Squat Lobster Research Articles

New records of the squat lobster genus Munidopsis Whiteaves, 1874 (Crustacea, Decapoda, Munidopsidae) from the deep sea off Taiwan.

Two species of the squat lobster family Munidopsidae, Munidopsisalbatrossae Pequegnat & Pequegnat, 1973 and M.pycnopoda Baba, 2005, are reported from Taiwan for the first time based on specimens collected from lower bathyal depths. The Taiwanese material of M.pycnopoda also represents the first record of the species from the Pacific Ocean and greatly extends this species' geographical range from the western Indian Ocean to western Pacific. The giant Munidopsis specimen from Taiwan is identified as M.albatrossae mainly by DNA barcoding even though M.albatrossae and M.aries (A. Milne-Edwards, 1880) are both morphologically and genetically extremely similar.

Squat lobsters of the superfamily Chirostyloidea (Decapoda: Anomura) from seamounts on the Nishi-Shichito and Mariana ridges, North-West Pacific off Japan, with descriptions of two new species.

A small collection of chirostyloid squat lobsters was studied, collected from seamounts on the Nishi-Shichito, West Mariana, and Central Mariana ridges, which have been collectively designated as marine protected areas (MPAs) of Japan. Specimens were collected using a remotely operated vehicle (ROV). Four species belonging to three families were identified, of which two are new to science: Uroptychus medius n. sp. (Chirostylidae), Eumunida smithii Henderson, 1885, E. treguieri de Saint Laurent & Poupin, 1996 (Eumunididae), and Sternostylus spiniger n. sp. (Sternostylidae). Identities of those species were assessed using an integrative approach based on morphological comparison and genetic analysis of two mitochondrial markers (COI and 16S rRNA genes). The two species of Eumunida represent the first records from Japanese waters.

The Chirostyloidea of the Northeastern Pacific: Host Associations, Range Extensions and a New Species (Decapoda: Anomura).

Four species of chirostyloid squat lobsters, including a new species and a range extension are reported herein from California. Uroptychus nicoleae sp.nov. was collected on a black coral, Lillipathes sp. off San Clemente Island. It is characterized by a rostrum bearing 1 or 2 lateral teeth, the carapace having 5 lateral spines and a belt of 15 spinules on the anterior dorsal surface, and the dactyls of pereopods 2-5 are curved and bearing a continuous row of 6-8 teeth. The new species is morphologically similar to U. bellus of the southwestern Pacific. The color in life is red and pink. Uroptychus occidentalis is reported for the first time off California. The chirostyloids Sternostylus iaspis and S. perarmatus, which also occur off California, are shown in video still images from a remotely operated vehicle. They inhabit antipatharians and soft corals (Primnoidae) and are easily distinguished from species of Uroptychus by their elongate chelipeds and spinose carapaces. We provide northern range extensions for Uroptychus bellus, Sternostylus defensus and Heteroptychus galapagos collected off Costa Rica.

Microplastic sink that cannot be ignored in chemosynthetic organisms

Marine microplastic (MP) pollution is a widespread concern; however, to date, MP pollution in chemoautotrophic ecosystems remains largely unknown. This study focuses on the cold seep in the South China Sea. Two dominant species, namely mussel (Gigantidas platifrons) and squat lobster (Shinkaia crosnieri), were collected for examining the MP pollution. MPs were present in both mussels and squat lobsters with abundances of 0.13 ± 0.04 and 0.17 ± 0.06 items/ind., respectively. MPs were mainly fibrous (62.5 %) and transparent (45.8 %). The main polymer type was polyester (54.2 %). About 86.5 MPs/m2 were found inhabiting mussels and squat lobsters—a value comparable to those reported in benthos. This pilot report on MP pollution in cold-seep species provides key information for studies on MP pollution in chemoautotrophic ecosystems and evidence regarding a potential biological MP sink. The role of cold-seep organisms in MP retention and transport in the regional sea merits further attention.

