Comparative Feeding Ecology of Two Sympatric Greenling Species, <Emphasis Type="Italic">Hexagrammos otakii</Emphasis> and <Emphasis Type="Italic">Hexagrammos agrammus</Emphasis> in Eelgrass <Emphasis Type="Italic">Zostera marina</Emphasis> Beds

Synopsis Feeding ecology was compared between sympatric greenling species, Hexagrammos otakii and H. agrammus in the eelgrass beds in Jindong Bay, Korea, from January to December. These two species had similar diets composed of crustaceans, polychaetes, gastropods and fishes; both species consumed primarily crustaceans throughout study periods. H. otakii, however, fed a greater proportion of polychaetes and fishes than H. agrammus. H. agrammus had a greater proportion of gastropods in their diets. The diet of both species underwent size-related changes; smaller individuals of H. otakii and H. agrammus consumed amphipods (gammarid amphipods and caprellid amphipods), while larger individuals of H. otakii ate polychaetes and fishes and those of H. agrammus fed mainly on gastropods and crabs. The diet of H. otakii underwent seasonal changes; H. otakii consumed mainly polychaetes and fishes during January and February 2002 but amphipods during March and May 2002. H. agrammus, however, ate mainly gastropods and crabs all seasons. H. otakii underwent also a significant diel changes that could be related to difference of prey availability. Thus the nocturnal emergence of gammarid amphipods, polychaetes and fishes explained their greater consumption by H. otakii. Dietary breadth of both species was lower in the smallest individuals (<5 cm SL) and in March and April 2002. This was due to the disproportionate dry mass attributable to the consumption of amphipods by both H. otakii and H. agrammus. Dietary overlap of both species was relatively moderate to high, in particular in <9.9 cm SL (0.62 – 0.71) from May to July 2002 (0.63 – 0.71). This is coincident with higher abundances of crabs, caridean shrimps and polychaetes in the study area, and it was assumed that these prey species were not limited resources. Higher dietary overlap was correlated with an abundance of a shared resource and did not indicate the interspecific competition between H. otakii and H. agrammus.     

Dietary composition of the blue swimmer crab Portunus pelagicus L. Does it vary with body size and shell state and between estuaries?

The aim of this study was to determine the diets of Portunus pelagicus in the large Peel-Harvey and Leschenault estuaries in south-western Australia in order to ascertain whether the dietary composition of this crab changes with body size during two different moult stages and differs between the two estuaries. Portunus pelagicus, ranging in age and carapace width from ca. 2 months and 12 mm to ca. 112 years and 159 mm, were collected from the shallow basins of the Peel-Harvey and Leschenault estuaries. Examination of the cardiac stomachs of these crabs showed that P. pelagicus does not feed just before or immediately after moulting and that the stomachs of recently-moulted crabs contained significantly more food than those of intermoult crabs. Although the volumetric contribution made by calcareous material to the stomach contents was similarly high in all size classes of recently-moulted crabs, i.e. 47 to 55%, the volumetric contributions made by small bivalves decreased with body size, whereas the reverse occurred with shell fragments of large decapods and, to a lesser extent, polychaetes. The dietary compositions of intermoult crabs were shown by classification and multi-dimensional scaling ordination to differ markedly from those of recently-moulted crabs and to undergo similar progressive ontogenetic changes in both the Peel-Harvey and Leschenault estuaries. Thus, the contribution made by small benthic and epibenthic crustaceans, such as amphipods and tanaids, declined with increasing body size, whereas the reverse occurred with larger prey, such as nereid polychaetes, small decapods and teleosts. The dietary composition of P. pelagicus was influenced more by moult stage, i.e. recently moulted vs. intermoult, than by body size. Although the dietary compositions of P. pelagicus in the two estuaries were not significantly different, they did differ from those recorded from coastal marine waters in the same region, thereby reflecting differences in the potential prey in those two environments.     

