LATE-HOLOCENE LAKE DIATOM-INFERRED PALAEOCLIMATE FROM CENTRAL TURKEY

Merged with duplicate record 10026.1/1308 on 27.03.2017 by CS (TIS)In the semi-arid environment of the Eastern Mediterranean, water can be a limiting resource and its availability is influenced by different climate factors. Knowledge of late Holocene water balance is limited for this region. Lake systems and organisms respond to environmental variability and can be used as a proxy for palaeoclimate. The aims of this research project were to reconstruct late Holocene palaeoclimate using diatom frustules preserved within crater lake sediments in central Turkey. Two lakes (Nar Golu and Kratergòl), located in the same climate region, were selected for this purpose. Modem lake samples and sediment cores collected between 1999-2006 were subsampled at high resolution for diatom analysis. Nar Golu provided an uninterrupted annually-laminated late Holocene sequence covering the last 1720 years. The varied lake sedimentation rate of Kratergòl was evident in sediment core coarse sandy sections and the sequence was thought to represent the mid-late 20th century. A diatom-salinity transfer function was employed using existing training sets from the European Diatom Database to infer past water balance. The reconstruction was calibrated with instrumental meteorological data. Reconstructed salinity was limited by poor analogue matching between the palaeo-diatom assemblage and the modem training set. This was partly associated with the presence of a previously undescribed diatom genus (newly named Clipeoparvus anatolìcus), which was highly abundant in the Nar modern environment and sediment record. Additional methods to extract palaeoenvironmental information from the diatom record were explored. This included calibrating diatom DCA axes with instrumental temperature in order to reconstruct palaeo-temperature, identifying mono-specific diatom bloom events in situ on core thin section shdes, calculating diatom biovolume, concentration, diversity and grouping species according to their habitat preferences. Comparison of the Nar and Kratergòl records highlighted the advantages of annually laminated lake sediments for palaeoenvironmental research and the limitations of sediment sequences from lakes with a varied sedimentation rate and poor chronological control. The primary meteorological control on the Nar diatom population was identified as summer temperature, via the link with lake water salinity. The Nar diatom sequence was compared with an oxygen isotope (palaeo-evaporation) and pollen record (human land use) from the same sediment cores and palaeoclimate reconstructions from other sites and regions. Nar diatoms and oxygen isotopes revealed that Cappadocia experienced high aridity prior to AD 540 and mono-specific diatom bloom events have become increasingly common during the most recent ~400 years. A diatom assemblage shift at AD 2001 also indicated a recent change in the system. Human land use evident in the pollen sequence may have influenced the diatom relationship with climatic variability in the later part of the record. The Kratergòl diatom record indicated environmental variability throughout the mid-late 20th century; however, interpretations were limited due to chronological discrepancies. The annually laminated Nar diatom record has provided a detailed account of palaeoenvironmental variability in central Anatolia throughout the late Holocene and contributes towards our understanding of Eastern Mediterranean palaeoclimate

PORIFERAL VISION

Sponges provide nourishment as well as a habitat for various aquatic organisms. Anatomically, sponges are made up of soft tissue with a silica based exoskeleton which serves both as support and protection for the underlying tissue. The exoskeleton persists after the tissue decomposes, and microscopic parts of the exoskeleton break away to form spicules. Oceanographic studies have shown that the density of the sponge spicules is a good indicator of the sponge population in an area. This measure can be used to study sponge population dynamics over time. The spicule density is measured by imaging spicules from samples of water extracted from the oceans using an instrument called FlowCAM, which separates and photographs individual small items in a sample. It has a high processing rate, but is inefficient at computationally analyzing large numbers of photographs. Computer vision technologies, particularly deep learning using Artificial Neural Networks, and Support Vector Machines have shown to be effective in handling large scale image classification problems and are the de-facto standard in image recognition problems. Typically, these models require a large amount of data to learn the underlying distribution in datasets effectively and avoid model overfitting, which is currently a challenge to procure a vast dataset of images. To mitigate this challenge and achieve the overarching purpose of developing a high- performance classifier, we demonstrate various geometrical image transformation techniques to enhance the size of the dataset. We also show initial experimental results for training Generative Adversarial Networks for artificial synthesis of spicule images. Finally, we develop a Convolutional Neural Network and compare its performance against a Support Vector Machine for classifying images of sponge spicules training both the models on the original set of images and the newly generated set of images and achieve a test accuracy of 95% with a CNN trained on the newly generated images

