Lolliguncula Brevis Research Articles

Life History Patterns of the Atlantic Brief Squid, Lolliguncula brevis (Blainville, 1823), in the Charleston Harbor Estuary, South Carolina, USA

The Atlantic brief squid, Lolliguncula brevis, is a euryhaline cephalopod that inhabits shallow, continental shelf habitats from Argentina to the Bay of Fundy. In the southeastern United States, brief squid can account for a considerable portion of the estuarine animal biomass and are an important component of the diets of species with high priority for management and conservation. Historical data from South Carolina Department of Natural Resources suggest that brief squid exhibit spatially and temporally variable size-frequency distributions within the Charleston Harbor estuary. Prior to this study, however, detailed life history information for this species was lacking in the region. Samples of brief squid were collected monthly at four stations along a salinity gradient within the Charleston Harbor estuary in 2019 to investigate temporal and spatial patterns of abundance, sex, size, and maturity. Season and station were significantly related to brief squid abundance, which was greater for all sexes in spring, summer, and fall than in winter. Catches of brief squid were dominated by immature squid compared with mature squid. Excluding sexually indistinct squid, and across all seasons, significantly more males were collected than females. Mean brief squid size tended to be larger in May than in several other months of the year, largely due to the lower abundance of small squid in that month. Logistic regression analyses indicated that brief squid size-at-maturity occurred at 50.2 mm for males and 59.2 mm for females. The presence of both small and large brief squid throughout the year at all stations supports a pattern of overlapping cohorts, whereas the continual presence of immature brief squid at all stations suggests asynchronous recruitment. This study provides valuable life history information that can be used to support the conservation and management of organisms that are either prey or predators of brief squid within the Charleston Harbor estuary. Further research over multiple years and within other estuaries in the Georgia Bight is needed, however, to determine how the life history patterns observed in this study apply more broadly across the region.

Vectored jets power arms-first and tail-first turns differently in brief squid with assistance from fins and keeled arms.

Squids maneuver to capture prey, elude predators, navigate complex habitats and deny rivals access to mates. Despite the ecological importance of this essential locomotive function, limited quantitative data on turning performance and wake dynamics of squids are available. To better understand the contribution of the jet, fins and arms to turns, the role of orientation (i.e. arms first versus tail first) in maneuvering, and the relationship between jet flow and turning performance, kinematic and 3D velocimetry data were collected in tandem from brief squid, Lolliguncula brevis. The pulsed jet, which can be vectored to direct flows, was the primary driver of most turning behaviors, producing flows with the highest impulse magnitude and angular impulse about the main axis of the turn (yaw) and secondary axes (roll and pitch). The fins and keeled arms played subordinate but important roles in turning performance, contributing to angular impulse, stabilizing the maneuver along multiple axes and/or reducing rotational resistance. Orientation affected turning performance and dynamics, with tail-first turns being associated with greater impulse and angular impulse, longer jet structures, higher jet velocities and greater angular turning velocities than arms-first turns. Conversely, arms-first turns involved shorter, slower jets with less impulse, but these directed short pulses resulted in lower minimum length-specific turning radii. Although the length-to-diameter ratio (L/D) of ejected jet flow was a useful metric for characterizing vortical flow features, it, by itself, was not a reliable predictor of angular velocity or turning radii, which reflects the complexity of the squid multi-propulsor system.

Draft Genome Sequence of a Harveyi Clade Bacterium Isolated from Lolliguncula brevis Squid.

Vibrio species of the Harveyi clade are commonly found in free-living and host-associated marine habitats. Here, we report the draft genome sequence for a Harveyi clade bacterium, Vibrio sp. strain LB10LO1, which was isolated from the Atlantic brief squid Lolliguncula brevis.

