Ecology of Sand Beaches at Beaufort, N. C.

1 examined the effects of food availablllty, shell availability and the presence of adults on survlval and duration of the megalopal stage of the lntertldal h e r m~t crabs Pagurus maclaughlinae Garcla-Gomez, Paguristes tortugae Schmitt and Cllhananus vlttatus (Bosc) In the laboratory. I also cons~dei-ed the role of substrate avdilability on C. vlttatus. All species delayed metamorphosis significantly in the absence of empty shells; shells also enhanced megalopal survival In P, maclaughlinae and C. vittatus. Water that had previously housed conspeclflc adults significantly improved megalopal survival and shortened time to metamorphosis in P. maclauglilinae and P. tortugae. Shell-less megalopae of C. vittatus delayed metamorphosis when kept in adult-conditioned water, but metamorphosed more quickly in the presence of sediment. Food availability did not affect the duration of the megalopal stage in P. maclaughlinae or P. tortugae, whereas starved C. vittatus megalopae died in 8 d or less. Although food availability was associated with somewhat enhanced survival in P. tortugae, the mechanism underlying this effect is unknown, since P. tortugae was not observed to feed a s either megalopae or zoeae. As in other species of Pagt~rus, megalopae of P. tnaclaughlinae were not observed to feed, whereas zoeae and juveniles did feed. The differences and similarities in the nature and extent of the delay capabilities of P. maclaughlinae, P. tortugae and C. vittatus appear to reflect the interaction among various aspects of the ecology of the adults a n d energetic constraints on the megalopae.

Section: Substratementioning

confidence: 98%

Delayed metamorphosis in Florida hermit crabs: multiple cues and constraints (Crustacea: Decapoda: Paguridae and Diogenidae)

Aw¹

1996

“…Detrital processing by microbes and meio-and macrofauna on sandy beaches plays a key role in coastal nutrient cycling (Pearse et al 1942, Dugan et al 2011. Bacteria and protozoans rapidly colonize detrital kelp deposits on beaches (Fig.…”

Section: Sandy Beachesmentioning

confidence: 99%

Production and fate of kelp detritus

Krumhansl

Scheibling²

2012

378

341

The flow of detritus between habitats is an important form of connectivity that affects regional productivity and the spatial organization of marine ecosystems. Kelps form highly productive beds or forests that produce detritus through incremental blade erosion, fragmentation of blades, and dislodgement of whole fronds and thalli. Rates of detrital production range from 8 to 2657 g C m −2 yr −1 for blade erosion and fragmentation, and from 22 to 839 g C m −2 yr −1 for loss of fronds and thalli. The estimated global average rate of detrital production by kelps is 706 g C m , accounting for 82% of annual kelp productivity. Detrital production rates are regulated by current and wave-driven hydrodynamic forces and are highest during severe storms and following blade weakening through damage by grazers and encrusting epibionts. Detritus settles within kelp beds or forests and is exported to neighboring or distant habitats, including sandy beaches, rocky intertidal shores, rocky and sedimentary subtidal areas, and the deep sea. Exported kelp detritus can provide a significant resource subsidy and enhance secondary production in these communities ranging from tens of meters to hundreds of kilometers from the source of production. Loss of kelp biomass is occurring worldwide through the combined effects of climate change, pollution, fishing, and harvesting of kelp, which can depress rates of detrital production and subsidy to adjacent communities, with large-scale consequences for productivity.KEY WORDS: Kelp bed · Kelp forest · Connectivity · Detritus · Resource subsidy · Local-regional productivity Resale or republication not permitted without written consent of the publisher

“…For many years, these habitats were labelled as 'harsh' and 'structurally homogeneous environments' and were thought to offer little in terms of habitat diversity, cover or productivity (Pearse et al 1942, Hedgepeth 1957, Springer & Woodburn 1960. Recent evidence suggests, however, that fluctuations in c e r t a~n physical variables such as the degree of wave exposure, sediment particle size and turbidity have a strong influence on the relative abundance of certain species and Inay alter the composition and species richness of surf zone fish assemblages (Hillman et al 1977, Blaber & Blaber 1980, Ta.llmark PL Evans 1986, Romer 1990, Pihl & van der Veer 1992.…”

Section: Introductionmentioning

confidence: 99%

Factors affecting spatial variability in seine net catches of fish in the surf zone of False Bay, South Africa

Bm¹,

Ba²,

Sj³

1996

Ichthyofaunal assemblages at 11 surf zone localities along the perimeter of False Bay South Afnca were sampled by seine netting at monthly intervals between July 1991 and J u n e 1993 Sampllng localit~es were selected to encompass as wide a range of physical vanables as possible incorporatlng sheltered, exposed, sandy and mixed-shore habitats, thus providing a colnprehensive assessment of the factors lnfluenclng surf zone fish assemblages Data collected at each site were averaged over the 2 yr p e i~o d in order to highlight the influence of various physical environnlental vanables on the abundance and co~nmunity structure ot these assemblages Athenr~a brevlceps, Liza rlchardsonii and Rhahdosarg~ls gloh~ceps were numeiically domlnant at all sites together providing between 69 and 99%) of the catches Overall catches of juvenile flsh exceeded that ot adult fish, making up almost 53 of the catch Fish abundance (no ind per 100 m') and number of species recorded at each site ranged from 6 to 199 and from 12 to 31 respectivel) Multivdriate analyses Indicated that the deglee of wave exposure the presencc of emergent rock on the shore dnd turbid~ty were responsible for most of the s p a t~a l vanab~lity in abundance and community structure observed Although of lesser importance abundance of detached macrophytes salinity dnd water temperature also played a role in structuring fish assemblages Species specific preferences for varying combinations of these var~ables are responsible for fluctuations in the structure and overall abundance of assemblages in different a r e a