Chirostyloid and galatheoid squat lobsters (Decapoda: Anomura) from Andaman and Nicobar Islands, India, with three new species

ABSTRACT The squat lobster fauna of the Andaman and Nicobar waters, India is known to be represented by more than 40 species from 19 genera and six families. Seven species, including three new to science, collected from six dedicated surveys of the Fishery Oceanographic Research Vessel Sagar Sampada during 2011–2019 are described. Gastroptychus valdiviae Balss, 1913 is redescribed based on the syntype and the newly collected material. Grimothea krishaha sp. nov. and an unidentified species provisionally assigned to Grimothea Leach, 1820 are reported. These two species of Grimothea differ from known congeners in the spination on the carapace, pleon, antennule, antenna and third maxilliped. Examination of the syntype and newly collected specimen revealed that Munida vigiliarum Alcock, 1901 should be transferred to Leptonida Macpherson and Baba in Machordom et al., 2022. Leptonida vigiliarum comb. nov. is here redescribed. Trapezionida aequispina sp. nov. differs from related species in the spination on the carapace, and in the shape and relative lengths of the second to fourth pereopod dactyli. Trapezionida bharuchai sp. nov. differs from related species in the carapace morphology, the presence of a mesial spine on the antennal peduncle second article, and the armature on pereopods. Leiogalathea sp. does not resemble known congeners in morphological aspects, but because of the poor condition of the unique specimen presently available for study, formal description is deferred in the hope that additional material will be collected. With this report, the number of species reported from the region increases to 47. http://www.zoobank.org/urn:lsid:zoobank.org:pub:A82CE9B3-BF67-4282-97DF-20D37CF02464

New records and species of deep-sea squat lobsters (Galatheoidea, Munidopsidae) from the Hawaiian Archipelago: an integrative approach using micro-CT and barcodes.

The Hawaiian Archipelago remains extensively under-sampled for many marine invertebrate taxa, including squat lobsters. During the last few years, several deep-sea expeditions carried out in the Pacific Ocean have conducted opportunistic collections of specimens and image data from the vicinity of Hawai'i. Here we describe a new species: Munidopsis hawaii sp. nov. and provide new records for Munidopsidae in the Archipelago and its associations. We illustrate and describe the new species using an integrative approach including micro-CT 3D imaging. Phylogenetic analyses of the species collected from seamounts from Hawai'i indicate that the new species represents a divergent lineage compared to morphologically similar species such as M. dispar and M. papanui. We also study the genetic distances for the species recorded in Hawai'i and other populations of the same species in the adjacent West Pacific. Three species are now known in the Hawaiian region. We also compiled identifications from images captured with ROVs in the area. These observations suggest that munidopsid species are common in the deep sea of Hawaiian waters below 1,000 m.

Integrative approach to describe new species of squat lobsters of the genera Heteronida Baba & de Saint Laurent, 1996 and Torbenella Baba, 2008 (Decapoda, Munididae) from the Southwestern Pacific Ocean

Specimens of munidid squat lobsters belonging to the genera Heteronida Baba & de Saint Laurent, 1996 and Torbenella Baba, 2008 were collected in scientific expeditions made by several French cruises along the southwestern Pacific. These specimens were identified as two species (one new) of Heteronida and six species (four new) of Torbenella. The present paper provides systematic accounts of the five new species, along with new locality records of known species shown by this material and color information where available. Molecular data is provided to support the systematic status of each new species. A key to species for each of the genera is also presented.

Spatio-temporal patterns of the crustacean demersal fishery discard from the south Humboldt Current System, based on scientific observer program (2014-2019).

This study summarises six years of spatio-temporal patterns of the discarded demersal community fauna recorded by onboard scientific observer program for both artisanal and industrial crustacean fisheries between 2014 and 2019, from mesophotic to aphotic depths (96 to 650 m) along the southern Humboldt Current System (28-38°S). In this period, one cold and two warm climatic events were observed during the austral summer 2014, 2015-2016 (ENSO Godzilla), and 2016-2017 (coastal ENSO), respectively. Satellite information showed that Chlorophyll-a concentration varied seasonally and latitudinally, associated with upwelling centres, while equatorial wind stress decreased southward of 36°S. Discards were composed of 108 species, dominated by finfish and molluscs. The Chilean hake Merluccius gayi was dominant and ubiquitous (occurrence, 95% of 9104 hauls), being the most vulnerable species of the bycatch. Three assemblages were identified: assemblage 1 (~200 m deep), dominated by flounders Hippoglossina macrops and lemon crabs Platymera gaudichaudii, assemblage 2 (~260 m deep), dominated by squat lobsters Pleuroncodes monodon and Cervimunida johni and assemblage 3 (~320 m depth), dominated by grenadiers Coelorinchus aconcagua and cardinalfish Epigonus crassicaudus. These assemblages were segregated by depth, and varied by year, and geographic zone. The latter represented changes in the width of the continental shelf, increasing southward of 36°S. Alpha-diversity indexes (richness, Shannon, Simpson, and Pielou) also varied with depth and latitude, with higher diversity in deeper continental waters (>300 m), between 2018-2019. Finally, at a spatial scale of tens of kilometres, and a monthly basis, interannual variations of biodiversity occurred in the demersal community. Surface sea temperature, chlorophyll-a, or wind stress did not correlate with discarded demersal fauna diversity of the crustacean fishery operating along central Chile.