Couplerlib: a metadata-driven library for the integration of multiple models of higher and lower trophic level marine systems with inexact functional group matching

End-to-end modelling is a rapidly developing strategy for modelling in marine systems science and management. However, problems remain in the area of data matching and sub-model compatibility. A mechanism and novel interfacing system (Couplerlib) is presented whereby a physical–biogeochemical model (General Ocean Turbulence Model–European Regional Seas Ecosystem Model, GOTM–ERSEM) that predicts dynamics of the lower trophic level (LTL) organisms in marine ecosystems is coupled to a dynamic ecosystem model (Ecosim), which predicts food-web interactions among higher trophic level (HTL) organisms. Coupling is achieved by means of a bespoke interface, which handles the system incompatibilities between the models and a more generic Couplerlib library, which uses metadata descriptions in extensible mark-up language (XML) to marshal data between groups, paying attention to functional group mappings and compatibility of units between models. In addition, within Couplerlib, models can be coupled across networks by means of socket mechanisms. As a demonstration of this approach, a food-web model (Ecopath with Ecosim, EwE) and a physical–biogeochemical model (GOTM–ERSEM) representing the North Sea ecosystem were joined with Couplerlib. The output from GOTM–ERSEM varies between years, depending on oceanographic and meteorological conditions. Although inter-annual variability was clearly present, there was always the tendency for an annual cycle consisting of a peak of diatoms in spring, followed by (less nutritious) flagellates and dinoflagellates through the summer, resulting in an early summer peak in the mesozooplankton biomass. Pelagic productivity, predicted by the LTL model, was highly seasonal with little winter food for the higher trophic levels. The Ecosim model was originally based on the assumption of constant annual inputs of energy and, consequently, when coupled, pelagic species suffered population losses over the winter months. By contrast, benthic populations were more stable (although the benthic linkage modelled was purely at the detritus level, so this stability reflects the stability of the Ecosim model). The coupled model was used to examine long-term effects of environmental change, and showed the system to be nutrient limited and relatively unaffected by forecast climate change, especially in the benthos. The stability of an Ecosim formulation for large higher tropic level food webs is discussed and it is concluded that this kind of coupled model formulation is better for examining the effects of long-term environmental change than short-term perturbations

Proceedings Ocean Biodiversity Informatics: International Conference on Marine Biodiversity Data Management, Hamburg, Germany 29 November to 1 December, 2004

The International conference on Marine Biodiversity Data management ‘Ocean Biodiversity Informatics’ was held in Hamburg, Germany, from 29 November to 1 December 2004. Its objective was to offer a forum to marine biological data managers to discuss the state of the field, and to exchange ideas on how to further develop marine biological data systems. Many marine biologists are actively gathering knowledge, as they have been doing for a long time. What is new is that many of these scientists are willing to share their knowledge, including basic data, with others over the Internet. Our challenge now is to try and manage this trend, avoid confusing users with a multitude of contradicting sources of information, and make sure different data systems can be and are effectively integrated

SURFO Technical Report No. 17-01

The 2017 technical reports written by undergraduate students participating in the SURFO (Summer Undergraduate Research Fellowships in Oceanography) Program while at the University of Rhode Island for ten weeks

Diatomaceous Solar Cells

An experiment was conducted at the college of William and Mary to explore the ability of wild type diatoms to enhance the abilities of a Dye-Sensitized Solar Cell (DSSC). The goal was to see if the efficiency of a solar cell could be enhanced by the addition of wild-type diatoms in the active layer of the cell, and if there was any notable advantage to using diatoms where the frustule material had been altered. For this purpose, diatoms were cleaned using near-boiling baths of hydrogen peroxide and then coated in Titanium Dioxide using a peptide-mediated deposition [1]. Diatoms were tested under the TOF-SIMS and found to have an average atomic count Ti:Si ratio of 2.5 (range of .54—4.6) Ti/Si. DSSCs were then assembled: Two with no diatoms, two with uncoated diatoms, and two with coated diatoms. The cells without diatoms were found to have an efficiency of 1.78% ± .23%, the uncoated diatoms cells were found to have an efficiency of 1.11% ± .57%, and the coated diatoms cells were found to have an efficiency of .6311% ± .04%. These results do not show any indication that the diatoms have increased the efficiency of the solar cells at this time, nor is there any evidence that altering the frustrule material is advantageous for solar cell efficiency. These results may be due to problems in the consistency of our assembly process, and further research should focus on developing a method for depositing a reliable thickness for the TiO2 layer, and solving the saturation problem currently seen in our cells

