scholarly journals Temperature-mediated outbreak dynamics of the invasive bryozoan Membranipora membranacea in Nova Scotian kelp beds

2009 ◽  
Vol 390 ◽  
pp. 1-13 ◽  
Author(s):  
RE Scheibling ◽  
P Gagnon
Keyword(s):  
Membranipora Membranacea ◽  
Kelp Beds ◽  
Invasive Bryozoan ◽  
Nova Scotian

Invasive bryozoan alters interaction between a native grazer and its algal food

2013 ◽  
Vol 93 (5) ◽  
pp. 1393-1400 ◽  
Author(s):  
John M. O'Brien ◽  
Kira A. Krumhansl ◽  
Robert E. Scheibling
Keyword(s):  
Choice Experiment ◽  
Large Scale ◽  
Atlantic Coast ◽  
Grazing Rate ◽  
Choice Experiments ◽  
Saccharina Latissima ◽  
Membranipora Membranacea ◽  
Kelp Beds ◽  
Lacuna Vincta ◽  
Invasive Bryozoan

The epiphytic bryozoan Membranipora membranacea encrusts the surface of kelp blades, causing recurrent large-scale defoliation events in kelp beds off the Atlantic coast of Nova Scotia, Canada. The gastropod Lacuna vincta grazes kelp, creating perforations that weaken blade tissues and increase the fragmentation rate. We assess the interaction between M. membranacea and L. vincta by measuring the grazing rate of snails on bryozoan-encrusted and non-encrusted kelp (Saccharina latissima) in no-choice and choice experiments in the laboratory conducted in November and December 2010. There was no effect of diet on grazing rate in no-choice experiments. In choice experiments, however, L. vincta grazed significantly more non-encrusted than encrusted kelp (7.1 versus 1.1 mg snail−1 d−1), and grazing rate of non-encrusted kelp was almost twice that in the no-choice experiment (3.8 mg snail−1 d−1), indicating that snails may avoid colonies of M. membranacea on partially encrusted kelp blades. We found no effect of diet on growth, reproduction and survival of snails maintained for four weeks on encrusted or non-encrusted kelp. By concentrating grazing damage on non-encrusted areas of blades, L. vincta may act synergistically with M. membranacea to increase the likelihood of blade breakage and canopy loss. This indirect effect of the invasive bryozoan could augment its direct effect on the standing biomass of native kelp beds and detrital export to adjacent communities.

Diversity, Patterns of Adaptation, and Stability of Nova Scotian Kelp Beds

1988 ◽  
Vol 58 (2) ◽  
pp. 129-154 ◽  
Author(s):  
Craig R. Johnson ◽  
Kenneth H. Mann
Keyword(s):  
Diversity Patterns ◽  
Kelp Beds ◽  
Nova Scotian

Disease as a control of sea urchin populations in Nova Scotian kelp beds

2014 ◽  
Vol 500 ◽  
pp. 149-158 ◽  
Author(s):  
CJ Feehan ◽  
RE Scheibling
Keyword(s):  
Sea Urchin ◽  
Kelp Beds ◽  
Nova Scotian

Diversity, Patterns of Adaptation, and Stability of Nova Scotian Kelp Beds

1988 ◽  
Vol 58 (3) ◽  
pp. 227-227 ◽  
Author(s):  
Craig R. Johnson ◽  
Kenneth R. Mann
Keyword(s):  
Diversity Patterns ◽  
Kelp Beds ◽  
Nova Scotian

Destructive grazing, epiphytism, and disease: the dynamics of sea urchin - kelp interactions in Nova Scotia

1999 ◽  
Vol 56 (12) ◽  
pp. 2300-2314 ◽  
Author(s):  
Robert E Scheibling ◽  
Allan W Hennigar ◽  
Toby Balch
Keyword(s):  
Nova Scotia ◽  
Sea Urchin ◽  
Canopy Cover ◽  
Strongylocentrotus Droebachiensis ◽  
Exposed Site ◽  
Membranipora Membranacea ◽  
Kelp Beds ◽  
Sheltered Site ◽  
Kelp Canopy ◽  
Over Time

