Contrasting Life Traits of Sympatric Calanus glacialis and C. finmarchicus in a Warming Arctic Revealed by a Year-Round Study in Isfjorden, Svalbard

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Postglacial expansion of the arctic keystone copepod calanus glacialis

Calanus glacialis, a major contributor to zooplankton biomass in the Arctic shelf seas, is a key link between primary production and higher trophic levels that may be sensitive to climate warming. The aim of this study was to explore genetic variation in contemporary populations of this species to infer possible changes during the Quaternary period, and to assess its population structure in both space and time. Calanus glacialis was sampled in the fjords of Spitsbergen (Hornsund and Kongsfjorden) in 2003, 2004, 2006, 2009 and 2012. The sequence of a mitochondrial marker, belonging to the ND5 gene, selected for the study was 1249 base pairs long and distinguished 75 unique haplotypes among 140 individuals that formed three main clades. There was no detectable pattern in the distribution of haplotypes by geographic distance or over time. Interestingly, a Bayesian skyline plot suggested that a 1000-fold increase in population size occurred approximately 10,000 years before present, suggesting a species expansion after the Last Glacial Maximum.GAME from the National Science Centre, the Polish Ministry of Science and Higher Education Iuventus Plus [IP2014 050573]; FCT-PT [CCMAR/Multi/04326/2013]; [2011/03/B/NZ8/02876

Changes in fecal pellet characteristics with depth as indicators of zooplankton repackaging of particles in the mesopelagic zone of the subtropical and subarctic North Pacific Ocean

Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 55 (2008): 1636-1647, doi:10.1016/j.dsr2.2008.04.019.We investigated how fecal pellet characteristics change with depth in order to quantify the extent of particle repackaging by mesopelagic zooplankton in two contrasting open-ocean systems. Material from neutrally buoyant sediment traps deployed in the summer of 2004 and 2005 at 150, 300, and 500 m was analyzed from both a mesotrophic (Japanese time-series station K2) and an oligotrophic (Hawaii Ocean Time series-HOT station ALOHA) environment in the Pacific Ocean as part of the VERtical Transport In the Global Ocean (VERTIGO) project. We quantified changes in the flux, size, shape, and color of particles recognizable as zooplankton fecal pellets to determine how these parameters varied with depth and location. Flux of K2 fecal pellet particulate organic carbon (POC) at 150 and 300 m was 4-5 times higher than at ALOHA, and at all depths, fecal pellets were 2-5 times larger at K2, reflective of the disparate zooplankton community structure at the two sites. At K2, the proportion of POC flux that consisted of fecal pellets generally decreased with depth from 20% at 150 m to 5% at 500 m, whereas at ALOHA this proportion increased with depth (and was more variable) from 14% to 35%. This difference in the fecal fraction of POC with increasing depth is hypothesized to be due to differences in the extent of zooplankton-mediated fragmentation (coprohexy) and in zooplankton community structure between the two locations. Both regions provided indications of sinking particle repackaging and zooplankton carnivory in the mesopelagic. At ALOHA this was reflected in a significant increase in the mean flux of larvacean fecal pellets from 150 to 500 m of 3 to 46 μg C m-2 d-1, respectively, and at K2 a large peak in larvacean mean pellet flux at 300 m of 3.1 mg C m-2 d-1. Peaks in red pellets produced by carnivores occurred at 300 m at K2, and a variety of other fecal pellet classes showed significant changes in their distribution with depth. There was also evidence of substantially higher pellet fragmentation at K2 with nearly double the ratio of broken:intact pellets at 150 and 300 m (mean of 67% and 64%, respectively ) than at ALOHA where the proportion of broken pellets remained constant with depth (mean 35%). Variations in zooplankton size and community structure within the mesopelagic zone can thus differentially alter the transfer efficiency of sinking POC.This study was supported by grants from the U.S. National Science Foundation NSF OCE-0324402 (Biological Oceanography) to D.K.S and OCE-0301139 (Chemical Oceanography) to K.O.B

Biogeography of the oceans.

This chapter summarizes global patterns and mechanisms of both ecological and historical crustacean biogeography resulting in the contemporary species distributions described over the past decades. In the pelagic realm, hydrographic features such as ocean currents, physical depth profiles, and latitudinal temperature gradients are major structuring elements, as well as selection pressure exerted by the environment and species interactions, which have resulted in speciation over evolutionary time. Benthic crustacean distributions are additionally constrained longitudinally by continental barriers and submarine features such as ridges and seamounts. The main biogeographic patterns of both benthic and pelagic crustaceans are described for all ocean basins and the polar regions, of which the Indian Ocean is the least well studied. The Copepoda and Decapoda are generally represented with the highest number of described species, followed by Amphipoda and Isopoda. Life cycles with pelagic larvae (e.g., decapods and stomatopods) increase dispersal and enable wide distributions, while a lack of dispersive larvae promotes endemism in benthic forms (e.g., amphipods). Restricted regions with high species richness and endemism, such as the “coral triangle” (the Indo-Australian Archipelago), the Red Sea, and the Mediterranean, represent important biodiversity hotspots. Endemics are also suitable markers for past earth history events. Only a few studies cover the biogeography of crustacean taxa in all of the world’s oceans, but a few exceptions exist for decapods, amphipods, and isopods. Although the world’s oceans have been reasonably well studied for crustacean distribution and diversity, species complexes and cryptic species lacking morphological diagnostic features leave us with a large number of unconsolidated taxa. Emerging molecular tools may be able to assist with refinement of nomenclature and hence increase the resolution of crustacean biogeography in the future