Vertical migration behaviour in the larvae of the shore crab Carcinus maenas from a microtidal system (Gullmarsfjord, Sweden)

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This study aims to improve estimates of dispersal by including information on larval traits, and in particular to explore how larval depth distribution affects connectivity and MPA (marine protected area) functionality in the Baltic Sea. A field survey showed that both invertebrates and fish differed in their larval depth distribution, ranging from surface waters to >100 m. A biophysical model of larval dispersal in the Baltic Sea showed that decreased depth distribution increased average dispersal distance 2.5-fold, decreased coastal retention and local recruitment, and substantially increased connectivity. Together with pelagic larval duration (PLD), depth distribution explained 80% of total variation in dispersal distance, whereas spawning season, and geographic and annual variations in circulation had only marginal effects. Median dispersal distances varied between 8 and 46 km, with 10% of simulated trajectories dispersing 30 to 160 km depending on drift depth and PLD. In the Baltic Sea, the majority of shallow Natura 2000 MPAs are < 8 km in diameter. In the present study, only 1 of the 11 assessed larval taxa would have a recruitment >10% within MPAs of this size. Connectivity between MPAs was expected to be low for most larval trait combinations. Our simulations and the empirical data suggest that the MPA size within the Natura 2000 system is considerably below what is required for local recruitment of most sessile invertebrates and sedentary fish. Future designs of MPA networks would benefit from spatially explicit biophysical models that consider dispersal and connectivity for complex circulation patterns and informed larval traits.

Section: Dispersal Directionmentioning

confidence: 96%

Section: Larval Plankton Surveymentioning

confidence: 99%

Depth distribution of larvae critically affects their dispersal and the efficiency of marine protected areas

Corell¹,

Moksnes²,

Engqvist³

et al. 2012

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“…Tide-related vertical migratory behaviour is present in several brachyuran larvae and is known to influence the direction and extent of horizontal transport in estuarine species, mainly preventing larvae from being retained inside the estuary or the shore (Queiroga et al 1997, DiBacco et al 2001, Bilton et al 2002, Queiroga & Blanton 2005. Nevertheless, Carcinus maenas larvae from Skagerrak lack a tidal rhythm because they inhabit areas where tides are of very small amplitude and have little effect on water circulation (Queiroga et al 2002). Since tidal vertical migration was demonstrated to be inherited in crabs from mesotidal areas as in the British Isles (Zeng & Naylor 1996), a possible effect of Skagerrak isolation may be reflected in the loss of tidal rhythm behaviour in C. maenas larvae from this region.…”

Section: Population Structure Within the Native Range Of Carcinus Maenasmentioning

confidence: 99%

Genetic structure of Carcinus maenas within its native range: larval dispersal and oceanographic variability

Domingues¹,

Creer²,

Taylor³

et al. 2010

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Unravelling the interactions between life-history strategies and oceanography is central to our understanding of gene flow and connectivity in the marine environment. In the present study, we investigated the population genetic structure of the shore crab in its native range in relation to oceanographic characteristics and dispersal potential. Using 10 microsatellite markers over 2 yr, we surveyed 18 locations distributed along ~4200 km within the species native range, from Sweden to Morocco, assessed the population structure by means of F ST and Bayesian clustering analysis and tested the hypothesis of isolation-by-distance (IBD) with a Mantel test. We focused particular attention along a 1200 km stretch of the Iberian Peninsula. We found no evidence of genetic structure (F ST = 0.0001, p > 0.05) along the Iberian coast, and patterns were temporally stable over 2 yr. Across the more extensive geographic spatial scale, overall genetic differentiation was low (F ST = 0.001) but statistically significant (p < 0.001). Furthermore, clustering analysis grouped the samples into 3 genetic units from (1) Sweden, (2) Wales and the Iberian Peninsula and (3) Morocco. While the correlation between genetic and geographic distances was significant, the pattern was not consistent with an IBD pattern. Results suggests that, in the absence of barriers to gene flow, shore crab populations are genetically similar across thousands of kilometres, but isolated populations still may occur within the species native range. Local oceanography and larval behaviour may have a significant influence on the structuring of the populations under study.

“…Larval dispersal can be influenced by both oceanic processes (Sponaugle et al 2002) and intrinsic biological traits, including larval competency (Nozawa & Harrison 2005), swimming ability (Metaxas 2001), and vertical migration behaviours (Raimondi & Morse 2000, Queiroga et al 2002. Importantly, the poor swimming abilities observed in many marine invertebrate larvae make directed horizontal dispersal challenging, particularly into opposing currents (Chia et al 1984, Davis & Butler 1989.…”

Section: Introductionmentioning

confidence: 99%

Larval vertical migration and hierarchical selectivity of settlement in a brooding marine sponge

Whalan¹,

Ettinger-Epstein²,

Battershill³

et al. 2008

Knowledge of larval behaviours of sessile marine invertebrates from release to recruitment and of the role these behaviours play in determining adult distributions is limited. In manipulative experiments using larvae from the Great Barrier Reef sponge Rhopaloeides odorabile, we quantified larval behaviours associated with vertical migration, phototaxis and swimming ability. We also measured settlement responses to cues associated with light, settlement surface micro-topography, coral rubble and biofilms. Following an afternoon release, the majority of larvae (72%) migrated vertically to the surface (light) for 6 to 18 h. After 24 h, 55% of active larvae had moved from the surface to the bottom and maintained this position for up to 54 h before settling. Larvae did not display gregarious settlement patterns, or a preference for settlement surface topographies, but did preferentially settle to light-exposed surfaces. Initial settlement to biofilms or coral rubble was higher than in controls with no cue. However, the transition from initial settlement and attachment to metamorphosis was much higher when treatments comprised a combination of biofilm and coral rubble compared to biofilm-only treatments (49 vs. 9%). Overall, this demonstrates that hierarchical cues contribute to selective settlement. Vertical migration to surface waters facilitates passive dispersal via wind-driven surface currents and contributes to wide-scale dispersal, while a subsequent demersal phase, where larvae actively explore the benthos for settlement sites, enables dispersal over fine, micro-geographic spatial scales.KEY WORDS: Dispersal · Settlement cues · Vertical migration · Metamorphosis · Larvae · Marine invertebrate · Sponge Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 368: [145][146][147][148][149][150][151][152][153][154] 2008 temperature, pressure and gravity all contribute to the settlement process (Young 1995, Underwood & Keough 2000, Maldonado 2006). In addition, cues associated with physical and chemical surfaces affect larval settlement. Surface micro-topography can provide settlement adhesion points (Verran & Boyd 2001) and micro-refuges . Chemical cues have also been widely investigated for marine invertebrate larvae and include cues associated with biofilms of micro-organisms (Pawlik 1992, Hadfield & Paul 2001, Heyward & Negri 1999, Huang & Hadfield 2003, conspecifics (Raimondi 1991, Head et al. 2004, and host organisms (Swanson et al. 2004).Larval dispersal and settlement is well documented for charismatic taxa such as corals, although holistic approaches quantifying the entire pre-settlement phase from larval release to recruitment are rare (Harrison & Wallace 1990, Raimondi & Morse 2000. There are even fewer studies demonstrating these processes in other important benthic taxa including sponges (see review by Maldonado 2006). This is surprising given the remarkable biodiversity of sponges and their global distributions in benthic ecosystems (Hooper & Van So...