Spektralni profili vrsta Caulerpa racemosa var. cylindracea i Caulerpa taxifolia u Jadranskom moru

The invasive algae in the Mediterranean Caulerpa taxifolia and Caulerpa racemosa var. cylind-racea have gained much interest in the Adriatic Sea due to their fast spread and negative impacts on native seaweed species. Lack of accurate mapping and its overall high costs represent some of the major difficulties for successful detection and subsequent environmental management. Remote sensing techniques could provide a quicker, more accurate and more cost efficient approach to mapping these invasive species. In order to allow for classification of remotely sensed data, we have collected and analyzed hyperspectral reflectance profiles of both invasive Caulerpa species in the Adriatic and the native Caulerpa cf. laetevirens species from the southeastern Atlantic coast of the United States. We have measured distinctive spectral features for spectroscopically distinguishing between these species, which is particularly interesting in the areas where these native and invasive species coex-ist. The initial results suggest that it might be possible to distinguish between the species based on their spectral reflectance profile. These results would have to be verified with samples taken from more populations in different phenological phases of the seaweed growth and other environmental conditions.Invazivne alge u Sredozemnom moru, Caulerpa taxifolia i Caulerpa racemosa var. cylindracea, su izazvale mnogo interesa zbog svojeg brzog širenja i negativnih utjecaja na nativne vrste morskog raslinja. Jednu od najvećih poteškoća za upravljanje ovim invazivnim vrstama predstavlja nedostatak preciznih karata rasprostranjenosti, odnosno visoka cijena izrade ovakvih karata. Tehnike daljinske detekcije mogu pružiti brži, učinkovitiji i ekonomičniji način kartiranja ovih vrsta. Kako bi omogućili klasifikaciju podataka prikupljenih daljinskom detekcijom, sakupljeni su i analizirani hiperspektralni profili obje invazivne vrste kaulerpe u Jadranu i nativne vrste Caulerpa cf. laetevirens na jugoistočnoj atlantskoj obali Sjedinjenih Američkih Država. Izmjerena su i utvrđena karakteristična spektralna obilježja ovih vrsta u cilju omogućavanja njihovog spektroskopskog razlikovanja, što je naročito interesantno u onim područjima gdje koegzistiraju nativne i invazivne vrste kaulerpe. Inicijalni rezultati pokazuju da je moguće razlikovati vrste između ovih tipova na osnovu njihovog spektralnog profila. Ovi rezultati još trebaju biti potvrđeni na uzorcima iz više populacija u različitim fenološkim fazama i u različitim uvjetima okoliša

Effects of invasive species on vulnerability of the Adriatic sea

Velike klimatske oscilacije te geološka aktivnost Zemlje odredila je jedinstven položaj i pružanje Jadranskog mora te njegovu bioraznolikost. Prokopavanjem Sueskog kanala 1869. godine Sredozemno more nanovo se povezalo sa Crvenim morem, što je omogućilo migraciju lesepsijskim organizmima te naseljavanje područja koja im nisu bila prirodno stanište i ugrožavanje autohtonih vrsta i ekosistema. Osim Sueskim kanalom invazivne vrste su u Jadran dospjele direktno ili indirektno, no često djelovanjem čovjeka. Zbog sve veće ugroženosti Jadranskog mora sve više istraživanja i studija se vodi u kojima glavnu riječ imaju invazivne vrste te njihov utjecaj. Prevencija je najbolja metoda kontrole invazivnih vrsta. Dobar monitoring prostora te brza reakcija na moguću pojavnost invadora najbolji su način očuvanja autohtonih vrsta od penetriranja invazivnih vrsta.Great climatic oscillations and geological activity of the Earth has set a unique position of the Adriatic Sea and its biodiversity. Digging of the Suez Canal in 1869, the Mediterranean Sea was re-linked with the Red Sea which allowed the migration of the Lessepsian organisms and settlement on areas that they don’t naturally populate. Also, their presence threatens native species and ecosystems. Except through the Suez Canal, invasive species entered the Adriatic Sea directly or indirectly, but often due to the action of man. Due to the increasing vulnerability of the Adriatic Sea more research and study is conducted in which main role have invasive species and their impact. Prevention is the best method of controlling invasive species. Good monitoring of the space and rapid response to the possible occurrence of the invasive species are the best way to preserveindigenous species of penetration of invasive species

