Research Article |
Corresponding author: Sebastián Rosenfeld ( rosenfeld.sebastian@yahoo.com ) Academic editor: Eike Neubert
© 2018 Sebastián Rosenfeld, Johanna Marambio, Jaime Ojeda, Juan Pablo Rodríguez, Claudio González-Wevar, Karin Gerard, Tamara Contador, Gemita Pizarro, Andrés Mansilla.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Rosenfeld S, Marambio J, Ojeda J, Rodríguez JP, González-Wevar C, Gerard K, Contador T, Pizarro G, Mansilla A (2018) Trophic ecology of two coexisting Sub-Antarctic limpets of the genus Nacella: Spatio-temporal variation in food availability and diet composition of Nacella magellanica and N. deaurata in the Sub-Antarctic Ecoregion of Magellan . ZooKeys 738: 1-25. https://doi.org/10.3897/zookeys.738.21175
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Interactions between algae and herbivores can be affected by various factors, such as seasonality and habitat structure. Among herbivores inhabiting marine systems, species of the order Patellogastropoda are considered key organisms in many rocky coasts of the world. Nacella species are one of the most dominant macro-herbivores on the rocky shores of the sub-Antarctic ecoregion of Magellan. However, the importance of its key role must be associated with its trophic ecology. The objective of this work was to evaluate spatial and temporal variabilities in the dietary composition of two intertidal Nacella species, considering grazing on macro- (macroalgae) and microscopic (periphyton) food. The composition of periphyton and the availability of macroalgae in the winter and summer seasons were examined at two localities of the Magellanic province, alongside the gut contents of N. magellanica and N. deaurata. The dietary composition differed between the two Nacella species, as well as between seasons and locations. The differences observed in the diet of the two species of Nacella may be mainly due to their respective distributions in the intertidal zone. Both species presented a generalist strategy of grazing, which is relationed to the seasonality of micro- and macroalgae availability and to the variability of the assemblages between the localities. This research was the first to perform a detailed study of the diet of intertidal Nacella species.
Gastropoda , Magellanic Province, herbivory, macroalgae, Nacellidae , periphyton
The structure and dynamics of intertidal ecosystems depend on both abiotic factors (e.g., temperature, substrate, and climate) and biological interactions (e.g., predation, competition, recruitment) (
The main investigations on the ecology of herbivore-algae interactions have been carried out on molluscs of the order Patellogastropoda (
Following this, the current paradigm of herbivory in “limpets” has recently changed (
The rocky shores of the channels and fjords of the Magellan Ecoregion present high environmental heterogeneity, influenced by several geomorphological (e.g., type of substrate;
The present study was carried out in two locations of the Magellanic Province: Puerto del Hambre (53°37'S, 70°54'W), Strait of Magellan and Otway Sound (53°04'S, 71°19'W; Fig.
In order to estimate seasonal variability of algal communities, quantitative sampling of macroalgae was carried out three times throughout the winter season in 2014 (June, July and August) and three times in summer in 2015 (Januar, Februar and March). The NaGISA (Natural Geography in Shores Areas) methodology was used for the quantitative sampling at both study sites, so that the biodiversity of coastal communities was quantified (
In parallel, the periphyton was sampled following the protocol of
In order to evaluate the diet, 10 individuals of each Nacella magellanica and N. deaurata species were collected at each localities from the middle and lower areas of the intertidal levels (Fig.
In the gut content analysis, we used the dietary richness (number of dietary items) of each individual of both Nacella species, and we calculated the occurrence frequency (%) of each item, which is the proportion of individuals containing each recorded item. In addition, the relative abundance (%) of each item in the digestive tract was estimated for each individual collected. The relative abundance of periphyton in the gastric contents was estimated using an inverted microscope and a reticulated glass slide with 50 points, thus recording the number of points of intersection of each taxon, as in
The composition and abundance of micro- and macroalgae in relation to sampling event, species and height on the shore were determined using univariate and multivariate analyses of biodiversity implemented in the program PRIMER 5.0 (
A total of 17 microalgae (Suppl. material
Throughout the study period, the periphyton assemblages found in the gut contents were composed of 27 taxa, among which were diatoms, cyanophytes and dinoflagellates (Table
Systematic list of items found in the gut contents of Nacella species in the winter and summer months, in Puerto del Hambre and Otway Sound, indicating their presence (+).
