The small-scale distribution and resource utilization patterns of hermit crabs life in symbiosis with sea anemones to be investigated in the Aegean Sea. 4 hermit crab species, occupying shells of nine gastropod species, were uncovered in symbiosis with the sea anemone Calliactis parasitica. Shell source utilization trends varied among hermit crabs, with Dardanus varieties utilizing a wide range of shells. The size structure that hermit crab populaces also influenced shell source utilization, v small-sized people inhabiting a larger variety of shells. Sea anemone utilization patterns varied both amongst hermit crab types and among residence shells, with bigger crabs and also shells hosting an enhanced abundance and also biomass the C. Parasitica. The check biometric relationships suggested that small-sized crabs carry, proportionally to your weight, heavier shells and increased anemone biomass than bigger ones. Exception to the over patterns are associated either to local resource availability or come other eco-friendly factors.

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Introduction


Living biology have facility interrelations, which, when referring to close associations in between two species, are characterized using the share term synergy (Henry 1966). Among the many common instances of symbiosis in marine ecosystems is in between cnidarians and also hermit crabs (Decapoda: Anomura); over 100 types of cnidarians have been reported in together associations (Williams and McDermott 2004). Sea anemones (Anthozoa: Actiniaria), though, room the only cnidarian symbionts the are proactively hosted through hermit crabs and also not haphazardly addressed on your gastropod shells throughout larval settlement (Gusmão and also Daly 2010). The development of this symbiosis depends strong on the ease of access of gastropod shells, which carry out both refuge because that hermit crabs and also substratum for the negotiation of sea anemones (Conover 1978; Brooks 1989).

These associations in most instances constitute impressive examples of facultative mutualism, due to the fact that the symbiosis is reciprocally advantageous for both partners (Brooks and Gwaltney 1993; Patzner 2004), and not specifically obligatory (Hazlett 1981). Through the synergy both partners get protection against predators, the hermit crab via the anemone’s nematocysts (Brooks 1989) and also the sea anemone via the hermit crab’s actions of staying clear of or even fighting pets attempting to prey on their attached sea anemones (Brooks and also Gwaltney 1993). The sea anemone gains added benefits through consuming residues from the hermit crab’s food, and by exploring extr resources via its movement as it increases its dispersal capability and gains perfect substratum (Brooks 1989; Gusmão and also Daly 2010). The an excellent importance of the synergy is shown up by the actions of the hermit crabs. Under enhanced levels the predation, lock inhabit shells with much more sea anemones (Ross and also Boletzky 1979), moving the anemones when changing a shell, or they also steal sea anemones from various other crabs (Ross 1979). However, once being starved, hermit crabs may prey on the anemones fastened on their covering (Imafuku et al. 2000).

In spite of the intensive efforts to cover this scientific field, the synergy of sea anemones with hermit crabs is not yet completely understood. The accessible information refers largely to the diversity of the connected epibiotic biology (Stachowitsch 1980; Williams and also McDermott 2004), and also to the behavioral patterns the hermit crabs v respect to sea anemones and also shell source exploitation. A variety of studies manifest different shell resource utilization fads according come size and shell availability (Hazlett 1995; Wada et al. 1997) taking right into account the energetic constraints of delivering a shell (Hahn 1998). Intrinsic covering properties (e.g., shape, weight, spines, facility of gravity, and shell axis) are other important components in shell choice by hermit crabs (Reese 1963; Caruso and Chemello 2009), influencing also the placement of sea anemones top top the covering (Ross and also Boletzky 1979; Brooks 1989). The previous endure in shell an option (Hazlett 1995; Hahn 1998; Gherardi 2006) and the choice of some hermit crabs toward shells of particular gastropod types (Reese 1963; Borjesson and also Szelistowski 1989) have actually been additionally discussed.

Certain morphological characteristics of both sea anemones and also hermit crabs also seem come directly impact the symbiosis, yet the accessible data do not conform to a general common pattern among species. For example, a trend for small, young crabs come utilize bigger shells in ratio to your body size has been proposed (Balasch and also Cuadras 1976; Chintiroglou et al. 1992), while another study reports the large, old crabs use larger and heavier shells (Caruso and Chemello 2009). Considering sea anemone utilization, very few data exist. A single relevant study has actually been performed saying that hermit crabs like small-sized anemones (Christidis et al. 1997). However, this study included a local populace of a solitary hermit crab species; thus, generalization of such fads cannot it is in done.

Considering all the above, the main goal of the present study to be to examine the synergy of sea anemones v hermit crabs (Hc/Sa symbiosis) in the broader area that the Aegean Sea. This was accomplished by providing considerable data on the diversity, distribution, and also biometry of the associated species. Emphasis was given on shell resource and sea anemone utilization patterns, considering the various hermit crab varieties involved, and/or the different types of gastropod shells occupied by the hermit crabs.


Sampling was carried out at Thermaikos Gulf (2005, 2006, 2007, and also 2008), in the north Aegean Sea, and at Spetses (2007 and also 2008), Mykonos (2005 and also 2006), and also Crete (2006 and 2007) islands, in the southern Aegean Sea (Fig. 1). Eight randomly selected station were situated in the north Aegean Sea, in i m sorry the sea bottom is composed of maerl bed (T1 35 m depth), seagrass grasslands (T2 40 m, T3 20 m, T4 20 m, and T6 40 m), or dirt (T5 55 m, T7 40–60 m, and also T8 75–95 m). Nine randomly selected station were located in the southern Aegean Sea, wherein the substratum to be either soft, i.e., sandy through seagrass meadows (M2 25 m, M3 25 m, C3 20 m), or contained rocks and also maerl beds (S1 20 m, M1 35 m, M4 25 m, C1 30 m, C2 20 m, and also C4 35 m).