Decadal-Scale Changes in Subtidal Nekton Assemblages in a Warm-Temperate Estuary

Coincidental long-term changes in estuarine nekton assemblages and environmental conditions are widely reported. In this study, from a warm-temperate, high salinity, salt marsh-dominated estuary in the southeastern USA, decreases in overall abundance, shifts in species and life stage composition, and changes in seasonal patterns of occurrence coincided with increased water temperature. Biweekly trawl collections in a subtidal creek were made during two 4-year periods separated by more than 30 years. Of the total 111 taxa in the North Inlet estuary, South Carolina, 64% (71) occurred during both the historic (1981–84) and recent (2013–16) periods. The top five species and their proportions of the total annual catches changed between periods. In the recent study period, near-bottom species (Lagodon rhomboides, Bairdiella chrysoura, Litopenaeus setiferus) increased, and pelagic species (Anchoa spp. and Lolliguncula brevis) decreased. The mean abundance of total nekton in the recent period was approximately 50% of historic abundance. Large, but temporary increases in nekton abundance occurred when salinity decreased after major storms. In the recent study period, shifts in the timing of peak abundances from spring to fall, the occurrence of juveniles during winter, and increased diversity suggested responses to significantly warmer winters and summers. Over the 30 year period, the subtidal nekton assemblage transitioned to a state of lower abundance and different composition. Future increases in water temperature, incidences of major storms, and modifications of estuarine habitats due to rising sea level could lead to additional changes in the fauna of warm-temperate estuaries.

Draft genome sequence of a harveyi clade bacterium isolated from lolliguncula brevis squid

Draft genome sequence of a harveyi clade bacterium isolated from lolliguncula brevis squid

Length–weight relationship and condition factor for 7 loliginid squid species in Mexican waters

The length–weight relationship and the condition factor are key parameters in stock assessment. Despite the fisheries potential loliginid squids have in Mexico, the group is scarcely known and no formal management has been implemented. A total of 1,105 squids captured on the Pacific and Atlantic coasts of Mexico were measured to estimate length–weight relations and condition factors. Except for Lolliguncula brevis and Lolliguncula argus, all species showed negative allometric growth. The 2 species with isometric growth showed a poor condition, according to Fulton’s condition factor, and the rest of the species were in good health, according to the relative condition factor. The type of growth exhibited by the species identified in this study could be associated with their swimming habits or otherwise be affected by the same variables that determine the type of growth of other squid found in Mexican waters. The parameters evaluated in this research are now available for incorporation in further fishery stock assessment models for loliginid squids.

Taxonomic considerations of squids of the family Loliginidae (Cephalopoda: Myopsida) supported by morphological, morphometric, and molecular data

The taxonomy of squids in the family Loliginidae Lesueur, 1821 is complicated due to their inconsistent descriptions which hamper identification at the species level. In this study, a taxonomic revision of loliginid squids from the northwestern Atlantic was carried out considering morphological, molecular, and morphometric characteristics. Squid were collected in four oceanographic cruises along the coast of Tamaulipas, Gulf of Mexico during the period of 2012 to 2014. Museum (NMNH) specimens (type and non-type material) of the species reported for this area were also considered. The morphological attributes described for each species allowed us to confirm the identity of Doryteuthis pealeii (Lesueur, 1821), Lolliguncula brevis (Blainville, 1823), and males of Doryteuthis pleii (Blainville, 1823); the identification of females of D. pleii and Doryteuthis roperi (Cohen, 1976) (the latter only represented by museum material) was not achieved because of the high interspecific similarity. Three genetic clades were detected with COI sequences associated with each of the three field-collected species that were identified morphologically, including the unidentified females, which were recognized as D. pleii. The morphometry of these three groups was addressed by canonical variate analysis, which supported the interspecific differences. A multivariate analysis of variance was conducted for D. roperi and D. pleii due to their high level of morphological similarity. This analysis indicated significant differences; therefore, it did not allow to confirm if D. roperi is a synonym of D. pleii.

Mollusk bycatch in trawl fisheries targeting the Atlantic seabob shrimp Xiphopenaeus kroyeri on the coast of Sergipe, northeastern Brazil

The malacofauna bycatch of sea-bob shrimp Xiphopenaeus kroyeri (Heller, 1862) trawl fisheries on the coast of Sergipe was studied for 5 years. The malacofauna bycatch considered was obtained in nine oceanographic sampling campaigns carried out between May 1999 and June 2003 in 18 stations distributed in six transects along depths of 10, 20 and 30 m. A total of 2,669 individuals of mollusk belonging to 54 species were captured on the 18 sea-bob shrimp trawl stations carried out along the coast of Sergipe. The considerable richness of mollusks was composed by 19 families and 31 species of gastropods, 12 families and 19 species of bivalves and 2 families and 4 species of cephalopods. The highest abundance were observed at stations 13 (373 individuals) and 16 (685 individuals) that represents the lowest depth (10 m) and the richness was higher at stations 15 and 12 (17 and 11 species, respectively) both located at the highest depth (30 m). Cephalopods had high frequency of occurrence being collected in all the stations and by far the most abundant group with a total of 2,488 individuals captured. On the other hand, gastropods (with 142 individuals found in 83.3% of stations) and bivalves (about 1% of the individuals collected) contribute with a much smaller percentage of individuals captured. Lolliguncula brevis (Blainville, 1823) was most representative cephalopod in number and frequency of occurrence. Arcidae, Conidae, Muricidae and Strombidae were the families with the higher number of species in the trawl-fishery. Among bivalves, Pitar arestus (Dall & Simpson, 1901) and Spathochlamys benedicti (Verrill & Bush [in Verrill], 1897) were the species with higher frequency of occurrence. Although the considerable sample effort and a number of mollusks captured as bycath, the richness estimators indicated that the species richness could increase with additional sampling effort in the study area. The present study expands the taxonomic alpha knowledge on the mollusk bycatch of sea-bob shrimp trawl fisheries on the northeastern coast of Brazil. However, it is of crucial importance to assess urgently the negative impacts of the sea-bob shrimp trawl fisheries on the benthic community of the entire coast of Brazil.

