Band 56, Heft 5-6

We obtained and analyzed a baseline dataset of Zostera marina (eelgrass) dynamics in three adjacent bays in Nova Scotia, Canada. The field sites were Kejimkujik National Park Seaside (Keji), Port l’Hebert (PH), and Port Joli (PJ). Measures of Z. marina growth and production, including shoot density, aboveground and belowground biomass, and shoot productivity, were sampled monthly for 1 year. Physical parameters, including water temperature, suspended solids, nutrients, ice cover, and algal presence, were also measured. Seasonal cycles in shoot density, leaf length, and aboveground biomass of Z. marina were evident at all sites. Shoots persisted throughout the winter; however, shoot density was lowest at PH and Keji due to ice cover. Belowground biomass at all sites did not show seasonal signals. Greatest differences in measured Z. marina parameters were observed at Keji compared with PH and PJ. Restricted water exchange at Keji caused high water temperatures, low flushing rates, and prolific algal growth, probably resulting in lower shoot densities and biomass than in PH and PJ. Our study provides some of the first data on Z. marina dynamics in the Atlantic Canadian region, and will provide a critical baseline for future comparisons of plant condition and estimates of variability in potential monitoring parameters.

Eelgrass meadows ( Zostera marina ) have been mapped in Troms (Norway), in the temperate northeast Atlantic, north of the polar circle, from 2008 to 2011. In this region, there is little knowledge of the distribution of the eelgrass meadows. Northern Norway has an extensive coastline with many pressures and stakeholders. Old records (back to 1900) have been revisited and new locations surveyed based on a combination of spatial modeling, using digital information on depth, slope, and wave exposure and stakeholder recommendations. The results showed that 42% of the previously mapped locations had disappeared. However, we found Z. marina meadows at seven locations where they had not previously been recorded. Most meadows (66%) were smaller than 10,000 m 2 . The largest meadow covered an area of 325,000 m 2 , and was located in Balsfjorden. The results clearly show that Z. marina is able to form actively growing stands even at ∼70°N. Three of the meadows were first registered over 100 years ago, indicating long-lived stands in stable conditions. This study cannot explain the causes for the observed decline, and only discusses possible relations. The eelgrass meadows are genetically isolated but yet diverse. Management at fjord range level is required to maintain healthy and stable stands of eelgrass meadows in this region.

Tolerance to air exposure should be an important feature in determining the geographic distribution of seaweeds. Two sibling kelp species with contrasting latitudinal distributions were selected to test the relationship between their distribution and air exposure tolerance: Lessonia berteroana distributed between 18° and 30°S and Lessonia spicata , which is found from 29° to 41°S along the Chilean coast. This region presents a latitudinal gradient of environmental variables, which leads to an increase in air exposure as latitude decreases. Therefore, populations of L. spicata are likely to be exposed to lower desiccation levels than those of L. berteroana . To assess adaptation to air exposure, early stages of development of these species were exposed to air daily for 0, 0.5, 1, and 2 h, and the activities of two antioxidant enzymes (ascorbate peroxidase and catalase) were measured. Results showed that L. spicata spores ceased their postgermination development when exposed to 1 and 2 h of air, contrasting with L. berteroana , in which spore development was not abruptly stopped as for L. spicata . In addition, the apparent inactivation of the antioxidant enzyme catalase in both species strongly suggests a lower buffering capacity to an excess of reactive oxygen species (ROS) triggered by air exposure. Thus, air exposure seems an important factor determining the northern geographic limit of L. spicata .

The influence of stresses on the crust phase of Colpomenia bullosa , originally thought to be Ralfsia verrucosa , inhabiting rockpools above the lowest high water on Kainga Reef, SE New South Wales, was investigated. The mean densities of grazing gastropods Nerita atramentosa and Austrocochlea porcata were 107 and 59 animals m -2 , respectively, with no seasonal variation. Some pools were more attractive to Austrocochlea than others. Herbivore impact on C. bullosa crust was assessed by collecting and examining feces and counting the number of crust filaments. Seasonal variations in grazing and in crust cover were not related in a way that would suggest a causal relationship. The calculated annual consumption was 7% of the crust. Grazing probably kept the crust clean of epiphytes. When local conditions isolated the pools from the sea for days, some crusts survived a known salinity of 127 psu and an estimated 175 psu. The crust of C. bullosa on pool sides survived up to 58 h of emersion, but complete drying on pool bottoms was lethal within 14 h presumably as a result of saturating salinity preceding complete drying. UVB-absorbing substances, assumed to be phlorotannins, were released by the crust during pool drying. It is concluded that high temperatures were the likely cause of both the slow growth rate and the high mortality of C. bullosa crust on Kainga Reef in summer.