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Samples, i.e., hermit crabs (with and also without sea anemones), were gathered using trammel nets (five replicates making use of bottom nets trawled over a distance of 3 km, mesh size: 20 mm) and bottom trawling (one draw lasting 4 h and covering a distance of 15 km, mesh size: 20 mm). The latter method was supplied only at two stations in Thermaikos Gulf (T7, T8). The gathered samples were stored separately in 9% formaldehyde.

In the laboratory, every sample was determined to varieties level, and the percent of every hermit crab varieties that hosted sea anemones come the total number of the hermit crabs the this species was assessed. The weight of hermit crabs, gastropod shells, and sea anemones to be estimated, as formalin wet weight, v an electronic scale to the nearest mg, only for those hermit crabs that held sea anemones (Hc/Sa symbiosis). To define the types of Hc/Sa symbiosis, the complying with parameters were calculated: (1) number of hermit crab people in symbiosis with sea anemones, (2) diversity of covering utilization, approximated as the variety of different gastropod shells used by every hermit crab species, and (3) number of hermit crab species utilizing a certain gastropod shell. Multivariate analyses were used to compare the spatial circulation of Hc/Sa synergy types. Non-metric multidimensional scaling ordination (nMDS) via Bray-Curtis distances was used to visualize changes in the ingredient of the Hc/Sa synergy across sampling sites, taking also into account the diversity the gastropod shell fauna. Analysis of similarity (ANOSIM) was supplied to test for distinctions in composition of the Hc/Sa symbiosis between the various species of substratum (i.e., meadows, maerl beds, rocky, and muddy bottoms). Since only seagrass meadows were equally sampled in the northern and southern Aegean Sea, this data were offered to compare the distribution of Hc/Sa symbiosis varieties between the two geographical sectors. Multivariate analyses to be performed using the inside wall package (Clarke and also Gorley 2006).

The populace structure of every hermit crab varieties that hosted sea anemones was analyzed by constructing size-frequency distributions based upon the load of hermit crabs. These data were provided to assess covering utilization of each hermit crab types in relationship to its size.

Multivariate general linear model evaluation of variance (MANOVA) was supplied to check for differences in the abundance and also the biomass of sea anemones associated with hermit crabs follow to hermit crab and gastropod species (two-factor unbalanced design). The Bonferroni check was offered for post hoc comparisons. MANOVAs to be performed utilizing the SPSS software package.

To study the biometric relationships of the participant varieties in the Hc/Sa symbiosis, the relationships between the hermit crab weight and also (1) the weight of the residence shell, which defines the crab’s capability to bring its shell, and (2) the total weight the the held sea anemones, which explains the crab’s ability to collect and also carry sea anemones, were estimated separately because that each hermit crab species found, using linear regression analysis using the strength model, i.e., y = ax b (Sokal and also Rohlf 1987), wherein x = hermit crab weight. A t test with a confidence level of 95% was used to recognize whether this relationships complied with isometry (b = 1) or allometry.

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A full of 546 hermit crabs were accumulated and determined as belonging to eight species. Among these, just 193 people (35.34%), belong to 4 hermit crab species, namely Paguristes eremita, Dardanus arrosor, D. Calidus, and also Pagurus excavatus, brought sea anemones, every belonging come the types Calliactis parasitica. The 313 remaining individuals (57.33%) of the aforementioned varieties and the 40 people (7.33%) of the species Clibanarius erythropus, Pagurus cuanensis, P. Anachoretus, and also Calcinus tubularis were not associated with sea anemones. Thus, four species of Hc/Sa symbiosis were detected, making use of the shells of nine gastropod varieties (Table 1). The types Paguristes eremita and Pagurus excavatus were mostly recorded in Thermaikos samples, if Dardanus types were most generally found in samples indigenous the southern Aegean Sea. The associations the the hermit crabs Paguristes eremita and Dardanus calidus v Calliactis parasitica were the many dominant. The gastropod shells that were most generally used by hermit crabs in synergy with sea anemones were Hexaplex trunculus (32%), Bolinus brandaris (28%), and Phalium granulatum (20%). From these species, B. Brandaris was specifically recorded at Thermaikos, while P. Granulatum to be only uncovered in the southern Aegean Sea.


The composition of the Hc/Sa symbiosis varieties showed an apparent spatial pattern, complying with primarily the location of station (Fig. 2a) and not the habitat type, with the exemption of the muddy bottom at Thermaikos Gulf. ANOSIM results showed non-significant differences in the distribution of the Hc/Sa symbiosis species among habitats (R = 0.43 P = 0.09). Similar results appeared considering also the diversity the shells made use of by every hermit crab (Fig. 2b, ANOSIM results R = 0.20 P = 0.35). While performing the same analyses using data only from seagrass meadows, a clean separation in between the northern and the southern stations to be noticed (Fig. 2c, d), which was far-reaching according to ANOSIM outcomes (R = 0.98 P R = 1 P Fig. 2

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Fig. 3

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