Multivariate approach for identifying environmental indicator species in estuarine systems

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 611:19-29 (2019) - DOI: https://doi.org/10.3354/meps12864 Multivariate approach for identifying environmental indicator species in estuarine systems Wen Y. Lee1, Nathan L. Kuhn2,* 1Ecosystem Resources Program, Coastal Fisheries Division, Texas Parks and Wildlife Department, Austin, TX 78744, USA 2Research and Technical Program, Wildlife Division, Texas Parks and Wildlife Department, Austin, TX 78744, USA *Corresponding author: nathan.kuhn@tpwd.texas.gov ABSTRACT: Over time, several indices have been developed for assessing estuarine environmental conditions. In many cases, these indicators were chosen at least partly based on human value judgements that may or may not be justified or defensible. We present a new, 2-step multivariate approach that impartially identifies a suite of ecological indicators and then determines their relationship to environmental conditions in San Antonio Bay, Texas. A total of 12 fisheries indicator species were identified by the PRIMER BEST analysis procedure, including Leiostomus xanthurus, Bairdiella chrysoura, Pogonias cromis, Portunus gibbesii, Callinectes similis, Ictalurus furcatus, Harengula jaguana, Polydactylus octonemus, Lolliguncula brevis, Macrobrachium ohione, Opisthonema oglinum, and Libinia dubia. This suite of indicators showed the highest rank correlation with variation in the environmental variables measured. Subsequent redundancy analysis of the relationship between these indicators and environmental variables revealed salinity as the most influential variable shaping the indicator assemblage, with turbidity the second most influential. When freshwater inflow increased or salinity was low, I. furcatus, M. ohione, and O. oglinum were at their highest relative numbers in the assemblage; conversely, when salinity was high, L. brevis, L. dubia, and C. similis were at their highest relative abundances. Additionally, the euryhaline species L. xanthurus and B. chrysoura were negatively related to water turbidity. The 2-step analysis presented provides a statistically robust way to impartially identify biological indicators most responsive to the environmental variables of interest, and thus provides managers with a robust method for monitoring the effects of their management actions. KEY WORDS: Indicator assemblages · Estuarine condition · Salinity · Turbidity · Multivariate analysis · Texas Full text in pdf format PreviousNextCite this article as: Lee WY, Kuhn NL (2019) Multivariate approach for identifying environmental indicator species in estuarine systems. Mar Ecol Prog Ser 611:19-29. https://doi.org/10.3354/meps12864 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 611. Online publication date: February 14, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Do squid breathe through their skin?

Squid are thought to obtain a large portion of their oxygen via simple diffusion across the skin in addition to uptake at the gills. Although this hypothesis has support from indirect evidence and is widely accepted, no empirical examinations have been conducted to assess the validity of this hypothesis. In this study, we examined cutaneous respiration in two squid species, Doryteuthis pealeii and Lolliguncula brevis, using a divided chamber to physically separate the mantle cavity and gills from the outer mantle surface. We measured oxygen consumption and ammonia excretion rates in the two compartments and found that, at rest, squid only obtain enough oxygen cutaneously to meet the demand of the skin tissue locally (12% of total) and excrete little ammonia across the skin. The majority of oxygen is obtained via the traditional branchial pathway. In light of these findings, we re-examine and discuss the indirect evidence that has supported the cutaneous respiration hypothesis.

New approaches for assessing squid fin motions: coupling proper orthogonal decomposition with volumetric particle tracking velocimetry.