Two new deep-water species of squat lobsters (Crustacea: Anomura: Galatheoidea) from the Central and Southwest Indian Ridge

The high diversity and endemism of benthic species on seamounts are extensively documented. Although the number of squat lobster species from seamount habitats has increased, species from the Central Indian Ridge (CIR) and Southwest Indian Ridge (SWIR) systems remain largely unknown. The hydrothermally active Indian Ridge system harbours potential sites for future Seafloor Massive Sulphides (SMS) mining. Since seabed mining may create a long-lasting impact on the deep-sea ecosystems, it could harm the unique deep-sea life associated with mineral deposits. This study identified two undescribed squat lobster specimens: one from the genus Munidopsis Whiteaves, 1874 from the CIR system in water depths ranging from 1981 to 2033 m, and one from the genus Typhlonida Macpherson & Baba in Machordom, Ahyong, Andreakis, Baba, Buckley, Garcia-Jimenez, McCallum, Rodriguez-Flores & Macpherson, 2022 from the SWIR system in depths ranging from 2070 to 2404 m. Both new species may be distinguished morphologically and genetically based on the partial mitochondrial (mtCOI) gene. To generate baseline environmental and biodiversity data, efforts for accurate sampling and correct identification of biological species are required.

Cosmopolitan abyssal lineages? A systematic study of East Pacific deep-sea squat lobsters (Decapoda: Galatheoidea: Munidopsidae)

Munidopsid squat lobsters are among the most abundant decapods at abyssal depths and the most diverse squat lobster group in the East Pacific region. During recent cruises along the East Pacific, many deep-sea squat lobsters were collected. Among these, we described five new munidopsid species supported both by morphological characters and molecular phylogenetics: Munidopsis girguisi sp. nov., M. nautilus sp. nov., M. testuda sp. nov., M. cortesi sp. nov. and M. hendrickxi sp. nov. We also report new records of several Munidopsis species across the East Pacific that increase the species distribution ranges. Here, we reconstructed the phylogenetic relationships of the East Pacific species in relation to other Galatheoidea using one nuclear and two mitochondrial gene fragment(s); we also performed single locus species delimitation analyses to explore the species status of various East Pacific munidopsid taxa. The new taxa were photographed, illustrated and imaged with micro-computed tomography. The phylogenetic results show that: (1) Janetogalathea californiensis, previously included in the family Galatheidae, nests within Munidopsidae; (2) the phylogenetic position of Phylladiorhynchus and Coralliogalathea as belonging in Galatheidae is not supported; and (3) Munidopsis is paraphyletic, agreeing with recent systematic hypotheses. Short genetic distances and species delimitation analyses suggested that a clade mostly constituted by abyssal species might include fewer species than currently considered, as species show a wider geographic range than previously considered, conforming with traditional hypotheses of cosmopolitanisms in abyssal species. ZooBank: urn:lsid:zoobank.org:pub:CED9EB18-7061-47A7-B2FF-7F1DAFCC7B12.

Spatial distribution of Munida gregaria (Decapoda, Munididae) larvae in the silled Beagle Channel: Insights from spring and autumn surveys

