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MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 155:29-44 (1997) - doi:10.3354/meps155029 Magnitude and fate of the production of four co-occurring Western Mediterranean seagrass species Cebrián J, Duarte CM, Marbà N, Enríquez S We examined the seasonality and magnitude of the leaf-blade, rhizome and root biomass and production, along with the fate of leaf-blade production, of the 4 Mediterranean seagrass species Posidoniaoceanica, Cymodoceanodosa, Zosteranoltii and Zosteramarina in a protected northern Spanish bay (Cala Jonquet, 42° 18.26' N, 3° 18.11' E) to estimate (1) the annual production consumed by herbivores or decomposed by detritivores and (2) the production in excess of consumption and first-year decomposition, which should be an upper limit of long-term burial of refractory detritus. The leaf, rhizome and root biomass of the 4 species displayed a clear seasonal pattern (which is in agreement with past studies), except for that of Z.noltii, which suggested a rapid loss of its production either to herbivores or as detritus. Z.marina and P.oceanica were the most productive species, and transferred to consumers (herbivores and detritivores) about twice the production transferred by C.nodosa and Z.noltii. Most of the production of the 4 species was decomposed by detritivores, which supports the importance of the detritivore food-web in the use and recycling of seagrass production. Consumption of seagrass leaf production by herbivores appeared to be higher for C.nodosa and Z.noltii, the species with the greatest leaf turnover rates, than for Z.marina and P.oceanica. Total heterotrophic use of seagrass production (consumption by herbivores and decomposition by detritivores) accounted for more than 80% of seagrass production in the 4 species. Yet, the excess of production not consumed nor decomposed during the first year ranged over 1 order of magnitude from the most (Z.marina and P.oceanica) to the least productive species (C.nodosa and Z.noltii) and represented a larger percentage of the production of the former species (9.2 and 16.8% respectively) compared with the latter species (about 1.5%). That suggests that Z.marina and P.oceanica may accumulate larger pools of refractory detritus and that their production is recycled more slowly than that of C.nodosa and Z.noltii. These results show marked differences in the fate of production among the 4 Western Mediterranean seagrass species growing in Cala Jonquet and suggest that differences in the leaf turnover rate could contribute to the explanation of differences in the fate of seagrass production, the species with faster-growing leaves losing a higher percentage of production to herbivores and recycling most of the residual detrital production, therefore storing relatively small pools of refractory detritus. Mediterranean seagrasses · Fate of production · Herbivory · Decomposition · Production excess Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 155. Publication date: August 28, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 197:231-240 (2000) - doi:10.3354/meps197231 An experimental test of the occurrence of competitive interactions among SE Asian seagrasses Carlos M. Duarte1,*, Jorge Terrados1, Nona S. R. Agawin1, Miguel D. Fortes2 1Instituto Mediterráneo de Estudios Avanzados (CSIC-UIB), c/Miquel Marqués 21, 07190 Esporles (Mallorca), Spain 2Marine Science Institute, University of the Philippines, Diliman, Quezon City 1101, Philippines *E-mail: ieacdq@clust.uib.es ABSTRACT: The occurrence of competitive interactions among the seagrass species present in a multispecific SE Asian seagrass meadow was tested by the cumulative removal of shoots of an increasing number of seagrass species from the meadow in order of decreasing and increasing resource requirements for plant growth. The removal of shoots of the dominant species Thalassia hemprichii had very few effects on shoot size, shoot density and leaf area index of the extant seagrass species. The shoot density of Enhalus acoroides decreased when T. hemprichii shoots were removed, but that of Syringodium isoetifolium increased when the shoots of all the species with higher resource requirements than itself were removed from the experimental plots. The size of Halophila ovalis shoots decreased by 30% when both T. hemprichii and E. acoroides shoots were removed from the plots. The shoot density of T. hemprichii increased only when the shoots of all the accompanying species were removed from the plots. The results show that species interactions in this multispecific seagrass meadow are asymmetric. The elucidation of the nature of the interactions among seagrass species provides a key to understanding the maintenance of the high biodiversity and production that characterizes pristine SE Asian coastal ecosystems. KEY WORDS: Interspecific competition · Tropical seagrasses · SE Asia Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 197. Publication date: May 12, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 532:101-109 (2015) - DOI: https://doi.org/10.3354/meps11343 Combined effect of warming and infection by Labyrinthula sp. on the Mediterranean seagrass Cymodocea nodosa Ylva S. Olsen1,*, Carlos M. Duarte1,2,3 1The UWA Oceans Institute, University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia 2Department of Global Change Research. IMEDEA (CSIC-UIB), Institut Mediterrani d'Estudis Avançats, Miquel Marquès 21, 07190 Esporles, Spain 3Faculty of Marine Sciences, King Abdulaziz University, PO Box 80207, Jeddah 21589, Saudi Arabia *Corresponding author: ylva.olsen@uwa.edu.au ABSTRACT: Global warming is predicted to alter host-pathogen relationships and increase disease outbreaks in terrestrial and marine environments. We evaluated the effect of warming on the susceptibility of Cymodocea nodosa to infection by Labyrinthula sp. (the causative agent of seagrass wasting disease) by monitoring disease symptoms and seagrass photobiology. Seagrass shoots were incubated at temperatures between 24 and 32°C, encompassing maximum summer seawater temperatures projected for the Mediterranean during the 21st century, and exposed to Labyrinthula sp. for 2 wk. The effect of temperature on pathogen growth was also tested by growing Labyrinthula sp. in liquid medium for 24 h. Disease severity, measured as lesion size, decreased with warming, but the presence of lesions had a negative effect on quantum yield, quantum efficiency, optimum irradiance and the maximum electron