Seasonality and nutrient-uptake capacity of Sargassum spp. in Western Australia

The eight-band high resolution multispectral WorldView-2 satellite imagery demonstrated potential for mapping and monitoring Sargassum spp. beds and other associated coastal marine habitats around Rottnest Island and Point Peron. Sargassum spp. in Western Australian coast showed seasonal changes in canopy cover and mean thallus length which are also significantly influenced by the nutrient concentrations. This study documented the life cycle of Sargassum spinuligerum and successfully cultivated the species for the first time in Western Australia

The environmental change in coastal ecosystems during the Late Holocene as recorded in seagrass sedimentary archives

[eng] Coastal ecosystems, especially the vegetated areas, are among the most threatened ecosystems in the world, undergoing a fast and constant decline. Their losses are of serious concern due to their elevated production, providing many ecosystem services essential to the well-being of our societies. Behind the regressive trends of the coastal ecosystems, there is a plethora of adverse human pressures, going from local and regional impacts, including anthropogenic activities in and outside the coastal regions, to large-scale drivers of change, such as the global warming. Nevertheless, there is a critical lack of long-term information about the vegetated coastal ecosystems, information that can provide baseline ecological data of their natural dynamics and vulnerability. Seagrasses are marine plants, engineering species that form underwater meadows, which, among many other services, provide essential habitat for many other organisms. Seagrasses meadows are experiencing a widespread decline since the early 20th century. This regression is accelerated for the Mediterranean endemic seagrass species Posidonia oceanica. Long-term studies are of particular interest in P. oceanica meadows because this species is a large-slow growing and long-lived seagrass, which substantial changes and responses manifest over time scales of decades to centuries. A deeper understanding of seagrass long-term dynamics can help managers to apply meadow-specific actions and act at the appropriate temporal scales. The discipline of paleoecology allows the study of long-term ecosystem dynamics on time scales of centuries to millennia, and it can be used in seagrass meadows thanks to the organic deposits accumulated below P. oceanica meadows. Paleoreconstructions using seagrass deposits are still scarce and have mainly focused on allogenic (externally controlled) processes. In this dissertation, a paleoecological approach at a regional spatial-scale was used to explore the long-term dynamics of the autogenic and biotic ecological components of Mediterranean seagrass meadows, mainly P. oceanica meadows. Initially, we investigated the usefulness of several biogeochemical proxies and a technique (FTIR-ATR spectroscopy) so far unexplored in seagrass deposits, as well as which were the main biogeochemical processes recorded by them. We described the long-term dynamics of the seagrass ecosystem, the main drivers of change, and their relative importance. The results indicated that seagrass long-term dynamics are oscillating. Even though most meadows showed regressive trends during the last 150 years, seagrass trends varied spatially, with the main spatial differences occurring at the inter-regional level. Differences in long-term dynamics between local sites seemed mostly dependent on the environmental background of each site, which also affected seagrass long- term resilience. The major factors responsible for long-term variability of seagrass ecosystem dynamics were multiple and at both, local and large spatial scales. However, the balance between the contribution of local and large-scale drivers varied spatially. The influence of climate seemed especially crucial in meadows surrounded by more turbid waters, under the influence of higher fluvial discharges. These meadows showed lower long-term ecosystemic resilience. In summary, this research showed that seagrass long-term dynamics can be studied through their paleoecological record, providing a valuable frame of reference for evaluating the magnitude of current changes and consequences of combined diverse impacts on these marine ecosystems. The results of this thesis indicated that despite some spatial variability of the long-term dynamics, the major changes occurred over the last century, predominating trends of seagrass decline or community compositional changes. Moreover, our results point to a more acute negative impact of present climate change in meadows where light availability is compromised due to local factors. The overall spatial variability regarding seagrass long-term dynamics highlights the need for meadow-specific local management with background information, information that can be obtained from paleoecological studies.