The diets of two co-occurring marine teleosts, Parequula melbournensis and Pseudocaranx wrighti, and their relationships to body size and mouth morphology, and the season and location of capture

The dietary compositions of the co-occurring gerreid Parequula melbournensis and the carangid Pseudocaranx wrighti have been determined, using samples collected seasonally from a 200 km stretch of coastal water in temperate Australia, in which these species are very abundant. Although the small representatives of P. melbournensis and P. wrighti both fed to a large extent on copepods, the latter ingested a wider variety of prey and thus had a greater dietary breadth. The diets of both species changed markedly as body size increased. The larger representatives of P. melbournensis fed mainly on onuphid and other polychaetes, whereas those of P. wrighti consumed a considerable volume of crustaceans, molluscs, polychaetes other than onuphids, and echinoderms. The above differences account for the dietary breadth being far greater in large P. wrighti than large P. melbournensis. Schoener's index and classification showed that dietary overlap between P. melbournensis and P. wrighti was low, suggesting that food resources were partitioned between these two demersal species. Intraspecific overlap was less amongst the length classes of small fish than among those of larger fish, indicating that any competition for food would be less among small fish, when growth would have been most rapid. The larger P. melbournensis fed mainly on prey types which were relatively sessile and can protrude from the substrate, such as tube-dwelling onuphid polychaetes, whereas the larger P. wrighti fed on a variety of epibenthic and/or more mobile species, such as mysids, amphipods, bivalves, gastropods, nereid polychaetes and echinoderms. Although P. melbournensis foraged to a far greater extent on a sessile fauna that occurs on or in the substrate, it ingested a far smaller amount of sand than P. wrighti, even though this latter species fed on a more epibenthic fauna. The presence of smaller amounts of sand in the stomach contents of P. melbournensis than of P. wrighti, presumably reflects the possession of a smaller and far more protrusible mouth, which enabled its sessile prey to be targetted more precisely. The dietary composition of P. melbournensis and P. wrighti underwent some seasonal changes, presumably reflecting seasonal fluctuations in the densities of prey species, and that of P. melbournensis differed slightly between some sites.     

Chemical defense in the egg masses of benthic invertebrates: an assessment of antibacterial activity in 39 mollusks and 4 polychaetes.

Many marine invertebrates deposit benthic egg masses that are potentially vulnerable to microbial infection. To help counter this threat these species may have evolved some form of chemical protection for their encapsulated embryos. In this study the egg masses from 7 marine mollusks were tested for antibacterial activity against 4 marine pathogens: Enterococcus sericolicida, Vibrio anguillarum, Vibrio alginolyticus, and Vibrio harveyi. Extracts from all of these egg masses were found to inhibit the growth of at least 1 marine bacterium at concentrations that approximate the natural concentration of extract in the egg masses. The egg masses of 39 mollusks and 4 polychaetes were then tested for antibacterial activity against 3 human pathogenic bacteria; Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Activity was detected in the egg masses from 34 species, including 2 polychaetes and mollusks from two classes and 18 families. Antibacterial activity in molluskan egg masses was found to extend across the marine, estuarine, freshwater, and terrestrial environments. Both gelatinous egg masses and tough egg capsules were found to inhibit microbial growth, suggesting that physical protection alone may not be sufficient to protect the eggs. Antimicrobial activity was observed in the fresh egg masses but not in the well-developed egg masses of a subset of species. The results of this study indicate that a wide range of invertebrates use chemical defense to protect their early stage embryos against bacterial infection.     

