Search results for "Underwater"

Ticket to spawn: Combining economic and genetic data to evaluate the effect of climate and demographic structure on spawning distribution in Atlantic…

2019

Abstract Climate warming and harvesting affect the dynamics of species across the globe through a multitude of mechanisms, including distribution changes. In fish, migrations to and distribution on spawning grounds are likely influenced by both climate warming and harvesting. The Northeast Arctic (NEA) cod (Gadus morhua) performs seasonal migrations from its feeding grounds in the Barents Sea to spawning grounds along the Norwegian coast. The distribution of cod between the spawning grounds has historically changed at decadal scales, mainly due to variable use of the northern and southern margins of the spawning area. Based on historical landing records, two major hypotheses have been put f…

The killer shrimp, Dikerogammarus villosus, invading European Alpine lakes: a single main source but independent founder events with an overall loss …

2017

16 pages; International audience; 1. The effects of biological invasions are generally more detrimental in isolated ecosystems than in the interconnected ones and freshwater lakes appear to be particularly fragile. The Ponto-Caspian freshwater amphipod Dikerogammarus villosus (Pontogammaridae), also known as the killer shrimp, is a highly invasive species that can have significant ecological impacts on receiving ecosystems. It has colonised most of the European main inland waterbodies, including at least 12 lakes in the Alps – an area of high conservational priority and, at the same time, heavily affected by anthropogenic changes. Particularly, overland translocations of boats among tourist…

Fishing triggers trophic cascade in terms of variation, not abundance, in an allometric trophic network model

2022

Trophic cascade studies often rely on linear food chains instead of complex food webs and are typically measured as biomass averages, not as biomass variation. We study trophic cascades propagating across a complex food web including a measure of biomass variation in addition to biomass average. We examined whether different fishing strategies induce trophic cascades and whether the cascades differ from each other. We utilized an allometric trophic network (ATN) model to mechanistically study fishing-induced changes in food web dynamics. Different fishing strategies did not trigger traditional, reciprocal trophic cascades, as measured in biomass averages. Instead, fishing triggered a varia…

Adapted conservation measures are required to save the Iberian lynx in a changing climate

2013

The Iberian lynx ( Lynx pardinus ) has suffered severe population declines in the twentieth century and is now on the brink of extinction 1 . Climate change could further threaten the survival of the species 2 , but its forecast effects are being neglected in recovery plans 3,4 . Quantitative estimates of extinction risk under climate change have so far mostly relied on inferences from correlative projections of species’ habitat shifts 5 . Here we use ecological niche models coupled to metapopulation simulations with source–sink dynamics 6,7 to directly investi- gate the combined effects of climate change, prey availabil- ity and management intervention on the persistence of the Iberian lyn…

2018

The Atlantic surfclam (Spisula solidissima) is a commercially important species in North American waters, undergoing biological and ecological shifts. These are attributed, in part, to environmental modifications in its habitat and driven by climate change. Investigation of shell growth patterns, trace elements, and isotopic compositions require an examination of growth lines and increments preserved in biogenic carbonates. However, growth pattern analysis of S. solidissima is challenging due to multiple disturbance lines caused by environmental stress, erosion in umbonal shell regions, and constraints related to sample size and preparation techniques. The present study proposes an alternat…

Comparative analysis of abundance–occupancy relationships for species at risk at both broad taxonomic and spatial scales

2015

The abundance–occupancy relationship is one of the most well-examined relationships in ecology. At the species level, a positive association has been widely documented. However, until recently, research on the nature of this relationship at broad taxonomic and spatial scales has been limited. Here, we perform a comparative analysis of 12 taxonomic groups across a large spatial scale (Canada), using data on Canadian species at risk: amphibians, arthropods, birds, freshwater fishes, lichens, marine fishes, marine mammals, molluscs, mosses, reptiles, terrestrial mammals, and vascular plants. We find a significantly positive relationship in all taxonomic groups with the exception of freshwater…

Pervasive declines in monkfish (Lophius americanus) size structure throughout the northwest Atlantic

2020

Abstract Shifts in size structure have been documented for many commercially exploited marine fish stocks, thought to be attributed to size-selective harvesting practices coupled with changing oceanic conditions. Northwest Atlantic monkfish (Lophius americanus) is a commercially valued species in the United States that is commonly caught as bycatch in Canadian scallop and groundfish fisheries. This uniquely positioned stock is bisected by the Canadian–American jurisdictional boundary, with considerable differences in exploitation and management across its range. The status of this species was assessed two decades ago (2000) in the Maritimes region of Canada and more recently (2016) in the U…

Exploring individual and population eco-evolutionary feedbacks under the coupled effects of fishing and predation

2020

Intensive fishing that selects for large and old individuals can have pervasive effects on traits directly associated with the fecundity and survival of the target species. The observed reduction in fish body size can result in earlier sexual maturity at a smaller body size, leading to a lower individual reproductive output and population productivity in the long term. In addition, increased predation can induce similar responses in age and size at maturity due to the release of intraspecific competition and the lower population density. Thus, the combined impact of fisheries and predation is more difficult to predict due to their competition for fish, ultimately limiting and directing the …

The ormer (Haliotis tuberculata): A new, promising paleoclimatic tool

2015

International audience; This study aimed to investigate the environmental controls on the oxygen isotope composition of shells of the European abalone, Haliotis tuberculata. Seasonal delta O-18 profiles from the outer prismatic layer of four abalone shells, collected live in northwest Brittany (France) in 2002 and 2012, were compared to local temperatures and salinities. According to the findings herein, delta O-18 variations in abalone shells corresponded to seasonal variations, and thus, shell composition represented a reliable tool for aging and growth studies. Seawater temperatures estimated from the abalone collected in 2012 reflected the in situ measured temperatures, but the reconstr…

Identification of Two Carbonic Anhydrases in the Mantle of the European Abalone Haliotis tuberculata (Gastropoda, Haliotidae): Phylogenetic Implicati…

2012

Carbonic anhydrases (CAs) represent a diversified family of metalloenzymes that reversibly catalyze the hydration of carbon dioxide. They are involved in a wide range of functions, among which is the formation of CaCO(3) skeletons in metazoans. In the shell-forming mantle tissues of mollusks, the location of the CA catalytic activity is elusive and gives birth to contradicting views. In the present paper, using the European abalone Haliotis tuberculata, a key model gastropod in biomineralization studies, we identified and characterized two CAs (htCA1 and htCA2) that are specific of the shell-forming mantle tissue. We analyzed them in a phylogenetic context. Combining various approaches, inc…