[spa] Los ecosistemas costeros, especialmente aquellos dominados por macrófitos sumergidos o semi-sumergidos, se encuentran entre los ecosistemas más amenazados del mundo, sufriendo un rápido y constante declive. Sus pérdidas son motivo de grave preocupación debido a su elevada producción, y a que proporcionan muchos servicios ecosistémicos esenciales para el bienestar de nuestras sociedades. Detrás de las tendencias regresivas de los ecosistemas costeros, se encuentra una plétora de presiones humanas adversas, que van desde impactos locales y regionales, incluidas actividades antropogénicas dentro y fuera de las regiones costeras, hasta agentes de cambio a gran escala, como el calentamiento global. Sin embargo, existe una falta crítica sobre el cambio a largo plazo de los ecosistemas costeros vegetados, información que puede proporcionar datos ecológicos de referencia sobre sus dinámicas naturales y vulnerabilidad. Las fanerógamas marinas son plantas superiores creadoras de estructuras tridimensionales complejas que, entre otros muchos servicios, dan lugar a un hábitat de elevada biodiversidad. Estos macrófitos están experimentando un declive generalizado desde principios del siglo XX, regresión especialmente acelerada para la especie endémica mediterránea, Posidonia oceanica. Los estudios a largo plazo son de particular interés en las praderas de P. oceánica, pues al ser una planta marina de gran tamaño, de crecimiento lento y de vida larga, sus cambios y respuestas sustanciales se manifiestan en escalas de tiempo de décadas a siglos. Una comprensión más profunda de la dinámica a largo plazo de las fanerógamas marinas puede ayudar a los gestores a aplicar acciones específicas y actuar en las escalas temporales adecuadas. La disciplina de la paleoecología permite el estudio de la dinámica de los ecosistemas a largo plazo en escalas de tiempo de siglos a milenios, y se puede aplicar en praderas de fanerógamas de P. oceanica gracias a los depósitos orgánicos acumulados bajo ellas. Las reconstrucciones paleoecológicas que usan suelos de praderas marinas aún son escasas y las que hay se han centrado principalmente en procesos alogénicos del ecosistema (controlados externamente). En esta tesis se ha hecho uso de reconstrucciones paleoecológicas en praderas de fanerógamas mediterráneas, principalmente de P. oceánica, a una escala espacial regional con el objetivo de explorar la dinámica a largo plazo de los componentes ecológicos autogénicos y bióticos. Inicialmente, se investigó la utilidad de varios proxies (indicadores) biogeoquímicos y de una técnica (espectroscopía FTIR-ATR) hasta ahora inexplorados en depósitos de praderas marinas, así como cuáles eran los principales procesos biogeoquímicos registrados por estos depósitos. Los resultados obtenidos permitieron describir la dinámica a largo plazo de las praderas marinas, así como sus principales impulsores del cambio a largo plazo y su importancia relativa. Se observó que la dinámica a largo plazo es oscilante, y que la mayoría de las praderas mostraban tendencias regresivas durante los últimos 150 años. Sin embargo, estas tendencias de declive variaban espacialmente, ocurriendo las principales diferencias a escala interregional. Las diferencias en la dinámica a largo plazo entre localidades parecían depender principalmente del contexto ambiental de cada sitio, lo que también afectaba a la resiliencia a largo plazo de las praderas. Los resultados revelan que los principales factores responsables de la variabilidad a largo plazo son múltiples, incluyendo factores de carácter local pero también regional y global. Sin embargo, la contribución relativa entre los factores de influencia local y de gran escala varia espacialmente. La influencia del clima parece especialmente crucial en praderas creciendo en aguas más turbias, bajo la influencia de descargas fluviales más abundantes. Estas praderas mostraron una menor resiliencia ecosistémica a largo plazo. En resumen, esta investigación ha demostrado que las dinámicas a largo plazo de las fanerógamas marinas se pueden estudiar a través de su registro paleoecológico, proporcionando un valioso marco de referencia para evaluar la magnitud de cambios actuales y las consecuencias de diversos impactos combinados en estos ecosistemas marinos. Los resultados de esta tesis revelan que, a pesar de cierta variabilidad espacial de las dinámicas a largo plazo, los cambios más importantes han ocurrido durante el último siglo, predominando las tendencias de declive de la fanerógama o cambios en la composición de las comunidades que alberga. Además, nuestros resultados apuntan a un impacto negativo más agudo del actual cambio climático en aquellas praderas donde la disponibilidad de luz se ve comprometida debido a causas locales. La variabilidad espacial general de las dinámicas a largo plazo de las praderas marinas destaca la necesidad de una gestión local específica a cada pradera, con información previa contextual, información que se puede obtener a partir de estudios paleoecológicos