particular males, seem to feed on lower trophic level species, compared to smaller individuals. Also bone δ15N values show that larger animals had fed on lower trophic levels in distant times. Seasonal variation in bone δ15N and δ13C values revealed two distinct groups of porpoises along the Dutch coast, a winter group (mainly males) that migrated from neighbouring regions and a Dutch subpopulation in summer (Chapter 2).
To assess the contribution of prey species to the porpoises’ diet, stable isotope analysis in both porpoise muscle and prey were carried out. With the use of a mixing model (Stable Isotope Analysis in R, SIAR), we revealed that 70-83% of the diet of porpoises consisted mainly of poor cod, mackerel, greater sandeel lesser sandeel, sprat and gobies. This highlights a higher importance of pelagic, schooling species in the porpoises’ diet compared to stomach contents, where 90.5% of the diet consisted of gobies, whiting, lesser sandeel, herring, cod and sprat. Porpoises thus also feed offshore on pelagic, schooling species, while they feed closer to shore on more benthic and demersal species shortly before they strand. This could be due to the distribution of prey species as well as differences in behaviour of porpoises and their prey between the coastal zone and offshore waters (Chapter 3).
The use of Quantitative Fatty Acid Analysis (QFASA) showed that the diet of porpoises consisted mainly of gobies, mackerel, smelt, herring and dragonet, pointing towards profound differences between the diet as estimated by QFASA and as deduced from stomach contents. This study revealed that the longer term diet of porpoises in Dutch coastal waters consists both of coastal species (e.g. gobies, smelt and dragonet) and also pelagic, schooling species (e.g. mackerel and herring). The results also brought to dawn possible methodological problems in using QFASA for porpoise diet estimation, emphasizing the importance of applying different dietary analysis techniques when studying marine mammal diets and the need for controlled feeding experiments in order to improve the interpretation of dietary analysis results (Chapter 5).
Besides new insights in the feeding ecology of porpoises, stable isotope analysis also elicited a non-food related conservation ecology issue. Distinct δ13C values in muscle of porpoises stranded in the Eastern Scheldt revealed that these porpoises foraged there for a longer period. This distinct δ13C signature of animals from the Eastern Scheldt was not observed in bone tissue, which suggests a relatively recent shift in habitat use rather than life-long residency of porpoises within the Eastern Scheldt. The high number of strandings within the Eastern Scheldt revealed a higher mortality rate compared to the Dutch coastal zone, indicating that along with other changes in the physical environment, the building of the storm surge barrier may play an important role in determining the residency of porpoises in the Eastern Scheldt, and that the area might act as an ecological trap for porpoises entering it. This is an example of the impact on marine species due to protection structures that emerge and respectively increase worldwide in response to the effects of global warming and climate change. It highlights that even semi-open structures, which are meant to ameliorate habitat loss, degradation and fragmentation, may still affect the abundance and distribution of migratory marine mammal species (Chapter 4).
The analysis of stomach contents of white-beaked dolphins showed that their diet was dominated by Gadidae. All other prey species combined contributed little to the diet by weight. The two most important prey species based in weight were whiting and cod. In numbers, gobies were most common, but these contributed little to the diet by weight. The overall diet showed a lasting predominance of whiting and cod, without clear changes over time (35 years) or differences between sexes or size-classes of dolphins and revealed that white-beaked dolphins in the south-eastern North Sea are specialist feeders, with a strong preference for whiting and cod (Chapter 6).
Stomach contents of juvenile white-beaked dolphins in our study revealed that at the age of about 1.5 years old, they had started feeding on solid food by taking a variety of small fish and invertebrate prey, mostly shrimp and squid. Immatures in our study, estimated to be 2-4 years old, still take small prey, including small gadoids, but also take larger gadoids. Calves apparently gradually learn to eat big fish by taking prey that is much smaller than those normally taken by their mothers. This study illustrates novel techniques for diet estimation to reconstruct sizes of shrimp and whiting from tail flaps and eye lenses, respectively (Chapter 7).
