title: Context-specific bioturbation mediates changes to ecosystem functioning

authors: Needham, Hazel Rosemary

subjects: benthic–pelagic coupling

abstract: Species are often grouped according to their biological or functional traits to better understand their contribution to ecosystem functioning. However, it is becoming clear that a single species can perform different roles in different habitats. Austrohelice crassa, a burrow-building mud crab shifts its primary bioturbational role to that of a vertical mixer in non-cohesive sediments as frequent burrow collapse greatly enhances sediment reworking. We conducted in situ crab density manipulations in two sediment environments (a non-cohesive sand and a cohesive muddy-sand) to examine if the contextspecific functional roles were linked to changes in solute fluxes across the sediment–water interface. Across both habitats, we show that A. crassa regulated nutrient cycling, creating strong density driven effects on solute exchanges. Increasing crab density increased sediment O₂ demand and the flux of NH₄⁺ from the sediment, indicating much of the response was physiologically driven. Clear interactions between A. crassa and microphytobenthos were also detected in both habitats. Despite lowering microphyte standing stock through deposit feeding, A. crassa increased benthic primary production per unit of chlorophyll a. Our experiment also revealed important context-specific differences, most notably for NH₄⁺ fluxes, which were higher where burrows and their associated microbial communities were most stable (muddy-sand). This study highlights the need to integrate interactions between organism behavior and habitat type into functional group studies to broaden conceptual frameworks and avoid oversimplification of highly complex organism–sediment interactions.

text: Context-specific bioturbation mediates changes to ecosystem functioning Species are often grouped according to their biological or functional traits to better understand their contribution to ecosystem functioning. However, it is becoming clear that a single species can perform different roles in different habitats. Austrohelice crassa, a burrow-building mud crab shifts its primary bioturbational role to that of a vertical mixer in non-cohesive sediments as frequent burrow collapse greatly enhances sediment reworking. We conducted in situ crab density manipulations in two sediment environments (a non-cohesive sand and a cohesive muddy-sand) to examine if the contextspecific functional roles were linked to changes in solute fluxes across the sediment–water interface. Across both habitats, we show that A. crassa regulated nutrient cycling, creating strong density driven effects on solute exchanges. Increasing crab density increased sediment O₂ demand and the flux of NH₄⁺ from the sediment, indicating much of the response was physiologically driven. Clear interactions between A. crassa and microphytobenthos were also detected in both habitats. Despite lowering microphyte standing stock through deposit feeding, A. crassa increased benthic primary production per unit of chlorophyll a. Our experiment also revealed important context-specific differences, most notably for NH₄⁺ fluxes, which were higher where burrows and their associated microbial communities were most stable (muddy-sand). This study highlights the need to integrate interactions between organism behavior and habitat type into functional group studies to broaden conceptual frameworks and avoid oversimplification of highly complex organism–sediment interactions.

year: 2011

title: Interpretation of pre-AD 472 Roman soils from physicochemical and mineralogical properties of buried tephric paleosols at Somma Vesuviana ruin, southwest Italy

authors: Inoue, Yudzuru

subjects: Mt. Vesuvius

abstract: This study aimed to interpret soil fertility around Somma Vesuviana in ancient Rome from investigation of buried paleosols developed beneath thick pumice deposits of the AD 472 Pollena eruption of Mt. Vesuvius. Two buried pedons derived mainly from phonolitic tephra deposits of the AD 79 Pompeii eruption, and ancient construction waste, were excavated and sampled at the Somma Vesuviana villa ruins on the northern flanks of Mt. Vesuvius, Italy. For comparison, a buried paleosol on equivalent Pompeii tephra deposits in a nearby forest, and a modern soil on AD 1631 tephra deposits (compositionally similar to Pompeii eruptives) in an adjacent orchard, were similarly analyzed for physical, chemical, and mineralogical properties, including phosphorus fractions and primary mineral compositions. The two buried pedons in the ruin had abundant available P and K and contained moderate amounts of exchangeable cations. Leucite was the dominant primary mineral and, with alkali feldspars, is probably the major source of K in the buried horizons. A high content of “authigenic P (Ca-bound P)” characterized all the pedons. We concluded that the buried Somma Vesuviana paleosols had a relatively high ability to supply nutrients and that they were fertile prior to the AD 472 eruption, although manuring to increase nitrogen was probably needed to maintain high productivity. Their physical properties such as water retention were probably enhanced by small but significant amounts of short-range order clays.