Food partitioning and spatial subsidy in shelter‐limited fishes inhabiting patchy reefs of Patagonia

The diets of the most conspicuous reef‐fish species from northern Patagonia, the carnivorous species Pseudopercis semifasciata, Acanthistius patachonicus, Pinguipes brasilianus and Sebastes oculatus were studied. Pinguipes brasilianus had the narrowest diet and most specialized feeding strategy, preying mostly on reef‐dwelling organisms such as sea urchins, limpets, bivalves, crabs and polychaetes. The diet of A. patachonicus was characterized by the presence of reef and soft‐bottom benthic organisms, mainly polychaetes, crabs and fishes. Pseudopercis semifasciata showed the broadest spectrum of prey items, preying upon reef, soft‐bottom and transient organism (mainly fishes, cephalopods and crabs). All S. oculatus guts were empty, but stable‐isotope analyses suggested that this species consumed small fishes and crabs. In general, P. brasilianus depended on local prey populations and ate different reef‐dwelling prey than the other species. Pseudopercis semifasciata, A. patachonicus and probably S. oculatus, however, had overlapping trophic niches and consumed resources from adjacent environments. The latter probably reduces the importance of food as a limiting resource for these reef‐fish populations, facilitating their coexistence in spite of their high trophic overlap.     

Life-history styles of fishes in South African estuaries

Synopsis Fish utilizing South African estuaries may be divided into two major groups according to the location of their spawning sites. The marine group comprises large species which spawn at sea, enter estuaries mainly as juveniles, and return to the sea prior to attaining sexual maturity. The estuarine group is dominated by small species which have the ability to complete their life cycle within the estuarine environment. They tend to produce relatively few, demersal eggs, or exhibit parental care, which facilitates the retention of eggs and young within the estuary, whereas the marine group release large numbers of small pelagic eggs during spawning and exhibit no parental care. This is contrary to the theory that estuaries (unpredictable environments) should favour altricial life-history styles and the marine inshore zone (a more predictable environment) should favour precocial styles. However, if the total ichthyofauna of South African estuaries is considered, then altricial species predominate. The fact that both altricial and precocial traits are well represented within the overall estuarine fish community suggests that the various taxa have adapted their life-history styles, in different ways, to ensure the utilization of abundant food resources available within these fluctuating systems. A detailed comparison of the life-history styles of the estuarine teleostGilchristella aestuaria and the marine fishMugil cephalus is used to illustrate the contrasting manner in which these two species have succeeded in exploiting South African estuaries.     

Dynamics and predictive modelling of Vibrio spp. in the Neuse River Estuary, North Carolina, USA

Vibrio spp. are naturally occurring bacteria in marine and estuarine environments around the world. The genus includes several human and animal pathogens that can negatively impact human health, seafood and aquaculture. Vibrio spp. populations are capable of rapid adaptation in response to changing environmental conditions, making them dynamic over short-term and seasonal scales. Temperature, vertical mixing, tidal flushing, climate, precipitation and nutrient loading can change the estuarine environment and subsequently alter microbial community structure, including Vibrio spp., affecting estuarine water quality and public health. To describe these dynamics, Vibrio spp. concentrations and a range of microbial, physical and chemical measures were monitored every 2 weeks and after storm events for 19 months in the Neuse River Estuary (NRE). Results showed clear seasonal and geographic trends in Vibrio spp. abundance. Multiple regression analysis revealed a strong relationship to temperature and salinity, with additional minor influences of chlorophyll a and dissolved organic carbon. Similar models based on easily measured environmental parameters should be pursued for individual Vibrio species in the NRE and other estuarine environments. Predictive models provide useful information for managers, researchers and modellers of estuarine ecosystems.     

