4 research outputs found
Intra‐Annual Variability in Responses of a Canopy Forming Kelp to Cumulative Low Tide Heat Stress: Implications for Populations at the Trailing Range Edge
Anthropogenic climate change is driving the
redistribution of species at a global scale. For marine
species, populations at trailing edges often live very
close to their upper thermal limits and, as such,
poleward range contractions are one of the most
pervasive effects of ongoing and predicted warming.
However, the mechanics of processes driving such
contractions are poorly understood. Here, we
examined the response of the habitat forming kelp,
Laminaria digitata, to realistic terrestrial heatwave
simulations akin to those experienced by intertidal
populations persisting at the trailing range edge in the
northeast Atlantic (SW England). We conducted
experiments in both spring and autumn to determine
temporal variability in the effects of heatwaves. In
spring, heatwave scenarios caused minimal stress to
L. digitata but in autumn all scenarios tested resulted
in tissue being nonviable by the end of each assay. The
effects of heatwave scenarios were only apparent
after consecutive exposures, indicating erosion
of resilience over time. Monthly field surveys
corroborated experimental evidence as the
prevalence of bleaching (an indication of physio
logical stress and tissue damage) in natural
populations was greatest in autumn and early winter.
Overall, our data showed that L. digitata populations
in SW England persist close to their upper
physiological limits for emersion stress in autumn. As
the intensity of extreme warming events is likely to
increase with anthropogenic climate change, thermal
conditions experienced during periods of emersion
will soon exceed physiological thresholds and will
likely induce widespread mortality and consequent
changes at the population level
Ghost crab burrow density at Watamu Marine National Park: an indicator of the impact of urbanisation and associated disturbance?
Ghost crab (Ocypode species) burrow densities have previously been used as an indicator of anthropogenic impact. This study aimed to assess the burrow density of Ocypode species (O. ryderi and O. cordimanus) at four sites across Watamu Marine National Park, Kenya. Two sites were in front of hotel complexes (denoting a high degree of urbanisation), and two were in front of residential housing among coastal scrub (denoting a low degree of urbanisation). The findings reveal significantly higher burrow densities at sites in front of residential housing, which was the less developed area. This provides further evidence that Ocypode burrow densities can be used, where other methods would be impractical, to estimate the impact of some human activities along beach fronts, such as at Watamu Marine National Park
The Habitats and Biodiversity of Watamu Marine National Park: Evaluating Our Knowledge of One of East Africa's Oldest Marine Protected Areas
Watamu Marine National Park (WMNP) is one of the oldest no-take Marine Protected Areas (MPAs) in the world. Since its establishment in 1968, it has been the subject of a number of scientific studies as well as suffering from a range of modern threats to coastal marine habitats. The current state and conservation value of WMNP is documented in terms of habitat, biodiversity, and available scientific literature. There were 101 published references relating to WMNP found, which mostly focus on coral reef ecology, with less attention to other topics, such as biodiversity, socio-economics, or the ecology of non-coral reef habitats. The habitat map produced of WMNP is the first to show this level of detail and the only habitat map of a Kenyan MPA. Nine habitat categories were mapped; revealing that the most dominant habitat type is seagrass and the least is coral reef. Species lists were collected for fish, echinoderms, molluscs, crustaceans, corals, and seagrass, and species abundances were used to estimate total species richness, species diversity and sampling completeness. There were 18 species across all groups that fall into a category of conservation concern (other than Least Concern or Not Evaluated) on the IUCN Red List and 8 species found which are currently undescribed. The findings of this paper emphasise the importance of non-coral habitats in the WMNP, such as seagrass beds, and the need for more research into the ecology and conservation importance of these habitats. The information provided in this paper provides a comprehensive overview to any scientist or conservationist wanting to carry out further work in WMNP