Evolution of the Southern Kenya Rift from Miocene to present with a focus on the Magadi area

The Kenya (a.k.a., Gregory) Rift is a geologically active area located within the eastern branch of the larger East African Rift System (EARS). The study area is located in the southern Kenya Rift between 1° South and the Kenya-Tanzania border (covering approximately 1.5 square degrees, semi-centered on Lake Magadi) and is predominantly filled with extrusive igneous rocks (mostly basalts, phonolites and trachytes) of Miocene age or younger. Sediments are thin, less than 1.5Ma, and are confined to small grabens. The EARS can serve both as an analogue for ancient continental rifting and as a modern laboratory to observe the geologic processes responsible for rifting. This study demonstrates that vintage (as in older, quality maps published by the Kenya Geological Survey, that may be outdated based on newer findings) quarter-degree maps can be successfully combined with recently published data, and used to interpret satellite (mainly Landsat 7) images to produce versatile, updated digital maps. The study area has been remapped using this procedure and although it covers a large area, the mapping retains a quadrangle level of detail. Additionally, all geologic mapping elements (formations, faults, etc.) have been correlated across older map boundaries so that geologic units don\u27t end artificially at degree boundaries within the study area. These elements have also been saved as individual digital files to facilitate future analysis. A series of maps showing the evolution of the southern Kenya rift from the Miocene to the present was created by combining the updated geologic map with age dates for geologic formations and fault displacements. Over 200 age dates covering the entire length of the Kenya Rift have been compiled for this study, and 6 paleo-maps were constructed to demonstrate the evolution of the area, starting with the eruption of the Kishalduga and Lisudwa melanephelinites onto the metamorphic basement around 15Ma. These eruptions occurred before the initial rift faulting and were followed by a massive eruption of phonolites between 13-10 Ma that covered most of the Kenya dome. This was followed by a period of relative quiescence, until the initial faulting defined the western boundary of the rift around 7Ma. The resulting graben was asymmetrical until corresponding faults to the east developed around 3Ma. The rift valley was flooded by basalts and trachytes between 3Ma and 700ka, after which the volcanic activity slowed to a near halt. Since 700ka most of the deposition has been comprised of sediments, mainly from lakes occupying the various basins in the area. The main results of this study are, in addition to a detailed interpretation of the rift development, a new geologic map that correlates dozens of formations across old map boundaries and a compilation of over 300 age dates. Specific products include paleomaps, tables of fault timing and displacement, and volume estimates of volcanic formations. The study concludes with a generalization of the present environment at Magadi including discussions of lagoon chemistry, mantle gases in relation to the trona deposit, and biology of the hot springs. Several biologic samples were collected during the 2006 field season in an attempt to characterize the organisms that are commonly seen in the present Lake Magadi environment. Samples were selected to represent the different, distinctive forms that are found in the hotsprings. Each sample had it own distinctive growth habit, and analysis showed that each was formed by a different cyanobacterial. Actual algae was rare in the collected samples, and represented by a few scattered diatoms

How automated image analysis techniques help scientists in species identification and classification?

Identification of taxonomy at a specific level is time consuming and reliant upon expert ecologists. Hence the demand for automated species identification incre­ased over the last two decades. Automation of data classification is primarily focussed on images while incorporating and analysing image data has recently become easier due to developments in computational technology. Research ef­forts on identification of species include specimens’ image processing, extraction of identical features, followed by classifying them into correct categories. In this paper, we discuss recent automated species identification systems, mainly for categorising and evaluating their methods. We reviewed and compared different methods in step by step scheme of automated identification and classification systems of species images. The selection of methods is influenced by many variables such as level of classification, number of training data and complexity of images. The aim of writing this paper is to provide researchers and scientists an extensive background study on work related to automated species identification, focusing on pattern recognition techniques in building such systems for biodiversity studies. (Folia Morphol 2018; 77, 2: 179–193

Flandrian relative sea-level changes in the Cree estuary region, south west Scotland

The northern shoreline of the Solway Firth (SW Scotland) is well established as being a region containing a wealth of evidence for changing sea-levelssince the end of the last glaciation circa 10,000 years ago