Feeding ecology and trophic position of a Mediterranean endemic ray: consistency between sexes, maturity stages and seasons

The study of trophic ecology of marine predators is crucial to better understand the ecological factors that condition their role within marine ecosystems. Here we investigated the trophic habits and position of a Mediterranean endemic predator, the starry ray, Raja asterias. Specifically, we quantified the diet composition of this endemic ray in a highly exploited area of the NW Mediterranean, and we evaluated the effects of sex, maturity-stage and season on its feeding habits. Our results revealed that the starry ray is a predator of crustaceans (crabs and shrimps), and to a lower extent on teleosts, molluscs and polychaetes. This species has a high trophic position within its food web and feeds mainly on crabs (mainly Liocarcinus depurator and Goneplax rhomboides), independent of their sex, maturity-stage or season. The great importance of crabs in the diet of starry ray may be due to the fact that crabs are the dominant crustaceans in terms of biomass and abundance in the area where starry rays were collected, thus allowing them to exploit the most abundant food resource. Since the starry ray has shown a progressive decline on the catch, further research is needed to analyse the main drivers of starry ray dynamics in the Western Mediterranean Sea. Our results present important new data that will allow us to further explore the population dynamics of starry rays and the role of crustacean availability and fishing activity.     

Inter- and intraspecific variability in the chemical composition of the mineral phase of cements from several tube-building polychaetes

Several species of marine polychaetes reside in individual protective tubes. These tubes may be agglomerated in patches of varied sizes with very high densities, or form massive reef-like mounds which can be stretch over several kilometers. These polychaetes can thus be considered as the most important building organisms after corals in coastal environments. We especially focused on several species belonging to the families of Sabellariidae, Terrebeliidae and Pectinariidae. Tubes grains are glued together with biomineralized cement secreted from a building organ connected to specialized glands. Different methods of micro-analysis were used to analyze the biomineral components of these cements for four varyingly gregarious tube-building polychaetes: Lanice conchilega, Pectinaria koreni, Sabellaria alveolata and Phragmatopoma caudata. The aim of this study is to describe and compare the inter- and the intraspecific variability in the main biomineral components of cement at local, regional and continental scales. Scanning Electron Microscopy confirms an identical structure of the cement within species of Sabellariidae in Europe and America. Electron Probe Micro-Analysis (EPMA) confirms the presence of calcium, phosphorus, and magnesium plus traces of manganese in all cements, with varying concentrations of these elements at different locations for the same species or for different species at the same location. Finally, our dataset is compared with previous studies from literature.     

Early ontogeny of Galeichthys feliceps from the south east coast of South Africa

The early development of Galeichthys feliceps (Valenciennes, 1840) was investigated using a combination of incubator-reared embryos and embryos removed from the buccal cavities of wild-caught parents. The eggs were 15·7 mm in diameter and the average brood size was 49. Hatching occurred at an advanced developmental state after approximately 75–80 days, when branchial and fin differentiation were complete. Exogenous feeding began within the adult buccal cavity shortly after hatching. The young were released as juveniles after approximately 140 days, at a total length of 54 mm.     

Freshwater habitat use by a moray eel species,Gymnothorax polyuranodon,in Fiji shown by otolith microchemistry

Freshwater eels of the Anguillidae are diadromous because they migrate between ocean and freshwater environments, but other anguilliform fishes are generally considered to be strictly marine species. A few marine eels of the Muraenidae and Ophichthidae have occasionally been found in freshwater or estuaries, indicating that anguillids are not the only anguilliform eels that can use freshwater in some parts of the world. The moray eel Gymnothorax polyuranodon is one species that is known to be present in freshwater in the Indo-Pacific, but its life history is unknown. One way to evaluate what types of habitats are used by fishes is to determine the ratio of strontium (Sr) to calcium (Ca) in their otoliths, because this can show if they have used freshwater or saltwater environments. To evaluate the patterns of freshwater use by this unusual species of marine eel, the otolith Sr/Ca ratios of four G. polyuranodon (275–344 mm) caught in a freshwater stream of Fiji were analyzed. The consistently low Sr/Ca values (0–4) indicated upstream movement after settlement and freshwater or estuarine residence of all four individuals. These eels did not appear to have entered freshwater just for a short time period, which is consistent with other reports that this species is present in estuarine and freshwater habitats. This suggests that G. polyuranodon may be a catadromous species of marine eel. The similarities and differences between the life histories of anguillid eels and the few marine eels that have evolved the ability to invade freshwater habitats is discussed in relation to the evolutionary origin of diadromy in anguilliform fishes that originated in the marine environment.     