The squat lobster Munida gregaria is an ecologically relevant species in southern South American waters. Nonetheless, fundamental topics regarding its larval ecology remain poorly studied, especially at the southern limit of its distribution area. Here, we investigated the abundance, size, and spatial distribution of M. gregaria larval stages (zoeae I-V and megalopa) in the Beagle Channel, during spring and autumn, and explored their relationships with variations in bathymetry and seawater physico-chemical properties at both sides of the Mackinlay pass sill. Plankton samples were collected from the inner sector of the channel, a fresh water-influenced and semi-enclosed system, to its mouth towards the Atlantic Ocean during four oceanographic cruises (springs of 2014 and 2015 and autumns of 2016 and 2017). Zoeae occurred throughout the study area in both seasons, with lower densities in autumn, whereas megalopae were detected exclusively in spring. The highest larval abundances and all developmental stages were found in the outer sector, where juveniles and adults also occurred. These spatial patterns were consistently observed across the different sampling dates. Contrary to previous reports, the coexistence of zoeae I-V during autumn would indicate that, at least in the outer sector, larvae that hatch late in the summer are able to reach advanced developmental stages. However, it remains unknown whether they fully develop in subsequent months. Significant associations among larval distribution patterns and environmental variables were detected, especially for late stages, which occurred mainly in the westernmost and shallowest part of the outer sector, characterized by highly stratified waters with the warmest bottom temperatures. All together, these results may reflect the effects of variations in local environmental conditions along the channel, related to bottom topography and degree of freshwater/oceanic influence, on larval cohort dynamics, adult reproduction, or both. Larvae hatched in spring were larger than those hatched in summer/autumn for all zoeal stages. Possible explanations for this finding are discussed. This study contributes to our knowledge of M. gregaria larval ecology, which is essential to understand its complex population dynamics in an environmentally complex geographical area, and to better predict its responses to climate change. • Zoeal stages I-V occurred in both spring and autumn. • Larval abundance and stage structure differed west and east of the Mackinlay sill. • Higher larval abundances and all larval stages occurred in the outer sector. • Advanced stages occurred mainly in shallow and highly stratified waters. • Larvae hatched in spring were larger than those hatched in summer-autumn.

Approaching the Ecological Role of the Squat Lobster (Munida gregaria) and the Fuegian Sprat (Sprattus fuegensis) in the Francisco Coloane Marine Area (Magellan Strait, Chile) Using a Pelagic Food Web Model

The structure and functioning of the food web of the Francisco Coloane Marine Area in the Magellan Strait, Chile, was quantified, with an emphasis on identifying the ecological role of the squat lobster (Munida gregaria) and the Fuegian sprat (Sprattus fuegensis). Food web indicators, the trophic level, and centrality indices were estimated using Ecopath with Ecosim. Dynamic simulations were carried out to evaluate the ecosystem impacts of biomass changes in squat lobster and Fuegian sprat. The model calculated a total ecosystem biomass of 71.7 t km-2 and a total primary production of 2450.9 t km-2 year-1. Squat lobster and Fuegian sprat were located in specific trophic levels of 2.3 and 2.7, respectively. Squat lobster reduction produced a decrease in the biomass of red cod (42-56%) and humpback whales (25-28%) and Fuegian sprat reduction a decrease in penguins (15-37%) and seabirds (11-34%). The Francisco Coloane Area is an immature ecosystem with productivity and energy flows values within those reported for productive ecosystems; the role of the squat lobster seems to be related to the structure of the food web, and the role of the Fuegian sprat seems to be related to the functioning of the ecosystem and to the energy transfer to top predators.

Habitat utilization, demography, and behavioral observations of the squat lobster, Eumunida picta (Crustacea: Anomura: Eumunididae), on western North Atlantic deep-water coral habitats

Deep-sea coral habitats, comprising mostly Lophelia pertusa (Linnaeus 1758), are well developed on the upper and middle continental slope off the southeastern United States (SEUS). These habitats support a diverse and abundant invertebrate fauna, yet ecology and biology of most of these species are poorly known. Ten cruises conducted off the SEUS (Summer–Fall; Cape Lookout, NC–Cape Canaveral, FL) from 2000 to 2005, and in 2009 provided an opportunity to investigate abundance and distribution of Eumunida picta Smith1883, a large-sized species of squat lobster commonly associated with these deep-water coral habitats. Video analysis from 70 manned-submersible dives documented occurrence, density, location on the coral colony, and behavioral observations for 5774 individuals of E. picta. Individuals collected (n = 178) from coral and adjacent habitats (e.g., rubble, soft sediments) were measured and their sex determined. Males and females were comparable in size (to 53.5 mm carapace length) and exhibited a sex ratio of approximately 1:1. Eumunida picta were most frequently observed as solitary individuals on high-profile coral matrix and were noted only infrequently on coral rubble, or rarely on soft substratum. Presence of coral habitat (i.e., live/dead L. pertusa), geographic region within the sampling area, and depth significantly influenced abundances of E. picta. Additionally, coral habitat (dead versus live coral), vertical position on the coral (upper, middle, or lower zone), as well as horizontal position in relation to the coral matrix (outer surface versus embedded in coral matrix) were significant factors influencing E. picta distributions within the coral habitat. More individuals were found on dead versus live coral, and most frequently occurred on the outer surfaces of coral branches located on the upper portion or near the tops of coral colonies. Eumunida picta were most often observed with claws extended into the water column. This unique hunting stance provides this squat lobster the opportunity to capture prey from the water column. An active predator, this species utilizes both pelagic (i.e., fishes, pyrosomes) and benthic (e.g., scavenging and grazing) food resources, and may function as an important trophic link between the water column and the benthos. Although considered a facultative reef associate in the strictest sense of the term, E. picta has a complex and intimate relationship with L. pertusa. Based on observations from dive videos, E. picta is a dominant and ecologically important member of the invertebrate assemblage associated with deep-sea coral habitats off the SEUS. As such, this species figures prominently in the structure and function of this ecosystem.