Most dietary studies on porpoises and white-beaked dolphins are deduced from stomach contents. This thesis has demonstrated that using indirect methods for studying the feeding ecology of marine mammals is a valuable addition to the more direct approach using stomach contents. It supports the need for multi-method approaches because by using only one technique, key prey species in the predator-prey relation may be missed or underestimated. Future ecological and fishery impact assessment studies and management decisions for the conservation of porpoises and white-beaked dolphins should acknowledge a difference between their long- and short-term diet. Large improvement in the interpretation of the results from diet analyses can be established either by controlled feeding experiments with animals in captivity or by studies that help to understand the common principals in dietary analyses (e.g. digestion rates, turnover rates of tissues, tissue-dependent isotopic fractionation between predator and prey and lipid metabolism within the animal) and variation of these between species.
Estimation of the dietary nutrient profile of free-roaming feral cats: possible implications for nutrition of domestic cats
Plantinga, E.A. ; Bosch, G. ; Hendriks, W.H. - \ 2011
The British journal of nutrition 106 (2011)S1. - ISSN 0007-1145 - p. S35 - S48.
fatty-acid-composition - wildcat felis-silvestris - trap-neuter-return - food-habits - house cats - feeding ecology - canary-islands - gastrointestinal-tract - new-zealand - carbohydrate-metabolism
Cats are strict carnivores and in the wild rely on a diet solely based on animal tissues to meet their specific and unique nutritional requirements. Although the feeding ecology of cats in the wild has been well documented in the literature, there is no information on the precise nutrient profile to which the cat's metabolism has adapted. The present study aimed to derive the dietary nutrient profile of free-living cats. Studies reporting the feeding habits of cats in the wild were reviewed and data on the nutrient composition of the consumed prey items obtained from the literature. Fifty-five studies reported feeding strategy data of cats in the wild. After specific exclusion criteria, twenty-seven studies were used to derive thirty individual dietary nutrient profiles. The results show that feral cats are obligatory carnivores, with their daily energy intake from crude protein being 52 %, from crude fat 46 % and from N-free extract only 2 %. Minerals and trace elements are consumed in relatively high concentrations compared with recommended allowances determined using empirical methods. The calculated nutrient profile may be considered the nutrient intake to which the cat's metabolic system has adapted. The present study provides insight into the nutritive, as well as possible non-nutritive aspects of a natural diet of whole prey for cats and provides novel ways to further improve feline diets to increase health and longevity.
The role of the invasive bivalve Ensis directus as food source for fish and birds in the Dutch coastal zone.
Tulp, I.Y.M. ; Craeymeersch, J.A.M. ; Leopold, M.F. ; Damme, C.J.G. van; Fey-Hofstede, F.E. ; Verdaat, J.P. - \ 2010
Estuarine Coastal and Shelf Science 90 (2010)3. - ISSN 0272-7714 - p. 116 - 128.
scoter melanitta-nigra - plaice pleuronectes-platessa - eiders somateria-mollissima - southern north-sea - limanda-limanda l - feeding ecology - wadden sea - population-structure - vipera cuvier - lesser weever
The razor clam Ensis directus was introduced to Europe presumably as larvae in ballast water around 1978. Starting in the German Bight it spread northward and southward along the continental coastline. Currently it is the most common shellfish species in the Dutch coastal zone, where it mainly occurs in the Voordelta and off the Wadden Sea islands. The mean density of E. directus in the Dutch coastal zone increased from around 2–5 individuals m-2 in the late ‘90’s to around 12–19 individuals m-2 from 2002 onwards. Diet studies show that E. directus makes up a significant proportion in the current diet of plaice, sole, dab, flounder and dragonet and in the diet of eider and common scoter. In recent years E. directus contributed 20–100% of the total wet weight in fish stomachs. The proportion E. directus in the diet increases with fish length. Based on stomach contents of oiled and beached birds and of faeces samples the recent frequency of occurrence is 85–90% in eider and 26% in common scoter. Also waders, gulls and corvids prey on E. directus but the contribution to the diet is still unquantified. Because of its great burying depth the species is not easily accessible. Fish either profit from massive die-offs that regularly occur, or they extract (probably only the smaller) individuals from the sediment. Sea ducks can extract E. directus from the sediment, while shorebirds and gulls feed on dying E. directus washing up on the shore. E. directus is possibly an important food item for fish and seabirds when they occur in high densities and in the right size classes. Since the availability depends greatly on massive die-offs, shell size, burying depth and water depth, it is probably not a very reliable food source. Judging from the role E. directus currently plays for the higher trophic levels, its introduction must have caused a major change in the food relations in its distribution area.