Feeding ecology of juvenile flatfishes of the surf zone of a sandy beach

Prey items of 0- and 1-group plaice Pleuronectes platessa , sole Solea solea , brill Scophthalmus rhombus , turbot S. maximus and dab Limanda limanda of the surf zone of a Belgian sandy beach, included hyperbenthic (e.g. mysids), endobenthic (e.g. polychaetes) and epibenthic (e.g. shrimps) species. Little dietary overlap was observed. If diet overlap did occur, it mainly involved prey species that are dominant in the surf zone of Belgian beaches, such as shrimps and mysids. These results suggest an opportunistic utilization by flatfish of the available food resources in surf zone ecosystems. Also, two strategically different feeding habits could be distinguished between the five flatfish species. Turbot and brill mainly fed on large, highly mobile prey (e.g. fish, mysids) and had a rather narrow prey spectrum, whereas plaice, dab and sole ate more benthic prey (e.g. polychaetes) and had a broader prey spectrum.     

FISH CONSERVATION IN SOUTH AFRICAN ESTUARIES: PRESSURES,PROBLEMS AND PROSPECTS

Summary

A review of the conservation status of fish in the estuarine environment around the South African coastline reveals that some species face serious problems associated either with habitat destruction, and its associated biological, physical and chemical components or exploitation. The 65 species considered fall into three categories; truly estuarine species, which are dependent on estuaries for their entire life; marine species dependent on estuaries during the juvenile phase of their life cycle; and marine species whose juveniles occur mainly in estuaries but are also found at sea. Included in the first two categories are 14 species of fish which are on the South African Red Data list. These comprise one species which is endangered, five which are vulnerable and eight which are rare. All groups are considered in relation to factors in estuaries which are affecting their populations. A conservation strategy is suggested for certain estuarine types or for specific estuaries which could ensure the survival of the entire range of estuarine faunas.     

Lack of transmission of Hematodinium sp. in the blue crab Callinectes sapidus through cannibalism

Hematodinium spp. are parasitic dinoflagellates of marine crustaceans. Outbreaks of Hematodinium sp. have impacted commercial landings of the blue crab Callinectes sapidus in the coastal bays of Virginia and Maryland (USA), with seasonal peaks in prevalence reaching 85%. The life cycle and transmission routes of the parasite in blue crabs are poorly understood. Cannibalism and waterborne transmission may be routes of transmission, although little conclusive evidence has been reported for these modes. We examined cannibalism as a route by a series of experiments wherein we repeatedly fed adult and juvenile crabs the tissues of crabs infected with Hematodinium. In each experiment, feeding was done 3 times over the course of 1 wk. Only 2 of 120 crabs were infected within 7 to 9 d after feeding, and these 2 were likely infected prior to the experimental exposures. Crabs inoculated with hemolymph from infected donors served as positive controls. They developed infections over 11 to 21 d, indicating that the Hematodinium sp. used in the cannibalism trials was infectious at the time of inoculation. Because amphipods also harbor Hematodinium-like infections, we fed tissues of infected crabs to the estuarine amphipod Leptocheirus plumulosus. Hematodinium DNA was detected in amphipods shortly after feeding, but not in animals held for longer periods, nor was it observed in histological preparations. Amphipods did not obtain infections by scavenging infected crab tissues. Our results show that Hematodinium sp. is not effectively transmitted through ingestion of diseased tissues, indicating that cannibalism may not be a major route of transmission for Hematodinium sp. in blue crabs.     