Two new species of the genus Galathea Fabricius, 1793 (Crustacea: Decapoda: Anomura: Galatheidae) from the Andaman Sea, India

Two new species of the galatheid squat lobster genus Galathea Fabricius, 1793 are described from the Andaman Sea, India. Galathea nicobarica sp. nov. closely resembles G. rubromaculata Miyake & Baba, 1967a, but differs in the armature of the branchial carapace margin and shape of the dactylus of the third maxilliped. Galathea tirmiziae sp. nov. is allied to G. consobrina De Man, 1902 and G. tagaro Macpherson & Robainas-Barcia, 2015, but is distinguished by the merus of the third maxilliped lacking a disto-extensor spine and the proportionally more slender merus of the second pereopod.

Munidopsis geyeri and M. exuta (Crustacea: Munidopsidae): A study of two deep-sea, amphi-Atlantic species that co-occur in the southern Gulf of Mexico

The history of colonization and dispersal of fauna among deep-sea chemosynthetic ecosystems remains enigmatic and poorly understood. The distribution of squat lobsters of the genus Munidopsis Whiteaves, 1874 can be influenced by the rich organic matter and associated organism communities of chemosynthetic ecosystems. The present work analyzed the molecular relationships and morphology of individuals from different populations of Munidopsis exuta Macpherson & Segonzac, 2005 and M. geyeri Pequegnat & Pequegnat, 1970 in such ecosystems along the Atlantic Equatorial Belt, including the Chapopote Knoll, in the southern Gulf of Mexico. Munidopsis geyeri is re-described based on the present findings and reference to the literature. This analysis documented the genetic distances, as well as range of variation in the diagnostic characters that support the separation of M. exuta and M. geyeri. Our results confirm that the two species coexist in seep ecosystems and have an amphi-Atlantic distribution.

Squat lobsters of the genera Raymunida Macpherson & Machordom, 2000 and Munidopsis Whiteaves, 1874 (Decapoda: Anomura: Galatheoidea) from the Indian Exclusive Economic Zone, with descriptions of three new species

ABSTRACT We report four squat lobster species of the genera Raymunida Macpherson and Machordom, 2000 (Munididae) and Munidopsis Whiteaves, 1874 (Munidopsidae) from the Indian Exclusive Economic Zone. The genus Raymunida is recorded for the first time from Indian waters, including a new species R. shraddhanandi sp. nov. and R. vittata Macpherson, 2009 based on material from the Andaman Sea. Raymunida shraddhanandi sp. nov. differs from its closest congener R. formasanus Lin, Chan and Chu, 2004 in the armatures of the anterior branchial carapace region, antennal peduncle and third maxilliped merus, and the length of the fourth pereopod. Two new species of the genus Munidopsis, referred to the Anoplonotus group, are described from the south-western Bay of Bengal and the south-eastern Arabian Sea. Munidopsis bengala sp. nov. and M. kadal sp. nov. are distinguished from all of their allies – M. bruta Macpherson, 2007, M. shulerae Vázquez-Bader, Gracia and Lemaitre, 2014, and M. truculenta Macpherson and Segonzac, 2005 – by the unarmed dorsodistal margin of the third maxilliped merus and the relative length of the antennal peduncle, respectively. http://www.zoobank.org/urn:lsid:zoobank.org:pub:5C724556-6532-41F2-9A6E-8424CAE0F2C6

