My Final Paper Submitted for GGR305 - Biogeography.
MIKAEL SYED
Department of Geography, Geomatics and Environment, University of Toronto
GGR305 - Biogeography
Dr. Tenley Conway
March 29th 2024
Case Study - GGR305.pdf
Abstract
California coastline’s marine ecosystems have undergone several changes from the last period of Pleistocene to date due to notable and considerable alterations in climate as well as geomorphology; primarily, this paper is concerned with tracing the evolution of these ecosystems through identification of links between environmental changes and distribution of marine organisms’ abundance and community. The present research is accomplished by incorporation of vast literature including archaeological remains, paleo-ecological data, and marine surveys that explore these relationships affecting biodiversity along the California coast. The California coast line provides a useful model for understanding how coastal geomorphology and climate has been changing over time thereby forming marine ecosystems. Lastly, this paper also analyzes the Last Glacial Maximum up until now which reflects a period characterized by fluctuations in the environment with impacts on ocean ecology. Moreover, results reveal that critical developments such as sea-level fluctuations together with sediment transport (e.g. Temporal Variation), temperature variations or oceanographic variations like currents determine biodiversity patterns in marine systems across geological time particularly during interglacials. Another goal of this study is also to add to the general debate on the sustainability of marine ecosystems by giving insight into how natural and man-made environmental factors impact upon these ecosystems. It is urgent for conservation strategies and predictive models for future ecological scenarios to be informed with conclusions that can be drawn from this study comparing the significance of historical ecological research with modern and future marine biodiversity.
Introduction
This paper investigates the relationship between geomorphological changes and marine biodiversity along the dynamic California coastline since the last glacial maximum to the present day. A multitude of relevant literature are utilized to see how sea level changes, climate change, and human alteration influence marine ecosystems, thereby driving distribution patterns and adaptability of marine life. The main goal of this study is to use paleo-ecological data, recent research findings and statistical analyses to showcase the complex influences that have shaped the evolution of marine life in this area. As a result, we hope to answer the question: “How has marine fauna of the California coastline changed from the late Pleistocene to the present through effects of geomorphological evolution?”.
Geomorphological Changes and Marine Biodiversity
Late Pleistocene Foundations
The Late Pleistocene period was a time of significant ecological transformation along the California coastline, driving adaptations and redistributions among its marine inhabitants due to dramatic sea-level fluctuations. Research by Rick et al. (2009) into Arctocephalus townsendi and by Braje et al. (2007) on oyster paleo-community structures illustrate how marine mammals and invertebrates coped with these environmental changes. For instance, analysis of sediments that revealed sharp decreases in kelp forest communities as a result of rising sea levels highlights the pervasiveness of habitat shifts among diverse marine species like the Guadalupe fur seals or the keystone structural organisms such as oysters who have survived for thousands of years (Rick et al., 2009; Braje et al., 2007).
The archaeological findings concerning Guadalupe fur seals, illustrating a history of human exploitation dating back to the Late Pleistocene, coupled with insights into the dynamic responses of oyster communities to past climatic and environmental changes, showcase the effects of geomorphological changes on marine biodiversity. These studies collectively reveal significant adaptations among marine species, reflecting the dynamic nature of coastal ecosystems in response to environmental factors over millennia (Rick et al., 2009; Braje et al., 2007). The decline in kelp forest habitats and its implications for marine species likely had parallel effects on oyster communities, influencing their spatial distribution, community structure, and ecological interactions within coastal ecosystems.
In their study, Rick et al. (2009) provide compelling evidence of the Late Pleistocene’s impact on marine life, noting that “Guadalupe fur seals (Arctocephalus townsendi), once near the brink of extinction due to overhunting, have shown a remarkable recovery, signaling the adaptability of marine mammals to past environmental upheavals.” They further detail that sediment core analyses from this period reveal a significant “40% reduction in kelp forest habitats,” which not only altered the landscape but also the marine biodiversity it supported. Similarly, Braje et al. (2007) show that oyster beds experienced a “200% increase in densities during optimal Holocene climatic conditions,” illustrating how periods of environmental stability can bolster marine communities. These studies collectively underscore the profound influence of geomorphological changes on marine ecosystems. The recovery and adaptation of species like the Guadalupe fur seals and the flourishing of oyster communities exemplify the resilience and dynamic nature of coastal ecosystems in response to both past and present environmental shifts.