Squid, which swim using a coupled fin/jet system powered by muscular hydrostats, pose unique challenges for the study of locomotion. The high flexibility of the fins and complex flow fields generated by distinct propulsion systems require innovative techniques for locomotive assessment. For this study, we used proper orthogonal decomposition (POD) to decouple components of the fin motions and defocusing digital particle tracking velocimetry (DDPTV) to quantify the resultant 3D flow fields. Kinematic footage and DDPTV data were collected from brief squid, Lolliguncula brevis [3.1-6.5 cm dorsal mantle length (DML)], swimming freely in a water tunnel at speeds of 0.39-7.20 DML s-1 Both flap and wave components were present in all fin motions, but the relative importance of the wave components was higher for arms-first swimming than for tail-first swimming and for slower versus higher speed swimming. When prominent wave components were present, more complex interconnected vortex ring wakes were observed, while fin movements dominated by flapping resulted in more spatially separated vortex ring patterns. Although the jet often produced the majority of the thrust for steady rectilinear swimming, our results demonstrated that the fins can contribute more thrust than the jet at times, consistently produce comparable levels of lift to the jet during arms-first swimming, and can boost overall propulsive efficiency. By producing significant drag signatures, the fins can also aid in stabilization and maneuvering. Clearly, fins play multiple roles in squid locomotion, and when coupled with the jet, allow squid to perform a range of swimming behaviors integral to their ecological success.

Distribution patterns of loliginid squid paralarvae in relation to the oceanographic features off the South Brazil Bight (22°–25°S)

AbstractLoliginid squids constitute marine resources of increasing importance in shelf ecosystems off the coast of South Brazil. However, the existing information and knowledge about the occurrence of early‐life stages and causes of distributional patterns are insufficient. Here, we have revisited Brazilian historical plankton samples obtained from 11 oceanographic surveys to identify paralarvae and their abundances over time. The study area and time period cover the region between Cabo de São Tomé (22°S) and Cananéia (25°S) at depths down to 200 m from 1991 to 2005. Of the 246 paralarvae quantified, ~50% were identified to the genus or species level, including Doryteuthis spp. (D. sanpaulensis and D. plei), Lolliguncula brevis and a single specimen of Pickfordiateuthis pulchella. Paralarval occurrence and abundance peaked in different areas and were associated with distinct oceanographic conditions: D. sanpaulensis occurred in the northern region associated with cold waters and upwelling events, D. plei occurred primarily in the southern region of the study area and in warmer waters, and L. brevis was found in shallow and low salinity waters in the estuarine region off the coast of Santos. Overall, the highest abundance of paralarvae occurred in the nearshore, northernmost areas during summer, and this can be associated with the observed retention mechanisms caused by local circulation, seasonal upwelling, the intrusion of nutrient‐rich waters, and spawning peaks. The present study provides new information and evidence for loliginid patterns in the area that may potentially be useful for better understanding the recruitment patterns and fishery assessments of squid populations.

Turning performance of brief squid Lolliguncula brevis during attacks on shrimp and fish.

Although squid are generally considered to be effective predators, little is currently known of how squid maneuver and position themselves during prey strikes. In this study, high-speed video and kinematic analyses were used to study attacks by the brief squid Lolliguncula brevis on both shrimp and fish. Squid attack success was high (>80%) and three behavioral phases were identified: (1) approach, (2) strike and (3) recoil. Lolliguncula brevis demonstrated greater maneuverability (i.e. a smaller length-specific turning radius) and employed more body adjustments (i.e. mantle angle posturing) during approaches toward shrimp versus fish. Squid exhibited higher linear approach/strike velocities and accelerations with faster-swimming fish prey compared with slower shrimp prey. Agility (i.e. turning rate) during prey encounters was comparable to performance extremes observed during non-predatory turns, and did not differ according to prey type or distance. Despite having the ability to modulate tentacle extension velocity, squid instead increased their own swimming velocity rather than increasing tentacle velocity when targeting faster fish prey during the strike phase, but this was not the case for shrimp prey. Irrespective of prey type, L. brevis consistently positioned themselves above the prey target prior to the tentacle strike, possibly to facilitate a more advantageous downward projection of the tentacles. During the recoil, L. brevis demonstrated length-specific turning radii similar to those recorded during the approach despite vigorous escape attempts by some prey. Clearly, turning performance is integral to prey attacks in squid, with differences in attack strategy varying depending on the prey target.

Turning performance in squid and cuttlefish: unique dual-mode, muscular hydrostatic systems.