TAXA | P. Hambre | O. Sound | ||||||
---|---|---|---|---|---|---|---|---|
N. deaurata | N. magellanica | N. deaurata | N. magellanica | |||||
Winter | Summer | Winter | Summer | Winter | Summer | Winter | Summer | |
CYANOBACTERIA | ||||||||
Chroococcus sp. | + | + | + | + | + | + | + | + |
Oscillatoria sp. | + | + | + | + | + | + | + | + |
BACILLARIOPHYTA | ||||||||
Melosira sp. | + | + | + | + | ||||
Coscinodiscus sp. | + | + | + | + | + | + | + | + |
Stephanopyxis sp. | + | |||||||
Biddulphia sp. | + | + | + | + | + | |||
Pinnularia sp. | + | + | + | + | + | + | + | + |
Navicula sp. | + | + | + | + | + | + | + | + |
Gyrosigma sp. | + | + | + | + | + | + | ||
Diploneis sp. | + | + | + | + | + | + | ||
Diploneis sp2. | + | + | ||||||
Plagiotropis sp. | + | + | + | + | + | + | + | + |
Cocconeis sp. | + | + | + | + | + | + | + | + |
Surirella sp. | + | + | + | |||||
Gomphonema sp. | + | + | + | |||||
Cymbella sp. | + | + | + | + | + | + | + | + |
Licmophora sp. | + | + | + | + | + | + | + | + |
Amphora sp. | + | + | + | + | + | |||
Cylindrotheca sp. | + | + | + | + | ||||
Nitzschia sp. | + | + | ||||||
Achnanthes sp. | + | + | + | + | + | + | ||
Rhabdonema sp. | + | + | + | + | + | |||
Grammatophora sp. | + | + | + | + | + | + | + | + |
Fragilaria sp. | + | + | + | + | + | + | ||
MIOZOA | ||||||||
Dinophysis sp. | + | + | ||||||
Protoperidinium sp. | + | |||||||
Prorocentrum sp. | + | + | ||||||
CHLOROPHYTA | ||||||||
Spongomorpha pacifica | + | + | + | + | + | + | + | + |
Ulothrix sp. | + | + | + | |||||
Ulva clathrata | + | |||||||
Ulva lactuca | + | + | + | + | ||||
Ulva prolifera | + | + | ||||||
Ulva sp. | + | + | + | + | ||||
Rhizoclonium sp. | + | + | + | |||||
OCHROPHYTA | ||||||||
Ectocarpus siliculosus | + | + | + | + | + | |||
Caepidium antarcticum | + | + | ||||||
Adenocystis utricularis | + | + | + | + | + | + | ||
Scytosiphon lomentaria | + | + | + | + | ||||
Halopteris funnicularis | + | + | + | + | + | + | ||
Macrocystis pyrifera | + | |||||||
RHODOPHYTA | ||||||||
Acrochaetium sp. | + | + | + | + | + | |||
Nothogenia fastigiata | + | + | + | + | + | + | + | + |
Iridaea chordata | + | + | + | |||||
Sarcothalia crispata | + | + | ||||||
Mazzaella laminaroides | + | |||||||
Grateloupia sp. | + | + | ||||||
Ceramium sp. | + | + | ||||||
Heterosiphonia sp. | + | |||||||
Polysiphonia sp. | + | + | + | + | + | + | ||
Pterosiphonia sp. | + | + | ||||||
Ballia callitricha | + | + | ||||||
Bostrychia sp. | + | + | + | + | + | |||
Plocamium sp. | + | + | ||||||
FORAMINIFERA | ||||||||
Foraminifera indet | + | + | + | + | + | + | + | |
MOLLUSCA | ||||||||
Margarella violacea | + | + | ||||||
Laevilitorina caliginosa | + | + | + | |||||
Eatoniella sp. | + | |||||||
Onchidella marginata | + | |||||||
Mytilus platensis | + | + | + | + | + | + | + | |
Lasaea sp. | + | + | + | |||||
ARTHROPODA | ||||||||
Amphipoda indet | + | |||||||
Ostracoda indet | + | + | + | + | + | + | ||
Notochthamalus scabrosus | + | |||||||
Elminius kingii | + | + | + | |||||
Arachnida indet | + | + | + | + | ||||
Halirytus magellanicus | + | + | + | + | + |
The macroscopic gut contents of both species of Nacella were characterized by 39 taxa, including green, brown and red macroalgae, as well as invertebrates such as foraminifera, molluscs and arthropods (Table
Percentage contribution SIMPER of items in the gut contents of the Nacella species in Puerto del Hambre and Otway Sound for the winter and summer months. The contribution limit was 90% of the total dietary composition. SIMPER analysis shows the dissimilarity between the species of Nacella in the two localities (average dissimilarity in bold and on the bar). The contribution limit was 75% of the total dietary composition. M = Macroalgae (with colours) and I = Invertebrates (with grey scale). Structural hardness of the thallus for macroalgae: th = thin filaments, cf = corticated filaments, clf = cylinder-like form and lm= leathery macrophyte. Functional group for invertebrates: s = sessile and m = mobile.