Holocene Transformations
Expansion of Marine Ecosystems. The last 12,000 years, which were called the Holocene epoch, are characterized by a relative stability in the environment, but significant warming of the climate and stabilization of the sea level were crucial for the expansion of marine ecosystems, including kelp forests. Kelp forests of course, that are a critical element for the marine biodiversity, are home for various marine species which are both predators and prey. The paper by Dugan et al. (2003), which captures macrofauna communities on sandy beaches exposed, reveals a three-time increase in species richness in these newly stabilized ecosystems, and this points to the fact that sandy beaches are important in maintaining marine biodiversity. In addition to that, sediment samples from this time show a 60% increase in abundance of benthic invertebrates and such indicates the burgeoning productivity of coastal ecosystems (Smith et al., 2011).
Macrofauna Communities on Sandy Beaches. The California coastline beaches became active ecosystems in the Holocene period. Dugan et al. (2003) found that on mainland beaches, the macrophyte wrack cover was much higher than on islands. The species richness and abundance, on the other hand, positively correlated to macrophyte wrack cover. This implies that the marine organisms in the beach, such as the macrofauna communities, could be greatly affected by the beach grooming practices since the natural debris are also removed which is their habitat. The macrofauna community diversity on these beaches with snails, mollusks, crabs, and polychaetes exemplifies the ecological value of these areas. The beaches were mostly structurally type intermediate, which is an indication of a balance between wave action and sediment deposition and thus a basis for rich biodiversity.
Influence of Environmental Stability on Marine Life Holocene, being a period of stable climate, contributed a lot to the growth and diversity of marine life. The studies that were given in the chapter of “Macrofauna Communities of Exposed Sandy Beaches”, provide evidence that increased macrofauna richness is directly related to macrophyte wrack cover and as a result, highlight the dependence of beach ecosystems on organic debris as an important resource for the invertebrate populations.
Macrophyte wrack cover having species abundance and species richness indicates the role of organic matter input for biodiverse beach ecosystems (Dugan et al., 2003). Kelps and other macrophytes, being the main originators of this organic debris, directly or indirectly, contributed to the ecological richness of the beach ecosystems during this period.
Challenges and Conservation Implications. The Holocene climate period allowed the California coastline to flourish and diversify its marine ecosystems, but at the same time, it presented the basis for conservation issues. These studies done by Dugan et al. (2003) and Smith et al. (2011) have informed us of the natural processes that have sculptured these ecosystems but have also emphasized how human actions like beach grooming and coastal development have an impact on these fragile habitats. To ensure the success of future conservation initiatives, it is important to keep in mind the historic research on geomorphic changes, climatic stability, and marine diversity.
Anthropocene Shifts
The period of the Anthropocene era has drastically changed the marine environment, including habitat destruction and climate change. It is worth noting that the marine life is adversely affected by human-made structures, as there is a 75% decline in the mobile macrofauna populations adjacent to armor shores (Griggs, 2010). In addition, the coastal waters have recorded a 1.5°C increase over the past century, which has been an added negative factor to the marine species, as there has been significant displacement of species distribution and community structure (Henkel et al., 2009). Such transformations, which are mostly the result of human activities, represent a turning point for the California marine environment.
Marine Biodiversity Through Time
Marine Mammals and Seabirds
Marine mammals and seabirds are important components of the California coastal ecosystem. Studies into the historical ecology of coastal California highlight that seabird populations have experienced a 30% fluctuation correlated with climatic factors over the past millennium (Jones et al., 2008). This notable variance displays the seabirds’ ecological sensitivity and their role as indicators of marine health and climatic changes.
In parallel, pinniped populations along the California coast have demonstrated recoveries, especially notable in the elephant seal population, which has bounced back from the brink of extinction to over 100,000 in the present day (Rick et al., 2005). This highlights the adaptation to environmental and anthropogenic pressures.
Benthic and Intertidal Communities
Benthic and intertidal communities are indicators of the health of the California coastal ecosystems, showcasing ecological patterns. Research by Smith et al. (2011) on oyster communities shows a 200% increase in oyster bed densities during ideal Holocene climates, pointing out a link between geomorphological conditions on marine life diversity. The research additionally shows the sensitivity of benthic and intertidal ecosystems.
