Volume 54, Issue 4

The diversity of marine fungi is reviewed based on new data on their occurrence on various substrata, unexplored habitats especially in the tropics, undescribed species, endophytic and cryptic taxa. Various estimates have been proposed for the number of marine fungi and this depends on whether the taxa are obligate, facultative or marine derived by isolation from various substrata or from seawater by culture methods. The current number of obligate marine fungi (537 species) is a gross underestimate. So where can further species be found? In this review, several fungal groups are identified that have been poorly surveyed for marine representatives and therefore a potential source of more marine species; these are marine derived fungi isolated from soils, sand, and water, planktonic fungi, deep-sea fungi, unculturable fungi, and cryptic species or taxa with similar morphology. In accounting for these potential sources the number of marine fungi might be in excess of 10,000 taxa.

In subarctic regions, melting of glaciers creates stressful environmental conditions, such as reduced salinity and irradiance, in coastal benthic habitats such as kelp beds. Our goal was to determine whether these stressors differently affect kelp juveniles of Saccharina latissima originating from two environmentally distinct shores; one under oceanic and one under estuarine glacial influence. Laboratory tests assessed the effects of varying salinities and irradiances on growth and maximum quantum yield ( F v /F m ) of photosystem II of S. latissima . Overall, growth rates decreased with decreased salinity and irradiance. Growth rates of juveniles from the glacially influenced shore were significantly lower than those of the oceanic shore in most salinity and irradiances treatments. Juveniles from both shores grew negligibly at salinities below 13 and an irradiance of 5 μmol photons m -2 s -1 . At salinity 10, F v /F m was significantly reduced but F v /F m was not affected by decreased irradiance. S. latissima proved to be relatively tolerant to reduced salinities and irradiances but we detected limits to its resilience. Our results suggest that S. latissima populations exhibit phenotypic plasticity in their growth responses. This plasticity appears to be constrained within specific seasonal growth patterns in accordance with their environment of origin.

Levels of δ 15 N and molar C/N ratios were determined for the first time in 73 species of green, brown and red macroalgae at nine sites from differently polluted coastal areas of southern Vietnam in order to identify sources of dissolved inorganic nitrogen (DIN) used by seaweeds for their growth and development. The study sites were provisionally divided into two groups: open coast localities with presumably clear seawater and relatively isolated localities (bays and lagoons) polluted by waste from mariculture and sewage from cities and large villages. The algae collected at “pristine” and polluted sites had on average δ 15 N signatures of 3.3±0.9‰ and 8.6±1.1‰, respectively. Macroalgae from the west shore of Phu Quoc Island, O Lan Lagoon and Nha Trang Bay assimilated DIN from wastewater enriched with the heavy nitrogen isotope. Among the macroalgae investigated, bioindicators of DIN source were identified. These indicator algae belong mainly to the genera Ulva, Padina, Turbinaria, Gracilaria and Hydropuntia. Analysis of molar C/N ratios in algal tissue showed that thalli collected at “pristine” sites suffered limitation in nitrogen (on average, the C/N ratios=21.6±13.3). In most of the polluted areas, macroalgae were also N limited (on average, the C/N ratios=15.3±8.2).

The coastal bays of South Florida are located downstream of the Florida Everglades, where a comprehensive restoration plan will strongly impact the hydrology of the region. Submerged aquatic vegetation communities are common components of benthic habitats of Biscayne Bay, and will be directly affected by changes in water quality. This study explores community structure, spatio-temporal dynamics, and tissue nutrient content of macroalgae to detect and describe relationships with water quality. The macroalgal community responded to strong variability in salinity; three distinctive macroalgal assemblages were correlated with salinity as follows: (1) low-salinity, dominated by Chara hornemannii and a mix of filamentous algae; (2) brackish, dominated by Penicillus capitatus , Batophora oerstedii , and Acetabularia schenckii ; and (3) marine, dominated by Halimeda incrassata and Anadyomene stellata . Tissue-nutrient content was variable in space and time but tissues at all sites had high nitrogen and N:P values, demonstrating high nitrogen availability and phosphorus limitation in this region. This study clearly shows that distinct macroalgal assemblages are related to specific water quality conditions, and that macroalgal assemblages can be used as community-level indicators within an adaptive management framework to evaluate performance and restoration impacts in Biscayne Bay and other regions where both freshwater and nutrient inputs are modified by water management decisions.

Earlier morpho-anatomical work showed that a non-native Ulva species is widely distributed off the northwestern Iberian Peninsula (NWIP) since the early 1990s. However, insufficient sequence data provided at the time of the earlier study led to suggestions that more genetic evidence might be required to confirm this record. Here, we present this evidence in sequence data for the nuclear-encoded ITS1 and the plastid-encoded rbc L. We confirm the occurrence of an alien distromatic Ulva in several locations along the NWIP. Additionally, its presence in the Spanish Mediterranean (>1000 km away) is reported here for the first time. Species identification yielded notably coherent results between nuclear-encoded and plastid-encoded sequences, revealing that Spanish plants are conspecific with collections of Ulva pertusa and Ulva australis from a range of Pacific locations. The probable synonymy between U. australis and U. pertusa is consistent with their morphological similarity and suggests that U. australis is the correct name for the non-native green macroalga. ITS1 sequences reveal a common source for the various sites studied in the NWIP, possibly linked to shellfish transfers into the region. However, non-native populations in southern Spain must derive from an independent introduction event. This is the first time that molecular data have been used to demonstrate multiple introductions of U. australis to European waters.

A new species of the globally reported genus Lithothamnion is described. Lithothamnion carpoklonion grows in shallow-sheltered waters off La Parguera, Puerto Rico (Caribbean Sea) attached to mangrove prop roots in association with other encrusting algae. The new species has requisite generic characters in addition to developing dorsal protuberances formed by superimposition of uniporate (carpogonial) or multiporate conceptacles. It is suggested that by this unique mode of conceptacle production, enhanced fertilization and spore dispersal are achieved simultaneously as vegetative (perithallial) growth is reduced.

Primary production and biomass of Cymodocea nodosa in the Ghar El Melh lagoon (N-E of Tunisia) were measured from November 2006 to October 2007. Leaf growth was determined using the Zieman method and rhizome production was measured by marking and monitoring terminal rhizomes. The following parameters were measured: the number of new leaves per year (16 leaves year -1 ), the leaf Plastochrone Interval (23 days) and the life span of single leaves (from 2 to 7 months). Seasonality was apparent, with maximum growth in July, maximum leaf production (3.35 g dry weight m -2 d -1 ) in August, maximum leaf biomass (127.2 g dry weight m -2 ) and maximum of the shoot density (1437 shoots m -2 ) in September. Forty-five to 65% of all shoots were reproductive, with flowering density higher than generally observed in C. nodosa elsewhere in the Mediterranean. Environmental parameters (insolation, water temperature and salinity) had a strong seasonal influence on seagrass morphology and production; shoot density, biomass and leaf production were high in summer and low in winter.