Biodiversity and functioning of polychaetes in benthic sediments

Polychaetes are well represented in most marine and estuarine environments, both in terms of number of individuals and species, and they typically contribute a significant percentage of the total macrofaunal diversity. They exhibit considerable variations in recruitment in both time and space, which is then often reflected in adult distributions. Whilst families and genera of polychaetes have wide distributions, normally species have discrete distributions. Polychaetes are often classified according to their diverse feeding guilds. They play a major role in the functioning of benthic communities, in terms of recycling and reworking of benthic sediments, bioturbating sediments and in the burial of organic matter. Some species form dense tubiculous colonies which can radically change recruitment patterns of other infaunal organisms. Polychaetes, by their burrowing and feeding activity, may considerably enhance various sedimentary processes. However, much remains to be learnt as to how benthic communities function, and how they may change in function as they are increasingly being impacted especially in coastal waters adjacent to centres of population.     

Characterisation of two novel CYP4 genes from the marine polychaete Nereis virens and their involvement in pyrene hydroxylase activity

Cytochrome P450 enzymes (CYP enzymes) catalyse the initial step in biotransformation of xenobiotics like polycyclic aromatic hydrocarbons (PAHs). The marine polychaete Nereis virens has a high capacity for biotransformation of PAHs. In the present study, the complete cDNA sequences of two novel CYP genes isolated from N. virens gut tissue are reported. One named CYP342A1, the first member of a new family and the other named CYP4BB1, the first member of a new subfamily. This is the first investigation of specific CYP enzymes from marine polychaetes in which catalytic activity has been determined. Both CYP enzymes had monooxygenase activity and catalysed hydroxylation of pyrene to 1-hydroxypyrene. Based on the present results it is likely that both CYP4BB1 and CYP342A1 are involved in xenobiotic biotransformation. Furthermore, site-directed mutagenesis of the conserved cysteine residue of the heme binding domain resulted in complete loss of monooxygenase activity of both CYP enzymes, indicating that this cysteine residue is indispensable for monooxygenase activity of invertebrate CYP enzymes, as has been well documented in vertebrates. Considering the important role of CYP enzymes in biotransformation of xenobiotics and the presence of N. virens in estuarine environments that accumulates organic xenobiotics, our results are important in understanding the molecular mechanism of biotransformation in marine polychaetes.     

污损性管栖多毛类生态特点及研究展望

污损性管栖多毛类属环节动物门,主要由龙介虫科(Serpulidae)、螺旋虫科(Spirorbidae)、缨鳃虫科(Sabellidae)和蛰龙介科(Terebllidae)4科55种组成,以华美盘管虫(Hydroides elegans)、内刺盘管虫(H.ezoensis)、龙介虫(Serpula vermicularis)和克氏无襟毛虫(Pomatoleios kraussii)等种类为优势种,通常成批的附着在物体表面,严重影响人工设施的安全和性能。污损性管栖多毛类的分布具有明显的地域性和季节性,并与深度有关。今后工作应进一步开展管栖多毛类基础生物学研究,探讨外来种的入侵及影响,丰富和发展生态和分类等方面的研究内容。     

A review of the influence of biogeography,riverine linkages,and marine connectivity on fish assemblages in evolving lagoons and lakes of coastal southern Africa

The Holocene evolution of eight South African coastal lakes and lagoons is examined and related to changes in fish composition over that period. Historical and current connectivity with riverine and marine environments are the primary determinants of present‐day fish assemblages in these systems. A small and remarkably consistent group of relict estuarine species have persisted in these coastal lakes and lagoons. The loss or reduction of connectivity with the sea has impacted on the diversity of marine fishes in all eight study systems, with no marine fishes occurring in those water bodies where connectivity has been completely broken (e.g. Sibaya, Groenvlei). In systems that have retained tenuous linkages with the sea (e.g., Verlorenvlei, Wilderness lakes), elements of the marine fish assemblage have persisted, especially the presence of facultative catadromous species. Freshwater fish diversity in coastal lakes and lagoons is a function of historical and present biogeography and salinity. From a freshwater biogeography perspective, the inflowing rivers of the four temperate systems reviewed here contain three or fewer native freshwater fishes, while the subtropical lakes that are fed by river systems contain up to 40 freshwater fish species. Thus, the significantly higher fish species diversity in subtropical versus temperate coastal lakes and lagoons comes as no surprise. Fish species diversity has been increased further in some systems (e.g., Groenvlei) by alien fish introductions. However, the impacts of fish introductions and translocations have not been studied in the coastal lakes and lagoons of South Africa. In these closed systems, it is probable that predation impacts on small estuarine fishes are significant. The recent alien fish introductions is an example of the growing threats to these systems during the Anthropocene, a period when human activities have had significant negative impacts and show potential to match the changes recorded during the entire Holocene.     