Het dieet van de Steenloper Arenaria interpres: een literatuuroverzicht
Cremer, J.S.M. ; Smit, C.J. - \ 2009
Texel : IMARES (Rapport / IMARES Wageningen UR C141/09) - 28
arenaria (vogels) - scolopacidae - voedering - diëten - voedingsgedrag - nederland - voedingsecologie - waddenzee - westerschelde - arenaria (birds) - scolopacidae - feeding - diets - feeding behaviour - netherlands - feeding ecology - wadden sea - western scheldt
Nutritional and health status of woolly monkeys
Ange-van Heugten, K.D. ; Timmer, S. ; Jansen, W.L. ; Verstegen, M.W.A. - \ 2008
International Journal of Primatology 29 (2008)1. - ISSN 0164-0291 - p. 183 - 194.
lagothrix-lagotricha-poeppigii - tinigua-national-park - reproductive parameters - feeding ecology - colombia - patterns - forest - diet - wild - toxoplasmosis
Woolly monkeys (Lagothrix lagotricha and L. flavicauda) are threatened species in the wild and in captivity. Numerous zoological institutions have historically kept Lagothrix lagotricha spp., but only a few of them have succeeded in breeding populations. Therefore the majority of institutions that formerly kept Lagothrix lagotricha are no longer able or willing to do so. Captive populations of the species have frequent health problems, most significantly hypertension and related disorders. Researchers have conducted free-ranging dietary and behavior studies with respect to woolly monkeys, but have established no concrete link between diet or nutrients and captive health problems. The available literature we discuss indicates that researchers need to examine the link further. In addition, it is critical to the survival of the primates to be able to keep breeding populations in captivity owing to increasing natural pressures such as deforestation and hunting. Therefore, better understanding of the captive and free-ranging behavior and health parameters of the species is vital to ensure their survival and to maintain forest health and diversity. Researchers need to conduct large-scale research studies comparing the health and complete diet of individuals in the wild and captivity to resolve health problems facing the species in captivity.
Distribution, abundance and ecological relevance of pelagic fishes in the Lazarev Sea, Southern Ocean
Florentino De Souza Silva, A.P. ; Putte, A.P. van de; Siegel, V. ; Pakhomov, E.A. ; Franeker, J.A. van; Meesters, H.W.G. ; Colckaert, F.A.M. - \ 2008
Marine Ecology Progress Series 367 (2008). - ISSN 0171-8630 - p. 271 - 282.