The distribution of the endemic brown alga Fucus virsoides was assessed along the northern Adriatic coastline. A high-resolution geographic information system database was created using visual census methods to identify the presence and abundance of algae, including the geomorphology of the substrate. Samples of F. virsoides were collected for analysis of the quantitative spatial distribution. The abundance of F. virsoides was related to several environmental variables, including the relative exposure index (REI). The results support the hypothesis that the distribution of F. virsoides in the Gulf of Trieste is influenced mainly by the stability of mediolittoral substrata, wave exposure and the vicinity of freshwater inputs. Populations of this species are widespread in the Gulf of Trieste. Many of them were found growing inside small harbours or along a boatyard, where fluctuations in salinity and nutrient concentrations are frequent. Therefore, we conclude that F. virsoides cannot be considered an ecological indicator for seawater pollution nor for climate change, since it is subjected naturally to high pollution levels and environmental variability.

Sampling of sublittoral macroalgal assemblages was carried out in 1982 and 1999 along the coast of Catalonia (Northwestern Mediterranean, Spain) in order to study long-term changes in species composition. Ordination analysis revealed significant differences in species composition and abundance between the two study periods. The number of stations with indicators of eutrophication, such as species of Chaetomorpha , Cladophora , and Ulva , decreased from 1982 to 1999. This decrease was not balanced by an increase in species typical of pristine environments, such as large perennial brown algae (in particular, Cystoseira mediterranea ), but rather by an increase of stress-resistant species such as Corallina elongata . The observed shifts seem to be driven by the decrease in nutrient loadings in the water column, resulting from the progressive implementation of sewage treatment management in the study region since the mid-1970s.

Land-based sewage pollution is a major threat to the health of near-shore coral reefs. Macroalgal δ 15 N-values are useful indicators for tracking nitrogen sources and sewage input; however, the direct link between δ 15 N-values of macroalgae and the coral condition, including live coral cover, species richness, and juvenile coral density, is unclear. Macroalgal δ 15 N-values of two species, Lobophora variegata and Tricleocarpa oblongata , were measured in Wenchang (northeast Hainan Island, South China Sea) in both the dry and wet seasons, to assess the influence of nitrogen sources and nutrient stress resulting from sewage input or upwelling on the condition of corals. Macroalgal δ 15 N-values showed that shallow stations between the reef and the coast were severely affected by sewage input (e.g., river discharges and aquaculture ponds), whereas deep stations on the outside of the reef were influenced by upwelling-based nutrients. Correlation and redundancy analysis demonstrated that δ 15 N-values of L. variegata had a stronger relation with coral condition than any other environmental parameter (e.g., water quality index, turbidity, and dissolved nutrients), with significant negative correlations in both the dry and wet seasons. Thus, macroalgal δ 15 N-values can be used to determine where nutrient stress is negatively affecting corals, highlighting the links of human activities and coastal upwelling with marine ecosystems.

In recent years (2007–2009), the distribution and associated flora of maerl beds in southern Portugal (Algarve) were investigated by dredging and SCUBA diving (12–30 m depth). The present work provides the first data on the non-coralline crustose flora associated with maerl beds in Portugal. Peyssonnelia bornetii is a new record for Atlantic European coasts, and new records for Portugal are “ Rhododiscus pulcherrimus” (sporophyte phase of Atractophora hypnoides ), Contarinia peyssonneliaeformis , “ Cruoria rosea” (sporophyte phase of Halarachnion ligulatum ), Peyssonnelia armorica , and “Aglaozonia chilosa” (sporophyte phase of Cutleria chilosa ). In addition, the records of three other species ( Hildenbrandia crouaniorum , Peyssonnelia dubyi , and Peyssonnelia harveyana ) completed the distribution gap between the North Iberian Peninsula and the Macaronesian region. The female and carposporangial structures of C. peyssonneliaeformis and P. bornetii are described for the first time. The diversity and species composition observed are compared with previous studies from maerl beds in the northwestern Iberian Peninsula (Galicia) and neighboring areas in the Atlantic Ocean and Mediterranean Sea. In order to facilitate and promote further studies of the crustose flora of subtidal habitats along European coasts, an identification key is provided for the 26 crustose taxa associated with maerl and gravel beds of the Atlantic coast of the Iberian Peninsula.