We measured the rate of advance of urchin (Strongylocentrotus droebachiensis) feeding aggregations (fronts) as they destructively grazed kelp beds (Laminaria longicruris) at both a wave-exposed site and a sheltered site in Nova Scotia over 3.5 years. The grazing fronts were composed of high densities of large adults (up to 98 and 70 per 0.25 m2 at the exposed and sheltered sites, respectively). Urchins in the recently formed barrens, or in adjacent kelp beds, occurred at much lower densities and consisted mainly of juveniles. The fronts moved onshore into shallower water at each site, but their rate of advance varied markedly between sites and over time at each site, ranging from 0 to 4 m·month-1. The rate of advance of a front was related to the biomass of urchins; fronts did not advance below a threshold biomass of ~2 kg·m-2. Infestations of kelp by an epiphytic bryozoan (Membranipora membranacea) caused marked reductions in kelp canopy cover and biomass during winter, but the canopy regenerated through recruitment of juvenile sporophytes in spring. A localized outbreak of disease decimated S. droebachiensis at the exposed site in 1993, which enabled kelp to recolonize the barrens. Surviving urchins gradually reaggregated and resumed destructive grazing after ~1.5 years. A recurrence of disease in 1995 eliminated urchins at both sites and terminated the transition from kelp beds to barrens on a coastal scale. Our findings have important implications for the management of the urchin fishery, which targets grazing fronts for harvesting.

scholarly journals Relative importance of organic- and iron-based colloids in six Nova Scotian lakes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lindsay E. Anderson ◽  
Benjamin F. Trueman ◽  
Dewey W. Dunnington ◽  
Graham A. Gagnon
Keyword(s):  
Process Design ◽  
Drinking Water Treatment ◽  
Remote Communities ◽  
Colloidal Iron ◽  
Quality Outcomes ◽  
Iron Aluminum ◽  
Icp Ms ◽  
Fraction Absorbed ◽  
Nova Scotian ◽  
Continue Monitoring

AbstractDissolved organic matter (DOM) concentrations have been increasing in parts of the northern hemisphere for several decades. This process—brownification—often accompanies increasing iron and aluminum, but the metal–DOM interactions these concurrent trends imply are poorly described. Here we used field-flow fractionation with UV and ICP-MS detection to measure the size distribution of colloidal iron, aluminum, manganese, copper, uranium, and chromophoric DOM in six lakes over six months. Five of these lakes have browned to some degree in the past three decades, with linear increases in organic carbon and color ranging from 0.01 to 0.13 mg C L−1 yr−1 and 0.13–1.94 PtCo yr−1. Browning trends were more pronounced and colloids more abundant in lakes with wetlands in their catchments. Iron and aluminum were present in two primary fractions, sized nominally at 1 and 1000 kDa. The 1 kDa fraction included the primary DOM signal, while the 1000 kDa fraction absorbed minimally at 254 nm and likely represents iron-rich (oxyhydr)oxides. Colloidal manganese was sized at 1000+ kDa, whereas colloidal copper and uranium occurred primarily at 1 kDa. These associations fit with a pattern of increasing DOC, iron, aluminum, and color in the region’s lakes. They represent a significant challenge for drinking water treatment systems, especially those in remote communities. Given that browning trends are expected to continue, monitoring plans would better inform treatment process design and operation by characterizing DOM and iron-rich, primarily inorganic colloids that contribute to adverse water quality outcomes.

Alternative environment activities on both sides of the Atlantic: A Canada-Ireland consideration and comparison

2021 ◽  
pp. 1356336X2098588
Author(s):  
Daniel B Robinson ◽  
Nathan Hall ◽  
José da Costa ◽  
Brent Bradford
Keyword(s):  
Nova Scotia ◽  
Administrative Support ◽  
Vigorous Physical Activity ◽  
Comparative Investigation ◽  
Data Sets ◽  
Online Questionnaire ◽  
Traditional Sports ◽  
Development Participation ◽  
Ice Water ◽  
Nova Scotian

Due to the overemphasis of traditional sports at the expense of other movement domains in physical education (PE) programmes, there is a need to consider what factors might enable or limit PE teachers’ incorporation of some of these other domains that can support student learning. The focus of this article is on one such marginalized domain – alternative environment activities (AEAs). AEAs can afford students a breadth of opportunities for moderate-to-vigorous physical activity in different environments (i.e. land, snow and ice, water, air) and improve environmental awareness and stewardship. This article reports on a comparative investigation of Nova Scotian (Canadian) and Irish PE teachers’ incorporation of AEAs in their PE programmes. To understand what similarities or differences might exist with respect to these PE teachers’ incorporation of AEAs, along with existing enablers and barriers, a self-selected sample of current PE teachers (Nova Scotia = 53; Ireland = 64) completed a 22-item online questionnaire. Descriptive and inferential statistical analyses were employed to conduct comparisons among the two data sets. PE teachers’ understandings of curricular requirements for AEAs were found to be an issue in both Nova Scotia and Ireland. Reported significant differences include: AEA-related professional development participation; most important factors for deciding not to include AEAs; and feelings of school administrative support towards AEA incorporation. Findings also suggest that various issues may be hindering incorporation of AEAs in PE programmes, and that some of these issues do differ based on where the PE programme is situated.

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