Finally, the dietary composition varied significantly between N. deaurata and N. magellanica, at each localities and each time (See PERMANOVA, p < 0.05, Suppl. material
Non-metric multidimensional scaling of the dietary composition recorded in the gut contents of the Nacella species in Puerto del Hambre (a, c) and Otway Sound (b, d). a, b correspond to the winter months, and c, d to the summer months. The dashed line indicates the separation between species.
This is the first study to perform a temporal and spatial detailed analysis of the diet of intertidal Nacella species in the Sub-antarctic Ecoregion of Magellan. In general, both localities had a temporal and spatial variation in the composition of periphyton and macroalgae. In terms of diet, our results showed that in the gut contents of N. deaurata and N. magellanica we found a great variety of periphyton, macroalgae and some invertebrates. The results also demonstrated a temporal and spatial influence effect in the diet composition of both species. The diet composition between the two species was also different, mainly due to the highest occurrence of invertebrates in the gut content of N. magellanica and the highest occurrence of corticated filamentous macroalgae in N. deaurata. Here, we discuss how the high temporal and spatial variability of the benthic communities of periphyton and macroalgae affect in the dietary composition of two common grazers that inhabit the Magellan coast.
In general, the average dry biomass of the macroalgae assemblage, per quadrat, at each locality showed a significant increase during the summer months, with the greatest richness and abundance found at the middle intertidal level (Suppl. material
In this study, the gut content of both species of Nacella presented a great variety of periphyton taxa (27 items), among which the most common were 12 taxa of diatoms and the cyanophyte Chroococcus. The rarest items were the dinoflagellates Alexandrium, Dinophysis and Protoperidinium, whose habits are mainly planktonic (
The abundance and composition of benthic diatoms can vary significantly between different micro-habitats within the rocky shore (
Both Nacella species presented a shift in dietary composition in microalgae between the winter and summer months. A similar pattern was observed from the quadrats sampling (habitat composition). This shift in dietary composition is related to the temporal dynamics of periphyton communities, mainly due to the incorporation of different microalgae in the diet during summer. In the Northern Hemisphere, the seasonality in the composition of benthic microalgae has already been observed (
Analyses of gut contents showed greater richness and relative abundance than those observed in the quadrats. Studies in P. vulgata have shown similar results, with a greater variety of diatoms being found in the gut contents (
Variations in the diet of herbivores are generally correlated to food availability (
Average dry biomass (g) of the different functional groups of macroalgae for the winter and summer months in the locality of Puerto del Hambre and Otway Sound and average relative abundance (%) of the different functional groups of macroalgal found in the gut contents of the two Nacella species. The values correspond to means ± DS.
Puerto del Hambre | Macroalgae (g) | N. deaurata (%) | N. magellanica (%) | |||
---|---|---|---|---|---|---|
winter | summer | winter | summer | winter | summer | |
Thin sheet-like forms | 0.64±0.11 | 1.87±0.51 | 3±1 | 8.55±1.9 | 0.55±0.28 | 4.55±1.97 |
Thin filaments | 2.51±1.19 | 3.95±1.01 | 11±2.3 | 21.55±4.6 | 3.22±1.4 | 4.55±2.28 |
Corticated filaments | 1.09±0.3 | 1.67±0.50 | 6±2.6 | 5.11±1.44 | 2.33±1.3 | 2.77±2.43 |
Cylinder-like forms | 1.96±0.65 | 8±2.36 | 1±0.3 | 5.44±1.5 | 5.88±2.56 | 9.11±1.57 |
Coenocytic forms | 0.006±0.0001 | 0.12±0.12 | 0 | 0 | 0 | 0 |
Cushion-like forms | 0.05±0.04 | 0 | 0 | 0 | 0 | 0 |
Leathery macrophyte | 4.34±2.19 | 4.14±1.70 | 0 | 3.33±1.0 | 0.44±0.30 | 3.55±1-29 |
Otway Sound | ||||||
Thin sheet-like forms | 2.14±0.66 | 1.69±0.58 | 0.22±0.15 | 0 | 0.56±0.56 | 1.22±0.49 |
Thin filaments | 0.78±0.62 | 0.42±0.13 | 8±2 | 12.56±3.46 | 1.44±0.73 | 15.56±3.88 |
Corticated filaments | 8.99±2.58 | 2.81±1.04 | 22.67±3.76 | 31±4.86 | 8±2.07 | 3.33±1.57 |
Cylinder-like forms | 3.39±1.19 | 8.59±1.86 | 1.56±0.84 | 8.44±2.89 | 3.33±1.01 | 7.78±1.85 |
Coenocytic forms | 0 | 0.29±0.29 | 0 | 0 | 0 | 0 |
Cushion-like forms | 0 | 0.002±0.002 | 0 | 0 | 0 | 0 |
Leathery macrophyte | 3.56±1.23 | 31.98±7.03 | 0 | 1.22±0.52 | 0 | 1.78±0.59 |
Generalist grazers use an opportunistic strategy in their feeding habits, consuming the most common resources available (
The diet composition in macroscopic items of both Nacella species was varied with a great variety of taxa (37 taxa). Among the most common items ingested by N. deaurata were nine species of macroalgae and some invertebrates such as Laevilitorina caliginosa, Ostracoda indet and Foraminifera indet, while N. magellanica consumed seven species of macroalgae and a large variety of invertebrates, including juveniles of M. platensis, larvae of the chironomids Halirytus magellanicus, Archnida indet, Ostracoda indet and Foraminifera indet. This is the first report of a nacellid species consuming a chironomid (Fig.