A new species of Hydrolithon is described from mesophotic habitats, between 30 and at least 76 m depth, off La Parguera, Puerto Rico, and St Thomas, Virgin Islands (Caribbean Sea). Its encrusting thallus covers corals and rocks. Hydrolithon abyssophila sp. nov. is distinctive in developing bisporangia that are about twice as large as its congeners and in lacking both perithallial protuberances and trichocytes in horizontal or vertical groups. It reproduces primarily by uninucleate bispores that presumably recycle the parental phase. Unfertilized carpogonia were observed in one collection suggesting the rare occurrence of gametophytic reproduction in the species.

A finely pinnately branched species of Grateloupia not seen previously in New Zealand was collected in Tauranga, New Zealand, growing on a tug boat. Molecular sequencing data ( rbc L) revealed it to be Grateloupia subpectinata , a species first described from Japan, and also reported as native to Korea and China, and introduced to Britain, France, and Australia. The only species of Grateloupia with morphology similar to G. subpectinata in the New Zealand region is G. prolifera from the Chatham Islands. A sequence of this species was obtained for comparative purposes and found to be distinct from G. subpectinata .

Worldwide, 32 species have been recognized in the genus Neosiphonia . We describe two new species of the genus from Bali, Indonesia, based on morphological and molecular data. Neosiphonia baliana sp. nov. is recognized by having rhizoids cut off from the proximal end of pericentral cells, axes with five pericentral cells, axes ecorticate throughout, the absence of trichoblasts and scar cells, the straight arrangement of tetrasporangia, and spermatangia arising from a basal cell without the production of trichoblasts. Neosiphonia silvae sp. nov. is characterized by having rhizoids cut off from the proximal end of pericentral cells, axes with four pericentral cells, axes ecorticate throughout, production of abundant trichoblasts near the apices, prominent scar cells, an exceedingly prominent apical cell at axis tips, and one or two tetrasporangia per branch. Phylogenetic analyses of rbc L indicated that our N. baliana sp. nov. and N. silvae sp. nov. fall in the genus Neosiphonia , and we distinguish them on the basis of morphological features from other congeneric species.

Does density affect recruitment and growth in the annual, blade phase of Pyropia sp., does self-thinning occur, and does substrate affect recruitment? These questions were investigated in laboratory-cultured Pyropia torta , a naturally occurring species in Alaska with mariculture potential. Three density levels were produced from conchospores. Measurements were made, initially at settlement and germination and, subsequently, at approximately 3-week intervals, in 12 randomly selected cultures from each density level. Settled spores, germlings, or growing blades were counted microscopically and standardized to unit area. Blade surface area was measured microscopically using image analysis software. Three density levels were still distinct at germination, but the high and medium levels were not significantly different. The germination rate of conchospores was highest at the medium density level, suggesting facilitation at moderate densities but inhibition at higher densities. Significant self-thinning occurred at each density level but differed among levels, while overall blade growth was about 10-fold greater at low density than at the other two levels. In a separate experiment, counts of attached spores per unit area on artificial substrate materials were greatest on materials with interstitial spaces large enough to trap spores until they become firmly attached.

During a phytoplankton survey, non-motile (cyst-like) cells were isolated and cultured from the tropical Mexican Pacific, which belong to the thecate dinoflagellate Vulcanodinium rugosum Nézan et Chomérat, recently described from the Mediterranean and recently identified as a source of pinnatoxins in Australia, New Zealand, and Japan. Motile cells and putative cysts were studied by light microscopy and scanning electron microscopy. The most characteristic features of the species agree with a previous description: (i) large and conspicuous apical pore, which extrudes mucilaginous material; (ii) polygonal and striated theca; (iii) ventral, sigmoid canal running from the apical pore to the anterior margin of the cingulum; (iv) three connected anterior intercalary plates; and (v) production of spherical cyst-like cells. The species is photosynthetic, containing many small greenish-brown chloroplasts. The tabulation of the species is Po, X, 4′, 3a, 7″, 6c, 5s?, 5′″, 2″″. Organic cyst-like cells were nearly spherical to subspherical, solitary, or aggregations linked by mucilaginous material; they are considered to be a stage in the life cycle of the species. Vulcanodinium rugosum is a new record in the study area. The ecology and the geographical distribution of the species are also discussed.

The purpose of this note is to communicate the diversity of endophytic fungi isolated from living leaves of Halodule wrightii and Thalassia testudinum , two ubiquitous seagrasses in the north-central Gulf of Mexico. Fungi were isolated from surface-sterilized leaf fragments of the two plants that had been inoculated onto seawater malt extract agar. Leaves of T. testudinum harbored slightly more endophyte taxa than those of H. wrightii. Trichocladium alopallonellum and 10 other fungal taxa are new records for H. wrightii . No distinct seasonal pattern in fungal filamentous growth was observed; however, our evidence suggests peak activity may take place in spring.