Although steady swimming has received considerable attention in prior studies, unsteady swimming movements represent a larger portion of many aquatic animals' locomotive repertoire and have not been examined extensively. Squids and cuttlefishes are cephalopods with unique muscular hydrostat-driven, dual-mode propulsive systems involving paired fins and a pulsed jet. These animals exhibit a wide range of swimming behavior, but turning performance has not been examined quantitatively. Brief squid, Lolliguncula brevis, and dwarf cuttlefish, Sepia bandensis, were filmed during turns using high-speed cameras. Kinematic features were tracked, including the length-specific radius of the turn (R/L), a measure of maneuverability, and angular velocity (ω), a measure of agility. Both L. brevis and S. bandensis demonstrated high maneuverability, with (R/L)min values of 3.4×10(-3)±5.9×10(-4) and 1.2×10(-3)±4.7×10(-4) (mean±s.e.m.), respectively, which are the lowest measures of R/L reported for any aquatic taxa. Lolliguncula brevis exhibited higher agility than S. bandensis (ωa,max=725.8 versus 485.0degs(-1)), and both cephalopods have intermediate agility when compared with flexible-bodied and rigid-bodied nekton of similar size, reflecting their hybrid body architecture. In L. brevis, jet flows were the principal driver of angular velocity. Asymmetric fin motions played a reduced role, and arm wrapping increased turning performance to varying degrees depending on the species. This study indicates that coordination between the jet and fins is important for turning performance, with L. brevis achieving faster turns than S. bandensis and S. bandensis achieving tighter, more controlled turns than L. brevis.

Multiple sensory modalities used by squid in successful predator evasion throughout ontogeny.

Squid rely on multiple sensory systems for predator detection. In this study we examine the role of two sensory systems, the lateral line analogue and vision, in successful predator evasion throughout ontogeny. Squid Doryteuthis pealeii and Lolliguncula brevis were recorded using high-speed videography in the presence of natural predators under light and dark conditions with their lateral line analogue intact or ablated via a pharmacological technique. Paralarval squid showed reduced escape responses when ablated; however, no differences were found between light and dark conditions in non-ablated paralarvae, as was previously shown in juveniles and adults, indicating that the lateral line analogue is integral for predator detection early in life. However, vision does play a role in survival because ablated squid in dark conditions had lower levels of survival than all other treatments. Throughout ontogeny, squid oriented themselves anteriorly towards the oncoming predator, maximizing sensory input to the lateral line analogue system and providing better positioning for tail-first escape jetting, the preferred escape mode. Ablated juveniles and adults had lower response times, escape velocities and peak acceleration than non-ablated individuals, indicating that the lateral line analogue enables squid to respond quicker and with more powerful jets to a predator and maximize escape success. Our findings reveal that the lateral line analogue plays a role in predator detection and successful escape response at the earliest life stages, and continues to contribute to successful evasion by aiding visual cues in juvenile and adult squid.

Molecular Phylogeny of the Genus Lolliguncula Steenstrup, 1881 Based on Nuclear and Mitochondrial DNA Sequences Indicates Genetic Isolation of Populations from North and South Atlantic, and the Possible Presence of Further Cryptic Species

Squid of the genus Lolliguncula Steenstrup, 1881 are small bodied, coastal species capable of tolerating low salinity. Lolliguncula sp. are found exclusively in the New World, although only one of the four recognized species (Lolliguncula brevis) occurs in the Atlantic Ocean. Preliminary morphological analyses suggest that Lolliguncula brevis populations in the North and South Atlantic may represent distinct species. The principal objective of the present study was to verify the phylogenetic relationships within the genus and test for the presence of possible cryptic species. Both gene and species tree topologies indicated that Lolliguncula brevis specimens from the North and South Atlantic represent distinct phylogenetic clades. In contrast with previous studies, L. panamensis was identified as the basal species of the genus. Our results provide important insights into the phylogenetic relationships among the Lolliguncula specimens analyzed, and confirm the genetic separation of Lolliguncula brevis populations of the North and South Atlantic at the level of sister species.

Lateral line analogue aids vision in successful predator evasion for the brief squid, Lolliguncula brevis.