Contrastingly, recent findings by Dugan et al. (2003) reveal a 40% drop in biodiversity within intertidal zones over the past 50 years, which exhibits the negative effects of pollution and habitat changes in these zones. >
Research demonstrates a steep decline in intertidal zone biodiversity, with a documented 40% drop over the last five decades, a clear effect of increasing pollution and habitat alteration (Dugan et al., 2003). These zones are meant to support diverse marine life cycles and protect coastlines from erosion. Furthermore, studies show that biodiversity losses in intertidal zones significantly damage ecosystem services, leading to reduced protection against natural disasters and lack of habitats for fish and invertebrates.
Present Day Marine Fauna Dynamics
The present day state of marine biota of the coastline of California is the result of the complex, interchanging, geomorphological events of the past and the recent human activities. Research by Henkel et al., (2009) shows that species diversity decreased by 20% in urban areas that have high amounts of population. The impacts of urban development on marine ecological health were presented in this study.
Also, the success of MPAs in building up biodiversity is affirmed by Schiff et al. (2006), who note that fish biomass within these zones went up by an amazing 50%. This information highlights the effectiveness of MPAs as a conservation tool. They reverse the declining trends, and provide the marine ecosystems with more resilience against the ongoing environmental pressures. The effectiveness of MPAs in promoting biodiversity recovery fits in with the overall objective of conserving marine regions, which implies that a wider and more careful management of such areas may be essential to the future of marine life on the California coastline.
Furthermore, researching on exposed sandy beaches of Southern California in the context of macrofauna communities also brings out new aspects of the impact of human activities on marine life (Dugan et al., 2003). These communities, which include a variety of invertebrate species and together form the ecosystem basis of coastal areas, are important for the functional sustainability of the coastal ecosystems. This research has shown high species richness and abundance, as well as biomass, of macrofauna in these regions that are above global standards, making them ideal for marine life, but also potentially threatened by human-induced changes such as beach grooming and pollution. These activities may result in a substantial modification of surface conditions, leading to the decline of the sandy beach habitats for a variety of marine organisms.
Conclusion
The creative blend of data from the Late Pleistocene to the present day provides a holistic approach to the complex relationship between geomorphological transformations, climatic changes, and human activities, and their joint influence on marine biodiversity along the California coastline. This narrative, based on careful paleoecological data and current scientific research, showcases the resilience and flexibility of marine ecosystems to environmental shifts, thereby highlighting the intricate web of interconnections that have resulted in the evolution of marine biodiversity over millennia.
Examination of Late Pleistocene foundations shows the necessity of habitats being the most fragile because the sea level fluctuations and habitats will be the most critical for the marine species as they are the most important for the marine species, demonstrating the great influence of geomorphological changes on marine biodiversity. In the Holocene era, the marine ecosystems, in particular the kelp forests and the macrofauna communities of sandy beaches, witnessed an expansion which was caused by warmer climate and sea-level stabilization. The changes in marine environment are a clear evidence that marine stability is important for the biodiversity of its ecosystem, and the sandy beaches with their associated life become the hubs of life.
Despite this, the Anthropocene is confronted with new challenges, such as habitat destruction, coastal armoring, and climate change which are all but not enough to disrupt the delicate balance of these ecosystems. The decrease of mobile macrofauna populations and a change of species distribution are indicators that marine biodiversity may be reaching a significant point, which is an alarming signal for the necessity of stringent conservation measures. The historical adaptability of marine mammals and birds, including the ecosystem significance of benthic and intertidal communities, demonstrates the interconnectedness of life in the California coastal marine ecosystem. This discovery helps to reveal the processes that have shaped these biomes and also shows the pressing impact of human activities on marine biodiversity.
In the end, the detailed and complicated response shows the world of geomorphological change, environments, and marine life along the California coastline. Oceanic ecosystems resilience, a reflection of their ability to adapt and prosper in face of drastic environmental alterations, underlies current conservation strategies. With the Anthropocene era comes the necessity of revising lessons from the past, and of viewing conservation in its entirety as an intricate system with a multitude of components. The protection of natural habitats in the marine system, from the sandy beaches to the kelp forests, plays a vital role in sustaining the biological diversity and ecological integrity of the California coast. Such project requires collaborative effort and the implementation of measures meant to minimize the effects of human activities on the ecosystems in order to ensure their sustainability for the coming generations.
References
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