Although N. magellanica and N. deaurata cohabit the intertidal zone, they differ markedly in their dietary composition, mainly because N. deaurata consumes a higher diversity of macroalgae (Fig.
The differences observed in the dietary composition of N. deaurata and N. magellanica can also be explained by their vertical distribution in the coastal zone. For example, in the localities of Otway Sound and Puerto del Hambre, N. magellanica presented greater abundance in the middle zone compared to N. deaurata, while N. deaurata presented its highest abundances in the low intertidal zone and in the shallow subtidal (1 meter deep) (
In this study, how the variability in the composition of micro- and macroalgae among intertidal levels (middle and low) and between localities and time plays a fundamental role in the dietary composition of N. magellanica and N. deaurata was studied. This work is the first in the Magellanic Region to address the temporal and spatial characteristics of the diet of Nacella intertidal species, which provides a more complete listing of periphyton, macroalgae and invertebrates present in the diet of these Sub-Antarctic patellogastropods. Finally, it is important to mention that in this study only gut contents were analyzed. Therefore future research using new techniques such as stable isotopes could give a better resolution on the dietary composition that is effectively assimilated by Nacella species.
S.R. would like to thank Mauricio Rosenfeld for all the information provided about the locality of Otway Sound. S.R. and J.M. acknowledge the scholarship received from the Institute of Ecology and Biodiversity (Chile) (ICM P05-002 and PFB-23-2008, respectively) and the Master of Science in Conservation and Management of Sub-Antarctic Ecosystems of the University of Magellan (UMAG). This research was funded by Chile’s National Council for Research in Science and Technology (CONICYT) FONDECYT Program grant 1110875 to A.M., the Millennium Scientific Initiative (grant P05-002 ICM, Chile) and the initiation FONDECYT program grant 11140087 to C.G.-W. The authors would like to thank the people of Patagonia Histórica S. A. for their valuable support to our fieldwork in Puerto del Hambre. We thank Jorgue Terrados and Jaime Rau for their contribution to various phases of the work. We thank Mathias Hüne for the photo of Nacella deaurata. The authors also thank two anonymous referees for their contribution in improving the manuscript.
This works was funded by scholarship received from the Institute of Ecology and Biodiversity (Chile) grant ICM P05-002 to S.R., FONDECYT Program grant 1110875 to A.M., and the initiation FONDECYT program grant 11140087 to C.G.-W. All Authors declares that we have no conflict of interest.
This work was conducted using a local species of invertebrates “mauchos” (Nacella magellanica and Nacella deaurata) as study model, a common limpet species from the southern tip of South America. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. The Instituto de Ecología y Biodiversidad (IEB/15 2015) and Chilean Fishery Service (SERNAPESCA 429/2015) ethic committees approved sampling protocols and experiments. For this, we complied with local legislation and the Convention on Biological Diversity. The species is not protected by the Chilean Fishery Subsecretary and has not been included in the Chilean fishery statistics. Permission to undertake field studies and to collect specimens was issued by the Chilean Fishery Service Director (Carlos Orellana Céspedes), under the technical memorandum (249/2015).
Tables S1–S11
Data type: Occurence of all algae taxa recorded, and Permutation analysis (PERMANOVA) of the composition of algae and gut content of Nacella species.
Explanation note: This is a DOC file with all the temporal information of the occurrence of the algae taxa in both localities, and all the information of the PERMANOVA analyzes used in this study.