Multi-sensor observation of a rapidly dispersing micronekton thin layer

Ocean midwaters—areas between the sunlit surface layers and seafloor—comprise the largest habitat on Earth but are among the least understood marine environments. Available sampling platforms (e.g. net systems, moored and shipboard sensors), are often unable to resolve the environmentally-coupled distributions of marine biota throughout the water column over the relevant scales. A deep profiling (1000 m rated) stereo camera was operated in tandem with a split-beam five channel fisheries echosounder to record midwater scattering layers in detail across the oxygen minimum zone (OMZ) offshore of Baja California. A computer vision software library was developed to batch process the collected water column imagery and the derived biological information was interpolated with environmental sensor and acoustic backscatter measurements. A large aggregation of the micronekton squat lobster Pleuroncondes planipes (red crab) was described in the imaging and acoustic data. During midday hours, the micronekton were distributed in a thin layer 1.4 m in vertical extent with a sharp lower boundary and having a maximum abundance of at least 10 individuals per m3. The thin layer distribution was tightly coupled to the 1026 kg/m3 isopycnal associated with a high-frequency internal wave. At dusk the crabs redistributed upwards suddenly as a specific mesopelagic scattering layer with a daytime settling depth of 600–800 m migrated through the P. planipes thin layer near the surface. The thin layer was not disrupted by the ascent of an earlier migrating layer suggesting a layer-selective migration response.

Deconstructing the crustacean squat lobster genus

Unravelling the evolutionary history of taxa requires solid delimitation of the traits characterising these. This can be challenging especially in groups with a highly complex taxonomy. The squat lobster family Munididae contains more than 450 species distributed among 21 genera, Munida being the most speciose (~300 species). Previous phylogenetic studies, based on a small part of the diversity of the group, have suggested polyphyletic origins for Munida and the paraphyly of Munididae. Here, we use an integrative approach based on multi-locus phylogenies (two mitochondrial and three nuclear markers) paired with 120 morphological characters, to resolve taxonomic and evolutionary relationships within Munididae. Our study covers ~60% of the family’s known diversity (over 800 specimens of 291 species belonging to 19 of the 21 genera collected from the Atlantic, Indian and Pacific oceans). Using this information, we confirm the validity of most genera, proposing new ones in cases where the genetic analyses are compatible with morphological characters. Four well-defined munidid clades were recovered, suggesting that new genera should be erected in the currently recognised Munididae (three for the genus Agononida and eleven in Munida), and the genus Grimothea is resurrected. A key to all genera of the family is presented. Molecular clock estimates and ancestral biogeographic area reconstructions complement the taxonomic profiles and suggest some explosive diversification within Munididae during the Cretaceous and the Palaeogene. Further anagenetic events and narrow sympatry accounting for changes in distribution indicate a more limited dispersal capacity than previously considered. Our study unravels how diversification may occur in deep waters and further highlights the importance of the integrative approach in accurately delineating species in understanding the history of a family and the factors driving the evolution. ZooBank LSID: urn:lsid:zoobank.org:pub:16A61C4A-8D96-4372-820F-8EBDF179B43C

New Cytochalasin Derivatives from Deep-Sea Cold Seep-Derived Endozoic Fungus Curvularia verruculosa CS-129.

Two new antimicrobial cytochalasin derivatives, 6β,7β-epoxydeoxaphomin C (1) and 12-hydroxydeoxaphomin C (2), a new natural occurring product 24-nor-cytochalasin B (3), together with two related known analogs (4-5) were isolated and identified from an endozoic fungus Curvularia verruculosa CS-129, isolated from the deep-sea squat lobster Shinkaia crosnieri which was collected in cold seep region of south China sea. The structures of new compounds were elucidated on the basis of detailed spectroscopic analysis and ECD calculation. The spectroscopic data of 24-nor-cytochalasin B (3) were reported for the first time. All compounds were tested for their antibacterial activities against human and aquatic pathogenic bacteria.

Changing diets over time: knock-on effects of marine megafauna overexploitation on their competitors in the southwestern Atlantic Ocean

AbstractThis study compares the δ15N values and the trophic position of two seabird species throughout the late Holocene in three regions in the southwestern Atlantic Ocean to assess the hypothesis that the decimation of megafauna led to changes in the trophic position of mesopredators. Modern and ancient mollusk shells were also analyzed to account for changes in the isotopic baseline through time. Results revealed that modern Magellanic penguins have higher δ15N values than their ancient conspecifics in the three regions, after controlling for changes in the isotopic baseline. This was also true for modern Imperial shags compared with ancient unidentified cormorants/shags from the two areas where ancient specimens were recovered (southern Patagonia and the Beagle Channel). Such temporal variability might be caused by three non–mutually exclusive processes: decreased availability of pelagic squat lobster resulting from decreasing primary productivity through the late Holocene, increased availability of small fishes resulting from the sequential depletion of other piscivores (South American fur seal and sea lion and Argentine hake) since the late eighteenth century, and modification of the migratory patterns of Magellanic penguins. Although disentangling the relative contribution of all those processes is impossible at this time, the results reported here demonstrate that the ecology of Magellanic penguins and Imperial shags has undergone major changes since the late Holocene.