antarctic mesopelagic fishes - marine food-web - nw weddell sea - euphausia-superba - shetland islands - proximate composition - community structure - foraging behavior - feeding ecology - open waters
The distribution and abundance of larval and postlarval fishes was investigated in the Lazarev Sea, Southern Ocean, in March and April 2004. The upper 200 m of the water column were sampled with an 8 m2 rectangular midwater trawl at 93 stations. The larval species community clustered in a diverse coastal community with high densities of Antarctic silverfish Pleuragramma antarcticum larvae and a less diverse offshore community dominated by Antarctic jonasfish Notolepis coatsi and the lanternfish Electrona antarctica. No postlarval fish were caught in coastal areas. The offshore community of postlarval fishes consisted of the deep-sea smelt Bathylagus antarcticus, and the lanternfishes Gymnoscopelus braueri, G. nicholsi and E. antarctica. The latter species clearly dominated, occurring at mean individual and wet mass densities of 0.17 individuals m¿2 and 0.26 g m¿2, respectively. A generalized additive model significantly related the density of postlarval E. antarctica to the abundance of Antarctic krill Euphausia superba, ocean depth and sea surface temperature. The diet of E. antarctica was dominated by copepods and euphausiid larvae. Mean energy density of E. antarctica in the upper 200 m was 2.8 kJ m¿2, which is equivalent to 36% of the energy stored in Antarctic krill stocks and probably would be considerably higher if a greater depth range were considered. This suggests that E. antarctica is a major energy transmitter in the food web of the Lazarev Sea, challenging the classical krill-dominated food web paradigm of the Southern Ocean
The Ecology of Browsing and Grazing
Gordon, I.J. ; Prins, H.H.T. - \ 2008
Berlin, Heidelberg : Springer (Ecological Studies 195) - ISBN 9783540724216 - 328
afgrazen - voedingsgewoonten - begrazing - herbivoren - dierecologie - plantenecologie - voedingsgedrag - populatiedynamica - biodiversiteit - vegetatie - grote grazers - voedingsecologie - browsing - feeding habits - grazing - herbivores - animal ecology - plant ecology - feeding behaviour - population dynamics - biodiversity - vegetation - large herbivores - feeding ecology
De voedselsituatie voor gruttokuikens bij agrarisch mozaïekbeheer
Kleijn, D. ; Dimmers, W.J. ; Kats, R.J.M. van; Melman, T.C.P. ; Schekkerman, H. - \ 2007
Wageningen : Alterra (Alterra-rapport 1487) - 50
limosa limosa - voedering - natuurbescherming - agrarische bedrijfsvoering - graslandbeheer - overleving - ruimtelijke variatie - nederland - voedingsecologie - weidevogels - agrarisch natuurbeheer - limosa limosa - feeding - nature conservation - farm management - grassland management - survival - spatial variation - netherlands - feeding ecology - grassland birds - agri-environment schemes
Mozaiekbeheer blijkt niet te leiden tot de gewenste verhoging van overleving bij grutto's. In dit rapport is onderzocht wat de vegetatiesamenstelling van de graslanden is en wat het aanbod aan ongewervelden voor weidevogels in die percelen is. Het blijkt dat kruidenrijke, schrale percelen een goede vegetatiestructuur gedurende de gehele kuikenperiode hebben; terwijl de ongewervelden in mei hoger is dan in juni
Energy content of Antarctic mesopelagic fishes: implications for the marine food web
Putte, A. van de; Florentino De Souza Silva, A.P. ; Franeker, J.A. van - \ 2006
Polar Biology 29 (2006)12. - ISSN 0722-4060 - p. 1045 - 1051.
south shetland islands - king-george-island - proximate composition - fatty-acid - fur seals - arctocephalus-gazella - electrona-antarctica - community structure - feeding ecology - open waters
For a better understanding of the role of mesopelagic fish in the Southern Ocean food web, the energy and water content of Bathylagus antarcticus, Electrona antarctica and Gymnoscopelus braueri from the Lazarev Sea were investigated. Mean dry weight energy content of B. antarcticus (20.4 kJ g(-1)) was significantly lower than in E. antarctica and G. braueri (both 29.4 kJ g(-1)). In E. antarctica, an increase of dry weight energy density with age was evident from 26.9 kJ g(-1) in juveniles of less than 1 year of age to 32.0 kJ g(-1) in 3-year-old fish. Water content decreased with size in all three species. Abundant high-energy species such as E. antarctica are at a key position in the food web. Due to a marked influence of age on energy content, population structure can be an important variable in estimates of energy fluxes in the Southern Ocean ecosystem.