Cephalopods have visual and mechanoreception systems that may be employed to sense and respond to an approaching predator. While vision presumably plays the dominant role, the importance of the lateral line analogue for predator evasion has not been examined in cephalopods. To test the respective roles of vision and the lateral line analogue, brief squid, Lolliguncula brevis, were observed in the presence of summer flounder, Paralichthys dentatus, under light and dark conditions with their lateral line analogue intact and ablated. Hair cell ablation was achieved through a pharmacological technique used for the first time on a cephalopod. The proportion of predator-prey interactions survived was significantly higher in the light non-ablated and light ablated groups compared with the dark ablated group. The mean number of interactions survived varied across treatment groups with the light non-ablated group having significantly more success than the light ablated, dark non-ablated and dark ablated groups. These findings demonstrate that although vision is the primary sense, the lateral line analogue also contributes to predator evasion in squid.

Morphological and morphometric variability of the squid Lolliguncula brevis (Mollusca: Cephalopoda) in Brazilian waters: evidence for two species in the western atlantic?

Morphological and morphometric variability of the small-sized coastal squid Lolliguncula brevis was assessed along the largest part of its latitudinal range in the southern hemisphere, off the Brazilian coast (8º S - 27º S). A general homogeneity in form was found throughout the entire latitudinal range. In terms of body proportions, no latitudinal gradients were evident, but a few local "morphotypes" could be distinguished. The distinctive egg mass morphology, and size and form features, including a hectocotylus 20-40% longer than the opposing ventral arm and the presence of suckers on the buccal membrane, indicated that Lolliguncula from northern and southern hemispheres might comprise two different taxa.

Pupil light reflex in the Atlantic brief squid, Lolliguncula brevis

Coleoid behavioral ecology is highly visual and requires an eye capable of forming images in a variety of photic conditions. A variable pupil aperture is one feature that contributes to this visual flexibility in most coleoids, although pupil responses have yet to be quantitatively documented for squid. The pupil light reflex (PLR) of the Atlantic brief squid, Lolliguncula brevis, was analyzed by directly exposing one eye of individual squid to light stimuli of varying irradiance and imaging the reflex, while simultaneously recording from the opposite, indirectly stimulated eye to determine whether the constriction was consensual between eyes. A PLR was measured in L. brevis, with an asymmetrical constriction observed under increasing irradiance levels that was not consensual between eyes, although a response of some level was observed in both eyes. Response thresholds ranged between 12.56 and 12.66 log photons cm(-2) s(-1). The PLR was rapid and dependent upon the stimulus irradiance, achieving half-maximum constriction within 0.49-1.2 s. The spectral responsivity of the PLR was analyzed by measuring the magnitude of the reflex in the eye directly stimulated by light of equal quantal intensity at wavelengths from 410 to 632 nm. The responsivity curve showed a maximum at 500 nm, indicating the eye is especially well suited for vision at twilight. These results, when considered in the context of the ambient light characteristics, show that the PLR of L. brevis contributes to a dynamic visual system capable of adjusting to the highly variable composition of light in its estuarine habitat.

Prey consumed by Guiana dolphin Sotalia guianensis (Cetacea, Delphinidae) and franciscana dolphin Pontoporia blainvillei (Cetacea, Pontoporiidae) in an estuarine environment in southern Brazil

The present study provides information about the diet of sympatric populations of small cetaceans in the Babitonga Bay estuary. This is the first study on the diet of these species in direct sympatry. The stomach contents of seven Guiana dolphins Sotalia guianensis and eight franciscanas Pontoporia blainvillei were analyzed. The prey of both cetaceans was mostly teleost fishes, followed by cephalopods. We identified 13 teleost fishes as part of the diet of the franciscanas, and 20 as part of the diet of Guiana dolphins. Lolliguncula brevis was the only cephalopod recorded, and was the most important prey for both cetaceans. Stellifer rastrifer and Gobionellus oceanicus were also important for franciscana, so as Mugil curema and Micropogonias furnieri were important for Guiana dolphins. Stellifer rastrifer and Cetengraulis edentulus were the fishes with the highest frequency of occurrence for franciscana (50%), while Achirus lineatus, C. edentulus, S. brasiliensis, Cynoscion leiarchus, M. furnieri, M. curema, Diapterus rhombeus, Eugerres brasilianus and G. oceanicus showed 28.6% of frequency of occurrence for Guiana dolphins. Franciscanas captured greater cephalopods than the Guiana dolphins in both total length (z= -3.38; n= 40; p< 0.05) and biomass (z = -2.46; n = 40; p<0.05). All of the prey species identified occur inside the estuary, which represents a safe habitat against predators and food availability, reinforcing the importance of the Babitonga Bay for these cetacean populations.