transport rate (ETRmax) in adjacent tissue across the full range of temperatures. The direct effect of increased temperature on photochemical efficiency was positive in terms of quantum yield, whereas compensation and optimum irradiances and ETRmax decreased slightly with warming. Warming stimulated Labyrinthula sp. growth up to a threshold of around 26 to 28°C, beyond which cell division and elongation of the ectoplasmic network decreased. At 32°C almost no growth was observed. Our results indicate that warming does not make C. nodosa more susceptible to infection by Labyrinthula sp. and that the disease is unlikely to pose a serious threat to C. nodosa, but that the pathogen is able to persist during forecasted warm periods. KEY WORDS: Wasting disease · Pathogen · Host · Seagrass · Photosynthetic performance · Temperature · Climate change Full text in pdf format PreviousNextCite this article as: Olsen YS, Duarte CM (2015) Combined effect of warming and infection by Labyrinthula sp. on the Mediterranean seagrass Cymodocea nodosa. Mar Ecol Prog Ser 532:101-109. https://doi.org/10.3354/meps11343 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 532. Online publication date: July 21, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

We provide evidence, based on the assessment of bactenal abundance in a series of samples representing geometncally decreasing volumes (5 1 to 0.25 ml), for the existence and scale dependence of patchiness in mixed-layer marine bacterioplankton.Our results demonstrate the existence of strong bacterioplankton patchiness at centimetre scale, the bacterioplankton community appearing as homogeneous when sampling at larger or smaller scales.We also provide, based on the inferred frequency distribution of bacterial densities, a representation of the in situ s p a t ~a l distribut~on of the bacterioplankton population sampled This dlstrlbution depicts the bacterioplankton community as composed of high density (> 107 bacteria ml-l) bacterial patches scattered within a 'matrix' of low bactenal density (105 bacteria ml-l).These results imply that the processes regulating bactenal abundance operate at centimetre scale.

Abstract. One of the major features of the coastal zone is that part of its sea floor receives a significant amount of sunlight and can therefore sustain benthic primary production by seagrasses, macroalgae, microphytobenthos and corals. However, the contribution of benthic communities to the primary production of the global coastal ocean is not known, partly because the surface area where benthic primary production can proceed is poorly quantified. Here, we use a new analysis of satellite (SeaWiFS) data collected between 1998 and 2003 to estimate, for the first time at a nearly global scale, the irradiance reaching the bottom of the coastal ocean. The following cumulative functions provide the percentage of the surface (S) of the coastal zone receiving an irradiance greater than Ez (in mol photons m−2 d−1): SNon-polar = 29.61 − 17.92 log10(Ez) + 0.72 log102(Ez) + 0.90 log103(Ez) SArctic = 15.99 − 13.56 log10(Ez) + 1.49 log102(Ez) + 0.70 log103(Ez) Data on the constraint of light availability on the major benthic primary producers and net community production are reviewed. Some photosynthetic organisms can grow deeper than the nominal bottom limit of the coastal ocean (200 m). The minimum irradiance required varies from 0.4 to 5.1 mol photons m−2 d−1 depending on the group considered. The daily compensation irradiance of benthic communities ranges from 0.24 to 4.4 mol photons m−2 d−1. Data on benthic irradiance and light requirements are combined to estimate the surface area of the coastal ocean where (1) light does not limit the distribution of primary producers and (2) net community production (NCP, the balance between gross primary production and community respiration) is positive. Positive benthic NCP can occur over 33% of the global shelf area. The limitations of this approach, related to the spatial resolution of the satellite data, the parameterization used to convert reflectance data to irradiance, the lack of global information on the benthic nepheloid layer, and the relatively limited biological information available, are discussed.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 119:243-252 (1995) - doi:10.3354/meps119243 Patterns in the photosynthetic metabolism of Mediterranean macrophytes Enríquez, S., Duarte, C. M., Sand-Jensen, K. Here we examine the relationship between the photosynthetic performance of a wide range of Mediterranean marine macrophyte species (5 angiosperms and 18 macroalgae of widely different size and growth form), and several descriptors of the photosynthetic tissue such as thickness, chlorophyll a (chl a) and nutrient (C, N, P) content. The photosynthetic performance of the plants is described by their photosynthesis-irradiance curves, either as continuous functions, or as the individual parameters defining the curves. Our results demonstrate a strong relationship between the photosynthetic efficiency (alpha) measured at low light and the photosynthetic rate at saturating light (Pmax), and show alpha to be closely related to differences in tissue thickness and chl a concentration among the marine macrophytes examined. The interaction between thickness and chl a concentration in the regulation of alpha is parallel to their interaction in the regulation of light absorption properties. Tissue thickness and pigment concentration not only explained variation in individual photosynthetic parameters (Pmax and alpha), but were also able to summarise differences in the response of photosynthesis to irradiance. The strong relationship between tissue thickness and photosynthetic performance lend support to the important adaptive role attributed to the thickness of marine macrophyte tissues in the past. This importance of thickness extends beyond the regulation of plant productivity to the resistance to grazing, mechanical damage and the longevity of the tissue. Considering previous demonstrations of the functional importance of thickness for phytoplankton and for land plants, we suggest the existence of a general relationship between tissue thickness and the photosynthetic performance of photosynthetic organisms. Marine macrophytes . Photosynthetic rates . Thickness . Chlorophyll a . Nitrogen . Phosphorus . Allometric scaling Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 119. Publication date: March 23, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.