text: Interpretation of pre-AD 472 Roman soils from physicochemical and mineralogical properties of buried tephric paleosols at Somma Vesuviana ruin, southwest Italy This study aimed to interpret soil fertility around Somma Vesuviana in ancient Rome from investigation of buried paleosols developed beneath thick pumice deposits of the AD 472 Pollena eruption of Mt. Vesuvius. Two buried pedons derived mainly from phonolitic tephra deposits of the AD 79 Pompeii eruption, and ancient construction waste, were excavated and sampled at the Somma Vesuviana villa ruins on the northern flanks of Mt. Vesuvius, Italy. For comparison, a buried paleosol on equivalent Pompeii tephra deposits in a nearby forest, and a modern soil on AD 1631 tephra deposits (compositionally similar to Pompeii eruptives) in an adjacent orchard, were similarly analyzed for physical, chemical, and mineralogical properties, including phosphorus fractions and primary mineral compositions. The two buried pedons in the ruin had abundant available P and K and contained moderate amounts of exchangeable cations. Leucite was the dominant primary mineral and, with alkali feldspars, is probably the major source of K in the buried horizons. A high content of “authigenic P (Ca-bound P)” characterized all the pedons. We concluded that the buried Somma Vesuviana paleosols had a relatively high ability to supply nutrients and that they were fertile prior to the AD 472 eruption, although manuring to increase nitrogen was probably needed to maintain high productivity. Their physical properties such as water retention were probably enhanced by small but significant amounts of short-range order clays.

year: 2009

title: Mapping Māori knowledge from the past to inform marine management futures

authors: Paul-Burke, Kura

subjects: mātauranga Māori

abstract: This article provides an overview of research which used mātauranga moana (Māori marine knowledge systems) to inform and assist Western science field research methods and surveys. Place-based Māori marine knowledge identified the traditional distribution range and sizing of taonga (culturally important) species in traditional coastal areas which had been fished and managed by consecutive generations of Māori; kina, Evechinus chloroticus, sea urchin; koura, Jasus edwardsii, red rock lobster; kūtai, Perna canaliculus, green lipped mussel; and pāua, Haliotis iris, abalone. This knowledge was then mapped and used as the baseline for sub-tidal marine science field research surveys. Findings from the transdisciplinary marine research was used to develop management actions to assist Māori and Government entities for improving, enhancing and safeguarding marine taonga species into the future. This article critically discusses and demonstrates the relevance and complementarity of mātauranga Māori and Western science, and the importance of kaupapa Māori strategies for empowering Māori collaboration and voices in marine research co-development, implementation and communication.

text: Mapping Māori knowledge from the past to inform marine management futures This article provides an overview of research which used mātauranga moana (Māori marine knowledge systems) to inform and assist Western science field research methods and surveys. Place-based Māori marine knowledge identified the traditional distribution range and sizing of taonga (culturally important) species in traditional coastal areas which had been fished and managed by consecutive generations of Māori; kina, Evechinus chloroticus, sea urchin; koura, Jasus edwardsii, red rock lobster; kūtai, Perna canaliculus, green lipped mussel; and pāua, Haliotis iris, abalone. This knowledge was then mapped and used as the baseline for sub-tidal marine science field research surveys. Findings from the transdisciplinary marine research was used to develop management actions to assist Māori and Government entities for improving, enhancing and safeguarding marine taonga species into the future. This article critically discusses and demonstrates the relevance and complementarity of mātauranga Māori and Western science, and the importance of kaupapa Māori strategies for empowering Māori collaboration and voices in marine research co-development, implementation and communication.

year: 2020