Development of an 18S rRNA gene-targeted PCR-based diagnostic for the blue crab parasite Hematodinium sp.

The 18S rRNA gene from Hematodinum sp., a parasitic dinoflagellate that infects blue crabs, was amplified, cloned, and sequenced. The sequence showed a high similarity (95% at the nucleotide level) to sequences obtained from other dinoflagellate species, including both free-living and symbiotic species. Sequence similarity was much lower when compared with parasites of other marine invertebrates with similar life histories and with the 18S rRNA gene from the blue crab. Based on comparison of sequence alignments between Hematodinium, other dinoflagellate species, protozoan pathogens of oysters, and blue crab 18S rRNA gene sequences, 2 sets of PCR primers that specifically amplified fragments of the Hematodinium 18S rRNA gene were developed and tested. One of these primer sets (Hemat-F-1487 and Hemat-R-1654) amplified a 187 bp fragment that could be used routinely as a diagnostic test for the presence of Hematodinium in hemolymph from blue crabs. This fragment was consistently amplified from genomic DNA extracted from hemolymph of Hematodinium infected blue crabs. Comparison between the PCR technique and standard histological examination indicated that the PCR technique was reliable and provided 1000 times more sensitivity than the histological methods. The sensitivity of the PCR diagnostic was estimated to be one parasite cell among 300,000 crab hemocytes. Preliminary studies using the PCR diagnostic technique suggest that Hematodinium sp. is absent in crabs collected from waters with low salinity (5 to 10 ppt), but common in crabs from higher salinity environments in estuarine waters from southeastern Georgia (USA).     

Spatial and temporal variation in the diet of the sandy beach gastropod Olivella minuta

Marine gastropods exert a strong influence on the structure of marine ecosystems through their foraging activities, yet little is known about how environmental differences in space and time may affect their feeding behavior. To enhance the knowledge about the trophic ecology of coastal benthic species, we investigated temporal and spatial variations in the diet of the sandy beach gastropod Olivella minuta. We collected individuals of O. minuta seasonally, over 1 year, at two sandy beaches with different morphodynamic characteristics (Araçá Bay, an ultra‐dissipative tidal flat, and Barequeçaba Beach, a dissipative beach) and analyzed the stomach contents of specimens of O. minuta. We identified approximately 15,000 food items, which we grouped into 14 categories. Thirteen food categories were found at each area, but significant differences in diet were observed between sites and sampling periods. Individuals from Araçá consumed an overall larger quantity and diversity of food items, which consisted mainly of foraminiferans, polychaetes, and crustaceans. At Barequeçaba, diatoms were the most important item, followed by crustaceans and polychaetes. Temporal variation depended on sites: the number of food items in the stomachs of individuals of O. minuta and dietary composition was roughly constant over time at Araçá, whereas larger variations were observed at Barequeçaba. Although O. minuta has been previously characterized as a carnivore/scavenger, our results show that the diet of this species varies in space and time and comprises a large variety of food resources. The species thus plays a role in the cycling of both vegetal and animal organic matter. This generalist behavior may allow individuals to shift their diet according to habitat alterations and food availability, thereby enhancing the persistence and resilience of O. minuta in different environments or future climate change scenarios.