The Boulder Patch (North Alaska, Beaufort Sea) and its Benthic Algal Flora

We describe the benthic algal flora within the Boulder Patch, a unique and relatively isolated assemblage of cobbles and boulders in the Alaskan Beaufort Sea, on the basis of a compilation of opportunistic in situ collections made from 1977 to 2006. The Boulder Patch is a shallow (4–7 m) High Arctic kelp community containing 78 benthic algal species, all of which represent approximately one-half of the pan-Arctic benthic flora (140 species) including one recognized cyanophyte (Calothrix scopulorum), one dinophyte (Rufusiella foslieana), 26 green algae, 25 brown algae, and 25 red algal species. Two brown algae are Arctic endemics, and 41 of the 78 Boulder Patch species also occur in the North Pacific Ocean and southeast Alaska. Both endemic species occur widely in the Arctic Ocean and extend into the northern North Atlantic Ocean. All 78 Boulder Patch species occur widely in the northeast Atlantic Ocean. No recognizable endemic species from the boreal/subarctic Pacific and Atlantic Oceans are present in the Boulder Patch. Only four species, two of which are closely related and host-specific, show a poleward shift from the boreal to the High Arctic environment. The algal composition of the Boulder Patch and characterization of these algal communities represent an invaluable baseline in which to assess future change in an Arctic system that is undergoing rapid warming. Our baseline analysis of the benthic flora of the Boulder Patch reveals a habitat characterized by an unexpected high diversity and unique phytogeography for a relatively isolated benthic algal assemblage of the north polar ocean.Nous décrivons la flore algale benthique faisant partie de la Boulder Patch, un assemblage unique et relativement isolé de galets et de rochers de la mer de Beaufort alaskienne. Cette description s’appuie sur la compilation de collections opportunistes recueillies sur place de 1977 à 2006. La Boulder Patch est un varech peu profond (de 4 à 7 m) de l’Extrême-Arctique qui contient 78 espèces d’algues benthiques, représentant environ la moitié de la flore benthique panarctique (140 espèces), dont une cyanophyte reconnue (Calothrix scopulorum), une dinophyte (Rufusiella foslieana), 26 algues vertes, 25 algues brunes et 25 espèces algales rouges. Deux algues brunes sont endémiques à l’Arctique, et 41 des 78 espèces de la Boulder Patch se retrouvent également dans l’océan Pacifique Nord et dans le sud-est de l’Alaska. Les deux espèces endémiques se trouvent souvent dans l’océan Arctique et s’étendent jusque dans le nord de l’Atlantique Nord. Les 78 espèces de la Boulder Patch sont fortement répandues dans le nord-est de l’océan Atlantique. Aucune espèce endémique reconnaissable des segments boréaux et subarctiques des océans Pacifique et Atlantique ne sont présents dans la Boulder Patch. Seulement quatre espèces, dont deux sont très proches et spécifiques à un hôte, montrent un déplacement vers le pôle, du milieu boréal au milieu de l’Extrême-Arctique. La composition algale de la Boulder Patch et la caractérisation de ces communautés algales représentent une précieuse base de référence permettant d’évaluer les changements à venir dans un système arctique où le réchauffement se produit rapidement. L’analyse de notre base de référence de la flore benthique de la Boulder Patch révèle un habitat caractérisé par une grande diversité inattendue et par une phytogéographie unique pour un assemblage algal benthique relativement isolé de l’océan polaire nordique

Seasonal and Annual Dynamics In Seagrass Beds of the Grand Bay National Estuarine Research Reserve, Mississippi

Along the mainland coastline of eastern Mississippi Sound, the seagrass species Ruppia maritima (Wigeongrass) and Halodule wrightii (Shoalgrass) co-occur in persistent and sometimes extensive beds within Grand Bay. This paper presents seasonal and annual changes in those Ruppia-Halodule beds that are part of the Grand Bay National Estuarine Research Reserve in western Grand Bay using 2005–2011 transect survey data of percent cover and 2009–2013 biomass sampling data. The seagrass beds exhibited significant interannual variation in areal coverage and seasonal variations in biomass, with peak total aboveground biomass (up to 140 g dry wt/m²) in July and August. Intact R. maritima and H. wrightii seeds were found in the sediment, with densities as high as 4160 seeds/m². The Ruppia-Halodule beds did not show any shortterm declines in their growth or abundance following 2005 Hurricanes Katrina and Rita nor the 2010 Deepwater Horizon oil spill

Seasonal Production and Biomass of the Seagrass, Halodule wrightii Aschers. (Shoal Grass), in a Subtropical Texas Lagoon

A study of Halodule wrightii in a shallow subtropical Texas lagoon was performed to obtain seasonal data on its physiological ecology. Leaf production and biomass dynamics of H. wrightii were intensively monitored along with the underwater light environment at a 1.2-m depth study site over a 21-month period from June 1995 to February 1997. The annual photosynthetically active radiation (PAR) flux of 6,764 mol m−2 year−1 was more than twice as high as 2,400 mol m−2 year−1, the minimum annual PAR required for maintenance of growth. As light intensity declined, blade chlorophyll a/b ratios increased suggesting that the plants were photo-adapting. Seasonal trends were evident in shoot growth and biomass. Compared to other Halodule populations in Texas, H. wrightii in LLM displayed slow growth and low biomass, high leaf tissue N content, and low C/N ratio but high N/P ratio of 38 suggesting that the plants were phosphorus-limited